Trim indication

trib · #1 11-10-2009, 04:55 AM

For those of you using the manual, vernier cable type elevator trim, do you have any indication of trim position? If not, is there a method you use to verify or keep track of position? I'm guessing this could be an index on the knob or something similar.

Getting ready for first flight!

Jamie · #2 11-10-2009, 06:09 AM

I don't know if you've considered this, but RAC sells a position sensor that can be used by the EFIS/engine monitor units commonly used in our RVs. You could also install a standard RAC LED indicator for trim position.

Position sensors are at the bottom of this page:
http://www.rayallencompany.com/products/indsens.html

yakdriver · #3 11-10-2009, 06:24 AM

On my 7 take off is the first knuckle of my fore finger. If I have a passenger and baggage it is just forward of that about 1/2 turn. It is really not a big deal and you will find the sweet spot after flying a bit. You will find that from take off, climb and cruise you won't use much more than 1/2-3/4 turn on the trim. Don

Dave Cole · #4 11-10-2009, 06:47 AM

Of course, you only need a trim position indicator for the take off trim setting, as all other trim adjustments are done by feel.

I flew in an RV-6 once that had a take off trim indication marked by a painted ring on the shaft of the vernier trim control. The bulider had filed a shallow groove and painted it yellow so it was easy to see. The nominal take off position was with the groove centered at the point where the vernier shaft exited the housing. The groove was wide enought to see over a range of take off trim settings that might be required for different loading conditions, so small adjustments could be made without loosing sight of the painted ring.

It looked to me like a simple, light, and reliable solution. I intend to do the same on my RV-7.

Steve · #5 11-10-2009, 08:58 AM

I take off with neutral trim (trim tab aligned with elevator). I verify that by looking over my left shoulder before taking the runway.
In cruise, I turn the knob about 1/4 turn clockwise (nose down). You can feel the airplane.
I use full up trim for landing, holding little of no back pressure on the stick.

Randy Hooper · #6 11-10-2009, 09:23 AM

I placed the trim in neutral and marked the shaft at the exit point from the housing. Disassembled and chucked the shaft in a lathe. Made a shallow score which was then painted.
As the ring appears or disappears, trim is approximately neutral.

trib · #7 11-10-2009, 09:33 AM

Thanks guys- between the electronic solution and painting the cable, I'll go with painting the cable. Sweet and simple. I knew someone would follow through with the obvious answer.