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Aviation History
1959
1959 - 0824.PDF
FLIGHT, 20 March 1959 AERO ENGINES 1959 .' . . for overseas deployment by the U.S.A.F. Strategic Air Command. The chamber of this family of engines is very similar to that employed in the LR89 boosters of the Atlas ICBM, already described, and is identical to the chamber of the engine of the Thor IRBM (the MB-3, illustrated). Almost the only unique feature of the S-3 series is the manner in which the efflux from the gas generator, which drives the twin turbopumps, is expelled overboard from a swivelling nozzle which acts both as a vernier motor and as a roll controller during powered flight. Propellants are liquid oxygen and RP-1, and the specification is similar to that for the MB-3. The first engine was tested in November 1955, the mock-up was delivered in January the following year, production engines began to fly in September 1956 (an R. & D. unit was delivered the pre- vious July), and the Jupiter started its flight- test programme in March 1957. S-3 engines have been fitted to all versions of SM-78 Jupiter IRBMs and to the NASA Juno space- probe vehicles (booster propulsion). The current S-3D is lighter and more compact than the earlier versions, and incorporates simplified starting and control systems. Features include the elimination of airborne starting tanks, a miniaturized pneumatic con- trol panel, a thrust control system and engine-mounted hydraulic systems. MB-3 Almost identical with the S-series of engines for the Jupiter, the MB-3 (Service designation LR79-NA-9) is in quantity pro- duction at the main plant in Neosho and is fitted to the SM-75 Thor IRBM of the U.S.A.F. Strategic Air Command and R.A.F. Bomber Command, to the U.S.A.F. Thor-Able test vehicle (booster propulsion) and to the ARPA Discoverer lunar-probe vehicle (boost propulsion). In all these vehicles the chamber is gimbal-mounted, and is flanked by vernier engines, forming an integral part of the propul- sion system, which provide roll control and establish the final velocity and directional con- trol after shut-down of the main engine. The exhaust-thrust from the turbopump gas-genera- tor is slightly less than that of the vernier system and is discharged from a fixed down- Rocketdyne A-7 Military rocket engine. Single fixed Ciamber fed by turbopump with liquid oxygen and alcohol. External diameter of chamber nozzle, about 33in; overall height of package as depicted, approxi- mately 115in; dry weight, of the order of 1,700 Ib; sea-level thrust at full propellant flow, 75,000 Ib; propellant consumption, approximately 300 Ib/sec. A'.'- 411 Rocketdyne MB-3 (XLR79) Military rocket engine. Single gimbal-mounted chamber fed by turbopumps with liquid oxygen and RP-1. Chamber nozzle dia- meter, approximately 47in; overall height of package as depicted, 144in; dry weight, of the order of 2,000 Ib; "sea-level thrust at full propellant flow, 150,000 Ib; propellant consumption, approximately 550 Ib/sec. ward-facing pipe flanking the main chamber. Work on the MB-3 propulsion system began a few weeks after the Air Force received authority, in November 1955, to produce an IRBM. The first engine of the related Jupiter series was fired in November 1955, a research and development model was delivered for missile-mating firings in June 1956, and the first production model was shipped to Douglas in September 1956. Thor entered the flight- test stage in January 1957, and at the time of writing more than 30 rounds have been launched. Major engine components have been reduced from 46 in the early configura- tions to 28 in the current NA-9 models now being delivered. This achievement stems largely from a simplified starting and control system, which eliminates the airborne start- ing tanks and utilizes a miniaturized control panel. A slightly earlier version of the engine, incorporating airborne starting tanks, is depicted in the drawing. SOLAR Solar Aircraft Company, San Diego 12, California. For more than ten years Solar have been active in the field of gas turbines of diminutive proportions. Some thousands of units have been sold, the most common being the 50 h.p. Mars and the 500 h.p. Jupiter, both of which are widely employed in ground and marine applications (particularly in airborne auxiliary power units). The engine described below is the first to be planned specifically for aircraft propulsion. T62/66 Titan Introduced in the spring of 