I have a back up Heli engine, OS 50 SXH and I'm thinking of getting a Nexstar, is it alright to use this engine? Any comments or suggestion will be greatly appreciated.....

i think the heli motors are basicaly just a bit more pwerful, and can have varying drive shaft length. that was what i was told, but i dont fly helis(YET!)

I always thought it would be smart. A no spin idles would be awsome...

Pilot Chad - the heli engine would still spin the propellor at idle. The reason that the helicopter rotor does not spin at idle is that the clutch plate is not engaged.

The heli engine will have a ton of go. With the extra cooling fin area it is possible, but unlikely, that it could be overcooled by the high-speed slip-stream of the aircraft. I wouldn't use a heli engine in a fixed-wing A/C in cold weather.

The trend nowadays is for heli engines to be missing a key component needed for use with a propellor; the prop drive washer that fits over the crank shaft. IIRC, the 50 SXH does not come with this part. I'm also reasonably certain that the part made for the plank version of the 50 SX will fit the SXH fine. You can order that from The Empire.

As for "shock cooling" due to the enlarged heli head; not an issue, britbrat. I've put a 32 F-H and a 61 SFN-H; both of which have the big rectangular head; on planks and flown them in all weathers with no problems. They just look sort of dorky on an airplane...

The main differences are the carb and the cooling fins.

Heli engines have a carb thats optimized for mid range where we spend most of our time, airplane carbs are setup for top end.

The head also has the cooling fins. Some engines, not sure about the 50, use a shorter crank shaft and you would also need to find the thrust plate and woodruf key which sometimes find a way to disappear when your using the engine in a helicopter.

That's usefull info -- thanks

Hey, I've put on OS.61 heli in an airboat and it performed great in all weather, infact it started easier in the winter than my .40 K&B. I was able to swing a large prop if i can remember correctly and it had tons of power. The rectangular head may look goofy, but the engine is designed to be inside something so how about cowling it in?

Thanks guys. Learned tons.