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Aviation History
1959
1959 - 0820.PDF
20 March 1959 AERO ENGINES 1959 . . . being fitted to the Convair F-106 and RepublicF-105 families. Both engines are equipped with variable afterburners and are stressed for flightat Mach numbers slightly greater than 2. Now coming into production is the J75-P-10, inwhich detail refinements and improvements in material specifications permit an increase inturbine inlet temperature and a slightly greater mass flow. This engine will be fitted to futureF-106s and to the F-105D and E. A rather different unit is the J75-P-2 Navy engine, forthe Martin P6M-2 SeaMaster. JT4 Commercial Most of the Boeing 707and Douglas DC-8 airliners so far ordered will be powered by Pratt & Whitney JT4 com-mercial engines. The version currently in pro- duction for the domestic and internationalDC-8s and the Boeing 707-220 and 320 series is the JT4A-3, corresponding roughly to theP-3 military engine and having a dry rating of 15,500 lb. This engine was awarded anapproved type certificate in 1957 and is scheduled to go into commercial service laterthis year. The price is of the order of $245,000. The A-3 is now flying in both 707sand DC-8s and is reported to be performing well in these aircraft. By 1961 deliveries should begin of theadvanced JT4A-9, corresponding roughly to the J75-P-10. As in the case of the militaryengine, an increase in flame temperature and mass flow permits a considerable increase inboth dry and wet ratings, and maximum sea- level thrusts of approximately 19,000 lb areat present being assumed for the A-9 in current DC-8/B.707 brochures. JT8/J52 Developed originally to a Navyspecification, this engine again adheres to the established J57/75 formula but is scaled downto give an initial thrust of 7,000 to 7,500 lb. Several versions have been planned, both withand without afterburners and with different accessory configurations. The original appli-cation—an advanced version of the Douglas A4D Skyhawk—<iid not materialize, but a con-siderable quantity of military J52s will be required by the Grumman A2F-1 multi-pur-pose carrier-based aircraft and the North American GAM-77 Hound Dog air-to-surfacemissile. In the Hound Dog the J52 will pro- vide cruise propulsion at high subsonic andsupersonic speeds over a range of at least 450 miles. A commercial derivative of the JT8 familyhas been planned and it is logical to assume that a fan version is already under develop-ment. In fact, a pair of JT8 turbofans has been suggested as one of the most attractive pro-pulsion systems for the short-haul jets at present being promoted by Boeing andDouglas. Such engines would probably give about 12,000 lb thrust for an installed weightof less than 2,500 lb and with a very good specific fuel consumption. JT11/J58 Some three years ago Pratt andWhitney Aircraft started the detail design of a wholly new series of turbojets which promiseto form a new generation of single-shaft engines as extensive and versatile as the JT3,4 and 8 two-spoolers. The first of the new family is also the largest, and will probablyremain so for several years to come. As the J58 it has been developed rapidly and success-fully by the company's new research and development centre at West Palm Beach,Florida, under contract from the U.S. Navy. It is the first American engine of whichdetails are available designed for flight at Mach numbers of 3 or more. It follows theappropriate configuration in having a relatively low inbuilt pressure ratio but a tremendousmass flow per unit of frontal area; in fact, the engine can be thought of as a de HavillandGyron designed to take full advantage of recent improvements in the state of the art. Internaldetails remain classified but the compressor apparently has nine stages, the first four beingslightly separated by a circumferential bleed system, the shutters of which can be openedand closed by three actuators disposed around the casing in order to provide improved hand-ling over the very wide range of flight condi- tions encountered. This is a much simplerarrangement than employing variable stators, and represents the logical outcome of therudimentary bleed valves employed on the PT2F turboprop. The high-intensity combus-tion system appears to adhere to the company's established policy in having only eight burners;the turbine almost certainly has two stages and in its present form the engine is teamedwith an afterburner of advanced design ter- minating in a huge con-di variable nozzle. Already several versions have made theirappearance, although the first experimental prototype only ran at the beginning of lastyear. Funding from the Navy