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Thread: Thoughts - wing from one supplier attached to fuselage from another supplier...

  1. #1

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    Default Thoughts - wing from one supplier attached to fuselage from another supplier...

    The recent sale of the Kitfox from the badass high action Jonas team combined with the concurrent Jonas new design/build of Defiance and the Patey build of Scrappy has me thinking… I do not know the FAA laws and that may kill this thought, but here it is.


    With the new vision and freedom of truly custom built designs, I see an unfilled huge opportunity for custom fuselage/cage specific suppliers and for custom wing specific suppliers. With the wing / cage connection design an agreed constant (Beta / VHS), it would be possible to build a perfect plane from dozens of custom non related suppliers. We are already doing this with props, engines, gear box, gear, tires, brakes, panels, why not have options for inter-changeable fuselage/cages and wings and feathers. Cable control will probable be easier than pushrod with so many variables.


    My custom build would start with a wider cage for sure - I am a bigger guy and I want more comfort - I am so tired of the skinny 60’s era side by side shoulder width - I will give up speed to have more a little more width. Im not interested in stol competing so for power an Edge 120-150ish would be fine. I do want to drop into rough places so I would want a stol wing for sure with flaps, larger feathers for better slow speed control, and nice TK1 gear and big Alaska tires and Beringer brakes for ground control. All my flying would be local so a climb pitch prop wins over cruise - ground adjust is fine. I like to camp so I need a larger baggage area and it would be great to be able to flatten out the seats (or detach backrest) and suspend a sleeping pad inside. Im a tech guy so the panel would be full Garmin glass. I do not care about exterior shine, so the cover job would be single color oratex - whatever color is on sale that day wins.


    If I could acquire a wide cage from Jonas or Patey or other and a stol wing with flaps from Steve I would start tomorrow. Third party inspection of welds and build would be on my list.

    The wildcard and mild barrier to entry is the cage jig. A true square box frame can be home built with the right skill set and tool box or can ordered from any respected precision machine shop and delivered on flatbed anywhere - this would be the starting point for a square jig. Once the new custom cage jig is final set inside the frame box, source the tubes precision with perfect fit ends from a local CNC shop and you are in the custom cookie cutter cage business. At the end of the day, the cage jig is king - no cage, no nothing.



    As I said at the top, I do not know what FAA rules say about this buffet style build. What are the regs on building the core plane (fuse/wing/feathers) with components sourced from more than 1 supplier. Would each finished build need a type cert?

    In the biking world, it is now very popular to buy a naked carbon frame, and add every single component from rims to tires to brakes to seat to pedals to chain to gears to hub set, to handle bars - everything - to build a truly custom one of a kind bike.


    This user controlled and defined build may be the direction we are heading. Question is would you do it - would you buy a cage and wing from different suppliers just as you do a engine and tires now. With the bush designs this is easy, others including plastics not so, but for the space we are playing, I think this may be an option.

    Just a thought.

  2. #2
    Senior Member jiott's Avatar
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    Default Re: Thoughts - wing from one supplier attached to fuselage from another supplier...

    I would not do it unless I was certain that the proper engineering had been done for the whole assembly, not just the bolted connection points. You will notice that the Pateys do a thorough engineering analysis of loads and stresses before they do any manufacturing. If you have the capability of doing this, then go forward; if not, then stay away from it. I am speaking of safety critical structural items, not the ordinary type modifications. I know not all will agree with this, and you can certainly get by without engineering analysis, but you better know exactly what you are doing and the risks involved. In the experimental category the FAA will let you pretty much do what you want in the design area without checking for engineering as long as you follow approved methods of construction; that's why the 40 hours test period without passengers.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

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    Senior Member rv9ralph's Avatar
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    Default Re: Thoughts - wing from one supplier attached to fuselage from another supplier...

    I suggest reading FAA AC No: 20-27G, Certification and Operation of Amateur Built Aircraft.

    You can build almost anything, if over 254 pounds it will need certification (under that weight it qualifies as an ultralight). One thing that has changed in the last 20 years is the use of parts from certificated aircraft to create a "frakenplane", this is not usually acceptable to the FAA. 51% of the aircraft must be amateur built to qualify as EAB. The checklist to confirm this is in an appendex of the AC.

    Hope this helps to start your research.

    Ralph

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    Default Re: Thoughts - wing from one supplier attached to fuselage from another supplier...

