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Old 9th November 2010 | 13:48
  #44 (permalink)  
awblain
 
Joined: Dec 2007
Posts: 633
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From: Pasadena
Energy of disk?

The question was asked what's equivalent to the energy of the blade disk?

Give or take -

Energy ~ 0.5 * number * mass * (radius)**2 * (omega)**2

number - relates moment of inertia to a hoop of same mass - say 0.6
omega = rotational velocity = assumed 600 radians/s ~ 6000 rpm (?)
mass = 50Kg (maybe a bit low?)
radius = 0.5m (?) - maybe OK including the blades.

Energy ~ 1.4 MJ.

At 70 mph (30 m/s) this is the same as the kinetic energy of a 2.6 ton truck.

So, a car at highway speeds is not going to be too far off the mark.

At 300 m/s, the same energy as a 30kg cannonball. At a radius of 0.5m and omega of 600 radians/s, the circumference moves at 300 m/s, so it's also very like three 10Kg cannonballs being fired straight out of the engine.
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