The first known air turbine was made in Alexandria 150 years before our era. It consisted of a large vertical tube which by the draught it created, spun a propeller on which revolved pictures from mythology.
Not until last century with the development of aviation was any interest shown in air turbines or exhaust gases as a supercharge for engines. More than its known performance, it was its use in lack of air at high altitude that led to the use of the compressor in the First World War. It was a Frenchman Auguste Rateau who, in 1916 suggested the fitting of compressors as a supercharge. Two methods were used : to combine the compressor with the motor or to use the exhaust gases passed through a turbine. The first method: that of coupling the compressor to the motor was soon abandoned since at a certain altitude the power used by the compressor was greater than it produced. The second method, the turbo compressor, using energy from the exhaust gave greater force.
Of all the aircraft fitted with a supercharge of this nature, two are worthy of note. They were engaged in a dog-fight at 44,000 feet, a record altitude. One was a Junkers 86 fitted with a German heavy oil two-stroke diesel and a compressor attached, piloted by Horst Götz, (of whom more later as pilot of the Arado 234).
He was intercepted over Christchurch on his way to bomb Cardiff. His adversary in a Spitfire with a Rolls-Royce carburetor engine fitted with compressor was an Ace pilot of the RAF : Prince Emmanuel Galitzine, a descendant of Catherine the Great of Russia. They met at 44 000 feet in the first dog fight ever at that altitude, in a rarefied atmosphere for men and motors alike.
The engagement lasted 45 minutes without either gaining advantage. Horst Götz returned to Caen-Carpiquet worn out. It was an engagement that remains without parallel in air warfare of the Second World War.
After Mario Pezzi in 1939, they demonstrated that high altitudes were accessible to men and machines.
It may be noted in passing that Diesel aviation motors of the time were more powerful in relation to their weight than those fuelled by petrol. This perhaps explains why there is renewed interest today in diesel motors for light aircraft.
The turbo-compressor is now used on many vehicles and recycles exhaust gases. It was first introduced by Saab for lorries in 1967, though it was Renault who won the French Grand Prix in 1979 with a Formula One driven by Jabouille, that put the turbo-compressor in vogue for cars.
© Aérostories, 2000.