HP to WATT to THRUST

CDBarry----
Thanks for info. I am way past the "matching" phase. I have built a racing hydro and have purchased a custom made prop that is allegedly specificaly for the class of boat and the engine I am using.I am now trying to predict the performance of the boat.
I believe that if I could get efficiency vs speed, my prediction inputs will be complete.
(by the way, "complete" is not neccessarily the same as "accurate")
What is Blount-Hubble,an algorithm?, a text book? authors of a paper? In any event how do I get a hold of it to use. Is it in the form of General Propeller charts as were used for aircraft props. Any help pointing me in the right direction is appreciated

 

For a hydro you need Radojc's algorithm.

Check out PSOP at SNAME, and in the papers section for both references.

 

dont know why i'm on http://www.grc.nasa.gov/WWW/K-12/airplane/thrsteq.html again, trying to keep up i guess

 

ETA0 ... ok! But what about ETAR and ETAH ?

RANCHI Otto

 

ok, propeller efficency is "ETA" and not "Estimated Time of Arival"
what the abriviation stand for i have to check, like ETAO, ETAR and ETAH
Geez, not so easy to learn something bout thrust...

 

It is not a question of abbreviation but I want only say that the thrust needed from a boat to reach a speed is not only prop's efficiency.
The values of prop's efficiency derivated from cavitation tunnel tests are theoretical because the propeller has to produce thrust behind a body (ETAR) and the speed of the boat is not the same as the speed of the water at propeller (1-w) and so on....
This was my thougth Yipster... only this....

RANCHI Otto

 

thanks for clearing these wonderings, i find "thrust" rather interesting but complicated