Mustang II Construction Manual.

 

CENTER SECTION_ 3

FLAP____ 8

FORWARD FUSELAGE________ 11

FUEL TANK________ 15

MUSTANG FUEL SYSTEM 16

FUSELAGE TAIL CONE________ 17

HORIZONTAL STABILIZER________ 21

VERTICAL FIN_____ 24

CONTROL SURFACE CONSTRUCTION___ 25

ELEVATOR CONSTRUCTION___ 25

RUDDER CONSTRUCTION___ 26

CANOPY INSTALLATION_____ 27

CANOPY FRAME CONSTRUCTION___ 28

FITTING THE PLEXIGLASS CANOPY________ 28

COWLING ATTACHMENT______ 32

WING___ 34

WING JIG 34

WING CONSTRUCTION___ 35

AILERON CONSTRUCTION___ 39

TOOL REQUIREMENT FOR ALUMINUM AIRPLANE CONSTRUCTION___ 41

APPENDIX CONSTRUCTION NOTES__ 42

NOTE #1:  FORMING RIBS AND BULKHEADS -______ 42

NOTE #2:  WING FITTING ATTACHMENT PROCEDURE_______ 44

TOOLS AND MATERIALS NEEDED_______ 44

PROCEDURES___ 44

POSITIONING THE FORWARD FITTINGS_______ 45

DRILLING_______ 45

POSITIONING THE AFT FITTING 45

BOLT INSTALLATION__ 46

FINAL ASSEMBLY (lower Fitting)_ 46

INSTALLING UPPER SET OF FITTINGS_______ 46

ESTABLISHING DIHEDRAL_______ 46

ALTERNATE WING FITTING METHOD_______ 47

REAMING FOR WING ATTACH BOLTS_ 47

EXPLANATION__ 48

NOTE #3:  POSITIONING OF SKINS -_ 48

NOTE #4:  RIVETS - 48

NOTE #5:  FORMING THE LEADING EDGE AND TAIL SECTION SKINS__ 49

NOTE #6:  ATTACHING THE FIBERGLASS TIPS -_ 49

NOTE #6-1: MAIN SPAR -_______ 49

NOTE #7:  DIMPLING PROCEDURE -_____ 49

NOTE #8:  INSURING TIGHTLY FITTED EDGES - 50

NOTE #9:  LAYING OUT THE METAL BLANKS - 50

NOTE #10:  CONTROL SURFACE CONSTRUCTION -__ 50

NOTE #11:  MISCELLANEOUS CONSTRUCTION INFORMATION____ 50

REFERENCE MATERIALS________ 51

SOURCES OF MATERIAL________ 52

FLIGHT TESTING THE MUSTANG 53

 


CENTER SECTION

 

 

1.           Assemble Center Section Main Spar components as shown in drawings 220.002, .006, and .007.  See Folding Wing Section for additional notes if including this option.

 

2.           Determine the AFT face of each Spar Cap Extrusion.  Cut the extrusion that will become the top of the spar to 89".  Note that this will match the length of the Spar Webb.

 

3.        To maintain airfoil continuity it may be necessary to reduce the angle of the forward leg of the bottom Spar Car Extrusion. Note:  This change is on the section of the leg forward of raised portion of the extrusion.  See dwg 220.002 for details.  This can be done easily by using a hand held belt sander.  This requires removing .012" of material along the edge of the Cap, tapered to zero, to the raised portion of the extrusion.  (Note:  Many builders elect not to perform this operation.  Trial fit your ribs to the spar to see if it is necessary.)

 

4.        Main Spar Holding Fixture - A fixture for positioning and holding the spar components should be constructed at this time. It consists of a straight wood board 1" x 6" x 88" long, with three 1"x 6"x 8" pieces nailed on, one in the center and one at each end.  The 88" length allows for use of the Extrusion Positioning Template at each end.  This fixture is illustrated in Photo #71.

 

5.        The Extrusion Positioning Template is detailed in Photo #70.

 

6.        Clamp one Extrusion in place on the Holding Fixture.  Note: The Spar Cap Extrusions are positioned in this fixture with the AFT surface upward.  Fabricate three spacers of .125" aluminum 1/2" wide x 2.359" long.  Using wood screws, attach spacers to the blocks on the ends of the fixture, near the ends and in contact with the Extrusion.

 

7.        Clamp the other Extrusion in position against the two spacers.  The spacers will position the ends of this Extrusion to obtain the correct Spar dimension.  Insert and attach the third spacer in the center of the Extrusions to obtain the correct dimension.  Note:  A slight bow in the Extrusions may be noticed preventing contact with the center spacer.  In this case the Extrusions can be drawn together by the use of a large "C" clamp. Protect the Spar Caps from nicks by using aluminum scrap under the clamp.  Sight down the Spar to insure that it remains straight and true.  Correct any error NOW.

 

8.        To facilitate checking measurements and to insure accuracy an Extrusion Positioning Template is constructed per the dimensions in Photo #70.

 

9.        Lay out all rivet hole positions on the Spar Webb P/N 220.303 EXCEPT those at the Rib Attach Angles locations, Wing Attachment Spacers P/N 220.310 locations, and at the Landing Gear Doubler P/N 220.311 locations.  Be certain to maintain the proper rivet to edge distance on both the Spar Webb and Extrusions. (5/16" is optimum, 1/4" is minimum)

 

10.      Drill eight of the rivet hole positions laid out on the Webb above using a #40 size drill bit.  The holes should be spaced over the full length of the Webb, four holes spaced evenly along the top and four along the bottom of the Webb.  Position the Webb on the Extrusions and transfer the location of the eight holes to the Extrusions.  Remove the Webb and check that hold locations are the correct edge distance on the Extrusions.  Drill the eight locations on the Extrusions using a #40 drill bit.  NOTE:  Refer to the Construction Notes for the proper technique for drilling thick aluminum.  NOTE:  The Spars supplied in Mustang Aircraft kits incorporate the above operations.

 

11.      Make any adjustments to the rivet locations on the Webb before proceeding.  Drill all of the remaining rivet hole locations in the Webb at this time.  Cut holes in Sta.  24.5 right and left for the Landing Gear.

 

12.           Position the Webb on the Extrusions and clamp in place at the eight locations using Cleco fasteners.  Using a #40 size bit drill all of the rivet holes in the Extrusions using the Webb as a template.  Use a sufficient number of Cleco's as drilling proceeds to securely hold the pieces together.  NOTE:  When drilling the holes in the Webb and Extrusions do not drill any holes in the area of Sta. 44.0 as these will be drilled when fitting the Wing Attachment Butt Angles and Spacers.  If AN-3 bolts will be used for attaching the Butt Angles these rivet locations will not be used.

 

13.           Fabricate Rib Attachment Angles P/N 220.309 for the aft side of the spar, including rivet holes.  Position the Angles on the Extrusion - Webb assembly and drill the rivet holes in the Extrusions.  Fit the Landing Gear Doubler steel pieces P/N 220.311 to the Spar in a similar manner.  Fit the Wing Attachment Spacers P/N 220.310 for the aft side a this time.  NOTE:  The edge of the Spacers that fits against the corner of the Extrusion must be radius to match the Extrusion.

 

14.  With Cleco's and clamps securely holding the pieces together the assembly can be removed from the fixture and turned over, forward face up.  If the 1" x 6" wood blocks interfere with the Cleco's or Rib Angles it may be necessary to substitute some other blocking material.  Be certain that the assembly is resting firmly and has not been twisted in any way.

 

15.           Position and clamp in place the forward Rib Attachment Angles.  To facilitate drilling these angles the Spar assembly is turned to permit drilling the rivet holes from the aft side.  To insure that you will be drilling into the center of the angle draw a centerline on the flat side of the angle.  However, this line is only a guide do not move the angle from position just to line up the line with the rivet hole.  Drill bits the size of a #40 can wander while cutting through thick material thus the holes don't pass straight through and would not meet the line on the angle.

 

16.      Make certain the Rib Angles, Webb, and Spar Caps are tightly clamped together to prevent the build up of drilling chips between the pieces.

 

17.      Redrill all size #40 holes with a #30 drill bit. Disassemble components and label each part to insure that it will be reassembled in the same location.  Clean off chips and deburr all holes.

 

18.  The inside surface of the Spar Caps at the location of the Wing Attachment Fittings bust be ground away enough to provide clearance for the Wing Fittings.  The forward side flange is ground more than the aft side due to the angle of the Extrusion. The ground surface need not extend to the leg of the Extrusion as there is a spacer between the Fitting and the leg.  It is important that the curve of the leg to the flange be smooth and even.  AVOID any sharp corners.  This task can be done using medium grit paper on a disk or belt sander, or by hand using a "rat tail" file as it is only necessary to remove enough for clearance of the Fittings.  See dwg. 220.007 for details.

 

19.      It will be easier to determine the amount of material to remove if it is done at the time of attaching the Wing Fittings. In this case the Spacers P/N 220.310 should not be riveted in place until this operation is completed.

 

20.      Now is the time to chemically treat all Spar components to prevent corrosion.  It is especially important to treat and prime all steel components that come in contact with aluminum parts otherwise a galvanic action begins between the dissimilar metals. This will lead to very rapid corrosion and failure of the parts. Aluminum Pre-Wash and Conversion coating chemicals are available from auto paint stores and aircraft supply houses.  This treatment is recommended in coastal areas where there is salt in the atmosphere.

 

21.           Reassemble the Spar components using Cleco fasteners. Verify the alignment of all parts.  Support the assembly on blocking or other means to give access for riveting.  Be certain that there is no twist or bow in the assembly.

 

22.  Rivet the components together.  Because of the weight of the assembly riveting may be difficult.  A size 4x rivet gun is desirable although a 3x gun may suffice or, a mechanical rivet squeezer or, the hand riveting method described in the Construction Notes may be used.

 

23.  Install the Wing Attachment Fittings per the detailed description in the Appendix.  The builder may elect to complete the construction of the Center Section (less Leading Edge Skins) prior to fabricating the outer Wing Main Spars.  In this instance the Wing Attachment Fittings can be positioned using the Wing Fitting Location Templated sepicted in the Appendix.  NOTE:  The Spar Positioning and Wing Fitting Location Templates are supplied in Mustang Aircraft Kits.

 

24.  Fit and attach the Spar Butt End Spacers and Angles.

 

25.      The Landing Gear Mounting Brackets for the Main and Rear Spars should be completed before locating the Mounting Doublers or drilling the necessary holes in the Spars.  The 1/8" 4130 steel is difficult to cut and bend accurately, so to avoid misalignment use the finished pieces to locate the holes.  NOTE: To cut 4130 steel it is necessary to use a very slow cutting saw, either saber or band saw.  On band saws a speed of about 150 feet per minute blade travel is required.

 

26.  Prime ALL steel parts with zinc-chromate primer.  There must not be any bare steel to aluminum contact.

 

27.  Fit the Rear Spar Webb and Rear Spar Reinforcement together. See the Folding Wing Section for the additional instructions if you are including this option.

 

28.      The location of the Rear Spar Rib Angles must match those on the Main Spar.  Do not attach the Flap Reinforcement at this time.

 

29.           Fabricate the Sta. 99.35 Bulkheads and fit them to the Rear Spar.  Drill the rivet holes in the Bulkheads and Spar, but, do not fasten at this time.  Temporarily attach short pieces of 3/4x3/4 angle in place of the Bulkheads as they are needed to support the Ribs during the initial assembly of the Center Section.

 

30.  Deburr all holes on the Rear Spar and chemically treat the parts.

 

31.           Perform all riveting operations to assemble the Main and Rear Spars, except the Landing Gear fittings and Sta. 99.35 Bulkheads, at this time.

 

32.      The two Rear Spar Landing Gear Brackets can be attached at this time.  Apply several coats of zinc chromate primer on mating surfaces, preferable attaching bracket while the primer is still wet.

 

33.           Construct the Center Section Ribs, Bulkheads, and Control Supports per drawings 220.001, .004, and .005.  Center Section Ribs can be formed using Sta.  47.25 forming blocks, if they are reduced in size to compensate for the thicker material of the Center Section Ribs.

 

34.      Note that the Center Section Ribs at Sta. 20.0, right and left, differ from the other ribs.  The top flange of these two ribs is constructed by the attachment of an extruded 3/4x/3/4x.062 aluminum angle, instead of being formed in the regular manner.

 

35.           Position and drill all rivet holes for attachment of the Control Stick Bearings (P/N 220.331) to the Supports (P/N 220.330 & .330-1), but, do NOT rivet at this time.  The Stick Bearings are attached at the time of installing the Control Stick Assembly.  The Stick Assembly should be completed before the Center Section Skins are riveted in place, otherwise riveting of the Stick Bearings will be very difficult.

 

36.           Position Center Section Main and Rear Spars in the Construction Jig in the same manner as described for the Wing Jig.  Take care in aligning the Jig as it determines the squareness of the finished section.  See Jig section of this manual for construction of the Wing Jig.

 

37.      Attach all Center Section Ribs, Bulkheads, Seat and Wing Walk Stiffeners.  Wing Walk Doubler material (P/N 220.337) may be attached to the Stiffeners at this time, using (4) flush type rivets on each.  The surface of the Wing Walk Doublers is flush with the Rib flanges and is completely secured when attaching the Top Skins.

 

38.      For Center Section Skin installation see drawings 220.002, .004, and .008.  Cut skins per drawing 220.008.  Cut 220.341 and .341-1 OVERSIZE and tim to fit upon installation.

 

39.           Position Center Section Bottom Main Skin (P/N 220.343) and drill all rivet holes.  Attachment rivets are 1/8" dia.  and require a #30 size drill.  It is desirable to initially drill through the Main Spar Cap Extrusion with a #40 drill, then ream with a #30 drill.  This will eliminate the possibility of oversize holes in the thick material.

 

40.      The Center Section Bottom and Top Skins must butt against the raised portion of the Main Spar Cap Extrusion.

 

41.      The bottom Skin (P/N 220.343) is attached to all structure, EXCEPT the Main Spar, by means of AN 426 AD4-4 flush rivets with the skin and structure dimpled.  Use AN 470 AD4 universal head rivets to attach skin to the Main Spar.  Construction will be simplified if the Bottom Skin is not riveted in place until after the Top Skin is installed.  NOTE:  See all of the following instruction steps BEFORE riveting any of the Skins in place.  A number of components are riveted together in one operation.

 

42.      Fit the Center Section Top Skin (P/N 220.342) in a manner similar to the Bottom skin.  Attachment is by AN 426 AD4 rivets. The Main Spar Cap is prepared by countersinking per the detail on drawing 220.008.  DO NOT drill rivet holes in Sta. 20.00 Ribs 220.323 and 220.323-1 at this time.  See step 47.  Cut opening in the skin for installation of fuselage Sta.  99.35 bulkheads. Attach Skin to the Rear Spar with a few flush rivets between Sta. 20.0, left and right, as the Baggage Compartment Floor will complete the installation.

 

43.      Fit the Center Section Leading Edge Skins (P/N 220.341 and 220.341-1) after forming the front radius.  NOTE:  The forward edge of the installed Skin is at Fuselage Sta.  56.625.  Leave these skins long at the inboard end for trimming to fit the curve of the Fuselage Side Skins.

 

44.      All rivet holes can be drilled at this time, but, the fuselage construction will be easier if the Leading Edge Skins are not riveted in place until the Forward Fuselage Side Skins are fitted.  Skins are attached to the Ribs and Main Spar Extrusion using AN 426 AD4 flush rivets.  The Leading Edge Skins must have access openings to the Landing Gear Brackets.  Make this provision NOW.

 

45.           Position the Flap Piano Hinge, and Hinge Reinforcement, on the trailing edge of the Center Section Bottom Main Skin, with the centerline of the Hinge at Fuselage Sta. 101.725.  The Flap Piano Hinge is a 6 foot length of aluminum piano hinge (1-1/4" open width)  centered on the skin trailing edge.  To maintain a smooth bottom skin, a shim of scrap aluminum strip should be added at each end of the Hinge, between the skin and the Hinge Reinforcement.

 

46.      With all skins in place, use the Airfoil Profile boards to properly locate the Bottom Main Skin trailing edge.  The position of the skin trailing edge will determine the location of the Flap Hinge Reinforcement on the Rear Spar so that its rivet holes can be drilled.  Usa AN 470 AD4 rivets to attach the Reinforcement to the Rear Spar however, a bling type rivet (cherrymax) may be used if desired.  Use AN 426 AD4 flush rivets to attach the Flap Hinge and Reinforcement to the skin.  See Flap instructions for additional information.

 

47.      The Fuselage is attached to the Center Section by means of a Fuselage Attachment Stringer on Ribs 220.323 and 220.323-1 (wing Sta.  20.0).  The Stringer is an apple extrusion 3/4x3/4x.062 6061-T6 aluminum, extending from Fuselage Sta. 47.75 to Sta. 114.75 (67" long).j  See step 42 above.  See drawing 220.01 section A-A for detail.  These extrusions bend inward (top view) from the Sta. 20.0 Rib to begin the forward and aft taper of the Fuselage.  They bend inward 3 degrees at Fuselage Sta.  73.75 and 9 degrees at Sta.  99.35 (20" radius).  These Fuselage Attachment Angles should be fitted and attached when riveting the Center Section Top Skin.  Use rivets AN 470 AD4 on a 5/8" spacing.

