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Coreless servo for dual servo elevator

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Old 02-16-2005, 10:08 AM
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dannost
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Default Coreless servo for dual servo elevator

I am building a P-38 with an elevator servo in each boom. I want to use a servo that moves freely so that if it
fails the other servo will not be working against it. I'm trying to keep the weight down if possible. Does anyone have
suggestions? I don't think I need a tremendous amount of torque, since it is a 1/8 scale, and I'm not going to try 3D
moves and there will be 2 of them.
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Old 02-16-2005, 11:09 AM
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Default RE: Coreless servo for dual servo elevator

It would be simpler just to split the elevator into two parts. Then one servo will not interfere with the other.
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Old 02-16-2005, 11:37 AM
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Default RE: Coreless servo for dual servo elevator

Typically when a servo fails it either jams or it hardovers it does not just "let go". Either of these would cause you to lose your elevator regardless if you had another servo installed.

Not sure how you'de split a P-38 Elevator...

If you need to use two servos, align them like we align multi-servo ailerons using the programmer or matchbox and don't worry about it.. use a good cored motor digital to keep the cost down and you'll be fine.

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Old 02-16-2005, 11:42 AM
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Default RE: Coreless servo for dual servo elevator

JR 3121 would be a good choice, although not that cheap.
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Old 02-16-2005, 12:51 PM
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Default RE: Coreless servo for dual servo elevator

I have been very tempted to split the elevator. This would allow me to use any servo I wanted and avoid any problems if one of them did go out.
I',m just hesitant to split it as this is not scale.

To use a digital would I have to buy a programmer in order to sync them?
If I use a match box, do you have to use digital servos?
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Old 02-16-2005, 02:56 PM
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Default RE: Coreless servo for dual servo elevator

If you wanted to use the Hitec programmer, yes they have to be digitals as you are programming the servo itself. The cored digitals are nice servos and not very expensive.

If you use a matchbox or the Smart Fly Equalizer you will not need digital servos as the programming is done inside it instead of the servo.

If you have analog servos already and want to match them, the best option is the Smart Fly Equalizer.
I think the matchbox works the same way, I have only used both of these on digital servos so I would double-check to make sure that my statement is correct before you buy one!

Since pulse width is pulse width though , I would think the matchbox and equalizer will work with ANY servo.

I wouldn't cut the elevator on that bird... it just wouldn't be right!!


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Old 02-16-2005, 03:55 PM
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Default RE: Coreless servo for dual servo elevator

I'm thinking of going the Matchbox route. The matchbox can't weigh enough to worry about. The one other option of course is to use
a single servo in just one boom. I can easily get a servo with enough torque. It's just a matter of whether the elevator is stiff enough
across the length to be driven from just one side.

BTW, who makes the Smart Fly Equalizer? I have not heard of it. Is it comparable to the Matchbox?

Thanks
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Old 02-18-2005, 11:56 AM
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Default RE: Coreless servo for dual servo elevator

I think you are trying to fix a problem where there isn't one. If your elevator is not stiff enough then two standard servos will not fight each other as the flex of the elevator will take care of it. If they do fight each other then just take one of the servos out.- The elevator is stiff enough.
BTW a matching device is rarely needed with standard servos. The dead band is usually about 1 degree. That takes care of it unless one of the servos is way out on the end point.
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