Fixing Heavy wing

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

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  1. Aug 9, 2019 #1

    BD6

    BD6

    BD6

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    Hello all,

    I have been building a BD-6 for the last 5 years and finally it has flown. It is the first customer built plane flying. The BD-6 is a single place BD-4 designed by Jim Bede. in test flying we have found that it drops the left wing a lot! It took two hands to hold it level. We have added a trim tab to the aileron, rigged the left flap down and are now trying to put trim on the wing tip.
    I am looking for ideas to try to lift the wing, short of changing the AOA of the wing.

    Could use some help

    Tony
    Second BD-6 flying
     
  2. Aug 9, 2019 #2

    BD6

    BD6

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    Here is a picture of the plane
     

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  3. Aug 9, 2019 #3

    BJC

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    Have you accurately measured the twist (or lack of) in each wing as well as the angle of incidence of each wing? If you used a digital level, what is the accuracy of measurement?


    BJC
     
  4. Aug 9, 2019 #4

    BD6

    BD6

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    There is no twist in the wing. it is a strait Hershey bar. the incidence is 3 degrees and the same on both sides by digital level. There is no dihedral.
     
  5. Aug 9, 2019 #5

    BD6

    BD6

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    There is no twist in the wing. it is a strait Hershey bar. the incidence is 3 degrees and the same on both sides by digital level. There is no dihedral.
     
  6. Aug 9, 2019 #6

    BD6

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    There is no twist in the wing. it is a strait Hershey bar. the incidence is 3 degrees and the same on both sides by digital level. There is no dihedral.

    Tony
     
  7. Aug 9, 2019 #7

    Doggzilla

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    It could be many things.

    Does it change when you pull power back and try to glide? That will tell us if its strictly aerodynamic or from the propwash interacting with some surface.

    The rotation of propwash can cause torque if it lines up with any aerodynamic surface. This can be the wings, the tail, or even the windshield.

    Even the shape of the windshield can cause torque if uneven propwash flowing over the windshield causes a vortex to form on one side of the cockpit or unevenly over the top of it.

    So we will need more info. How is it during glide? Does it yaw either with or without power? Does having the windows open effect it? Which one?

    Literally everything that effects the airflow near both wings needs to be checked, no matter how insignificant.
     
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  8. Aug 9, 2019 #8

    BD6

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    There is no twist in the wing. it is a strait Hershey bar. the incidence is 3 degrees and the same on both sides by digital level. There is no dihedral.

    Tony
     
  9. Aug 9, 2019 #9

    BD6

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    There is no twist in the wing. it is a strait Hershey bar. the incidence is 3 degrees and the same on both sides by digital level. There is no dihedral.

    Tony
     
  10. Aug 9, 2019 #10

    BD6

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    There is no twist in the wing. it is a strait Hershey bar. the incidence is 3 degrees and the same on both sides by digital level. There is no dihedral.

    Tony
     
  11. Aug 9, 2019 #11

    Doggzilla

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    Looks like someone is having some connection issues.
     
  12. Aug 9, 2019 #12

    Pops

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    My level building table got bumped and the outer 4' of a geodetic wing had a slight twist of about 2 degrees at the wing tip rib. Leading edge down. In a geodetic wing what you built is what you have. No twisting.
    I measures each rib that was 12" apart with a digital level ( within 1/10 of a degree) and multiplied the degrees of each rib with the arm from the root rib. Got a total for the wing. Then the same for the other good straight wing. Large different number. So I worked out how much I needed to change the total incidence so the numbers matched. Came out I needed to lower the wing rear attach fitting .058" for the numbers to match on each wing. So I took that wing attach fitting off and welded the attach bolt hole up and redrilled the bolt hole the .058" down and it flew hands off. No wing drop in a stall.
     
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  13. Aug 9, 2019 #13

    Pops

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    IF both wings are the same, check the gaps in the ailerons and flaps for being the same. Different airflow thru the gaps of the wing can make one wing heavier
     
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  14. Aug 9, 2019 #14

    BoKu

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  15. Aug 9, 2019 #15

    BD6

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    I REALY don't want to change the incidence. It would be a lot of work, months. The initial test flights were made without the cowl on because the engine mount was shimmed 3 degrees to the right to get the plane to track down the runway. The cowl is now modified and ready for the next round of tests.

    Tony
     
  16. Aug 9, 2019 #16

    BD6

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    I will look at the vans post. I have also built a RV-7A

    Tony
     
  17. Aug 9, 2019 #17

    Doggzilla

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    That could very well be it. If there is asymmetrical airflow over the edges of the fuselage one side can have a vortex from the difference, and this will interfere with the lift. In fact, it will pull down severely, which is why combat aircraft often intentionally create vortexes on their wing roots. But under the wing, that is very bad.
     
  18. Aug 10, 2019 #18

    lakeracer69

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    Where is the plane located, ASH?
     
  19. Aug 10, 2019 #19

    TFF

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    When flying and you have to hold level, are the ailerons in trail or do you have to deflect them? How does it stall with ailerons in trail? It is usually nice to have two identical rig boards. Forget a level, put one on each wing in various equal spots and sight them across. If not identical by eye in each spot, they are off.
     
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  20. Aug 10, 2019 #20

    Rockiedog2

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    Incidence change would be my last move. Lots of opportunities for correction before that. It may very well be a combination of several problems.
    What has worked best for me is don't rush it. Keep flying it for a while and things will become clearer. I don't change but one thing at a time either. And fly that a while before changing another. Patience
     
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