is sufficient to have permitted the construction of a batch—suggested to be about 50—of prototype and development engines, and one of the first ofthese completed a very successful 50 hr test in August last year. An appreciable propor-tion of the current running time is taking place with high-energy fuels both in the afterburnerand main combustion chamber. No engine of this family yet has an announced application,although twin J58s may power a new version of the Convair B-58. JT12/J60 Following upon the practiceestablished with the JT3 family, Pratt and Whitney are starting to play tunes upon thebasic geometry of the new generation of single- spool engines. It is fair to assume that theJT11 is the largest member of this new family, and it is equally likely that the JT12 will bethe smallest for a considerable time to come. Pratt & Whitney have scaled this basic layoutto the optimum size of engine for maximum thrust/weight ratio, and they have succeededin reaching the excellent value of 7 : 1. As at present conceived, the JT12 is under develop-ment for military arjd civil applications involv- ing such diverse fields as business and execu-tive aircraft, military trainers, target drones and missiles. The fixed geometry of its single-rotordesign, coupled with its outstanding brochure performance, has already placed it in a com-manding position in the 3,000 1b thrust field (notwithstanding its appearance on the scenea full year after the Fairchild J83 and the G.E. J85). . •..-;. -... - :..... , , ..-.,. .... .\.. .•;•..,. . 409 An indication of the technical strength ofPratt & Whitney Aircraft is the timing of JT12 development: design studies begun, July 1957;detail design started, September 1957; draw- ings released, January 1958; first engine run,scheduled for July 1958, actually achieved May 16, 1958; 50 hr endurance test completedAugust 16, 1958. For unmanned applications prototype engines will be available in July andbulk production could start in June next year. For piloted aircraft, prototypes could bedelivered in October and production deliveries are scheduled to begin in October 1960. Threeof the first transport-type aircraft scheduled to use the engine are the Lockheed Jetstar,McDonnell 119 and North American T-39 Sabreliner. Essentially similar military J60engines may be used by such aircraft as the Canadair CL-41 and possibly a developed ver-sion of the McDonnell GAM-72 decoy missile. With an afterburner, the advanced JT12A-20is initially aimed at operation at flight Mach numbers of the order of 2, and with continueddevelopment is expected to reach Mach 3. Pratt & Whitney have evolved a turbofanversion of the JT12 which they are offering for use in projected airliners and executive air-craft. As far as is known, the engine exists only on paper, but unofficial reports state thatthe thrust would be approximately 4,000 lb and the weight about 600 lb. This could bethe first single-shaft fan engine. REACTION MOTORS ReactionMotors Inc., A Division of Thiokol Chemical Corp., Denville, N.J. In 1947 one of thiscompany's first products, the 6000C4 four- barrel rocket engine, was the first aircraftpowerplant to fly faster than sound. The vehicle was the Bell X-l, and derivatives ofthe 6000 series (military designation LR8) were used in all the X-l aircraft. The pump-fed propellants of these four-barrel engines are liquid oxygen and a mixture of ethyl alcoholand water, and each of the regeneratively cooled Pratt & Whitney JT8 (J52-P-1) Military (GAM-77 missile) two-spool turbojet. Nine-stage low-pressure com- pressor, seven-stage high-pressure compressor, annular combustion chamber with eight flame tubes each with six burners, single-stage h-p. turbine and two-stage l-p. turbine. Max carcase diameter, approximately 34 in; length as depicted, about 118 in; maximum rating, probably 7,500 Ib thrust. The defunct J52-P-4 Navy engine for piloted (A4D-3) application was rated at 7,250 Ib dry with s.f.c. of 0.8; the original J52-P-2, with afterburner, was rated at 10,000 Ib. Most information on the JT8 family remains classified Pratt & Whitney JT11 (YJ58) Military single-shaft turbojet. Axial compressor (almost certainly with nine stages), annular combustion chamber with eight flame tubes, two-stage turbine and large afterburner (not illustrated) with fully modulated con-di nozzle. All details are classified, apart from the fact that max dry thrust is "in the 30,000 Ib class." It can be deduced that overall diameter is of the order of 50in, and dry weight is probably about 5,500 Ib. Max thrust with afterburner (static at sea level) is likely to be about 45,000 Ib.
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