Manual Trim Question

WingsOnWheels · #1 11-12-2009, 11:48 AM

I would appriciate if a manual trim owner (in or out of the plane) could do me a favor.

I need two bits of information:

1: What does one knob rotation equate to in linear movement of the control (ie. 1 turn = XX inches)

2: What is the total linear range of the manual trim stop to stop.

That is all. Thanks!

Randy Hooper · #2 11-12-2009, 02:23 PM

In the airplane, I get 2 1/4 inches of full travel with 10 turns. So just under 1/4 inch per turn.

Frank Smidler · #3 11-12-2009, 04:01 PM

I haven't really documented it, but I believe I never use more than a total of 2 or 3 turns at the most during various flight modes (TO, Cruise, LD, Light, Gross). I'll have to check it out during my trip to Milwaukee this weekend. I do know that it is very sensitive in cruise and just barely turning the knob to the point of break-out force (maybe 5 degrees) is all that is needed for adjustment as fuel is burned forward of CG. It also seems to have a wide dead band, i.e. once adjusted a tap of the stick can cause it to either stabilize at a slight climb or slight decent of a hundred feet/min or more.

WingsOnWheels · #4 11-12-2009, 09:53 PM

Thank you very much for the information.

The reason for asking:

I'm not a small guy by any means (6'4" and not a bean-pole). I like the manual trim, but cannot have the trim control mounted above the fuel selector and I am not adding a center console. I am thinking of alternative methods to drive the manual trim.

Thanks,

Colin

pierre smith · #5 11-13-2009, 05:53 AM

...my Air Tractor has a simple pushrod that rides in grommets in the holes of the vertical side supports and has a simple lever in the cockpit that you move backwards for up trim, forward for down. You could modify your cable by removing the knob and fabricate a vertical lever with spring-loaded friction and mount it on the left side.

Regards,

RFazio · #6 11-13-2009, 06:35 AM

What we did on our 6 was to use the standard trim cable that came with the kit and route it through the spar as shown on the plains. But we did not wrap it around to head back towards the pilot. It just poked out through the spar and stopped there. We made a little housing for it and the fuel selector. the adjustment knob faces forward and is down below the top of the spar. It works perfectly and is totally out of the way. We did not want to use the center channel between the panel and seat pans. There are pictures of my interior on my site if your interested.

JonJay · #7 11-13-2009, 09:28 AM

Quote:

Originally Posted by RFazio

What we did on our 6 was to use the standard trim cable that came with the kit and route it through the spar as shown on the plains. But we did not wrap it around to head back towards the pilot. It just poked out through the spar and stopped there. We made a little housing for it and the fuel selector. the adjustment knob faces forward and is down below the top of the spar. It works perfectly and is totally out of the way. We did not want to use the center channel between the panel and seat pans. There are pictures of my interior on my site if your interested.

This would be counter to the standard "push - nose down, pull, nose up". I am sure you would get used to it, but it is backwards is it not?

Colin - You could set your trim up like the 3 and 4 with a lever to the side of the cabin. I have seen this on others.

RFazio · #8 11-13-2009, 01:29 PM

There is no in and out really, cause your turning it slightly. My side down is trim down, myside up is trim up.

JonJay · #9 11-13-2009, 02:48 PM

Quote:

Originally Posted by RFazio

There is no in and out really, cause your turning it slightly. My side down is trim down, myside up is trim up.

It does go in and out slighlty, but only a small amount when you are making cruise adjustments so I will buy what you are selling. I know others have done this before. If it was a throttle or mixture, might be another case!

WingsOnWheels · #10 11-13-2009, 11:07 PM

There are a lot of good ideas here! I like the lever idea, simple and easy to fab. My idea is quite a bit more complicated, a simple lever might be the best bet.

I was thinking of making a trim wheel (think Cessna but without the wound cable). The trim wheel would use a worm gear to drive a simple rack connected to the push/pull cable. The worm drive would keep the trim from slipping out of position and provide for fine adjustment like the "stock" control.

Something like that, I haven't thought it through in to much detail yet...