 

48.           Remove the scrap angles and rivet in place Fuselage Sta. 99.35 Bulkhead members.  The Safety Belt Attachment Angles should be positioned and attached to the Rear Spar at the time of fitting the Top Skin and Sta. 99.35 bulkhead members.  See drawing 240.013 for details.  NOTE:  The Belt Attachment Angle (P/N 220.417) is aligned with the Top Skin.  Also note that a bushing (.187 ID x .250 long) is employed so that the Belt Attachment Bracket is free to swivel when the bolt is tightened. Rivet Sta. 20.0 Ribs to the Sta. 99.35 Bulkheads.

 

49.      The Center Section Top Skin may now be riveted in place.  As considerably more riveting is involved in attaching the Top Skin, it is recommended that it be done first.  Seat Attachment components P/N 240.410 or, what is required for your particular arrangement should be installed at this time.

 

50.      Rivet the Flap Hinge Reinforcement to the Rear Spar before riveting the Center Section Bottom Skin.  Alternatively, the Flap Hinge Reinforcement may be attached using Cherry "pop" rivets. NOTE:  To maintain a smooth transition from the Center Section to the Outer Wing panels, it is important that the Leading Edge of both the Center and Outer panels match.  Therefore, the station location of the Leading Edge is important.  This distance can be measured from the forward face of the Main Spar.

 

51.  Position the two Control System Tunnel Angles (P/N 240.408 and 240.408-1) per drawing 240.014.  NOTE:  Their position is Not symmetrical to the aircraft centerline.  These angles are formed from .025 aluminum and shaped to match the contour of the wing. The angles extend to the rear of the Baggage Compartment and the area where these angles pass over the Rear Spar is NOT riveted in place until the Baggage Floor is installed.

 

52.      The Center Section Bottom Skin may now be riveted in place. NOTE:  If you have plans to install additional fuel tank (s) in the Center Section do not rivet the Bottom Skin until you have completed the fuel tank (s).

 

53.      This completes the assembly of the Center Section except for the installation of the Aileron Control linkages.

 

This completes the Center Section

 

FLAP

 

1.        The Center Section construction should be completed to the stage of having the Bottom Wing Skin fitted and drilled before beginning the assembly of the Flap.

 

2.        trim the trailing edge of the Center Section Bottom Wing Skin to 2-3/8" aft of Sta. 99.35.

 

3.           Fabricate the Flap Ribs, Skins, Spar, Spar Doubler, Hinge Reinforcement, and Flap Control Arm assemblies per the drawings. If you are using the Folding Wing Option see additional instructions regarding the length of the Flap.

 

4.        Locate and mark the center of the Flap Bottom Skin, the Flap Hinge, and the Flap Spar.  NOTE:  The Flap Doubler and Control Arm Assemblies are offset to the right of center approx. 1-1/2".

 

5.           Position the Flap Hinge and Flap Spar on the Flap Bottom Skin, per the drawings, with their centers aligned.  Adjust the Hinge so that the centerline of the Hinge Pin is 1/16" forward of the edge of the Flap Bottom Skin.  Clamp this assembly together. NOTE:  The Hinge does not extend the ends of the Flap Spar.

 

6.  Drill the rivet holes through the Flap Spar, Hinge and Flap Bottom Skin at this time.  Fit 2 Filler pieces (.063 al.) at the Hinge ends to fill the space between the Spar and Skin.  Provide some means to retain, and to remove, the Hinge Pin for servicing the Flap in the future.

 

7.  Position the Flap Spar Doubler and Control Arm Assemblies on the Spar right of center per the drawings.  Clamp in place and drill rivet holes per drawings.  This location should align with the Flap Handle mechanism installed in the Center Section.  NOTE: The upper surface of the Control Arm Ribs should provide a smooth transition for the Top Skin to bend over the top of the Flap Spar.

 

8.        Fit the Flap Spar, Hinge, and Skin assembly to the trailing edge of the Center Section Bottom Skin by aligning the centerline marks.

 

9.        The Hinge should align so that there is a .125 gap alone the hinge line between the Flap Skin and Center Section Skin.  Clamp in place.  Work the hinge by moving the Flap assembly to insure that there is no binding.  Binding would be caused by a curve in fitting the Hinge.  The hinge line must be straight.

 

10.      Be sure to position the Hinge under the Hinge Reinforcement 220.312.  Drill a few of the hinge line rivet holes to secure the Flap Reinforcement in proper alignment to the Center Section Bottom Skin and the Rear Spar.  Note:  If the Folding Wing Option is used the Hinge Reinforcement must be shortened to clear the pivot fittings.

 

11.      Drill the remaining rivet holes through the Flap Spar, Hinge, Filler pieces, and Hinge Reinforcement at this time.

 

12.           Remove this assembly from the Center Section with the Hinge attached to the Flap.

 

13.      The next step is to fit the Flap Trailing Edge Extrusion to the Flap Bottom Skin.

 

14.      Place the Flap Spar, Hinge and Bottom Skin assembly on a FLAT surface and lay the Extrusion along the trailing edge of the Flap Bottom Skin.

 

15.      Fit the 3 Flap Ribs in place between the Spar and Extrusion. Adjust the fit of the Ribs both in length and in height at the Extrusion end at this time.  Set the Extrusion aside.

 

16.      Locate and drill the Rib attachment holes in the Flap Spar. NOTE:  Be sure that the Bottom Skin remains tight to the Spar and that the Skin stays FLAT.  Cleco the Ribs in place.

 

17.      Locate and drill the rivet holes to attach the Ribs to the Bottom Skin.  Again, be sure that the Skin remains flat and true. Cleco the Ribs to the Bottom Skin.

 

18.           Position the T.E. Extrusion along the edge of the Bottom Skin insuring that the skin is tight to the raised portion of the Extrusion.

 

19.      Lay the Flap Top Skin on top of this assembly so that it also fits tightly to Extrusion.  Locate and cut out an opening in the Top Skin for the Control Arms.

 

20.      Secure the Skins to the Extrusion with a tape such as masking or Duct tape.  After taping check that the Extrusion lays FLAT.

 

21.      Locate and drill the rivet holes to attach the Top Skin to the Flap Spar, the Spar Doubler and the 3 Flap Ribs.  Cleco the Top Skin in place.

 

22.      Even though the previous steps where designed to insure that the Extrusion is held true by the tape --- Don't count on it! Re-check the straightness of the Trailing Edge before proceeding. NOTE:  If it is difficult to keep the edge straight clamp a suitable length of stiff aluminum angle to the bottom of the T.E.

 

23.      Layout the location of all of the rivet holes in the T.E. The holes will pass through the Top Skins, the Extrusion and the Bottom skin all at once.  Place a length of wood under the T.E. to protect your work surface.  Drill the holes by starting with one hole in the center and the second and third holes out 6" to 9" from the center.  Place Cleco's in the holes as they are drilled.  Check that the T.E. remains straight.  Alternate from side to side of center and until all of the rivet holes are drilled.

 

24.           Disassemble and deburr the Flap components.

 

25.      Re-assemble the components but, without the Top Skin in place.

 

26.      Locate and fit the Flap Skin Stiffening Angles along the Bottom Skin.  Be sure that the Angles will NOT contact the Top Skin when it is in place.  Drill the rivet holes per the drawings.

 

27.  Lay the Top Skin in place and note the location of the Bottom Skin Angles.  The Top Skin Stiffening Angles face the opposite way from the Bottom Skin Angles and they must not interfere with each other.

 

28.      Locate and drill the rivet holes to attach the Top Skin Stiffening Angles.  Be sure that they will NOT contact the Bottom Skin Angles or Skin.

 

29.      Locate and drill the rivet holes to attach the Flap Nose Ribs to the Flap Spar.

 

30.      Pre-form the leading edge of the Flap Top Skin by clamping the Skin on a flat surface and rolling up the edge around a large diameter pipe or the rounded edge of a board.  Go slowly as this is only a small smooth bend, not a sharp one.  Locate and drill rivet holes to attach Top Skin leading edge to the Nose Ribs.

 

31.      Dis-assemble, deburr and Dimple the rivet holes in all components.  Prime all Flap Interior surface with zinc chromate.

 

32.          Use the following sequence to assemble and rivet the Flap components:  (NOTE: see instructions on "back riveting")

33.           

           a. Rivet the Spar Doubler, Ribs, and Nose Ribs to the Spar.

           b. Rivet the Stiffening Angles to the Bottom Skin.

           c. Rivet the Bottom Skin to the Ribs, Hinge and the Spar.

           d. Rivet the Stiffening Angles to the Top Skin.

           e. Position the Top Skin and hold in place with Cleco's along the trailing edge.

f. Lift the Top Skin enough to reach the rivet holes in the center rib with a bucking bar,     Rivet the Top Skin to the center Rib.

           g. Rivet the Top Skin to the Spar and end Ribs.

h. Rivet the Trailing Edge Extrusion and Skins.

           i. Roll the Leading Edge over the Nose Ribs and Rivet in place.

           j. Rivet the Hinge to the Center Section Bottom Skin.

 

33.      If you have completed the Flap Handle mechanism now is a good time to fabricate  the Flap Control Tube.  Use the Airfoil Profile boards to set the Flap in the neutral position and measure the distance between centers on the Handle and the Control Arms.  Subtract the length of the bearings to determine the length required for the Control Tube.  Fabricate and install the Tube.  You must get full Flap travel and accurately return to the neutral position.  Make whatever corrections are necessary.

 

34.      This completes the Flap assembly.  Remove the Hinge Pin and set the Flap aside for the remainder of construction.

 

FORWARD FUSELAGE

 

The basis for reference and measurement of the fuselage is the intersection of the horizontal reference plane and the vertical reference plane (centerline) of the fuselage.  This intersection will be called the HORIZONTAL REFERENCE LINE (HRL), and all measurements will be above, below, left, or right, of this reference location.  The HRL is parallel to the WING REFERENCE LINE (WRL) and is located 13.0 inches above the WRL.

 

To simplify measurements and alignment of parts during fuselage construction, the completed Center Section Assembly should be supported in a level position.  This can be accomplished by attaching the Center Section to saw horses and blocking it up as required.  The Center Section support should be firmly attached to prevent movement during construction.

 

The reference line for leveling the Center Section longitudinally is the WRL.  The reference line for span wise leveling is the top surface of the Main Spar.  An accurate spirit level is required. Use the same level, always facing the same direction, for all measurements.

 

1.        After positioning the Center Section in a level attitude, mark a fuselage centerline on the floor of your workshop.  The centerline is established by dripping a plumb bob from the center of the Main Spar and then establishing a line perpendicular to the Spar. This line should extend forward to include Sta. 47.75 and aft to include Sta. 209.5. This line will be used as a reference for positioning the Firewall and Sta.114.75 thru Sta. 209.5 bulkheads.

 

2.        Attach Support Angles P/N 240.455 & .456 and Sta. 73.75 Bulkhead members (P/N 240.331 & -1) to the Center Section Main Spar.  These bulkheads are to be centered at fuselage Sta.  73.75 and are vertical in both planes.  Mark the position of the HRL plane on these bulkheads for future reference.

 

3.        Clamp the formed Fuselage Top Stringer/Channel assemblies in place on the bulkheads.  Position them between Sta. 77.75 and Sta. 99.35 so that the top edge of the stringer is 8.0 inches above the HRL.  A diagonal brace can be clamped between the bulkheads to increase the rigidity of the assembly.

 

4.     Attach the Instrument Panel (P/N 240.320) and the Forward Gusset (P/N 240.401) to the Stringers.  NOTE: The Panel is located at Sta. 71.75 and the Panel is canted forward 7 degrees.

 

NOTE:  The Panel may be mounted vertically for improved gyro performance, if desired.

 

5.        Clamp the right and left Fuselage Forward Skins in place.  Bolt the Engine Mount Brackets to the Firewall and position the Firewall at Sta. 47.75 by clamping it to the fuselage skins and stringers.  See Cowling Attachment section for details on Cowling Attachment strip used at the Firewall.

 

6.        When properly positioned, the center of the Firewall (identified by a 1/16" hole) will be at the intersection of the vertical and horizontal reference planes.  The vertical position of the Firewall is determined in relation to the HRL marks previously placed on the Center Section bulkhead members.  The flat face of the Firewall is to be vertical and perpendicular to the Fuselage Centerline.

 

7.        Drop a plumb bob down the centerline of the Firewall.  It must be directly over the Fuselage Centerline drawn on the shop floor.  Some re-working of the Fuselage Top Stringers may be required to correctly position the Firewall.

 

8.        The forward end of the Fuselage Stringer/Channel assembly should be positioned so that their outer surface is flush with the outer edge of the Firewall.  The Channels can then be riveted to the Engine Mount Attachment Brackets.

 

9.           Position the Fuselage Lower Channels (P/N 240.375 & -1) so that the surface of the Lower Channel is flush with the bottom edge of the Firewall at the front, and with the lower surface of the Center Section Main Spar Cap at the rear.  The inboard edge of the Channel is to be 10.250 inches from the Centerline.

 

10.  Rivet the Lower Channels to the Engine Mount Brackets and to the Center Section Main Spar Attachment Angles.  NOTE: The Firewall Tab is located between the Channel and the Engine Mount Bracket.

 

11.  Temporarily attach Sta. 59.75 Forward Floorboard Support Center Member (P/N 240.379) and the Forward Fuselage Tunnel (P/N 240.394) to the Center Section.  Rudder Pedal Supports (P/N 240.404 & -1) and Rudder Pedal attaching hardware can be attached at this time.  After fitting the Tunnel, it should be removed to facilitate the Side Skin installation.

 

12.      The shape of the Forward Fuselage Side Skin at the forward end is determined by the contour of the Firewall Bottom corner. The bend of the Side Skin at the junction with the lower surface of the Main Spar is a 1" radius.  To insure a good fit make a cardboard pattern for the cut-out in the area of the Center Section Spar.  The Fuselage Side Skin should be close to but, NOT touching the Center Section Spar.  Pre-forming the skin forward of the Spar would be helpful.

 

13.      The bottom edge of the Side Skin aft of the Firewall is trimmed flush with the edge of the Tunnel opening to Sta. 60.25. At this point the skin joggles outward .625" to allow flush installation of the Forward Fuselage Belly Skin.

 

14.      The Side Skin is attached to the Fuselage Lower Stringer (P/n 240.370) so that it is close to but, NOT touching the Center Section Top Skin aft of the Main Spar.

 

15.      Trim the top edge of the Side Skin flush with the top edge of the Fuselage Upper Stringer for its entire length.

 

16.      The aft end of the Side Skin terminates at the center line of Sta. 114.75 Vertical Bulkhead member.  The lower edge of the Side Skin, aft of the Rear Spar, is trimmed to 1/16" above the Flap in the full-up position.

 

17.      After the two Side Skins have been fitted and trimmed, they may be riveted to the structure (see items 17 & 18 below). Use AN 470 AD4 rivets for attaching the skin to the Lower Stringers aft of Sta. 73, and to the Center Section Spar lower surfaces. Use AN 426 AD4 rivets for all other Side Skin attachments.  All rivet spacing, from Sta. 114.75 forward, is to be 1" unless specified otherwise.  See the detail on drawing 240.008 for attaching the Side Skins to the Fuselage Top Stringers.  The Stringers must be countersunk and the skin dimpled per the drawing.

 

18.      To eliminate an unsightly skin joggle at the aft end of the Fuselage Side Channel, a Filler Shim (P/n 240.405) is installed between the Skin and Stringer.

 

19.      Use only a few rivets, at this time, to attach the Side Skins where the installation of the Fuselage Forward Top Skin will overlap the Side Skins forward of the Instrument Panel.

 

20.      The Fuselage Sta. 59.75 Bulkhead members (P/N 240.379, 380 & 380-1) may now be installed.  The Forward Tunnel (P/N 240.394) and Forward Belly Skin (P/N 240.395) may also be attached.  NOTE: Some builders delay riveting the Belly Skin in place until later as his opening provides good access for working behind the Instrument Panel and for installation of the Brake components.

 

21.      Two Skin Stiffeners (P/N 240.371 & 378) are attached to the Belly Skin at Sta. 2.625 right and left.

 

22.      The Fuselage Forward Section Skin Stiffening Stringers (P/N 240.371-1, -2 & -5) are now installed.  Use AN 426 AD3 rivets to attach these and all other 240.371 series Stringers using a 2" spacing.

 

23.      Attach the two Roll Bar Assemblies (P/N 240.203 & -1) per drawing 240.016.  Use AN 470 AD4 rivets.

 

24.      The Center Section Leading Edge Ribs at Sta. 20.0 are riveted to the Fuselage Side Skins by means of one row of AN 470 AD4 rivets on 2" spacing, located 1/2" below the top edge of the Rib and extending as far forward of the Spar as the Fuselage contour will permit.

 

25.           Position and assemble the Fuselage Top Channel (P/N 240.377) and the Engine Mount Attachment Bracket.  The Fuselage Forward Top Skin (P/N 240.393) can now be fitted but NOT attached.  The Fuel Tank, Fuel Filler door, all Firewall fittings, and fresh air vents should be completed before attaching the Top Skin.

 

26.      Install the two Top Auxiliary Channels (P/N 240.378) and the Fuselage Auxiliary Formers (P/N 240.381 & -1).  Make cardboard patterns of the fuselage to use as templates for the Auxiliary Formers.

