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Aviation History
1945
1945 - 1810.PDF
284 F LI G HI SEPTEMBER 13TH, 1945 GERMAN JET RIVALRY Whilst it has become almost axiomatictht tile German mentality was never disturbed by complexity of design or pro-duction, this unit, despite its undoubted technical interest, was turned down bythe German Air Ministry. Work on the' project was stopped, 'and later Daimler-Benz were given the task of adapting the Jleinkel oil unit for driving an airscrew.Towards the end of the war the de- velopment of turbo-jet and airscrew com-binations was being actively pursued. , As mentioned, the Heinkel on was tobe adapted by the'Daimler-Benz concern. The designed output at the airscrew was3,300 h.p. at a flight speed of 560 miles per hour. - * • -. The Junkers Company had a projecteddesign based on their 012 unit. This was to be modified by the-provision of gearingtor contra-rotating airscrews and was to be known as the 022 unit. A third example, also an uncompletedproject, was a conversion of the ambitious B.M.W. 018 unit to drive contra-rotating airscrews. An additional stage was addedto the turbine, making a total oi four, and the drive was taken oil the compressor shaft and transmitted through planetarygears. It was expected that 7,700 h.p. would be delivered to the airscrew shafts. A Jet—propelled Bomber Foi short-range operations the jet-propelled bomber wasattractive by reason of its high speed. However, owing to difficulties created by the Allied bombing programme, only oneaircraft actually became operational. This was the high-wing Arado 234B, a light bomber and reconnaissance type, firstdown in December, 1943. Developed from the experimental Ar234A which had a jettisonable undercarriage, it had a wingspau of. 47ft. and a take-ofi weight of 18,500 lb. which could be increased to 22,000 lb. with rocket take-off. Two Junkers004 jet units were underslung from the wing,' and tank capacity was 836 gal. As a reconnaissance craft it had a maximumspeed of 470 m.p.h. at 18,700ft. and a service ceiling of 37,700ft. Normal bomb load was 2,200 lb., but a maximum load of4,400 lb. could be carried. As bombs were slung externally the maximum load reduced the speed by about 60 m.p.h. More interesting was the 234C. This was the 234B withslight modifications and powered by four B.M.W. 003 jet units arranged in two twin nacelles under the wing. It only reachedthe prototype stage, but had been proved to possess good inherent stability in addition to a high performance. Rate ofclimb was 3,600 ft./min. with a maximum level speed of 5-)G m.p.h. at 20,000ft. and a service ceiling of 37,800ft..Endurance was 40 min. at full thrust or 85 min. at 60 per cent, thrust, but these figures could be improved by theemployment of drop tanks. The first jet-propelled heavy bomber ever to fly,.again onlyas a prototype, was the Ju 287. It was exceptional in having Artist's impression of the Messerschmitt Me 264 long-range bomber. a wing form which swept iorward at approximately 25 dog.,presenting a very unconventional appearance. This feature was claimed to be oi advantage aerodvnamically and to improveDandling characteristics at low speeds. The span is 66ft. and the total wing area 628 sq. ft. Carrying a load of 6,600 lb.oi bombs, it had a range of 1,175 miles and a maximum speed at 16,400ft. of 537 m.p.h. The maximum bomb load whichcould be carried was 9,900 lb. It was. initially designed to be powered by two large turbo-jet units, either Junkers 012 orB.M.W. 018. As these units were not ready for installation, various arrrangements of four or si.\ smaller jet units alreadyin production were employed. In some instances all the jet units were mounted under the wings, either singly or in groups,whilst in others one unit was mounted on each side of the fuselage nose and the :emainder slung under the wings. Power Boost Schemes The Germans displayed considerable interest in schemes forobtaining a sudden burst of power for short periods. This is understandable in view of their tactical requirements. In thecase of interceptors, extra power was necessary to increase the rate of climb, fighters needed it for evasion, and bombers fortake-oft. In most cases their machines required a temporary margin of performance to give them a reasonable chance ofsurvival against the attacks of Allied aircraft. Apart from, ingenious methods of boosting power by the injection ofmethanol-watcr, ethanol-water, pure water, and nitrous oxide gas into the eye of the supercharger and the injection of petrolinto the air intake, they aimed to utilise liquid rocket and turbine jet units for this auxiliary service. The most interesting example of this was the Me 264 long-range bomber with which it was ultimately hoped to raid New York. This was a most promising design, somewhat resemblingin outline a large Liberator. It had a wing of exceptionally high aspect ratio with a span of 141ft. Armament and equip-ment were sacrificed in order to attain maximum range, and to support its tremendous weight at take-off a pair of extrawheels were provided which were jettisoned as soon as the craft became airborne. It was first flown in December., 1942,but fortunately it was never developed beyond the prototype stage. For test it was fitted with four Jumo2ii engines, butJumo2i3 or B.M.W. 801 were intended for installation. For short period'bursts of high speed, two B.M.W. 003 jet unitswere to be provided, one under each main plane. Similarly, Focke-Wulf also had a design for a six-engined'bomber, the Ta4oo, which was handed over to S.N.C.A.O. in Paris for development. PARTICULARS OF THREE GERMAN JET UNITS K_ Experimental Daimler-Benz unit on test. Sea level staticthrust, lb. Weight, lb. Overall length, ft...Max. diameter, ft... Sp. consumption. lb./hr./lb. thrustFull thrust speed . . BMW 003 1,760 1,250 11.6 2.26 1-479,500 r.p.m. JUMO 004 B 1,890 1.585 I2.72.64 *-48,700 r.p.m. HEINKEL- HJRTH 00J 2,860 2,090 II.5 2.87 11,000 r.p.m.
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