| Disclaimer: I recommend that you DON'T try this setup. You could be hurt or even worse, killed. If you choose to build and fly experimental aircraft then you also choose to accept the responsibility for your own injury/death. I told you not to try this, but I know how some of you buzzards are, you'll eat anything. ;-) | |
My trim system installed on a
Z-Himax. The tab that I have is 17" wide and 3" deep. This just so happened to
be what I had to work with. Trimmed for level flight the tab is deflected down approx. 3
degrees. Your CG would be the modifying factor here. |
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| An overall view of the trim
system. If I had figured out all the details before covering the elevator I would have
embedded it inside for a much neater installation. |
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| The trim tab control horn setup.
I used and 6/32 allthread as the drive shaft. The control arm is threaded for the 6/32 and
is attached to the control horn with an AN bolt with a small bushing inside the horn to
allow the control arm to turn. The stops are just there just in case of a motor runaway.
(fuse the line accordingly) |
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| The drive
motor is a small 12v dc type with a gear box. This one came out of a rotating mag
mount caution light. They can also be picked up at some "scientific" suppliers
or out of motor salvage catalogs. Cost 6- 10 bucks. This motor has the 100 rpm gearbox.
The 6/32 shaft is coupled to the out shaft by a prop adapter off an R/C electric motor .
Available at your local hobby shop. Bracket from AL and attached to the control horn
gusset |
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| DPDT momentary contact switch in cockpit. Push down on the switch trim nose up, switch up for nose down. Think of it as a small joy stick. One second burst either way is a good way to trim up. I have it on the left side of the panel but wish I had put it on the right for convenience of working the throttle and flying by wire. |  |
| Final notes: The system has no position indicator but it's not really needed. The butt will tell you all you need to know in flight. I was really surprised at how little trim was needed on the Hi-Max over its entire flight envelope. You may trim for a long climb or decent with just a couple jogs of the switch. I have even transitioned from climb to cruise to approach, all by wire and rudder. If you have a radio in your craft you can listen to the little motor sing as it works too! (You may have to back the squelch off a bit) I would be interested in hearing from anyone who has ideas on improvements, etc. Safe Flying, Alan D. Jones |
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