Helmut Schelp
Encyclopedia
Helmut Schelp was the director of "advanced" engine development at the RLM
's T-Amt technical division leading up to and during World War II
. He used his office to fund a widespread program in jet engine
development, which led to many of the engine concepts still used today. In particular, he was instrumental in favoring the use of axial compressor
s over the simpler but "fatter" centrifugal compressor
s. Unlike in England
where the jet had no single champion within the Air Ministry
and their efforts were long delayed as a result, Schelp can be directly credited with the advancement and refinement of the jet in Germany
over a few short years.
Schelp received a MSc in engineering
at Stevens University in Hoboken, NJ, before returning to Germany in 1936. On his return to Germany he was invited to join a new advanced course in aeronautical engineering being offered by the DVL research institute in Berlin
. Following in Frank Whittle
's footsteps of a few years earlier, Schelp became interested in the problems of high-speed flight, and attempted to calculate the maximum speed an aircraft could obtain. He eventually came to the conclusion that flights over Mach 0.82
were impossible due to the decreasing efficiency of propeller
s, which one of his professors at DVL demonstrated would be only 71% at Mach 0.82, and falling rapidly. For higher speeds a much larger engine would be needed, one whose weight would offset the amount of thrust that could be generated by the propeller. He was aware of developments in jet engines, and became convinced they were the only way forward.
In August 1937 Schelp joined the T-Amt's LC1 technical department, their short-lived pure-research arm. Neither LC1 nor DVL shared his enthusiasm for the jet engine, but when the RLM was re-organized in 1938, he found himself in the LC8 division which organized aircraft engine
development. Here he found an ally in Hans Mauch, in charge of rocket
and pulsejet development within LC8, who had seen a demonstration of Hans von Ohain
's engine at the Heinkel
works. Mauch was adamant that engine companies work on such projects, however, and refused official funding for Heinkel's developments as they were taking place at an airframe company. However Mauch and Schelp did meet with most of the larger engine companies, notably BMW
, Bramo, Jumo
and Daimler-Benz
, none of whom proved to be terribly interested, mostly because they were in the midst of bringing new piston designs into production.
Eventually the jet engine concept started to become more widely-known within the RLM, and Schelp and Mauch started to push for the immediate development of a flightworthy model. By the end of 1939 such a project was in place, with Schelp as its lead. This program was directly opposed by Wolfram Eisenlohr, director of LC8 (now known as GL/C3 after yet another re-org), who felt that a longer term project was needed to develop such a new concept. Eventually matters came to a head when Ernst Udet
, director of the T-Amt as a whole, overruled Eisenlohr, allowing development to continue. By 1941 the engines appeared to be maturing quickly and even Eisenlohr was convinced the project was worthwhile, becoming a strong supporter.
Schelp proposed a program consisting of three classes of engines, Class I were early designs like the Junkers Jumo 004
and BMW 003 that were suitable only for light fighters
or somewhat larger twin-engine designs, Class II were larger and more advanced engines suitable for reasonably-sized single-engine fighters and twin-engine light bomber
s, and Class III were very large engines suitable for larger bombers. In order to move such a program along, Schelp told Heinkel to stop working on the Class I Heinkel HeS 8 and Heinkel HeS 30
engine designs, and concentrate only on the Class II Heinkel HeS 011. At the time, in 1942, this decision made sense considering that two other Class I engines appeared to be ready to enter production. The eventual three year delay before the 003 or 004 entered service may have meant the HeS 30 would have beaten them to service, and in the end the HeS 011 would never leave the prototype phase.
Schelp also used his influence to force Heinkel to develop one of his pet projects, the "diagonal compressor", a sort of combination of the centrifugal and axial designs. At the time the pure axial compressors were having problems with surging and air intake turbulence, while the centrifugal designs proved fairly immune to these problems. Although it was mechanically possible to arrange a centrifugal stage in front of axial ones, this arrangement would require a large frontal area, and a small frontal area was the only real reason to use an axial arrangement. Schelp's diagonal stage appeared to offer the best of both worlds, only slightly larger than an axial stage of the same air flow, but with much wider-chord blades that should be more resistant to airflow problems. Schelp demanded that the HeS 011 use this design, which proved to be much more difficult to build than originally thought, and led to lengthy delays in that project.
After the war, Schelp was taken to London
where he was on 24-hour call if anyone in the Air Ministry
wanted to talk to him. This was rarely done, and Schelp found himself able to wander London at will. On one such trip he came across the Gloster E.28/39
, bearing a plaque that stated it was the first turbojet powered aircraft to fly. It had actually been beaten into the air by over a year by the Heinkel He 178
, and when Schelp pointed this out it was wryly suggested there may be some inaccuracy with the plaque. The correct lineage now appears on the E.28 display at the Science Museum
.
