control surface flutter
 

I was wondering if using two of my hitec 605 servos for rudder and elevator is overkill. They are hi torque 77oz. The plane is an uproar60 with a webra 80 two stroke. I was also planning on using two standard ball bearing servos for ailerons. This is my first funfly model and i am worried about flutter with the larger control surfaces.

control surface flutter
 

Make sure there is no slop in the linkages, and don't try to fly it too fast and you shouldn't have any problem.

--Paul

control surface flutter
 

speed is your enemy. i've heard lots of horror stories regarding uproars and dazzlers ripping apart because of too much speed. make sure you prop it for thrust, not speed! if you get flutter you are flying too fast for that plane!

Fun flies Bzzzzzzzzzzzzzz
 

Funflys were not designed for Speed, large surfaces and speed dont mix, and with that Webra 80 you are going to have alot of speed, so selecting the right prop will be important, and throttle management.
Don't fly straight and fast, use the throttle as needed for manuevers. Throttle back for level flight. Good luck. Daz...

control surface flutter
 

A friend of mine had his Dazzler shed its wing covering twice, one time the horizontal stabilizer broke. 3 or 4 times this happend to the bottom of the wing. Finally while flying at a demonstration during our high schools spring week, the top covering flew off, then the rest of the plane ripped itself apart.

It was really spectacular. Several of the guys in the AMA club we belong to were telling him over and over that someday it would do that. Some of us were practically placing bets.

--Paul

control surface flutter
 

Thanks for all the advice guys. I was planning on using a 13/6 prop but now a 14/4 or 5 sounds better for speed control.By the way, this uproar is going on floats and hopefully clean up at some of the float fly events we have on the B.C. coast this summer.

control surface flutter
 

Having been bitten a time or two too often by flutter, I use mass balancers on the ailerons and elevators of everything I build, and have have little trouble since. Addition of mass balancers can make even competition fun-fly models virtually flutter-proof, when without balancers, they would flutter badly at anything over 30 MPH or so. I have flown such models at speeds in excess of 100 MPH, with aileron chords over 4", without flutter, thanks to mass balancers with the right balance moment.

control surface flutter
 

Re servo torque required - Multiplex has an excellent program available at: http://multiplexrc.com/calcservo.htm

The program works well, but has a glitch - It tends to overestimate servo torque required, since it seems to assume that the servo output arm moves through the same angle as the control surface. This error can easily be corrected by simply multiplying the result that the program spits out by the ratio of the control surface deflection to servo arm deflection.

control surface flutter
 

What is a "mass balancer"? Are you talking about the counterbalance used on some control surfaces? I'm talking about the part that extends forward fromt he hinge line.

control surface flutter
 

Yes, Paul - it is just that. I usually incorporate them into the tip portion of the control surface, but have made many others from streamlined coffee sticks with streamlined lead weights epoxied on. The stick faces ahead of the hinge line at an angle that is just sufficient for the arm to clear the wing or stab at full deflection. This type is easy to rig up for a quick test; later you can do a more sanitary job. It is important not to overdo the weight - too little is much better than too much, since excess balancer weight can excite higher harmonics that can be very destructive.