Which prop gives higher rpm?

[reiddo1]

Mounted on the same engine and operated under the same conditions, which prop gives greater rpm.......a 14.25 dia and 19 pitch or a 15 dia and 15 pitch?

 

[tpenfield]

Re: Which prop gives higher rpm?

Mounted on the same engine and operated under the same conditions, which prop gives greater rpm.......a 14.25 dia and 19 pitch or a 15 dia and 15 pitch?

15 x 15 would most likely give the higher rpm . . . the difference in pitch between the two probably outweighs the difference in diameter.

 

[jestor68]

Re: Which prop gives higher rpm?

Dropping 4 inches of pitch will increase the rpm by 600-700 rpm on average considering to the 3/4" increase in diameter.

Simple answer.......as pitch goes down, rpm goes up.

 

[Texasmark]

Re: Which prop gives higher rpm?

Realizing that pitch is the predominant relevant factor, you are changing diameter by 5% and pitch roughly 25%. Hands down, pitch wins; speed will drop and rpms may exceed the red line (upper rpm rated limit).

Mark

 

[Watermann]

Re: Which prop gives higher rpm?

Just to add my .02 to the great advice above, I have found that cupped blades also affect the motor's RPMs by getting more bite on the water, it lowers RPMs.

 

[Silvertip]

Re: Which prop gives higher rpm?

Just to add my .02 to the great advice above, I have found that cupped blades also affect the motor's RPMs by getting more bite on the water, it lowers RPMs.

That's because cupping is the equivalent of one inch of increased pitch. That needs to be considered when using a prop calculator.