This formula is not based on theoretical conditions. The data to derive my constant for cats (36970) and hydros (33300) was from a pool of 30 actual and running setups. So the results yield an average speed for a particular type of hull and the data pool doesn't represent "best case scenarios or runs." If anything, the formula doesn't overshoot speeds. This way, it keeps the numbers modest. You may be pleasantly surprised if your actual setup goes a few mph faster than calculated speed. I've also found that any differences between manufacturers may vary between 1-2 mph in most cases when testing.
jcald2000, that's a great reference. The Offshore calculation is within 3% of my measured results. My formula undershoots as it is an average of various setups, the Offshore formula overshoots as it is a best case scenario. Both have their uses, but to use the Offshore formula you have to be online - can't just compute on a handy calculator or phone.
Martin, I didn't post the mono formula because I've only tested the formula for cats and hydros. The essential difference between the various types of boats is their hull slip factor. Martin, for monos, based on the hull slip factor monos vs cats, I would place the mono factor around 39600. Again, I would want to test that number to verify it and average it for different manufacturers in the water under normal conditions so that it gives a result within 1-2 mph of the GPS readings. For monos, the formula should be close to:
mph (mono) = [Prop Pitch] x [Prop Dia.] x [kV] x [LiPo V] / 39600
Mean Machine Cat: 9XL, 4S2P, CC120, M545 (50mph) -- DF22 Hydro: 8L, 3S1P/4500, CC120, x637 (49mph) -- M-1 SuperCat: 1521/1Y, 6S2P, CC240, x447 (61mph) -- SV27 Mono: stock setup, 14-cell/4200, x642 (42mph) -- Micro Scat Cat: 28-3600, 3S1P/2100, Turnigy 60, x430 (41mph)
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