 

27.      Install the two Seat Back Attachment Brackets (P/N 240.302) to the Fuselage Top Stringers.  NOTE: The forward edge of these brackets is Sta. 102.5.  These brackets are used only if you intend to use the Seats detailed in the plans.

 

28.           Position the Fuselage Sta. 114.75 Bulkhead Assembly and rivet it to the Fuselage Side Skins.  When properly positioned the bulkhead assembly will have its Vertical Center Line directly over the center line drawn on your shop floor.  Its HRL will align with the HRL marks on the other bulkheads. It is wise to use jigging to hold the Fuselage Sta. 114.75 Bulkhead assembly steady while installing the remaining Forward Fuselage components.  NOTE: The Forward Fuselage Side Skins extend to the center line of the Sta. 114.75 Bulkhead so that the Tail Cone Skins can butt against the forward skins.  NOTE:  Make certain that the bottom member of the Sta. 114.75 Bulkhead does NOT prevent the Flap trailing edge from returning to the full up position.

 

29.      The two Baggage Floor Support Angles (P/N 240.421 & -1) are now installed.  It will be necessary to form a joggle at the forward end of these Angles for clearance of the Fuselage Stringers (P/N 240.370).j  An alternate method is to install a .065" shim between the Angles and the Side Skin.  Use AN426 AD4 rivets, on 2" spacing, to attach the Angles to the Side Skins.

 

30.      The Baggage Floor (P/N 240.420), Baggage Floor Supports (P/N 240.422), and the two Control Tunnel Angles (P/N 240.408) may now be riveted in place.

 

This completes the Forward Fuselage Assembly.

 

FUEL TANK

 

The Mustang Fuel Tank is fabricated per drawings 290.003, and 004, or, it may be purchased from Mustang Aircraft.  The Tank is designed to utilize standard Cessna fittings for filler cap and sending unit.

 

The attached sketch shows the basic layout of the Fuel System components.  The actual installation instructions are covered in the plans and will not be detailed here, but there are some rules that must be followed when installing your fuel system.

 

1.        The Fuel Tank Vent Line MUST be routed FORWARD over the top of the Tank.  DO NOT route it downward, or, over the back of the Tank.  Flight motions and gravity force fuel to surge to the back of the tank, which would force fuel out of the Tank.  By routing it forward, the Vent Line remains open.

 

2.        On engines of LESS than 320 CID, with the newer type Marvel Schebler carburetor, the forward facing Vent Line may be eliminated.  The new carburetor incorporates a revised venting system.  On engines GREATER than 320 CID, a forward facing Vent Line is required.  The forward facing vent may be eliminated if the system includes a fuel pump.

 

3.        The Fuel Gascolator/Drain is located at the lowest point in the Fuel Line and forward of the Firewall.  The Gascolator must NOT be located near the Exhaust system  or, any other heat source and should not extend below the lower edge of the Firewall.

 

4.        A collar MUST be fitted around the Fuel Filler Neck to catch any spillage during fueling.  It should extend from the top surface of the Tank up to the surface of the Fuselage Skin.  A drain can be incorporated in the collar to permit spillage to drain out of the aircraft.  It must be sealed to both surfaces with a compound that is not effected by fuel.  NOTE:  This collar should be made of flexible material to permit the Fuel Tank to expand or contract.

 

5.        A Water Separator, a standard Gascolator will do, should be incorporated in the Fuel Tank Vent Line if flight in raining conditions is expected.  It should be mounted forward of the Firewall, located in a spot that is convenient for inspection during your Pre-Flight checks.  All water MUST be drained prior to flight.

 

6.        Do NOT rely on the engine driven Fuel Pump as your only means of delivering fuel to the engine.  The Mustang II Fuel Tank is well above the carburetor and is in a suitable location to install a Gravity Feed System.  If the engine driven fuel pump is used, an auxilliary electric pump must also be installed.  Make certain that the fuel selector valves used in your installation are clearly labeled for their open and closed positions and include labels to indicate which pump is used.  Placard your fuel system.

 

                      (GRAVITY INSTALLATION)

 

1.           Forward facing Fuel Tank Vent - 1/4" alum. tubing.

2.        Fuel Tank Filler Cap - Automatic Venting - Cessna     P/N C-156003-0101

3.        Fuel Overflow Collar - fuel proof w/overboard drain

4.           Fuselage Skin

5.        Fuel Tank - 25 Gal.

6.           Number 800 Finger Strainer - 20 mesh.

7.        AN 911-2D Nipple                                                       (911-3D)

8.        AN 914-2D Elbow  (914-3D)

9.        Two position Fuel Selector Valve - 1/4" thread (3/8")

10.      AN 816-6D Nipple  (816-8D)

11.      3/8" OD seamless aluminum tube with AN 818      & 819 Flare Fittings  (1/2"OD)

12.           Firewall Fitting - AN 833-6D  (833-8D)

13.      Fuel Strainer With AN 822-6D fittings  (822-8D).  Includes Fuel Drain Cessna P/N 0450246  (0756005-1)

14.           Flexible Fuel Line - Aeroquip 303-6  (303-8) with 421 fittings.

15.           Carburetor

16.           Firewall

17.      Water Separator - Glass type automotive fuel filter or aircraft gascolater.

 

NOTE:  Items in parentheses are to be used if engines of 360 CID,or larger, are installed.

 

This completes the Fuel Tank

 

MUSTANG FUEL SYSTEM

 

1.        Fuel tank vent line MUST be routed forward over top of tank to firewall area.  DO NOT route vent line downward at rear of tank.

 

2.        Fuel vent line may be modified to eliminate forward facing            ram air pick up on engine installations of less than 320 C.I.D. when newer type Marvel Schebler carburetor incorporating revised venting system is installed.

 

3.        Fuel gascolator/drain to be located at lowest point in fuel line and on forward side of firewall.  Gascolator must not  be located near exhaust pipes or other heat source.

 

4.        A builder fabricated retaining device around the fuel tank. filler is to be installed to contain fuel spilled during filling operations.  A foam and fiberglass filler around the fuel tank filler neck, extending from tank top to top skin of fuselage is suggested.

 

5.        If flight in rain conditions is anticipated a water separator is to be incorporated in the fuel tank vent line.  For convenience of inspection the unit should be mounted on forward side of firewall in a position that is visible for preflight inspection through cowling oil access door.  All water must be drained before flight.  A standard aircraft gascolator with quick drain, and required mounting is suggested.  See accompanying sketch.

 

FUSELAGE TAIL CONE

 

The Tail Cone consists of the Fuselage structure aft of Station 114.75.  The bulkhead members are fabricated of .032" 2024-T3 aluminum, and the Skin pieces are of .025" 2024-T3 aluminum.  All skin attachment rivets are AN 426 AD4-4-4.  All rivet spacing is 2" unless specified otherwise (skin & bulkheads).  NOTE: Use 1" rivet spacing on Bulkhead Sta.  114.75 below the Top Stringer.

 

The Tail Cone is constructed directly onto the Forward Fuselage structure.  The same reference marks (HRL, VRL & Centerline) used during the construction of the Forward Fuselage are used for the Tail Cone construction.

 

1.        Begin the Tail Cone construction by positioning Fuselage Sta. 209.5 in relation to the HRL and center line.  To facilitate alignment of Sta. 209.5 Bulkhead, the Vertical Fin Spar (P/N 250.331) should be attached to the bulkhead.  See Empennage sect.

 

2.        Align the Bulkhead and Fin Spar assembly vertically on the center line using a plumb bob, and located so that the Bulkhead HRL coincided with the Forward Fuselage HRL.  To facilitate working with Fuselage Sta. 209.5 and Fin Spar assembly, a vertical support should be constructed extending from the floor to the ceiling (see photo's).  The vertical support should be spaced approximately 2" aft of the assembly for ease of working. This can be done using suitable spacers and clamps but, they should be located no closer then 4" above the HRL.

 

3.        Form the Tail Cone Belly Skins (P/N 240.391 & -1) from .025" aluminum per drawing 240.015.  Clamp these Skins in position on Sta. 114.75 Bulkhead and Sta.  209.5 Bulkhead.  NOTE:  Tail Cone Doubler  (P/N 240.423)  is installed NOW if you wish to have it inside of the Skins.  See step 13.

 

4.        The Belly Skins should be supported during the balance of construction to provide a stable working base.  This can be accomplished by using a sheet of 1/2" plywood supported by saw horses.  Cut the plywood to the shape of the Belly.  Later this will enable you to use straps to pull the Side Skins down into place against the Bulkheads.  NOTE:  The plywood base will not interfere with using Cleco skin fasteners if the holes are drilled from the inside.

 

5.        Form the Fuselage Sta. 194.609 Bulkhead (P/N 240.355) per drawings 240.021 and 250.007.  This Bulkhead is formed on a wooden forming block (see Appendix).  Forming of the inner flange is a stretching operation so the edge must be free of nicks or scratches, and preferably polished.  Forming will be easier if the inner flange height is dept to a minimum.

 

6.           Fabricate Bulkhead Doubler (P/N 240.348) per drawing 240.025 and attach it to the Fuselage Sta.  194.609 Bulkhead using AN 470 AD4 rivets.

 

7.        The joggle, or offset, at the top of the Bulkhead is for attachment of a 1-1/4" wide .025" aluminum strip to provide for a flush installation of the Fin Fairings.  This strip is to be fabricated at the time of assembly to fit the Fuselage contour. NOTE:  This contour will be determined by the actual slope of the Side Skins, therefore, fit the strip when fitting the Skins.

 

8.        Form Fuselage Sta. 187.5 Bulkhead (P/N 240.335) per drawings 240.021 and 240.023, and in the same manner as Sta. 194.609. NOTE:  The plate nut used for Fin attachment and the clearance slot for the Side Skin Flange are located on the LEFT side of the aircraft.  Offset to the LEFT is .250".

 

9.        The plate nuts for the Forward Stabilizer attachment may be installed at this time, however, a more precise alignment is possible if they are installed at the time of Stabilizer construction.  See the Stabilizer section for more information.

 

10.      The Fuselage Sta. 187.5 Bulkhead is now positioned on the Tail Cone Belly Skins.  Drill the rivet holes and fasten using ONLY Cleco fasteners.  This Bulkhead contains the Fin and Stabilizer attachment points so it must be located accurately.

 

11.      It may be necessary to use shim strips of 1/2" wide aluminum between the Bulkheads and the Skins to achieve a proper fit. Clamp braces from each side, near the top of the Bulkhead, down to the Belly Skins to hold the Bulkhead in position.  NOTE: Fuselage Sta. 209.5 may need re-adjustment at this time.

 

12.      The Tail Cone Belly Skins can now be riveted together. Rivet spacing is 2" using AN 426 AD4-4 rivets.

 

13.           Fabricate the Tail Cone Doubler (P/N 240.423) per drawing 240.019.  This Doubler is fitted to the outside contour of the Tail Cone.  The purpose of the Doubler is to reinforce the Tail Wheel Spring attachment and may be omitted on tri-gear models. NOTE:  To obtain a "cleaner" appearance the Doubler may be installed on the inside of the Skins.  This is slightly more complicated to fit.  If the inside installation is used the Doubler must be located in p[position PRIOR to fitting the Belly Skins at Sta. 209.5

 

14.      Use the following procedure to align the Bulkheads, Sta. 194.609 and Sta. 209.5:

 

Tightly stretch a fine wire from the top center line of Fuselage Sta. 114.75 Bulkhead to the center line of the Fin Spar. Position the wire vertically so that it just touches the top of Sta. 187.5 Bulkhead.  This wire will be used as the reference line for positioning all the Tail Cone Bulkheads.

 

15.           Position Fuselage Sta. 194.609 Bulkhead and attach it to the Belly Skins with Cleco fasteners.  NOTE:  This bulkhead rotates forward 1 1/2 degrees.  This coincides with the 1 1/2 degree negative angle  of incidence of the Horizontal Stabilizer.

 

16.           Fabricate Fuselage Sta. 205.0 Bulkhead (P/N 240.336) and its related Tail Wheel Support sub-assemblies per drawings 240.021, 023, 025, and 007.

 

17.           Position Fuselage Sta. 205.0 Bulkhead and attach it to the Belly Skins using Cleco fasteners.  NOTE:  This Bulkhead also rotates forward 1-1/2 degrees, similar to Sta, 194.609.  To permit adjustment drill the rivet holes only in the Belly Skins.

 

18.           Fabricate the Horizontal Bulkhead (P/N 240.356) per drawing 240.026 and Horizontal Bulkhead (P/N 240.345) per drawings 240.021 and 023.

 

19.           Position the two Bulkheads between Fuselage Sta.  209.5, Sta. 205.0 and Sta. 194.609.  The top edge of the aft Horizontal Bulkhead is located on the HRL.  The top edge of the forward Horizontal Bulkhead is aligned at the aft end with the top edge of Sta. 205.0.  The lower edge of forward end is aligned with the lower edge of the Doubler installed on Sta. 194.609  Bulkhead.  NOTE:  This positions the forward Horizontal Bulkhead lower at the front.  This is necessary to provide clearance for the Horizontal Stabilizer.  Check the alignment of the vertical Bulkheads and rivet the Horizontal Bulkheads in place.

 

20.      Fit the Fuselage Skin Stiffener Stringers (P/N 240.371-6 and 371-7) and rivet in place between the Bulkheads.

 

21.           Fabricate Fuselage Sta. 162.0 and 138.0 Bulkheads (P/N 240. 205 and 206) per drawings 240.021 and 22.  NOTE:  Because of variations in the construction of the Bulkheads at Sta. 114.75 and Sta. 187.5 the actual dimensions for Sta 162.0 and Sta. 138.0 may differ from the blueprint dimensions.  To determine the actual width required, lay out their locations on the Belly Skin assembly and measure the actual width.

 

22.           Assemble the Bulkhead Side and Bottom members to the above measurements on your workbench.  The Bulkhead Top Members are NOT attached at this time although, they may be clamped to the Bulkheads to help hold their shape.

 

23.  Position the Bulkhead assemblies on the Belly Skin but, do NOT drill the rivet holes as it may be necessary to move the Bulkheads forward, or aft, to achieve good contact with the Side Skins.  Once a good fit is achieved the Bulkheads may be riveted to the Belly Skin.

 

24.      If the dimensions of your Battery Box are known then position and rivet the Battery Mounting Channels (P/N 240.411 and -1) in place.  If you do not know these dimensions these parts may be installed later.

 

25.      All riveting of the bottom portion of the Belly Skins should now be completed.  Re-Check the alignment of each Bulkhead, do NOT rely on the Cleco fasteners to hold their position during riveting.  Sight down the top and sides of the Bulkheads to maintain a "true" fuselage line.  Any discrepancies here will be magnified when the Side Skins are installed.

 

26.      Clamp the Top Members of Fuselage Sta.  162.0 and Sta. 138.0 Bulkheads into position.  Sight down the tight wire to make sure that they are centered.

 

27.  Clamp Fuselage Stringers (P/N 240.390 and -1) to the Bulkheads.  These Stringers will help to hold the Bulkheads in position.

 

28.      Stretch additional wires from the top outer corners of Fuselage Sta. 114.75 to Sta. 187.5 Bulkhead.  These wires will aid in the alignment of the top sections of Fuselage Sta. 162.0 and 138.0 Bulkheads.  Again, a small error will be magnified when the Skins are installed.

 

29.      Rivet in place the Top Members of Fuselage Sta. 162.0 and           sta. 138.0 to their Side Members.

 

30.      Shape the Tail Cone Side Skins (P/N 240.390 and -1) per drawing 240.015.  Leave the Skins oversize at the ends for easier fitting.  They can be trimmed after fitting.

 

31.      Pre-form the Skins on your workbench by clamping 2x2 wood pieces to the edge which will be the center line, and gently bend to shape.  Use care so as not to crease the metal at the edge of

 

32.      Start with the Right Side Skin.  Position the Skin.  Drill the rivet holes along the top edge, and hold in place with Cleco fasteners.  Work down and across all bulkheads evenly to prevent buckles or waves.  Clamp the bottom edge of the Skin to the bulkheads using a 2"x2".  This will prevent waviness at the seam along the Belly Skin.  The 2" rivet spacing may be altered to accommodate the taper of the curved areas.  Use as many Cleco fasteners as necessary to hold the Skin "true" while drilling.

 

33.      Once all rivet holes are drilled, remove the Skin, trim it to the exact shape, clean the chips, and dimple the rivet holes. It may now be riveted in place.  It is wise to repeat step 32. for the Left Skin before riveting either Skin in place.  This will permit you to alternate between the Right and Left sides during riveting to avoid pulling the Tail Cone out of alignment.

 

34.      Using only two Skins for covering both the sides and top, results in the need to install a Tail Cone Vertical Fin Fairing. It may be installed now, or, after both skins are in place. Shims may be necessary for a proper fit.

 

CONSTRUCTION NOTES:  The rivet locations on the Bulkheads can be located either by drilling from the inside, or, by measuring using the technique described for the installing the Wing Leading Edge Skins.

 

If the edges of the Side Skins are left slightly high between Fuselage Sta. 194.609 and Sta. 205.0 when installed, they can later be trimmed to the exact contour of the Horizontal Stabilizer surface.  This will eliminate the need for a separate fairing in this area.

