Hi, im a new builder and have started work on a sig 1/6 scale clipped wing cub. Wingspan is 56" and im not sure which servos to use. The plan suggests installing a single servo in the fuselage to drive the ailerons via push rods and bellcranks however i'm reluctant to go down this route. I plan to embed one hitec hs-55 servo in each wing to eliminate control
slop but im unsure if the hs-55 has the muscle to do the job. In short, is there a method to calculate how much torque a servo should provide for a particular application? I picked the
hs-55 for the following reasons:

1. feather light
2. Wont put too much strain on the wing
3. Fits inside the wing with the control horn sticking out
4. No control slop

Any help welcome

eeipshy,
I would go with a standard size servo on this plane, the hs-55's are just a bit weak as those are used for park flyers most of the time, if your looking for cheap go with these,
http://www2.towerhobbies.com/cgi-bin...?&I=LXN586&P=0

If it were me I would go with these if I was using Hitec, you can never have to much servo.
http://www2.towerhobbies.com/cgi-bin...?&I=LXUZ87&P=0

These would also be good choices, if your a Futaba person,
http://www2.towerhobbies.com/cgi-bin...?&I=LXH296&P=0
http://www2.towerhobbies.com/cgi-bin...?&I=LXFKZ8&P=0

Don't worry about putting stress on the wing, it's the servo that has to deal with the stress.
Most all servos will fit in the wing.
This plane can handle the extra weight.
That wing will rip the gears out of that 55.

I looked at this plane on the web site, and it could be possible to go with HS-81 w/metal gears if your intent on sticking with mini servos. the plane is smaller than I thought. I would probably be in the 30-50 oz in of torque for that plane, sorry I don't do metric.

Checked the specs on the hs-55 and its output torque is 15oz.in, unfortunately i already bought the servos with resin gears so im in a bit of a bind as the budget is tight.
When the model is finished the last thing i want is to crash because the servo gears fail in mid flight.

Saw someone else using the hs-55, see image

Here is a link to a calculator. It will tell you how many oz of torque you need.

http://www.csd.net/~cgadd/eflight/calcs_servo.htm

If you want small, powerful servos, check out BlueBird servos (up to 57 oz @4.8 volts).
http://www.bphobbies.com

I use the Bluebird servos all the time. The only negative is you want the metal gear servos. The nylon gears don't hold up, especially if pushed.

try these servos i used them in my cap232 alerons. http://www.servocity.com/html/hs-81_micro.html