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#11
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Dumb Question
Why should a ducted fan/rotor not be capable of working in autorotation?
I never heard about that and cannot find a reason. How could it? With a duct around it, would you not have to descend straight down? And if you did, would the rotational mass of a rotor that small in Straight down can be a possibility. But if you can fly the thing, you can also tilt the thrust vectors. So just tilt it so that the airflow matches airspeed like in a heli. diameter, and designed to work at such a high rpm, store enough energy in free fall, to stop your descent when you applied collective to land? That's a design issue since it is not free fall. Otherwise it wouldn't be autorotation. The rotors/fans would of course have a windmilling braking effect. And certainly, the inertia has to be sufficient to allow smooth and preferably save touchdown as should be the case in every helicopter. Smaller and faster rotors are less effective and therefore need more descent rate (more power). That's fact, too. Compare the sink rate in autorotation of a Hughes 500 and a R44 (or the HV diagrams). |
#12
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Dumb Question
Stefan Lörchner wrote: But an interesting question is why nobody ever tried a supersonic rotor. Maybe it's easier to fold or stop the rotor than to make it strong enough and still efficient for sub- and supersonic speeds. Retreating blade stall. Linc |
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