Abstract: Improved ultralight aircraft constructed with a tubular keel extending over the length of the aircraft from forward of its wing to the tail thereof. The aircraft includes a cantilever engine mount which is carried on a pair of mounting plates extending longitudinally from the forward end of the tubular keel. The propeller shaft, driven by the engine through a speed reduction arrangement, is supported in a bearing disposed on the engine mount. The aircraft includes a cage assembly for the operator's seat and has upright tubular rails and a pair of longitudinally extending side rails mounted on a shock absorbing landing gear. The landing gear has a nose wheel and a pair of laterally spaced rear wheels. The rear wheels are carried on the outer ends of a pair of longitudinally spaced, transversely extending tubular members.