 

Trial Fit the Tail Wheel Bracket (see drawing 270.006 for detail) and make any adjustments before riveting the skins in place.  Any attachment angles required for tail wheel steering should be] fitted in place.

 

There is an Inspection Hole in the aft right side skin.  See the Empennage section for best location of this hole.  Cut the opening and make a flang and fit a cover.  The cover will be held in place with plate nuts.  This is easier now, before the Skin is permanently in place.

 

Give some thought to the need to run any wiring, the location of the battery, and corrosion protection before closing the Tail Cone Skins.  It is easier to work while the Skins are open.  This completed the construction of the Fuselage Tail Cone.

 

This complete the Tail Cone

 

HORIZONTAL STABILIZER

 

1.        Form the Ribs from .025" 2024-T4 aluminum over forming blocks as described in Appendix Note 1.  Form the Spars per the drawings.

 

2.           Connect the two Rear Spar sections P/N 250.301 together by riveting on the two Rear Spar Reinforcements P/N 250.302, making certain to align the center lines.

 

3.        Attach the two .125" x 3/4"x4" 2024-T3 strips to the outside surface of the top and bottom Rear Spar flanges at the center. These pieces reinforce the Spar splice and also act as Elevator Stops.  Elevator travel is adjusted by varying the width of these pieces.

 

4.        Attach the outboard Stabilizer Hinge anchor nuts and Spar Doublers, and drill the center Hinge attachment holes as detailed on drawings 250.001 & 250.003.  Be certain to use liberal amounts of zinc chromate primer between the aluminum and steel fittings.

 

5.           Position the Rear Spar on the Fuselage Attachment Brackets (P/N 250.307) and bolt in place.  Be certain that the Rear Spar is centered in relation to the Fuselage center line and is level laterally.  This is done with a level, using the Rear Spar center line as the reference.  NOTE:  The Rear Spar has 1-1/2 degree Negative angle of incidence which determines the attachment points for the Stabilizer Front Spar and Leading Edge attachment bolts.

 

6.  Verify that the Fuselage HRL is in a level attitude before proceeding.

 

7.        To determining the forward attachment points, run a line from the center line of the Rear Spar forward at a negative angle of 1-1/2 degrees.  With this line established, the attachment points are located where this line intersects Fuselage Sta. 194.609 and Sta. 187.5  The center line of the Front Spar location is on the line at Sta. 197.609 and the Attachment Bolt location is on the line at Sta. 187.5

 

8.           Fabricate the Stabilizer Front Spar (P/N 250.303) per drawings 250.001 and 003.  See drawing 250.007.

 

9.        Clamp the Front Spar in position on Bulkhead Sta. 197.609 noting that it lines up with the center line of the Bulkhead and is level laterally.

 

10.      With it clamped into position, the Spar Attachment Bolt holes can be drilled through the Spar and the Bulkhead in one operation, thus assuring proper alignment.  After the holes have been drilled, the plate nuts can be riveted in place on the Bulkhead.

 

11.      The Stabilizer Root Ribs (P/N 250.304) can be installed either in one, or two pieces.  They are attached to the Spars by means of Angle Clips (P/N 250.365).  See drawing 250.001.  NOTE: If the Ribs are fitted in one piece, cut a rectangular opening so that the Forward Spar can pass through.  This method eliminated the difficulty of fitting the Ribs in two pieces.  An Angle Clip is used to attach the Ribs to the Spars whatever method is used.

 

12.      Attach the Forward Attachment Brackets to the leading edge of the Root Ribs.  Coordinate the position of the attachment bolt hole with Sta. 187.5 Bulkhead.  Don't forget the zinc chromate primer.

 

13.           Assemble the Ribs onto the Stabilizer Spars and Fuselage Bulkhead.  The tip Ribs (P/N 250.305) are installed in one piece. Verify that the Tip Ribs are set to the Negative 1-1/2 degree incidence.  NOTE:  Due to variations in measurements and metal bending, you may find that a shim is necessary between the sections of the Root Ribs and the Spars, or between the Stabilizer Spar and the attaching Bulkheads.

 

14.      Install the Outer Stabilizer Hinge fittings (P/N 250.308) at this time, if they were not installed when assembling the Rear Spar.

 

15.      You are now ready to attach the .032" 2024-T3 Stabilizer Skins (P/N 250.306).  See the Appendix Note #5 for details on forming the leading edge radius in the sheet metal.  NOTE:  The Stabilizer Skins have extensions which extend through the Fuselage area.  It will simplify the construction if these extensions are omitted from the primary skins.  These pieces will be installed when you rivet the skins to the Root Ribs.  These extensions have an access opening cut in them to permit reaching the Forward Spar attachment bolts.  There is also an access opening in the Fuselage Side Skin to permit reaching the Stabilizer Rear Spar attachment bolts.

 

16.      Cut the Skins somewhat oversize to allow for trimming at the Fuselage.  The Stabilizer Skins can be carefully cut to fit at the inboard end, eliminating the need for a fairing piece.

 

17.      Clamp the formed Skin in place on the Forward and Rear Spars.  At this point you will find that the Stabilizer is easily twisted especially at the Tip Rib on the Forward Spar. Therefore, before drilling any rivet holes, CHECK the angle of incidence of the Tip Rib.  It must match the 1-1/2 degree negative incidence of the Root Rib.  To guard against mis-alignment it is advisable to clamp a support extending from the floor to the leading edge of the Tip Rib to maintain its position.  Use as many clamps and supports as necessary to hold the incidence BEFORE drilling the rivet holes.

 

18.      If the extensions were left on the Stabilizer Skins it will be a bit more difficult to clamp in the root area.  A 3/32 Cleco fastener into the Root Rib should hold it while the Skin is aligned.

 

19.      With the Skin properly aligned and clamped in place begin drilling the rivet holes.  This is best done by first drilling the holes in the Forward Spar.  The location for the holes is determined by measuring the distance, under the Skin, from the rear edge of the Skin to the Forward Spar Webb.  This measurement is then transferred to the top side of the Skin and used to determine the center of the Forward Spar flange.

 

20.      Drill all of the rivet holes in the Forward Spar and Cleco the Skin in place.  Remove some of the clamps as you proceed to check that the Skin is "true" and that the angle of incidence is still set.

 

21.      Next drill the rivet holes in the Ribs between the Forward and Rear Spars.  Watch that a bulge does not develop in the middle of the Rear Spar.  Use a 2x2 securely clamped along the Rear Spar to prevent a bulge.

 

22.      Next drill the rivet holes in the Ribs forward of the Spar to the leading edge.

 

23.           Following the same steps, the rivet holes are now drilled in the bottom surface of the Stabilizer.

 

24.      If the Skin extensions were omitted earlier, they should now be fitted in place.  Make up the required piece of .032" metal for the top and bottom extensions, with inspection holes, and insert them under the Stabilizer Skin, between the Skin and Rib. This will permit transferring the hole pattern already drilled in the Skin.  NOTE:  When finally installed there will be no seams visible on the outside of the aircraft.

 

25.           Remove the Skin for deburring and dimpling of the rivet holes.

 

26.      Re-assemble the Stabilizer components using Cleco fasteners. Re-check the Negative 1-1/2 degree incidence angle.

 

27.      The following riveting sequence will prevent mis-alignment of the structure and eliminate the hard to reach rivets:

 

           a.  Install all  rivets in the top flange of the Rear Spar

           b.  Install all rivets in the Tip Rib top Flange.

           c.  Install only the rivets forward of the Front Spar in the bottom flange of the Tip Rib.

           d.  Support the Tip Rib and remove all the Cleco's from the bottom Skin AFT of the Front Spar.  This will permit flexing the Skin down enough to rivet the Skin to the Front Spar top and bottom flange.           Start with the top flange.

           e.  Re-attach the bottom Skin to the structure with Cleco's and complete the riveting of the Tip Rib and Rear Spar            lower flange.

           f.  Remove this assembly from the Fuselage and complete the riveting of the Root Ribs.  The Stabilizer assembly is sufficiently rigid at this point to prevent any change in alignment during this riveting.

 

27.      The Fiberglass Stabilizer Tips will be installed after the

Elevators are completed.

 

This completed the Horizontal Stabilizer Assembly.

 

VERTICAL FIN

 

1.        The Vertical Fin Rear Spar (P/N 250.331) is constructed during the Tail Cone construction process to aid in positioning Fuselage Sta. 209.5.  It is constructed per drawing 250.004. See Fuselage Sta. 209.5  Bulkhead installation instructions for positioning the Fin Spar.

 

2.        Run a line from the center line of the Fin Rear Spar forward to the center of Fin Forward attachment plate nut on Fuselage Sta., 187.5 Bulkhead.  Mark the point where this line crosses the Sta. 194.6 Bulkhead.  This will be the center line of the Fin Forward Spar.

 

3.        Attach the Fin Bottom Rib (P/N 250.334) to the Fin Front Spar (P/N 250.333).  Cleco this assembly in place on the Fin Rear Spar and determine the location of the Fin Rib Forward Attachment Bracket.  It may be necessary to use a shim between the steel fitting and the Rib flange as it may be necessary to relocate the Bracket to align with the plate nut in the Sta. 187.5 Bulkhead. Remember to use zinc chromate primer on all of the steel parts.

 

4.        Rivet the Fin Bottom Rib (P/N 250.335) and the Forward Rib Attachment Bracket in place.  NOTE:  The Fin Forward Spar is NOT yet riveted in place.

 

5.           Position the Fin Top Rib making sure that it aligns with the Fin Bottom Rib.  NOTE:  The leading edge of the Vertical Fin is offset to the LEFT, maintain this offset when installing the Top Rib.

 

6.        Rivet the Fin Top Rib in place.

 

7.        Attach a temporary gusset to the lower section of the Fin assembly to hold it rigid.  The location of the Fin Forward Spar Attachment Brackets (P/N 250.362 and -1) can now be determined.

 

8.        The Brackets are clamped to the lower end of the Fin Forward Spar and positioned to be against the Fuselage Sta. 194.609 Bulkhead.  This will permit drilling the holes through the Sta. 194.609 Bulkhead and the Fin Forward Spar Brackets in one operation.

 

9.        The Vertical Fin Skin (P/N 250.330) may now be fitted to this structure in the same manner as was used for the Stabilizer Skins.  NOTE:  The Vertical Fin is OFFSET to the left, maintain this alignment in the Fin Top Rib.  This can be done by sighting from the front of the fuselage.

 

10.      The Vertical Fin Skin should be cut oversize to permit fitting the bottom edge to the fuselage contour forward of Sta. 194.609.  NOTE:  A gap of 1/16" should be allowed between the Empennage Skins and the Fuselage Skins to prevent chaffing.  A rubber chaffing strip should be installed so that the Skins do not rub against each other.

 

11.      A fiberglass Fin Tip will be fitted after the Rudder installation is complete.

 

This completes the construction of the Vertical Fin.

 

CONTROL SURFACE CONSTRUCTION

 

The following Sections detail the construction of the Control Surfaces and describes the method for forming the Skins.  See Appendix Note #10 for additional information.  It is necessary to drill fatigue relief holes in the trailing edge of the formed skins.  Drill a size #40 hole, about 1/2" from each end of the trailing edge radius, in the formed skins.  This will prevent a crack from spreading should one develop.

 

ELEVATOR CONSTRUCTION

 

1.           Fabricate the Elevator Spar (P/N 250.315) and Rib assemblies per drawings 250.002 and 003.

 

2.        Use the steel Elevator Attachment Bracket (P/N 250.314) as a gusset to attach the Inboard Ribs to the Elevator Spar.  NOTE: The right Inboard Rib is modified for the installation of the Elevator Trim Tab.

 

3.        Clamp the Elevator Control Horn (P/N 250.322) and the Center Hinge Assembly (P/N 250.309) to the Fuselage in a neutral position.

 

4.        The Elevator Spar is now fitted to the Control Horn and Hinge Assembly.  This is done ON the aircraft so that the Elevator attachment to the Control Horn assembly can be adjusted in length.

 

5.  Cut the Elevator Control Attachment Bracket Tube (P/N 250.312) to length, allowing for the thickness of the Attachment Bracket (P/N 250.313) between the Tube and Elevator Control Horn assembly.

 

6.        Once this dimension is determined, the Attachment Bracket can be welded to the Elevator Tube.  This eliminates the need for shims when the Elevator and Control Horn assemblies are mated. NOTE:  A steel shim is permitted to achieve a good fit.

 

7.        After adjusting and completing the assembly of the Elevator Spars and Control Horn mechanism, the Elevator Skins (P/N 250.316) can be formed.  NOTE:  The right Elevator Skin contains the Trim Tab.

 

8.        The Skin trailing edges are formed in a bending brake.  Mark two bend lines at each edge of the skin that are 1/8" on each side of the center line of the trailing edge.  Insert the Skin into the brake with the edge of the top metal hold down aligned with the first bend line, ie. the centerline and the second bend line are exposed.  Make a 60 degree bend in the skin.

 

9.        Turn the skin around and insert the skin so that the other bend line is under the brake hold down.  Bend the Skin again, going as far as the bending brake will allow.

 

10.      To complete the bend of the trailing edge remove the Skin from the brake and insert this formed trailing edge under the brake hold down.  The brake used for this operation should have at least a 2" opening.  NOTE:  The trailing edge tapers from the root to the tip therefore, you will be pulling the brake lever only at one end of the brake.  Gently pull the lever to squeeze the trailing edge to a sharper radius.  See Appendix Note 10.

 

11.      The Elevator leading edge bends may now be formed.

 

12.      Mark the location of the Elevator Spar on the inside of the Skin and proceed to attach the Skin Stiffening Angles.  NOTE: Make sure that the vertical leg of the Angles taper sufficiently so that they do not contact the opposite Skin surface and cause a bulge.

 

13.           Position the Elevator Skins on the Spar Assembly and drill the rivet holes.  NOTE:  CAUTION, make certain that the Elevator does not incorporate a twist.  The trailing edge of the Skin must be in alignment with the center line of the Spar.

 

14.           Fabricate and install the Elevator Trim Tab assembly at this time.  See drawing 250.009.

 

This completes the construction of the Elevators.

 

RUDDER CONSTRUCTION

 

1.           Fabricate the lower Rudder steel components (P/N 250.345) per drawings 250.005 and 006.  This includes the Rudder Bottom Rib(P/N 250.342), the Rudder Stop Assembly (P/N 250.348), and the Tail Wheel Steering Bracket (P/N 250.349).

 

2.  Complete all welding of the Cable Attachment Brackets (P/N 250.346) and the Lower Hinge Fitting (P/N 250.347).  Thoroughly zinc chromate all steel parts.

 

3.        Attach this assembly to the Rudder Spar Assembly (P/N 250.341.  NOTE:  The AN 366-632 plate nuts used to attach the Lower Fairing to the Rudder Lower Rib and on the Rudder Lower Spar Section may be replaced with Monel "pop" rivets, if desired.

 

4.        Match the Rudder Upper Hinge Fitting (P/N 250.348) to the Upper Fitting on the Vertical Fin and rivet in place.

 

5.        The Rudder Skin (P/N 250.340) is formed in the same manner as described for the Elevator Skins.

 

6.        The Rudder Top Rib (P/N 250.343) and Skin Stiffeners are attached to the Rudder Skin.  The Rudder Skin is installed in the same manner as the Elevator Skins were installed.  NOTE:  Make certain that the Rudder trailing edge is aligned with the center line of the Rudder Spar.

 

7.        With the Rudder, Fin, Stabilizer, and Elevator in place, the fiberglass Tip Fairings may now be installed.  Fit these parts so that there is a smooth transition from the fairings on the Fin and Stabilizer to the fairings on the Rudder and Elevators.

 

8.        Finally, make certain that there is NO BINDING in any of the

control surface hinges.  The surfaces must move freely. Lubricate the hinges with WD-40, or Silicone spray, to keep them free.  Any binding or flexing of the Spar Webb will cause cracking and possible failure.

 

This completes the construction of the Rudder.

 

CANOPY INSTALLATION

 

The Mustang II Canopy may be purchased from:

           Mustang Aeronautics - Rounded style as shown in plans

           Mustang Aeronautics - Squared off Thorp T-18 style

 

Remember that the Canopy should fit snugly to prevent excess wind noise in flight and that it keeps the rain out of your cockpit. With these factors in mind, fit all fairings and sealant compound carefully.  Also, remember that the Canopy framework and joints will be subjected to very high pressures during flight.  Make sure all fittings are secure, with a minimum of fairing edges exposed to the airflow.  This will also produce a "cleaner", drag free, aircraft.

 

The plexiglass Canopy may be trimmed in a number of ways, each with its own concerns.  First, do not work on cold plexiglass, a temperature above 70 degrees is preferred.  You may use a power woodworking router with a 3/16" or smaller bit, a saber saw with a hollow ground saw blade, or, a Norton Abrasive Cutting Wheel (A60-OBNA2) mounted in your electric drill.  The router cuts quickly and cleanly, but, is somewhat difficult to control in the curved areas.  The saber saw is easier to control, but, the blade may overheat or cause cracks if it binds.  If you use a saber saw Go Slowly.  The abrasive cutting sheel is a flexible 3" wheel that does a nice job, even on metal but, care must be used not to break the wheel.  If you use the cutting wheel method wear eye protection and have spare wheels on hand.  Finally, a belt sander, with fine paper, is used to finish the edges after cutting.  There are some areas along the edge of the canopy that are best done only with the belt sander.  Like aluminum, all prevent cracking.

