Prop Pitch Measurement - WHERE is it Important to measure on blade??

[Tim_Duggan]

Tim

i cant remember exact, but i do remember at 35000+rpm it is good for approx 3-4mph

over the 40x53,

i have one for my outboard...

regards Aaron

Thanks Aaron!

Somehow I just don't think the OS outboard muffler is going to let me make 35Krpm :lol: :lol: a peak of 26-27K is a little more likely I think ( I've got to invest in a logger!). I'm looking for something in between the GR 40x53/2 and the Octura 1440 to work with, maybe 42x55 reduced to 40mm?

 

[shoboat]

Tim,

X-442 B/C will work very well with reduced cup and diameter change

until you are happy with the RPM from the engine.FYI,38mm is pretty

close I have found.

Darin,

.7 Radi is the place to measure.

Need to know what kind of boat,Hydro? Mono?

I like to work with the cup right on the trailing edge,.7radi

Leading edge pitch and the progression to the trailing edge.Hydro? Mono?

Center of blade pitch and it is hardly ever close to the manufactures

specs. So this is why I measure it with a Wood pitch gauge. As far as

blade profiles and custom cuts they all do different things.Cambering is

very important and not many understand it very well, but I think Terry Keeley

is starting to learn more about it whether he knows it or not. It is critical to

how well our propellers work or not work. Don from HydroComp is a very smart

person and I know some of his clients. Now maybe Andy will chime in.

Propeller work is very interesting to me, but there is a ton of ever changing

information being presented around the world. I am currently working on some

very interesting test results as well as some new designs. New designs are pretty

costly, so I can only afford so many at a time.

Have Fun Testing,

Happy Holidays,

Mark Sholund

Props-4-U

 

[Chris Wood]

mark,

can you explain what you mean by chambering?

thanks

chris

 

[shoboat]

Chris,

I do not have the time right now to write a paper on propellers, but I can tell

you to start looking up information on the internet and library on propellers.

Google: Propeller blade camber and read pages 1-6 to start with. Enjoy!!!

I have many hours of research on the subject and believe me there is so much to

learn just on basic propeller designs. I can tell you the blade camber has a lot

to do with our performance that we extract from our old designs. Another recent

article is about: Drag,boundary-layer and surface roughness characteristics of marine

propeller surfaces. These articles are pretty deep and can be very hard to understand

until you start to understand the basics of propeller designs. Over in Europe is where

most of the current research is being conducted.

Have Fun,

Mark Sholund

 

[Rigged]

While not on the subject of pitch..but after reading something about props i came acorss an article stating the hubs should be a small as possible.

What are those who do props thoughts on that? On the gas boats, have found bigger (fat) hub props to hold RPM better through the turns then props with the same blades, and a smaller hub.

btw Mark have not forgot about our convo...$$$ just got real tight right now