Fred Starr recollects…
Fred Starr explores the lost potential of jet engine pioneer Sir Frank Whittle.
A few years back, I went to a talk by Ian Whittle about his father, Sir Frank Whittle, inventor of the jet engine. The contribution I made to the discussion and what I did to follow up my assertions will change what is said about the early history of jet propulsion. A related conjecture is, if Whittle had gained proper support, the world might have turned out for the better.
Ian showed a sketch of a jet engine his father had conceived in 1929, before Frank had been granted his first patent. As shown, this two-stage centrifugal compressor, two-stage turbine looks practical. However, as Ian went onto to explain, this design was beyond the capabilities of the materials of the time. Ian, an ex-RAF and airline pilot, was repeating the line of the superalloy fraternity, that before Nimonics there was nothing. Frankly, these groups should have had a better understanding of the history of high-temperature materials.
I interjected to point out that the proposed jet engine would turn at quite a modest RPM, resulting in low turbine blade stresses. This feature, combined with the modest turbine inlet temperature of 715°C, suggested that the engine was quite practical, and there were materials around at that time which would have been good enough to realise it. I was able to say this, having written a number of papers on the development of alloys for the poppet valves in petrol engines. Until jet propulsion came along, this was the most challenging of high-temperature issues. Even now, poppet valves still pose challenges although the main driver is the need for lighter weight alloys, such as the titanium aluminides mentioned in Materials World, June 2019, page 36.
No World War II?
My subsequent calculations showed that using the best poppet valve material of the time, KE 965, a complex austenitic stainless, Whittle’s engine would have worked. This British alloy was actually being used by GE, then General Electric Inc, for the blading of its aircraft engine turbochargers – in some respects an environment more demanding than that of the jet. I estimated that the proposed engine would have given a thrust of 1,100lb - two to three times the power of any commercial piston engine, in horsepower terms.
It is stimulating to consider what might have happened if Whittle’s engine had been built and the concept taken up in this country. Given that the cost and development time of early jets was just a third of comparable piston engines, the British government would have been able to equip the RAF with squadrons of fighters capable of around 500MPH. We would have had a real deterrent to the growing threat from Germany. Furthermore, Whittle, having the master patent, could have prevented Germany from getting into the jet engine race.
Read Frank Whittle’s thesis
I formed a strong relationship with Ian, as both of us share the view that his father was badly treated by the government and aviation establishment. Whittle was prevented from manufacturing jet engines and was paid off with a knighthood and £100,000. Not much more than several million pounds in modern money.
Many accounts support this opinion, but what they also say is the idea of the jet engine and jet propulsion originated in the thesis Frank Whittle wrote at RAF Cranwell in 1928, when he was undergoing officer training. Ian lent me a copy and it is not the easiest thing to read. Whittle’s course leader at Cranwell, Professor Sinnatt, was being more than diplomatic when he wrote, ‘It would be difficult to comment without rewriting the thesis. The thesis shows much careful and original thought and also a good deal of private reading’.
Accordingly, I think I am the first person to have gone through the thesis properly, finding to my amazement that it contains nothing about jet propulsion. In 1928, Whittle had only just started on that road, with the thesis envisaging a propeller-driven aircraft flying at 600MPH and nearly 37,000m high. He did make use of a gas turbine to provide a direct drive to the propeller, but it is not a turboprop as we would understand it. Whittle’s unique configuration enabled him to circumvent turbine materials issues.
Thanks to the help of the historical branch of the Royal Aeronautical Society, you can view Whittle’s handwritten thesis online, plus a word-for-word transcription of the effort. The web page also contains a commentary by me of what Whittle had accomplished, putting it in context of the aviation industry as it then was. If the general public think support for students and academic research is a waste of money, they would think differently if they knew more about Frank Whittle.
You can read more about Frank Whittle’s work here: bit.ly/32wuKyj