OS has come out with the OS15GTHZ gasoline engines for helicopters but from different gasser forums, it seems to have had a lot of teething problems. A flying mate had fought with one over the summer in his JR SG700. After sending it back to OS in Japan three times he finally gave up on it an got himself a Century Radikal G-30V2FBL with the HWC/Zenoah motor and is very happy with it.