I am trying to determine what type of motor to buy that can spin my load at high speeds without overloading it, but really, evaluating this is not my forte. I know this is not sufficient information but making all relevant assumptions I would like your help in sizing a motor based on the following information:

  1. A set of 30 100kg discs arranged vertically.(mass can be split to 300kg per set)
  2. The motor could use gears.
  3. The load bearing shaft is attached to a magnetic bearing.
  4. Desired constant speed of 3000rpm.
  5. Time taken to reach such speed 3 days.
  6. Should be the most energy efficient method.
  7. The surface roughness is about 0.2 micrometers.
  8. The discs are coaxial.
  9. The discs are 1m in Diameter and 0.1m in thickness. Surface roughness stated above applies.
  10. The discs are equidistant from each other (surface to surface) at 0.12m.
  11. All other factors: cost, vacuum chambers, risk/hazards are to be assumed.

With this information I would like a rough estimation of the motor rating to spin and maintain the load at given speed, energy consumed to maintain such a speed, gear ratio.

Edit: I have changed the parameters slightly. I just want something base; some rough idea of size range of the motor. Guys the motor rating is our key concern a large motor is undesirable; all other factors are not a problem. So be it a vacuum chamber, superconducting bearings or complex gearing these are not a problem provided the motor rating remains low(hence why I said most energy efficient method). If the energy requirements for keeping such a high mass device spinning are low enough, budget stops being a problem regardless.

Thorough analysis and risk assessment is scheduled for a much later date and will employ the services of required experts. For now though we just wanted to have rough idea of what we would be dealing with.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – Wasabi
    Aug 7, 2021 at 21:41

1 Answer 1


You are basically talking about reverse Tesla pump. huge torques could come to play to rotate and eject the air in between the disks.

It is involves advanced aerodynamics.

here is a tesla pump refrence link.

Tesla pump


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