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Re: Navaid Wing Leveller

Subject: Re: Navaid Wing Leveller
From: Graham Singleton <grasingleton@avnet.co.uk>
Date: Tue, 16 May 2000 22:57:49
 <000901bfbbf4$f38112c0$7195cfc2@ilyyzusv>
 <001501bfbc45$77bcf220$29e9b094@prsqahfg>
 <12rHJC-23bnA9C@fwd00.sul.t-online.de>

>How do you know when you have a totally friction free system. Our roll
>linkage seems to be fairly free moving though the pitch seems to be a bit
>stiff (as yet we havent fitted the tailplanes and drilled out the
>counterweights).

Carl, greetings
>Both pitch and roll should be friction free. That means if you knock the 
>stick gently it will continue to move in the direction of the knock 
>without stopping immediately. Obviously some friction is inevitable but if 
>there is significant friction in the pitch direction it will be very 
>difficult to balance the tailplane accurately. If the balance weight is 
>light the plane will tend to oscillate in pitch. (No, not flutter.)


Some of the early supplied ball joints were much too stiff, they were close 
tolerance type. The ball joint should drop under its own weight, or very 
nearly so, when held by the center boss.  The other cause of excess 
friction in roll is to tight fitting of the flanges on the torque tube. 
Those of us who went for a perfect fit with no play had trouble.

Pitch stiffness is usually misalignment of the bronze bushes caused by 
distortion of the fuselage moulding after bonding the bushes in.

Graham , typing with a limp



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