 

CANOPY FRAME CONSTRUCTION

 

The construction of the Canopy Sliding Frame must be coordinated with the contouring of the plexiglass canopy to obtain a proper fit.  CAUTION:  Do not put the canopy on the framework while it is still hot from welding.  The heat may damage the plexiglass.

 

The Canopy Frame and Sliding mechanism is constructed per assembly drawings 280.002 and 003.  These assemblies must be fitted to your canopy at the time of construction.

 

A Gusset, P/N 280.388, is positioned on the center of P/N 280.350 tube and on the top inboard corner of P/N 280.351 and 351-1 tubes.  Note the "fishmouth" shape of P/N 280.350 where it meets the square tubing.  This is important for weld strength.  Weld all edges of P/N 280.350.  Refer to assembly dwg.  280.003 detail on the lower right section of the sheet.

 

An Aft Retaining Pin and Bracket are required on each side to lock down the aft Canopy section when in the closed position. This prevents bulging in flight and also helps support the aft Canopy section.  It consists of two Angles (P/N 280.387) fabricated from 1"x7/8"x1/8" 6061-T6 aluminum angle, and two Pins (P/N 280.386) fabricated from 3/16" steel rod.  The Angles are riveted to the Fuselage Top Stringers using three AN-4 rivets.  Shape the Pins per the sketch and weld them to each side of the Canopy Framework.  Position the Pins for maximum engagement in the Angles.

 

FITTING THE PLEXIGLASS CANOPY

 

1.        The Canopy Aft Sliding Mechanism should be constructed and in place BEFORE fitting the Canopy.  The length of the Center aft Support is determined by the actual dimension of the Canopy. This fit is by trial and error as this measurement is adjusted depending on how tightly you fit the Canopy to the Fuselage.  The cuts made in the aft end of the Canopy will directly effect this dimension.  Work for a clearance of 1/8" between the Canopy and Fuselage at the aft end.  This will eliminate the need for an aft metal fairing, as a rubber windshield type molding will suffice. Don't be tempted to lower the Canopy too much as your forward view during taxiing will suffer.  DO NOT cut the Canopy/Windshield joint until fitting is complete.

 

The height of the Roll Bar, P/N 240.364, determines the overall height of the Canopy.  The dimensions given on dwg.  240.016 will accommodate persons 6' 2" tall.  You may want to adjust this dimension.  Trimming the bottom edge of the Canopy at the aft end will also reduce the overall height, however, this may result in a shorter Canopy requiring a telescoping type rear sliding mechanism and a less streamlined windshield.  If lowered too much the Roll Bar could interfere with visibility.

 

As the final shape of the framework is determined by the Canopy shape it is desirable to contour the Canopy and Roll Bar at this time.  Your will find that the Canopy is quite flexible, allowing for some variation in the shape of the steel framework.

 

2.        Trim the fore and aft ends of the Canopy to the basic Fuselage contour.  Trim the bottom edges so the Canopy will terminate above the sliding frame.  See assembly dwg. 280.002.

 

3.        The Canopy will be attached using lower fairing strips. Fabricate the fairing strips from .032" aluminum and temporarily attach them to the Framework with Cleco fasteners.  The width of the strips is determined by the gap between the Framework, with some overlap onto the edge of the Canopy plus some overlap onto the Fuselage.  These fairing strips must not rub against the Fuselage.

 

4.        Clamp the Sliding Framework and fairing strips in place and put the Canopy in position to determine the fit over the entire surface of the Roll Bar.  Shime, between the Roll Bar and Canopy, may be required to achieve a good fit.  NOTE:  It is necessary to use blocking between the Canopy Frame and Fuselage Stringers to provide space for the future attachment of the roller mechanism.

 

5.        The Canopy is attached to the Roll Bar using AN 509-632-8 machine screws.  This requires drilling the Canopy and the Roll Bar with a No. 36 drill.  AT THIS TIME, drill only two or three 3/32" holes on the top and fasten the Canopy to the Roll Bar with 3/32 Cleco fasteners.  Some shifting will occur during the following steps.

 

6.        Check the fit of the Canopy from Fuselage Sta. 99.35 to Sta. 114.  If the framework has the proper contour, the plexiglass should lay evenly against the steel tube in this area.  NOTE: The steel tube in this area is twisted so that the flat surface of the tube will remain flat against the plexiglass.  Bend the steel framework as necessary to achieve a good fit.

 

7.        Lay out a rivet pattern along the upper edge of the fairing strips, using 2" to 3" spacing.  Drill only four or five 3/32" holes through the fairing strip and plexiglass and fasten the fairing to the Canopy with Cleco fasteners.

 

8.        It is now necessary to work from the inside of the aircraft. This requires a helper, as the Canopy is first removed to allow the helper to get in, and then, re-assembled with the helper inside.

 

9.        The person inside makes a template for the Forward Canopy Frame Member (P/N 280.352).  The Canopy contour in this area is determined by the shape of the Roll Bar, so the Forward Frame Member must maintain this Canopy contour.  NOTE:  See step 24.

 

10.      Using the template, the Forward Frame Member (P/N 280.352) is formed from steel tubing.  The forming can be done cold.  The forming jig is simply two wooden blocks nailed to your bench top. A tubing bender can be rented if you desire, and will make it easier to control the bending.  Leave the tubing long to provide a grip for bending.  If you are using block method, insert the tubing and apply pressure gradually to bend the tube to the desired shape.

 

11.      Once properly shaped, securely clamp the tube to the Canopy Sliding Framework.  Use temporary gussets, or braces, to hold the tube in place.

 

12.           Remove the Sliding Framework assembly, with tube, from the Fuselage.  Prepare the tubing for welding by adding jigging and supports to prevent distortion from the heat of welding.

 

13.      After welding the Forward Frame Member, fabricate a Canopy Locking Mechanism and fit it to the Frame Member.  Use care to align the Locking Mechanism Bracket so that the Locking Pin will align with the hole in the Roll Bar.  NOTE:  This is an angular dimension and must be determined at the time of installation.

 

14.      Re-assemble the Canopy and Framework on the aircraft.

 

15.      Drill the remaining rivet holes through the fairing strip, aft Framework, Forward Frame Member, and the Canopy.  Cleco the Canopy in place.

 

16.      Using a No. 36 drill, drill the remaining holes through the Canopy and Roll Bar.  Use 3" hole spacing.  The Canopy will be removed and the Roll Bar tapped for the 6-32 screws.  The holes in the plexiglass should be enlarged at least one size and counter-sunk to accept the heads of the screws.  NOTE:  An external strip is not required at this location if care is used in drilling and counter sinking the holes.

 

17.           Remove the Canopy and deburr all holes in the Framework and Canopy.  Tap the 6-32 threads into the Roll Bar.  The holes in the plexiglass should be chamfered, both inside and out, to prevent stress cracking.

 

18.      Re-assemble the Canopy and Framework on the aircraft. Re-check the alignment of the Canopy on the Frame and at the Roll Bar.  The next operation is to cut the Windshield from the aft Canopy.

 

19.      Use one of the methods described in the opening paragraphs of this section to cut the Canopy.  Proceed with CAUTION, you only get one chance to do a good job.

 

20.      Mark a cutting line on the plexiglass midway between the Roll Bar and the Frame Member.  A strip of masking tape on the Canopy can be used as the cutting line.  Sight this line from a distance to verify that it is symetrical on both sides of the Canopy.

 

21.      If you use the cutting wheel method, you will notice that the wheel will track only in a straight line if you cut too deeply.  Since you will be cutting on a curved surface, it may try to track away from the line.  DO NOT try to cut through the Canopy to maintain control of the wheel.  Arrange firm supports for standing on both sides of the aircraft.

 

22.      Start cutting at the top center of the Canopy.  Work down each side and cut about half way through he plexiglass.  Cut less deeply in the highly curved areas.

 

23.      After the Canopy has been cut, the edges must be filed, sanded, and polished smooth.  This is important to prevent any cracking from stress or vibration.

 

24.           Although not required, it is advisable to install a .025" strip between the plexiglass and Forward Frame Member.  The purpose is to provide a more secure surface for the sealing compound between the aft Canopy section and the Windshield.  This fairing strip should extend about 1/4" forward of the plexiglass edge.  Be sure that this strip clears the Windshield edge when the Canopy is closed.  A sealing material which has been found satisfactory is the hollow rubber weather stripping available at hardware stores.  Another type is the "silastic" synthetic rubber compound used for caulking bathtubs.  This material hardens to a firm, yet pliable surface.

 

25.      Apply the material as follows.  Open the Canopy only about 1/16" and force the material to fill this gap.  Smooth the outer surface before the material cures.  When cured, the material will have adhered to both surfaces.  Use a razor blade to cut through the material.  The cut should be made against the edge of the Windshield, so that all of the sealand is on the aft Canopy side. The material will now provide a cushion for a tight Canopy fit.

 

26.      The Canopy assembly is now ready for riveting together. NOTE:  Although the drawings specify 1/8" diameter rivets, it has been determined that 3/32" rivets are adequate for attaching the aft Canopy section to the fairings and Framework.  The 3/32" rivets are better because they exert less riveting pressure on the plexiglass.  The .032" side fairing strips can be counter sunk to accept the rivet heads and produce a smoother surface. These rivets can be "pop", Cherrymax, or AN type rivets.

 

27.      Re-assemble the Canopy on the Fuselage and Cleco in place.

 

28.           Method for installing rivets in the Aft Canopy Section.  To permit bucking the AN rivets the following procedure is utilized. After drilling the 3/32" rivet holes through the fairing strip, plexiglass, and outer wall of the Framework tubing, the assembly is taken apart.  Drill from the outer hole through the inner wall of the tubing.  Next, enlarge the hole in the inner wall to accept a 1/4" bucking bar fashioned from a drift punch.  The punch is welded to a two pound iron bar for weight.  With this "bucking bar" the backside of the rivets can be reached through the hole in the inner wall.  After the assembly is completed, these holes will be covered by an inner fairing.

 

29.           Fabricate a triangular fairing per drawing 240.027.  It is installed at Fuselage Sta. 114 Bulkhead and the Top Fuselage Stringer.  Slight compound forming will be required to match the fairing to the Canopy side fairing piece.  This is done by shrinking the upper flange of the fairing using fluting pliers. The drawings of the fairing are only approximate so the fairing must be made to fit your particular aircraft.  NOTE:  The aft Canopy side fairing may require adjustment to avoid interference in this area when the Canopy is opened.  The Fuselage Fairing is attached using AN 426AD3 rivets.

 

30.      A fairing is required at the junction of the Windshield and the top of the Fuselage.  It should be formed from soft, or half hard, aluminum (2024-T3 is useable, but, difficult to form).  To simplify fabrication, this fairing may be made in two pieces. Make a paper template to determine the actual fairing shape.

 

31.      Cut the fairing strip from the metal using the paper pattern.  Bend the angle into the piece using a mallet with the strip over the edge of a wooden block.  The curve must be formed by hand.

 

32.      With the initial angle formed, the curves are achieved by stretching the Fuselage side of the fairing.  This is done by placing the strip on a steel backup block such as a bucking bar, or large vice and striking the edge of the area to be stretched with a metal hammer.  This method eliminates the need to shrink the other side of the fairing strip, which is difficult without special shrinking tools.

 

33.      Attach the Windshield and the finished fairing per drawing 280.003.  Use a sealant between the fairing strip and Windshield. See drawing 280.003.  Rivet the fairing strip to the Fuselage using AN 426-AD3 rivets on 4" spacing.  Attach the Windshield to the fairing strip using machine screws or, blind rivets, on 6" spacing.

 

This completes the fitting of the Canopy.

 

COWLING ATTACHMENT

 

The Mustang II Cowling consists of three pieces:  a Top Section, fabricated from aluminum, and two fiberglass Side Sections.  The Cowling is a cantilever design, which is self supporting, and is

attached only at the Firewall.

 

Because the edge of the Cowling is approximately 3/32" thick at the Firewall, it is necessary to use a joggled attachment strip to obtain a flush fit.  The sketches below show two methods of obtaining this fit.  When using the joggled strip method, the Fuselage Side Skins must be extended 1/4" beyond the edge of the Firewall flange.

 

1.        Do NOT join the fiberglass halves until the Cowling has been completely fitted to the aircraft.  Use Duct Tape to hold the halves together.

 

2.        Install the Spinner backing plate on the propeller, or extension, and position the front portion of the Cowling halves to align with the backing plate.  Maintain a 1/4" clearance gap between the Cowling and the backing plate.

 

3.        At the aft end, position the Cowling halves at the Firewall by overlapping them onto the Fuselage.

 

4.           Carefully mark a cutting line around the halves so that the edges will butt against the Fuselage Skins.  The fit should be tight, or somewhat lone, as the edges will be sanded to achieve the final fit.  Like the Canopy, you only get one chance for a good fit.

 

5.        It may be necessary to re-work the radius of the Cowling, at the lower corners, to obtain a good fit completely around the Firewall.  This can be done by heating the fiberglass with a heat gun, or heat lamp, and working the shape toward the top.  The Top Section can be adjusted to take-up this excess.

 

6.        When you are satisfied with the fit of the Cowling at the spinner and Firewall, the two halves may be fastened together.

 

7.        Drill through each of the metal hole reinforcements using a No. 30 drill.  The Cowling sections are joined using Tinnerman "U" nuts, #A1784-62-1 and #6 x 5/8" flat head sheet metal screws. The Tinnerman nuts are held in place by attaching them to a 1/2" wide strip of .025 aluminum that has been riveted to the inside of the fiberglass.  Rivet the strip to the fiberglass with AN 426 -AD4 rivets using 10" spacing.

 

NOTE:  If for some reason it is necessary to relocate one of the metal reinforcements follow this procedure:  Fit a Tinnerman countersunk washer, No. A3236-012-24A, in the desired location by counterboring a hold using a 5/8" diameter rotary file in your electric drill motor.  Epoxy the washer in place.  It is possible to keep the surface as smooth as the Cowling by placing a piece of wax paper over the epoxy while it is curing.  Maintain a 3" spacing when relocating the washers.

 

8.        Once the Cowling halves have been joined, the attachments to the Firewall may be fabricated.

 

NOTE:  The following three steps (9,10, and 11) apply only to cowlings purchased from suppliers other than Mustang Aeronautics.

 

9.        There are two different methods of attachment depending on where the fasteners are to be located.  The first method is to fasten the Cowling to the Firewall with screws that go through the Firewall flange, or second, fasten it with screws that go through the fiberglass Cowling.  The method you choose will determine where the Attachment Strip is located.  Refer to the above sketches.  NOTE:  It is not necessary for the Strip to be made in one continuous piece, nor is it necessary for it to go completely around the Firewall.  Its purpose is only to support the Cowling and this can be accomplished with a number of small strips attached around the edges, however, it should be a strong attachment.

 

10.      An Attachment Strip is fabricated to fit inside either, the edge of the Cowling, or, the flange of the Firewall. #1.  The Strip is attached to the Cowling using AN426AD4 rivets, on a 10" spacing, and epoxy glue.  The epoxy is used to spread the load from the rivets and provide additional support for the Strip. #2.  The Strip is attached to the Firewall during the installation of the Fuselage Side Skins.  NOTE:  in either case, keep in mind that the Cowling is removed to perform regular service and should not be too difficult of a job.

 

11.      The Cowling is attached using Tinnerman "U" nuts, No. a1784-6Z-1, and #6 x 5/8" long flat head sheet metal screws.  You may also use Dzus Fasteners, or, 1/4 turn latches.  NOTE:  If the fasteners pass through the fiberglass Cowling, you MUST NOT countersink the holes in the fiberglass.  This would remove too much material and leave it too weak to support the Cowling.  The Attachment Strip rivets may be countersunk ONLY if epoxy is used over the entire surface of the Strip.

 

12.      The Top Section of the Cowling is fabricated from .032" aluminum.  This section is fitted AFTER the halves have been joined and the Firewall attachment completed.  The edges of the aluminum should have a slight 3/16" break to provide a tighter fit and better appearance.

 

13.           Fabricate two 1/2"x1/2" angles from .025 aluminum and rivet them lengthwise, as stiffeners, to the Top Section aluminum.

 

14.           Fabricate an inspection door and latch, for checking the oil, in the appropriate area of the Cowling.  NOTE:  The door hinge must be positioned so that, if it is left open, the wind will push it closed.  Do NOT face the hinge so that the door can be blown open during flight.

 

15.      An adjustable Cowl Flap may be fitted to the bottom edge of the Cowling if required to maintain engine temperature.  A suitable cockpit control will also be required.  It is not advisable to have a fixed Cowl Flap.  Check your engine manufacturers specifications for correct operating temperatures.

 

16.      The engine cooling baffles are bolted to the engine and are completely independent of the Cowling structure.  Use flexible asbestos strips to seal the gap between the baffles and Cowling. See photos for additional details.

 

17.      The carburetor air intake area is baffled to direct ALL air entering here toward the carburetor.  Surplus air in the Cowling can have a detrimental effect on engine cooling.  Further, this intake air can be used to increase manifold pressure which increases engine performance.  Some builders fabricate elaborate air intakes to maximize this free increase in power.  An air filter MUST be incorporated into the design of your air intake.

