Thoughts on trim tab layout

[dlomheim]

I am sloooowly continuing the rehabbing of the RV-3A I bought last summer and have just about fixed all the issues I found with the empenage. The last item I am mulling over is how the original builder routed the elevator trim tab. He ran a 1/4 plastic pipe through the elev. horn shaft and then ran a wire through that hooked up wheel a wheel on the left side of the cockpit. A problem I have with this installation is that at certain points of elevator movement the trim tab wire gets a bit tight and won't easily allow tab adjustment.
I was wondering if anyone else has type of arrangement, or if this is unique to this build...

Doug

[https://www.dropbox.com/s/ivq3c880qcqvjgh/Trim tab wire.jpg?m]

 

[gasman]

What you have there is NOT good. Remove the plastic tube and wire from the horn, and repair the horn. Install a trim cable as per the plans.

 

[Larry DeCamp]

Trim cable routing

Doug, Gasman's suggestion is a good one. I checked mine, built per plans, and the difference is the large hole on the elevator SKIN and SPAR gives much more room for the cable to bend than the small hole in your elevator horn.

 

[Ab&DaniRV-3]

elevator trim cable

what you have there is one of the early trim systems. I am building from plans from 1976 ... (#321). The cable and sheath are routed through the elevator horn as your pocture shows. A clevis end bolts to the elevator horn,and a 3/8 dia. tube butts up against the clevis with a spring and cotter pin against a bracket rivited to the elev. side. In case a trim system failure the spring will push nose down trim on the elev. . Very simple in design and inexpensive to fabricate. I made that for mine, according to the plans and seemed to function just fine. But i have removed it and installed a elect. trim system. Gotta use the buttons on the control grip for something.
It looks like yours is a sold wire... Vans supplied a 1/8 in. plastic tube with a small dia. cable with clevis end.

 

[dlomheim]

Electric Trim

...But i have removed it and installed a elect. trim system. Gotta use the buttons on the control grip for something.
It looks like yours is a sold wire... Vans supplied a 1/8 in. plastic tube with a small dia. cable with clevis end.

Removed mine as well and posted a picture in the "show us the status of your project" page. I thought that it must have been in the plans originally since my neighbors old "3" also was built that way! Now to to finish up my firewall clean up and get the engine mounted again!

Doug Lomheim
RV-3 #513 (Under restoration)
RV-9A FWF / electrical / Canopy gluing (awaiting attention)

 

[Ab&DaniRV-3]

I just love all the freedom we have to manufacture and build our AB aircraft. I cann't do that with the cessnas that we have. Even though the old trim system functions well, It is a good idea to upgrade if you can. So many cool gadgets to work with! There are now several RV's here in south east Idaho. What a great Airplane.