Some years ago I bolted a 3-inch metal hing between engine mount and firewall of an own-designed funfly-type model. The system created much amusement at the field when my flying pals at first thought the engine was about to "fall off" when I tested it with the enging running in the pits - they promptly named it an "engine-wobble system." It was servo-operated, giving varying side-thrust up to a maximum of around 20 degrees to starboard. The throttle lever was on the hinged side so the varying angles made very little difference to the throttle cable. The only thing I remember about flying with this system is that the model could knife-edge with the port wing down for as long as I wanted because the off-set thrust just held the model in knife-edge. All I had to do, after rotating the "engine-wobble's" switch, was adjust the engine speed to prevent the model climbing or diving. Once set correctly it would maintain its attitude and altitude without any "fiddling needed. Then I was free to concentrate on steering it around with the elevator - it was "so" easy to do. Knife-edge loops (from port-wing down only of course) could be made very tight real easy too. It was a lot of fun and it produced some amusing-looking effects on aerobatics too. Writing about it here makes me think I should try it again!

Tony