 

 18.     One final note.  Make certain that no portion of the Cowling touches any point on the engine, other than the carburetor which should have a flexible connection, because the constant vibration may shatter the Cowling.

 

This completes the Cowling attachment.

 

WING

 

WING JIG

 

A Wing Jig is used to support the wing spars during the construction of the Wings and the Center Section,  It should be sturdy and anchored to both the floor and ceiling of your workshop.  This discussion is for the Wing Panel construction. The Center Section Jig is similar except that it uses two Root Ribs instead of a Root and a Tip Rib.

 

Material Requirements:  (2) 4"x4"x8' wooden posts, and (1) each of 2"x2"x24", 2"x2"x6", and 2"x2"x3" steel angle.

 

1.        Fasten the 2x2x24 steel angle to the edge of one of the 4x4 members so that the lower end of the angle is approximately 32" above the floor.

 

2.        Mount the 4x4 uprights vertically with their centers 101-1/2" apart.  The vertical center line of the Root upright must be aligned with the center line of the steel angle on the Tip upright.  These uprights must be plumb.  Make the installation of the uprights as rigid as possible.

 

3.        Fasten the 2x2x6 steel angle for the Main Spar to the Jig Root upright in a horizontal position with the leg of the angle 48" above the floor.

 

4.        Fasten the 2x2x3 steel angle for the Rear Spar to the Jig Root upright in a horizontal position 25.156" below the Main Spar steel angle.  The dimension of 25.156" is a conservative estimate to prevent interference when attaching the Wing to the Center Section.  The actual face dimension is 25.160".  The .004" will be taken up when the bolts are tightened.  It is important to verify this dimension on the Center Section to prevent binding or a loose fit.

 

5.        Clamp a Sta. 141.25 Wing Rib to the Main Spar.

 

6.        Clamp the Main Spar assembly to the top side of the upper steel angle on the Jig Root upright.

 

7.        Level the Main Spar spanwise and fasten the Tip Rib to the steel angle on the Jig Tip upright.  Use the Rib forming jig holes to bolt the Rib to the angle.  Use spacers to hold the Rib away from the angle.  The Rib is centered vertically by using a plumb bob and aligning the forming jig holes.  Make sure that the Main Spar is level in both directions (ie. no twist).

 

8.           Support the Rear Spar root on the lower angle of the Jig Root upright, then lift the other end of the Rear Spar up and fasten it to the Tip Rib.

 

9.        The Rear Spar is aligned on the Root upright angle by positioning the junction of its WRL and Sta. 47.250 directly below the same junction on the Main Spar.  Use a plumb bob to set the alignment and clamp the Rear Spar to the angle.

 

One builders suggestion is to use Jack Posts in place of the 4"x4" posts.  These are the screw type that are used to raise sagging floors.  The tension can be set to just snug them up during alignment and then they can be tightened up to achieve a very rigid structure.  If the vibration loosened them, a half turn on the screw and they are tight again.  This doesn't change the alignment of the Jig because you can't lower your shop floor no matter how many turns you use.  (Don't get too aggressive as these jacks are capable of lifting the entire floor causing cracks in the walls above)

 

Attach the support fittings to the Jig using threaded rod bent in a "U" shape much like a muffler clamp.  These are snugged up during alignment just like the posts.  Having two ways to adjust the alignment of the Jig and the supports makes squaring this setup easier.  If you are concerned about the supports moving from vibration the rod can be tack welded to the posts for a permanent installation.  The whole Jig only costs about $30.00. Considering that it will be used to assemble three wing sections (MII) and will be in use for a number of months, it's worth the investment.

 

This complete the wing jig.

 

WING CONSTRUCTION

 

The Wing construction is detailed on the 230. Series of drawings.

 

1.        Form the Wing Ribs of .025" 2024-T3 aluminum.  NOTE:  Make a right and a left hand set of Ribs.  The Rib forming technique is described in Appendix Note #1.  All Ribs consist of a nose and main section, except, the Tip and Root Ribs may be formed as a single piece.  The Spar flanges are formed on a bending brake using .040" 2024-T3 aluminum.  The Spar lightening Holes are NOT flanged.  The Rib Lightening Holes are flanged 30 degrees.

 

2.        The Rear Spar flanges do not have a uniform bend due to the washout built into the Wing.  The finished bend angles are:     Top Flange - 100 degrees at Root, 97 degrees at Tip   Bottom Flange -  93 degrees at Root, 94 degrees at Tip

 

NOTE:  If the flanges are formed on a leaf type bending brake, form the Top Flange to 100 degrees and the Bottom Flange to 94 degrees.  The flanges can be re-worked to the exact angle during assembly.

 

3.           Assemble the Main Spar Cap Strips (P/N 230.303 thru 230.310) to the Spar Webb.  The Attachment Bolt holes should be drilled to 17/32" at this time.  NOTE:  The Attachment Bolts are NOT located on the center line of the Cap Strips.  It is very important to position the Attachment Bolt holes accurately.  The 17/32" Bolt holes can be reamed to the proper size of the actual NAS 149 Bolt during final assembly.  CAUTION:  NAS bolts are undersize.  A specially ground reamer or, an adjustable reamer, is required to maintain a proper fit for the Bolt.

 

4.        Rivet the Cap Strips to the Spar Webb using AN 470AD4 rivets. NOTE:  Cap Strip, P/N 230.310, must be chamfered to clear the Spar Webb radius.

 

5.        When attaching the Spar Butt Reinforcing Angles with their Spacers, the long rivets may make the riveting operation difficult.  These rivets may be replaced with AN3 Bolts.

 

6.           Assemble the Rear Spar by attaching Doubler (P/N 230.316) and wing Attach Fitting (P/N 230.317) to the forward side of the Spar Webb, per drawing 230.003.  Attach the Aileron cutout Doubler (P/N 230.321) to the aft side of the Spar Webb.

 

7.        Install the Rib Attachment Clips (P/N 230.323) at the Rear Spar ends.

 

8.           Position the Wing Spars, and only the Main Root and Tip Ribs on the Wing Jig.  See Appendix Note #6-1 and the Wing Jig Construction section for details.  The Root and Tip Rib Flanges face OUTWARD.  The 2- 1/2 degree Wing washout is established when the Ribs are aligned vertically using the rib forming jig holes and a plumb bob.  Verify that the Wing Attach points on the Main and Rear Spars will mate properly with the Center Section Fittings.

 

9.        Cut the Rib Spacers from .125" x 1/2" wide aluminum strip and fit them between the Spar Cap Strips.  These Spacers are used to build-up the Spar thickness to provide a uniform surface

for Rib attachment.

 

10.      Attach the remaining Nose and Main Ribs to the Spars with the Rib Flanges facing towards the Wing Root.  Use AN 470 AD4 rivets.  The reference marks on the Spars (station location) are the location of the Rib Webb, the flanges are inboard of the reference marks.  NOTE:  To prevent the Main Spar from sagging a support must be installed from the floor to the center of the Rear Spar at this time.  Verify that the Main Spar is straight.

 

11.      The Ribs are aligned flush with the Spar Webbs and even with the other Ribs.  Use a straight edge, or sight down the Ribs to insure that the Ribs make a "true" surface.

 

12.           Locating the Leading Edge Skin rivets.  The following describes a method that will simplify the task of finding the location of the rivet holes in the leading edge skins.  Use the Root Jig Member as a reference.  Measure along the Main Spar and record the distances from the Jig member to the center line of the flange for each Nose Rib.  Then measure and record the position of the most forward rivet on each Rib flange by measuring up from the edge of the Skin.  Draw a center line on the flange of each Nose Rib.  Do NOT use a pencil unless the Ribs are well coated with primer.

 

13.      Form the Leading Edge Skin as described in Appendix Note #5. Clamp the Skin to the Wing Structure.  Using the dimensions recorded in the previous step, measure the distances from the Jig member, and upward from the aft edge, to find the most forward rivet location on each Nose Rib.

 

14.      At this time drill the rivet hole only through the Skin, not through the Rib flange.  Reach under the Skin and position the Rib center line under the rivet hole, then drill through the Rib flange.  Cleco the Rib in place and proceed with the next Nose Rib until all forward rivet holes are completed.

 

15.      Using 2" rivet spacing, drill the remaining rivet holes in each Nose Rib, starting at the leading edge and working toward the Spar.  Use 1" rivet spacing on the Spar Flange.  Work across and down the Nose Ribs to prevent waviness in the Skin.  Fasten with Cleco fasteners as drilling proceeds.  NOTE:  The minimum distance from the rear edge of the Spar Flange to the center line of rivets on the rear edge of the Leading Edge Skin is 13/16".

 

16.      Trim the rear edge of the Leading Edge Skin so that it ends 9/16" in front of the rear edge of the Spar Flange.  This edge must be straight as the Main Wing Skin will butt up to it. Slightly break the edge of the Skin downward to insure a tight fit to the Spar Flange.  NOTE:  Be certain there is adequate rivet edge distance before trimming Skin.

 

NOTE:  Due to variations in workmanship the finished height of all of the Ribs may not provide a uniform surface for attaching the Skin.  This will result in a "dished in" surface during riveting.  This condition is usually noticed after drilling the rivet holes and with the Skin held in place with the Cleco fasteners.  Use a light held at one end of the surface and sight from the other end to detect the low spots.  To remedy this, it is necessary to use shims in the low spots.  The shims may be of .020", or thicker, aluminum, and may be for just one rivet, or extend over several rivets.  If the low spots are not found until after riveting, they may be "raised" by tapping the rivet with a mallet from the underside of the Skin.  This is less desirable because it may result in high spots but, it can be done.

 

17.      Rivet the Leading Edge Skin to the Nose Ribs in the same sequence as used above, using AN 426 AD4-4 rivets.  Start with the top surface of the Skin, then rivet the bottom, again using the same sequence as above.

 

18.      Cut the Wing Tip Doubler from .025" aluminum and form to the shape of the Tip Rib.  The Tip Doubler fits inside of the Rib Flange and is attached at the time of riveting the Wing Skins. The Doubler is used to attach the fiberglas Wing Tip Fairings. See Appendix Note #6 for details.

 

19.      If not previously installed, the Aileron Bellcranks, Marker light wiring, and plumbing for the Pitot Static Tube, etc. should now be completed.  Be certain to use rubber grommets where wires, or lines, pass through the Ribs.  Once the Skins are in place these lines would be difficult to run.

 

20.      Fit the Top Main Skin (P/N 230.333) and slightly break the edge that butts to the Leading Edge Skin.  Drill all rivet holes. NOTE:  The location of the rivet holes may be determined as described for the Leading Edge Skin, however, as both sides of the structure are accessible there is a quicker method.  With the Skins removed lay out and drill all of the rivet holes in the Wing Ribs using a 3/32" or #40 drill bit.  Next, clamp the Skin in position and using a #40 "aircraft" drill bit of at least 6" length back-drill the Skin from the inside.  Now, from the outside, re-drill the holes with a #30 size drill.  Complete drilling and dimpling both Skins before riveting.

 

21.      Attach the Aileron Hinge Reinforcement (P/N 230.329) and the Piano Hinge to the Main Skin trailing edge.  Make certain that the hinge on the wing will match the hinge on the Aileron. Adjust the position of the Reinforcement on the Rear Spar to obtain the correct skin contour.  Drill the rivet holes.

 

22.      The Bottom Main Skin may now be fitted, but, NOT riveted.

 

23.      The Wing Skin Stiffeners (P/N 230.331) may be fitted after the Top and Bottom Skins are fitted, or postponed until after fitting the Wing Trailing Edge Extrusion.  It is desirable to align the rivet holes for the Stiffeners with the holes drilled for attaching the Skin to the Ribs.

 

24.      Fit the Trailing Edge Extrusion following the Wing Trailing Edge alignment procedure described in the Aileron Construction section.  It is necessary to have the Aileron in position to properly align the trailing edge.

 

25.      After all components are fitted and drilled, disassemble, deburr, dimple and rivet.  Rivet Top Skin first then, rivet the Aileron Hinge and Reinforcement.

 

26.      Lower Wing Skin Attachment:  The Lower Main Wing Skin is the last to be attached.  This skin is somewhat more difficult to attach due to the limited access for bucking the back side of the rivets.  The following method will enable you to attach the Skin without the use of blind rivets.

 

Securely position the Skin on the Main Spar using Cleco fasteners.  Reaching up from the trailing edge with the bucking bar, install all rivets in the Main Spar outboard of Rib Sta. 119.25.  Next, install the rivets in the Tip Rib and Rib Sta. 130.25, working down from the Main Spar.  On Rib Sta.  130.25 there will be two or three rivets at the trailing edge that you cannot reach.  These will be installed later.  Next, install the rivets in the Rear Spar outboard of Rib Sta. 130.25.  Now remove the Cleco fasteners so that the inboard section of the Wing Skin can be flexed outward for access to the remaining rivets in Rib Sta. 130.25.

 

To reach the remaining rivets, it is necessary to reach between the loose inboard portion of the Wing Skin and the structure. The Skin must be supported in some manner to prevent sagging and creasing of the Skin.  This can be done by using a string tied to the inboard upper corner of the Skin and attached to the ceiling.

 

Install the rivets in Rib Sta. 119.25, working down from the Main Spar.  To complete the Skin attachment, install the rivets in the Main Spar inward to the next Rib and down the Rib to the Rear Spar.  Repeat this procedure for each rib bay inward to complete the Wing.  The rivets in the Rear Spar may be installed as riveting progresses.

 

The Easy Method for Wing Skin Attachment:  This method uses some blind rivets and proceeds as follows.  Install all of the rivets in the Main Spar.  To obtain a "fair" surface and offset the possibility of the Skin stretching during riveting, it is best to install one rivet every 18" along the Spar.  Next install a rivet midway between each of these rivets.  This will prevent the metal from "creeping".  Install all of the remaining rivets.

 

Install rivets in all of the Ribs, working down evenly from the Main Spar.  The last rivet in each Rib, just forward of the Rear Spar, will not be accessible to the bucking bar.  This rivet must be a blind type rivet.  Next, rivet the Skin to the Rear Spar, and complete the riveting required on the inboard portion of the Skin, aft of the Rear Spar.

 

NOTE:  Make some provision for removing the Aileron Hinge Pin as it will be necessary to remove the Ailerons for service.  Also fabricate an access opening beneath the Aileron Bellcranks to permit service and inspection.  This completes the Wing assembly.

 

This complete the wing construction

 

AILERON CONSTRUCTION

 

The construction of the Ailerons is similar to that of the Elevators and Flap.  The Aileron consists of the formed Skin and Skin Stiffening Angles of .016" 2024-T3 aluminum, and End Ribs of .025" aluminum.  The counter-weight assembly and Actuating Rod are of steel and lead.  All weight aft of the hinge line must be balanced by a weight forward of the hinge line.  To keep this weight to a minimum the Skins are made of .016" aluminum.  NOTE: AN 470-AD4 universal head rivets MUST be used for attaching the Control Rod Bracket and the Counter-weight assembly.

 

1.        Form the Aileron Skins (P/N 230.501 and -1) per drawings 230.007 & 008. NOTE:  See Appendix Note #10.

 

2.        Form the Aileron Spars (P/N 230.502 and -1) per drawing 230.008.

 

3.        Attach the Aileron Skins, the Skin Stiffening Angles, Hinge, and End Ribs, to the Aileron Spar.  Rivet ONLY the top side of the Aileron to facilitate alignment of the trailing edge.  DO NOT drill rivet holes in the Spar lower flange at this time.

 

4.           Because the Wing has a 2-1/2 degree Washout, the Wing and Aileron must be constructed with this amount of twist built-in. This must be done as one operation to deep the trailing edge straight.  The following method is a simple way to obtain the desired alignment.

 

Construct a pair of Airfoil Profile Boards, paying particular attention to the center line of the shape, by cutting the Wing Root and Tip airfoil shapes from 1/4" plywood.  Mount the Aileron in position on the Wing and slip the Profile Boards in place at the Root and Tip.  This will properly position the Wing Root and Aileron Tip.  Clamp a suitable straight board just forward of the trailing edges.  The Wing Trailing Edge Extrusion will be riveted with this board in place, so clamp the board in place at least 1" ahead of the trailing edge.  With the trailing edge held in place, the Wing Trailing Edge Extrusion can be drilled and riveted.  The bottom skin of the Aileron is also drilled and riveted to the Aileron Spar.  Refer to photo #11 for details.  Be certain to coordinate the station location of the Wing Root trailing edge with the Flap trailing edge.  Aileron Balance:  The Aileron Counter-weight is made by filling the tube with lead until the desired balance is achieved.  The Ailerons must balance 100%.  To check the balance, the Aileron is mounted in a level attitude on a set of knife edges, or bearing blocks, so that it is free to rotate about the mounting Hinge Pin.  The Ailerons must be balanced after they have been painted. Keep the lead sufficiently hot while pouring to avoid air pockets in the lead.  Cut an opening in the Wing lower Tip Skin to provide free operation of the Counter Weight.  Provide a means of removing the Aileron Hinge Pin to facilitate servicing the Aileron.  In operation, the counter-weight extends below the wing surface when the Aileron is in the "up" position.  When the Aileron is in the "down" position the counter-weight remains inside of the Wing Tip.

