Secret Weapons

by Brian Ford

  Meanwhile, engineers from the United States and Canada had been to visit Whittle. The Americans designed their own jet, based on the British research, the Bell P-59 Airacomet but it was an unsuccessful aircraft and lacked the power of the Gloster Meteor. Development work also went ahead with the National Research Council of Canada. In May 1943 their findings were published in a top-secret report entitled Report on Development of Jet Propulsion in the United Kingdom, which reached two important conclusions. One was the need to establish a group to study jet engines in cold conditions (this was an area of research nobody else had thought to embrace); the other was the importance of forming a Canadian jet company as quickly as possible. In March 1944 Turbo Research was formed in Toronto. At first they developed the Whittle centrifugal-flow jet engine, but they soon progressed to their own design for a new axial-flow design, the Chinook. As the war was reaching its end they began to manufacture their Orenda jet engine which had many crucial advantages: its longer combustion chambers and increased power meant that it was, at its time, the most powerful jet engine in the world. The engines sold were worth a quarter of a million Canadian dollars.

  Canadian researchers went further than anyone else among the Allies in investigating the protection of pilots at high altitude, and they constructed the first experimental decompression chamber in North America to study the effects of low air pressure on pilots. The result was the first anti-G suit to prevent pilots blacking out. It was invented by Wilbur Franks and became known as the Franks Suit. It was first used in 1942 by the Royal Navy pilots covering the Allied landings in North Africa.

  In Germany, meanwhile, during the closing months of the war, the Arado Company manufactured the first jet bomber, the Ar-234 Blitz (Lightning). It had twin engines and a single pilot, and was flown mostly for reconnaissance at altitudes around 36,000ft (11,000m) where it was impossible for it to be shadowed or intercepted. The project began late in 1940, when Arado proposed their design for a jet bomber with the designation E-370 designed by Professor Walter Blume. It was a jet-engined aircraft with a Junkers Jumo-004 engine fitted beneath each of the wings. The design weight of the aircraft was 17,600lb (8,000kg) and, to keep the weight down, there were no landing wheels. The plane ran on a three-wheeled trolley which was jettisoned after take-off, and it landed later on skids. The plane had a maximum design speed of 490mph (789km/h) with an operating altitude of 36,100ft (11,000m) and a range of 1,240 miles (1,995km). In April 1945 this became the last German warplane ever to fly over British soil during World War II. The Ar-234 was nicknamed the Hecht (Pike) and was described as a ‘blitz-bomber’ though in fact it never flew carrying a payload.

  British fighter pilots saw a remarkable jet fighter in the closing months of the war, though there are no records of any engaging in combat. This was the Heinkel He-162 Volksjäger (People’s Fighter), a single-seater aircraft with an H-shaped tail fin. It was built of glued wood and constructed by semi-skilled labour, and could achieve a top speed of 562mph (905km/h) at 19,690ft (6,000m). What makes this so remarkable is that it went from conception to test flight in just 90 days.

  Allied aircraft responded to the arrival of these amazing new jet aircraft by bombing the runways and factories where the planes were evident, and it was this relentless barrage coupled with a shortage of fuel that ensured that the Me-262, for all its technological sophistication and success in use, had limited impact on the course of the war. Nonetheless, the German designs went on to influence developments in the United States, notably the design of the Boeing B-47 and the North American F-86, better known as the Sabre jet, which was developed with the extensive involvement of German data from the war.

  After the war

  In Russia, work on jet engines had revived in the closing months of the war. From 1944 the Soviets had evidence of the British and German developments in jet engine design, and Lyulka was encouraged to try to improve them for use in Soviet aircraft. Starting in 1945 he constructed the first Soviet jet engine, the TR-1, which passed all the required tests successfully and went on to give rise to the engines which powered the highly successful MiG fighters. They were built by a company established in December 1939 by Artem Mikoyan, a young aviation designer from Sanahin, Armenia. Many of these Russian engines were copied from Junkers and BMW jet engines brought to Russia from Germany after the war. Then, in 1946, the new British Prime Minister Clement Attlee — keen to cement cordial relationships with the Soviet Union — arranged for an export of 40 Rolls-Royce Nene turbojet engines. It was hoped that further orders would follow, but instead the Russians simply copied the British design and constructed a pirated copy of the engine for use in the MiG-15. Rolls-Royce, with Government encouragement, sought to reclaim £207 million in license fees, but did not succeed.

