Air powered Bike?

[andy12]

Does anyone know if anybody has tried using something like these to power an e-bike?

The Shadow Air Muscle is a simple yet powerful device for providing a pulling force. It behaves in a very similar way to a biological muscle. When actuated with a supply of compressed air, they contract by up to 40% of its original length. The force it provides decreases as it contracts, and the first few percent of the contraction is very powerful indeed.

Link to shadow site http://www.shadowrobot.com/airmuscles/overview.shtml

Would it be possible to run a compressor off of an ebike battery to power the muscles? Could be noisy.
I`d love to play around with these, seems the power would be applied in a similar way to your leg muscles, but I have no idea how they could be attached to help turn pedals, any ideas?

 

[nuevomexicano]

You're going to need a whole lot of very compressed air to even go small distances. You're not the first to think of this, but the one's that have been built and discussed online don't seem to be great in range. Also, the air powered car that Tata (the Indian builders of the Nano) hyped back in 2008 seems to have never left the design stage.

In the end, isn't it more efficient to just use the electricity to power an electric motor than to use it to compress air to then power some sort of piston driven motor? Maybe there's a plus side if you could be lighter than a battery or last longer than a battery or not use electricity at all (flowing water to compress the air?).

http://www.instructables.com/id/Air-powered-bicycle./
http://www.treehugger.com/files/2008/04/air-powered-motorcycle-diy-moped.php

 

[pdf]

Would be pretty cool. I think the efficiency of the system would kill you though; inelasticity in the rubber, friction in the compressor, thermodynamic losses through cooling of the air as it is throttled, etc. However, I'd like to see a prototype. Go for it!

 

[StudEbiker]

The answer is STEAM! I have been playing with a steam driven trike in my head for awhile now. These guys powering 2-stroke motors off of air/steam are very interesting.

http://hackaday.com/2011/09/03/engine-hacks-convert-your-yard-tools-to-run-on-steam/

 

[GCinDC]

02 Pursuit motorcycle runs on compressed air

 

[dogman dan]

I think for some applications the compressed air motor might make a ton of sense. Forklifts for indoor use come to mind immediately. Not sure if the kind of tank you'd need for it on a bike would be lighter than a few packs of lipo though.

 

[GCinDC]

i didn't see any mention of what the motor is, or is it just a turbine of sort that drives the chain?

god would i love to load that up with lipo.

 

[Ypedal]

claims 60 mph, uhm... for like 10 seconds ?.. maybe ? :lol:

does look cool tho..

 

[Hugues]

....

Would it be possible to run a compressor off of an ebike battery to power the muscles? ...

for the fun of it ok, and to learn something.

But if you start with a battery on your bike, then the hub motor is probably the best in term of efficiency, meaning converting the energy of the battery into a forward movement.

Don't even need to run calculation to see that using the battery to run a compressor, which in turns..., da da da,....pretty inefficient.

 

[fechter]

Claims 3 hours of riding at 60kph. I bet that's a bit exaggerated, but even 2 hours would be pretty impressive.

The air motor is pretty interesting too.
http://www.engineair.com.au/index.php?option=com_content&view=article&id=2&Itemid=2

They claim over 94% efficiency in the motor (of course this doesn't include losses in the air compressor, which are going to be huge.

 

[liveforphysics]

9L at 4,500psi is 245watt-hours, and that's if you used it at 100% efficiency.

2 pocket sized LiPo packs worth of energy, but now you've gotta spend >1kw-hr of power to fill it rather than ~0.28kw-hr.

 

[The Mighty Volt]

9L at 4,500psi is 245watt-hours, and that's if you used it at 100% efficiency.

2 pocket sized LiPo packs worth of energy, but now you've gotta spend >1kw-hr of power to fill it rather than ~0.28kw-hr.

Reminds me of the natural-gas powered fan which created more heat burning the gas than the fan dispelled in the first place.

 

[Drunkskunk]

Whats the formula for figuring energy in compressed air?

And whats the maximum pressure you can compress normal Air to before it liquifies?

 

[liveforphysics]

Whats the formula for figuring energy in compressed air?

And whats the maximum pressure you can compress normal Air to before it liquifies?

This gives you an example of the calculation for a 12L scuba tank at 230bar having 1,242,000watt/seconds of energy, or 345watt-hours.

I did a very crude simplified one for there 9L tank to arrive at 245watt-hours. From this math, it would be 258watt-hours at 230bar.

http://www.combro.co.uk/nigelh/diver/tank.html

 

[sn0wchyld]

I remember looking at this a few years ago, though only in passing. From what I remember compressed air comes up short on almost all counts compared to decent Li batteries, apart from cycle life and power delivery. My memory's scratchy on the subject but the main problem is that they deliver power like a capacitor, ie, they can deliver a huge amount, but the power drops off at about the same rate as the % charge does. Ie lipo at 10% soc can sill deliver around 85% of the 'power' of full charge (3.6v vs 4.2v), a air tank would only deliver about 10% or less... Added to witch the efficency overall was low, and the weight (or was it volume?) per Wh was very high.

I read too that they have been used for dump trucks and the like, who need the extreemly high torque for taking off when stop/starting up steep hills, but in a bike I think they'd weigh too much for a decent range. Shame really, it'd be a cheap option, and 'recharging' could be made to be very quick.

 

[liveforphysics]

Claims 3 hours of riding at 60kph. I bet that's a bit exaggerated, but even 2 hours would be pretty impressive.

Damn straight it would be impressive.

180km traveled on 258watt-hours of energy.

2.3watt-hours per mile... Extremely impressive for a motor cycle, and no pedal input options. LOL!


This bike stores the energy of an out-of-shape person pedaling in a relaxed manor for an hour. If you're going to get 3 hours of motorcycle transportation out of that effort, it's EXTREMELY impressive. Or an obvious impossibility.

 

[Lock]

English mechanic and world of science
July 2, 1880
Scientific News

An American mechanician has invented a tricycle to be driven by compressed air. The reservoir is an iron tank which forms the seat of the rider; compressed air is pumped into this tank, and the tricycle is (to be) propelled forward at the rate of 25 miles an hour! The inventor proposes to erect "pumping stations in town and country" where the traveller can renew his pneumatic force at a "trifling fee." The dynamo-electric bicycle is quite out of the hunt now.

:lol:

 

[neptronix]

This idea sounds like a genuine waste of energy.

Everytime you convert one form of energy to another, there is a notable power loss.

 

[fechter]

Claims 3 hours of riding at 60kph. I bet that's a bit exaggerated, but even 2 hours would be pretty impressive.

Damn straight it would be impressive.

180km traveled on 258watt-hours of energy.

2.3watt-hours per mile... Extremely impressive for a motor cycle, and no pedal input options. LOL!


This bike stores the energy of an out-of-shape person pedaling in a relaxed manor for an hour. If you're going to get 3 hours of motorcycle transportation out of that effort, it's EXTREMELY impressive. Or an obvious impossibility.

OK, it's highly exaggerated. Nice to see the actual math on it.

On the plus side, your "battery" could last for hundreds of years and can "charge" and "discharge" rapidly. On the down side, your "battery charger" would be extremely large, heavy and expensive, possibly more than the cost of the motorcycle.

 

[TylerDurden]

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