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Aviation History
1946
1946 - 1014.PDF
522 FLIGHT , 1946 ROCKET FIGHTERS minutes. Six 30 mm low-velocity, high-capac ity guns (M.K.108) were specified. The second design, the first jet fighter to fly with supplementary rocket propulsion, dif- fered essentially from the standard 262 in having two B.M.W. 003R combined turbine and rocket units. The 003R comprises a standard 003 gas turbine unit of 1,760-2,400 lb thrust, according to mark, with a B.M.W. 718 nitric acid rocket weighing 180 lb, and giving • 2,750 lb thrust for three minutes, mounted on its rear end and faired into the same nacelle. A special drive is transmitted through a shaft to the rocket-fuel pumps, which require 150-200 h.p. The 262 Heimat- schutzer with twin 003RS was estimated to climb to 28,000 ft in two minutes, and sufficient fuel was to be carried for an endurance of one hour at 30,000 ft. When the rocket-fuels were exhausted at 28,000 ft the climb could be continued for another 3,000 ft with a com- bination of inertia and turbine-jet thrust, after which the turbine-jets alone would operate. Having thus attained a high speed and high altitude for the expendi- ture of comparatively little turbine-jet fuel, the machine could then consume the remaining fuel under optimum conditions for maximum range. The rockets could be cut in or out at will, but special control arrangements were necessary to avoid unequal thrusts and a resulting spin. Turbine-cum-Rocket Projects Although development of turbine-cum-rocket fighters was primarily a Messerschmitt concern, Arado and Heinkel had projected variants of the Ar 234 and He 162 (Volks- jaeger) using the dual-purpose B.M.W. 003R. The 234 was to retain two standard 003 turbine-jets in addition to a pair of "R" units, and with full thrust was to climb to 36,000 ft. in three minutes. The climb of the rocket- assisted 162 should have been slightly better, and endur- ance was estimated as 45 minutes. In 1944 Kurt Tank, ot Focke-Wulf, had considered a twin-boom fighter similar to the Varnpire, with one or two liquid rockets to supplement the Heinkel-Hirth gas-turbine, but abandoned this project in favour of a design which be- came the Ta 183, likewise adaptable for a supplementary rocket.# Pure-rocket fighters pro- jected or under development in Germany were of three classes —non-expendable intercepters (Me 163, 263 and P.1104, " Julia " and "Walli ") ; semi- expendable intercepters ("Nat- ter"), and what may be termed special-purpose fighters (e.g., Arado miniature and Zeppelin rammer). Only the Me 163 (sub-type B) became operational. The 163 was basically a Lip- pisch design, and although developed at the Me works was never favoured by Messer- schmitt himself ; in fact, quar- rels over this machine led to estrangement of the two de- signers. At first it was pro- duced as a glider (163A) and " Natter '' on the rails of itslaunching framework. The four A.T.O. rockets are clustered round the tail. The miniature Arado rocket fighter was to be launched by an Ar 234 towed behind an Me no. A re-design, with an early Walter rocket, became the 163B, which was ordered in quantity anfl saw action against American day-bomber formations in 1944, though operations were restricted by the bombing of T- and C-Stoff plants. A 163B is now on view at the Science Museum, South Kensington, and those who missed it at the R.A.E. demonstration will do well to examine it. It will be seen that the swept-back wooden wing has a marked wash-out of incidence toward the tip and, in addition to the elevons '', carries large fabric-covered trimming surfaces. The metal fuselage is made in two halves, the rear part, housing the H.W.K. 509 rocket, being detachable. The 163B takes off under the power of its own rocket on a twin-wheel undercarriage, which is jettisoned auto- matically when the landing skid between the wheels is retracted. About 226 gallons of T-Stoff and no gallons of C-Stoff is carried in wing and fuselage tanks, and weighs 4,450 lb, accounting for nearly half the all-up weight. Two 30 mm M.K.108 guns with 60 rounds each are mounted in the wing roots. In service the 163B was limited to a speed of 550 m.p.h. ; compressibility at higher speeds initiated a sudden dive. The restricted fuel capacity and lack of a pressure cabin limited the ceiling to 40,000 ft, which height' it attained in under four minutes, and the range after climb was 22 miles at 495 m.p.h. Although en- durance could be protracted by periods of gliding, the Germans recognized that it was quite inadequate, and the H.W.K. 509C rocket, with a cruising chamber, was devel- oped for the Me 163C, giving an endurance under power of 12 minutes. A slightly larger machine than the B sub-type, this model weighed over 11,000 1b and had a pressure cabin, permitting a ceiling of about 52,000 ft. The maxi- mum designed speed was 590 m.p.h. In order to leave Messer- schmitt free to concentrate on the 262, development of the 163 was passed to Junkers, who re-designed the sub-type C as the 263, with a slimmer fuselage and retractable tri- cycle undercarriage. It was found possible to provide tankage for about 530 gallons of fuel in eight wing and fuselage tanks, which it was necessary to empty in strict order to minimize e.g. varia- tions. The fuel weighed
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