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This bike always has flat tires. The tires are quite large like motorcycle tires, but only a narrow band contacts the road, so they can be visualized teardrop shaped. The tires are inflated at the beginning of each ride in stationary mode. The pedals turn an air pump that inflate the wheels. The air
is pumped through the rotating hub into the tire.
Once the tires are fully inflated, and system pressure is over 120psi, air can be released. When air is released it travels through a pneumatic rotory actuator in each tire. This spins the tires in conjunction with inertia and gravity. Air can be directed to spin both, or either one of the tires. Ram air from front dead centre of the vehicle also supplements the supply by maintaining static pressure.
All the while, the rider is pedalling. The rider never stops pedalling and always maintains the same rate whether stopped, travelling down hill, or turning. Air is released by a standard motorcycle throttle, and the drive tires are determined by a three way switch with a fourth position for stationary mode.
Tata Motors Air Car
http://www.gizmag.c...-air-car-mdi/22447/
[UnaBubba, Jun 22 2012]
[link]
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I suspect the number crunchers will be along shortly to shred the assumptions, but I like it. |
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Sorta like bagpipes? Nice. |
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I get the part about being driven by the air supply,
but what's the benefit to keeping the tires flat? |
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No benefit, the first line is more of a tongue-in-cheek comment. I guess it helps me visualize the bike after all the times I've entered the garage to find flat tires. |
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Using oversized tires seems like the worst possible way to store energy via compressed air on a bike. |
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The only advantage I see is that if you expect the tires to always be flat when you start, and you just pedal to pump them up, it is in some sense more convenient than occasionally finding your tires flat. Of course if you actually have a leak in your tire, you could go for a long time without noticing except that you will be more and more tired at the end of each trip as the leak gets worse. |
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Oh, I see now. The tires are used to store the air.
Somehow I missed that part, and figured there would
be some sort of air tank. Hmm… I'm not so sure
about that part of the idea. Seems like you would
want to have a constant pressure in the tires as much
as possible, and probably the worst place to store
your high pressure reserve air is in the part of the
bike that takes the most physical abuse. Still, that all
just comes down to minor details. |
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I think the tires should be ordinary, but the frame should be inflatable. Obviously you can't ride it unless the frame has enough air pumped into it to make it rigid.... |
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Ive been thinking of lightness recently. Air power fits into
that paradigm. If you strip the frame of a road bike and
put in an air pump where the chain would be it's''already a
bit heavier. Nylon airlines will do the rest. But then there
is the problem of storing air. Why add an extra tank when
there are tires? Theres probably a few good reasons why
not , but to my mind if the air supply is constantly being
replenished ie the tires are constantly being pressurized
by pedalling, the tires can constantly operate the motor at
reserve pressure. |
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Given that the bike has a strong tubular frame, it
makes more sense to store compressed air in the
frame, shirley? It also simplifies the plumbing. |
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Mmmm, pedal powered bagpipes with a strong tubular frame and toroidal bag, I like this. |
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//Pedal powered bagpipes// Don't shoot! He's getting away! |
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balloons would not give enough backpressure. |
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Two problems, air pressure only has passable energy
density at high pressures and rubber tires are way
heavier than Al or FG over Al tanks. Also spherical
tanks are the best shape, toroids are going to be
really inefficient. |
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It's just a terrible idea. The tire changes pressure from normal to harder than a tube of steel to store a tiny volume of energy. The rider wastes 30%+ of their effort making heat. The bike is now equipped with heavy and finely crafted pneumatic equipment. The rider must learn to co-ordinate a hand throttle where they formerly had a brake. A puncture to the tire now represents a fatal threat to the cyclist and bystanders. The weight of the wheel/tire is substantially increased. The bike is now pointlessly capable of 2wd which is likely to cause the rider to loose control on slippery surfaces (think of "drifting" but in a bad way). The rider has no ability to increase output in an emergency, or operates with a fantastic reserve of power maintained at a further blow to efficiency. The need for lubrication and maintenance is increased dramatically. Repairs now require specialized skills and tools not widely available. Many parts must be made to high precision and of specialized expensive materials. The rider experiences no marked improvement in ergonomics or biomechanical efficiency. |
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Scathing critique really in halbakery style? I mean these ideas here are not my most obsessively protected, telling people I'm wanking when I'm really working on them, world secret police agencies are watching my every move, and I'm in a race with a secret competitor to complete, ideas. Those are Vernon ideas. |
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//It's just a terrible idea... need for lubrication and
maintenance is increased dramatically...Repairs now
require
specialized skills...The rider experiences no marked
improvement...// |
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Actually, what would be cool is a bike which can
be mounted on a stand as an exercise bike, and
which stores the energy as compressed air for the
next day's ride to work. |
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I know we've done this before, but compressed air
at 300 bar has a potential energy of 0.2MJ/litre.
Assuming that a strong hollow frame can hold 10
litres, that gives you 2MJ of energy. |
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Assuming that fairly energetic cycling is on the
order of a kilowatt, that gives you about 40
minutes of ride time. |
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For the average (non-elite) cyclist it's closer to about
0.4kW but that's still enough for
some motive power. |
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Tata, the Indian automotive manufacturer, has
already done this with a car. <link> |
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