Large Ornithopter Drive

thingiverse

This is a functional, mostly 3D printable, rigid wing ornithopter propulsion system intended for 3-6kg radio controlled aircraft. (the mechanism itself weighs 1.5kgs with the motor and wing spars) Typical ornithopters have the following problems: 1. They use an inefficient membrane wing to approximate wing articulation, or they use a heavy wing articulation system that cannot vary the amount of articulation with flapping frequency and flight speed. 2. They have one pair of flapping wings; this produces a cyclic loading on the motor that requires the motor to be sized for a peak torque that is much larger than the average torque. This design addresses these problems via the following: 1. The design has two pairs of wings that are 180 degrees out of phase, this dynamically balances the device and results in a much lower peak torque requirement. 2. The design has torsion springs that articulate the wings in proportion to the lift force on the wing. This means that a faster flapping frequency and slower airspeed result in a greater articulation angle. The current manufactured prototype used the following non-printable parts: 1. M3x40 bolts (32) 2. M5x50 bolts (2) 3. M3x16 screws (14) 4. 6805RS (machined to 1in dia) bearings (3) 5. 626d bearing (4) 6. 6mm dia x 70mm steel rod (2) 7. 6mm shaft collars (4) 8. 1in x 300mm aluminum tube for the drive axil 9. 1/2in x 400mm aluminum tube for the structure (3) 10. 1/2in x 350 aluminum tube for the wings (4) 11. 1m length x 300mm chord NACA 1408 foam wings (4) 12. 3mm steel rod for the landing gear (2) 13. 850 kv motor, 60A esc, 3s LiPo battery 14. Rest of the plane (nose, tail, servos, receiver, etc.) It is likely that you will have to modify the design to fit your choice of wings, motor, and bolt sizes. For the motor and wing sizing the file “ForcesAndTorques_chart.csv” list simulation results that can be used for sizing the motor and wings. The given gears have a reduction of 53. A basic pinion gear is provided and it is up to the user to figure out how to attach it to the motor (a propeller adapter works well)