Posted for "Ed Anderson" <eanderson@carolina.rr.com>:

Barry, I am certainly not a water pump expert.  However, the one assumption that Paul made was that because the rotary mechanical water pump apparently consumed 16HP (or something like that - maybe it was 13 HP) at 6000 rpm that it took 16HP to provide proper cooling flow rate.

Now, IF that assumption is in error, in other words, if most of that 16 HP is consumed by pumping losses against coolant flow resistance, turbulence, caviation - you name it or anything else that DOES NOT contribute to the actual coolant flow, then the actually powered needed to provide adequate coolant flow may INDEED be much LOWER than the power the mechanical water pump actually consumes.

This would apply to all mechanical pumps.  So IF the above is correct AND only a small amount of current/power is needed for the actualy required coolant flow then indeed 16-20HP may be saved by the electric water pump.

I must admit that I am highly surprised to find that it might only take 7.5 amps.  Heck my high pressure fuel pump (one) takes almost that much current.   If it were 15-30 amps I would be less surprised, but 7.5 does surprise me.  However, that is fairly easy to measure, so I have to assume the current figures must be correct.

I could be all wrong about this, but that's the way it appears to me.  I mean we have the evidence flying so what more can I say.  Even if its not 0.135 HP its clear that real world data regarding EWP on the flying rotary has clearly shown it is entirely feasible and does not need to draw several hundred amps as Paul's calculations indicated.  Your figures are no better than the accuracy of your assumptions (trust me - I know {:>)

Best Regards


Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com