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Wing Can Expand To Fly Really Slow For Short Take-Off And Landing

 2 years ago
source link: https://hackaday.com/2021/07/10/wing-can-expand-to-fly-really-slow-for-short-take-off-and-landing/
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Wing Can Expand To Fly Really Slow For Short Take-Off And Landing

[Mike Patey] had made a name for himself by building high-performance experimental aircraft. In his latest project, he added a transforming wing that can extend its chord by up to 16 inches for low speed and high angle of attack performance.

The aircraft in question, a bush plane named Scrappy, has been attracting attention long before [Mike] even started building the wings. Designed for extremely short take-off and landing (STOL) performance, only some sections of the fuselage frame remain from the original Carbon Cub kit. The wings are custom designed and feature double slats on the leading edge, combined with large flaps and drooping ailerons on the trailing edge. The slats form an almost seamless part of the wing for normal flying, but can expand using a series of linkages integrated into each precision machine wing rib. Making extensive use of CFD simulations, the slats were designed to keep the center-of-lift close to the center of the wing, even with 50 degrees of flaps. Without the slats, the pilot would need to use almost all the elevator authority to counteract the flaps and keep the aircraft’s nose up.

Leading-edge slats have been around since before WW2, but you don’t see them used in pairs like this. Aircraft like Scrappy will never be commercially viable, but innovation by people like [Mike] drives aviation forward. [Mike]’s previous project plane, Draco, was a large turboprop bush plane built around a PZL-104 Wilga. Sadly it was destroyed during an ill-considered take-off in 2019, but [Mike] is already planning its successor, Draco-X.

Posted in Transportation HacksTagged aviation, bush plane, experimental aircraft, mike patey, piston engine, scrappy

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47 thoughts on “Wing Can Expand To Fly Really Slow For Short Take-Off And Landing”

  1. Gravis says:

    Those whole people being water balloons in a flying hunk of metal seems dangerous enough. Building your own flying contraption just seems like tempting fate. Physics is not kind to us water balloons; we pop.

    1. smellsofbikes says:

      In the 1980’s there were five times as many homebuilt aircraft registered per year as commercial aircraft in the USA.
      Now that companies like Cessna are selling lots of light aircraft again, the numbers aren’t as skewed: there are more homebuilts registered per year than any commercial aircraft company sells, but the total number of aircraft built by Cessna et al is greater than the number of homebuilts, barely.
      There are a _lot_ of homebuilt aircraft in the sky and the vast majority of them do very well.

      1. David Siebert says:

        Cessna and Piper are not selling a lot of light aircraft. I will bet that more new homebuilts are flying every year than manufactured aircraft. I think you will find that average age of manufactured light aircraft is getting higher all the time. at least in the piston market.

      2. GekkePrutser says:

        A new C172 costs at least $250.000 so home building or buying used is still the only option for people :)

        1. GekkePrutser says:

          “For many people” I meant.. Seems to be no way to change my post.

        2. How much are people building home builts for $250k to not be an option?

    2. Hirudinea says:

      Hey, when it’s your ass on your line you tend to be pretty good with safety, or dead, very Darwinian.

      1. smellsofbikes says:

        It’s depressing how many very talented designers and builders end up dead when their aircraft come apart because they made mistakes.
        I’m thinking specifically of Steve Wittman here, who was one of the most experienced designers and pilots in history.

        1. LordNothing says:

          its not really my place to tell people what risks they should and shouldn’t take. i don’t like it when people tell me i shouldn’t do something because its risky. best i can do is tell them what i think the risks are and let them make up their own mind.

          as for those aircraft designers, they don’t exist to be your personal idol, they live to build aircraft. if they die doing what they love then thats a good death. its unfortunate, especially when all that was needed was a second set of eyes to tell them that something wasn’t right with the aircraft. i suppose they could play it safe and die in obscurity doing something they dont much care for with their lives. or worse, delegate the risks to others. let the bold be bold.

        2. Payton brown says:

          Steve Wittman died unfortunately because of a fabric covering mistake. It had nothing to do with the design of the plane.

    3. Steve Beaulieu says:

      If God had intended man to fly…..

      1. Fosselius says:

        He would have given humans a curious and creative mind.

