Castle 1717 - RC-Monster Forums

Pdelcast · 12.11.2009, 04:10 PM

Sorry guys -- we just realized that the car versions of the 1717 were incorrectly listed as having a 5mm shaft.

About the 45000 RPM limit -- at 45000 RPM the magnets have a centripetal force of over 1500lbs/sq in on them (about 30,000 Gs -- seriously...) -- that's about the physical limit of the kevlar reinforced magnet structure. To go any higher, we would need to get a stronger material than Neo/iron/boron magnets. :(

We just don't know (yet) how to hold the structure together at above 30,000 Gs.

nitrostarter · 12.11.2009, 04:14 PM

Quote:

Originally Posted by Pdelcast

Sorry guys -- we just realized that the car versions of the 1717 were incorrectly listed as having a 5mm shaft.

About the 45000 RPM limit -- at 45000 RPM the magnets have a centripetal force of over 1500lbs/sq in on them (about 30,000 Gs -- seriously...) -- that's about the physical limit of the kevlar reinforced magnet structure. To go any higher, we would need to get a stronger material than Neo/iron/boron magnets. :(

We just don't know (yet) how to hold the structure together at above 30,000 Gs.

Maybe you guys should contact NASA. They test that stuff out!

lutach · 12.11.2009, 04:35 PM

Quote:

Originally Posted by Pdelcast

Sorry guys -- we just realized that the car versions of the 1717 were incorrectly listed as having a 5mm shaft.

About the 45000 RPM limit -- at 45000 RPM the magnets have a centripetal force of over 1500lbs/sq in on them (about 30,000 Gs -- seriously...) -- that's about the physical limit of the kevlar reinforced magnet structure. To go any higher, we would need to get a stronger material than Neo/iron/boron magnets. :(

We just don't know (yet) how to hold the structure together at above 30,000 Gs.

Very thin carbon fiber tube will do the trick. It's been used in very high RPM motors.

Pdelcast · 12.11.2009, 05:31 PM

Quote:

Originally Posted by lutach

Very thin carbon fiber tube will do the trick. It's been used in very high RPM motors.

Yes, we tried that. Kevlar actually worked better in our testing, up to about a limit of 30K gs. We've also tried stainless steel sleeving, and titanium sleeving -- they worked well but increased eddy current losses to the point where it wasn't worth using the sleeving.

You really don't want to go above about 45KRPM anyway, hysteresis losses become really big really fast at those commutation frequencies.