Fan Modifications

In another thread, there was some interest in modifying the interior fan in a non-Pod camper and a Fantastic Fan (like in the Pod). Having a Coleman TT, I replaced the OEM noisy/ineffective fan and modified it to run slower by installing a 10 watt/10 ohm resistor.

The two ideas in question are (I think):
1. Ways to slow down the Heng's Vortex single speed fan
2. Ways to further slow down the 3 speed Fantastic Fan (like the Pod's)

One question asked was about potential heat (from the modification). Yes, heat is a concern when choosing a resistor and possibly heat build up in the motor when running a slow speed. The 10 watt resistor that I used is overkill but, it's what I had on hand. I can't foresee a situation where it would ever get hot. My Vortex runs roughly about the same as the Fantastic Fan on "medium" speed setting. Being oversized and with still plenty of air flow, it all stays cool.

So, all electrical gurus out there, see pages 5 and 6 of Techntrek's new camper thread for further info. Let's see if we can solve the 2 questions above.

Some issues that come to my mind are:
amp draw at start up
amp draw at running speed
resistor size/value/fixed/variable VS relative RPM of the fan motor
at what point does it not provide enough current to start the motor
efficiency - amp draw VS motor speed

Speed - I can only give a subjective account on my Vortex and that is:
It seems to operate at about 75-80% of the manufacturer's speed.

Any thoughts folks?

PS - The person with the best ideas will win a free membership in this forum for all of 2015!

Why not just use a pot?

and then I read the rest of Doug's post..