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Pratt & WhitneyJFTDI2

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1024 FLIGHT International, 28 June 1962D O D ; Boeing were given a paid study contract to switch from the GEMF295 (q.v.) to the TF 30. Although bigger and heavier than the otherengines considered, the TF30 was a Pratt & Whitney product, and thisappea rs to have been a major factor in its selection. The engine is thusnow a focal point in what will probably become the largest aircraftprogramme in the US, and total engine purchases are expected to reach$800m over eight years. The manufacturer's designation for the TFXengine is JTF10 A-20. Installed in the Air Force F-111A it is expectedto weigh about 3,5501b with afterburner and v ariable nozzle, but withou tany deflection system (which was not asked for). De tails of the engineare classified, but it is said to have a zero stage on the fan and to berated at approximately 12,0001b dry and 19,5001b with reheat in bothhot an d cold flows. It is thu s very closely related to the TF -106 . SeveralJTF10 experimental engines are running, and one has flown under aB-45. The A-20 version has yet to be built, and it is anticipated that itwill need about two years to bring it to the production stage.JT11 Financed by the Navy as the J58, this single-shaft turbojetis in the 30,0001b class and is specifically designed for cruising Machnum bers over 2.5. A numb er of experimental units have been run atWest Palm Beach, and although this engine is no longer an activeproject it has been instrumental in the development of supersonic-transport propulsion systems.

The first bench run of a prototype engine was originally scheduledfor April 1961, but was delayed until late May . Th e first 150hr test wasannou nced in Decem ber, when total running exceeded l,000hr. Flighttesting was due to begin last autumn, with an engine slung beneath aB-45, but the start of such flying has yet to be announ ced. In spite ofthis delay, and of fairly severe stalling experienced in the h-p compressor,the overall programme is approximately on schedule, with about tenengines having now logged well over 4,000hr. Simulated a ltitudetesting in the Willgoos laboratory has yielded better than the estimatedperforma nce. Prototy pe deliveries to Boeing for airframe testing aredue this year one is already flying, hung on the rear of the "-80"' andproduction deliveries are scheduled for 1963 (originally "in the firsthalf" of 1963). Pratt & Whitney are looking for further commercialapplications, and are especially considering the Caravelle 10B and theBAC One-Eleven (for which they have proposed a derated JT8D).List price of the JT8D-1 is due to rise from the current 8210,000 to8231,000 by 1965.

Military JT8D Although proposals have been made to the USGovernmentsome, one would think, with jet deflection along the linesof the Pegasusthere is no announ ced application. Earlier this mo nth ,however, the JT8D was chosen as the basis for the powerplant for theSwedish Saab-37, and this is discussed on page 1013.JTF10 Today one of the most important aircraft engines inAm erica, this turbofan has a long and chequered history. The basicdesign incorporated major puts of the JT8 (J52) turbojet, and wasevolved in 1957 to meet anticipated commercial and military requirements. The first detail investigation began in 1958, in which yearDouglas chose the JTF10A-1 as the powerplant of the projected DC-9four-engine short-haul airliner. The A-l was a flat-rated unit delivering8,2501b at up to 90F, with promised growth to 9,5001b on a standardday. Durin g 1959 Doug las agreed the use of a full-length ann ularby-pass duct and reverser, and the dry weight of the bare engine cameout at 2,1101b.The first run of a prototype engine took place in that year, and prototype delivery was then scheduled for April 1961. Despite the lapse of

this application, development of a commercial JTF10 has continued,and the most important version at present on offer is the JTF10A-6,some figures for which are given in da ta table 2. T his p owe rplant isspecified for the D ouglas 2086, and is available for the BAC One-Eleven.In each case the engine is started by its 40kVA alte rnator and c.s.d., an dexhausts throug h a pneumatically actuated reverser. L-p bleed air isused directly for cabin pressurization, and the same air is temperedwith an h-p bleed for ice protection.Military TF30 By 1960 the US Navy had welcomed the JTF10as the ideal high-pressure engine for the subsonic Missileer, the carrieraircraft for the Eagle missile. When this weapon system w as cancelledin April 1961, the Navy continued to finance the 10,0001b TF30-2turbofan, and are said to have injected about $30m to date. At the sametime the engine appealed greatly to SNECMA, United Aircraft 'sFrench licensee, who were seeking a propulsion engine capable of compet ing in the forthcoming NA TO V/STOL competi t ions. Prat t &

