oltma026

i have a plane with a 90" span an 11" chord, using an os 61 fx engine, won't change this, but could change the following

for my servos i am thinking that the elevator servo is going to be about 90 oz/in, ailerons at about 54 oz/in, and rudder at 45 oz/in
the elevator is going to be 3" by 30" and ailerons at 2.75" x 18" and rudder of 3.77" x 15".

i am not looking for high performance, all i want is to be able to take off and land. trying to carry as much payload as possible. can anybody give me an idea of whether or not these servos will be able to handle the loads. I used the servo torque calculator on coloradogliders.com but something doesn't seem right here.

ChrisMH

I think you could get away with standard (< 50 oz) servos for all your control surfaces. Since you say you're not looking for high performance your control surfaces won't need a great deal of deflection, meaning you can set up your servos for maximum leverage. Also, you won't be moving very fast, which means less load on the servos. You don't need a whole lot of torque.

Anyway, 90 oz/in on the elevator is definitely overkill. More torque won't hurt though, so if you feel like spending the cash...

Also, I'm by no means an expert, but I think your control surfaces may be a bit too big for this kind of airplane. I'd think ailerons/elevator around 2" wide, rudder 2 1/2" or so. I'm sure someone more knowlegeable will chime in. 'Course if the plane's already built, never mind

Chris

LANNYBOB

futaba's S3001 servo's will do or S3010 which are standard heavy duty high torque ball bearing. $25.00 each

rc-sport

My Feedback: (12)

Come on......tell us what your doing!!!! Sounds cool.

oltma026

me and some friends are all using the same engine, span, and chord and trying to determine who can carry the most weight in a payload bay. so i am trying to minimize weight as much as possible in order to carry more weight. all we have to do is take off, do a 360 and then land, ive never done a plane this large before so im not sure about the servo size necessary. thats what i am doing. i just want to make sure that my servos do the job.

thanks for any help

OldScaleGuy

My Feedback: (2)

The ole rule of thumb is 1 oz of servo torque per 1 square inch of control surface. It is a great starting point.

MinnFlyer

My Feedback: (4)

oltma, for what you are doing, cheap standard servos will work fine.

What Part of MN are you in?

Campy

My Feedback: (1)

Here is a link so that you determine exactly what you need for torque, then just select the servos.

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

FWIW - Balsa Products http://www.bphobbies.com/ has BlueBird servos. These are small, light weight (about 1/2 oz ) and go up to 57 oz of torque @4.8 volts. Regular servos weight about 1 oz each. I use them and they work fine - no problems at all. I would suggest the MG servos. I have found that the nylon gears don't hold up if they are pushed to the limit.