|
Genesis of the Jet Age Tuesday, November 25, 2008 - Daniel Uziel Home >> Personal Column >> Dr. Daniel Uziel   
|
|
|
Jet engine technology was one of those historical technological breakthroughs that happened in several places at the same time. The most important research and development work was carried out in England and Germany. This column will try and take a look at the way jet technology was developed in parallel in England and in Germany. It will also show the different paths these R&D programs took in both countries and how it influenced their outcome.
|
||||||||||||
Ohain, on the other hand, was introduced in 1936 to Ernst Heinkel – one of the most important aircraft designers in Germany and a major aircraft producer. Heinkel was highly interested in fast flight and he immediately grasped the potential of the new engine. He hired Ohain and allowed him to continue his work using his big firm’s resources. As a result of this move, other German aero engine manufacturers also started developing jet engines. When war broke out, jet technology development work became relatively widespread in Germany’s aviation industry.
It was realized however at the same time, that the development potential of the centrifugal-flow engine was limited. The biggest disadvantage of this type of engine was the need for a single large diameter compressor in order to provide enough compressed air into the combustion chambers. In order to increase the thrust of such engine, a larger diameter compressor was required. As a result, centrifugal-flow engines were stubby. It was difficult to fit them into streamlined and aerodynamically efficient fuselages or engine nacelles. Furthermore, indirect flow of air through the engine reduced the efficiency of the centrifugal-flow engine.
Generally, jet engine development was extremely challenging because its operation created very high temperatures and greater rotational speeds then piston engines. Both Whittle and Ohain experienced many failures and accidents while refining their engines. During some of Whittle’s engine first test runs the engine went out of control and disintegrated.
While the He 178 demonstrated the new technology, initial blueprints for axial-flow engines were prepared in the design bureaus of the Jumo (Junkers’ aero engine division) and BMW aero engine manufacturers in Germany. Once again, Germany was not alone in this field. British jet propulsion theoretician A.A. Griffith suggested such engines in the 20s, and in the late 30s the Metropolitan- Vickers firm started developing a turbo-prop engine (jet engine driving a normal propeller) based on his design. In 1940 the firm gave up the turbo-prop design and started working on a pure jet engine based on the axial-flow design. The new engine, called F.2, showed a greater potential then Whittle’s design, but suffered from numerous technical problem. Its development was terminated in 1944, but its technology was later used as a basis for the successful postwar Sapphire engine.
Axial-flow engine is constructed around a long axis, with a compressor on one end, and a turbine on the other end. The single combustion chamber is located between them and the hot gases blown rearwards propel the turbine and provide thrust. The most important advantages of the axial-flow design are its relatively small diameter and the ability to add more compressor fans in a row in order to compress a larger mass of air, and therefore increase thrust. Furthermore, the flow of air through the engine is linear – a feature that increases its efficiency.
The biggest problems with this engine at that time were its novelty and need of stronger parts and components due to its higher thrust.
In England, Whittle and his startup finally received some support from the Air Ministry and on May 15, 1941, the first British jet aircraft – the Gloster E28/39 – finally took to the air. It was powered by the prototype W.1 engine. Whittle then moved on to develop the improved W.2 engine and prepare it for series production. As happened to Ohain, at that point British Air Ministry marginalized Whittle after he made the big breakthrough. Since Power Jets possessed no production facilities, car manufacturer Rover was contracted to perform series production. Slowly but surely Whittle started losing control on his engine. Further development and production of the W.2 was nationalized and given to other firms, including Rolls Royce (which purchased Rover’s jet engine factory in 1943) and de Havilland.
The Germans were legging behind production-wise because they concentrated their efforts on the more advanced axial-flow engine. This engine was more complicated and therefore took longer to develop and make ready for series production. Its production was also difficult because of the special heat-resistant metals it required. The huge technical challenges this type of engine posed are well demonstrated by the fact that centrifugal-flow engines still powered the most modern jet fighters of the Korean War - the F-86 and Mig-15.
Centrifugal-flow engines filled the void until axial-flow technology matured. This ripening process was a long one, and was partially based on German developments, but it was the future of jet propulsion and during the 50s axial-flow engines became the most common type of jet engine.
About the author: Dr. Daniel Uziel researches different aspects of modern German history, military history, and war and media. In recent years he is researching the history of the German aviation industry. He conducted part of this research as a fellow at the US National Air & Space Museum. |
||||||||||||
|
| Other News |
|
Brain Surgery With Sound Waves |
|
Bird Flu Vaccination Ready? |
| Other Pictures |
|
xTablet T8700 – Rugged Tablet PC |
|
Smoother Landings |
|
|
|||
|
|||
|
While the MiG-15 engine was indeed of centrifugal flow type (see here:http://en.wikipedia.org/wiki/Rolls-Royce_Nene) The F-86 engine was of Axial flow type as can be seen here:http://www.wingweb.co.uk/engines/Allison_J35_turbojet.html) |
|||
|
|||
|
You are right. Actually it was the improved J47 engine. Somehow I remembered it as a centrifugal flow engine. |
|||
|
|||
|
I have a personal interest in this topic, as my father was Michael Daunt OBE, Chief Test Pilot at Gloster Aircraft Co 1942 - 1944. He was involved in testing the early jets. The first flight was commemorated in a print called "Breakthrough" |
|||
|
|||
|
On 26 July 1944, Leutnant Alfred Schreiber with the 262 A-1a W.Nr. 130 017 damaged a Mosquito reconnaissance aircraft of No. 540 Squadron RAF PR Squadron, which was lost in a crash landing upon landing at an air base in Italy.[16] It was the first victory for a turbojet fighter aircraft in aviation history.[ |
|||
|
|||
|
http://gearturbine.260mb.com YouTube Video; Atypical New * GEARTURBINE / Retrodynamic = DextroRPM VS LevoInFlow + Ying Yang Thrust Way Type - Non Waste Looses http://www.youtube.com/watch?v=0cPo9Lf44TE GEARTURBINE -Atypical Combustion Turbine Engine, -State of the Art, -New Thermodynamic Technology, -With Retrodynamic "Dextrogiro vs Levogiro" Effect, is when the inflow direction moves is against [VS] of the circular rotary dynamic / RPM Rotor Move VS Inflow Conduits Way /ACTION VS REACTION / Front 2 Front / Velocity vs Velocity, making in a simple way a very strong concept of power thrust, a unique technical quality. -Cilindrical shape dynamic mass (continue Inertia cinetic positive tendens motion / all the motor weight is goin with the power thrust direction), -Non Waste, parasitic losses form-function engine system for; cooling, lubrication & combustion; -Lubrication & Combustion inside a conduit radial position, out way direction, activated by centrifugal force. |
|||
|
|||
|
christian louboutin louboutin christian louboutin shoes christian louboutin sale christian louboutin discount christian louboutin louboutin louboutin shoes louboutin sale christian louboutin discount Vibram FiveFingers Vibram Five Fingers FiveFingers Five Fingers Five Finger shoes |
