Building A Replica Aircraft. Part Three Construction Details Wings and Covering

Transcription

1 Building A Replica Aircraft Part Three Construction Details Wings and Covering

2 The human brain is a wonderful organ. It starts to work as soon as you are born and doesn't stop until you get up to deliver a speech." -- George Jessel, American actor

3 Brief Review After obtaining a partially complete Graham Lee 7/8 scale Nieuport 11 project I decided to reconfigure it to resemble a 1929 Boeing F4B-2 US Navy Fighter. Boeing developed the F4B in mid 1928 at company expense as a small light weight fighter for the US Navy. The -1 and -2 s had a unique structure as the fuselage was bolted/gusseted aluminum tubing. Wings were all wood (in fact the last of the wooden wing fighters in the Navy).

4 F4B-2

5 Objectives Utilize as much of the original project as possible. All modification must not compromise structural integrity. Keep as light as possible don t go overboard on detailing! Maintain the look of the Boeing with out becoming anal. Have some fun!!

6 Lower Wing The lower wings would require an increase in the bottom chord to fit the profile of the F4B. Drawings were developed of the lower wings with F4B outlines within the original span dimensions but with an increase in chord.

7 Lower Wings Began construction by first deconstructing existing lower wings and salvaging Spars and some ribs.

8 Lower Wings To more accurately portray the F4B new ribs of a longer chord where required.

9 Lower Wings The wing tips were fabricated next.

10 Construction Lower Wings

11 Construction Lower Wing Modified Strut mounts to accommodate N strut. Attempt to remove camber from lower wing

12 Lower Wing Construction Modified rib construction from the spar aft

13 Upper Wing Removed sweep out of wings and modified wing tip shape Another departure from the Graham Lee design. I decided to construction the wing in three sections rather than the two in the plans. 1. Simplify field assembly should I decide to transport aircraft by trailer. 2. Incorporate Access/Inspection panel to make aileron controls more accessible. 3. Incorporate plug-in wing attachments by using 3 nested tubes in main and 2 in the aft spar. 4. Allowed a more manageable way to establish the proper angle of incidence of the main wing.

14 Center Section Construction

15 Top Wing Panels The top wing panels were also deconstructed. Most of the original wing ribs, compression struts and fittings were reused, however, new spars were procured and installed. As with the lower wings, new wing tips were constructed to reflect the wing profile of the F4B.

16 Top Wing Panels Utilized the Center Section to Jig the inboard spars while locating and installing Compression Struts and Drag/Anti Drag cables Using Tip Bow to determine length of rear spar.

17 Top Wing Panels Cut and fit spars to wing tip and temporally fasten with Clecos. Repeat for Left Side Panel

18 Top Wing Panels Hung wings to locate N strut fittings without having to work around wing ribs and wing interior structure. Could only work one side at a time due to shop size but hung left top panel on airframe to even load on the center section.

19 Struts Next step was to level the top wing then set the dihedral in the bottom wing. With that done I use masking tape to visualize the struts and the needed placement of the various fittings. The resulting dimensions were transferred on to strips of plywood to further determine lengths and angles needed in fabricating the struts.

20 Struts

21 Top Wing Panel

22 Top Wing Panel

23 Top Wing Panels

24 Top Wing Panels

25 Pre-Cover April 2013 Assembled all components to check fit, angle of incidence and dihedral. Final drilling of struts and fabrication of all flying/landing wires followed.

26 Pre-Cover Removed wheels to establish a more stable airframe and also allowed the short guy to better reach the upper wing! (Should have thought of that earlier!) 237 pounds

27 Pre - Cover May 2013

28 Covering Dilemma which covering process to use : Poly Fiber the standard for many years Stewart s touted as eco friendly Oratex new process to the US no painting. Pro s All use a polyester fabric Poly Fiber has the largest user base and instructions are excellent and has a large selection of colors. Stewart s utilizes water base glues and finishing materials and most if not all of the same selection of colors as Poly Fiber. Oratex utilizes a water base adhesive and the finish is precoated. Finished weight is as much as half as much as Poly Fiber

29 Covering Cons Poly Fiber uses volatile materials that smell and can be hazardous to health. Stewart s doesn t smell as bad but still induces fumes when sprayed that prolonged exposure should be avoided. Poly Fiber and Stewart s would require investment in equipment and facilities I did not own (namely good quality spray equipment and a finishing booth). Oratex has limited color availability and doesn t produce a wet look finish. Limited instruction manual. Materials are more expensive than equivalent from Poly Fiber or Stewarts.

30 Covering Decision Oratex No exposure to hazardous chemicals. Available colors matched my needs. A wet finish would not be appropriate for a 1930 vintage replica. No need for painting equipment, paint booth, extra lighting, dust free environment, etc. (i.e. avoided expense). Significant savings in installed weight and work effort.

31 Empennage (Tail Group)

32 Empennage (Tail Group)

33 Lower Wings

34 Lower Wings

35 Lower Wings

36 Upper Wings

37 Fuselage

38 Fuselage

39 Wheels

40 Covering Details Empennage 56.5 hours 2.6 lbs Wings Fuselage Wheels Total hours 17.7 lbs Poly Fiber (med. weight) Estimate 42.6 lbs My original Oratex 6000 estimate (w/o wheels) 17.3 lbs Weight 25Lbs or 5% of 475 projected empty weight.

41 Snack & Chat April 2014

42 Initial Weight and Balance May 1, lbs as shown Projected empty Gross 750 lbs

43 To be Continued! What are you Building? If Not, Why Not?