  These MiG-15 fighters, used later in the Korean War, proved to be superior to anything in the West. The MiG-29 is the fourth-generation MiG fighter aircraft designed in the Soviet Union and was developed from the earlier designs during the 1970s by the Mikoyan Company. This aircraft entered service with the Soviet Air Force in 1983 and it remains in use to the present day by the Russian Air Force and also in several other countries.

  Hans Joachim Pabst von Ohain was brought to the United States in 1947 under the top-secret Operation Paperclip (see chapter 4). He joined the staff at the Wright-Patterson Air Force Base and in 1956 became Director of the Aeronautical Research Laboratory. In 1975 he was appointed to the role of Chief Scientist at the Aero Propulsion Laboratory. Ohain made innumerable contributions to American fuel technology and won many awards, including the United States Citation of Honor. Ohain eventually retired to Florida, where he died in 1998.

  Meanwhile, in 1976, Whittle had divorced from his British wife Dorothy and he married an American woman, Hazel S. Hall. He emigrated to the United States and became the NAVAIR (Naval Air Systems Command) Research Professor at the Naval Academy in Annapolis, Maryland. He later wrote a book entitled Gas Turbine Aero-Thermodynamics: With Special Reference to Aircraft Propulsion which appeared in 1981. He came to know Ohain, and the two often gave talks together. Ohain reportedly said that if the RAF had taken Whittle’s design seriously when it was originally submitted, there would have been no World War II at all. Sir Frank Whittle died in 1996 at his home in Columbia, Maryland.

  Small warplanes

  Not all the secret aircraft were fast, large or impressive. Small and discreet aeroplanes also played their part. The Arado Ar-231 was an extremely lightweight seaplane that the Germans designed as a spotter plane and it was intended to be carried aboard the U-boat Type XI B. The plane was designed with light parasol wings and was powered by a 160hp (119kW) Hirth HM 501 inline engine. The plane weighed 2,200lb (1,000kg) and had a wingspan of just 33ft (10m). It could be folded down within 6 minutes and fitted inside a tubular casing measuring 6.7ft (2m) across. Although it was an ingenious little portable aircraft, it proved to be seriously underpowered, too light to handle and unstable in flight, even when the weather was calm. With small waves causing unsteadiness in the mother submarine, it proved near-impossible to fold up the wings and store the plane away. Six prototypes were built for testing purposes, but it was never used in the war.

  Submarine commanders, however, knew that some means of carrying out reconnaissance was imperative. Current limitations were imposing severe restraints upon the U-boat campaigns. The distance of vision is severely restricted through a periscope, and some means of gaining height — as in the abandoned Ar-231 — conferred a considerable advantage. Accordingly, focus was directed instead to the notion of having an observer towed along underneath some kind of kite. This would not be just a conventional kite, either, but a superbly thought-out and well-designed kite with rotary wings.

  The project was put to the designers at the Focke-Achgelis Flugzeugbau (a division of Weser Flugzeugwerke) of Hoykenkamp in Lower Saxony, who were experienced in helicopter production. Since helicopters had emerged in their present-day form in 1936, their production had become rou
tine and companies like Focke-Achgelis Flugzeugbau were well equipped to tackle the problem. The Weser Flugzeugwerke were based at the Lloyd Building in Bremen, and they acted as the government contractors for the project; all development and manufacture, however, was carried out at Hoykenkamp. The result was the Focke-Achgelis Fa-330 gyroglider, an autogyro that could be tethered to the deck of a submarine at the end of a wire cable 500ft (150m) long. A minimum airflow of 20mph (32km/h) from the movement of the submarine caused the rotors to turn at about 200rpm, lifting the glider 400ft (120m) above the sea. The observer could spy out features up to 25 miles (40km) away, rather than being able to see just 5.5 nautical miles (10km) from the top of the submarine’s conning tower, and he could send back real-time reports by telephone. When observations were over, the Fa-330 was hauled down, the rotors stopped by means of a hub brake, and the craft stowed away in watertight compartments aft of the conning tower. This was not a simple task and could take 20–25 minutes in rough seas.

