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DD Prop Length vs RPM's

One Eyed Gator

One Eyed Gator

Well-known member
On my 472 dd I run a 72LXL38, with the same pitch but 74" what would the do to my engime RPM?

An idea on how much it would drop?
 
What does the length do, give more push or speed and is the pitch just the opposite?

I think I am asking the question correct.
 
If you are able to spin the long prop the same speed as the short prop both having the same pitch you should pick up some speed due to the increase in thrust output. if you are already propped to the max and then put a longer prop on with the same pitch your motor is going to drop some rpm's which could cause you to be slower in some cases. A longer prop should give you more push than a shorter prop provided you can spin it up fast enough. Typically people will go down in pitch as they increase length so they are able to still spin the prop up. example: I have a 72x30 for my direct drive 350, If I wanted to go to a 74 inch prop and still be able to spin it up like the 72x30 I would go down in pitch to a 28. I would gain some low end push but it would be slower because I have less pitch. on the other end if I wanted to go to a 70 inch prop and not over spin it I would go to a 70x32, wich would make me go faster than the 72x30 or the 74x28 but I wouldnt be able to run dry ground as good. hope this helps.
 
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