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Archive for August, 2013

# Some mathematical relationships for predicting the effect of power system changes.

Posted by Nereth | Aug 12, 2013 @ 06:50 AM | 4,492 Views
Just some simple formulas that dont take into account much by way of real world phenomenon like losses, but they can be useful for small changes:

Thrust:

1) Thrust from increased RPM, changes ∝ n^2
1) Thrust from Increased average speed due to diameter, changes ∝ D^2
2) Thrust from Increased length due to diameter, changes ∝ D
3) Thrust from Increased Chord, (not sure the symbol but calling it C) changes ∝ C. We assume this is proportional to diameter, therefore changes ∝ D.
4) Thrust from decreased average AOA, changes ∝ D^-1
5) Thrust from increased pitch, changes ∝ P.

So in total we get this:

Thrust ∝ N^2*D^2*D*D*D^-1*P = N^2*D^3*P

Current

Current is linear with torque, torque linear with thrust, so by the same token:

Current ∝ N^2*D^3*P

For 0 resistance or inductance,

N ∝ V
and also,
N ∝ Kv

Therefore,

N ∝ V*Kv