The Langdales from Moss Eccles TarnFrank Whittle and the Jet Engine
A Schoolboy's Essay
The Langdales from Moss Eccles TarnA Schoolboy's Essay
The fan at the front of the engine sucks in a large amount of air which in turn is injected into the small combustion chamber by a series of low and high pressure compressors, here the compressed air is mixed with vaporised fuel and ignited. This rapid expansion of gases, creates forward thrust as they are expelled through the exhaust. Another factor involved in this process is something called bypass ratio, which describes how much air goes through the bypass ducts of the engine compared to that which goes through the core. An advantage of a higher bypass ratio is that the engine is more efficient, while still providing the same amount of thrust.[1] A useful feature that will allow planes to travel further using less fuel, potentially opening up the market to more people.
The jet engine was invented by Frank Whittle, whose patent was approved on the 16th of January 1930, however he had been thinking of this solution for high altitude and high-speed flying for a few years previously. In 1928, he had submitted his ideas to his superiors at RAF College Cranwell, where he was training at the time. These were initially turned down, and when he looked for backing elsewhere he found people were unwilling to invest due to the high cost of experimental research at the time.[2] This meant the start of development was delayed by several years.
However, in 1935, after attending Cambridge University for two years, he received a letter from R.D. Williams, another RAF member, who Whittle had met at RAF Cranwell, saying that he had found someone who was interested in his idea of a turbofan engine. A year later, he founded a company called "Power Jets," with two other RAF Servicemen, R.D. Williams, and J.C. Tinling. That year they partnered with a company called British Thomson-Houston (BTH) to help manufacture the test models of Power Jets' turbofan engine.[3] This kickstarted Frank Whittle's journey towards creating the first ever jet engine, without which progress might have been delayed for possibly decades.
Finally, on the 12th of April 1937, Frank Whittle became the first person to run a turbojet engine, however despite this success, a lack of funding at Power Jets and the outbreak of WW2, resulted in further development being rather slow from this point. In July 1939, a speed of 16,650 rpm was achieved, which was 94% of the designed speed for the W.1 (The first engine Whittle designed). In addition to this, development was further boosted when Power Jets received additional funding from BTH and another partner G. Weir, accelerating testing and development and the engines' potential commercial availablity. [4]
In 1940, due to the tension between the two companies at the time, Power Jets had meetings with the Rover Car Company, where they discussed arrangements similar to those that they had with BTH. When Whittle contacted the Air Ministry about this, he was told the Rover Company were not allowed to work with Power Jets or see the engine that had been made so far, however the Rover Company would go on to help with Whittle's designs, before the project was handed over to Rolls-Royce.[5] This decision by the Air Ministry meant progress in 1940 was slow, due to the focus on aircraft production for the war effort
In 1941, senior officials from Rolls-Royce visited the Lutterworth works, where Power Jets was operating at the time, they became very interested in Whittle's project, and eventually became one of the only aerospace engine manufacturers to be involved in turbojet engine manufacture.[7] This visit proved critical to the aviation industry, it meant that finally a big company with much influence was interested in Whittle's work, speeding up the development process to completion, with Rolls-Royce providing valuable resources and facilities.
In 1942, Whittle travelled to the USA to see if he could promote greater interest in his invention. He had sent one of his W.1s in autumn the previous year to General Electric, who where working on a supercharger for his engine.[8] This venture opened up his project to a wider market, boosting prospects, speeding development to completion and proved a major step forward for the aviation industry.
In 1939, the Heinkel He 178 was the first plane to be powered by a turbojet engine[10]. This plane was designed by Heinkel and was powered by an engine designed by Whittle's main rival, Hans von Ohain, who worked for the company.
Later in the development process, Whittle encountered a problem to do with the amount of twisting in the turbine blades during testing of his engine. To fix this he came up with the idea of a vortex flow design for the turbines [11], causing some upset within BTH, given that Whittle was not an expert in the field of turbines, and he was telling them they had been doing it wrong the whole time. However the design change he proposed proved successful and the engine became even more fuel efficient, further improving the range and of course, its prospects for the future.
One of the constant worries for Power Jets throughout their journey, other than funding, was uneven temperatures and pooling of fuel in parts of the combustion chamber making the engine's operation rough and less efficient.[12] One of the solutions that Whittle and his associates came up with, initially seen as unnecessary by others at Power Jets, was the vaporisation of fuel before mixing with the compressed air for ignition, the second was to have 10 separate linked combustion chambers. These improvements resulted in a smoother a more controllable combustion process making testing more straight forward, measurements easier to record and results more accurate, again speeding up the rate of development.
