In need of remembering prop number conversions.

[gearhd48]

After 5 yrs of being away I have forgotten how to convert prop numbers. Example: an Octura M 442 compared to the OSE 4214250 42mm or 1.65 with the 2.32 pitch. This getting old thing sucks when you can't remember! LOL

[fweasel]

The octura 3 number props are (pitch ratio in inches)(blade diameter in mm). So the 442 has a 1.4 pitch ratio and is 42mm in diameter. The OSE prop you mentions is 42mm in diameter, 1.4" pitch ratio.

[gearhd48]

I thank you for the reply, but how is the total pitch calculated? also how did you get the pitch ratio out of the total pitch ratio? I know there's a mathematical way of finding this, which is what I need to relearn. Thanks

[TRUCKPULL]

42mm in diameter, 1.4" Average pitch ratio.

42mm X 1.4 = 58.8mm per. RPM

LJ

[gearhd48]

Thank you Truckpull! Now the two props I gave as an example are apparently both 1.4 pitch x 42mm, but according to specs the OSE one it has a TOTAL pitch of 2.32 ,and the Octura has a 2.64 TOTAL pitch. I'm sure this should have a performance difference right? I'm dangerously assuming the slight difference is that the 2.64 total pitch might be a little more aggressive. Right? How do they get the TOTAL pitch numbers?

[TRUCKPULL]

1.4 pitch x 42mm, Octura has a 2.64 TOTAL pitch. Sorry but the 2.64 TOTAL pitch is on a 642 prop = 42mm Dia. and a 1.6 pitch NOT a 1.4 pitch prop.

Diameter: 1.65" (42mm)
Total Pitch: 1.4x1.65=2.310"

LJ

[gearhd48]

Thank you sir that is what I needed! My mistake on the 2.64.