[MetalMan]

Originally Posted by What's_nitro?

Thanks everyone. Metalman I didn't see that bit about 30K RPM anywhere in the instructions for the fan. Thanks for mentioning it. It is good to know that the Lehner can take the beating without kerploding, but I guess I have to find another fan. I really want to stick with a single fan setup to save the extra weight. I need a MINIMUM 9# of thrust for the project because I'm aiming for at least a 1:1 thrust-to-weight ratio. Also, I want to stay with the 90mm size fan, or smaller if such a thing exists.

It's not in the instructions, I think of it as more of a mechanical limit. An older guy at the LHS I work at is a retired aerospace engineer, and big RC airplane afficionado, said that the fan unit shouldn't be used past maybe 15,000 RPM. But asking 9lbs of thrust out of it is most likely too much.