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Posted by: SolomonGrundy ® 10/14/2005, 15:07:22 Author Profile Mail author Edit |
I am working toward building a human powered vessel capable of extended open ocean crossings of 90 days or more. I have been working with a local designer and we have a model that will be a 20' aluminum double ender. It will displace a tad more than 3500 lbs. It's 5/8" Monel shaft will turn a large diameter 2 bladed carbon fiber prop, the design of which has not been finalized. It is estimated that the human power-plant shall deliver between 1/6 and 1/3 bhp. I am assuming that an optimum prop rpm will fall in the 200-250 rpm range.
I have initially considered dual pedal cranks (recombant style)chain coupled to a geared sprocket on an intermediate shaft connected to the prop shaft by a 1:1 bevel gear. But recently the notion of a worm drive coupled to a flywheel either directly geared to the prop shaft or directly on the end of the prop shaft has come up. Ideally this could be set up so as to be powered by a pumping motion (hand powered rail car style)or even better...both pumping or pedaling to provide for additional flexibility. A great part of what makes this such a challenge is the need for simplicity, reliability and ease of maintenence in the finished product (for obvious reasons). Anyone who has any feed back, please chime in. |
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Posted by: SolomonGrundy ® 10/24/2005, 14:54:24 Author Profile Mail author Edit |
Randy, thanks for the input, but you are way off the topic. |
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Posted by: randykimball ®  10/15/2005, 00:07:45 Author Profile Mail author Edit |
Something that has always caught my attention and interest, that I have never had the time to follow up on and figure out:
A fish moves through the water with so little effort and does not use a prop. I am convinced that a machine can use the physics that move a fish in a mostly submerged version similar to the way a world war II submarine sat when at snorkel depth. It has to have much more involved than wiggling a tail. The fluid dynamics of what makes the fish dart on pressure ridges or whatever need to be studied. Somebody is going to be famous and win several world awards when they finally crack this trick. I’ve watched fish in an aquarium many hours trying to get a fresh clue to no avail. Yes, they flick the tail to accelerate, but there is such small action required. I feel like the men that watched the birds wondering if man would ever fly. ….food for thought?… If you make the machine you are thinking of light to keep the weight down for reduced drag you will get beat to death in a rough sea /not be able to pedal or crank/ or blown off coarse by almost any wind. If you make it heavy and stable it will be a large mass to move with large HP requirements to make any serious headway... a quandry. -randy-
The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by randykimball at Sat, Oct 15, 2005, 00:14:56 |
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Posted by: S_Ogle ® 10/20/2005, 20:39:26 Author Profile Mail author Edit |
Randy,
Yes, I agree... well done, just like the concept of lift was discovered by analyzing air speed over the top of a wing vs. the bottom, movement thru water should be similar. Unlike a birds wing, which depends heavily on resistance, and surface area, a fish's body is covered with scales and a slimey coating. A bird wing, and the feathers, are designed to create a lot of surface area, to optimize the interaction with the surrounding air. Yet a fish's body, excluding the tail for now, is streamlined, and the slimey coat acts to minimize resistance. I believe this is why the tail of a fish is different than it's body, not simply because it is more flexible, but the surface is actually different. Aiding to generate thrust in the water. Do you happen to know what the fastest fish are? S. Ogle
the opposite of a bird, in that the surface area is minimized. |
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Posted by: randykimball ® 10/21/2005, 21:28:29 Author Profile Mail author Edit |
they tell me the Barracuda, ... long and dart shaped. The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them. Modified by randykimball at Fri, Oct 21, 2005, 21:32:28 |
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