How to build a better Swift?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Keshka, Dec 27, 2011.

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  1. Jan 4, 2012 #21

    autoreply

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    I think the Swift is one of the best foot-launchable aircraft around and pretty much at the limit of what we can do with current technology.

    If you want to do a lot better, you need a smaller and lighter wing. The only way I can think of this, while keeping a slow enough stall speed for foot launching is to incorporate a cloth flap.

    Not the normal flap-like thingy, but massive sails that double or triple your wing area for T/O/landing, so you resemble a bat. Sails can be rolled up to the wing/fuselage.

    Another approach is to make hollow ribs, much larger than your wing and slide them outwards during T/O, landing, while being covered with cloth. In cruise you will have a tiny wing and a lot of cloth, folded up in your fuselage. At landing/TO you can winch the ribs until they're spread over your wing and you have something that looks like a deltaflyer.
     
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  2. Jan 4, 2012 #22

    henryk

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    -today SWIFT is the best footlaunched,but not optimal\to long fuselage nase ,great win-tips\...

    http://www.youtube.com/watch?v=W7PvOpk18Hg&feature=player_embedded#!

    -see 1:42 and 2:44 =clothe-flapp-extender!
     
  3. Jan 4, 2012 #23

    Keshka

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    aircar: I may be tough but not that tough! (Laughs) The weight of 155 would be the max I hope for WITH the engine attached. I plan on removing the engine when conditions allow foot launch. Following the lead of the Swift where there engine is also removable.

    good point autoreply how in the heck would you implement something like that on a foot launch able? Do you think the system used on the Swift/Millennium is not adequate?

    Henryk: wow, those cloth flaps are amazing. There is little detail about this from Akoya and from the brief glimpses hard to tell how it all fits together sure increases the wing area.

    Picture0013.jpg
    Picture0014.jpg
     
  4. Jan 4, 2012 #24

    autoreply

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    Good question. The Lisa system is one approach (tiny flap+flap rails, with cloth between them). Another is a true bat-shape, only connected at an extended rib and maybe somewhere on the fuselage.

    The third (hollow, spanwise sliding ribs) might prove to be very effective at tripling the wing area for example. If you only have positive lift, such a system could be extremely light. If I'm correct there was also a plane around WWII with two tiny tandem wings where the same system applied. The hollow ribs were hinged at TE and LE and the cloth tension kept the ribs cross section vertical.
    I have no flying experience with it, but I've read everything I could about them. The Swift seems to be an excellent design that is pretty close to the boundaries of what's possible. So if you want to do better (see your topic title ;)) you'd have to look at other, possibly radical solutions.
     
  5. Jan 10, 2012 #25

    Keshka

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    Yes, I know....I wished I could change the title. What Ihave decided I want to do is build a slightly larger Millennium (5-10 percent)and work to reduce the drag on that. A fully skinned composite wing is morethan I want to tackle. I have contacted Steve Morris and he was kind enough toreply. He cautioned me on the complexity of the project and said no detailedplans or cad info was ever created so not available. I wrote back and explainedmy questions were less detailed than that. What I was hoping for was major dimensionssuch as wing span, cord, taper, winglet size, control surface size, D sparrough dimensions and such.
    Airfoils used: root, tip and winglets.
    Amount of twist and sweep.
    Any layup info on the D spar.
    Photos of the rib folding system.

    If not, then I call to the heavens and invoke the almighty "Rule of THUMB!"

    Keshka

    Beati Possidentes Alis
     
  6. Jan 10, 2012 #26

    ultralajt

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    Last edited: Jan 10, 2012
  7. Jan 10, 2012 #27

    WonderousMountain

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    You may not need to buy all of them, but if you're serious about doing any design work you'll want a couple books to refer to in your personal library. Engineering books are important tools; every bit as valuable as mills, lathes, and various tools for every job. That said, building a proven design will likely be far faster than becoming an aero-engineer.

    Happy building!

    Wonderous Mountain
     
  8. Apr 18, 2012 #28

    ultralajt

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  9. Oct 11, 2012 #29

    BBJCaptain

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    I think that a resurrection of the Millennium would be a great choice. I have been HG since 79 and always wanted a cage rigid ever since I seen a Mitchel Wing. I bought my Millennium in Feb/12 after about a 2 yr search. I think that they only built 50 of these amazing wings and they are very hard to find on the used market these days. The sail would be very easy to get as Wills Wing has the pattern and they will make one for somewhere in the $1500 range.

    One of the areas that needs to be cleaned up is the wing tip covers and the winglet to wing tip junction. It has about an 1.5" gap on the top surface from leading edge to trailing edge. A blended setup that just plugs onto the end of the wing might work better. Also the hang cage junction at the bottom surface of the wing can be cleaned up. If you fly with a full fairing this is taken care of for sure. Steve Morris has told me that the full fairing changes the L/D from about 15-16 to 18-19.

