Ray Allen Elevator Trim Tab trays

[U2fletch]

These trays are riveted to a rib, and bonded to the elevator tube using Loctite EA9394 structural adhesive. They replace the stock servo tab and mechanical trim mechanism.

 

[jim.mclaughlin924]

If I were doing it over, this is how I would go. I would do a rudder trim tab the same way.

 

[SpruceForest]

We did something similar, but use 4130... nice to reduce overall trim system weight.

 

[paulodonnell]

I'm placing just one Ray Allen servo in the tail area of my Patrol to actuate the original trim horn....tail feathers are already covered!

 

[Astro John]

I'm placing just one Ray Allen servo in the tail area of my Patrol to actuate the original trim horn....tail feathers are already covered!

Is the Patrol trim a servo tab? Wouldn't that cause an issue with the trim?

 

[paulodonnell]

Yes I think the Patrol servo tab function should be unaffected (as I'm using the trim motor to just move the original horn in the fuselage) but would have lost that feature had I fitted twin servo motors in the elevators I guess.

 

[Astro John]

I haven't seen the whole mechanism in action. I am guessing the trim horn in the fuselage stays stationary when you move the elevator, and the 'servo action' is caused by the relative position of the tab and mechanism in the horizontal stab?

 

[paulodonnell]

That's correct TJ as far as I know and why the servo is going in that location for me...

 

[rv8bldr]

I put electric elevator trim in my 4A (mounted in the fuselage driving the original trim arms), but instead of a rudder trim tab I just re-used the elevator trim wheel and chain to tension the rudder return springs. I did an article in Beartracks a few years ago on it. I hooked the forward side of the rudder pedals (where the return springs attach) to 1/16" cable that ran through a couple of small pulleys up to springs connected to the trim wheel. The trim wheel is mounted horizontally under the throttle quadrant and you just move the wheel left or right to apply a spring tension bias in the direction you want the rudder to go.

Full disclosure: I am waiting for good enough weather to do my first flight so this has not been tested airborne. However, it works a treat on the ground and my Maule had a factory installed similar design (it only worked for "right rudder", though)

 

[rkennell]

I did a similar installation that Paul did, connecting the servo to the trim horn where the cable was connected. The servo action of the trim tabs is unaffected the tabs act the same as they would connected to manual system.

 

[Have-Purple]

So does this require 2 servos, on for each port and starboard trim tabs?

was planning on a single actuator running both tabs.

 

[rkennell]

I used a single servo. The trim horns are connected just as the would be with manual trim system

 

[FFTravism]

This was the idea I was having but didn't think the servo had enough travel.

 

[rkennell]

(https://bearhawkforums.com/forum/bearhawk-4-place-quickbuild/770-electric-trim-in-a-qb-kit) This is a link to what Battson posted. I used his idea. The travel I have is similar to what he has photos of. I used the Ray Allen T3-12A servo which has 1.2 in of travel. I also have add cross angles braces to the bracket to stiffen the side to side movement of the bracket.

 

[U2fletch]

You have 2 options. If you want to keep the servo tab function of the elevator, you can use the method above by rkennel. That only needs one trim servo. If you want to ditch the servo tab function, you can use the method myself, and others have done with one trim servo in each elevator.