Whitney have since collaborated with SNECMA in the development ofthe TF-104 and TF-106 (q.v.). Meanwhile the US armed forces wereformulating their requirements for a new "all can do" tactical fighterand strike aeroplan e, and the TF X com petition was instituted. Afterone of the largest battles ever fought by the US aircraft industry theDepartment of Defense last January chose the entries submitted byGeneral Dynamics Forth Worth and The Boeing Co Wichita. GD hadbased their submission on the TF30, and this was the engine chosen by

JT12 Designed by Canadian Pratt & Whitney, this single-shaftturbojet has proved itself a most competitive unit for light military andexecutive aircraft. First run in May 1958, it com pleted its 150hr qua lification 16 mo nths later and has been in production a t Hartford for twoyears. Although a supersonic afterburning version is available, theproduction applications are for non-reheat engines in the T-39/T3JSabreliner, C-140/JetStar and the Fairchild SD-5 dron e. Price of theJT12A-6 is $69,000, and the 3,3001b A-8, specified with SNECMAreverser for the Mystere 20 transport, is 880,000. The same gas producer is used in the JFT D1 2. Military designation of the engine is J60.JFTD12 By adding a two-stage free power turbine at the rearof the JT12 turbojet Pratt & Whitney have evolved a turboshaft unitwith a very competitive brochure performan ce. This performance h asbeen confirmed by bench testing over the past two years, and on May 9the engine flew as the powerplant of the Sikorsky S-64 Skycrane. Tw oJFTD12s are geared to the helicopter rotor system, with their exhauststurned ou tboar d. The industrial FT12 is rated at 3,000 s.h.p.

U S S RIt is not generally realized that about a dozen types of Russian engineare in daily use in Western and "neutral" countries, including the19,1801b RD-3 (AM-3M) turbojet, the 4,015 e.h.p. AI-20 turboprop,and man y types of piston engine. In recent weeks considerable interesthas centred around the decision of the Indian Government to consider the VK-7 turbojet, developed under the leadership of VladimirKlimov, as a possible powerplant for the developed M2 version of theHindustan HF-24 fighter. The VK-7 is said to be a development ofthe VK-5 (M-205), which is rated at 6,5001b dry and 8,8181b with reheat.The VK-5 powers the Mig-19 and Yak-25 supersonic fighters, and itstotal produc tion mu st exceed 20,000 engines. The VK -7 is not knownto have been used in any specific Russian aircraft, although it may wellbe fitted (with centrebody intakes) in supersonic attack machinesclearly derived from the original Yak -25. With a diameter of some 33in,the engine is almost installationally interchangeable with the Orpheus,but Indian technicians are reported to have suggested a series of modifications as a result of studying several VK-7s which were shipped toIndia earlier this year. According to one source, the proposed mo difications would require 18 to 24 months to effect.Soviet Aviation Day last July provided a glimpse of the supersonic"Bounder" prototype, with four engines arranged with direct pitotintakes. The inbo ard engines of this aircraft are estimated to be ratedat some 30,0001b dry and 45,0001b with reheat, and are probablyversions of the Soloviev D-15, rated at 28,6601b. On the same occasionthe Kamov Vintokryl convertiplane was seen for the first time, and therecent speed-record submission to the FAI describes it as being poweredby a pair of 5,700 h.p. TB-2 turboshaft engines, geared to both thepropellers and rotors with the free-turbine output from both enginesinterconnected. In contrast, the TB-2BM engines of the even largerMi-6 helicopter are rated at only 4,635 s.h.p.There have been unofficial reports concerning the turboshaft enginesfitted to the new Mil V-2 and V-8 helicopters, but none appears tobe reliable; photographs suggest that the V-2 has two engines of about500 s.h.p. and the V-8 a single engine of abo ut 3,000 s.h.p.No reliable details are yet available on the turbofan engines of theTu-124 and Tu-124A airliners, although it is suggested that they areSoloviev units rated at 8,5001b. The engine of the An-24 , now com inginto service, is the 2,500 s.h.p. AI-24, and preliminary informationsuggests that it is a single-shaft axial unit. Finally, L'yulk a has p roduced a turbojet weighing 50.71b and rated at 1211b thrust, which isflying in the An-13 sailplane.