 

In the interest of economy, some Mustang builders are purchasing, or fabricating, Landing Gear Legs that are NOT satisfactory.  The following is the recommended procedure for fabricating the Gear legs.

 

There are several alloys suitable for use, such as SAE-E4340, E6150, or, E5160.  These are high carbon alloys all capable of heat treating to the high tensile strength required.  Start with either bar, or plate, stock 5/8" thick for the Mustang II (1/2"for the Midget Mustang) and cut the material to shape.  If the material is mechanically sheared, it must be cut 1/2" oversize, and if it is flame cut, it must be cut 3/4" oversize and pre-heated before cutting.  The material is then milled down to the correct dimensions and the edges shaped with a large radius.  This is necessary to remove the edge area that will have minutecracks as a result of the shearing or cutting operation. Most milling operations will leave a rough edge, so the edges must be sanded smooth by hand.

 

The next operation is to grind both surfaces down to the dimensions specified in the drawings.  The grinding removes any of the surface that may contain defects from the steel rolling process and the de-carbonized surface layer that will not accept heat treating.  Next, drill the upper end attachment holes and the axle attachment holes.  These holes are then reamed and chamfered.

 

The next step is to bend the Gear Legs to shape.  NOTE:  The bend radius and the biased plane of bending are shown in the drawings. In order to bend the Legs to shape, it will be necessary to heat the metal.  The temperature must NOT EXCEED 1400' f, nor should it be any LESS than 1200' F.

 

The Gear Legs are now sent to be normalized and heat treated, preferably by an FAA approved company that can provide certification of the process used and the hardness achieved.  The heat treating is to be in accordance with Mil.  Spec.  H-6875F. The Rockwell number for hardness is specified in the drawings. Once the heat treating is complete, the Legs are sent to a facility for a COMPLETE magnetic particle inspection (Magnaflux).

 

This is a complicated process and Legs are rejected quite often. Defects are generally caused by improper processing on the part o the heat treating company, if procedures are not closely followed.  Impurities in the metal are also a significant cause of defects.  These problems can be avoided by using an electric furnace for heat treating and using quality steel as indicated by the letter "E" in the metal designation.

 

Landing Gear Legs, which meet the above specifications, can be purchased from Mustang Aircraft.

 

TOOL REQUIREMENT FOR ALUMINUM AIRPLANE CONSTRUCTION

 

Air Compressor - 1/3 hp minimum, larger size desirable

Rivet Gun - 3x size most useful for all purposes.  Should include

            an air regulator.

Rivet Sets for gun - for AN470-AD3, -AD4, and AD5 rivet heads

                           Mushroom set for flush head rivets

Bucking Bars - 2.5 to 3 lb. weight with different head shapes

Rivet Squeezer - with assorted sets and dimpling dies

Bending Brake - 18" is adequate if kits are purchased from Mustang

Accurate Rule - 12" and 48"

Tape Measure - 10 ft.

Countersink Tool - adjustable stop type with 100 degree cutters with 1/8" and 3/32" pilots

Cleco Fasteners - 100 each of 1/8" and 3/32"

Cleco Pliers -

"C" Clamps - assortment of 1", 2" and larger sizes

Rivet Cutter - many rivets need to be cut to proper length

Fluting Pliers - for shrinking sheet metal

Hole Cutting Tool - Adjustable to 4" diameter

Hole Flanging Tool - for lightening holes in Ribs & Bulkheads

Hand Nibbler - Radio Shack circuit board type

Tin Snips - Duck Bill 12" for straight cutting

Aviation Snips - right and left cutting (avoid serrated cutting edges)

Metal Files - 12" Flat Mill, Round edge Smooth, 1/4" Chain Saw,1/2" Round Mill Files

File Cleaner - stiff wire brush will do Electric Hand Drill - 3/8" chuck variable speed, 1800 rpm minimum

Drill Press - with 3/8" or 1/2" check, table top size is adequate

Drill Bits - 12 ea. of #30 & #40 size, 4 of #20, 2 of #13, 3 of 1/4", 1 ea. of #D, 5/16" , and 3/8".

Right Angle Drill Adapter - for drilling in odd locations

1/4 x 28 Bits - #30 and #40 size for above Angle Drill

Large Drill Bit - 1/2" or larger for deburring drilled holes

Deburring Tool - for finishing edges of metal

Band Saw - Variable speed for cutting wood and metal.  Needs a very slow blade speed (under 300fpm) to cut steel.

Plumb Bob - Machinists Squares, Carpenters Square, Spirit Levels, Angle Protractors, for squaring structure

Respirator Mask - MUST have for spraying zinc Chromate

Hand Grinder - Dremel tool with sanding drums.

Center Punch - Must have.

Leather Gloves - or plenty of Band-Aids

Buffing Wheel - for maintaining finish on rivet sets and bars

Bench Grinder - 4" to 6" for finishing steel parts

Tubing Flaring Tool - aircraft version NOT home plumbing version

Tubing Cutter -

Torque Wrench - Must have for AN and NAS type bolts

Wire Stripper and Crimping Tool - for installing electrical Sys.

 

NOTE:  Some specialized tools may be available from your local EAA chapter members.  Others who have built metal aircraft will have most of the above, or will have already located some of the

hard to find tools.

 

APPENDIX CONSTRUCTION NOTES

 

NOTE #1:  FORMING RIBS AND BULKHEADS -

 

Forming blocks for making the Ribs and Bulkheads, are made from 5/8" thick material.  Plywood, Masonite, hardwood and chip board are satisfactory materials.  Forming block material can be kept

to a minimum by forming the larger items first, then cutting down the block for the next smaller piece.  Lay out the part pattern on the forming block material VERY accurately, using the Station layout drawings.  The accuracy of the Rib forming blocks is especially important as it can effect flight performance.  Allow for the thickness of the metal of the part to be formed when laying out the forming blocks - for example - the Fuselage Bulkheads are made of .032" aluminum so the forming blocks must be .032" smaller all around than the Station layout drawings.

 

All of the forming edges on the forming blocks should be sanded to a 1/8" radius.  You need only make one forming block for each Rib Station as a radius can be sanded on both sides of the forming block.  The 3/16" Jig Holes MUST be located accurately as they are used as a reference point throughout construction of the Wings.  NOTE:  Do NOT  glue the drawings to the forming block material as moisture will distort the paper out of shape.

 

Cutting out the Metal Blanks - To lay out a pattern on a sheet of aluminum, a Marking Jig is required.  The Marking Jig is made by drilling a 1/16" hole in the center of a 1-1/8" diameter round piece of 1/8" aluminum.  The center hole should accommodate the tip of a ball point pen.  To use the Jig, place the forming block on the sheet metal.  Put the ball point pen in the hole in the Jig and run the Jig, like a wheel, around the forming block. This will mark a suitable cutting line on the sheet metal.

 

After cutting out the blank, all edges must be filed, or sanded, smooth, to be free of nicks or cutting marks.  This is important. A nick along the edge of a piece can crack during forming.  Where two flanges meet at a corner, the flanges should end short of the corner by at least 5/32", with a radius cut into the corner to remove the material that would bunch-up and cause a crack at this point.

 

Forming Ribs and Bulkheads - Photos 1 thru 5.  The method described here is a combination of fluting (shrinks) and notching (removes) metal on the edges of the material being formed.  This approach, which is performed in three distinct steps, eliminates the need for any excessive shrinking, or stretching, of the aluminum.  By using this approach, with a generous bend radius, it is possible to form parts from the relatively hard "T3" grade aluminum.

 

Step 1.  Initial Forming Operation - Position the metal blank on the forming block by inserting bolts through the Jig Holes. Cover the blank with a back-up block made from 1/4" plywood cut slightly smaller than the forming block.  In the case of Ribs, the next smaller Rib forming block can be used.  Using a lightweight wood, plastic, or rawhide mallet, work the flange down gradually and evenly.  Go slowly around the flange several times before achieving the full bend.  Use numerous light blows, rather than heavy blows, so that the metal will not be stretched. As the flange progresses, the excess metal, due to the curvature of the part, will develop into scallops in the flange.  This waviness is of no concern at this time as it is eliminated in Step 2.  The object here is to set the radius along the bend line tightly to the forming block.

 

Step 2.  Completing the Flange Angle - Due to the "spring-back" characteristics of aluminum, and the excess material in the flange, you will only be able to achieve a bend angle of about 60 degrees during forming.  Remove the piece from the forming block and complete the bending of the flange to the required angle.  On Ribs, the required angle is 89 degrees.  This is done by laying the piece on your workbench, and tapping the flange until the required angle is achieved.  This operation will remove the waviness from the flange, but, now the piece will be bowed.  If this operation has not removed all of the waviness in the flange, it can be removed using flat nosed pliers.  Tape the plier jaws to prevent marring the metal.

 

Step 3.  Straightening the Piece - The final operation is to remove the bow that has developed in the piece.  The bow is removed by the use of "fluting pliers".  These are slip joint pliers that have been modified by attaching matching male-female dies to the jaws.  By squeezing the flange with the fluting pliers, excess metal is taken-up by the flutes formed in the metal.  The flutes must not interfere with the future spacing of rivets so, it is necessary to mark their location on the flange before fluting the edges.  The rivet spacing on the Wing Ribs is 2 inches, starting 1 inch from the front Spar Webb.  The spacing on Bulkheads is also 2 inches, except where noted otherwise.  One flute, spaced midway between rivet locations, is sufficient on all Ribs and Bulkheads where there is only slight curvature.  On the forward end of the Nose Ribs the curvature is greater and requires two flutes between each rivet.  Determine the straightness of the piece by sighting down its length, or, by using a straight edge.  Increase the depth of the flutes as required to achieve a straight piece.

 

The circumference of the lightening holes in the Wing Ribs are flanged to 30 degrees and can be formed using matching die blocks, a hole flanging tool or, flat nose pliers.  DO NOT attempt to achieve the full bend in one operation, but, work around the hole several times.

 

Forming Bulkhead Inner Flange - The steps previously described, apply to shrinking the Outer flanges on the Ribs and Bulkheads. The forming of the Inner flanges is a stretching operation and the metal must be worked SLOWLY to prevent tearing or cracking. It is very important that the edge to be stretched is smooth and free of nicks.  Fine emery paper is used to polish these edges before forming the flange.  Due to the limited stretching ability o the metal, the Inner flanges are smaller.  The mallet used to form the flange should have some curvature to its face to reduce the possibility of striking with a sharp corner.  The final straightening of the part is done by additional fluting, or stretching, as required.

 

It is also necessary to notch the Outer flange of the Fuselage Bulkheads at the areas of greatest curvature.  At the top of the Bulkheads, it is sufficient to place one notch between each rivet location.  At the bottom corners, where curvature is greatest, it i necessary to reduce the rivet spacing to 1-1/2" to accommodate more notches.  The purpose of the notches is to remove the excess metal in the flange where fluting is not enough.  Drill the point of each notch with a 3/16" drill before cutting the notch.  This will relieve the strain at this point.  The notch should be filed smooth.   (See sketch on page 12   appendix.)

 

NOTE #2:  WING FITTING ATTACHMENT PROCEDURE

 

TOOLS AND MATERIALS NEEDED

 

Two lengths of 35/64" steel dowel 1-1/2" long.  (35/64" drills will work)

Three letter "D" size high speed drill bits.

Adjustable reamer to 1/4". (may not be needed, see text)

Adjustable reamer to 9/16" or, a re-ground solid reamer ground to the diameter of YOUR attaching bolts.

AN 4-15 and -17 bolts, nuts, and washers for Fitting attachment.

Drill Press and Cutting Oil.

 

(Note:  adjustable reamers are available from Enco Manufacturing, Chicago, Ill or, local machine tool suppliers)

 

PROCEDURES

 

The four Wing Fittings containing the five pre-drilled bolt holes are to be installed on the forward side of the Spar assembly. The four Fittings without the attaching bolt holes are used on the aft side of the Spar assembly.  The Wing Fittings, P/N 220.304, as supplied by Mustang Aircraft, will have a 35/64" pilot hole drilled for the 9/16" Wing Attaching Bolts, in all fittings. The Wing Fittings have been heat treated so they will be more difficult to drill and ream.  The use of cutting oil and a lower RPM drilling speed will produce satisfactory results.

 

POSITIONING THE FORWARD FITTINGS

 

Refer to drawing 220.002 for Model M-II or, drawing 24 for Model M-I for the dimensions and details.

 

Clamp one of the pre-drilled Fittings to the lower location on the forward side of the Center Section Main Spar assembly (either left or right side).

 

NOTE:  The lower Fittings extend farther from the Spar than do the upper Fittings.  The next operation is to drill the five attachment bolt holes using a letter "D" size drill.

 

The use of a drill press is recommended as these holes should be drilled as accurately as possible.  As most drill press tables are quite small, compared to the Spar assembly, some form of support must be arranged to hold the opposite end of the spar.

 

First, determine that the axis of the drill is perpendicular to the drill press table.  Then, using a spirit level, block up the end of the Spar assembly so that it is square and level in relation to the table. 

 

The Spar must be level in both directions.  Clamp the Spar to the drill press table to maintain alignment.

 

DRILLING

 

Once the Spar is properly leveled, drill the first hole through the outermost bolt hole (nearest the 35/64" hole).  When drilling trough material of this thickness it is necessary to prevent the drilling chips from packing to the end of the drill bit which leads to oversize holes.

 

Use plenty of cutting oil and withdraw the drill from the hole after each 1/8" to 1/4" of depth to clear the end of drill flutes.  After completing this first hole insert a letter "D" size drill to prevent movement.

 

Move the Spar assembly to place the most inboard bolt hole in position for drilling.  Clamp in position and drill this hole in the same manner.  Place another letter "D" size drill in this hole and drill the remaining three bolt holes.

 

POSITIONING THE AFT FITTING

 

Using a felt pen, draw a center line 1" long at the small end of one of the "bland" Wing Fittings.  (This line must be removed from the Fitting prior to final attachment).

 

Position this Fitting  on the aft side of the Spar assembly.  Align it with the Fitting on the forward side by inserting a 35/64" dowel, or drill through the large hole in both Fittings.  Position the aft side Fitting so that the center line is visible through, and centered on, the most inboard bolt hole.  To accomplish this it is necessary to move the "D" size drill to the next inboard hole. Clamp the assembly and drill the hole using a letter "D" size drill.  Move the "D" drill to this hole and drill the ramaining holes.

 

NOTE:  If it is not possible to clamp the Fitting securely in place to prevent movement, or chip build-up, it is best to drill into the fitting enough to mark the location.  Then remove the Fitting and complete drilling the hole.

 

BOLT INSTALLATION

 

AN bolts will be as much as .003" undersize.  The letter "D" size drill is .004" undersize.  It should now be possible to LIGHTLY drive the bolts into place.  This snug fit is important for proper support of the Fittings.  If it is necessary to enlarge the holes, use an adjustable reamer NOT a 1/4" solid reamer which is exactly .250" and is much too large.  It may be possible to use a 1/4" PIN reamer (sometimes called a dowel reamer) which is a solid type reamer but, it is ground .002" undersize.  Mark the location of each Fitting so that they are re-assembled in the same position.

 

FINAL ASSEMBLY (lower Fitting)

 

Deburr all holes.  Remove the center line drawn on the Fittings and zinc chromate primer ALL steel parts that are not cadmium plated.  This may include the bolts that have had their plating scrapped off.  Several heavy coats of zinc chromate primer are recommended on the Fittings in contact with aluminum.  If it is possible attach the Fittings while the last coat of primer is still wet.  Bolt the Fittings in place.  Position the bolts so the nuts are on the aft side of the Spar.

 

INSTALLING UPPER SET OF FITTINGS

 

There is a section in the Construction Manual which describes a method of establishing the Wind dihedral and location of the upper set of Wing Fittings by using the completed Wing Spar as part of the process.  When this method is used, the Wing Spar attaching bolt holes (upper and lower) must be drilled to 35/64". Attach the Wing Spar to the Center Section Spar by inserting a 35/64" dowel through the lower Wing Fittings installed above. Attach a drilled Wing Fitting to the forward side of the upper location on the Wing Spar using a 35/64" dowel.  Elevate the Wing Spar to the 5 degree angle of dihedral.  This angle is 4 degrees if it is measured on the top flange of the Wing Spar.  Securely camp the upper Fitting to the Center Section Main Spar and remove the Wing Spar.  Drill the bolt holes using the Fitting as a guide.  Use the method described earlier for locating and drilling the aft side upper Fitting.  Bolt the Fittings in place.

 

ESTABLISHING DIHEDRAL

 

To set the dihedral angle as described above requires an accurate spirit level protractor.  If one is not available use the following method.  This method also requires the use of completed Wing Spars with the 35/64" holes drilled.  To set the dihedral angle with the Wing Spar attached requires a straight edge or a flat working surface approximately 16' long.  In most cases this will be your work area floor which are usually not flat.

 

Place the Center Section Spar on blocking material to raise it of the floor.  Attach a string to the blocking at the opposite end from which you are working and stretch it along the bottom edge of the Spar and extending out past the Wing tip.  The string should be fixed at the outer end so that it remains in line with the bottom surface of the Center Section Spar.  Attach the Wing Spar to the Center Section with a 35/64" dowel through the lower Fitting.  Raise the Wing Spar a distance of 9.625" measuring from the bottom surface of the lower flange to the string.  Clamp the upper Wing Fitting in position on the Center Section Spar and follow the drilling instructions above.

