PPRuNe Forums - View Single Post - Use of the trim wheel
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Old 9th Jan 2004, 03:43
  #18 (permalink)  
Shaggy Sheep Driver
 
Join Date: Oct 1999
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FFF

I'm talking about your standard elevator trim tab a la Cessna 172, 150, Chippy etc. A seperately hinged cut out in the elevator's trailing edge controlled by the trim wheel. What's a V1 tailplane BTW?

As for the anti-servo type used on the PA28 all flying tail - I've no idea. It probably wouldn't work at all as an elevator in the event of the all flying tail becoming jammed.

It did happen - to that DC3 - on take off (you can't get much lower than that) and the technique saved them. Don't give up so readily!

For the same reason, if you run out of elevator effectiveness (say a badly shifted CG) then full forward stick with full back trim will give max elevator 'down' effect, vice versa for max elevator up effect (assuming you have the physical strength to hold the out of trim condition with the stick - OK on the Chippy but not on heavier types). Why? Think about it; You are holding full forward stick and need more down elevator. What is the trim tab but a small elevator? If you want it to add to the total 'down elevator' force you want it to hinge 'down', just like the main elevator of which it is part. To acheive this require winding on full 'up' trim.

SSD
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