prop slip caluclator

[Almag6]

Whats the scoop on pluggin in prop pitch on the calculators? I've heard add one to Furys? true?

What about tempest?
Or a prop with cup added?

[21XDC]

Add a pitch for cup.... Some props turn stiffer than others because of different diameters, pitch progression, rake, cup height and blade area. Fury runs 1 pitch stiffer than a Tempest.

[Almag6]

Thanks. I have another question....I know its theoretical but hear me out.

Current numbers 25P, 1.86 gear ratio, 5900 RPM, 70mph
REv limitier is 6400. So, going by the general advice of running max RPM the motor is capable of ......
If I drop to a 23 pitch (same make and model)and bump RPM by 400rpm, and keep the same slip% (may or may not be true) the speed is the same (per calculator)??
I know I should bolt on a 23 and try it but dont have one currently.

[21XDC]

Depends on if the motor makes more HP at those rpms. If the same make and model prop run identical... Not likely.

[Travis]

Just wanted to throw my numbers and experience out there due to your post about the fury. I turn a 24 3 blade fury to 5990 @ 74.8 in some heat with my v8 mercury on 721 pretty heavy, same day same conditions I turned a 25 tempest plus to 6240 on the limiter @ 69.8. I am very confused on the Fury's pitch. I also ran a 26 tempest the next day to 6k @ 73 so its more like the fury is a pitch and 1/2 diff in my case almost 2 pitches different really. It is more like the Tempest 25 will flex down to a 23 in my case rpm wise and the fury 24 stayed true I guess.

[21XDC]

Um... No.. The 26P Tempest has laid back blades/Backwards pitch. This prop in stock form has higher slip and less lift than a 23, 25, and 27P... The Fury has more blade area... Wider blades.

[Travis]

So why does the 25 T run at 18% slip at 6240 and the 24 fury run at 5% at 5980 is what I am trying to figure out. The 26 ran closest to the 24 in slip and rpm than the 25.

[Travis]

So which is closer to its true pitch? the fury 24 or the tempest in a 25??? Very confusing here.