OpenROV From The Open ROV community
I have been looking to build an ROV (underwater Remotely Operated Vehicle) for a while, There will be other blog posts on this in my blog some where.
I have been looking over the designs for the OpenROV and have signed up on the forums. there is one guy on there called Ion
I’ve been working at the Naval Industry 22 years by now. I think during that time I’ve passed through all stages. From OGC (Oil-Gass-Chemicals) surveyor, to ship’s design.
He seems very knowledgable on a variety of subjects, and as part of that had raised comments regarding the ROVs hydrodynamics. and has written a number of posts relating to improving the shape.
Since I was planning on self building a fair amount of my ROV, I have been CADing up my shapes in OpenSCAD based on the BOM and the laser cutter files.
I plan on using a 3D printer to produce the hull for mine, so far this is my design as it stands
Maritime Research Institute Netherlands (MARIN) No. 37 Kort Nozzel
I am going to use Kort Nozels rather than plain cowlings for surrounding the two propulsion propellers
A ducted propeller, also known as a Kort nozzle, is a propeller fitted with a non-rotating nozzle. It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited diameter. It was developed by Luigi Stipa (1931) and Ludwig Kort (1934). The Kort nozzle is a shrouded propeller assembly for marine propulsion. The hydrodynamic design of the shroud, which is shaped like a foil, offers advantages for certain conditions over bare propellers.
Advantages are increased efficiency at lower speeds (10 knots), course stability when sailing astern, and increase of cavitation. Ducted propellers are also used to replace rudders.
The profile is Maritime Research Institute Netherlands (MARIN) No. 37, which sacrifices some forwards thrust for better backwards thrust.
I will also be making my own end caps for the E-Tube, on the HacMAN laser cutter.
I will be printing a test hull at some point soon, and making a first trial version, once I am happier with the maths, and the set up I will realise full code (and work towards optimisation).
November 21, 2014 at 14:37
Hi all:
I’m that “ION” quoted above.
Check Mark’s (from the OpenROV comunity) development of those ideas. He has done quite a good job refining and optimizing the hull and arrangements.
Ah ¡ Thanks for your possitive comments.
Regards
November 22, 2014 at 09:38
Hi Skippy:
I’m Ion, the one quoted above.
When I posted the “more hydrodynamic” hull, I was thinking on planar plastic sheets building. Straight lines are the result of that building procedure limitations.
If you are going to use 3D printing, the general hull shape can be improved a lot.
Check suitable profiles for the expected speed (around 2-3 knots) and dimensions, that can allow for the electronics required volume helping, at the same time for pitch stability.
Take care with the weights and their distribution, static and dynamic stability are the goal to achieve.
Thanks for your words about me.
Kind regards
November 22, 2014 at 15:57
I will have a look at hull design in three dimensions, I assumed that the teardrop cross section would be a start.
Can you give recommendation where and what I should be looking for?
November 27, 2014 at 16:57
Hi Skippy:
Please contact me at the ROV’s site, and don’t hersitate asking for any help you could need. I enjoy helping ROV’s builders.
About your question regarding the profile selection. The thickness to chord ratio choice will be limited by your design ROV dimensions. But, the correct profile choice depends on many things that afford a deeper conversation.
Kind regards