Understanding servo sizes
 

I've been away for a few years and things have changed a lot. We used to purchase our servos by size and torque. I need to purchase some new ones and the terminology leaves me lost. When they refer to a 15g is this torque, weight or what. I need servos for a .15 sized plane and these were suggested.
Thanks for your help.

that's just an extra feature these days, most larger than micro sized servos show torque and speed (usually at 4.8, 6.0 and for HV 7.4 volts even :) )

15g refers to the servo's weight. a 15g servo weighs 15 grams.

Thanks for the reply. Hard to catch up.

Without a link to the specs for the servo it is impossible to tell. 15 grams could be the weight or it could be the torque.

its the weight

Can't go wrong with HS81 servos for .15 size aircraft. I use them extensively in .049 thru .19 size planes. They are plenty strong, fast, inexpensive, durable and they use standard Hitec servo arms. I'll bet I have 50 of them, about 1/2 purchased used online.

Thanks for your replies. They have been very helpful. I too have had excellent luck with HS servos.

I see a lot of servos sized by weight, 3.5g, 7g, 9g, 12g, they also give a torque rating 1.2kg-cm, 5kg-cm and so on. For a plane the size you are asking about, .15 glow power, you have tons of servo's to choose from. Analog, digital, plastic, korbonite, metal gear, plain, single bearing double bearing. You only limit is cost.

I have these in small foam planes to a 30 sized trainer, helicopters, gliders, glow and electric planes.

http://www.hobbypartz.com/9gexidimeges.html

I have a set of these, they are not a low cost budget servo, but not way over the top either. They have worked well for me in helicopters and gliders. Tough, fast, accurate servo.

http://www.hobbypeople.net/index.php...orq-servo.html

Servos have gone from only one to choose from, to so many you can go crazy trying to pick one.


Buzz.

Thanks for your input Buzz.
I started this RC thing back in the early 70's with a Kraft 2 channel brick. Been able to pretty much keep up with things until I took a breather a few years ago. Torque and dimensions were the main concerns with only a few option as you mentioned. Now it's like shopping for women's shoes, there is no end to it.
In the past when I needed help Heads Up RC has been a big help and their advice has been spot on. So I contacted them and they suggested this servo http://www.headsuphobby.com/Power-Up...ervo-H-240.htm
Hopefully they work out .
Thanks again for your advise.
Chris