Where to find Bp-delta diagrams?

[tommc]

I have looked at several threads here relating to propeller design, as well as reading Dave Gerr's Propeller Design book, but can't find any indication of where one actually buys or downloads the Bp-delta diagrams. Gerr includes 4 charts in his book, but one assumes there are other charts available.
1. Can anyone suggest who publishes and/or sells these charts?
2. Was this work done by the government and therefore in the public domain?
3. I've also seen several references to coefficients for equations fitted to the curves but have the impression that these were derived by individuals performing least squares fits to the published curves? Is that the case or are coefficients published somewhere like the charts probably are?

[CDBarry]

The curves and the coefficents are in the two (oops ... three) volume PNA from SNAME (the current one). They are also in PSOP, also from SNAME.

Note though that the curves are for B-series (big ship) props, which have slightly different characteristics than commonly available segmental boat propellers, so that a calc done with B-series props will tend to result in a slightly overpitched boat prop.

The Blount-Hubble coefficients are more appropriate for small boat propellers. They are published in a 1981 SNAME paper. (And are in PSOP).

[DaveB]

What's PSOP stand for?

Originally Posted by CDBarry

The curves and the coefficents are in the two volume PNA from SNAME. They are also in PSOP, also from SNAME.

Note though that the curves are for B-series (big ship) props, which have slightly different characteristics than commonly available segmental boat propellers, so that a calc done with B-series props will tend to result in a slightly overpitched boat prop.

The Blount-Hubble coefficients are more appropriate for small boat propellers. They are published in a 1981 SNAME paper. (And are in PSOP).

[tommc]

Thanks,

I searched for SNAME and found the Society of Naval Architects and Marine Engineers. Then on their website searched for PSOP which turned up the Propeller Selection and Optimization Program.

I assume just the coefficients are in the PSOP and not the curves? Am I to understand that all coefficients are in the program, including the B-series?
Thanks again.

Originally Posted by CDBarry

The curves and the coefficents are in the two volume PNA from SNAME. They are also in PSOP, also from SNAME.

Note though that the curves are for B-series (big ship) props, which have slightly different characteristics than commonly available segmental boat propellers, so that a calc done with B-series props will tend to result in a slightly overpitched boat prop.

The Blount-Hubble coefficients are more appropriate for small boat propellers. They are published in a 1981 SNAME paper. (And are in PSOP).

[CDBarry]

PSOP comes with separate data files that have the coefficients for various types of prop series. The program uses these files, and the manual also contains them, so with the (pretty good) manual and software, you have a good solution at a very good price.

[tommc]

Thanks, I really appreciate the advice and will probably order the manual and program.

Originally Posted by CDBarry

PSOP comes with separate data files that have the coefficients for various types of prop series. The program uses these files, and the manual also contains them, so with the (pretty good) manual and software, you have a good solution at a very good price.

[tommc]

Still looking for advice on original question #2.

"Was this work done by the government and therefore in the public domain?"

i.e. Can the data be used commercially say in a program or a book? If the work was government funded then I understand that it's Ok. But, of course, if it's funded by private interests (such as SNAME) then it requires permission and perhaps royalties or fees. Any opinions or advice appreciated.

[DaveB]

Hi,

I'd be very surprised if it's been done by the government in a public domain sense... I think you can use them for calculations if you reference your sources, but I'd imagine there'd be some royalties involved if you used them to develop a software package...

Sorry I can't tell you for sure... Just my two cents...

If you're serious about it I'd recommend contacting SNAME.

Dave

Originally Posted by tommc

Still looking for advice on original question #2.

"Was this work done by the government and therefore in the public domain?"

i.e. Can the data be used commercially say in a program or a book? If the work was government funded then I understand that it's Ok. But, of course, if it's funded by private interests (such as SNAME) then it requires permission and perhaps royalties or fees. Any opinions or advice appreciated.

[CDBarry]

The original work was done at MARIN, in Delft. The coefficients were developed by Van Ossannen later. All this is cited in PNA, Volume II, which you can get on library loan or from SNAME.

There is no reason you can't use the scientific results to develop other products or publications. (And SNAME, Hydrocomp, and I, to name a few, have developed software that does just that.) That is considered "fair use"; facts themselves are not copyrightable, only their expression 9though it is appropriate to give credit in the references.)

[CDBarry]

Actually, to be correct, Dr. John Diadola used them when he wrote PSOP, not SNAME itself. The program was developed by Dr. Diadola, on his own, and the manual developement was funded by SNAME Panel SD-2 (Computer aided ship design).