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  1. #1
    Co-Pilot jetlag's Avatar
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    Is it the wing or the trike which moves in turbulence

    F-JRIB
    Today is the tomorrow you worried about yesterday.

    Phil.


  2. #2
    Airfield Ops Diyan's Avatar
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    Judging based on the pendulum effect and the law of physics, the trike moves more and gives you the felling/sensation/experience of "turbulence". The wing is merely flying through turbulent/disturbed patch of air and by design copes in a way with the turbulent conditions to the best of its abilities. It's all down to the wing type/design/tech specs.

    Just my opinion following logics and the physics law. Someone should correct me if I'm wrong.

    I hope this helps.

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  4. #3
    Co-Pilot jetlag's Avatar
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    I pose the question to promote discussion that would help me and also others better understand turbulence and what is happening to the wing and the trike, the impression is that it is mainly the wing that does the dance, but like you I suspect it is the trike. I imagine those with hang glider experience will know better the truth as they as closer to and probably better associated with the wing itself
    F-JRIB
    Today is the tomorrow you worried about yesterday.

    Phil.


  5. #4
    Co-Pilot Peter Twissell's Avatar
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    Some basic physics:
    When the aircraft enters turbulent air, there is a change in the angle at which the wing and trike meet the air. Both will experience acceleration due to the change in the force vector. The wing has relatively little side area, so a change in yaw angle will have relatively little effect on it. The trike has a larger side area, so a change in yaw angle will have a more significant effect. Conversely, the wing will experience large changes in force due to changes in pitch angle, while the trike will be relatively unaffected.
    Thus, if the turbulence were to consist of purely rising or falling air, we would expect the wing movement to dominate the pilots perception. If the turbulence were to consist entirely of horizontal shear, we would expect the trike to dominate.
    It is only in wind tunnel tests that we can isolate specific changes in the airflow relative to the momentum of the aircraft and investigate these effects separately.
    In reality, turbulence consists of changes in both yaw and pitch angle of attack (relative to the aircraft) and the motion of the wing and trike will be the result of the combination of forces.
    G-BZNP Still not dead

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  7. #5
    Co-Pilot jetlag's Avatar
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    Thanks for that Peter. I think I may have to read it a few times for it to sink in but I get the gist of it.
    F-JRIB
    Today is the tomorrow you worried about yesterday.

    Phil.


  8. #6
    Captain MadamBreakneck's Avatar
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    I do hope a flexwing instructor and/or designer comes on here to answer that question. my own theory is that the wing resonds predominantly to the aerodynamic forces induced by the turbs, and the trike responds predominantly as a heavy pendulum to resulting movements of the hang point.

    Then there is the coupling between the two dependent on how nervous the pilot is and how strong the pilot's arms are.

    Prof Gratton on here?

    Joan - who couldn't fly a flexwing to save my life as proven by the BMAA flexwing simulator


    Back to just bimbling


  9. #7
    Airfield Ops newflyer17's Avatar
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    There is also this vid.
    Although again I don't quite understand what it shows.

    https://youtu.be/XFeesro-arc


  10. #8
    Co-Pilot Peter Twissell's Avatar
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    As Joan rightly points out - after the direct aerodynamic effects, there are the effects of the pilots response, which can range from the ability to smooth out all the forces into a perfect landing, to a series of delayed over-corrections leading to a messy go-around or a messier arrival.
    I remember reading somewhere (Propellerhead?) that an aircraft flies not because of the pilots intervention, but mostly despite it.
    G-BZNP Still not dead

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  12. #9
    Co-Pilot jetlag's Avatar
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    I have read that somewhere Peter that a flex will fly itself and the pilots job it simply to **** things up. I have been instructed to allow the wing pretty much full movement in flight and use my arms only to damp out the moves a little obviously taking a more active roll on take off and landings. Easy to say but for low hours pilots, as car drivers, the death grip is evident. I have now 200+ hours and I am beginning to think I now have a basic understanding of my machine and beginning to relax the death grip rather well, but it is through this very video and the editing of it that I think I have had something of a eureka moment in my understanding of the action/reaction of the wing and trike which has again helped me in my latest flight to relax even more, I flew 2 hours yesterday and had to land as I had lost all feeling in both my thumbs on a day with early ground temperatures at 0C and lunchtime ground temperatures up to 14C causing the wing to do its crazy dance

    Phil
    F-JRIB
    Today is the tomorrow you worried about yesterday.

    Phil.


  13. #10
    New Member speedfreak's Avatar
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    Trike hardly moves unless in super crappy conditions. Its mostly the wing. I flew in turbulent winds last week. I was calm and able to watch what the wing was doing. Keep just a light grip on the bar with thumbs resting on top of the bar with your fingers. Let the wing do its thing! Andy


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