REFLECTOR: Slowing down elevator trim speed

nmflyer1 at aol.com nmflyer1 at aol.com
Fri Dec 26 10:45:35 CST 2008


Thanks Al, 

I thought it appeared that way when I wired my G5. I am curious, Is anyone flying with the Tru-Trak altitude hold (stand alone) and the stock trim system?  I have the Mack G-5 and the stand alone Tru Trak Auto pilot (with the out of trim warning light system),  Seems to me, that if it works, you could trim it pretty close, engage the ALT Hold, and you'd be set. 

I had an electric trim on my old Cherokee 180, It acted the same way as you folks mention. Took a lot of tiny taps on the switch to get it right. Then, as soon as you burn off a little fuel, or someone slides their seat back... it would "creep" again. 

Kurt 


-----Original Message-----
From: Al Gietzen <ALVentures at cox.net>
To: 'Velocity Aircraft Owners and Builders list' <reflector at tvbf.org>
Sent: Fri, 26 Dec 2008 9:15 am
Subject: Re: REFLECTOR: Slowing down elevator trim speed






I was told that the Mack grips have this brake in the switching system. Haven't tried it yet, but while wiring them it kind of looks like it. 

Kurt

You are correct.  I have the Mack G5, and the trim switch closes the circuit to ground when you let off the button.  That’s all you can do for motor breaking.

However; at cruise speeds I find that is not enough to avoid ‘over-trim’; and end up tapping up and dn buttons a few times to get a spot for level.  And I would not want slower trim at approach speeds. What we need is a circuit that changes the trim 
speed as a function of air speed, and does it by variable pulse current. Decreasing voltage via resistance may be damaging to the motor over the long term.  

Happy New Year,

Al





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