1958, this extremely attractive unit is possibly the smallest aircraft engine in the world, and certainly one of the smallest gas turbines. It replaces the Mercury described in our 1957 review, and is being developed under a con- tract funded jointly by the Navy Bureau of Aeronautics and the U.S. Army. The basic engine, the configuration of which is given in the data panel, has a centrifugal compressor and a radial inflow turbine mounted back-to-back with a bearing support between them. Hot exhaust gases are kept away from the external surfaces of the engine, and although turbine-inlet temperature is approximately 1,450 deg F no portion of the outside of the engine exceeds 450 deg F. Reli- ability and the need to minimize cost were dominant factors in the design. One of the chief problems encountered in the develop- ment of the Titan was the need to "custom- design" all controls and accessories, those previously on the market being disproportion- ately large. Most of the accessory and control systems had to be designed by Solar to a new standard of miniaturization, and starting is accomplished by a hand crank. The engine is being developed in two quite distinct forms. The YT62 is a single-shaft version designed principally for one-man helicopters. The YT66 is a free-turbine model intended for use in flying platforms, the turbine wheel being divided into two sec- tions to provide independent variation of com- pressor speed and output r.p.m. Pre-flight testing of a YT62 is at present taking place with a unit installed in a one-man helicopter (photograph, February 6, page 176). WESTINGHOUSE Aviation Gas Turbine Division, Westinghouse Electric Corp., Kansas City, Missouri. Since 1941 this huge company has been actively developing axial turbojets, chiefly under contract to the U.S. Navy. One of their earliest designs, the 24C or J34, has proved to be their only real success; the larger J46 and J40 are now out of the picture (the former is in limited service in F7U Cutlasses), and neither of the engines produced as a result of the 1953 agreement with Rolls-Royce has found a production appli- cation. The latter engines are the XJ54 turbo- jet—virtually a scaled Avon 200—rated at 6,700 lb dry thrust, and the XJ81 turbojet rated at 1,800 lb and used in the Radioplane XQ-4 target drone. The agreement with the British company expires in 1961. J34 Some thousands of these reliable single-shaft turbojets are in service in the McDonnell F2H Banshee and other aircraft. Production had ceased when, in 1956, West- inghouse received a contract to develop a new version tailored to the arduous requirements of the Navy's North American T2J-1 multi- purpose trainer. The production contract, worth $26m and awarded in November 1957, came as a welcome shot in the arm, and further "product-improvement" contracts have since followed. The T2J engine is depicted on p. 412, and it differs in having a new compressor, a revised combustion chamber and fuel system to permit unrestricted operation on JP-4 or JP-5 fuels, and in the arrangement of its accessories. W RIGHT Wright Aeronautical Division of the Curtiss-Wright Corp., Wood-Ridge, N.J. For a variety of reasons, this great company have failed to retrieve their position in the field of aircraft propulsion. Current business is centred almost entirely upon the J65 turbojets, of basically British design, and upon the pro- vision of spares and service-support for Turbo- Compounds. Later turbojets, turboprops, ramjets and rockets have all failed to achieve production applications. Notes on the J65 are given on p. 412. The Turbo-Compound, now out of production, is in world-wide civil and military service and has logged many millions of hours, yet its mechanical complexity and the arduous operating conditions of the power- recovery turbines and other portions is such as to make really long overhaul life and trouble- free operation an unattainable goal. The last batches of EA-series engines were priced at around $90,000 and are currently operated to an overhaul cycle of around 1,400 hr. The military-sponsored T47, T49, J67, XRJ47, Solar YT62 Titan Military turboshaft engine. Con- figuration as shown in section drawing. Maximum carcase diameter, 12.5in; overall height, as depicted, 21 in; dry weight, 50 Ib; max rating, sea-level, at 56,700 r.p.m., 55 s.h.p. plus 12 Ib thrust at 100 deg F rising to 70 s.h.p. in low ambient temperature.
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