On Fri, 28 Oct 2005 18:33:17 -0800, MK1 wrote:

Logan Shaw wrote:
Ad absurdum per aspera wrote:

Accounting for real-world efficiency, the actual power usage curve, and
other things you'd want to tease out if you were designing or
specifying equipment, rather than just getting a quick calculation onto
the right order of magnitude, makes for big equations with a lot of
moving parts.


Agreed. I was just trying to imply that an hour's worth of friction
might change the energy by an entire order of magnitude.

On the other hand, if it truly takes an hour to get up to speed,
then maybe friction is only a small part of the battle...

- Logan
There is no friction.An eddy current drive would be magneticly coupled.

The energy difference between what the motor supplies and what the
load absorbs is dissipated as heat in the eddy current clutch. Just
like a friction clutch would except that there are no wearing
surfaces.

At the instant of startup, the drive is dissipating all the power and
the load is absorbing none. At the instant of full speed, the load is
absorbing all the power and drive is dissipating none. (This assumes
no electronic ramp drive to the eddy current clutch) The actual
solution to the stored energy problem is a nice little calculus
problem but one can approximate by assuming that half is dissipated
and half absorbed by the load. That's a spit-load of energy! I'd
certainly not want to be in the building if the rotor disassembled
itself.

John

---
John De Armond
See my website for my current email address
http://www.johngsbbq.com
Cleveland, Occupied TN