An Engineering Challenge - The A-Bike!

[musicbooks]

I watched with interest on the news last night the story of the compressed air car. Well, that got me thinking. There are quite a few engineers who contribute to this forum. Do you think it possible to convert the system to work on an e-bike.. ? Or should that be an A-Bike! ..

I'd better not try ( I'm too full of hot air as it is! )

BW
musicbooks

 

[flecc]

Tank weight could be a problem on a bike, and also there's be no enveloping protection for the tank or pressure lines to cope with containment failures.

On a two wheeler it would need to be a moped (scooter) rather than a bike I think.
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[Ian]

Don't forget the exemption from motor vehicle legislation that we enjoy applies specificly to "bicycles with an auxilliary electric motor", so under existing legislation an air powered machine would be considered a motor vehicle. The air tank would also come within the scope of the stringent regulations and insurance requirements concerning pressure vessels.

So while it's possible it would be unlikely to be worth the considerable hassle involved.

For anyone determined enough air power tools are cheap enough and contain a tiny but powerful air turbine and reduction gear that could be used as the basis for a motor, and a divers SCUBA tank is a ready made tested and certified air tank.

Compressed air power is not a new idea, it was first used well over 100 years ago to power amongst other things mining locomotives where a low fire risk power source was needed before the advent of safe portable electricity. The only problem was that the air tanks themselves were prone to explosion in the days before proper inspection and testing!

 

[musicbooks]

Don't forget the exemption from motor vehicle legislation that we enjoy applies specificly to "bicycles with an auxilliary electric motor", so under existing legislation an air powered machine would be considered a motor vehicle. The air tank would also come within the scope of the stringent regulations and insurance requirements concerning pressure vessels.

So while it's possible it would be unlikely to be worth the considerable hassle involved.

For anyone determined enough air power tools are cheap enough and contain a tiny but powerful air turbine and reduction gear that could be used as the basis for a motor, and a divers SCUBA tank is a ready made tested and certified air tank.

Compressed air power is not a new idea, it was first used well over 100 years ago to power amongst other things mining locomotives where a low fire risk power source was needed before the advent of safe portable electricity. The only problem was that the air tanks themselves were prone to explosion in the days before proper inspection and testing!

Sounds more like an A-Bomb than an A-Bike

 

[richard]

I wonder what pressure the storage tank is pumped up to, and also what sort of pump you would need.
richard

 

[Ian]

Sounds more like an A-Bomb than an A-Bike

More true than you may think.. look here.

Scuba Tank Safety - The Scuba Guide

 

[Ian]

I wonder what pressure the storage tank is pumped up to, and also what sort of pump you would need.
richard

The old mining locomotives used a very large tank pumped up to relatively low pressure of probably about 150 psi. A lighter more compact modern solution would need a smaller tank but at a very much higher pressure to store a useful amount of energy. A SCUBA tank pumped up to its typical rated pressure of 190 bar or 2700 psi would probably power a 200W motor for an hour or two.

Because SCUBA tanks are widely used suitable compressors are readily available. They are complex machines that usually have 3 separate stages, that being the only way to achieve such a high pressure.

 

[richard]

Thank you Ian, going on from aquisition and storage what sort of motor would an air propulsion unit require.
I must admit I am quite fascinated.
Richard

 

[coops]

When I read A-bike I thought this thread was about Sir Clive Sinclair's folding A-bike which would be an engineering challenge to ride by the looks of it!

I also saw the news item musicbooks & watched it with interest, though the reporter's comments on driving a prototype didn't sound promising - "it sounds like a motor boat & handles like a bread van!" - they hope to iron out any problems before release... though the car appears to have been many years in the making already.

The concept & application to bikes was discussed in some detail in another recent thread, Forget Electric, use air so more information there .

Stuart.

 

[Ian]

Thank you Ian, going on from aquisition and storage what sort of motor would an air propulsion unit require.
I must admit I am quite fascinated.
Richard

I'm by no means an expert on air propulsion but most of the motors I know of are either air turbines which work on a similar principle to a tiny windmill.. in a hurricane! or vane motors, the principal of which is shown here. Clicking on the picture should launch an animation demonstrating the operation. This is actually a compressor, the motor is similar but in reverse. This is a picture of the innards of a small air turbine, despite its tiny size it can deliver over 50 watts at 130,000 rpm! and this is a much larger air turbine for use as a starter motor for an industrial gas turbine. The diameter is only 6" and the weight 12kg yet it delivers an astonishing 124kW.

I would guess that the air car uses a piston engine, rather like a traditional steam engine judging from Stuarts description of the reporters comment "sounds like a motor boat". This will be larger and heavier but possibly more efficient than the above types.

The major drawback of air propulsion has to be the poor overall efficiency. Neither air compressors or air motors are particularly efficient and the combined efficiency will inevitably be poor. Having said that, if a green energy source were used to power the compressor it could have environmental benefits.

 

[flecc]

When I read A-bike I thought this thread was about Sir Clive Sinclair's folding A-bike which would be an engineering challenge to ride by the looks of it!

The real challenge with Clive's A bike would be to turn into an e-A bike.
.