jeffmoreau

jeffmoreau

Well Known Member
I am setting up the electric trim tab on my RV8A. Is there a particular amout of up and down (in degrees) that I should aim for.
I couldn't find anything in my instructions or on the drawings.
Any help would be greatly appreciated.
 
I am pretty sure that Trim Tab Deflection is in the same table where you'll find the deflections for the other control surfaces - it is not obvious - somewhere in the Flight Test section maybe? I don't have the book handy, but it's in there....

Paul
 
Trim Tab Please Help

Hasn't anyone on the net set up a trim tab on a 8.
Please help.
 
Last edited:
jeffmoreau said:
Hasn't anyone of the net set up a trim tab on a 8.
Please help.
Click to expand...

Jeff,

I believe the electric trim system is the same for all airplanes. The electric motor shaft runs from one stop to the other and the tab should be centered when the motor is about half way through its range of travel. That's about where mine is and works well.
 
trim tab travel

Jeff
These guys are right. I'm just in the phase 1 testing but I'll tell you it does'nt take much trim to get to a hands off fight condition Just a few pulses and you're in trim. I've noticed that in landing trim the tab is maybe 15-20 degrees out of the intrail position. If you build it like they want you can only get so much travel, but its plenty.

Jeff Riblet
RV-8
643RV
 
Trim tab

I have a 9A, but I think this applies to everyone. Mine is manual trim. I have my cable adjusted so that full aft trim brings me to best glide speed at engine out.
This allows plenty of trim in the other direction.
Also, for new airplanes, try this. Trim your airplane off in perfect level flight at your chosen cruise speed. Land without touching the trim. If you see a big deflection in the tab, you may want to consider shimming the HS up or down to achieve a slick tail in trim. I got a couple MPH out of this, and it trims and flies great.
I assume you should be able to adjust the Mac servo in a similar fashion to achieve best glide, but don't know for sure.
Just a thought to chew on...

Regards,
Chris
 
jriblet said:
Jeff
These guys are right. I'm just in the phase 1 testing but I'll tell you it does'nt take much trim to get to a hands off fight condition Just a few pulses and you're in trim. I've noticed that in landing trim the tab is maybe 15-20 degrees out of the intrail position. If you build it like they want you can only get so much travel, but its plenty.
Click to expand...

Since you're still in Phase 1, you may not have expanded your CG envelope all the way forward and aft yet - when you do, you'll find that you will come close to running the tab all the way in both directions. This is the nature of tandems....you need more trim range because the CG changes so much more than with side-by-sides.

Paul
 
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