How much torque do you need?

How do you know if you've got enough torque in the servos you're using? I can see one (very complex) way of doing it would be to have a (recording) ammeter in-line with each servo and see how much power they draw as you put the plane through it's paces. Other than that, or the plane falling out of the sky, how can you tell if your servos are struggling?

Thanks, Steve

Reply to
Steve
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There are a couple of servo torque calculators out there. Do a google search for them. They will give you an idea of how much servo you need. They can be a little complicated to use. In general, most people probably use more servo than is really required.

John VB

Reply to
JJVB

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

Here is a link to a servo torque calculator.

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Reply to
Ted Campanelli

As suggested do a search for some torque calculators. They are rather basic but will give you a good idea.

One I tried required control surface width and chord, max deflection angle, and max speed. From that I assured myself that my servo choice was OK. Input the max deflection and speed higher than what you realistically expect, it will give you a good safety margin particularly if you up the throws etc later on.

Reply to
The Raven

I tried that with the one provided earlier and came up with some really low numbers (along the lines of 10-13 oz-in for the elevator and

4-8 oz-in for the rudder on my 40 size trainer). I am led to believe that either the calculator is a bit off or we way overpower our servos (along with our engines....).

What would the symptoms of an underpowered servo be in flight?

Steve

Reply to
Steve

Quick, normal reaction static, but slow reaction in flight. We all tend to overpower anything we can get our hands on .......

Reply to
Eye Indo

I have never had too powerful a servo crash a plane. I have had underpowered servos come perilously close to crashing a plane. Watts are cheap. Planes are not.

Ed Cregger

Reply to
Ed Cregger

At the price of our Hurricane servos, why not go HIGH torque? Check 'em out at

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Our standard size 92oz servo is only $15 with DIGITAL 152 and 191oz metal gear servos going for only $40 and $45. We have all the spare parts too. Gears, cases, arms, etc.

Reply to
Jim Slaughter

I just purchase the highest torque capacity units for what my money can buy. Never think of IF I really need it. What I want .... that is another story ....

Reply to
Eye Indo

When the surface "blows back" at speed, you don't have enough servo attached to it. In general, a .40 size trainer doesn't have very large surfaces or very much deflection, so assuming you set the servo up to move the surface the required amount WITHOUT limiting the servo travel, you get a mechanical advantage.

On "fun-fly" types with huge control surfaces and 45 degree deflections, the servo requirements go up REAL fast as the speed rises.

Aileron blowback on one of these makes your heart rate rise REAL fast.

Reply to
Bob Cowell

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