NAZI AIRCRAFT

Evening Post, Volume CXL, Issue 150, 22 December 1945, Page 5

NAZI AIRCRAFT

Technical progress

LEAD IN JET PROPULSION

The account prepared by the technical experts of the Air Ministry and Ministry of Aircraft Production of wartime developments in Germany of aircraft, aero engines, aircraft armament, jet-propulsion, and liquid rocket propulsion units, and engine power-boost-ings systems is a most revealing document, says the aeronautical correspondent of '"The Times." Not only does it show that Germany, and not Britain, was the first country in the world to fly a jet-propelled aeroplane—it had previously been thought that the Whittle-propelled E2l/39 Gloster machine was the first to fly—it also shows beyond any doubt that in the early development of this revolutionary new form of power-plant the Germans led the world.

The Luftwaffe was the first air force to be given a jet-propelled fighter, a jet-propelled heavy bomber, and a jetpropelled dive-bomber. German technicians had also started to develop a composite aircraft in which both the upper and lower components were powered by "jets"; a Junkers "flying wing" type of machine propelled by four jets; and a single-seat fighter of the tailless type, also jet-propelled. A helicopter with jet-actuated rotor had even been experimented with in Austria. Some of the new types of aircraft were intended to use the •'straight" jet (such as employed in the British-made Gloster Meteor), while others made use of the turbo-jet airscrew combination.

Altogether 19 types of jet-propelled aircraft had been flown or were being developed when the collapse came, as well as six types of rocket-propelled machines. In more than one case jetpropulsion engines were reinforced by liquid rocket units to give greater speed for the take-off and initial climb; one of these machines, the Focke-Wulf Ta 183, the most recent project of. Professor Kurt Tank, had a maximum speed of 590 miles an hour and an endurance of three hours. Another jet fighter, known as the Volksjaeger (People's Fighter), which was designed to employ as little as possible materials which were scarce, had an explosive cartridge arrangement by which the pilot could be shot out through the opening over the cockpit in case, of emergency. Even this machine had a top speed of 522 miles an hour. The Heinkel 178, the first jet-propelled aeroplane in the world to fly, was testflown just before the outbreak of war —in August, 1939.

SPEED AND ARMAMENT. In all their work on a variety of aircraft types ■ the Germans showed considerable ingenuity, and after reading a detailed account of their experiments one can only conclude that but for the damaging effect of the Allied bombing offensive, a scarcity of some metals, and an inadequate labour force the Luftwaffe would have remained a most formidable opponent to the end of the war. Even their orthodox fighters were reaching maximum speeds not much under 500 miles an hour. For aircraft armament they had developed guns of 50mm calibre; the biggest gun disclosed as having been used on a British aeroplane was 40mm. Remote control gun firing and periscopic sights were also introduced. The tremendous amount of experimental and development work in Germany on the V weapons (flying bombs and rockets), on jet-propulsion and liquid rocket-propulsion, was not allowed to impede great progress along orthodox lines. The biggest piston engines mentioned in the official list developed 4000 b.h.p., which is more powerful than any British aero engine announced to date. One of these powerful engines was arranged to drive four-bladed contra-rotating airscrews, and one was fitted with a twostage, four-speed supercharger; another had a three-stage supercharger. The speed of some machines could be increased by the use of an ingenious method of "boosting" the power output of engines by the injection of a mixture of methanol and water or another mixture. On the Messerschmitt 109 fighter the system was used to obtain extra power below the rated altitude of the engine. The mixture was injected into the intake side of the supercharger and acted .as an antidetonant, providing a charge cooling and enabling higher boost pressures to be used.

Another power boosting system, first referred to by the Germans as "ha ha" (presumably because it employed nitrous oxide or "'laughing gas," which is injected into the supercharger), was used above the rated altitude of the engine. The nitrous oxide provided additional oxygen for the engine, as well as acting as an anti-detonant. Another "boost" device injected petrol into the air intake to increase the emergency performance of the engine; it temporarily added some 140 h.p. to the power output of the engine. Early in the war the Germans had made sufficient progress with various forms of jet-propulsion to need an elaborate code system to distinguish between rockets, turbo-jets, airscrewturbine units, propulsive ducts (known as Athodyd, or "ram jet"), intermittent propulsive ducts (used in the flying bomb), and a combined rocket and Athodyd. Preliminary work on jet-propulsion was started by Bayerische Motorenwerke as early as 1934, and the company produced its first completely satisfactory unit in August, 1940. One of its units delivered 7700 h.p. (o the air-screw, and the equivalent horse-power developed at 500 m.p.h. was 14,000. The Junkers concern did preliminary jet-propulsion work in 1937, and at the end of 1939 designed a full-scale turbo-jet. Largescale production was planned to start in the summer of 1943, but was not fully achieved until May or June of 1944. A Junkers Jumo turbo-jet unit was patiently developed until it gave a fighter a speed of 560 m.p.h. at a height of 36,000 ft. Another Junkers Jumo unit, intended for a fast bomber, had an 11-stage compressor system and a two-stage turbine.

