Fixing Heavy wing

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by BD6, Aug 9, 2019.

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  1. Aug 10, 2019 #21

    BBerson

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    Three degrees engine offset might be excessive. I wouldn't adjust engine offset for ground tracking.
    What is standard engine offset usually? I checked the Cherokee manual but couldn't find the engine offset spec.
     
    Last edited: Aug 10, 2019
  2. Aug 10, 2019 #22

    Doggzilla

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    Generally it’s done with the tail. Tails either have asymmetrical airfoils or they have small fixes trim tabs. Every prop aircraft Ive ever flown has had a small tab or asymmetrical tail airfoil.
     
  3. Aug 10, 2019 #23

    BJC

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    Four cylinder Glasairs have 1 1/2 degrees of engine offset, with a straight vertical stabilizer.


    BJC
     
  4. Aug 10, 2019 #24

    Doggzilla

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    For those of you wondering what I’m talking about, here is a picture. It’s very small and easily missed.

    [​IMG]

    Photo by Markus Milliner
     
  5. Aug 10, 2019 #25

    bmcj

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    A few long shots you could watch for...

    1. Is there any twist in the stab or elevator?

    2. Do the ailerons float differently on one side vs the other?

    3. Are your plastic wingtips place exactly equal (incidence)?

    4. Are there any spanwise seams on the upper surface (particularly in the first quarter-chord) that are more pronounced on one side?
     
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  6. Aug 10, 2019 #26

    Rockiedog2

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    The true wings would be my baseline.
    The slab sides can cause all kinds of weirdness. The corners can make lift or spoil(my 701). No dihedral can aggravate wharever is going on. No tendency to right itself.the large offset in combo with slab sides and no dihedral may be setting up a roll/yaw tendency. Big corkscrew blowong on the flat side. The flat sides can cause mistaken perception of roll/yaw problem.Does the nosewheel have an effective centering device? A wandering NW can run a man crazy tol he figures it out.
    You’ll get it.
     
    Last edited: Aug 10, 2019
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  7. Aug 10, 2019 #27

    Pops

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    Having to use 2 Hands to hold the wing level isn't a slightly heavy wing. I have experienced such a heavy wing and got back on the ground as soon as possible. This was caused by different width gaps between the wing and aileron leading edge on the wing. Aileron gap seals took care of the problem. Like Joe said, could be a combination of problems. Having the cowl off may have been part of the problem.

    Used 1.7 deg right thrust on the JMR + a fixed tab on the rudder for fine adjustment for Yaw.
    Your problem is not Yaw, but roll.
     
    Last edited: Aug 10, 2019
  8. Aug 10, 2019 #28

    Doggzilla

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    Yes, there is probably some sort of vortex forming on one side due to uneven prop wash and those slab sides. Such sharp corners are prone to forming vortexes.
     
  9. Aug 10, 2019 #29

    Hot Wings

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    Nice to hear that you have made it to the flying stage!
    I'm kind of jealous because I've got a set of BD-5 wings that Jim said could be used on the BD-6 but I just never got around to buying the plans. To many other projects now........

    I suspect once you get it all sorted out you will enjoy the plane. Boku's link should get you started in the right direction.
     
  10. Aug 10, 2019 #30

    BBerson

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    I think Jim's son told me the BD-5, BD-4 and BD-6 each are different diameter spars.
     
  11. Aug 10, 2019 #31

    Hot Wings

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    Jim told me that the BD-6 and BD-5 used the same diameter center spar but the bend was different. Could have changed on the BD-6 since the college group tried to build one back before Jim died? But it's all irrelevant now - at least to the OP.

    Just the fact that there is a second flying BD-6, to me, is significant.
     
  12. Aug 10, 2019 #32

    Twodeaddogs

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    Go back to basic and carry out a symmetry check with the aircraft absolutely level, fore and aft, left to right. An aileron might be floating up if it is not correctly tensioned. The trailing edge of the wing might be drooped if it is not exactly dead straight. I, as part of a group dealing with a Zenith 601, had the same problem and an error in the building of the wing caused it to have the same symptoms in flight. We took off the affected wing and it actually settled into a more natural position and we had to relocate one bolt and it has flown perfectly ever since.
     
  13. Aug 10, 2019 #33

    bmcj

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    That’s amazing that it flew better with one of the wings removed. :p
     
  14. Aug 10, 2019 #34

    Kyle Boatright

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    Aerodynamics is still a black art, you know.
     
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  15. Aug 10, 2019 #35

    bmcj

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    314F3BE6-C45C-4497-BD87-926190BC0080.jpeg
     
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  16. Aug 10, 2019 #36

    BJC

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  17. Aug 11, 2019 #37

    BD6

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  18. Aug 11, 2019 #38

    BD6

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    The plane is at Hampton NH 7B3
     
  19. Aug 11, 2019 #39

    BD6

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    It is difficult to try things because my test pilot is not always available. Given my test pilot skills, wrecked only one plane, I will wait until he tells me it is ready to let me fly.

    Tony
     
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  20. Aug 12, 2019 #40

    BD6

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    Thanks for all your ideas. I have made a list of the things I wll check and try as soon as I can.

    1. Is the ball centered ? If not trim to center.
    2. I will try pulling back the power to see if the problem is effected.
    3. Check that both alerons are the same and that the gap is the same.
    i will also look at thr flaps to see how they look.
    4. Check the rigging of the alerons. Are they in trail when at equliberium?
    5. Is there any twist in the stab or elevator?
    6. Are your plastic wingtips place exactly equal (incidence)?

    Tony
     
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