Every so often an established car company pretends it's going to put out an air car, and the ruse lasts long enough to keep the public confused, discourage inventors from trying to go into competition with them, and make air cars in general look like a "no go". A couple years ago, for example, a big car company came out with a fairytale concept involving flying windmills to operate compressor stations.
The rest of this page is about real air cars and/or real development projects; those with the best ideas, those who are trying the hardest and/or getting the most attention. There's a tendency for such projects to be the work of actual people who can't really afford to save the world from technology, rather than corporations that could if they wanted. But as part of my thesis that corporations are not people, I am going to suggest that corporations actually don't want anything except bigger profits; nothing else matters.
When I was going to libraries to do this research, I tried to collect every detail about every rumored air car. I did that for many years before there was an internet, and then one day when I got my first internet connection, I "infoseeked" air cars—this was before you could "google" air cars—and I got 15 hits. The only one I remember was about how to build an air car from PVC pipes. Now you get thousands of hits. I just now googled "air cars" along with my name, and got 80 hits. So things are changing and it would be pointless for me to reproduce all the current news and rumors about air cars by trying to summarize and repeat it all here.
However, I think it is more important than ever to have some idea where air cars came from, how they got started, became one of the most popular ideas, and how—and when—they got stopped. Not that I expect that condition to be permanent...unless we manage to stay out of the workshop for a few more years while the rest of our rights are taken away and the power structure is put into place for the eventual last petroleum reserves to be stockpiled for corporate use.
For half a century the air-powered locomotive was a serious contender for the top spot in transportation because of its obvious advantages: simplicity, safety, economy, and cleanliness. Air engines were built first during a period of experimental daily use in metropolitan street transit during the 1880s and 1890s, by companies organized by inventors and air car advocates such as General Herman Haupt. In New York City a building-sized 1500 horsepower compressing station was constructed for the use of the transit locomotives that were being tested there on daily routes. Air-powered mining locomotives were manufactured routinely by steam locomotive companies. Until the 1930s and 1940s the air mule had no serious competition from electric or internal combustion engines in mining because the heat and spark made them unsafe in closed-in and gassy places.
The term "air engine" disappeared from engineering textbooks between 1931 when William Lawrence Saunders died, and the end of the second world war. Gas engines had been perfected, the power of the oil industry was established, and gas was cheap. After Saunders' sudden death while he was on vacation, a new CEO of Ingersoll-Rand was chosen who was paranoid, secretive, wouldn't allow himself to be photographed, and turned in his annual financial report on a single sheet of paper folded in half. With certain key phrases and concepts no longer mentioned in textbooks, interest in air cars dwindled. Ingersoll-Rand's official publication as the largest compressed air corporation in the world, Compressed Air magazine, grew fashionably aloof from compressed air and almost never mentioned air cars. The oil glut was in full swing; nothing as simple as a better idea was going to stop that.
Serious interest in air cars was rekindled by the petroleum shortages of the 1970s. There are now hundreds of patented designs for conventional, hybrid, closed cycle, and free range air cars, as well as conversions for existing engines.
Similar to modern electric subway trains, the power supply was provided continuously by a pipeline laid along the track. This concept was not practical at the time it was invented (1820s) because the materials were not available to make it work reliably. A modern version appeared in Brazil in the 1980s, invented by Oskar H. W. Coester, and developed by Aeromovel Global Corp.
Preceding this was New York City's first attempt at a subway, in which a lightweight car fits more or less airtight in a wind tunnel and is blown along by very large fans from one end or the other of the tunnel. Slawomir Lotysz PhD wrote his doctoral thesis on the origins of air as a transport medium. His study covers developments worldwide in the pneumatic locomotives of the 19th century.
The Mekarski air engine was used for street transit. It was a single-stage engine (air expanded in one piston then exhausted) and represented an advance in air engine technology that made air cars feasible: the air was reheated after leaving the tank and before entering the engine. The reheater was a hot water tank through which the compressed air bubbled in direct contact with the water, picking up hot water vapor which improved the engine's range-between-fill-ups.
Robert Hardie's air engine was a going concern in street transit in New York City. Air car advocate General Herman Haupt, a civil engineer, wrote extensively about the advantages of air cars, using the Hardie engine on the job as his source material and providing much of the impetus for the New York experiment to gain support. The engine was a one-stage expansion engine using a more advanced type of reheating than the Mekarski engine. One of its new features was regenerative braking. By using the engine as a compressor during deceleration, air and heat were added to the tanks, increasing the range between fill-ups. Check valves were installed on the engine cylinders to admit atmosphere to the cylinder in case over-expansion of the compressed air produced a partial vacuum, allowing the engine to operate with full expansion. A 1500 horsepower steam-powered air compressor station was built in New York City to supply the Hardie compressed air locomotives as well as the Hoadley-Knight pneumatic locomotives.
The Hoadley-Knight system was the first air powered transit locomotive that used a two-stage engine. It was now recognized that the longer you keep the air in the engine, the more time it has to absorb the heat that increases its range between fill-ups. Hoadley and Knight were also supporters of Nikola Tesla's bladeless disc turbine, for which they formed a propulsion company.
Inventor Charles B. Hodges became the first and only air car inventor in history to see his invention become a commercial success. His engine was two-stage and employed an interheater between the two piston stages to warm the partially expanded compressed air with the surrounding atmosphere. A substantial gain in range between fill-ups was thus proven attainable with no cost for the extra energy, which was provided by the sun. The H. K. Porter Company in Pittsburgh sold hundreds of these locomotives to coal-mining companies in the eastern U.S. With the hopeful days of air powered street transit over, the compressed air locomotive was safely tucked away in coal mines around the world because it created no heat or spark and was therefore invaluable in gassy mines where explosions were always a danger with primitive electric or gas engines.