        1. Criatura says:

          And the ability to actually do it. Wait…

    4. cyrax says:

      My father built many planes over the years.

    5. cyberteque says:

      you can apply that “reasoning” to just about any kind of fun

      ever seen a drag car come apart?
      a rally car?

      most fun is at least a little dangerous

    6. Criatura says:

      There are thousands and thousands and thousands for homebuilt aircraft flying around.

      “Currently, more than 33,000 amateur-built/homebuilt aircraft are licensed by FAA. They represent proven aircraft designs that have been flown safely for many years.”

      More here: https://www.eaa.org/eaa/about-eaa/eaa-media-room/experimental-aircraft-information

  2. geocrasher says:

    Mike Patey is one of those rare people who have the golden trifecta: Time, Money, AND Brains, all at the same time. I love his enthusiasm.

    1. Régis says:

      By time we need too understand that he is sleeping a few hours by night like 2 or 3.

    2. Chris says:

      Now just consider what the world would look like if more or most people had the resources to explore what interested them. It’s a shame we’ve been convinced that the resources of the world should be concentrated into the hands of the greedy and unimaginative and the masses should be held perpetually on the brink.

  3. smellsofbikes says:

    This is really cool. Double slotted flaps are pretty common, especially on large aircraft, but double slats are unusual.
    For a time, a lot of designers were building aircraft with auto slats that popped out as a result of air pressure when the angle of attack was high enough that flow separation was starting, but that had issues when one opened and the other didn’t because of slight differences in lift (particularly exciting in low speed turns during landing) and the resulting asymmetric lift was Very Exciting.
    Since then, people have spent a fair amount of design time trying to ensure lift augmentation devices deploy and behave in a symmetric manner, and the higher the lift augmentation, the more important that symmetry becomes.
    My STOL friends concentrated on more power and wingtip extensions. This is a far cooler and more ambitious route of development.

    1. fiddlingjunky says:

      From my reading (theory of wing sections, Perkins&Perkins, a couple other less rigorous books, all referencing NACA studies), it seems like slats don’t add anywhere near as much to absolute lift as slotted/fowler flaps do, but help a ton in delaying separation. I can’t watch the full video now, but I’m interested to hear what Mike expects to gain from the slats, I doubt it’ll give an absolute lift increase as extending chord by the equivalent amount would, but it could enable a wing with a longer chord to hold onto lift down into STOL speed regimes and AoA a lot better.

  4. George says:

    Out of curiosity.. why aren’t these things first designed and testing on an RC plane and then scaled up? Seems quite risky to just do some simulations and #yolo a plane together

    1. Dude says:

      Because the power to weight ratio of a scaled down RC plane is vastly different, and the Reynold’s number is not scale invariant, so the aerodynamics behaves differently.

      1. Anonymous says:

        Tell that to Heinrich Dorfmann, “Flight of the Phoenix”, 1965 version. :)

        1. cyberteque says:

          he would understand that some stuff does not scale well, if at all

          his “lift enhancement devices” complained a LOT

    2. Greg A says:

      neither the mechanical nor aerodynamic factors really scale directly. you learn about as much from your RC model as you do from knowing that a boeing passenger jet also has leading edge slats. it’s not nothing but it’s not a direct validation of your engineering.

      i don’t say this because i think it’s reasonable to test it on a crewed airplane…rather the opposite. testing this enough to have decent confidence in its mechanical characteristics, let alone its aerodynamic ones, is a real beast of a problem!

    3. CW says:

      Things don’t scale like you think in fluid mechanics.

    4. Steven Clark says:

      RC planes can let you get away with murder. It’s more or less possible to hot glue a receiver, brushless motor, and some servos to a sheet of foam core and expect that it will actually fly, if poorly.

    5. three_d_dave says:

      Despite the comments – NASA does this frequently. The Reynolds number effects are typically for the transition from laminar to turbulent flow and scales linearly with size and velocity for constant density and viscosity. Building a 1/2 scale R/C plane is certainly within reason and the difference in Reynolds number is not significant. The tougher part is matching the airspeed and AoA as the weight of the scale model will decrease by a factor of 8 while the wing area decreases by a factor of 4.

