OS still makes the rotary engine http://www.osengines.com/engines/osmg1400.html . This is the second generation, the first was a bit of a dog. It's power is comparable to a decent .45 airplane engine. The max RPMs listed are 18,000 but those who have them say if you push that limit you will quickly wear out the rotor seals. It suffers from cooling issues and a high price tag. For the money, $340 at Tower, one could buy a really nice boat engine!