Another No Fuel Piston Ornithopter! The wings flap sideways on that guide rail and they are powered by 3 sets of 5 powerful pistons. It is again stabilized by a gyroscope. I tried to make it not have a gyroscope and instead, a turning mechanism, but if you put rotators on any of the moving parts the wings become too flimsy and my other idea was too heavy to get of the ground. It flies pretty well and can climb at pretty high speeds but you have to control the throttle pretty well to hover or land. Don't have the throttle too low while in the air. Controls are as you would expect.
Edit: new version: https://www.simpleplanes.com/a/XQGHLL/Hummingbird-Ornithopter-Improved