      OTOH – one can apply the exact same simulations for the 1/2 size plane and use the 1/2 size plane to determine any deficiencies in the simulation so that those can be corrected and improve the chances the simulation for the full size plane will be representative.

      The reason they aren’t doing this is that they aren’t going to instrument the full sized plane or any other test article because doing that is very expensive – a factor that NASA, doing basic research has to do. There’s little point to making a model if there’s no data coming from it. At best they might determine a useful CG range.

  5. Cree says:

    This guy does have so much knowledge and so much money – yet he can`t afford to buy a simple clip-on mic? I find it really hard to understand what he is saying because of the acoustic properties of his hangar… come on. But also: THIS IS SOOO COOL! I have been watching several DRACO vids in the past, what he (and presumably, his team) achieves on a regular basis is astonishing!

  6. Dude says:

    How about swiveling the whole wing forward to control where the center of lift is.

    1. David says:

      That’s what I was thinking. A longer rear flap and pivoting wing should be much simpler aerodynamically than actuating and keeping front and rear flaps smooth.

      1. geocrasher says:

        You’d be dumping all the lift you created to equal out the forces. Instead, he equals them out by adding MORE lift instead of decreasing it. If you watch the video, he explains it clearly :-)

        1. Criatura says:

          Also, fuel is in the wings, so shifting the entire wing would require a lot more force when moving it forward against the drag by the air and the weight of all that fuel.

  7. Truth says:

    Very smart, but I look at the wing and one thing goes through my head “complexity is the enemy of safety”. Yes day one this thing will work exactly as expected, but how about after a year or two years of wear what are the failure modes and are they all safe. I have no idea how many are planned but I’m guessing about ten of fifteen of these devices per wing with at least eight to ten moving parts in each so that would be about 160 to 300 moving parts.

    On the flip side if this works very well I could see it being fully embraced by commercial plane manufactures, because wings then become a replaceable part (¥¥¥/€€€/£££/£££), that needs to be inspected and serviced before failure.

    1. Truth says:

      I watched the followup video and he appears to be using two on each side of the wing for four in total, which is less moving parts than I would have expected. But I guess these would only be used during takeoff and landing that there would be minimal shear force on the eight aluminium bars because no turning is involved.

      I typoed above it should have been (¥¥¥/€€€/$$$/£££)

    2. I disagree with the validity of “complexity is the enemy of safety” statement. Automation greatly enhances safety in thousands of applications in our daily lives.

      1. Truth says:

        How about if I add three word “in mechanical systems”, basically more moving parts are more potential single points of failure.

  8. Peter says:

    This is great stuff and I watch all his videos.

    It is not likely that this wing has laminar flow all the way to the end of the flap. The flow stays attached but that does not mean it is laminar, where focus is on low drag for high speed rather than high lift at low speed. Most wings are turbulent flow designs, since even bug splatters on the leading edge can trigger transition from laminar to turbulent flow.

  9. Bob says:

    Is this similar to the large commercial aircraft wings?

  10. Thinkerer says:

    It’s all fun and games until the wing flaps/slats on one side jam halfway through the cycle in a remote area where you only have a short field and have to land slow and steep, or (worse) one is stuck all the way out and the other all the way in (CF the DC 2 1/2 variant: https://cnac.org/aircraft02.htm). I’d hope there is a “partial deployment” option to balance things out.

    1. aki009 says:

      I suspect they are mechanically interconnected, so that if one side binds, the other one stops at the same spot.

    2. Shannon says:

      You always budget additional fuel to get to an alternate runway. If your flaps get stuck you land long, pilots train for these things in good conditions so they know what to do in an emergency.

      1. Criatura says:

        If only people were trained to drive like we are trained before passing our written and practical flying tests…

  11. three_d_dave says:

    Interesting pitch.

  12. Bob says:

    Really should have model the table slightly to the left for the first image so it doesn’t say ‘crappy’ on the aircraft

  13. fho says:

    One of the recent Omega Tau Podcast episodes was on the MILAN project they have a similar aim, but use a computer generated flexture inside the wing that deformes precisely between two shapes.

    [1] https://omegataupodcast.net/371-automatische-profiloptimierung-und-milan/

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