What surface do you put the strongest servo on when talking about 3D planes and 3D flying and this assumes that the elevators are split. I know this is somewhat open ended and it's intended that way

A few of us are having a pretty good debate on which surface whould have the strongest servo. Stronest means the most torque

Please feel free to give the reason(s) why. We would like to hear that as well

Simple. In general the order is..

1) RUDDER
Longest chord, large area, and minimal counter-balance, which adds up to the worst mechanical advantage against the air.

2) Aileron
About same area as rudder on many 3D planes but narrower chord, better leverage against the air than rudder.

3) Elevator
Small area, smaller chord than rudder and usually counterbalanced.


That's my $.02

I will accept no less than 1 seiko per surface on an F40.




Woops

definetely the rudder first, then ailerons, then elevators

I disagree. Rudder, then Elevator then ailerons. Regardless of how big the ailerons are, there is more strain on the elevators as they actually change the direction of the plane. The ailerons only rotate the plane, it does not change its direction. The overall weight of the airplane has little to no effect on how well the ailerons work. The elevtors can have most of the weight of the airframe on them at some times.

Onaedge:

You are right on. If your airplane will not move from a horizontal knife edge and then pull up into a hover you are either underpowered at the elevator or not flying a rcx planes .com. Now thats rudder authority. Oh yea, my Cap X wil also do that with a Jr 8611 on the rudder.

What is becoming clear is that none of us really knows


Let's just go with 8611's or 5955's all around to be safe

Now throw this into the mix. It appears that surfaces are decieving until calculated. This is on a 2 meter Extra Fun. Total aileron area is just a hair under one square foot.........each. Elevators are roughly 5/8 of a sq. ft. each and rudder is 3/4 sq. ft. So if going by area alone it would be ailerons, rudder, elevators, in order of torque required. Then as someone pointed out, shape or chord length. These particular ailerons and elevators have a 5-1/2 inch chord at the widest point, also the counter balance on the elevators is 7-1/2 at its widest point. Rudder is 8-1/2. Considering there are two each, ail and elv. compared to one rudder, I will stick with most force required for rudder with all else equal. Joe

I understand what you are saying about the surface size. You must take that into consideration. But you also must take into consideration what the surfaces do. I mentioned before about the elevators changing the direction of the plane and the ailerons do not. Look at it this way. How many G's are applied to the plane when you do a high speed aileron roll with 45Degrees of deflection. None, Zip, Zilch, NADA. Now, at that same speed pull full up elevator with 45 degrees of deflection. How many G's are applied. As many as 12 or more. This would take considerably more torque from the servo regardless of the size of the surface (unless you are talking huge ailerons and tiny, tiny elevators, which wont be the case in a 3-D plane). In fact, I would put more emphasis on the elevator than the rudder on most planes. In fact I cant name one plane that the rudder is as powerful as the elevator. I know many of you will disagree, and I will change my point of view if I'm proven otherwise. But since we are talking about split elevators and to prevent a war, I still say Rudder, then Elevator, then Ailerons.

I considered one rudder = one servo at app. 1/4 more area than both elevator halves combined with one servo each. On its side, in knife edge, the rudder is now acting as elevator, one servo is working more area, as opposed to two doing the same control on elevator. Also, on its side, there is no benefit of wing lift, so is it working harder than elevator, on its side?
I hear you on the ailerons, although larger in area, its spread out the width of the wing and as you stated, doesn't change the attitude of the model or carry as much extended force. Interesting. Joe

i always put the largest servo on the rudder

but if they all are high speed/tork i put them on everthing but throttle


38

Without a doubt, rudder is the largest piece on most 3D planes.

Also, it's most likely a tail dragger w/ long tail moment, which means a lot of load goes to rudder during landing, taxing, and evening just starting the engine. For this reason, I use metal gear on rudder for its structural strength on planes heavier than 7 lb.

If 1 servo drives 2 elevator pieces, then I would put my a strong servo there too. It's better to get more strong servos than to end up with 1 less plane.

There seems no doubt that the rudder requires the largest force, but I always put my best servo(s) on the elevator. If I were to lose control of any surface, I would rather keep the elevator...

Amen... I can get a plane down without a rudder and on one aileron, but lose the elevators and it's all done...

In order of most torque / speed, I vote for rudder, elevators, ailerons...

Having said that, with the choice of servos available today, I usually use Hitec 5955's on all surfaces on 30% and larger airframes... Close in price to the other top of the line servos, programmable, no gear slop after 75 flights and strong as hell...

I agree with you. First Rudder, then Elevator, then ailerons. On standard 3d planes, we use 2 servos for ailerons, instead of 1 to rudder and 1 to elevator. Thats a good reason to put rudder and elevator on top of the list

Don't forget about leverage. The elevator and rudder have leverage working for them. It is easier for them to change the direction around the wing because of it. The rudder on 3D is usually a lot longer in cord than the elevator also, so that also causes more pressure at the horn. The rudder also is working against the fusalage side area as well. These would require more torque. The ailerons don't have the leverage so they are working against the load of the wing. On my full size biplane, the elevator is very light (can fly with 2 fingers on the stick), the rudder is quite heavy (worked with the feet though), and the ailerons considerable heavier than the elevator. My 2 cents worth would be 1-rudder, 2-ailerons and 3-elevator.