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Old Mar 21, 2004, 08:14 PM
Gravity is a harsh mistress.
Tim Wolff's Avatar
United States, MI, Temperance
Joined Sep 2002
6,535 Posts
Alieron actuator pair connected in series or parallel?

I'm adding alierons to my No-Cal Corsair. I've stuck a 50 Ohm Actuator in each wing. Should they be connected in series or parallel? They will be connected to a JMP Combo RX. It is actually already wired parallel. All plug-in allowing the reversing of either or both actuators. Is 25 Ohms too small a load for the JMP RX?

TIA

Edit:
DOH! Apply Ohms law.
I=V/R
I=3.7v/24.5 Ohms
I=0.151 Amps
I=~151 mA

Well below the 400 mA rating of the JMP actuator outputs..

Please jump in if I'm mistaken.
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Last edited by tiberius; Mar 21, 2004 at 08:32 PM.
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Old Mar 21, 2004, 08:57 PM
Team 30 Micro EDF
Mike Taylor's Avatar
Camarillo, California
Joined Apr 2002
4,516 Posts
I've used two coils for ailerons, and I asked Clarence Hurd (RFFS designer) about it - he said put them in parallel. It has worked OK. If you do this, please add magnetic centering to each coil, otherwise aileron flutter is almost assured. Without centering, they flap like a flag.

A much better approach, where possible, is to drive both ailerons off the same actuator. The weight of one offsets the other, and each helps dampen flutter in the other. Magnetic centering from the other actuator helps smooth out the controls. Here's a picture showing ganged ailerons. This little plane is 14" ws, 28 grams, and capable of very high speed without flutter problems.

The control rods are .030" CF rod in 1/16" K&S aluminum tubing, and are virtually friction free. Adjusting the angle the horns are attached can build in aileron differential. When the horn and actuator are above the wing, as shown, the horn slants forward 15* when the surfaces are centered. This helps prevent adverse yaw.
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Last edited by Mike Taylor; Mar 21, 2004 at 09:15 PM.
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Old Mar 21, 2004, 09:04 PM
Team 30 Micro EDF
Mike Taylor's Avatar
Camarillo, California
Joined Apr 2002
4,516 Posts
If you really need to mount the ailerons with individual actuators, they need an additional magnet to help center the surfaces.

The weight of the surface is a problem since the surface droops. As the plane comes up to speed, the ailerons begin to fly, but at low speeds they tend to droop, and at speeds inbetween, one will start to fly before the other. This makes control somewhat tricky.

If you want to do it, here is a picture of a self centering magnet added to a surface mounted aileron. The magnet is just below the rooster's beard, and is a 1/8" x 1/16" rare earth magnet. This flew acceptably, but no where near as well as the same models with coupled ailerons. I don not recommend this type of installation if you can avoid it.
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Last edited by Mike Taylor; Mar 21, 2004 at 09:07 PM.
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Old Mar 21, 2004, 09:08 PM
Gravity is a harsh mistress.
Tim Wolff's Avatar
United States, MI, Temperance
Joined Sep 2002
6,535 Posts
I couldn't come up with any way to use a single actuator due to the Corsair's gull wing. I was planning to use a few lenghts of guitar string to provide centering. The last time I tried to add magnetic centering to a bird-mounted actuator I made a mess and ruined a coil. I really wanted to use remote actuators, but I don't have any available housings at the moment.

Thanks for the tips.
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Old Mar 21, 2004, 09:25 PM
Team 30 Micro EDF
Mike Taylor's Avatar
Camarillo, California
Joined Apr 2002
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Oh, Tiberius, I didn't even look at who posted. Sorry for the tutorial. DWE has some very easy to use coil adapter kits to make your surface mounted units into remotes. There made by Gary Huthison, and they are the easiest to put together, and they are like 2.50. A Bob Selman standard size is really needed for two surfaces.

The Corsair is a special case where two are better than one. Experiment with a centering magnet. I've had luck with the 1/8" x 1/16" mounted 1/8 or so outside the coil. Two 1/16" x 1/32", one on either side of the coil also works pretty good. I had flutter problems that would stop a plane dead and drop it straight down. This flutter went away with magnetic centering. Do be careful not to drop the magnet against the coil of an assembled actuator; that will cut the wire.
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Old Mar 21, 2004, 09:30 PM
Team 30 Micro EDF
Mike Taylor's Avatar
Camarillo, California
Joined Apr 2002
4,516 Posts
BTW, magnetic centering better (IMHO) because it is at maximum at center where you want the dampening, and at minimum at full deflection. Wire, on the other hand, is exerting minimum force at center where you need help the most, and maximum at max deflection where you can afford it least.
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Old Mar 22, 2004, 07:16 AM
Gravity is a harsh mistress.
Tim Wolff's Avatar
United States, MI, Temperance
Joined Sep 2002
6,535 Posts
"Two 1/16" x 1/32", one on either side of the coil also works pretty good."

That sounds doable. I tried a 1/16" x1/32" on only one side of the coil when I had problems. It just pulled the actuator magnent to one side of the coil. I'll have to do some testing and marking of the magnent orientation before I attempt to put it all together.

I'm going to get a set of the Huthison housings at the Toledo Show if Dan has them with him. Prob. a bunch of other stuff too.

Good point about the centering wire and the forces compared to the magnetic centering.
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