Joker
...chaos? Its Fair!
- Location
- La Porte, Indiana
I did a quick search and didn't find anything. What does the pitch of a prop mean?
For example: 13/18
For example: 13/18
Other Prop pitch?
- Thread starter Joker
- Start date
snowxr
V watch your daughters V
- Location
- Waterford, MI
Degrees. 13degree starting pitch / 18 degree ending pitch.
Joker
...chaos? Its Fair!
- Location
- La Porte, Indiana
So that would be a 77/167 degree angle (depending on which angle you look at) using the shaft area as 0?
And so a 16 would be straight 16 through the whole prop?
And so a 16 would be straight 16 through the whole prop?
The last number usually coinsides with the last half of the blade at the outside diameter. The first number never seems to match the front of the blade. All modern blades are cambered, this makes them cavitate less and run a lot smoother. The old straight blades were just that and would vibrate more at slow speeds.
Tyler Zane
Open Your Eyes
- Location
- Panama City Beach, FL
the number represents how far it would travel in inches in one rotation IF 100% efficient. just as the pitch on a thread of a bolt, its how far it moves in one revolution.
please correct me if im wrong, but this is how it was explained to me.
please correct me if im wrong, but this is how it was explained to me.
This is correct. Pitch (for any application, impeller, propeller, screw, etc.) is the distance (in inches as stated) that the object will move in a perfectly efficient system. Of course, actual systems aren't perfectly efficient and you lose energy from lots of factors.
As I understand it, a variable pitch, or increasing pitch, impeller has a smaller pitch in front and increases it so the initial water grabbed doesn't need as much force to be accelerated because it's not being pushed as much. As pitch increases the water is further accelerated now that it already has momentum to get the maximum exit velocity. When people say the low pitch is for low end and high pitch for top speed, this doesn't make sense because the water still moves throughout the entire impeller and thread no matter what speed. To make a specific pitch tune to a specific speed would be a LITERALLY variable pitch impeller that adjusts to engine rpm (such as centrifugal force throwing a weight that moves the impeller blades) so that the pitch you need is what you get. However you look at it, your exit pitch is your exit pitch for any speed. (Correct me on this last block if I'm crazy off, I don't design threads or "variable" pitch ones so not 100% sure)
