Talk:Air engine

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Could someone with knowledge of air cars please edit this page and take out the parts that sound like an ad? For example, not every air car has carbon fiber tanks(the MDI does). This page should be as impartial as possible, MDI technologies should move this info their own wiki if they want to highlight the features of their particular model. Also there appears to be a little bit of a problem with the language used to describe the two competing engine designs, as if someone representing Armando wanted to discredit MDI.

I think there is real promise in this field and that it is going to take off. The Australian engine is showing a really advanced design link here:Australian Air Car Video

This currently reads a bit like an ad for the air engine: can we have comparisons with petrol engines and other proposed replacement technologies such as fuel cell cars, batteries, flywheel storage? (Weight, cost, range, etc.)

I agree, from the artical it sounds like there is only one player in the game rather than giving a balanced view. Back ache 19:12, 24 July 2006 (UTC)

What about the explosion risk? What happens to the compressed air tank in a crash? Is it safer or riskier than a petrol tank? The Anome

Safety is always a concern, in the french design in an impact the carbon fibre tank rips in a controlled manor, the tank is an off the shelf item made by anopther company for storing LPG in vehciles so comes be used by other companys as well Back ache 19:10, 24 July 2006 (UTC)

There is this [1] which seems to be significantly diferent from regular engines in several aspects

TiagoTiago 18:31, 14 June 2006 (UTC)

If purists allowed a minor compromise...Air Car Hybrid. By adding a small, light weight, two-cylinder, fine tuned for constant speed, ultra low polluting engine, to drive a small, light weight, air compressor, the air could be recharged, slowly, any time, as needed. For initial concept-tests, only, a very small motorcycle engine could be used. It may not increase the range much but, while at the store or at work, or overnight, it could recharge itself and really improve the range. The design range goal should be a modest one, around 400 miles, including 1-2 hours without driving, while at lunch or client visits. At home, a cheap, small electric air compressor could be used overnight. --[Mike]

Isn't the air car just a hoax? /boivie

Not far off it, in my opinion the aircar is primarily a device for fleecing investors. The predicted range on the aircar website is something like 200 km, extrapolated up from an actual test run of 7 km (from memory). This entire article seems to take the inventor's word for its performance, it should be much more critical. Greglocock 02:48, 7 August 2006 (UTC)
May be the engine cools down after 7 km and looses its efficiency. Extrapolation is not reliable. --Fault-finder 09:55, 10 August 2006 (UTC)

I doubt it I'm a mechanical engineering student and my current group project, that's been given to all the students in my year, is to design and build a basic piston type air motor. BobBobtheBob

Fixed some typos in the applications section, but I have to say this is somewhat futuristic, not very informative for an encyclopedia article. - Yosef

Broke hippies?[edit]

Is that paragraph really supposed to be in there? If so, I think it could probably be re-written to be a little more neutral or academic in tone. Madmaxmarchhare 07:01, 1 July 2006 (UTC)

Questionable Overall Energy Efficiency[edit]

Looks like this discussion has bypassed the primary problem with the air car, which would be "system energy efficiency". It is stated in the end of the article that "low cost airlines could use the air engine to bypass high fuel costs". This is rubbish, as pressurized air cannot be mined from the ground, it has to be created using a primary energy source. A primary energy source would be fossil fuels, water power, solar power etc. The pressurized air only acts as an energy carrier.Currently something like 70% of the worlds electricity is produced from burning oil/gas, the rest from nuclear, coal and water power. The electricity used to run the air compressor will consequently have been made from the burning of fossil fuels, and burning the fossil fuel directly in the aircraft engine is likely to be both cheap and energy efficient. If you should be in possesion of a solar power plant you'll reduce the overall consumption of oil by using the electricity directly and thus reducing the need to burn oil to make electricity, and use the oil to power your car. Then the big question becomes how the air engine will compare with other energy carriers such as batteries or for instance hydrogen (you can use electric power to make hydrogen, then burn the hydrogen in a combustion engine or a fuel cell)

From a quick view of the technology it seems compressed air compares infavourably with the alternatives. When air is compressed large quantities of heat is created. This heat will normally have to be dissipated, meaning significant quantities of heat will be lost unless the heat can be employed usefully. It sounds very likely that a battery system will be more efficient in storing the energy than compressed air, even though there are also significant losses when charging and decharging a battery.

Furthermore, a piston engine sounds considerably more expensive to build and use (maintenance) compared to an electrical motor. (this is definitely the case for a combustion engine with transmissions).

