3D printed Hull


#1

I have been thinking about an ROV for a while, joining this forum, and purchasing parts has moved me closer.

Living in a Narrowboat I have a fair amount of access to 3 / 4 meter deep water, but my interest is in going deeper. As an active member of my city's hackspace I have access to the 3D printer, and the Lasercutter, and being miles from the US makes the purchasing of the kit expensive.

I have chosen to build my own pressure vessel and ROV hull from materials I have access to. I have taken measurements off the laser cut files, and design ideas from Ion.

If you could have a look at http://skippy.org.uk/openscad-openrov-design/ I would appreciate any feed back and thoughts people have.


#2

Skippy, you design looks great! If you are following the guidelines and design examples provided by Ion your ROV will have excellent performance. I have scaled my ROV size to fit my 3D printer its smaller. The ROV is still in sea trials at the moment so far so good.

https://www.youtube.com/watch?v=FHhFzj1bZEY&feature=youtu.be

Mark


#3

Hi Mark. Thanks a lot for your words, but you are the one who did it.

Mark has built quite an impresive version of the ROV. Get in contact with him :-)

Regards

Note: Skippy don't hersitate asking for help if needed.


#4

Thanks Mark, Ion,

Ion on my blog comment you mentioned there being hulls better suited to being 3D printed. Can you recommend any examples, or sources?

Also I managed to get the Kort nozzle to print well, so if any one else wants that its here - http://skippy.org.uk/kort-nozzle-test-print/


#5

Hello Skippy:

The hull designed by Mark, is a lott better than the one I posted.

As I told you, I was thinking on sheet laser cutting and not on 3D printers.

I've read on your blog, that you are planning to use a nozzle of the 37 series.

Well, at first sight it could help, but, due to the high speed-lenght rate of Mark's rov, that duct, may work against, and not with thrust.

If not a 37, the 19A has similar performances, both are the most used accelerating ducts.

I've attached a simple graph showing how the KtN coefficient (Nozzle thrust coefficient) changes with J (Advance coefficient).

Both 19A and 37 nozzles KtN have been plotted.

Note that J= Va/(ND), Va= advance velocity, N= propeller revs per second, D=propeller diameter.

Hence, from N and D, the useful speeds range can be found.

Please note, as well, that the example propeller has the same physical specifications than the Graupner, but belongs to the KPP series, a lot more suited for working into a duct.


Regards


#6

I have found a application called Hull Form - http://www.softpedia.com/get/Science-CAD/Hullform.shtml, With that in collaboration with using Autodesk’s Fusion360 - http://fusion360.autodesk.com/about (Free Hobbyist license) I will try and re-design my 3D printed hull.

OpenSCAD is a great application for designing simple things for printing, however a PITA for complex shapes.


#7

Hi Skippy:
The best free hull fairing and design software is, from any point of view, FreeShip. A lot more complete and powerful than HullForm.
FreeShip is even used by profesional Naval Architects. It includes many calculation utilities.(Stability, speed, propellers, …) And many external plugins that can be added from it’s site (Structural loads, added masses, …)

Check it at:
http://www.hydronship.net/index.php?lang=en

Im sure you’ll find it more useful than hullform.

Regards


#8

I have grabbed a copy, I will have a play and see how I get on with it, thank you for your continued help Ion.


#9

You’re wellcome Skippy.
I enjoy helping amateur “Naval builders” :smile:

Dont hersitate asking

Regards