wise wig-craft

Discussion in 'Aircraft & Aviation' started by lizzienewell, Jan 21, 2006.

  1. lizzienewell

    lizzienewell Member

    SCEtoAux came up with this working WIG-craft model on the net.


    It seems John is trying it as well.

    I imported the jpg into Corel and found that the jpg is a bit distorted--it's not quit symmetrical.
    I changed the color and have sprayed it with polyurethan becasue I may be trying it on ice or hardpack snow and need it to be somewhat waterproof.

    I'm eiger to see how John's works along with anyone else who is trying it.
  2. SCEtoAux

    SCEtoAux Member

    I built two of them so far. They scoot along the floor real good. The hook for the rubberband has been beefed up and repaired a few times already.

    Eventually I will try building with two vertical stabilizers using repositional glue to check out different configurations, but that is more like a get-around-to-it type thing. :)
  3. Bowdenja

    Bowdenja Active Member

    Doug..... I was think about attaching two stabs also.

    I cheated and built a smaller version out of scrap balsa I had just hanging around. Still have to attach the launching connector and figure out what weight I need for it, so it has not "hovered" yet.

    Lizzie.... I am going to do one out of paper and give you a distance figure, but it will be in a coupla weeks.

  4. lizzienewell

    lizzienewell Member

    Here is my trial. The rubber band is taped to the kitchen floor with electricians tape. I had to cut the hook slightly bigger to handle a wide rubber band.

    Attached Files:

  5. lizzienewell

    lizzienewell Member

    And she goes across the floor,rises slightly, hits the doorjamb for a total dustabce of 12 feet 4 inches. More or less.

    I need a bigger floor.

    Attached Files:

  6. lizzienewell

    lizzienewell Member

    Next plan--add a central rib/fussalage. The craft will deform less on pullback and also allow a redesign with backsweapt wings. I'm thinking of putting the hook on the back so I can make a shooter out of a yardstick and clothespin. I will be able to position the shooter wherever I want, stand on it, and release the clothespin.
  7. SCEtoAux

    SCEtoAux Member

    Yep, my kitchen is the only place in the house with a hard smooth surface floor. Both of the ones I made scooted across good until they hit the potato bin. The longest distance was around 14' (427cm). They make a slight thunk when they hit the potato bin so there is more distance in them. :)

    Lizzie, sounds like you have some good ideas for modifications.
  8. Gefahren

    Gefahren Member

    about your modifications to the design, I seem to remember from a show I watched on WIG aircraft that they prefered to use a swept-forward wing instead of a swept-back one (or at least something that looked more like an f-15 wing mounted backward). If I'm remembering this correctly (who knows?) it was because the swept forward wings would help prevent the craft from digging the nose into the ground while swept back ones would actually aid it in doing so. I could be completely out of my mind and your making it out of paper, so you can try different ones, but I thought I'd mention it. O, and btw, if you made a bigger one, then it should be able to fly accross carpet too (or snow from looking out your door in the picture)
  9. charliec

    charliec Active Member

    I seem to remember that swept forward wings have a nice property in that when they stall the stall spreads from the root to the tip so the flight controls are effective even when a large part of the wing is stalled. Also the stall behaviour is different from swept back - I think the wing doesn't pitch down at the stall. The downside of swept forward is that they've got to be much stronger (heavier) than swept back because higher loads are carried by the centre section.


  10. lizzienewell

    lizzienewell Member

    The pictures of real WIGs seem to have slightly sweapt back wings. They do have anhedral rather than diahedral wings which means that the wings go down instead of up. That might be what you're remembering.I'll have to try it both ways. Thanks.

    I've built a shooter out of a stick with a clothespin held on by a zip-tie. I tried it outside on the snow, but it only went about three feet befor catching on a rut.
    Then I tried it on the carpet and the dogs got excited and stepped on the model. It's not getting reglued.


    Attached Files:

  11. hpept

    hpept Member

    I like this subject very much and i would like to tell my opinion about aerodynamic. The idea of building a swept wing shoud not be all that efficient as we could think but it surely looks cooler 8). Since we're dealing with low speed devices, it would be better to stick on straight wing (everybody can see that slow fliers like gliders and ultra light aircraft all have a straight wing) due to induced drag (which is bigger on swept wings). It's sufficient to say that the swept wing was invented to help break the sound wall (Mach=1) reducing formation of shock waves on the wing (which add a new kind of drag called "shock wave drag"), which is not our case.... i hope :grin:
    About direction of sweep (back/forward), it causes the lift center (geometrical point where the lift force vector can be ideally applied) to move respectively rear or forward with respect to a straight wing, so with good reason Gefahren said that a forward swept wing should dig less than a back swept one because the lift center is closer to the nose. This is in principle, because we should also know where the center of mass of the vehicle is located, as the lifting force creates a torque around the center of mass and the resulting reaction (nose up/nose down) depends on the mutual position between center of mass and center of lift. Hope this contributes to build nicely working devices.
  12. Bowdenja

    Bowdenja Active Member

    I love the lauching pad Lizzie, got to make one of them myself!

