Quote:
Originally Posted by AeroMcAeroFace
So you are saying that the car would accelerate faster if the blades were stationary and not connected to the wheels? At least in the beginning?
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Yes! That's it!
Suppose the gearing is set up in such a way that the propeller blades push the air back at half the speed of the craft.
Then of all the force on the propeller trying to push it forward half gets lost by the gearing turning the blades against it. When the rolling resistance and other friction sources are less than that, there is still something left to push it forward.
Once you see it it really blows the mind.
When in motion the propeller blades wing effect kicks in and they become more effective, like as if the surface of the sail increases. So a stationary propeller is good to get rolling but you want it to turn immediately after.
The craft in the video has adjustable gearing. I guess in low wind you have to reduce the gearing as the other sources of friction are relatively large. And maybe you want oversized gearing to be able to brake or even back up against the wind.
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