4-stroke Rotax carb heat

[VNugget]

So far I've flown 3 different types powered by a 4-stroke Rotax, and 2 of them don't have carb heat. And the one that does, the manual said there's no need to use it in normal ops.

So what's so different about them from the carbs on 'traditional' engines that they're not even equipped with carb heat?

 

[ultrarunner]

So far I've flown 3 different types powered by a 4-stroke Rotax, and 2 of them don't have carb heat. And the one that does, the manual said there's no need to use it in normal ops.

So what's so different about them from the carbs on 'traditional' engines that they're not even equipped with carb heat?

Hmm....it's likely it's aircraft-installation dependent. I'm not a rotax guy, but I've flown different airplanes with the same engines and the AFM's from time to time differ.

 

[belchfire]

There are two kinds of icing in carbs. Venturi icing where the moisture is cooled by the pressure drop and freezes. The other kind is fuel evaporation icing where the temp drop from the fuel going to the vapor state resulting in ice formation.

My suspicsion is that there is something about the design of the carb that makes icing not that much of an issue.

The rotax is a relatively new engine. You have to remember that the design of most aircraft carbs is essentially unchanged since the 1920's and '30's.

 

[Huggyu2]

I just got a demo flight in a Remos G3 at Oshkosh. Rotax 912S on it, and a manual carb heat. On takeoff, the engine started sputtering at about 300'. The demo pilot grabbed the carb heat, and the problem was solved.

 

[CherryBomb]

I have got a Rotax 912 ULS on my Zenith and I have no carb heat. The carbs are mounted toward the rear of the engine facing aft. I suppose it is very warm back there...