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Guest lionheart777

Shuddering at 220+ KIAS

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I am tuning my aircraft design prototype and having a problem now with shuddering at roughly 220 KIAS, dependent at times on boundry layer as well. It didnt exist until I lightened her up in the fuel tanks and such. Would anyone like to test fly it and see what they think it might be? I have it at http://groups.yahoo.com/group/fs2002professional/ if you should wish to fly it around the patch. The powerplant is a turbo prop, and I have been trying to get her to cruize at apprx. 300 KIAS, but she is holding at around 245 KIAS and is having trouble holding position on the ground with full brakes at 'low idle' setting at the turbine throttle quadrant. (main panel is King Air, set up with single engine layout). She was almost set at 300 KIAS cruise, and I did some readjusting to the weights which were way off, (set up for King Air, and this plane is scaled with the Piper Meridian).Your help would be greatly appreciated.Bill

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Hi Bill,Changed the pitch and roll MOI's a little,;Moments of Inertiaempty_weight= 2560.000empty_weight_roll_MOI= 4217.000<----------empty_weight_pitch_MOI= 3400.000<----------empty_weight_yaw_MOI= 7460.000empty_weight_coupled_MOI= 0.000max_gross_weight= 4500.000It behaves itself now, all axes are stable at airspeeds up to 300 KIAS.

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Thanks Douglas. I would really like to know how you did it? How such tuning is calculated. If you could explain some time, I would be grateful. My chat email for yahoo is socrates112@yahoo.com I am on now and then, hanging out in the yahoo hanger.Be well and take care.Bill

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