spitflier

My Feedback: (2)

Is there a chart or rule of thumb as to what servos to use as far as torque & speed ect I have a World models Giant scale spitfire and the instruction sheet SUCKS good thing this isn't my first ARF I but there isn't any mention of servos For instance what do I need a high torque servos for, flaps, airlerons rudder elevator How high is high enough, 125 in-oz? Can I use standard size in a non aerobatic plane? Thanks for the help

mrbigg

My Feedback: (21)

Hitec 645MG servos would work good or ones with about the same torque.

spitflier

My Feedback: (2)

Thanks but I'm looking for the way to figure it out for myself not an answer per say you say a 645 servo but is that for all surfaces?

Hammbone

My Feedback: (309)

I'm sure someone could come up with some highly complicated mathmatical formulas that would take into account the size of the control surface and the spped of the plane. You'd have to also figure in your linkage geometry, etc. etc., but it still wouldn't be completely accurate and we just don't have any such formula that we use.
Manufacturers usually recommend a minimum torque rating for servos that will be used on their planes. If you're plane doesn't come with recommendations, then look at what other similar sized planes are recommending. I'm not familiar with the World Models Giant Scale Spitfire.

Jim

spitflier

My Feedback: (2)

Thanks Jim
I can't find the specs for a similar plane. Mine has an 80 in wingspan and should weigh about 15 lbs
Someone out there must have a clue how to size a servo. Guessing or over sizing just because we can, doesn't make sense in a hobby that is so steeped in calculations
I know that ailerons and rudder need higher torque but how about the split flaps any reason I can't used a standard servo (of which I have plenty of) I would like to know for real not just "this should work" don't know if the type of plane matters It's not an aerobatic plane but I want it to be able to do whatever it's capable of

Flying freak

Look up the manual for the top flite p-51 (84 inch wingspan)

aaxiss

Splitflier: alot of this hobby is based on A LOT of trial and error and alot of the errors are in the mfg instructions LOL. I have a 94" span yak 54 an the instructions recommend ( Strong plastic servo arms ) . Heck, If I followed that recommendation I would probably lose half those arms on my first snap. I realize you want a formula to figure it out. I was no math wiz bu I a guessing there is a bit of algebra in that formula. I find it easy to just ask alot of questions and just go with it . If someome were to say x srvo would work but z servo is better than 8 people follow up all praising the virtues of z servo I'm gonna probably go with z.


As far as the high torque servos go.... Whats the heaviest plane you have ever flown and how fast did it go?. Just for an example one of the local guys at my field is flying a giant zero at well over 100 mph . At those types of speeds on a 20lb + plane there has to be an unsane amound of force acting on the elevators when he rolls that thing over into a banked turn at those kinds of speeds.

If yu ask enough questions you make get the correc answer sooner ao later or you can use the answers you get to make an informed judgment. Or you can do like I did and just buy the strongest / fastest servo knowing it will go into a bigger plane sometime in the future. IMO , only thing i would use standards on is flaps