Quote:
Originally Posted by Molten
When it says comparable. It says that it is in respect to the danger of the blades. In reality, it really isn't saying much.
Also, I know it is the blade size that makes it dangerous. I also know it isn't the rpm that makes it dangerous. Lets compare to electricity. The current alone won't kill you and voltage alone won't kill you. It has to be together. However, there are standards for both. If nothing else, they could set up a simple formula that would allow for various rpm/diameter possibilities while still restricting the real danger.
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Prop size isn't the issue, nor is RPM. It's people not understanding the forces that they are attempting to control.
Unfortunately, there is no simple formula that makes a prop of a specific size safe at a specific RPM. There are many factors that go into max prop RPM. While diameter is one of the factors there are others such as composition of the prop (wood? Nylon? etc ...) as well as pitch, and design (Master airscrew, APC, etc). What is safe for one type is dangerous for another.
All props should have a specification sheet that will tell Max RPM for that prop. I would expect teams to have a safety margin built in so that the prop cannot ever exceed that speed (In fact I would stay well below the manufacturers recomended max RPM).
Again, teams will need to prove that their design is safe and that the protection they have put in will work in the event of a catastrophic propeller failure. Anything less should not be allowed on the field.