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Thread: Help- mathematical results for a banked turn

  1. #21
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    Help- mathematical results for a banked turn

    Your correct Paul,

    I am struggling to relate the maths with the facts but I now think I see what you are saying is the maths is correct but it takes the plane into a place which is impossible to do.

    I understand the G is produced by the lift but if the forces are of a greater magnitude than the static 1G downwards which can be produced by the centrifugal effect ( speed / radius ) then it acts through the mass/lift axis which could be at any angle, even upside down???

    I am afraid what my head says is that when its at 90 degrees the dominant force is due to the centrifugal load which is dependent on the speed and radius of the turn , push out more G. Obviously too stay level you would need to fly at less than 90 degrees to offset the gravity.

    Not enough brain cells left , more drink needed

    :burger:

  2. #22

    Help- mathematical results for a banked turn

    its still all down to lift - even at 90 degrees of bank - it's the lift that is producing the turn radius and the G. And in this context lift is the force the wing is making - not the vertical component - which at 90 degrees can only be zero!

    There was some weird stuff earlier in the thread about not being able to roll out of the turn at 90 degrees due to gravity pulling the trike / hanglider pilot out of Perpendicularity with the wing. That's not really relevant and the angle the trike adopts has no effect on the wing - it's roll torque applied by the pilot through his / her arms to the bar that produces roll force to the wing.

    Paul

  3. #23

    Help- mathematical results for a banked turn

    Wasn't it you Paul (could have been BB) who worked out it was impossible to load a flexwing beyond 4G because of unloading due to airframe distortion?
    Dave

  4. #24

    Help- mathematical results for a banked turn

    Depends on the individual machine and its aeroelastic coefficient. We plotted the curves from flight testing stall speed against g for the kiss 400 and Va ( the speed where you ca get 4g without stalling first) was above Vne.

    But types with a higher sail tension don't twist off so much under load and can pull more g.

    Paul

  5. #25
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    Help- mathematical results for a banked turn

    Found this on my quest

    Web page of bank/loads

    Stall speed doubles at just over 70 degrees and trebles at just over 80 degrees which probably explains why we cannot pull High loads.

    We just cannot go fast enough

  6. #26
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    Help- mathematical results for a banked turn

    Dave Smith wrote: Wasn't it you Paul (could have been BB) who worked out it was impossible to load a flexwing beyond 4G because of unloading due to airframe distortion?
    Dave
    The BHPA test rig has managed to produce figures well above 4G on some wings, but others shed load. It's not flight though as the ability of the rig to load the wing is limited mostly by engine power overcoming the drag at those high lift values.

    Think the highest figures ever sustained without failure on a test rig are close to 7G. Think this was on the US test rig in the late 1990s.

    Mark Dale ran the rig most of the time but current Tech Officer Ian Currer also has some experience on it, and used to be a flex wing manufacturer.

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