.21 Proto speed, I think. Usually they use a Novarossi .21 2000. No pipe allowed, just a straight stack up to 6" I think. There is also a regional North West region that has an F2D speed class. They use the combat motors on a profile plane. I have looked for results but have been unable to find any. I guess it isn't too popular.
Last edited by aspeed; 05-16-2014 at 04:13 AM.