Elevator trim

aarvig · #1 08-10-2009, 10:22 PM

I've read the threads about electric vs. manual elevator trim and it seems to be a matter of preference. I am wondering if anyone with manual elevator trim would post a pic of their finished cockpit installation. I am wondering if anyone has tried installing a manual elevator trim with a different setup than the installation Vans recommends (it looks like it may get in the way of the legs). Any opinions regarding the manual installation would be appreciated.

Mel · #2 08-11-2009, 06:47 AM

Not sure which RV you have, but my RV-6 has been flying for over 16 years with the manual trim installed per plans and has never been in the way. The only thing different about my installation from the plans is that I eliminated the vertical panel from the fuel selector to the panel, but the trim is in the same place.

hydroguy2 · #3 08-11-2009, 06:57 AM

I plan on moving my manual trim to the left, under the throttle quadrant(also on the left). Here's a couple of VERY rough planning/staging photo's. I'll be rerouting the cable and fabbing throttle mount first, then trim mount.

RV7ator · #4 08-11-2009, 08:59 AM

Two RV-7s I've built had the standard Van's manual cable installation. The loop from the knob around under the spar doesn't really get in the way, but the knob poking up over the fuel valve and the edge of the mount plate may prove annoying to your legs if you sprawl a bit. The loop simply looks sloven.

So the current -7 has the knob between the seats facing forward positioned over the spar carry through. It's a nightmare fitting it in so it looks good, easily functioned, the seat pans are removable, and the cable clears the nearby roll trim mechanism. The knob still can be a knee banger, and you might tickle your passenger's thigh, but overall it's a more compact installation than standard to my way of thinking.

The current project will have electric pitch trim. The manual works well, but there is enough lash in the cable to move the trailing edge of the trim tab though several degrees, which will bounce you around the cockpit if it were suddenly deflected through the range. The electric installation won't have any lash. This lash might be contributing to the Dynon autopilot pitch trim difficulties I and others have experienced, and it makes fine tuning the manual trim a bit touchy, though it does seem to hold once set.

John Siebold

gasman · #5 08-11-2009, 10:36 AM

Quote:

Originally Posted by RV7ator

The manual works well, but there is enough lash in the cable to move the trailing edge of the trim tab though several degrees, which will bounce you around the cockpit if it were suddenly deflected through the range.
It makes fine tuning the manual trim a bit touchy, though it does seem to hold once set.

John Siebold

My manual trim is installed per Van's and don't have any problem with lash in the cable.
But when you move the cable from the location on the plans, and move it farther back like between
the seats, then you make s turns to fit the cable that is now too long, this will cause play in the cable
that you won't get if you install with only one bend as per plans.

kiwipete · #6 08-12-2009, 05:26 AM

Another thing to consider is if you have a fuel pump for FI in front of the manual trim buy the RV8 cable as it's slightly longer.

I have a manual trim and wouldn't swap it!

Peter

L.Adamson · #7 08-12-2009, 06:57 AM

Quote:

Originally Posted by kiwipete

Another thing to consider is if you have a fuel pump for FI in front of the manual trim buy the RV8 cable as it's slightly longer.

I have a manual trim and wouldn't swap it!

I've heard from many who wouldn't swap from manual trim also.

However, I have electric trim for both elevator and ailerons on the stick's hatswitch. It has been working extremely well!

L.Adamson --- RV6A

RV7ator · #8 08-12-2009, 07:37 AM

Too long a cable is not a problem. Have Van's shortened by a Cablecraft dealer, or order a custom unit. Contemplate the weight you save! he said while munching a doughnut.

Having tried this route, I don't recommend the 'tween-the-seats installation because of its complexity, which changes nothing of the functional characteristics of the manual, only appearances. KISS.

BTW, Gasman, the belts are boxed.

John Siebold
Boise, ID

aarvig · #9 08-12-2009, 03:43 PM

Thanks for the advice and photos. I like the left side throttle and cable installation. Looks good! I have heard from many as well that they would stick with manual over electric trim as well. I have also flown an RV-7A with electric trim and for the life of me I could not trim it out, it was so touchy. Maybe that is just the pilot and not the plane but I felt I was chasing the trim the whole flight.

L.Adamson · #10 08-12-2009, 04:10 PM

Quote:

Originally Posted by aarvig

Thanks for the advice and photos. I like the left side throttle and cable installation. Looks good! I have heard from many as well that they would stick with manual over electric trim as well. I have also flown an RV-7A with electric trim and for the life of me I could not trim it out, it was so touchy. Maybe that is just the pilot and not the plane but I felt I was chasing the trim the whole flight.

On the other side of the coin, I've had comments on how well my 6A with electric trim for roll and pitch.......... trims out. I initially thought about
the speed controllers, but it doesn't need them. BTW, my aileron trim is the piano hinge type on the aileron (servo controlled). This is the "old way", with no bias springs.

Personally, I prefer working trims from the stick, rather than reaching down between some "fat guys" sweaty legs..

L.Adamson