Quote:
Originally Posted by martin417
If you look at this paper (yes it is old, but the science is still good) you will see that it is possible to gain about 50% to 75% in thrust, as well as improved efficiency by building a shroud. Since you have to protect the props in something for safety anyway, why not make it an asset? Here is a picture of the fiberglass shroud we made for the prop:
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Good stuff. Careful what you call old
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Be aware that 9,000 RPM is about 138% of the manufacturers safety limit for a 10 inch slow fly prop.
The battery issues (and wiring) are very important. While the internal resistance of the battery is spec'd at 10 milliohms it behaves more like 5 to 10 times that at higher currents and low frequencies. It's best to design around 11 volts at the motors to account for all of the drops.