Multiple servos for elevator?
 

Using multiple servos for ailerons and elevators for the first time. Have a servo for each elevator half and one for each aileron (Bipe so there are four).

Am using a futaba 6 channel radio and am a bit confused on the wiring and reversing. I have my left ailerons on ch 6 and rights on ch 1. Seem to be working fine.

Where I am confused is the two seperate elevators. My elevator servos are turning the same dierction on opposite sides of the fuse. I have no room to have the control arms reversed, ie one pointed up and one pointed down (the servos are right next to the horiz stab). How is this reversal addressed?

Thanks!

Eric

RE: Multiple servos for elevator?
 

On the elevators, you have to mix them in the radio. If you are using a Y connnection, you have to have the arms on the opposite side or reverse one of the servos. Otherwise, plug them into like ch 2 and 5 and reverse one of the channels to make them work the same.

RE: Multiple servos for elevator?
 

I had the same problem with my U-CAN-Do .46. When I bough my HS-425 BB servos from Servo City (http://www.servocity.com/) it was only $8.00 to have them reverse the servo inside. That was cheaper and more safer than buying a reversing Y-wire harness.

RE: Multiple servos for elevator?
 

The arms have to be on the same side of the servos for elevators using aft side mounted servos. The geometry to the horn on the surface is different for each side if the arms are pointing oppositely. There will be a differential effect between the elevator halves.
With the servos mounted in the sides of the fuselage (rotation axis horizontal). one must have the electronics reversed.
If the servos can be mounted normally (rotation axis upright) in the cabin, then the pushrods can be attached to the opposite sides of each servo and the motion at the elevators won't have the differential.

RE: Multiple servos for elevator?
 

Uh, Paul... Wouldn't that make them go in opposite directions?

GrumpE - Easy fix, just buy a reversing "Y" cord. It will reverse one servo and leave the other as is.

RE: Multiple servos for elevator?
 

Just checked my LHS. No reversing Y harness in stock. Ran a search here and found a thread (should have done it first). MinnFlyer, what are your thoughts on reversing my own servos inside. According to the Hitec link in said thread I reverse two leads to the pot and two to the motor. Seems pretty straight forward.


Or I could order another one from Servo city and have them do it. Of course I could have a reversing Y shipped as fast as buying a servo for less money.

Hmmmmm

Thanks Guys!

Eric

RE: Multiple servos for elevator?
 

.??
Which "that"?
The side-mount description or the normal description?

RE: Multiple servos for elevator?
 

A suggestion on the instalation of your 2 elevator servos. When installing the clevises in the two elevator halves, etc. Make sure everything is exactly the same on both sides. This might seem like common sense but I didnt even think about it on one of my planes and the clevises are not exactly the same on both sides. Now the extreme end of the throws doesnt equal exactly on both sides and I have to go back and fix it because the plane rolls slightly with full elevator.

Maybe common sense, but it doesnt hurt to keep that in mind.

I used the servo reversor, its a little expensive but easy to work with.

RE: Multiple servos for elevator?
 

They covered it all:

easy--servo arms on opposite sides
easy but $$--reverser
not so easy--reverse the wiring inside servo

I have the same issue with my Ryan. I do have the room to have the arms on opposite sides.

Sorry I have nothing further to offer.

RE: Multiple servos for elevator?
 

So, I am hearing you can't use ch 2 and 5 and let the radio take care of the problem? Why?

Thats what I do in all mine. Then I can use the transmitter to make sure the throws are exactly the same.

RE: Multiple servos for elevator?
 

A couple of additional thoughts.

It depends on the Tx. If the radio has mixes available, that is the easiest way to accomplish the task IF both channels used have trim available. If trim is not available on both, one side will trim and the other will not. Not an acceptable solution.

The second is, once a way to reverse the servo is determined, another issue pops up. All servos are not created equal. You will need a matched set that moves at the same speed and distance. If you are lucky and start with 4 or 5 servos, you can usually find two that are matched. The alternative is using unmatched servos, where one will move fruther or faster than the other, which results in some strange effects on the aircraft. That is why things like programable servos and Matchboxes are made.

If these are standard or larger servos, and you have the soldering skills, reversing the wiring is not difficult. On some servos it is very difficult because of the physical layout inside. Look inside before you leap. Micro servos are always a pain to rewire.

RE: Multiple servos for elevator?
 

Not sure.

First time I have tackled multiple servos. Using a Futaba 6XA system with a Hitec 8 channel Rx. Have available mixes etc but have never used them.

Spliting ailerons to 1 and 6. Using two batts, in Ch 7 and Ch 8. I have two NiMH packs availble so am not buying a bigger one.

Do not know if I can use 5 and then "link/mix" it to 2. Working and do not have the manual handy to see.

This sounds like a good solution if it will work. Anyone know off hand?

If not will do some reading tonight when I can sit down with the, e gad, DIRECTIONS.:D

Eric

RE: Multiple servos for elevator?
 

That might work. A simular construction can be made with my HiTec Eclipse transmitter. One downside though is that the elevator trim may not work for the 'slave' channel. This would mean that you need to adjust the trim of one of your servo halves (the 'slave') manually every time you want to adjust.

Jock

RE: Multiple servos for elevator?
 

Go to http://www.futaba-rc.com/manuals/notes-6x.html to download the manual

RE: Multiple servos for elevator?
 

Here's several of the possible arrangements.
The first is the common one, as both servos are usually back-to-back in the rear fuselage. The arm pointing up has less up movement at the elevator, as it moves down on its motion around the servo output axis, while the down pointing arm moves up. The difference is small but it is there.
This also occurs with the second arrangement.
The servo can be reversed at the transmitter, requiring 2 channels and mixing, or one can be internally reversed, and a y-harness used on a single channel, no mixing needed.

RE: Multiple servos for elevator?
 

For your Futaba 6XA computer radio, I don't think you have the option to mix channels 2 & 5. On the new 7 and 9CAP you do. Your best bet would be the reversing Y. They work and the better ones allow other adjustment as well. Just make sure your full travel throw is exactly the same on both sides, as this can cause some real unhappy situations.

RE: Multiple servos for elevator?
 

Suggestion I got (in my STA-M post) was rather than changing ie-rewiring INSIDE the servo, just snip and exchange the two power wires outside the servo. I think I'm MUCH better at snip and solder only wire rather than try to unsolder it from the pot and resolder it.

RE: Multiple servos for elevator?
 

If the 2 power wires outside the servo are reversed, the circuitry INSIDE the servo will go up in a tiny puff of smoke.

YOU MUST reverse both the connections to the servo motor and the outside 2 wires on the pot to reverse the servo.



FACT: All tiny electronic components come filled with magic smoke from the factory.

This magic smoke is needed for proper operation.

Let some or all of it out, and the circuit stops working.