Reich Air Ministry
thumb|300px|The Ministry of Aviation, December 1938The Ministry of Aviation was a government department during the period of Nazi Germany...
's T-Amt technical division leading up to and during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. He used his office to fund a widespread program in jet engine
Jet engine
A jet engine is a reaction engine that discharges a fast moving jet to generate thrust by jet propulsion and in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets...
development, which led to many of the engine concepts still used today. In particular, he was instrumental in favoring the use of axial compressor
Axial compressor
Axial compressors are rotating, airfoil-based compressors in which the working fluid principally flows parallel to the axis of rotation. This is in contrast with other rotating compressors such as centrifugal, axi-centrifugal and mixed-flow compressors where the air may enter axially but will have...
s over the simpler but "fatter" centrifugal compressor
Centrifugal compressor
Centrifugal compressors, sometimes termed radial compressors, are a sub-class of dynamic axisymmetric work-absorbing turbomachinery.The idealized compressive dynamic turbo-machine achieves a pressure rise by adding kinetic energy/velocity to a continuous flow of fluid through the rotor or impeller...
s. Unlike in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
where the jet had no single champion within the Air Ministry
Air Ministry
The Air Ministry was a department of the British Government with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964...
and their efforts were long delayed as a result, Schelp can be directly credited with the advancement and refinement of the jet in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
over a few short years.
Schelp received a MSc in engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
at Stevens University in Hoboken, NJ, before returning to Germany in 1936. On his return to Germany he was invited to join a new advanced course in aeronautical engineering being offered by the DVL research institute in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
. Following in Frank Whittle
Frank Whittle
Air Commodore Sir Frank Whittle, OM, KBE, CB, FRS, Hon FRAeS was a British Royal Air Force engineer officer. He is credited with independently inventing the turbojet engine Air Commodore Sir Frank Whittle, OM, KBE, CB, FRS, Hon FRAeS (1 June 1907 – 9 August 1996) was a British Royal Air...
's footsteps of a few years earlier, Schelp became interested in the problems of high-speed flight, and attempted to calculate the maximum speed an aircraft could obtain. He eventually came to the conclusion that flights over Mach 0.82
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...
were impossible due to the decreasing efficiency of propeller
Propeller
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...
s, which one of his professors at DVL demonstrated would be only 71% at Mach 0.82, and falling rapidly. For higher speeds a much larger engine would be needed, one whose weight would offset the amount of thrust that could be generated by the propeller. He was aware of developments in jet engines, and became convinced they were the only way forward.
In August 1937 Schelp joined the T-Amt's LC1 technical department, their short-lived pure-research arm. Neither LC1 nor DVL shared his enthusiasm for the jet engine, but when the RLM was re-organized in 1938, he found himself in the LC8 division which organized aircraft engine
Aircraft engine
An aircraft engine is the component of the propulsion system for an aircraft that generates mechanical power. Aircraft engines are almost always either lightweight piston engines or gas turbines...
development. Here he found an ally in Hans Mauch, in charge of rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
and pulsejet development within LC8, who had seen a demonstration of Hans von Ohain
Hans von Ohain
Hans Joachim Pabst von Ohain was a German engineer, one of the inventors of jet propulsion.Frank Whittle, who patented in 1930 in the United Kingdom, and Hans von Ohain, who patented in 1936 in Germany, developed the concept independently during the late 1930s...
's engine at the Heinkel
Heinkel
Heinkel Flugzeugwerke was a German aircraft manufacturing company founded by and named after Ernst Heinkel. It is noted for producing bomber aircraft for the Luftwaffe in World War II and for important contributions to high-speed flight.-History:...
works. Mauch was adamant that engine companies work on such projects, however, and refused official funding for Heinkel's developments as they were taking place at an airframe company. However Mauch and Schelp did meet with most of the larger engine companies, notably BMW
BMW
Bayerische Motoren Werke AG is a German automobile, motorcycle and engine manufacturing company founded in 1916. It also owns and produces the Mini marque, and is the parent company of Rolls-Royce Motor Cars. BMW produces motorcycles under BMW Motorrad and Husqvarna brands...
, Bramo, Jumo
Jumo
Jumo is a social network service and website launched on November 30, 2010, to index charities so that people can find and evaluate them. Jumo was founded by Facebook co-founder Chris Hughes. On August 17, 2011 he announced Jumo was merging with the GOOD organization, providing a social engagement...
and Daimler-Benz
Daimler-Benz
Daimler-Benz AG was a German manufacturer of automobiles, motor vehicles, and internal combustion engines; founded in 1926. An Agreement of Mutual Interest - which was valid until year 2000 - was signed on 1 May 1924 between Karl Benz's Benz & Cie., and Daimler Motoren Gesellschaft, which had...