  The Fa-330 was nicknamed the Bachstelge (Sandpiper) and 200 were built. These little gliders were successful in use, but were disappointing as agents of warfare. There was only one instance when a sinking resulted from their use — a Greek steamer in 1943. They also posed a problem for the submarines, for they could be detected by British radar and thus inadvertently reveal the location of the submarine. Pilots of the Fa-330 were sometimes forgotten about by the captain of the submarine, which suddenly dived leaving the pilot and his craft doused in the sea. It soon became routine for the pilot to call down the line ‘Haul me in!’ before announcing that an enemy ship had been sighted. In May 1944 one of these gyrogliders was captured and examined by the Allies. Experiments were carried out by the British, but the helicopter was seen as a higher priority and the little rotary glider was never used again. Design of the Rotachute, a British single-seat gyroglider, was undertaken by an expatriate Austrian designer, Raoul Hafner. The design was modified by Dr Igor Bensen after he had seen one of the German Fa-330 gliders, and the Benson design became popular. This original Rotachute was intended to be towed behind an aircraft, and was not ready until 1946; but Benson’s B-7 gyroglider was a success and later re-emerged as a sports craft. It is still popular with enthusiasts today.

  The gyroglider was a form of aircraft similar to an autogyro — the essential difference being that the forward motion of an autogyro was provided by its own onboard propulsion system, whereas the gyroglider was towed by a moving vehicle. Autogyros were the invention of Juan de la Cierva, a Spanish engineer and flight enthusiast. His first successful design, the fourth with which he experimented (the C-4), flew in 1923. The aircraft had a forward propeller and engine with a rotor on a vertical mast. The C-19 was licensed to several overseas manufacturers, including Harold Pitcairn in the United States and Focke-Achgelis in Germany. Amelia Earhart flew a Pitcairn PCA-2 to a world-record altitude of 18,415ft (5,613m) in 1931.

  During the war, Germany also employed the Focke-Wulf Fw-186 and experimented with the Focke-Achgelis Fa-225 and the two-seater Flettner Fl-184. But it was the Spanish design of the La Cierva C.30A that was most successful. The United States used a version which they named the Kellet KD-1A; Britain and Canada produced their own models as the Avro 671 Rota Mark.1 and the French called theirs the Lioré-et-Olivier LeO C.30/31. The Soviets had their own design, the TsAGI (Kamov) A-7 observation autogyro. In the Pacific arena, the Japanese produced their Kayaba Ka-1 Autogyro for reconnaissance and for use as an anti-submarine observation aircraft. Although the war brought helicopters visibly into use as a crucial means of transporting men and materiel, we should also remember the small, secret ‘spy in the sky’ that was the autogyro. Autogyros remain popular to the present day, mostly as the aircraft of hobbyists, yet they flourished only because of the pressures of secret weapons development in the war.

  Flying wings

  The flowering of innovation in the development of German secret weapons during the war years was especially pronounced in the field of revolutionary aeronautics. Britain was consumed with finding responses to the German onslaught, but the German High Command became fanatical about the domination of the Western world. The engineers and visionaries came up with startling, stunning concepts, and the rate at which they progressed was astonishing. Some of the ideas could never reach fulfilment. One was for the 3 x 1,000 project, intended to bomb English cities. This was the aim of Reichsmarschall Hermann Göring, and would have involved a bomber carrying 1,000kg of explosives for 1,000km at 1,000km/h, equivalent to 2,200lb of bombs for 625 miles at 625mph.

