Compressed air propulsion

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veloman   1 GW

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Compressed air propulsion

Post by veloman » Oct 22 2013 5:35pm

http://nuaira.com/

It says 300watts output. I asked how many watt hours.

I wonder about the price, compared to a low power e-assist.
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wineboyrider   100 MW

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Re: Compressed air propulsion

Post by wineboyrider » Oct 22 2013 5:38pm

Wonder how big the air tank is....LOL
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veloman   1 GW

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Re: Compressed air propulsion

Post by veloman » Oct 22 2013 5:46pm

Yeah, it's 4500 psi. Perhaps a few inches from your family jewels? It's carbon fiber.
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Re: Compressed air propulsion

Post by rogerc » Oct 22 2013 10:41pm

Biggest problem I can see is the noise coming from the actual release of compressed air into the hub.
I really like quiet ebikes and the stealth mode.
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dogman dan   100 GW

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Re: Compressed air propulsion

Post by dogman dan » Oct 23 2013 6:26am

Only thing like it I ever saw, did have some noise with it. Sounded surprisingly like a regular put put of a gas engine, but with no smog emitted.

This was on a car platform, and the touted use was inner city delivery like food or messenger packets. The benefit over electric was quick recharging compared to a battery.

But taken to bike size, it's not so hard to swap batteries. You do of course have the cost of extra packs though. A home based compressor to that psi won't be dirt cheap though.

I just don't see it being enough better than todays ebikes.

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Re: Compressed air propulsion

Post by Ykick » Oct 23 2013 6:50am

I didn't read all the details but if it's reclaiming energy from coasting/braking to be used later for a small boost I suppose it could be useful in some contexts? Very little added weight and the tank is from paintball guns which people hold next to their faces.

Of course it's not gonna be comparable to 1kWh of battery and motor but for what they intended it's probably very little added weight to haul around for an occasional boost.
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EldRick   10 mW

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Re: Compressed air propulsion

Post by EldRick » Oct 23 2013 1:48pm

...it's probably very little added weight to haul around...
Except for the scuba-diving tank on your back...
:lol:

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Ykick   100 GW

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Re: Compressed air propulsion

Post by Ykick » Oct 23 2013 2:47pm

EldRick wrote:
...it's probably very little added weight to haul around...
Except for the scuba-diving tank on your back...
:lol:
The compressed air tank, which is made of carbon fiber and was originally designed for paintball guns, fits into the bike’s water bottle holder.
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MadRhino   100 GW

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Re: Compressed air propulsion

Post by MadRhino » Oct 23 2013 5:43pm

Ykick wrote:
EldRick wrote:
...it's probably very little added weight to haul around...
Except for the scuba-diving tank on your back...
:lol:
The compressed air tank, which is made of carbon fiber and was originally designed for paintball guns, fits into the bike’s water bottle holder.
...and will bring you as far as a paint ball firing range if you expect any performance of it. :mrgreen:
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liveforphysics   100 GW

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Re: Compressed air propulsion

Post by liveforphysics » Oct 23 2013 6:01pm

I did some searching on paintball tanks, looks like 90in^3 (1.47L) is the largest volume I could find.

At 4,500psi, that tank is packing ~228kJ of energy, or 228,000watt-seconds of energy.

In watt hours, that's just 63Wh.

Roughly the same energy in a standard 6-cell laptop battery, or a bit less energy than 6 of my cell phone battery holds.
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Re: Compressed air propulsion

Post by teklektik » Oct 23 2013 6:14pm

Air Powered Scooter.... from 2008
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pdf   10 kW

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Re: Compressed air propulsion

Post by pdf » Oct 23 2013 7:13pm

liveforphysics wrote:I did some searching on paintball tanks, looks like 90in^3 (1.47L) is the largest volume I could find.

At 4,500psi, that tank is packing ~228kJ of energy, or 228,000watt-seconds of energy.

In watt hours, that's just 63Wh.

Roughly the same energy in a standard 6-cell laptop battery, or a bit less energy than 6 of my cell phone battery holds.
And you will never get near that much energy out of it, that is the best case scenario, isothermal. When you start expanding air from 4500 psi to 14.7 psi, it is going to cool way down. I don't know what the efficiency is but maybe half that? Depends on rate of energy extraction. So strap on 10 of those 1.4 liter tanks to get to the store and back and then let's talk fugly. My opinion? It will never see the light of day. Ask him how much that carbon fiber tank costs; about as much as a battery with 8 times the capacity.
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liveforphysics   100 GW

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Re: Compressed air propulsion

Post by liveforphysics » Oct 23 2013 7:54pm

pdf wrote:
liveforphysics wrote:I did some searching on paintball tanks, looks like 90in^3 (1.47L) is the largest volume I could find.

At 4,500psi, that tank is packing ~228kJ of energy, or 228,000watt-seconds of energy.

In watt hours, that's just 63Wh.

Roughly the same energy in a standard 6-cell laptop battery, or a bit less energy than 6 of my cell phone battery holds.
And you will never get near that much energy out of it, that is the best case scenario, isothermal. When you start expanding air from 4500 psi to 14.7 psi, it is going to cool way down. I don't know what the efficiency is but maybe half that? Depends on rate of energy extraction. So strap on 10 of those 1.4 liter tanks to get to the store and back and then let's talk fugly. My opinion? It will never see the light of day. Ask him how much that carbon fiber tank costs; about as much as a battery with 8 times the capacity.

Yes, fully agreed. That value is simply the potential energy stored in the tank. You can't make use of that energy efficiently without sipping it at a very low rate, and even then it's still quite lossy.

Compressed air vehicles may rival ICE's for who can waste the most energy. They waste a ton of energy in the compressor to fill them, then again when being used (smaller the tank for a given power rate, the higher the loss).

Somebody should show the compressed air vehicle building guys batteries. Chargers at >94% efficiency, battery charge efficiency at >99%, and energy stored per unit volume/mass an of magnitude better than compressed air. It's difficult for me to understand how/why anyone who works the math out would bother.
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flathill   100 kW

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Re: Compressed air propulsion

Post by flathill » Oct 23 2013 9:29pm

Video or it is a scam

It could be about half the specific energy density of lead acid
Which is not horrible if the motor makes a ton or torque somehow
Most bldc hub motors are not efficient at low speed
The air motor could be good for taking off and hills
The only place you really need a motor on a bike unless you are disabled/old/fat/blah
Or just really want a motorcyle

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Ykick   100 GW

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Re: Compressed air propulsion

Post by Ykick » Oct 23 2013 10:32pm

Of course it makes no sense for pumping-up at home and riding off WOT. The energy conversion is simply too wasteful and meaningful storage capacity too bulky.

I dislike the "secret squirrel" nonsense and references to "magic" of the website but IF it does implement regen air pressure back into the tank from coasting and/or braking the idea can possibly serve a usefulness for a very small amount of occasional assistance with minimal weight penalty.
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