, none of whom proved to be terribly interested, mostly because they were in the midst of bringing new piston designs into production.
Eventually the jet engine concept started to become more widely-known within the RLM, and Schelp and Mauch started to push for the immediate development of a flightworthy model. By the end of 1939 such a project was in place, with Schelp as its lead. This program was directly opposed by Wolfram Eisenlohr, director of LC8 (now known as GL/C3 after yet another re-org), who felt that a longer term project was needed to develop such a new concept. Eventually matters came to a head when Ernst Udet
Ernst Udet
Colonel General Ernst Udet was the second-highest scoring German flying ace of World War I. He was one of the youngest aces and was the highest scoring German ace to survive the war . His 62 victories were second only to Manfred von Richthofen, his commander in the Flying Circus...
, director of the T-Amt as a whole, overruled Eisenlohr, allowing development to continue. By 1941 the engines appeared to be maturing quickly and even Eisenlohr was convinced the project was worthwhile, becoming a strong supporter.
Schelp proposed a program consisting of three classes of engines, Class I were early designs like the Junkers Jumo 004
Junkers Jumo 004
The Jumo 004 was the world's first turbojet engine in production and operational use, and the first successful axial compressor jet engine ever built. Some 8,000 units were manufactured by Junkers in Germany during late World War II and powered the operational Messerschmitt Me 262 jet fighter,...
and BMW 003 that were suitable only for light fighters
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
or somewhat larger twin-engine designs, Class II were larger and more advanced engines suitable for reasonably-sized single-engine fighters and twin-engine light bomber
Light bomber
A light bomber is a relatively small and fast class of military bomber aircraft which were primarily employed before the 1950s. Such aircraft would typically not carry more than one ton of ordnance....
s, and Class III were very large engines suitable for larger bombers. In order to move such a program along, Schelp told Heinkel to stop working on the Class I Heinkel HeS 8 and Heinkel HeS 30
Heinkel HeS 30
-Further reading:*German Jet Engine and Gas Turbine Development 1930-1945, Antony Kay, Airlife Publishing, 2002....
engine designs, and concentrate only on the Class II Heinkel HeS 011. At the time, in 1942, this decision made sense considering that two other Class I engines appeared to be ready to enter production. The eventual three year delay before the 003 or 004 entered service may have meant the HeS 30 would have beaten them to service, and in the end the HeS 011 would never leave the prototype phase.
Schelp also used his influence to force Heinkel to develop one of his pet projects, the "diagonal compressor", a sort of combination of the centrifugal and axial designs. At the time the pure axial compressors were having problems with surging and air intake turbulence, while the centrifugal designs proved fairly immune to these problems. Although it was mechanically possible to arrange a centrifugal stage in front of axial ones, this arrangement would require a large frontal area, and a small frontal area was the only real reason to use an axial arrangement. Schelp's diagonal stage appeared to offer the best of both worlds, only slightly larger than an axial stage of the same air flow, but with much wider-chord blades that should be more resistant to airflow problems. Schelp demanded that the HeS 011 use this design, which proved to be much more difficult to build than originally thought, and led to lengthy delays in that project.
After the war, Schelp was taken to London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
where he was on 24-hour call if anyone in the Air Ministry
Air Ministry
The Air Ministry was a department of the British Government with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964...
wanted to talk to him. This was rarely done, and Schelp found himself able to wander London at will. On one such trip he came across the Gloster E.28/39
Gloster E.28/39
|-See also:-References:NotesBibliography* James, Derek N. Gloster Aircraft since 1917. London: Putnam, 1987. ISBN 0-85177-807-0.* Mondey, David. The Hamlyn Concise Guide to British Aircraft of World War II. London: Chancellor Press, 1994. ISBN 1-85152-668-4.* Morgan, Eric B. "A New Concept of...
, bearing a plaque that stated it was the first turbojet powered aircraft to fly. It had actually been beaten into the air by over a year by the Heinkel He 178
Heinkel He 178
|-See also:*List of firsts in aviation-Bibliography:* Warsitz, Lutz: The First Jet Pilot - The Story of German Test Pilot Erich Warsitz, Pen and Sword Books Ltd., England, 2009, ISBN 9781844158188.-External links:...
, and when Schelp pointed this out it was wryly suggested there may be some inaccuracy with the plaque. The correct lineage now appears on the E.28 display at the Science Museum
Science Museum (London)
The Science Museum is one of the three major museums on Exhibition Road, South Kensington, London in the Royal Borough of Kensington and Chelsea. It is part of the National Museum of Science and Industry. The museum is a major London tourist attraction....
.