bad influence

Got A sweet deal on a .91 OS Fx and want to put it in a Thunder Tiger .60 trainer this plane is huge, 73 inch wingspan and built pretty sturdy. I know the .61 and .91 are the same weight and physical size. How can I back off on the HP. Reduce Carb? don't allow full throttle? I don't want to rip the front end off the plane.....

Nascar Restricter plate?? Ha Ha

Gringo Flyer

My Feedback: (18)

Now a days I think its actually rare to put a 60 sized engine on a 60 sized plane. Everyone puts 90 sized on 60 sized planes. I would never buy a 60 bc for the same weight you can use a 90. With that said on the trainer you will just have to have a bit of restraint. It is a lot of motor for a trainer, but it will be an awesome motor to have for other planes.

The OS 91 is a great motor for a lot of planes, you will have a lot of options after the trainer with this motor. From bipes, to acrobats, to even 2 meter pattern planes.

I would allow full throttle for break in and so that you can set the high end needle when you crank it up. Just dont fly it at full throttle a lot.

piper_chuck

My Feedback: (12)

Overpowering planes happens all the time. It's not normally necessary on a trainer, but since you've already got the engine, go for it. Choose a prop with a larger diameter (first number) and smaller pitch (second number). This will keep the speed down, but give you plenty of thrust. If the diameter creates a problem with ground clearance, go with a 3 blade prop that has a 1 inch smaller diameter. When you learn to fly, practice shallow climb outs using the wing rather than just having the prop pull the plane up. This will prepare you for flying planes with a lower power to weight ratio.

bubbagates

My Feedback: (32)

Piper said it best.

I use a 15X4 APC with that engine and it wiill fly a Funtana90 (90 size plane) just fine . Now remember the Funtana is quite a bit bigger and a little heavier than the trainer but that is one of the best 91 size engines going and are darn near bullet proof

The 15X4 will give you gobs of pull and keep the speed down. A 15X6 will be a good overall prop from most any plane with that engine

Ed_Moorman

My Feedback: (1)

These small case .91s are really chameleon engines. They can turn a normal, .91-size 14-6 prop or they can rev up a .61-size prop, like a 12-8 or a 13-6. Performance Specialties makes tuned mufflers for both sizes.

No matter what you do, your plane is going to be over powered. This should help you learn to use your left hand and get practice controlling power which is what you'll need for many planes. You will also find that a high drag trainer won't be all that fast compared to a lower drag sport plane.

You'll probably be able to take off and go around at half throttle or even less. Use caution popping the power to it on a panic go around as this much power can snap your plane over out of control quickly. This is where you bounce of maybe don't touch, but get the nose up and the airspeed down. If you hit full power, you can torque roll the plane over where your skill might not be enough to catch it before you crash.

If you do use a large prop, be aware that even though you have a lot of power, the large prop creates a lot of drag when you are throttled back. The plane may want to slow down quicker that you are used to. This is one are where an over powered plane can be difficult for those with less expceience. You might need to "play" the power 1 click at a time to fly a nice final approach.