The main type of power plant that the turbofan engine replaced was the turboprop/propeller engine. During the time that Whittle was developing his jet engine, it was generally thought that turboprops were reliable, and people knew that they worked and so were reluctant to invest in a new idea that had never been tried before, especially given the high development costs. The reasons why turboprops are still used today, for example in the De Havilland Dash 8, include the fact that they are lightweight and have a greater ability to land on short or grass surfaced runways, which jet powered aircraft aren't able to do. Other advantages include being efficient, cost effective and reliable with fewer moving parts than other types of engines.[13] However, there are some disadvantages to turboprops, these include having a lower cruising speed and operating altitude, which can limit the range. In addition to this, turboprop engines usually vibrate more, and the low operational altitude makes the aircraft more susceptible to turbulence and the possibility of passenger discomfort.[13]
The first fighter jet to be powered by a turbojet engine was the Messerschmitt Me 262, which first flew on the 18th of April 1941, however it first flew with a jet engine on the 18th of July 1942. It entered service in 1944, however was retired from the Luftwaffe in 1945. It had been described as one of the best fighters in WW2, and was effective at bombing, reconnaissance and as an experimental night fighter.[14]
An example of a more recent fighter jet to be powered by a version of Whittle's jet engine is the Lockheed Martin F-22 Raptor. This fighter jet was developed by Lockheed Martin for the USAF, and first flew on the 7th of September 1997, and was introduced into service in 2005. It was produced between 1996 and 2011, and is still in service today. It has been described as one of the stealthiest fighter jets of the modern age due to it being very difficult to detect on radar and difficult for other pilots to spot.[15]
Overall, the development of the jet engine has given military aircraft the ability to fly faster over a longer range, with most modern day fighter jets able to reach supersonic speeds, for example the F-22 is able to reach twice the speed of sound. Also because of the amount of thrust produced by the jet engine, the payload of the aircraft can be increased, requiring fewer aircraft for a single mission, and smaller numbers overall.
In 1949 the De Havilland Comet was first to fly, however the first airliner to enter regular service was the Boeing 707, which first flew in 1957 and entered service in 1958, 800 were produced in total until it was discontinued in 1978. It is no longer in commercial use, but is still used for military purposes. The Boeing 707 was powered by 4 Pratt & Whitney JT3D turbofans which provided 76,000 lbs of thrust in total. It had a range of around 7,000 km, and a MTOW weight of 112 tonnes.[16]
In 1969, Concorde flew for the first time, the first commercial aircraft to fly at supersonic speeds. It had a top speed of 2179 km/h, which is over Mach 2 (Twice the speed of sound). It was powered by four Rolls-Royce Olympus 593 turbojets, providing 40,000 lbs of thrust each. Concorde broke the record for a flight between London Heathrow and JFK airport in New York, by travelling between the two in 2 hours, 52 minutes and 59 seconds[9], showing just how quickly the jet engine changed the aviation industry, by going from an idea that people were sceptical about, to breaking records for long distance flights 30 years later.
An example of a more modern airliner is the Airbus A350. The A350 first flew on the 14th of June 2013, and went into service with Qatar Airways in 2015. It has been produced from 2010 until present day, and as of 31st of January 2024, 585 have been produced. It is powered by two Rolls-Royce Trent XWB high bypass turbofan engines, which provide 97,000 lbs of thrust in total, compared to the Boeing 707's 76,000 lbs. The A350 has a range of 15,000 - 16,000 km depending on the variation. It has a MTOW (Maximum Take-off Weight) of 280 - 320 tonnes, again depending on the variation.[17]
Overall, in the last 60-70 years, the jet engine has been developed significantly by companies such as Rolls-Royce, the A350 having 20,000 lbs more thrust than the Boeing 707. As well as becoming more powerful, they have become able to support more weight, with the A350 being able to carry 200 tonnes more than its predecessors, with 10,000 km extra range.
In summary, the jet engine has developed dramatically, from Frank Whittle first submitting his theory to his superiors at RAF Cranwell in 1928, to companies such as Rolls-Royce starting to investigate SAF's (Sustainable Aviation Fuels) to help make the aviation industry more sustainable, and importantly, if it hadn't been invented, air travel would still be very slow, and we might still be using ships for long distance travel. It is also likely we wouldn't have got to the moon as early as we did without its development and the subsequent links between the aviation industry and space travel.
[1] - How Do Turbofan Engines Work? (simpleflying.com)
[2] - Jet img-responsive Frank Whittle and the Invention of the Jet Engine by John Golley
[3] - Jet - Frank Whittle and the Invention of the Jet Engine by John Golley
[4] - Jet - Frank Whittle and the Invention of the Jet Engine by John Golley - Page 122
[5] - Jet - Frank Whittle and the Invention of the Jet Engine by John Golley - Page 135
[6] - Jet - Frank Whittle and the Invention of the Jet Engine by John Golley - Page 135
[7] - Jet - Frank Whittle and the Invention of the Jet Engine by John Golley - Page 140
[8] - Jet - Frank Whittle and the Invention of the Jet Engine by John Golley - Page 193
[9] - How Fast Did Concorde Actually Fly From New York To London? (simpleflying.com)
[10] - Heinkel He 178 - Wikipedia
[11] - Jet - Frank Whittle and the Invention of the Jet Engine by John Golley - Appendix 1 - Page 243
[12] - Jet - Frank Whittle and the Invention of the Jet Engine by John Golley - Appendix 1 - Page 243
[13] - How Do Turboprop Engines Work? | Skill-Lync
[14] - Messerschmitt Me 262 - Wikipedia
[15] - Lockheed Martin F-22 Raptor - Wikipedia
[16] - Boeing 707 - Wikipedia
[17] - Airbus A350 - Wikipedia
Pictures (top to bottom): De Havilland Sea Vemom; Whittle's Engine; Panavia Tornado; Boeing 757; Eurofighter Typhoon; Embraer ERJ145; Whittle's testbed Gloster E28/39 (first flown by Gloster chief test pilot Gerry Sayer 15th May 1941). NOTE: Frank Whittle 1907 - 1996 was born in Coventry UK and died aged 89 in Maryland USA.
D F. July 2024
The Herbaceous Border, Arley Hall Garden, Cheshire