Prop pitch and power

[BHChieftain]

Hi,
I *think* I know the answer to this question... but I'm curious--

Is there any condition where a prop with a lower total pitch would pull more amps than a prop with higher pitch? I know that it is possible to get more speed out of a lower pitch prop if it hits the rpm sweet spot, but what about overall power (and therefore heat) load?

For example, I'm running a kinda dull x442 prop on a fastech on lipos and my esc to motor connectors (6mm bullets) are getting too hot-- is there any chance a really sharp/thinned x642 prop would run any cooler?? I wouldn't think so but...

Chief

[Flying Scotsman]

The answer is no if both props are ballanced and sharpened... the X642 will demand more from the power system all other things being equal.

Douggie

[Fluid]

The answer is yes - maybe. If the higher pitch prop gets the hull moving faster so that it is higher out of the water with less resistance, then the motor rpm can be higher - meaning lower a amp draw. This is not common but it is seen and reported with certain setups - I have seen it on occasion myself.

For example, recently the Insane FE-30 with UL-1 motor has been reported by several owners to run cooler on larger props. This seems counter-intuitive, but it makes sense if you think about the boat speed relative to motor rpm. Just don't assume that it will always happen - it will not.


.

[BHChieftain]

The answer is yes - maybe. If the higher pitch prop gets the hull moving faster so that it is higher out of the water with less resistance, then the motor rpm can be higher - meaning lower a amp draw. This is not common but it is seen and reported with certain setups - I have seen it on occasion myself.

For example, recently the Insane FE-30 with UL-1 motor has been reported by several owners to run cooler on larger props. This seems counter-intuitive, but it makes sense if you think about the boat speed relative to motor rpm. Just don't assume that it will always happen - it will not.


.

Thanks Fluid!
I have noticed that the Fastech on x442 does ride rather wet... I've played with the strut angle to get her out of the water a bit more, but I've hit the limit on that. I've been reluctant to try the x642 since x442 was running rather warm, but I'll give it a go and see what happens.

Chief

[ENCORE MAN]

I recall a response by Darrin reminding us the FASTECH prop is not a surface drive prop and the handling and temps would be affected by over propping. I followed his advice and ran x438 and x440 props and found I could get around the course just as quick but with lower temps all round. BG