  13. Gefahren

    Gefahren Member

    This is what I meant by a swept-forward wing

    [​IMG] [​IMG]

    Although I'm still looking, I seem to remember that it had alot to do with stability, and allowing the craft to achieve flight quicker without any forward engines blowing air underneath the wings (such as the jets do on the Ekranoplan). Also I remember something about these designs only able to do short hops or jumps out of ground effect, but if you were to straighten the wings out (like in your designs Lizzienewell) then it would become a full airplane.
    These things are real efficient powerwise, the first one pictured did 100km/h on only 13hp

    Edit: Well, I don't know why Imageshack isn't showing the first one... it was of a real airplane that looked close to the drawing.
    Here's the link to the company web site I got those from http://www.airfoil-development.de/ They also have a technical explanation of the ground effect aircraft.
  14. Matthias

    Matthias New Member

    Agreed that the main reason is (pitch) stability, rather than efficiency. A wing in free air has a center of lift farther forward than when in ground effect, and also less lift. If you pitch up suddenly in a WIG, forward-swept wings gets more of your wing area out of ground effect, while the center section gets a little more pressure at the back, helping you to level out? If you have a stright wing, you experience a sudden shift in lift (no moderation with height differences) and can backflip or send the craft into an unstable cycle.

    Maybe an effect with coupling of roll as well? A forward swept wing should lift the nose.

  15. lizzienewell

    lizzienewell Member

    I thought from looking at photos that wings were swept back but here the a top down drawing of the commercially sold craft put out by flightship.
    The wings aren't swept back but they aren't sweapt forward either.

    Attached Files:

  16. charliec

    charliec Active Member

    It looks like a reversed delta to me - should have similar properties to a swept
    forward wing. Although I think the induced drag would be pretty high - this mightn't be a problem in the speed regime of a WIG.


  17. wunwinglow

    wunwinglow Active Member

    I seem to remember the big shift of centre of lift is the reason why the big Russian machines have such large horizontal tail surfaces, and automatic pitch control systems to keep them airborne.

  18. Maurice

    Maurice Member

    That is the reverse delta planform advocated not only by Dr Lippisch but by Roberto and Matthias too.:)
    A lot of information on wigs including some fairly advanced theory on their aerodynamics, hydrodynamics and power requirements, and balanced assessments of their advantages and limitations can be found by digging into
    So far I haven't found comment on their manouverability which basically comes down to how easily they can change direction.
    By closing the airbrakes after flaring to land you can carry on a very very long way in ground effect in a modern glider but significantly changing direction is not really on because you can't bank. (It helps to have a mile long strip of war surplus concrete under you and to give up before reaching the end of it ! ! ! :))
    The ship classification societies are mainly responsible for overseeing construction and operation, might this be on the basis that they need to dodge ships more often than avoid aircraft.:) but see
    for the different possble types of wig.
    Lizzie's organic design looks rather good with swept forward inner wings in ground effect and extensible outer panels for zoom to height for banked turns giving good manouverability.
    And Lizzie may be the first to get to try one out
    Inside Passage may well be an good location.

  19. SCEtoAux

    SCEtoAux Member

    I added two vertical stabilizers to the back of one of the WISE models, giving the model three vertical stabilizers. They were all the way aft and on the outboard edges on each side. The first flight started out good but a few feet from the launch the front of the model came up and stopped the flight. I added a standard size paper clip to the hook and tried again. It scooted real good for about twice as long as the flight without the paper clip then the front came up again. I added a single thickness of cardstock with the same side profile as the hook, holding it in place with the paper clip. The performance improved greatly, even better than the original configuration with just one vertical stabilizer. Perhaps the two extra vertical stabilizers moved the center of gravity too far back and the addition of the paper clip and the extra thickness of cardstock at the hook balanced it better. I need to find a larger space to see how far it will go.

    For some reason the two extra vertical stabilizers seem to improve the formation of the air cushion. Or maybe I had too much coffee.:D
  20. lizzienewell

    lizzienewell Member

    Thank you for the links. I'd seen Pacific Seaflight in the Anchorage Daily News. I started thinking about WIG crafts without even knowing that they existed. Then I saw the article on Pacific Seaflight.

    I misplaced the link when I changed computers. I notice on their link that they have an office in Anchorage where I live. I will see about visiting the office although I expect it is actually the home of the president of the company.

    I think that the same craft would work really well in Cook Inlet. I hope the company does well and then expand. I think that they could charge a high price for tourist tours.

    I think they would be the fastest way to get from Anchorage to Hope or Anchorage to Point MacKenzie. They would also be good from Homer to Seldovia. Cook Inlet has huge tidal currents and is dangerous to boats due to the difficulty with stranding on mud flats. I would think a WIG could travel over a mud flat as easily as it travels over water.

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