Electric Elevator (Aileron too) TrimTo be honest, the manual trim was not in the way for my conversion to single (center) control stick. I just wanted electric trim as it cleans things up a bit. Well actually there is an ergonomic reason for going electric. The manual trim on the left side wall is too far from the center seating to be comfortable. It's a minor point but is the best justification I have. Well that, and all that unused real-estate on top of most control sticks begging to be used. Also gives my right thumb something to do, playing with all those switches (trim, smoke, flaps). I think my thumb is starting to get a superiority complex with all it's new responsibilities.
There is also a slight aerodynamic reason to go with electric trim. The picture below shows the unmodified elevator trim tab. On the right side can be seen how the trim control horn was bent to mimic the angle of the elevator. While this looks cool it actually is bending it into the airstream causing drag and a small amount of trim deflection. Drives me nuts to see this, its gotta go.
The servo hole is located as close to the elevator hinge as practical. I did this for structural reasons as well as to limit the balance effect of a few extra ounces. The cutout is basically as small as I could possibly make it and still insert the servo. By keeping things tight a cover plate will not be needed.
- Click the Picture to see the entire elevator horn.
The wire comes out through a rubber grommet near the hinge and disappears into the fuselage where the elevator cross-tube (my name for the part) passes in front of the rudder.
Important: Don't pull the old bowden cable out right away. It is needed to pull the wire through the fuselage. So carefully attach the wire to the cable upon it's removal.
The trickiest part was figuring out where to cut the hole for the connecting rod. You are on your own here. I managed it with a bit of math as well as eye-balling it. It turned out nicely. The connecting rod is just a length of threaded rod which needs to be cut (shortened) to length.
- Click to see entire image.
Because the servo fit was so tight I had to install it without the threaded rod. Afterward the rod was installed in screwed into place through the small oval opening. Tricky but a workable solution.
RayAllen (RA) has a clever little chart that will help you make the new trim control horn. The servo travel and control horn must match in order to give the correct amount of trim deflection. Here are the parts I useed.
RA T2-7A Servo 0.7" travel
RA RC8-7 Clevis/Pushrod Kit
RA WC3 ... 5 WIRE TEFLON® INSTALLATION CABLE
http://rayallencompany.com/RACmedia/tri ... mputer.pdfAileron trim tab will be done the exact same way as the elevator trim tab.