    Not sure the market is big enough for a number of manufactures to build major parts of the plane seperatly. Right now the wait for a Kitfox kit is about 1 year. What if there were 2 identical companies producing Kitfox kits. Would there be any wait at all for a kit then? Maybe not. JImChuk

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    patrick.hvac's Avatar
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    Default Re: Thoughts - wing from one supplier attached to fuselage from another supplier...

    The manufacturing of components is not difficult or particularly expensive for a KF style plane.
    Lots of shops would turn out a custom fuse if you gave them a proper drawing. The challenge and cost is the design/engineering.
    As mentioned in posts above this is a little different than bolting parts together that have compatible fasteners.
    Most builders are not fabricators by trade which is why (in my opinion) the KF is so popular and successful. It's is assembled not constructed.
    What you are suggesting can absolutely be done but I believe you will have a hard time finding a market to resell without solid testing and engineering.
    People will be trusting their lives to your engineering and credibility is everything in this space. Accidents are public and investigated.
    KF has a great safety reputation and I doubt they would endorse any sort or partnership that could jeopardize that.
    But if you look at the Piper cub space for example, you can buy a fuse and wings from many different vendors with a decent level of known compatibility.
    The success of the Mackey line comes to mind but also lends to the reputation and credibility piece. Guy is a legend, just like Patey.
    This is the beauty of the experimental space. If you want to fabricate your own design go for it! I expect it will take a decade or so before the design has a reputation that attracts buyers though.
    🇨🇦CANADA
    Flying | SS7 | G3X | Edge 912

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    Senior Member jmodguy's Avatar
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    Default Re: Thoughts - wing from one supplier attached to fuselage from another supplier...

    Not sure if this is a guaranteed fact, but I have heard that there are only 2 experimental aircraft that have had a full structural analysis completed on them. One being the Starduster Too.
    Jeff
    KF 5
    340KF

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    Senior Member efwd's Avatar
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    Default Re: Thoughts - wing from one supplier attached to fuselage from another supplier...

    Would it not be a requirement for certification when Kitfox started building SLSA versions?
    Eddie Forward
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    SS7, 912iS, Garmin G3X

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    Default Re: Thoughts - wing from one supplier attached to fuselage from another supplier...

    Are you willing to sit in a tandem cockpit? If so then everything you're asking for is already available in the Super Cub world. Numerous suppliers providing their version of wider cockpits, two doors, flat floors for sleeping arrangements (if you like sleeping on a hill that is). Float kits, engine choices, cowling, landing gear, you name it. Go crazy. It's like barbie dolls, Harley Davidsons or AR-15s depending on your age/gender/interests.

    Since most/all of them adhere to the basic formula of the original Super Cub it would be possible to mix and match components from various suppliers (YMMV).

    It's called "experimental" for a reason, which is to allow design innovation. As pointed out by rv9ralph, you'll have a hard time using parts from certified aircraft, but the 51% rule can easily be met through mix & match.

    I haven't kept up but you used to be able to buy various Piper fuselage kits from Wag Aero in full welded, tack welded "knock down" form or just the drawings and a bunch of tubing. Or head to any of the various companies that will sell you beautifully complete fuselage and wing kits to your order. By the way, their Wagabond is side by side and has a camping friendly floor.

    What you're asking for is something that in my world is called an interface control drawing, and it's not a crazy idea. Early Kitfox and Avid Flyers could swap parts because they had the same DNA.

    Not sure if this is a guaranteed fact, but I have heard that there are only 2 experimental aircraft that have had a full structural analysis completed on them. One being the Starduster Too.
    I'm quite sure the Europa is another one. I like to point it out as an example of something that was thoroughly designed but not exactly a raging success. I actually love the original design with its monowheel gear because it is cool, innovative and clearly a clean sheet design but it doesn't fit my current needs. My day job is aircraft design/manufacturing/analysis/certification. While digital analysis is a great tool, it is very much a garbage in-garbage out tool as well. Nothing wrong with sand bags and whiffle trees. Or a design with a long history of not falling out of the sky.
    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

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    Senior Member jrevens's Avatar
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    Default Re: Thoughts - wing from one supplier attached to fuselage from another supplier...

    Quote Originally Posted by jmodguy View Post
    Not sure if this is a guaranteed fact, but I have heard that there are only 2 experimental aircraft that have had a full structural analysis completed on them. One being the Starduster Too.
    The Thorp T-18 is another (and possibly the first?)... designed by a very experienced aeronatical engineer.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

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