Propeller resources 1

[bobbyjack]

Hi, I am not an engineer but a CNC programmer by trade and have been commissioned to program and develop the processes to machine an unlimited hydroplane propeller. I already have a CAD model of the part and feel fairly comfortable about programming it but I would like to better understand the principals and geometry that go into the design of a propeller. I think it could help me to do a better job for my customer. Are there any good introductory books on this subject? Any help would be appreciated.
Thanks in advance

 

[TaylorC]

try the propeller handbook. I don't know the author, but it is a good introductory reference.
Taylor

 

[known100]

Aerospace:
Propeller resources

TO: bobbyjack

Try to pose the following words to: Google.com
aerospace propeller knowledge handbook manual
Yes, you can enter in the space these words as such!
If you put and and and, then they will be omitted anyhow.
Of interest to you will be (among others!):

http://www.monmouth.com/~jsd/how/htm/bibl.html

and:

http://www.physics.ohio-state.edu/~kurth/avi/pages.html

The latter is "Lisa's Aviation Links" and you can link to a lot!

Good luck and once turning, take good care!

Known100 (Dredging) Yes we also work with propellers (called screws)

 

[Kenneth]

Don't know if you've seen it, but you might want to take a look at thread321-15535...

 

[Techno97]

I don't think you will find very much in any books. Most of the high performance surfacing props are built by those who have built them by trial and error. This is how the different types were discovered.
Most of the information will cover submerged props and not the cyclic loading of a surfacing prop. The general information such as rake, pitch and other details will be covered but will not give much insight into a Cleaver design. All aspects for a Cleaver will be changed from the example given. The prop your building is the bumble bee of the water.

I assume this to be a Cleaver design. This is stern lifting prop with a flat square vertical trailing section and a high rake. It would be used on Hydros or other tunnel boats that get lift from aerodynamics as they don't require any bow lift from the prop. It is terrible for getting on plane but better at speed.
Surface condition is important, it shouldn't be polished.
The square trailing edge is for shedding water from the prop blades to reduce drag, as is a surface texture.
Any surface marks should travel from hub to tip rather than front to back. These can become stress risers and snap a blade. This would be the only reason to polish a prop but will make it slower. The blade is loaded on entering the water then unloaded when leaving it with no balance to the load from the other blades as they are in the air.

A Chopper is form of round ear, both are bow lifting props and are the type that is usually described.

As far as I know there is no performance prop made that doesn't require hand blueprinting.


You can try these links for the terms and functions.

http://www.simplicity-marine.com/surfprop.htm

http://www.ballisticprops.com/MIWheel/HowToTech/Terminology/pterm_4.htm#rake

 

[bobbyjack]

Thanks all for your replies. Techno97 you were right, it is a cleaver type design. What sort of surface finish should I leave? 125 or better? Typically they have been polishing the props, mostly because the finishes they were getting were so rough and because they were getting stress cracking. I don't know which direction the prop was machined. The client has just purchased a brand new 5 axis machine to produce these props so I can pretty much machine them anyway I want to. I should be able to get a pretty decent finsh in the last stages of machining and I could run all the way from one blade tip to the next across the hub.
Thanks again,
Bobbyjack

 

[Techno97]

The machining direction doesn't matter its the final scratch direction. Although with the load this prop will see machining in that direction can't hurt.
I don't know the surface finish, this could always be changed by hand either smoother or rougher.