Telescopic Wing Design

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Spencer Fisher, Nov 6, 2019.

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  1. Nov 6, 2019 #1

    Spencer Fisher

    Spencer Fisher

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    I've been thinking of some out of the box wing designs for am UL/LSA aircraft. Ideally I'd have an extremely low stall speed but low drag at cruise speed. I think some sort of hybrid wing design could accomplish this task.

    Here's a link I found thats close to my idea (for a larger aircraft but the idea is the same)
    http://www.geversaircraft.com/ac/telescopicwing.htm
     
  2. Nov 6, 2019 #2

    Topaz

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    Here's one that actually flew: https://en.wikipedia.org/wiki/Akaflieg_Stuttgart_fs29

    The consensus was that, while the telecoping wing was the best solution from the perspective of pure performance (compared to area-increasing full-span flaps) for a sailplane, the extra complication and pilot workload to actuate them wasn't worth the small gain in performance.

    It's not a bad idea at all. It's just hard to implement in a way that's simple, reliable, and easy to use.

    Oh, hey - welcome to the forums!
     
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  3. Nov 6, 2019 #3

    Spencer Fisher

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    Thats honestly kinda what I expected. But I've got some time before I have space and money to really begin anything so designing is where I am right now. Thanks for the link I'll have to check that one out! And thanks! I've been lurking for a few months but haven't created my own thread until today.
     
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  4. Nov 7, 2019 #4

    BBerson

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    The Detroit Flying car had telecoping wings for road use. Unique spar.
    Crashed on takeoff. (unrelated to the telescoping wing, I think)
     
  5. Nov 7, 2019 #5

    pictsidhe

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    Weight could be an issue too.
    Extending flaps would be a lot easier to implement and probably lighter. Some of them increase the chord by 30%. Have a look at Fairey-Youngman flaps as well as airliner and carrier fighter high lift systems.
     
  6. Nov 7, 2019 #6

    Topaz

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    Telescoping wings do more than just increase area. They also increase span and aspect ratio, which can have a dramatic impact on climb and gliding performance.
     
  7. Nov 7, 2019 #7

    ScaleBirdsScott

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    I gotta think an electric extension vs using a handcrank would at least reduce the pilot workload aspect.
     
  8. Nov 7, 2019 #8

    Tiger Tim

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    There was also the Makhonine Mak-10 and Mak-101 in France in the 1930’s with variable span wings.
     
  9. Nov 7, 2019 #9

    Riggerrob

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    Many people have patented telescopic wings, but none seem to have perfected them to production standard. Maybe we are just waiting for new materials.

    Zeng Ming published a paper on "Airplane morphing by radical geometry change...."

    He covers all the above mentioned concepts, plus inflatable wings and swept wings that change wing root area depending upon different phases of a flight. Much of development of inflatable wings for ultralights --was done in Switzerland.

    Another option is the retractable biplanes built in Russia during the 1930s. Their retraction mechanisms were frightfully complex. Their lower wings retracted into upper gull wings. Main landing gear retracted into lower wings. Interplane struts also disappeared when lower wings retracted. When fully folded, they were gracefully streamlined, gull-winged monoplanes. When extended, they almost doubled wing area to land slowly in short fields. They proved flyable, but were not competitive with the latest Polikarpov Biplanes and monoplanes.

    An ultralight could vastly simplify retraction methods if you don't mind extra struts exposed in landing/long wing configuration. I am picturing a biplane with a single surface (top skin only) top wing with a full-depth lower wing. That configuration might also work on a telescopic wing with lift struts bracing the outer wing panels.
     
  10. Nov 7, 2019 #10

    Aerowerx

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    Several years ago, wasn't there someone that made a "wearable" tailless glider with telescoping wings. The purpose was that he could fit them in the launch plane. IIRC it was a c-130. After jumping out the back door he extended the wings. and sailed around for quite a while.
     
  11. Nov 7, 2019 #11

    Doggzilla

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    If your goal is to have both good cruise and low stall, a flapjack is far easier to design.

    https://en.m.wikipedia.org/wiki/Vought_V-173

    It’s almost exactly as fast per hp as a Cessna or Piper, but takes off and lands at like 25 knots.
     
  12. Nov 7, 2019 #12

    Topaz

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    There are more things in avation, Horatio, than are dreamt of in your philosophy. Cruise and landing speeds are not the only and exclusive metrics of airplane performance.
     
  13. Nov 7, 2019 #13

    Doggzilla

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    Well it’s a good all-round design, you have to admit.

    Pilots returned good reports.
     
  14. Nov 7, 2019 #14

    Riggerrob

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    Nikitin-Shevchenko built a pair of folding biplanes during the 1930s. They used complex pneumatic systems to actuate wing and undercarriage folding mechanisms, but the pilot only had to worry about a single lever. The lever only had three positions: 'wings up', 'wings down' or 'wings and wheels down.'
     
  15. Nov 7, 2019 #15

    Topaz

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    Actually, no. I don't. The point of my last post that there are more aspects of aviation than just cruise and stall speeds. The V-173 would make a lousy seaplane, long-range aircraft, motorglider, or low-power design.

    There's no such thing as a good "all around" design. That's a gross oversimplification.
     
  16. Nov 9, 2019 #16

    Spencer Fisher

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    The flying flapjack design is interesting but imo one of the ugliest things I've ever seen. Having some kind of lifting body would be cool however and probably help make this sort of design possible. I do think sticking to the kiss principal is probably best. Over complicate it and something will break and I don't want anything screwy going on with my wings. Extendable flaps would be another possible solution and really if all I really wanted at the end of the day was a stupidly low stall speed I think that would be fine.
     
  17. Nov 9, 2019 #17

    Riggerrob

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    Dear Aeowerx,
    Modern wing suits allow skydivers a 3/1 glide ratio, the same as ram-air parachutes. The biggest wing suits can fly formation with the smallest parachutes ... and this is contact formations!

    OTOH both wingsuits and small parachutes are more sensitive that Pitts Specials requiring hundreds or thousands of jumps to master.
     
  18. Nov 9, 2019 #18

    Aerowerx

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    Maybe, but what I remember was NOT a wing suit! It was a rigid wing that you would strap on your back. The wing telescoped after jumping out of the plane, to give a larger span.
     
  19. Nov 9, 2019 #19

    jedi

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    But the small ram air parachutes land and the wing suits still use a parachute (most of the time). Is the reason the high induced drag of the low span wing suit or the large area difference? Please explain. Is the parachute at max speed and the wing suit at minimum speed?
     
  20. Nov 9, 2019 #20

    jedi

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    Are you thinking of Yeves Rossy? If so his wing folds not telescopes. See 3:50 in the following video.
    Jetman | Yves Rossy
     

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