A Decade of Jets
By PETER KING
TEN years ago, on May 15th. 1941, the first successful flight of a jet-propelled aircraft was made from Cranwell Aerodrome. The aircraft was known as the E28/39 Gloster-Whittle ; the name described the number and year of its specification. the company which built it. and the man who, more than any other individual, was responsible for its existence. It is often said that either the Germans or the Italians made the first successful jet flight—but the claim is not strictly accurate. On August 27th, 1939, a few days before war was declared, an aircraft designed by the Heinkel Company did actually take off, but its He.S.3 engine gave trouble, and the flights were abandoned until after 1941. Almost exactly a year later the Italian Caproni C.C.2 first flew from an airfield near Milan. However, the engine of the C.C.2 had a conventional piston-engine as the power source of the compressor, not a true turbine, and cannot be described as a turbo-jet aircraft.
But although the Gloster-Whittle made the first jet-propelled flight. Whittle cannot be said to have " invented " jet-propulsion ; the claim to that distinction goes back many centuries. The earliest claimant is said to be Hero. the Alexandrian philosopher, who developed the aeolipile, a machine for converting steam pressure into mechanical power, and, so the legend goes, put his apparatus (a kind of steam-kettle with two spouts) to practical use by linking it to a series of pulleys which opened the Palace Gates of Alexandria. The line of jet development then runs through an Italian engineer of the sixteenth century, a French missionary in China and Sir Isaac Newton, one of whose prin- ciples gave rise to Newton's steam-carriage, a horseless vehicle which progressed by blowing steam backwards. Then, in 1791. 160 years ago, another Englishman, John Barber, took out the first patent for a gas-turbine.
When Whittle began his work just over twenty years ago, a number of European engineers, notably in Switzerland, Italy, Sweden and Germany, were seriously considering projects for a gas-turbine engine. Whittle, when still a flight cadet at Cranwell, wrote a thesis on the future development of aircraft, which led him to think over possible types of power-unit. Finally he hit on the idea of a combination of gas-turbine with jet propulsion to make a turbo-jet engine. In January. 1930, he applied for and obtained a patent for his engine, and then, although only 23 years old, approached the Air Ministry with a notebook and drawings and a carefully thought-out argument, to ask for its backing for the development of the engine he proposed to design. At that time the Air Ministry believed the gas-turbine to be impracticable for propulsion because of the high temperatures involved, and it refused. Whittle then tried to sell his idea to private industry, but with no success. So from 1930 onwards a period of about six years went by in which almost no work on aircraft gas-turbine was done in England. and Whittle let his basic patent expire rather than pay a renewal fee. During these six years the Royal Air Force, believing him to
be a promising engineering officer, sent Whittle to Cambridge to take the Tripos in Mechanical Sciences. It was there that he acquired a thorough knowledge of the latest advances in aero- dynamics, and there, too, he was approached by two former officers who proposed 'forming a company to develop a com- mercial engine, a project which led to the formation of Power Jets, Limited. The Air Ministry agreed to allow Whittle to work for six hours a week as chief engineer of Power Jets, and late
• in 1935 he designed an engine 'for bench-tests, though not for flying, and in June, 1936, placed an order for its construction with a large engineering company. The work continued under private enterprise, and by 1937 enough progress had been made to convince men like Sir Henry Tizard of the future value of
jet propulsion, with the result that the Air Ministry agreed to make Power Jets a series of small grants. In July, 1939, when war was imminent, the Government finally made the decision to cover the cost of all future work by Power Jets.
