# Accleration time for electric supercharger

1. Apr 3, 2012

### arslanpersona

Hello everybody..

I am stuck with a question here. I have to estimate time for an electric supercharger to reach from 40-120k rpm. Impeller inertia is negligible.
Max torque=2 Nm, bearing drag profile=0.001 Nm/krpm, diameter=30mm, Lenght=100mm
Shaft is solid steel with density =7.85 kg/cm3

2. Apr 3, 2012

### Staff: Mentor

What is the context of the question? What is the application? What is your technical background? We can be of more help if we know more...

3. Apr 3, 2012

### arslanpersona

I am a mechanical engineering graduate. Dont know much about electric motors but will understand if somebody put me in right direction.

4. Apr 3, 2012

### jim hardy

You can calculate its moment of inertia

but what about the wind drag? It's a fan or pump of some sort. You are better versed in those than i am.

And what do we know of motor? All motors have a torque vs speed curve. It will accelerate until torque = drag, and torque = f(speed).