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Posted
13 hours ago, onetrack said:

But you have to input a serious amount of energy to compress the gas, Spacey. There have been experiments using compressed air for motive power, but it's not a viable system over anything more than a short distance.

 

For machines or vehicles or equipment working over short distances in say, factories or other short-distance operations, it can work. The lack of fumes is a big factor.

 

However, even lead-acid batteries and electric motive power, are probably more efficient.

In fact, I think it was Peugeot that was experimenting with compressed air for a hybrid. Compressing air during braking. I was very excited about the idea, because it's much simpler than batteries. Unfortunately, as you say, huge inefficiencies compressing the air. They dropped the idea.

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Posted

Air compressors are not that inefficient if they are made well.. Universal gas laws prevail. Heat energy can be lost in most set ups. Some planes were users of compressed air for brakes, steering and U/C extension. retraction. 3600psi 4 stage air  compressor (Dunlop)in the  F 27.  Nev

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Posted
25 minutes ago, facthunter said:

Air compressors are not that inefficient if they are made well.. Universal gas laws prevail. Heat energy can be lost in most set ups. Some planes were users of compressed air for brakes, steering and U/C extension. retraction. 3600psi 4 stage air  compressor (Dunlop)in the  F 27.  Nev

They won't tolerate a dirty filter element, would need to keep very clean to maintain efficiency.

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Posted

I remember some talk about massive rotating discs storing potential energy for stationary devices such as ski lifts and funiculars but seems to have gone quiet lately.

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Posted

There were some buses that used big flywheels for part of their energy inputs, in Europe and in Africa, in the 1950's, but they were ultimately unsuccessful.

 

https://en.wikipedia.org/wiki/Gyrobus

 

I seem to recall there were further experiments done with buses using flywheels operating in a vacuum in a sealed compartment, but ultimately, this idea was not proceeded with, either.

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Posted

It wouldn't want to come loose or seize up.  Pneumatic pressure brings the gear UP FAST and helps the  climb gradient achieved.  Nev

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Posted (edited)

Facthunter, how did Fokker get around the major issue of moisture, and subsequent corrosion in the F27 pneumatic system? They must have had some type of exceptionally-effective air-drier?

 

In mining, pneumatic systems are used a lot, to operate air rams that open and close ore chute doors, and other actuation devices. They're a PIA to work with, with corrosion being a major problem, despite air driers being used.

 

Edited by onetrack
Posted

Dunlop bult the Pump and I only  experienced one  (Partilal) failure and never heard of any others. It's a 4 stage pump to 3600 Psi. . Air brakes on a Plane are a bastard to use. They had antiskid called "Maxaret"   Nev

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Posted
On 31/03/2025 at 3:00 PM, facthunter said:

Air compressors are not that inefficient if they are made well.. Universal gas laws prevail. Heat energy can be lost in most set ups. Some planes were users of compressed air for brakes, steering and U/C extension. retraction. 3600psi 4 stage air  compressor (Dunlop)in the  F 27.  Nev

Unfortunately there's a two way loss that is hard to get around - compressing the air generates lots of heat. Decompressing it, eg driving a piston engine, absorbs lots of heat, potentially freezing up the engine. This was definitely a problem with the model CO2 motors I used. You would actually get ice on the pipes!

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Posted
1 hour ago, Freizeitpilot said:

https://www.aero-expo.com/conferences/hydrogen-and-battery-summit#1

 

Aero Friedrichshafen is the largest GA exhibition in Europe. This accompanying conference will provide an insight into the current European thinking for non fossil fuel flight. The presentation on a hydrogen powered 916is engine should be interesting.

 

This will be a bit of an eye opener for those knockers of nitrogen power. I think you'll see it take off in the not too distant future. I'd love to be there but I'll be leaving for the 1200km trip south to Esperance to continue and hopefully complete my flying lessons.

Posted (edited)

OOOPS

Not a lot of Nitrogen engines anywhere 

But they Are safe ! .

Spacesailor

 

PS. : Liquid nitrogen is easier to transport !.

Even my doctors have a can of it , to freeze bits off your body  .

Edited by spacesailor
PS & Spelling
Posted

Nitrogen to all intents and purposes is INERT. It only combines at extremely high temps, which is fortunate as it is 78% of the earth's atmosphere. Nev

  • Agree 1
Posted

Nitrogen is an element.  Early in  chemistry you learn about elements, mixtures and compounds, Acids and Bases Metals and non  metals.  Nev

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Posted

 Ammonia is a safe source of Hydrogen. NH4 I still cannot understand what a Nitrogen engine is?  Nev

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Posted (edited)
3 hours ago, facthunter said:

 Ammonia is a safe source of Hydrogen. NH4 I still cannot understand what a Nitrogen engine is?  Nev

You've compelled me to look it up. Seems it's a variation on a compressed air motor, but using liquid nitrogen that is heated to become pressurised gas 

 

https://en.wikipedia.org/wiki/Liquid_nitrogen_engine

 

As far as I can tell, this is the only car to have used a liquid nitrogen engine 

images (31).jpeg

Edited by danny_galaga
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