openprop help

Boats, Jet Skis, Kayaks etc., including hovercrafts
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aethyr
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openprop help

Post by aethyr » Aug 04, 2017 1:33 am

Does anyone have experience using openprop? I have some questions.

1) What exactly does the ship speed parameter do in the GUI? There are no other parameters, like ship size or weight or drag coefficient or anything. Just speed, so how does only having the speed parameter provide any useful input?

2) The paper on openprop mentions being able to build a NURB model from the openprop's output files. It seems to me they manually constructed the model in a CAD program, using the propeller numbers as a guide. Is there a way to automate this somehow? There is actually a 3d rendering of the prop in the matlab GUI, so clearly the model data is there somewhere. I suppose I could try to hack into the matlab code, but maybe there's an established way that I'm not seeing.

aethyr
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Re: openprop help

Post by aethyr » Aug 05, 2017 4:12 am

I've made a little bit of progress. I looked in the openprop source and found a parameter to output rhino3d and solidworks macros and I was able to hack the code so that those files are now created from the GUI.

However, it looks like the macros are old and some of the commands are not supported by the latest version of rhino3d, in particular to the ExtrudeCrv command uses a PointTo mode, which the latest rhino3d doesn't have and none of the options are equivalent. The other problem is that Rhino3d isn't free and I'm using the trial version, so trying to fix the code to output proper rhino3d commands isn't worth it.

I use fusion360, which is free for hobbyists, so maybe I'll try writing a module to support fusion360 output.

I'm not sure if anybody here uses OpenProp, but it seems like a great little tool for designing efficient props. You can first run a study, which will take some basic inputs, such as size range, power and rpm range and then output a range of different propeller graphs, each with different efficiency curves. You then choose the most efficienct design, run the design mode and it produces a 3d model of the propeller that you can manufacture...that is, if you can actually get a usable 3d file, which where I'm currently stuck at.

markula78
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Re: openprop help

Post by markula78 » Aug 05, 2017 7:16 am

Hi

I have also tested openprop but i get some error when i run the program.

Error using fprintf
Invalid file identifier. Use fopen to generate a valid file identifier.

Error in Make_Reports (line 420)
fprintf(fid,'\t\t\t\t\t %s \n\n',filename_input);

Error in OpenPropSingle>execute (line 1197)
Make_Reports(pt);

Error while evaluating UIControl Callback

So i cant see the 3D propeller.
I also use fusion 360 and i have seen that other people working with hydrofoil board also uses fusion. If you can get the 3D files from openprop to fusion 360 so i can 3D print it!.

aethyr
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Posts: 66
Joined: Mar 20, 2017 7:39 pm

Re: openprop help

Post by aethyr » Aug 06, 2017 12:41 am

markula78 wrote:Hi

I have also tested openprop but i get some error when i run the program.

Error using fprintf
Invalid file identifier. Use fopen to generate a valid file identifier.

Error in Make_Reports (line 420)
fprintf(fid,'\t\t\t\t\t %s \n\n',filename_input);

Error in OpenPropSingle>execute (line 1197)
Make_Reports(pt);

Error while evaluating UIControl Callback

So i cant see the 3D propeller.
I also use fusion 360 and i have seen that other people working with hydrofoil board also uses fusion. If you can get the 3D files from openprop to fusion 360 so i can 3D print it!.
That error looks like its because it couldn't open the output file for some reason. What is the full path to your project and project name? What version of matlab do you have? Are you using windows or linux?

fusion360 support is going to take a while, if I even try to do it.

markula78
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Re: openprop help

Post by markula78 » Aug 07, 2017 6:02 am

aethyr wrote:
That error looks like its because it couldn't open the output file for some reason. What is the full path to your project and project name? What version of matlab do you have? Are you using windows or linux?

fusion360 support is going to take a while, if I even try to do it.
ok thanks, i got it to work now. It means that is not possible to design a propeller wih wrong parameters.
Eks. At 16 Knots, 25Kg push, about 2500W required.
Propeller:
Hub diameter 48mm
160mm prop
3 blade.


Prop: Power:
150mm - 2700W
140mm - 2700W
120mm, by incresing rpm to 6000 2700W.
So i dont think is that precise. But trace the 2D profiles and maybe you can get a desent propeller.
Attachments
160mm, 2D.jpg
160mm, 2D.jpg (108.78 KiB) Viewed 284 times
160mm.jpg
160mm.jpg (65.28 KiB) Viewed 284 times
160mm2.jpg
160mm2.jpg (89.49 KiB) Viewed 284 times

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