Up to the war Whittle's engine had been regarded by the Government as purel■ a " research " project. with little possibility of practical application. But from 1939 onwards this attitude slowly changed, particularly when Arthur Tedder began to take a personal interest and speeded up development beyond
that normally given to a " research " project. In August, 1939. the Government authorised Gloster. the Aircraft Company, to design an aircraft (the E28/39) based on the Whittle engine. The Gloster designer, W. G. Carter, has described his first visit to Whittle's laboratory in an old foundry at Lutterworth. "This first gas-turbine-cum-jet propulsion unit seemed," says Carter. "a quaint kind of contraption—rather on the rough-and-ready side—and by no means the kind of thing to inspire confidence. . . . Some parts of the engine-casing showed a dull red heat. which, combined with an intensely high-pitched volume of noise. made it seem as if the engine might at.any moment disintegrate."
During the next two years Whittle worked on the construction of a flying engine, and Gloster completed the aircraft. By the end of April, 1941, F./Lt. P. E. G. Sayer and Wing-Commander Whittle were able to begin taxi-ing tests. Cranwell. where Whittle had first begun his studies, was chosen for the first flight primarily because of its long runways, and on the evening of May 15th, at 7.40 p.m.. Sayer took off for a flight of seventeen minutes. On the first page of the flight report. he made that evening. Sayer wrote, opposite the heading " Airscrcw," "No airscrew necessary with this form of propulsion."
Tests continued throughout the following year, and in the spring of 1943 a second aircraft, fitted with a more powerful engine, was flown across country and demonstrated before Mr. Churchill and members of the Air Staff. In June of the same, year Mr. John Grierson took off before breakfast and 'climbed to 42.170 feet, a new record. Meanwhile America was also forging ahead with jet propulsion, the work being based on a Whittle engine sent to the U.S.A. in 1941. and the R.A.F. was building a jet fighter, later to go into service as the Meteor. Eventually, in January, 1944, Britain and America made an official joint disclosure of the existence of jet-propelled aircraft.
The history of jet propulsion in the last ten years shows a rate of progress paralleled by few other forms of technical development. Sir Frank Whittle, a junior R.A.F. officer in 1941, is today the adviser oil...civil jet transport to B.O.A.C., which is just about to begin world-wide flights with the Comet airliner. His first aircraft. the Gloster-Whittle E28/39, is now in honour- able retirement at the Aeronautical Collection of the Science Museum at South Kensington. It is unlikely that normal development processes would have produced a Meteor lighter in 1944, or, perhaps, a Comet in 1948, but for the fact that the work was forced on by a knowledge of what the Germans were doing in the same field. The R.A.F.'s insistence on the virtues of speed and altitude meant that the jet (which was supreme in both) was developed at the expense of the piston-engine, which otherwise might have had some years of useful development ahead of it.
This supremacy of the jet was perpetuated after the war in the realm of civil transport because of another " accident " of history. What was begun by force of circumstances was con- tinued by a definite decision—the decision to head straight for the gas-turbine-powered transport and to by-pass the field in
which the Americans had already established a war-time lead. that of large civil transports powered by piston-engines. Today Britain leads the world in the design of civil jet airliners, and has continued to produce jet engines of increased power and ' efficiency. In the early days of the jet engineers were heard to say that they would soon " develop " the simplicity out of Whittle's engine. They have certainly done so, while at the same time increasing thrusts from the 1.200 lb. of his W.1 to • the 7,000-10,000 lb. which are to be expected from some of the • latest power units. Whittic's centrifugal type of turbo-jet is now • reinforced by other types—the axial, which has a smaller diameter and an improved fuel-consumption, and the compound, • which combines piston and gas-turbine units. A major develop- :• ment, started in 1941. is the turbo-prop (using the turbine to drive a propeller), which also exists in a coupled version where two distinct units drive one propeller-Thaft.
Still other types of power unit will replace or supplement the gaszturbine for future jet-propelled aircraft. Rocket-motors, ram-jets and pulse-jets may all have a place in the scheme of things, particularly for guided missiles for the armed services. In civil aviation, where reliability and economy are more important virtues than spectacular performance, the turbo-jet and turbo- prop will continue to be used for many years to come, continuing • the work of the pioneers who, like few pioneers, have seen success in a decade.
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