Engineers from four countries developed a small X-shaped ornithopter with a mass of 26 grams with controlled tail and energy-efficient mechanical transmission. Experiments have shown that the new transmission allows to increase the efficiency of flight by 40 percent compared with the propeller mounted on the same motor. The design of the tail and of the wings allows the unit to fly vertically and horizontally and sharply to unfold, say the authors of the article in Science is Robotics.
Most of the small drones with the capability of vertical takeoff and landing (VTOL) have the design of the quadcopter. This type of apparatus is well researched and it has a lot of control algorithms, also the multicopter mechanically quite simple. But engineers are working on alternatives, not only with the design of the aircraft type, but also with the design of ornithopter that flies by flapping wings, like birds (though often they used four wings arranged in the form of the letter X).
Studies with simulations showthat the ornithopter is aerodynamically more advantageous scheme. In practice, the ornithopter uses a multi-element mechanical transmission between the engine and the wings, which due to friction and tilt gear has lower efficiency than a simple screw fastening on the shaft of the motor in multi-rotor aircraft.
Engineers from Australia, China, Singapore and Taiwan under the leadership of Ki Keong Lau (Gih-Keong Lau) from the National Jiao Tong University improved the design of mechanical transmissions for the ornithopter to improve its efficiency. In General, the device has a standard design with X-shaped wings of a polymer film and a thin bearing elements at the edges and in the center, giving the wings rigidity. The wings are driven by one motor.
From other advanced miniature ornithopter, such as the DelFly or KUBeetle-S, new ornithopter is markedly different tail, and moving: both the plane may tilt in the right direction, working as elevators and directions.
The main improvements of the mechanical transmission related to the stabilization of the motor shaft and the wings with the bearings and polymer frame. This allows the rotating shafts to remain on its original axis almost without deviation. Another improvement is that at the joints of the wings and the Central part of the case has no loops. Instead, all three parts are combined into one monolithic, in which place loops just reduced thickness. This allows you to use the elasticity of the polymer, especially when returning the wings back after they went to the maximum angle after stroke.