User talk:Vincecate/BallHouse

Truth is I found a 36 cm (14.2 inch) buoy on the beach that is just perfect for modeling this at 1/25th scale, so I will have to model it. And since I will be testing a model of this design I decided to write it up to match the model.  :-) The idea is growing on me the longer I think about it. Vincecate 03:35, 10 July 2008 (UTC)

Concrete on inflated balloon

How about making the sphere by spraying fibrous concrete (shotcrete) on an inflated balloon?--Vtoldude 19:10, 10 July 2008 (UTC)

Maybe. I think you still need some rebar. Setting it up so it stays in place, but in the middle, is a bit tricky but probably there is a way. Vincecate 18:57, 28 August 2008 (UTC)

HDPE Plastic

I think HDPE plastic could really work for this. A ball is a strong shape. They use the plastic for kayaks and some small boats. It is heavier than fiberglass but really tough. With some "carbon black" in it the sun does not bother it. Vincecate 18:57, 28 August 2008 (UTC)

I dont know, i have strong practical concerns. Making these things is going to require custom machinery i think: ive never heard of rotomoulded things anywhere near as big. This makes protoyping hard. Secondly, its going to be hard to build an actual house in there. The shape itself isnt really helpfull, but how do you attach a floor to this structure without significantly weakning it? Due to the novelty of this approach, there is going to be an endless stream of practical questions like that which you will have to overcome. And what are the advantages over a concrete cylinder? Eelco

I have never heard of any rotomold this large either, so yes it would be custom. You could make a prototype by inflating a big ball and then putting fiberglass on that. You can heat two pieces of HDPE and fuse them together. So attaching things inside might not be bad. The advantages over a cylinder seem to be that we don't need heave plates or a truss. It seems like the waves have an easier time tipping a cylinder. For sure a cylinder needs a heave plate, not sure it needs a truss yet. More testing is needed. I believe a ball could be made from concrete too if HDPE does not work out. But I think HDPE will result in really low cost. You don't need all the steel that concrete does, the mold does not need to be nearly as strong since an inch of plastic is not as heave as 6+ inches of concrete. Also the rotomold only has to be on one side where a concrete mold would have to be both sides. And you should be able to reuse the HDPE mold ever couple hours and concrete would take longer to be strong enough to remove the mold. Vincecate 11:18, 4 September 2008 (UTC)

Measuring accelerations

Question: how do you measure absolute acceleration of the models, in the video ? The technique seems great for simulating rotational stability against waves, but not for simulating the heaving and bobbing that might be felt on the inside.--Jesrad 10:39, 1 September 2008 (UTC)

I agree. I can compare sideways acceleration between models by the angle the red water is slanted at. Also, if the water were at 45 degrees that would be 1 G acceleration to the side and I believe that scales to 1 G at the full sized. Or another way, a similar thing of water on a full sized version would slant about the same. So we can sort of measure felt sideways accelerations. But it really mixes in with the up/down accelerations too. So it is not very accurate. If you know of a better way please let me know. Vincecate 14:04, 1 September 2008 (UTC)

I know wave tanks do this by placing a checkerboard background behind the models and using a fixed position camera, but that's not going to be practicable with open sea testing, unless you have someone zooming on the model from the shore and a three-legged support to put the camera on. Putting an accelerometer inside the model could work, too, as well as being more accurate. Also, how can I send you a little funding ? --Jesrad 13:36, 3 September 2008 (UTC)

It seems like a "G Data Logger" is priced reasonably enough that it is the way to go. http://www.microdaq.com/occ/pendant/pendant_g_data_logger.php You could send me funding support using my paypal account. My paypal email account is firstname@lastname.com with firstname vince and lastname cate. Thanks much! Vincecate 20:11, 3 September 2008 (UTC)

My Paypal account is frozen (them bastiges like to freeze accounts when they receive any sizeable amount of money so they get interests on your money) so I sent you a few bucks from SecondLife, so don't be surprised when it tells you that your "credit has been processed" or something ;) --Jesrad 19:32, 9 September

2008 (UTC)

Thanks! I just checked and it is not there yet. Will let you know when it gets in. Vincecate 16:17, 10 September 2008 (UTC) Ok, I see it now. Thanks again! Vincecate 19:03, 17 September 2008 (UTC)

Polyhedron

About the polyhedron model: what about truncated octahedron ? It is the only regular tesselation of space (regular honeycomb) which has an elemental shape that approaches a sphere. I had selected it as the ideal basic building block for a space station made out of large water bags tied together, but I figure it could also see good usage as the basic floating building block for seasteads clumping together. --Jesrad 15:07, 10 September 2008 (UTC)

Don't think packing together is going to be so easy. I think I want more faces and closer to spherical. The smoother it is the more it gets the strong structure of a sphere and the less wave splashing there will be. Vincecate 16:17, 10 September 2008 (UTC)