 

ALTERNATE WING FITTING METHOD

 

Many builders prefer to complete the Center Section and Fuselage prior to construction of the Wings.  In this case the Wing Fittings on the Center Section would already be in position. They should have been fitted as accurately as possible using the dimensions in the drawings.  If this approach was used it is now necessary to determine the fit of the Wing Spar Caps to the Wing Fittings to set the correct dihedral angle.  To do this ONLY the lower set of Wing Spar Cap Strips are riveted in place.  Attach the Wing Spar to the Center Section with a 35/64" dowel through the lower Fittings.  Trial fit the upper Cap Strips to the Wing Spar and Center Section to determine the correct location for the bolt hole.  Drill a 35/64" hole in the upper Wing Spar Cap Strips.  Attach the upper Cap Strips to the Center Section with a 35/64" dowel through the upper Fittings.  Elevate the Wing Spar to the correct dihedral angle (use either method above) and clamp the Cap Strips in position on the Wing Spar.  Remove the Wing Spar assembly from the Center Section and proceed with riveting the Cap Strips in place.  It may simplify installation if the Caps Strip rivet hole locations are pre-drilled in 3/32" diameter.  This method of matching the Wing Spar to the Center Section may be more cumbersome but, it is entirely satisfactory.

 

REAMING FOR WING ATTACH BOLTS

 

The Wing attach bolt holes should be reamed to a zero clearance, or light tap fit, of the Wing Attach Bolts.  It is necessary to ream the Wing Spar and Center Section Fittings, as an assembly, to insure obtaining a "true" hole.  To do this correctly, attach the Wing Spar to the Fittings with 35/64" dowels through both the upper and lower Fittings.  Ridgeldly support the Wing Spar so that there is NO movement.  Remove one of the dowels.  Measure YOUR Wing Bolts and using the correct size reamer (either adjustable or solid type ground to size) ream the hole for proper fit of the Bolt.  Mark the Bolt so that it is always used in the hole in which it was fitted.  It is generally best to turn the reamer by hand as power reaming with a drill motor may cause oval shaped holes.

 

Also, to provide space to turn the reamer, just the Wing Spar, not the completed Wing, should be used at this time.  DO NOT use extensions on the reamer handle and attempt to turn it from in front of the Wing as this will almost guarantee oval shaped holes due to the leverage of the extension.  With the Bolt installed in the first completed hole, remove the other dowel and ream the second hole.

 

EXPLANATION

 

Although the methods described for positioning the Wing Fittings and drilling the bolt holes appears complicated and time consuming it does eliminate the need for exacting precision and reduces the possibility of creating oversize or out of round holes. Although it is desirable to strive for the greatest accuracy there must be some allowances.  Using these methods will still produce a true hole, with 100% bearing contact on the bolt, even if the drill bit is not held perpendicular to the material. (You should have no difficulty in aligning the drill to within 1/2 degree)

 

If you pre-drill the aft side Wing Fittings to match the forward side Fittings you would need 100% accuracy in drilling through the Extrusions in order for the holes to line up.  Worse yet would be to attempt to drill through the Extrusions with pre-drilled aft side Fittings in place.  As the drill cuts through the material it would strike the edge of the pre-drilled hole and be flexed over to align with that hole.  It would appear that the holes align when actually the hole through the Extrusion is distorted which greatly reduces the bearing area on the bolt. This distorted situation is shown (exaggerated) in the accompanying sketch.

 

NOTE #3:  POSITIONING OF SKINS -

 

Use Cleco metal fasteners to support the skins while positioning, drilling, and riveting the skins in place.  Use the proper size fastener to avoid damaging the rivet holes.  Their use is more than a convenience.  They hold the skin tightly to the Ribs and Bulkheads to insure proper alignment of the holes.

 

At some locations, one skin overlaps another, making it necessary to rivet the inner skin first.  In this case, use only a few flush rivets to hold the inner skin.  When the outer skin is attached, its rivets will pass through, securing both skins.  The rivet pattern used on the inner skin should not interfere with the final pattern used on the outer skin.

 

NOTE #4:  RIVETS -

 

Use AN426 AD rivets to attach all Skins.  This is a flush head rivet with a head angle of 100 degrees.  The length will vary depending upon the thickness of the Skin and the structure being riveted.  To rivet the Skins to the Ribs and Bulkheads use 1/4" long x 1/8" dia. (AN 426 AD 4-4) rivets.  This is a flush rivet so the Skin and structure must be dimpled to accommodate the rivet head.  Skins of .032" metal may be countersunk, rather than dimpled, by using 1/4" long x 3/32" dia. (AN 426 AD 3-4) rivets and reducing the rivet spacing to 1/2 the distance indicated in the plans (2" spacing equals 1" spacing with the smaller rivet). Countersinking the .032" skins will improve the overall surface smoothness, but, it is more time consuming and must be done VERY accurately.

          

The structural rivets, used for all of the internal structure, are AN 470 (universal head).

 

The anchor, or plate nuts, (AN 366) used where you cannot reach a nut behind the structure, are held in position behind the surface using AN 426 AD 3 rivets.  This is a flush head rivet and is set into a countersunk hole.

 

NOTE #5:  FORMING THE LEADING EDGE AND TAIL SECTION SKINS

 

These Skins can be formed by hand.  The forming will be simplified if the Skins are first crimped SLIGHTLY in a bending brake.

 

Clamp a board (1"x4") to each trailing edge and slowly fold the metal over to align the trailing edges, with a board inside to act as a spacer.  Make sure that the trailing edges align and clamp them together.  Place another board on the surface of the Skin, near the leading edge, and press down until the desired radius is formed.  The closer that this board is to the leading edge, the sharper the radius.  (See sketch page 12 of appendix)

 

An alternate method, described in Sport Aviation Magazine, is to use vacuum to form the Skin.  Plastic bags are taped over the ends of the partially folded sheet and the trailing edge is taped to prevent air from entering.  A vacuum cleaner hose is then fitted to one of the bags and the air is drawn out.  This will collapse the Skin to the desired radius.  A larger board is required in between the Skins to prevent a sharp radius if the vacuum is applied to quickly.  A board on the outside leading edge will help to guide the bending.

 

NOTE #6:  ATTACHING THE FIBERGLASS TIPS -

 

A flange, or Doubler, is formed from .025" aluminum and attached to the inner surface of the Rib flange at the time of attaching the Skins.  By attaching it to the inner surface, a joggle is made to  insure a flush fit of the fiberglass parts.  The Tips are the attached to this strip.  Provide a means to remove the Tips, especially if lights, or antenna, are installed inside them.  One method is to use plate nuts and machine screws to attach the Tips.  These are more than cosmetic fittings, they contribute to the proper flow of air over the surfaces.

(See sketch page 12 of appendix)

 

NOTE #6-1: MAIN SPAR -

 

The weight of the Main Spar assembly in the Jig, during construction, will cause the Main Spar to sag.  The center of the Spar MUST be supported during the fitting of the Skins, to insure that the Spar is straight.

 

 

NOTE #7:  DIMPLING PROCEDURE -

 

Because all Skins are attached using AN426 AD-4 flush head rivets, it is necessary to "dimple" the Skin and supporting structure around the rivet hole to accept the rivet head.  A dimpling die for this operation can be made from a steel bar 3/8" thick by 2" x 6".  Drill several #30 holes into the bar at various locations is to permit dimpling in corners, etc. Countersink these holes using a 100 degree cutter.  The diameter of the countersink should be somewhat larger than the rivet head, to allow for the thickness of the metal being dimpled.

(Appendix pg. 12)

 

To dimple the metal, hold the dimpling bar on the inner side of the metal, insert an AN 426 rivet through the metal into a convenient hole in the bar.  Using the Flush Type rivet set in the  rivet gun, strike the rivet head a short blast, thus driving the rivet head and metal into the countersunk hole in the bar. The rivets used as dies in this operation will last for only about 10 operations.  Commercial Dimpling Dies, to be used in squeezers or rivet guns, are available from various suppliers.

 

NOTE #8:  INSURING TIGHTLY FITTED EDGES -

 

To obtain a tight fit on Skin seams, or where one edge of the sheet metal overlaps another, it is helpful to "break" the edge

of the metal.  A break of 5 to 10 degrees and 3/32" wide along the edge of the metal will insure that it is drawn down tightly when riveted.  The break can be set using a mallet, with the metal over a straight edge, or, using the same tool used to flange the inner edges of the holes in the Ribs.

(see sketch on page 12 of appendix)

 

NOTE #9:  LAYING OUT THE METAL BLANKS -

 

Fabricate a guide washer 1" in diameter from 1/8" aluminum stock.

Drill a center hole large enough to accommodate the tip of a ball point pen.  To use:  Place the washer against the forming block and mark the cutting line by rolling the pen around the block.

(See sketch on page 12 of appendix)

 

 

NOTE #10:  CONTROL SURFACE CONSTRUCTION -

 

Due to the sharp bends required to form the trailing edges of the control surfaces it is necessary to provide a relief hole in the edge to prevent a fatigue crack from spreading. Use a size #40 drill bit and drill a hole in the trailing edge radius about 1/2" from the end of each of the bends. Should a crack develop this hole will prevent it from progressing along the edge.  This is similar to the technique used to stop cracks in glass or plexiglas except, here it is done before the crack begins.

 

NOTE #11:  MISCELLANEOUS CONSTRUCTION INFORMATION

 

1.        Cross check ALL drawings.  Dimensions and part numbers are not included on each support drawing.  Construction details common to several components are shown on only one drawing.

 

2.           Perform construction in the following sequence.  It will be the most economical in terms of labor, material, and the jigs required.

 

                      a.  Wing Spar Assemblies (Center Section Spar first)   

                      b.  Center Section Assembly

                      c.  Forward Fuselage Section

                      d.  Aft Fuselage Section (Tailcone)

                      e.  Empennage (Fin and Stabilizer)

                      f.  Outer Wing Assembly

                      g.  Control Surfaces

                      h.           Miscellaneous Assemblies (Control Linkages,                                 etc.)

 

Wasted metal can be kept to a minimum by first cutting out the larger pieces such as Skins and Bulkheads.  The Ribs, and other smaller pieces, can be made from the stock left from cutting out the bigger items.

 

3.        The edges of all aluminum pieces should be dressed with fine emery paper to remove all nicks and tool marks.  All rivet holes must be deburred.  The corners in all cutouts should have a minimum radius of 3/32".  This is especially important where the metal is to be bent, or formed.

 

4.           Remember to cut Skins as right, or left, top, or bottom.

 

5.        Unless specified otherwise, all bend radius must be at least three times the metal thickness.  Where possible, the bend line should be across the grain of the metal.  If a part requires bends in two directions place the grain across the side bearing the greater load.  NOTE:  The bend line dimensions on the drawings are the outside, or finished,

dimensions of the part to be formed.  Allow for the thickness of the material when laying out parts.

 

6.        Drilling thick aluminum.  See "Drilling", appendix page 4.

 

7.        Bolt length is determined so that NO portion of the structure bears on the bolt threads.  A maximum of two washers is permitted.

 

8.        All steel sheet and tubing is chrome moly, 4130 alloy, in the normalized condition - 4130N.  All aluminum used is standard stock types.  The aluminum is available at all major aluminum or steel wholesale outlets such as:  Central Steel and Wire, Ryerson Steel, Alcoa Aluminum Distributors, Etc.  All hardware items are standard AN specification and are available from all aircraft supply outlets.  All material and hardware is available from Mustang Aeronautics.

 

REFERENCE MATERIALS

 

           FAA AC No. 43.13-1A "Acceptable Methods, Techniques,

           and Practices - Aircraft Inspection and Repair"

           Superintendent of Documents

           US Government Printing Office Washington, D.C. 20402 (required reading)

 

           Sheet metal construction manuals (assorted)

           Experimental Aircraft Association

           Wittman Field

           Oshkosh, WI   54903-3086

 

           "Light Aircraft Construction"

           Pazmany Aircraft Corp.

           PO Box 80051S

           San Diego, CA   92138

 

           "Sportplane Builder"

           "Firewall Forward"

           Tony Bingelis

8509 Greenflint Lane

           Austin, TX   78759

 

SOURCES OF MATERIAL

 

           All aircraft components:

             Mustang Aeronautics

             P.O. Box 1685

             Troy, MI  48099 (810) 362-4295

 

           Aluminum, Steel, Hardware, Instruments:

             B & F Aircraft Supply

             6141 W. 95th St.

             Oak Lawn, IL   60453

             (800) 345-2558

 

Fiberglass items:                           

             Rattray Aircraft Co.

             2357 Afton Rd.

             Beloit, WI  53511

             (608) 362-4611

 

            Canopy:

             Mustang Aeronautics - Rounded Style

             Mustang Aeronautics - T-18 Style

 

 

FLIGHT TESTING THE MUSTANG

 

           Persons intending to fly the tail wheel equipped MUSTANG should have prior tail wheel flying experience.  The two characteristics of the MUSTANG that would tend to cause difficulty are common to all small aircraft - this is directional sensitivity on the ground, and also sensitivity of the elevator control.  This sensitivity is completely forgotten by MUSTANG flyers after a few hours flying, but it does require attention on initial flights.

 

           A smooth sod runway is preferred over a hard surface for two reasons.  First, the direction al sensitivity is practically eliminated.  Secondly, the landing roll distance is reduced to about half that required on a hard surface runway.

 

           A few taxi runs at high speed are recommended.  During these taxi runs the tail should be raised two or three inches. Slow initial acceleration is desirable.  On a hard surface runway 1400 to 1600 RPM will be sufficient as air speed should not exceed 50 MPH.  Slightly more power will be required on sod.  One caution - Due to slow acceleration the right rudder used to counteract torque effect is fed in gradually , and in most cases is un-noticed by the flyer. The effect of this is that if the throttle is cut abruptly the flyer finds he is holding right rudder which is not needed., and immediately overcontrols with left rudder - thereby making " s " turns down the runway.  The throttle should be reduced slowly to prevent this.

 

           I definitely recommend that you lift off and land straight ahead on the runway several times prior to full flight.  I believe the best method of performing these lift offs, as it eliminates the need for attitude and control changes is as follows:

           Accelerate down the runway using a intermediate amount of power (about 1800 RPM) with tail raised slightly off the

ground.  Your taxi runs will have given an idea of how much runway is required to accelerate and decelerate.  Allow PLENTY of reserve runway.  If at this RPM the aircraft does not become airborne, try again using slightly more power. When the plane is felt to be airborne slowly retard the throttle.  As the plane is in the landing attitude it will settle back to the runway and roll out will be similar to a normal landing.  As this type operation is entirely in ground effect you will find the air speed to be lower than anticipated.  These lift offs will familiarize you  with control responses, and also detect any misalignment of the landing gear.

 

           Perhaps the one major difference in landing the MUSTANG as compared to most factory made planes is that the landing FLARE must be made much LOWER than you are used to doing. This is due to the fact that when you are sitting on the ground in the MUSTANG your eye level is much lower than in most standard type aircraft.

 

           As a safety precaution in case of a unplanned go-around it is suggested that the plane be fully ready for flight, with sufficient fuel, during these taxi tests.

 

           CAUTION - DO NOT blast down the runway with lots of power and with the stick full back during these tests.

 

           Unless you are an experienced flyer I do not recommend that you simply take off on the first flight without the lift-off experience.  In the event of engine operating difficulty you may need to make a quick return to the field, and would have no real idea as to approach speed, float characteristics, or runway required.

 

           On the first flight feel out an APPROACH to a stall.  This will give you a indication of the stall speed.  Use about 20 MPH additional for final approach speed, slowing to 10 MPH more for a over the fence speed.  I believe the main aspect of the landing, as with any landing, is to break the glide or "flare" as low as possible.  (Remember you are sitting closer to the ground than you are generally accustomed to.) I suggest using a little power for the initial landings, 1100 to 1200 RPM.  This will flatten the glide and give more positive control of the approach.

 

           After the taxiing and lift-offs you will be familiar with the three point attitude of the airplane.  This will make three point landings simple.  The method recommended is to use full flaps and a little power.  Flare out the landing glide as normal, and after the flare set up the three point attitude.  A slightly nose high attitude just hold it there and let the plane settle in.  If your flare is high and you feel the plane is settling too fast an additional 100 RPM will reduce the rate of decent.  If you feel the plane is

floating too far, or wants to "balloon", slack off the power.  I have watched a person make a good landing in a MUSTANG although he flared 12 ft. high, by just maintaining the attitude and regulating the rate of decent with power. He did use a lot of runway however.

 

           As the above described approach using partial throttle (although only a small amount of power) results in a flat approach a clear runway approach is necessary.  A completely power off approach is fine, but things happen a little quicker.

 

           A go-around with full flaps down is satisfactory, and acceleration is quick.  It is not necessary to raise the flaps.

 

           One more comment on the above described three point landing procedure.  The ground attitude is approximately 5 degrees less than the stall attitude.  That is why this method worked well.  However, if you were to become too engrossed in easing the plane down from a too high level off position it is easy to raise the nose high enough to get a stall. Caution should be used in this respect.