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How big before multiple servos on a control?

Bigbird

Bigbird

30cc
One of the reasons guys are running such crazy powerful servos is the total throw they ask of them. Using 2" long servo arms throwing the surface 65/70 degrees takes a lot of power. Then throw in there the WOT crazy stick bending flying style and you can be asking for more servo power. ARF's make it easy with min recommendations. Good rule of thumb is to always remember those are min recommendations. Sticking more powerful servos in will not hurt anything. Just make sure they fit before buying. That and with tail mounted servos weight should be a huge concern. Really easy to end up with a tail heavy airplane from a poor servo choice.
 
Snapasaurus

Snapasaurus

50cc
Whatever was said above and before is true, my batteries once ended up in the tail of my plane, many times I put all my batteries in the tail, wasn't trying to balance the plane but figured it wouldn't hurt. In my next project I plan to install a smaller 50oz smoke tank.
 
SleepyC

SleepyC

150cc
Snapasaurus;1403 wrote: Whatever was said above and before is true, my batteries once ended up in the tail of my plane, many times I put all my batteries in the tail, wasn't trying to balance the plane but figured it wouldn't hurt. In my next project I plan to install a smaller 50oz smoke tank��.
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200oz smoke.. nothing less.



Is there a world record for torque rolling with smoke on? SNAP!!! LET's CALL Guinness Book Of Records. Get a plane ready! 45 min of smoke and torquin!
 
Snapasaurus

Snapasaurus

50cc
SleepyC;1407 wrote: 200oz smoke.. nothing less.



Is there a world record for torque rolling with smoke on? SNAP!!! LET's CALL Guinness Book Of Records. Get a plane ready! 45 min of smoke and torquin!
Click to expand...
You got it sleepy, we can do that and with a 50% or bigger airplane .
 
Mikeq

Mikeq

150cc
Bartman;532 wrote: A big question I've always had is how big can you go before you need multiple servos on your control surfaces?



I think it's pretty safe to say that 30 to 40CC planes (about 70 to 80" wingspans) are going to be fine with a single, metal gear servo on each control surface including the rudder. Keeping in mind that 3D flying requires more servo power than Sport/Scale flying (because of the extreme control throws), what is a reasonable rule of thumb for when it's time to put two servos together?



I'm a sport flying kind of guy so I've been able to get away with single servo control surfaces on a plane up to 70cc but I also understand that you hardcore 3D guys probably couldn't count on a plane to survive that long if you did.



Adding a quick explanation to this first post, control surfaces become increasingly harder for the servo to move as things like airspeed, surface size, and the amount of deflection go up. It's easy to move a small surface, on a slow plane, a small amount. A big surface though that's on a fast plane will need a ton of power behind it for an abrupt maneuver that requires a lot of surface deflection. It all has to do with the air pressure that is acting on the control surface as it's being deflected from its neutral position up or down into the airflow around it.



So, for a first time Giant flyer, what's a safe and reliable rule of thumb?



Bart
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Pilot and others makes it where servo count is optional...they will have 3 aileron cutouts on a 35% airframe for you to either go one center or two inboard and outboard on their ARFs. Likewise on my Pilot 37.5 Yak I could do 3 aileron and 2 elevator or 2 aileron and 1 elevator...I emailed Tony at Pilot and of coarse he recommended 3 and 2 but I also talked with several people including IMAC guys who recommended 2 aileron and 1 elevator which I did with JR 8711s and I've been flying over a year no problems.... we do have a club member that uses one high torque aileron servo on his 35% Pilot 300 and the flutter on the aileron is very noticeable when he starts the plane...you can tell the aileron is bowing and oscillating from the center out while the plane's engine is warming up which that alone would make me go with 2 servos instead of one regardless of the torque.



Edit / Delete Ed
 
Erikv79

Erikv79

30cc
Snap is a force of nature! After five days at Nall and seeing very few women, let alone any close to my age, this man brought them out of nowhere! Like magic!
 
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