Charles B. Hodges' design was improved upon by European engineers who increased the number of expansion stages to three and used interheaters before all three stages. The coal mines of France, Belgium, Germany, and other countries were swarming with these locomotives, whose range between fill-ups was increased up to 60% by absorbing ambient heat. It might have become apparent to the powers-that-be that these upstarts were a threat to the petroleum monopoly that was taking over the transportation industry; after world war two the term quot;air engine" was never used in compressed air textbooks, and air powered locomotives, if used at all, were usually equipped with standard, inefficient air motors.
A European researcher told me that the three-stage design didn't work out to be as flexible as the two-stage. At the time that world war 2 came along and stopped the natural direction of industrial progress, the coal mine industry in Europe was preparing to go back to Hodges' original two-stages. Possibly the higher efficiencies were available under certain ideal conditions and the rest of the time the third stage was a drag on the first two. I have heard this theory about Terry Miller's 4-stage air engine from an engineer who tested one of Terry's air cars on a dynamometer.
In 1930, just before technical journals stopped reporting on compressed air locomotives, they carried stories on a 1200 horsepower full-size locomotive that had been developed in Germany. An on-board compressor was run by a diesel engine, and the air engine drove the locomotive's wheels. Waste heat from the diesel engine was transferred to the air engine where it became fuel again. By conserving heat in this way, the train's range between fill-ups was increased 26%.
Robert C. Burt PhD was a real physicist, a G.E. scientist with several basic patents of his own including photoelectric cells, hearing aids, and other things I can't spell. His patent is a good learning tool since it outlines some of the basic principles and formulas for compressing and expanding air. His compressor was driven by a 4-cylinder gas engine and the exhaust from the air engine was re-compressed, so it was both hybrid and closed-cycle. He also conserved heat for re-use by the air engine, so if he had replaced his gas engine with an electric motor like Bill Truitt did, he might have learned something they didn't teach him at Cornell! After many years in mothballs, the Burt Air Drive was hot to trot again in 1980, but for some reason the sure thing didn't happen.
In 1979, Terry Miller set out to design a spring-powered car and determined that compressed air, being a spring that doesn't break or wear out, was the perfect energy storage medium for an alternative car. From there he developed his Air Car One, which he built for $1500 and patented. He showed his air car from coast to coast and then went on to other things. In 1993 he picked up his air car project again with the help of Toby Butterfield of Joplin, Missouri. They developed the Spirit of Joplin air car with parts mostly donated by manufacturers. Terry's air engines demonstrated the feasibility of building air engines with off-the-shelf parts on a small budget. His engines used up to four consecutive stages to expand the same air over and over. They ran at a low speed so there was plenty of time for ambient heat to enter the system and the possibility of low-tech developers to build engines cheaply at home. Terry was instrumental in educating the founder of Pneumatic Options on air car fundamentals. Terry's greatest contribution—and what makes him an air car advocate, not just another inventor—was that he published and made easily available the complete details on how to build an engine like his. No other inventor has done this. Shortly before his death in 1997, Terry Miller gave all rights to his invention to his daughter and to Toby Butterfield. Mr. Butterfield died in 2002.
Since the early 1990s, a French inventor named Guy Negre has been building an organization to market his air car designs in several countries. A web search for air cars will turn up thousands of references to his company, Moteur Developpment International (MDI). Mr. Negre holds patents on his unique air engine in several countries. Along with other inventors like Armando Regusci, Angelo Di Pietro, Terry Miller and others, it is Guy Negre and his son Cyril Negre who have put air cars back on the map.
Dr. Marquand has taken the highly commendable step of incorporating heat pipes into his air engine design for the recovery of compression heat. He also plans to use regenerative braking. It is not clear whether his engine has been tested in a car yet. Professor Marquand is a scientist with a number of published research articles to his credit. For further information contact:
C. J. Marquand or H. R. Ditmore, Dept. of Technology & Design, Univ. of Westminster, 115 New Cavendish St., London W1M 8JS, Tel. 0170 911 5000.
Tsu-Chin Tsao is a distinguished professor of mechanical and aerospace engineering at UCLA. He has invented a camless gasoline engine that does not idle; it uses compressed air to start the car, and when the air is gone the engine runs on gasoline. During deceleration, braking energy operates a compressor to fill the air tank for the next start. This brings to mind Buckminster Fuller's reminder in his magnum opus Critical Path, wherein he tells us how many horses (as in horsepower) could be jumping up and down going nowhere for all the gasoline being pointlessly burned by cars sitting at red lights at any given time. We have nothing but admiration and respect for Professor Tsao's serious step in a perfectly good direction, and apparently Ford Motor Company is in agreement: they are working with Tsao's team to look into the viability of putting a pneumatic hybrid on the road to compete with the Toyota Prius and other electric hybrids. The pneumatic hybrid is expected to save 64% in city driving and 12% on the highway.
Everything I've heard about this air engine is positive. Many people have written asking me to report on it, but the best I can do till I ride in his air car is to show you a picture and a link. Based on what is said about the engine, I think it sounds like a great improvement in air engines, incorporating the advantages of piston engines as well as the advantages of rotary engines.
This sounds like what other people have wished they could invent. A lot of people are counting on Mr. Di Pietro to get an air car on the market.
In my correspondence with Mr. Regusci of Uruguay, I found him a sincere person and his design very appealing. His invention does away with the crankshaft, using sprockets and chains and freewheeling clutches, to turn a shaft. He has built bikes and small air cars of various descriptions and is very devoted to the cause. His website is now on Facebook. An associate who speaks Spanish has interviewed Armando Regusci. You can also see his video on YouTube.
When I first contacted Mr. Regusci many years ago, he was helping a university in Texas with their plans to build liquid nitrogen car.