11 comments on “A really interesting concept bike and engine system.

  1. Wow. I didn’t expect you to put that up?

    Wankel bikes next?

    As a paintball player who uses these scuba tanks regularly, I can say that this bike makes vastly more sense to me if they ditch the standard 88 Cubic foot aluminum 3000 psi tank and took a 4500 psi or greater carbon fiber tank of similar size. People aren’t getting this bike to be standard. The weight savings and range would be very worthwhile, and they could be filled to 3000psi if that is all that is locally available.

  2. I can see this being good for the trials bike types.
    Lots of torque low weight.

    Air has some real advantages over electricity. Amish people have made a bunch of air powered appliances which are supposed to have far superior longevity. Search for “Amish Electricity” to find some examples.

    I am not a super environmentalist or anything but I like the idea of stuff that keeps producing on it’s own. If you had some big storage tanks and a scuba compressor connected to a wind mill, you could more or less power a bunch of tough work vehicles indeffinitely for free. I am thinking of Gator type vehicles for work around the farm. That kind of thing.

    It would also work pretty well for a short commute bike.

  3. I think that carbon-fiber tanks are actually a combination of aluminum and carbon fiber.

    One definitely wants to use a paintball tank and not a scuba tank. Scuba tanks are designed for breathing air and salt-water environments, so they’re overkill. One would have to stick with DOT regulations for inspection, and so forth, which add to cost and overhead, or have the laws changed.

    Filling a scuba tank to 3500 psi takes about 30 minutes, but that may be different for a tank that nobody’s breathing from. Much easier to compress and fill from the atmosphere.

    An accident is much more likely to damage the valve than rupture the tank. High-pressure air escaping a valve is still dangerous; it can spin a tank around at high speed or punch holes in material. It’s still worth considering.

    • Carbon or fiberglass HPA tanks are a thin aluminum bladder with the fiber woven over them, and baked. They use them for firefighting and for scuba too. Scuba divers also have several standards including a popular class of steel tank rated to 4500 PSI for DIN.

      They are all rated to way under their burst pressure and have to be checked regularly and certified.

      The reason for the standard aluminum tank is it was the tech over 30 years ago and the two big tank manufacturers agreed on a standard. Also, most of the compressors only go up to 3K psi. However it is pretty common that a nominal fill of 3000 psi is really about 2700. It is worse if the tank isn’t kept in cold water while they fill it and then topped off after it sheds heat.

      The main reason people use the old style is that they are common and cheaper. Not that they are better.

  4. I’m sorry, I just don’t understand this compressed air concept. Surely compressing air would have to be one of the most energy consuming / inefficient processes going?

    • Our current energy problems are less an issue of production than of storage. Wind systems for instance produce tons of electricity, but can’t be depended on to when you need them. Thus they have to be supplemented with the dirtiest kinds of coal power to respond to the shortages in time. On the flip side they are often producing electricity when it isn’t needed. Batteries are nasty, cost prohibitive and wear out.

      Big companies are investing in kinetic energy storage because it is ok to waste the bulk of wind energy if you can ensure power when you need it. Air could be one method of storing spotty electricity.

  5. The beauty of compressed air is that it is a form of energy storage that is staggeringly clean (certainly a lot cleaner that decayed nickle and lithum batteries), easily transferable from a larger central tank (say at a gas station). The filling stations could be AMAZINGLY flexible. Once the large tank is in the ground, it could be recharged (continuously) any number of ways. Electric pumps. Fossil fuel powered motors/pumps, which could run on gasoline, hydrogen, propane, natural gas, diesel etc etc. and those pumps could be supplemented with solar during the day and wind turbines round the clock. I’m sure a lot smarter people than me are working on the physics.

    Also if you run out of pressure you could have a small onboard fuel source and compressor to get you charged up long enough to get to a station (or your home compressors) to prevent total stranding common with all Electric.

    The more I think about this the more I like it.

    • One issue with filling as you go is that compressing and transferring compressed air releases heat and makes friction. Thus heat expansion frustrates filling quickly. Usually you have to fill, allow the tank to cool, and then top off. Traveling long distance this would mean that each time you stop for fuel, you could fill your vehicle to full say 5,000 psi. go grab a coke and use the bathroom, come out and your bike would read 4200psi, due to cooling which would roughly equate to 3/4 full. This would require either massive tanks or frequent stops to top off.

      Oh, and one tiny leak would leave you with an empty tank by surprise.

      The other major issue is that compressed air relies on a bunch of moving seals that are close tolerance and wear quickly. A gas engine is sort of an air motor too, but there is so much expanding gas that it is ok to waste a fair amount. I am sure these air motors need lube freqently, and to have seals replaced on a regular basis. No doubt the oil itself stays a lot cleaner though.

  6. Good points Zach… I tend to forget that gasses (even air) do strange things when compressed and decompressed at such high pressures. Heat would be huge of course. I suspect that seal technology might be something that could be overcome with even a tiny fraction of the resources devoted to battery storage.

    • I noted that the french air motor in your next posted air bike actually uses this to advantage. From what I can tell, it boosts the use of the air for power and range by using a gas burner to heat the air as it expands in a chamber between the primary regulator and the final regulator. Thus effectively having more air in the storage as a boost mode.

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