Wow, some impressive calc's, i only ever went to school to "eat my lunch", not math !
Any way here is what Wolfston marine had to say on the Series II Swashdrive Jet.
We recently took delivery of two Swashdrive jets which have now been fitted into our free running model. I would like to take this opportunity to say how impressed we are with the jet construction and performance. The efficiency of your jets is almost twice that of the next best offering from Graupner.
I thought you might like some information on your jet performance in our model:
Propulsion system - Twin jet drives driven by twin Zenoah 260PUM engines
Model displacement = 28.9kg
Model Length = 2.185m
Deadrise angle at transom = 12 degrees
Model beam = 0.450m
Maximum speed (both engines fully open) = 23.6 knots = 12.13m/sec
Resistance of model @ 23.6 knots = 128N
Effective power = 128 x 12.13 = 1552W
Delivered power per jet = 776W
Delivered engine power = 2.32kW
Assume transmission losses of 5%, delivered engine power = 2.32 x 0.95 = 2.20kW
Jet Efficiency = 776 / 2200 = 36%
The best efficiency we have achieved to date with other jets (4 different designs to date) is 21%, so this represents a really significant improvement – well done!
I hope you find this interesting, Best Regards, Dickon Buckland.
Wolfson Unit MTIA
University of Southampton
Link to their websitehttp://www.wumtia.soton.ac.uk/