ROCKETS FOR DEFENCE. In a "last ditch" attempt to stop the Allied heavy bomber attacks the Germans decided, towards the end of 1944, to produce a cheap, semi-expendable, rocket-propelled interceptor of very small endurance to deiend specific vita] targets. It was to be midway between a directed missile and an interceptor fighter in method of operation, the sole duly of the pilot being to control the small aeroplane during the last few hundred yards of its flight towards a bomber formation. The initial flight was to be directed from the ground, guided by data supplied from radar detectors. Fitted with a liquid rocket unit, the machine, the

Bachem BP2O, was to attain a maximum sp.eed of over 600 m.p.h. at 16,000 feet, and the initial rate of climb, helped by auxiliary take-off units, was calculated as more than 37,000 ft per second. To economise in expensive rocket units it was intended to return to earth by parachute the rear portion of the fuselage housing the power unit, allowing the remainder of the aircraft to crash when the pilot had baled out immediately, after making his attack. This project had. reached only an early stage of development when the war in Europe ended. The squat-shaped Messerschmitt 163 was the first operational aircraft in the world to be powered solely-by rocket motor. The weight of the power unit was only 3651b, and it developed a thrust at sea level of 33001b. Unlike the reciprocating engine, the liquid rocket motor gives increased, rather than decreased, power at high aititudes; at 40,000 ft the thrust of the Me. 163 was about 10 per cent, greater than at sea level. The fuels employed are known as T-Stoff, which is concentrated hydrogen peroxide, and C-Stoff,. which is a mixture of hydrazine hydrate and alcohol. In addition to its use as a fuel, C-Stoff was employed to cool the double-walled combustion chamber. The two fuels were contained in separate tanks and were delivered to the combustion chamber jets under pressure from two turbine-driven pumps. Only a fraction of the full "thrust is required to maintain a fairly high speed in level flight, but because the efficiency of the rocket motor falls off rather rapidly under conditions of partial thrust a second unit was developed, containing main and auxiliary combustion chambers. Both could be used together to give a total thrust of 44001b, but for cruising only the small chamber was employed."

NEW HELICOPTERS. A German helicopter was first flown in 1940, and towards the end of the war interest in this type of aircraft had increased considerably. One flown in 1940 had an all-up weight of 86001b, and could carry a useful load of 7760 lb. A more ambitious project, which was never completed, would have weighed 33,0001b. The Fa 330, which was built to co-operate with U-boats, was not, strictly speaking, a true helicopter, but an unpowered rotor-kite. The velocity of the air caused the rotor to turn as the kit was towed along by a U-boat travelling on the surface, and gave lift to the kite, which was connected to the submarine by cable and winch. The observer, sitting in the kite, had controls for operating a rudder and for tilting the rotor head, and he could communicate with the U-boat crew by telephone. Tricycle undercarriages were becoming general practice in Germany toward the end of hostilities,- while pressure-cabins had been developed not only for high-altitude fighters, but also for bombers and reconnaissance machines. Big strides had clearly been made in the development of contrarotating airscrews (two sets of blades on,the same hub, rotating in opposite directions to give more efficient absorption of engine power and to counteract what is known as torque, or swing). Germany had also built two prototypes of a six-engined Blohm and Voss flying-boat which weighed 198,000 lib. They had a .-span of almost 200 ft (not far short, of \-, twice that of the. Lancaster a;nd .Halifax four-engined bombers). "> A""'Blohm and Voss troopcarrying transport flying-boat designed to accommodate 110 soldiers and a crew of 11, could cruise at ISS m.p.h.. had a "ceiling" of 26,000 ft, and an endurance of between 19 and 20 hours. A four-engined Arado troop-carrier had 11 pairs cf wheels on to which the machine could be lowered for loading or to help it in moving over rough ground. _______________