Pneumatic Vehicles?

[Tallor]

I was looking through some creative ideas for propulsion, both land and sea, and discovered some attempts at making vehicles that turn their turbines or wheels using compressed air. However, I don't think compressed air methods are in the 3e Vehicles books. Maybe the expansions but I'm not sure.

Does anyone have any ideas on some possible weights/costs for pneumatic engines?

[clu2415]

That sounds like it's a different form of transmission. Instead of a mechanical linkage transferring power, you are compressing air and sending power that way. It would conceivably let you do away with axles the same as having an electric motor for each wheel would.

[RyanW]

Originally Posted by clu2415

That sounds like it's a different form of transmission. Instead of a mechanical linkage transferring power, you are compressing air and sending power that way. It would conceivably let you do away with axles the same as having an electric motor for each wheel would.

You could also use a pressure cylinder as a "battery" and skip the engine, or even make a hybrid.

[Fred Brackin]

Originally Posted by Tallor

I was looking through some creative ideas for propulsion, both land and sea, and discovered some attempts at making vehicles that turn their turbines or wheels using compressed air. However, I don't think compressed air methods are in the 3e Vehicles books. Maybe the expansions but I'm not sure.

Does anyone have any ideas on some possible weights/costs for pneumatic engines?

WWI and most WWII torpedoes were powered by compressed air. That's why they made those wakes full of bubbles. These were largely replaced by battery electric systems and modern torpedoes get far more range.

So you've got a system that can give you about as much output as a TL6 electric system but possibly even less endurance.

If you want Ve2 compatible stats for compressed gas cylinders as a means of storing energy you need to go to Gurps; Steam-tech p.44.

[Tallor]

Originally Posted by Fred Brackin

WWI and most WWII torpedoes were powered by compressed air. That's why they made those wakes full of bubbles. These were largely replaced by battery electric systems and modern torpedoes get far more range.

So you've got a system that can give you about as much output as a TL6 electric system but possibly even less endurance.

If you want Ve2 compatible stats for compressed gas cylinders as a means of storing energy you need to go to Gurps; Steam-tech p.44.

Ahh, okay. So it's an energy bank, but... pneumatic, I suppose the term would be. Thanks! :D

[dcarson]

History article on compressed air powered locomotives for mines where you need to worry about dust explosions. http://www.douglas-self.com/MUSEUM/L...co/airloco.htm
Replaced by battery power quite a while ago. Another one I found was talking about an attempt to introduce a compressed air scooter in India. Has 12% of the energy storage per volume of batteries, 1% of gasoline. Since India has mainly coal power plants to higher pollution and less efficiency means it actually produces twice the C)2 of gasoline engines just at a remove.

[whswhs]

Originally Posted by Tallor

Ahh, okay. So it's an energy bank, but... pneumatic, I suppose the term would be. Thanks! :D

You actually can have compressed air transmission lines, too. They were experimented with between the invention of steam power and the commercialization of electric power. I researched them for GURPS Steampunk (the original one back in 2000). I don't remember all the details, but they lost a higher percentage of power per mile of distance, making them unsuitable for power networks. But within a single building you could have pipes carrying air, or water, or steam and extract work from the pressure.

[The_Ryujin]

Originally Posted by Tallor

Ahh, okay. So it's an energy bank, but... pneumatic, I suppose the term would be. Thanks! :D

It's been a while since I've looked into this but from what I remembered they held only about 12% of the energy per pound compared to a TL6 battery but had a much higher wattage then even modern batteries (I don't think I ever found a specific figure though). GURPS Vehicles only looks at the kilowatt hours a battery can hold and ignores wattage so it would be hard to find a use for a pneumatic storage system using Vehicles rules.

[Anthony]

The theoretical cap on compressed air is equal to the total thermal energy of the stored air, less the amount that is still in the air when it escapes, plus anything that can be recovered by absorbing heat from other components of the engine (air escaping from a pressure chamber cools off substantially). This is... not very much (about 0.5% of what you get from burning an equivalent weight of gasoline).

[johndallman]

You can get substantially more energy from a compressed air engine if you have some way of heating the air. This was normal for compressed-air torpedoes, since the very cold expanded air tended to freeze seawater.

The usual method was to burn a liquid fuel, either alcohol or petroleum, in the plentiful supply of air. A more advanced form of this would use more fuel and boil seawater for steam. Steam torpedoes had significantly better speed and range than ones powered by lead-acid batteries at TL6; I can dig out figures if anyone wants them. The advantages of electric torpedoes were the lack of wake, safety, and no alcohol for the sailors to get at.

Nowadays, electric torpedoes use much more advanced batteries, usually silver-zinc, and combustion torpedoes, such as the US Mark 48 ADCAP, use monofuels.