2 ms·
That's kind of a misconception. You can use a whole bunch of smaller rotors to have nearly the same efficiency as a single rotor of the same diameter (okay fine
by Robotbeat 5y ago
That's kind of a misconception. You can use a whole bunch of smaller rotors to have nearly the same efficiency as a single rotor of the same diameter (okay fine there are also Reynolds Number effects from going smaller, but not as important in this context). The difference is roughly the packing ratio of circles, about 90%. VoloDrone takes this approach.
- idiotsecant 5y agoFor a real-word cargo flight there are climb conditions and cruise conditions and a fixed-pitch rotor can't possibly be efficient at both - it will be tuned for a given rotation speed and a given airspeed across the disk. At any ambient conditions outside those regions efficiency will suffer. variable-pitch rotors can adjust to high efficiency in cruise and good climbing performance, depending on requirements. Electric cargo vehicles are neat, and maybe the loss in efficiency is acceptable, but you undeniably lose efficiency with a fixed rotor design.
- Robotbeat 5y agoBut all of that has maintenance overhead, and whether hover or translational flight dominate the energy consumption determines which to optimize… there’s no great efficiency loss to going fixed pitch unless these two flight regimes have near equal average energy usage per flight. Additionally: Variable pitch is one thing, but swashplate flight is another. There’s no significant efficiency reason to change blade pitch multiple times per second. Much slower variable pitch propellers, aka on horizontal flight aircraft, is much lower maintenance and overall complexity than a swashplate based helicopter.