I recently picked up a Great Planes Ultimate kit. I really like flying bipes and I'm looking forward to having a 40 size that will fit in my truck assembled. I do have a question about the ailerons for anybody that already has this plane flying. Will a single aileron servo be enough for all 4 ailerons?? or is there a mod to put in two servos?? I have flown a hog bipe (aileron servo on each wing) and a DP Ultimate (servo for each aileron), and I want to make sure that one servo (as per the instructions) will handle this plane. standard servo?? or a high output servo??

thanks in advance for any advice

Ken:

A single aileron servo will work on almost any airplane in the 0.40-0.60 size range, but usually two are used. Couple reasons. There is the possilility of overloading a single with aerodynamic forces, a biplane seldom is fast enough to have a problem here. Two servos just seem to flip the flaps faster. More precise control from having less linkage pivots. And for the same reason less tendency to flutter.

Comes down to you - add the weight and expense, go cheap and adequste.

Bill.

On your plane a standard single servo will work fine unless you want to do some programing

I was planning on going with a single servo like the plans say to. Unless I get feedback here saying 2 are better. I've been flying long enough (and had enough planes) to know that sometimes it's better to listen to other people who have had the same plane. That's why I took the time to ask here.

Ken:

Just went back and looked at your iniitial post again. Four ailerons. One servo in each bottom wing is strongly recommended. Consider all the linkage pionts operating them with a single servo. Best would be four minis, on the order of the Hitec HS225BB servos. But two will do. Definitely not a single servo operating all four ailerons.

Bill.

Sorry Bill, I don't mean to contradict you, but my dad and I each have one of these and we are both using a single standard servo to control all four ailerons.

Between us we have over 100 hrs on these planes with no problems.

I have a GP ultimate that has many flights on it and it is built just like the plans. One standard BB servo operates all 4 ailerons. I have never had any problems with this setup. On high rates this plane has a very fast roll rate and will do great aerobatics. Just make sure that you use the recommended control throws. It dosen't need more throw than the recommended amount.

Rick

Minn:

If it works what can I say? I just think about all those linkage connestions, each with its little bit of slop...

Some people use a single servo to operate both throttles on a twin. I don't like that either, but on the really small planes I also use a single throttle servo. No room for two.

Bill.

Haven't flown the Ultimate, but have read reports of flutter problems with the single servo. With the weight of the aileron connector link on the aileron trailing edge, any looseness or flexibility can induce flutter. If you can produce the torque rod single servo installation without flex or play, a single servo is probably strong enough and will work OK. If it feels sloppy, though, I'd do the modification.

Several posts regarding flutter problems have pointed to the kit's small connector hardware as the culpret. But you are all correct to say any slot at any point can cause flutter and should be eliminated. Several have said to convert the kits aileron connection hardware to 4-40 heavy duty to control flutter.

I flew my GP ultimate for about 3 hours of filght time today and have had no problems. I have about 125 flights on this plane since I got it and it was flown by two other people before I got it so who knows how many flights it has on it. I have the single servo in my plane and it is fine. There is no slop or play in the linkage and the ailerons do not flutter at all! If I were building a kit of this plane I would use 2 aileron servo's. It would just be a better way to do it. If you have a computer radio it will also give you more setup options. With the one servo setup there is alot of places that bad things can happen. I personaly have not had any problems with mine but I would use the 2 servo setup if I was building one from a kit.

Rick