I've added some figures on energy density and efficency (from my own calculations, still needs some reference) and also removed the section "... for other vehicles" because it simply isn't possible to fly airplanes with compressed air for any useful amount of time, and the model aircraft availble use CO2 rather than air. --Theosch 13:36, 27 January 2007 (UTC)


The paragraph about engine design does not look very neutral to me. It seems to take a sided view on a dispute between two inventors. [unsigned]

I think the whole article is a bit rough, both in language and in facts, but it seems neutral enough to me. I suggest removing the neutrality tag and perhaps replacing with a cleanup tag. --Theosch 17:56, 28 January 2007 (UTC)

IMPORTANT NOTICE! I feel that it is only fair that I post this amendment to the matter that I had posted earlier, after working on the problem for some time, I have come to the following conclusion. The MDI air car is NOT a scam. It does work, every bit of data supplied at the MDI air car web-site IS TRUE. The car does work as stated. A 320 litre tank filled with compressed air at 4200 psi (300 bars) WILL power the car with a performance equivalent to that of a car with an IC piston engine of 1 litre capacity, for 7 – 8 Hours. The tank CAN be refilled at home using a 4KW compressor in 3 – 4 hours. The end conclusion is that the car is no more dangerous than carrying around a couple of filled scuba tanks in the boot! DDjames 05:46, 20 October 2007 (UTC)


I agree. The language used is somewhat elementary. The article could use a cleanup. -- Gradyhillhouse 05:59, 27 May 2007 (UTC)

Agreed again, this article has a LOT of bias about the authenticity of the air engine and how it works. The television show Beyond Tomorrow did a segment on two air engines and found (and demonstrated/showed them working). You can view the clip yourself on YouTube [2]. They also discuss safety concerns with the tanks, they mention they crack/split instead of blow-up, making them very safety oriented in a collision. Therefor I'd like to make a motion to re-edit the "Safety" section of the article to include this very critical point. As the article currently stands it is very misleading in nay-saying air-engine technology. Even though Tata motors in India has licensed this technology and will be selling over 6,000 "air-cars" in August 2009 [3]... and remember, thousands of powerplants are MUCH easier to regulate than MILLIONS of cars. The "factory tailpipe" is a mute point. -- Goney3 23:39, 31 July 2007 (UTC)

Section 2 and thoughts on the 'zero pollution claim'[edit]

Section 2: Engine Design starts like this: "It uses the expansion of compressed air to drive the pistons in a modified piston engine." Which engine is being talked about. As noted in section 1, there is more than one type.

Also, if you are going to mention that to compress the air the car runs on costs electricity, provided by an electrical power plant that usually runs on coal or gas, you could also mention that that is still a huge improvement:

  • A car that runs on fossil fuels can never be zero pollution, an air car *could* be (depending on how energy used to compress the air is generated)
  • We are currently talking about energy plants generating electricity and then using that electricity to power air compressors. However, you might be able to use a power source such as water turbines to compress air directly from kinetic energy, skipping transformation to and from electricity.
  • It happens that more energy is being pumped onto the power grid than is being consumed. At such a moments the grid current would get disturbed, making it necessary to turn off/down some energy sources. This poses problems for wind turbines, because they deliver very variable and unpredictable amounts of energy. If many cars would run on compressed air, you could use excess power at such moments to compress air and pump it into an air distribution grid. It could then be used for refueling at a later moment.
  • There are all kinds of schemes being developed to make even coal powered power plants environmentally friendly by catching the CO2 that the power plant emits and storing it somewhere or letting it be converted to other forms. There are several experiments running to store the CO2 in near-empty gas fields for example. All these kind of plans can obviously not be applied to the CO2 emission from individual car engines, but they might be viable for power plants.
  • It's much easier to combat the pollution of just a few power plants than of millions of cars. Also, power plants are usually built somewhere near, but not *in* the city. So even if globally there is no benefit, at least locally the pollution could be moved outside of city centers and residential areas. Smog is a serious problem and this engine technology could solve it.

