Project: Sailing Submarines - Catama-sub

thingiverse

<h2>The Ice Is Melting and I am Planning</h2> I needed to divert my attention today, so I spent a little while modelling a concept I had. It will be some time before I can test it, so I'm sharing my machinations here. Uses some files/inspiration from my other project: Sailing Bluenose Model https://www.thingiverse.com/thing:5513493 Check out my other cool stuff like mugs & cups here: https://WeCanDrinkTogether.com/ <H1>MAKING A USELESS TOY</h1> Inspired by "The Useless Box" and other useless machines, I thought it would be fun to make a submarine that sails! I'm planning to test this on some strong wind days and hope to get enough speed to plane on the fins and flat bottom. This would make it a <i>hydrofoiling</i> sailing submarine. <H1>Hull Profile</h1> Hull profile is a SPICA airfoil, cut along the chord line, mirrored, and then cut lengthwise with a circular extruded cut. The hull is then truncated along the bottom to provide for a good printing surface, and supportless wall angle. The submarine "sail" qua conning tower is an ellipse extruded on a draft angle. It was centred on the centre of mass of the hull prior to it's addition, so it's a good indicator of CoM/CoG post-print. The CoM should also represent (approximately) the centre-of-pressure for the buoyant hull as well. The SPICA shape should provide for decent enough drag properties in air and water, and is generally suited to a broad range of low Reynold's numbers. It also provides a good distribution of buoyant pressure, ideally have the vessel ride slightly nose-up. Based on my printer's settings, it should weigh-in at about 154g. The overall hull (including conning tower) should displace about 234mL (=234g) of water. Meaning there should be about 34% of the hull out of the water when there are no pressure effects from wind or movement. Most old-school subs were most fuel efficient when about 1/3rd out of the water, so that should be just about right. <h1>Post Your Makes</h1> <h2>See Also...</h2> https://www.thingiverse.com/thing:5939552 <h1>Updates!</h1> I just printed a mini version, primary float test went OK! Hull floats slightly nose up, but that's before 2 extra masts, sails, and a pair of rear rudders. I think in the end it will all work out under the wind pressure of sailing. I think I may be able to sail this mini version in the tub if I set up a fan.