  The birth of the ‘flying wing’ had been in the USA where Jack Northrop had experimented with delta-wing designs in the late 1920s. Little came of it, however, until the pressures of World War II led to new calls for revolutionary aircraft designs. Both the United States and Germany began development, but research took longer than expected. In Germany, two brilliant brothers, Walter and Reimar Horten, revived the concept during war and planned to take it to unprecedented heights. Both were members of the Hitler Youth and later of the Nazi Party. They first designed an unpowered delta-wing glider, the Ho-229, for flight testing, and its initial flight was in March 1944. After this successful test, the development was taken over by the Gothaer Waggonfabrik Company. They installed an ejector seat for the pilot, and added systems to carry air to the jet engine with which it was proposed to power the plane. Even before the aircraft had flown under jet power, Göring had an order placed for 40 of these aircraft with the designation Ho-229. Further test flights showed that the plane had superb handling qualities, though there were some tragic accidents during the test flights of prototypes. The Germans were building a twin-engined Ho-229 V3 when the Americans arrived during the liberation of Europe at the end of the war.

  During the final stages of the conflict, the United States military initiated Operation Paperclip, a top-secret initiative by the United States intelligence agencies to capture advanced German weapons research, and keep it out of the hands of advancing Soviet troops. A Horten test glider, and the partly built Ho-229 V3, were packed up and shipped to the United States, and the Hortens — for all their active Nazi participation — were secretly taken to America and given sanctuary. Their hardware was sent to Jack Northrop.

  The first of Jack Northrop’s new generation of planes, the N-1M, had taken to the air in July 1941 at Baker Dry Lake, California. These pioneering test flights showed that the design clearly had a future, though the plane’s twin 65hp (48kW) Lycoming 0-145 four-cylinder engines left it low on power and the construction was too heavy. The power-plants were replaced with 120hp (88kW) six-cylinder air-cooled Franklin engines and the design was modified though, in spite of it all, the plane never went into production.

  Engineering design of the first American delta-winged planes started in 1942. The aircraft would be constructed of the latest light-alloy sheet. There would be a cabin embedded in the delta wing with bunk beds for crew to sleep on during prolonged flights. Bomb bays would be fitted in each wing with seven gun turrets carrying machine guns. Yet progress was slow and the XB-35 did not make her first successful flight until June 1946 when she flew from Hawthorne, California, to Muroc Dry Lake. By May 1948 the plane was ready to start production, but the planes — powered by propeller engines — were rendered obsolete by the advent of the jet bomber. Jet engines were fitted to a few but they were not successful, though one plane, designated the YRB-49A, was tested as a reconnaissance aircraft. Although the United States Air Force had originally ordered 200 of the original B-35 planes, they proved unsatisfactory and not worth converting to jet propulsion so the entire project was peremptorily cancelled. It was a controversial decision, and Jack Northrop later stated that it was due to his refusal to accede to the wishes of Secretary of the Air Force Stuart Symington, who wanted Northrop to merge with the Convair Company. Jack Northrop insisted that unfair terms were being imposed on him, and that it was Symington who suddenly cancelled the flying wing. Northrop may have been right; Symi
ngton subsequently became President of the Convair Company when he resigned from government service shortly afterwards.

  The final legacy of the Horten brothers’ original design lives on, however. Their aircraft were intended not only to be aerodynamically efficient, but also to reduce the radar signature. As the British began to develop and improve radar technology, the Germans were increasingly aware of the need to defeat its penetrating gaze. The Hortens used a unique glue in their planes, rather than metal nails or rivets; the glue — a carbon composite — and the low profile meant that the aircraft were far harder to see on radar. In 2009, a full-size reproduction of the Ho-229 V3 was constructed for a television documentary. It cost $250,000 (£160,000) and took 2,500 hours to build, but its radar profile was found to be less than 40 per cent of a World War II fighter (such as the Messerschmitt Bf-109). Not only was this a revolution in design, but the plane, had it gone into production, would have been the world’s first stealth bomber.