-OddesE —Preceding unsigned comment added by (talk) 18:08, August 24, 2007 (UTC)

I am surprised that the question of exactly how long the compressesd air in the tank will last, has not been studied in more detail. Ok, suppose that you have a piston cylinder with a volume of 8 cu ins. And the size of your air tank would be about, should we say 4ft x 2ft x 3ft. or 24 cu ft. Now in an engine running at 3600 rpm, which is around a mid range rpm, the engine would 'fire' 60 times a second using, 480 cu ins of compressed air and in 1 minute it would use 28,800 cu ins. Thus even w such a huge tank of 41,472 cu ins capacity would last less than a minute or around 1.44 minutes!! How far would you expect the car to go in that time. And you can forget about using a small cute compressor to refill the tank as it gets used. Compressing air is very much like generating electricty, the more wattage (psi) you compress the more power that is needed. So the whole idea of an engine is a total scam. A much better idea for a truly fuel, efficient, clean and powerful car engine is the Rotary Pulse Jet Engine. One further point that I would like to add is on the question of safety of the air engine. Air craft tyres were originally tested for bursting stress, at the Dunlop factory in England,by filling the tyres with compressed air. The tyres burst after being filled with just 500 psi of air, and when the tyre burst the whole of the testing facility was demolished with it! Nowadays water is used instead of air for testing critical pressure limits of air craft tyres. Think of 3000 psi going up! DDjames 14:31, 8 September 2007 (UTC)

DDjames, you forgot pressure. They have a 200 liter tank at 200 bar, which is about 200 atmospheres. This means that they have 200 times the volume of the tank (or 40,000 liters of air) once expanded to standard pressure. Your example at 200 bar (4800 cu ft) would run for hours. I think they minimize thermal issues as well as other efficiency losses, so the actual running time would be much shorter. Bcwaller (talk) 00:01, 12 January 2008 (UTC)

Can we have a simple explanation in English?[edit]

The main text in the article does not explain how the engines work in a manner that is comprehensible to the average encyclopaedia reader. Much of the text is obviously written by people for whom English is not a first language.

In a quick search of the internet I cannot find one article that truly explains how the various air engines work. None that I have seen mention the capacity of the engine cylinders or the RPM operating range of the engines! None really looks at the issue of how long a charge of compressed air will last to operate the engine. One video looks remakably like a fanciful perpetual motion engine. Some of the websites are full of gobbledegook that looks suspiciously like it is meant to "baffle brains with bullshit" rather than to truly explain the mechanism. The internet and Wikipedia have simple explanations of how an internal combustion engine, a steam engine, a gas turbine, or an electric motor works. Surely, the same can be done for the air engine unless of course explaining it fully will detract from investor confidence.

--CloudSurfer 20:28, 2 December 2007 (UTC)

I agree with CloudSurfer, and an encyclopedia should also contain pictures and graphics wherever available and useful. Why is the only mentioned option 'refueling' which seems to be a problem, why can't the tanks not be designed for a quick and easy exchange of pre-filled tanks, maybe even two or several smaller tanks giving more flexibility. (I would not consider to refill a bottle of beer at refilling stations all over the country, I buy a new one) that would be a big chance for this new technology. Scyriacus (talk) 09:19, 11 January 2008 (UTC)

That would be nice. Unfortunately there can be no clear believable explanation, because the various machines that are being discussed are mostly hucksters' props. Unfortunately there are no reliable sources that really discuss the physics of the machines, so we are left with PR, marketing, and lies repeated by unsceptical journalists. Greg Locock (talk) 09:50, 11 January 2008 (UTC)

Too many articles[edit]

We have compressed air vehicle, air engine, air car and I don't know how many others, all with the same content, and none of them stunning examples of Wikischolarship. Merge the lot I say. --Wtshymanski (talk) 16:15, 6 January 2008 (UTC)

I just did some back of the envelope calculations since the claims seem so amazing.

They took a 7.22 km test run and "proved" that the production car would go 191.10 km, and further developments would take it to 242.10 km on a single charge. See, you get a 1.96x boost from mass reduction, and then another 3.90x boost from more usable air volume, times another 2.51x factor from "Classic distribution seal with reduced friction due to use of rollers" and then an extra 1.38 multiplier for a three stage isothermic expansion. And Bam, you have 191.10 km range!

Then they say you can take that and possibly increase air pressure and volume even more and the range is up to 242.10 km. I checked their math and they got it wrong anyhow. It should really end up at 267.36 km.

If I had to take a guess, I'd RSS the factors for a gain of maybe 5.5x, and a range of up to 40 km.

I checked on energy density as well. I found a reference that said that 5 liters of air at 200 bar gives about 330 kJ of usable energy. This car has a 200 liter tank, which results in 13.2 mJ of energy. A gallon of gas has 131 mJ of energy, and if converted at 20% efficiency (I think the best engines are over that, maybe as high as 30%) that one gallon has 26.2 mJ of energy.

I'd guess that the range would be about the same as a similar sized car with a tiny engine and a gallon of gas, at most. I stand by my 40 km guessed at above. Bcwaller (talk) 23:48, 11 January 2008 (UTC)