servo alignment assist needed
 

I have run into a problem and need your experience and advise. I'm building Kraut's UltraSpadStick and ended up having to using a wider cutout than design in the center of elevators.
As the pics show I need an angled install of the servo, (Two added 1/8" ply shims under the back screws line it up with angled control horn.)
I have the ball links as pictured (4-40 size) which I bought for throttle linkage at carb.

?'s 1) What is the preferred/best method of handling this type of problem?
2) It seems that a ball link mounted to the servo horn would be a neat solution. I have no idea of the proper way or if it is even advisable.
3) Is there a problem with the control horn being off of 90 degrees to the hinge line?

Advise, links all help will be appreciated. I have read a lot of threads in last year but just now getting into scratch/SPAD building

RE: servo alignment assist needed
 

Use the ball link on the servo... and have the pushrod connect to the control horn with a Z bend. Have the main rod on the inboard side of the control horn. (reduces the angle a little)

The horn not being directly above the hinge line wil just give a "differential" throw. With the horn behind the hinge it will pull more effectively than it will push. The big problem comes if the horn is so far back that the pushrod binds when it hits the hinge before you are at full push deflection. When the rod hits... thats as far as the surface is going to deflect.

You can correct for the differential at the servo, by having the arm offset the oppsing direction, the same angle. (this would aggrivate the binding problem above...)

RE: servo alignment assist needed
 

I agree with what FH has said, but I don't understand why your control surface horn has to be that far out on the elevator.
Dennis-

RE: servo alignment assist needed
 

Not sure about the design of this SPAD, but will you be using 2 elevator servos? Must be a big plane.
I doubt anything you do will make that big of a differnce. Just be sure both elevators throws are the same in both direction.
You could make another stab with smaller cutout. Then trim your rudder up to clear.

RE: servo alignment assist needed
 

Why don't you move your Rudder servo to the top of you fuse just in front of the V-Stab and use a Pull ,Pull and you could then move the elev servo to the upper hole giving you more down throw.

Just a thought;)

RE: servo alignment assist needed
 

Do you have a computer radio? If you do, you can change the ATV for both up and down to achieve the desired throws.

RE: servo alignment assist needed
 

Just hook the darn thing up the way it is. Fer cryin out loud, you're building a SPAD and you're going to get anal about pushrod angles?

RE: servo alignment assist needed
 

Man I hate it when I miss key and lose a reply.[>:]

RE: servo alignment assist needed
 

Is that just a drill out of holes(s) in s arm and bolting on with 2-56 bolt? Just have never seen it done, but my opportunities are limited.

Attachment will be directly above hinge, it was the angle being off 90 degrees (6-8) that was the concern.
Location is outboard due to making the rudder cutout larger due to a folding problem and material availability restraint. The plans http://www.spadtothebone.com/SPAD/ultraspadstick/ use 2 std servos for the elevator.

I really appreciate the time that you fellas take to share your knowledge even if it is going in a SPAD. If I don't learn here, I won't learn locally.(Poco Espanol para mi!)

RE: servo alignment assist needed
 

This is a BAD practice... correcting a mechanical PROBLEM with computer adjustment.

If you can't mechanically get the correct throw, adjusting the computer throw is just asking for mechanical failure.

RE: servo alignment assist needed
 

What are you talking about? Of course it is a good idea to use your computer transmitter to make travel volume adjustments - within reason. It is a SPAD afterall. Use some common sense when using your radio to adjust ATV, you can't fix everything. Don't over do it. Add too much and you'll reduce the power of the servo.

Sometimes the only way to make servos react equally in both directions is to use a computer.

RE: servo alignment assist needed
 

Problem with "use common sense".... common sense is uncommon. And... this is the BEGINNER's forum.. where the guy doesn't have the experience to base the "reasonable" judgement on.

Therefore... fixing it with the computer is a VERY bad idea.

RE: servo alignment assist needed
 

Thanks fellas! It is a done deal.
Z's at the horns per suggestions. 5/16" dowel extensions, put the shims (CA to perimeter 3/8" wide mount) under the rear servo screws.
I'm going with conventional attachment to servo arm.
Chronical thread of this project is started and will continue to share the project and lessons learned. CHILI PEPPER MX in spad section http://www.rcuniverse.com/forum/fb.asp?m=1482820&key=

RE: servo alignment assist needed
 

Fuhber --- Ya right.