Listen to Boomstriker.

The TT engines do wonderfully in airplanes. Their record in helicopters is, shall we say, less than sterling. As Boomstriker said, its all in the carburetor.

The OS 32 SX is THE engine for 30-class helicopters; it is the benchmark by which all others are judged. The trend these days is for ever more power, and since the TT 36 is definitely more powerful, you will get lots of recommendations for it. But if you do an extensive search, you find more posts regarding trouble with this engine than ANY other. Things don't seem to be a lot better with the TT 39; I still see some trouble posts about it.

I'll echo Boomstriker; aside from the cost difference of a new 32 SX and rigging your plank engine for a helo not being that significant, you need to take this fact into the equation....

Helis are difficult. Troublesome equipment drastically compounds that, and adds greatly to the learning curve. Adjusting a heli engine for proper running is NOT the same as needed for an airplane; you have much to learn. If you are fighting a balky engine, along with the thousand and one other things you have to watch on a helo, frustration is not far away.

Having said that, there are folks who have good success with TT heli engines, so its your call. But I think you're stacking the deck against yourself, especially if you plan to put a plank engine in your Hawk. The carburetors are definitely different.

I'm impressed with the Hawk Sport. I just ordered one yesterday as a trainer for my grandson. But never forget that a helicopter flies on the engine, and for a successful flight, EVERYTHING has to be right. Helicopters are very complex; not rocket science, you can do it, but you want to make things as easy as possible.

Steve