My friend has since ordered, received and started construction of his Eagle 2 (with my help) and wants dual aileron servos. Question he wants me to ask for him is how many bays in from the center (root) should the servo be set up?

What ever bay corresponds to the mid point of the aileron will do, although I don't really see the need to go to all that work on a trainer myself. The Eagle 2 has trained thousands with a single aileron servo.

Yes a single servo will all that is needed. But being a hobby, and in this case a building trainer aswell. The strip ailerons can be controlled by 2 servos mounted beside each other, for programing experiance. The servos could be moved out to say 60/40 for the mount building experiance. A friendly reminder to harden the horn mounting area. Well, enjoy your hobby nice to see interest in building your own trainer, verse ARF.
-Snuts-

If it was my plane and I was just starting out I wouldn't even put ailerons on it. As a beginner your main goal is to learn how to take off, land, and make some gentle turns. That plane will fly well with only 3 channels. Rudder and elevator on the right stick and throttle on the left.

I had that Eagle 2 with only 3 channels and mine would roll, spin, and fly inverted so easily. Having only 3 servos made my plane lighter and I didn't have to worry about 1 or 2 aileron servos go bad on me.

But, if he wants ailerons I'd use just the one servo in the middle. If he wants 2 I'd put them about 6 inches out from the side of the fusalage.

Good luck

big dan

Normally, setting up with two servos, one on each aileron, would be more for the torque for large ailerons or for the resistance presented to the aileron by the slipstream. Strength is necessary in that case. Also, you can get the benefit of a bit more control in the trim for each side with two servos. After all, once you set up the ailerons with one servo, using torque arms, what you get is what you get.

With that said, though, I must somewhat agree with the above post in that what is important for a learner is to learn to fly. Ailerons will help, but with a properly set up plane with dihedral, you can get the sedate response necessary with a trainer with rudder only.

I learned on a plane that had ailerons and liked the way it flew. I also flew with one that did not have ailerons (rudder only) and it was equally easy to fly, but the aileron equipped plane was more responsive.

Your choice of if you want ailerons or not, or if you want to use two ailerons or not. But I think for that plane, you will not gain a thing with two aileron servos.

CGr.

I say go with ailerons, but you really don't need two servos.

But there's no reason NOT to use two servos except for the extra work and expense involved.

That said, if you do decide to use two, do NOT put the servo in the middle of the aileron. Put it about 1/3 out from the inboard side. Nothing needs to be exact, close is close enough.

Mike, why a third out from the fuselage? I can think of a reason, but that's a best guess.. (leverage maybe?)

CGr.

It reduces any chance of flutter by creating a more difficult harmonic vibration. Ideally, it shouldn't even be exactly at 1/3, but slightly off.

Now that makes sense. Thanks for that.

CGr.

But if the plane was designed to have one servo mounted at the center of the wing, mounting two there isn't a problem.

Don't bother trying to add new locations outboard in the wing - just open up the existing servo hole at the wing center section, make sure you have hard points, and mount both servos next to each other. I have done this many times.

The Flutter issue is a different animal. Nothing you are doing is going to make it worse. (if it will even be encountered at all.) Now you have aileron redundancy and you can also play with flaperons, spoilerons, aileron differential and individual subtrims. Many will scream at the idea of using flaperons and spoilerons combined with strip ailerons, but I have been enjoying them on my trainers and sticks for as long as Dr. Rick has been stuck in the Land of the Lost.

Kurt

Well, that makes sense. I've never done two servos in the wing center.

If the OP really wants to go with two, one on each wing panel, well, make sure the servo "box" is secure and attached somehow to the spar and not the balsa ribs and that the servo box is constructed of something that will securely hold the servo in place. I use a piece of 1/4" x 1/4" along the front and rear of the box where the servo screws go.

I've also run a piece of 1/2" x 1/4" on both sides of the servo from the spar to the leading edge then made the "box" out of that by two pieces of that 1/4 x 1/4 between the 1/2 x 1/4 to sort of form the box using the servo as a template as to where to glue in the cross pieces.

It's easy enough to do, you just have to use your head and make sure you're not shore'ing up to a piece of 1/16" balsa or some such thing. And, have the "box" the same distance from the center on both sides (don't ask)...

CGr.

If it was me and I wanted ailerons on it I would use 1 servo in the middle and save $9.99 on not having to purchase a y-harness for that little "puddle jumper".

But if you want to go all the way out you might as well ad retracts, flaps, high torque digital servos, a bomb drop, a 12 channel 2.4 radio, and a nice O.S. 91 surpass with a brick in the back to balance it out. That would probably win some sort of award at the toledo rc show!

big dan

Just use two HS-81s or even bigger, two HS-225s. Plenty of torque for a dual aileron set-up for an Eagle 2. Don't use a Y-connector - plug each servo into the appropriate rx port (see manual for flaperons/spoilerons) and don't sweat it. It's all fun.

Kurt

Yeah, I did all sorts of wierd things on my Four Star 40 when experimenting.. back when. It was fun and taught me a lot. Got a lot of good info from the good folks here on RCU.

CGr.

There is no problem with putting the servos at the approx mid point. If there is then there are a lot of Hangar P-51 PTS's, Great Planes Escapades, Great Planes Ryan STA's, and Great Planes Super Skybolts that need to be re-engineered by the manufactures. All these have aileron servos at or near the aileron mid point. After flying some of them for years I have to say that they are all doing fine.

It's not a problem really, just a precautionary measure.

Not to mention the fact that by going less distance from center means shorter extensions.

I don't think anyone is arguing with you. Rather, either one will work, especially with a trainer or a stick.

Kurt

Oldvet,
Using Great planes in your example is a bad idea.
I think their engineering is some of the poorest around.
It is compunded by their poor instructions.
Good Luck,
KW_Counter

I crashed my trainer and it caused the rods from the ailerons [center servo] to bend and pull loose from the wing. It was easier to go to the two wing mounted servos than repair the original system. My plane did not have provisions for the servos in the center of the wings so I went to the furthest point of the wing sheeting about 1/4 of the wing and reinforced new servo mounts and it flew like a champ. Being a trainer I don't think the location of the servos is that critical especially since the original system worked from the end of the ailerons. If you choose to do this, make sure you use reinforcement under the skin.

Gary

shd3920

Did you friend decide on anything yet from the above posts?

big dan

So what manufacturer do you consider properly engineers their planes? Like I said the H9 P-51 PTS is about the mid point of the aileron. How about the Carl Goldberg Sukhoi 26? It's is within 1/2" of the mid point . The point is when I wrote it could be done at the mid point the OP was told "do NOT put the servo in the middle of the aileron." Well I disagreed with that and even the person posting it later clarified his statement. I cited 4 planes from 2 manufactures as examples, it did not seem necessary to cite more but if you dislike Great Planes as I say both H9 and Goldberg do it. Hopefully one of them is an acceptable example. If not so be it.