I'm building a Lippisch ground effect vehicle with it's wingtips almost touching the ground, but because of torque effects the left wing actually does touch the ground, so it can't lift off. It even can't go straight. Adding ailerons isn't an option because this problem has to be solved on te ground (zero speed) and not in the air (because it doesn't get there). Does someone know something how I can solve this problem?
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1$\begingroup$ In what way is torque affecting things? $\endgroup$– Jon StoryCommented Dec 8, 2014 at 23:44
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1$\begingroup$ It is actually the reaction of the spinning propeller and motor who causes this problem $\endgroup$– Simon RavelingienCommented Dec 8, 2014 at 23:51
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2$\begingroup$ Is a contra-rotating propellor an option? $\endgroup$– Jon StoryCommented Dec 8, 2014 at 23:53
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2$\begingroup$ Now you're getting into small scale engineering, and out of the scope of the SE site, but I would have thought a bit of gearing would get you where you need to be $\endgroup$– Jon StoryCommented Dec 9, 2014 at 0:24
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3$\begingroup$ can't you put low-friction skids under the wingtips? and maybe even launch off a low-friction surface? $\endgroup$– rbpCommented Dec 9, 2014 at 0:33
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2 Answers
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The Lockheed U2 had the same problem (bicycle wheel base and they had to prevent one end being dragged on takeoff).
They solved it by adding "pogo wheels" that self detach on take off. (the ones on the orange sticks.)
(source wikipedia)
answered Dec 8, 2014 at 22:59
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The commenters are right: Either use two separate propellers (left and right) which turn in opposite direction, or use a counter-rotating prop.
This picture of a P-38 shows the principle. You can drive both props from the same engine by using driveshafts or belts. The Wright flyer had such an arrangement.
On small airplanes with very big engines a gearbox with concentric driveshafts is driving both propellers in opposite direction.
A simpler way to have contra-rotating props is to put them at opposite ends of an engine pod.
In all cases the prop torque is reduced to zero, or in case of the podded arrangement, almost zero.
answered Dec 9, 2014 at 7:24