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Continue launching the rotor while the run.

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  • Continue launching the rotor while the run.

    It is often believed that continuing the launch during the rolling would shorten the takeoff distance. But this is because it is assumed that the same torque continues to be applied on the shaft until takeoff rrpm. Therefore the power delivered by the launcher is increased due Power = Torque x rrpm. So, the result is favorable. But comparing the methode with the same launcher power, then the pre-launching rrpm at rest is lower, due to the lower ratio of gear, and also the thrust of the propeller is reduced because of the power substracted by the launcher. In this case, the distance gain is almost zero:

    Assumptions: Pre-launch at 260 rpm and shaft to 24 , rotor inertia 52 kg.m2, rolling drag in the grass = 5%, parasitic drag S.Cx = 0.39 m2, rotor at 0.6 R above the ground, prop thrust: 1400 N (static) 1150 N at 60 km/h. . Only 93% with launcher.
    Last edited by Jean Claude; 03-14-2017, 06:09 AM.