    The ribs are made of 3/8" round tubing that pin (top and bottom) onto the back of the D-tube and are hinged in the center. The trailing edge of the rib is attached to the 3/8" round tubing trailing edge. A cable is attached to a keel at the wing root, through the center hinge on the ribs that goes out to a lever that is pulled outboard and slides into a plug on the end of the trailing edge tube. (each wing) The trailing edge is hinged in the middle and stays together when the wing is folded. There is nothing that needs to be done to the wing to set it up other that spread the wings ( slowly ) slip the trailing edge tube into a v notch on the back of the keel tube, extend the back of the keel ( its about 4" ) till the ball pin pops in place. Go to each wing tip and and pull on the lever to deploy the ribs and plug into the trailing edge plug. Go to the nose and attach the nose catch and the wing the is completely set up!! Then all you have to do is put on the winglets ( with build on rudders ) till a bullet pin pops into place, pin the bottom of the rudder onto the control horn ( for each wing ). Finally pin on the elevons (2 3/16" pins ) and hook up the control cable and the wing is ready to fly. No need to hookup any other cable for the entire wing. One pin per rudder and one bolt per elevon and that is it!!! They did a great job engineering the flight controls on the Mill for sure. Everything else stays rigged and folds up nicely although you have to tie back the control stick before you unhook everything to fold it up. I can have it ready to fly in about 20mins.

    First Trip to King Mt - YouTube

    Rolla
     
  10. Oct 13, 2012 #30

    Aircar

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    Thanks for sharing your flying adventures Rolla, I really enjoyed watching - it looks like pretty forbidding terrain in that region for any outlanding . I was impressed with the aircraft and surprised by how little wing bending was evident -and also surprised by the very far aft position of the pilot as well as the cable 'suspension' for the hammock .

    It would seem that some sort of faired pod would be the first order of business to get some more L/D -- and the Akaflieg Stuttgart SB 13 comes to mind in terms of integrating the pod and wing but pretty much rules out foot launching (unless perhaps the whole pod tilted and the wing was raised enough to let your knees be under neath in flight . My days of foot launching are well past so I would contemplate a pusher prop for self launch as well but realize this breaches your criteria (my Velopter -velomobile based self launcher -in development- matches very similar criteria otherwise .

    if Autoreply reads this perhaps he could be so kind as to post the links to the SB 13 that he sent me a while back --the wing geometry is quite comparable to the Millenium wing with of course higher wing loading and comparable cruise performance to the best standard class gliders --combining retractable sailfoils in such a configuration or something similar could give the best of both worlds (my basic approach with variable geometry to get good climb and cruise as well as unrelated benefits to do with roadability ) The SB 13 suffered ground looping on it's first flight attempts due to the whole wing catching in long grass and being of low inertia anyway so there are lessons to learn from it also (it was not developed further ) -- one of the Horton's test pilots commented that the SB 13 should have been built as a prone pilot design --with the wing being under the pilot's belly and so giving an unrestricted field of view but also being suited to foot launch and keeping the basic balance. There seems to be a great scope for really improving the high speed performance of this type of sailplane without losing the low and slow benefits and you might be the best placed to do it even.
     
  11. Oct 13, 2012 #31

    henryk

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    better solution=wig +fuselage...
     

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  12. Oct 13, 2012 #32

    ultralajt

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    Henryk, aerodynamicaly yes, but not practical anymore for footlaunch ability. This streamlined pod swings (forward/aft) under attachment point of the wing (weighshift).

    As I look at BBJcaptain`s videos... it came trough my mind: "Why even bothering with making something better?" This is good enough, it is foldable, Footlaunchable, slightly less performance that Swift..but aweral is already better if one use in concern easier transporting and surfaces less prone to damage, than of Swift.

    Mitja
     
    Last edited: Oct 13, 2012
  13. Oct 13, 2012 #33

    henryk

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    =weigtshift for tangage\longitudal\ SAM_3768w[1].jpg SAM_3766w[1].jpg control is better\aerodynamically\.

    it works,when velocity is to small,
    it give you possibility of 0-speed landing!
     
  14. Oct 13, 2012 #34
    i think you are still missing the footlaunch requirement henryk
     
  15. Oct 13, 2012 #35

    ultralajt

    ultralajt

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    Yes, footlaunch is essential. Landing can be made on the wheel, no matter the landing speed as far some decent ground is available.

    -------------------------------------------------

    By the way, what you guys thinking about Impact (German rigid wing) with Swift style cage? Probably should fly better than Milllenium... [​IMG] [​IMG]

    Mitja
     
  16. Oct 13, 2012 #36

    Detego

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    You can also fly the IMPACT with a Supine Harness; very similar to that used by Competition Para-Glider Pilots (note - no bulky cages to carry around).

    Attachment only requires a spreader bar, and option rail for better performance.

    [​IMG]
     

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  17. Oct 13, 2012 #37

    henryk

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    IMPACT wing+ good trike=L/D=24 !!! Obraz=SONY-FRIDRICH 012.jpg
     
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  18. Oct 15, 2012 #38

    autoreply

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    [video=youtube;qbYX_evY9aA]http://www.youtube.com/watch?v=qbYX_evY9aA[/video]

    The Akaflieg Karlsruhe is also designing a flying wing sailplane now, lots of updates if you dig a bit deeper.
    Why not sweep the wings forward? Solves most of your problems, you can use flaps, visibility is much better etc.
     
    Last edited by a moderator: Mar 20, 2019
  19. Oct 16, 2012 #39
    I think that the classical reason for not sweeping wings forward is that they flex in unhelpful manners. The X-29 did "clever things" with composite layers to stop this but I dont know if that technology can be scaled down for this weight(?)
     
  20. Oct 16, 2012 #40

    autoreply

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    Yes. Once you've done the math, it's only a matter of orienting your fibers differently (negative bending/torsion coupling). The Concordia sailplane has it, as are several other composite ships are rumored to have.

    In metal that's extremely hard, but in composites... not so much I think.
     

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