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Aviation History
1960
1960 - 0384.PDF
384 FLIGHT, 18 March l%0 Aero Engines 1960 Pratt & Whitney JT12A-6 Commercial turbojet.Nine-stage compressor, annular combustion chamber with eight flame tubes and two-stage turbine.Overall diameter, 21.9in; max height, 27.8in; length as depicted, 74.2in; dry weight 430lb bare; maxrating 3,000lb with s.f.c. of 0.950; max cruise, 2,1401b with s.f.c. of 0.890.JT12-A-20 (J60-P-1) Military turbojet with after- burner. Overall length, 126in; dry weight, 6511bbare; max rating, 3,9001b with s.f.c. of 2.30 or 1,8001b at M0.9 at 35,000ft or 3,6501b at M2.0 at 35,OOOft. i1 — — Pratt & Whitney JT3D-1 Commercial turbofan.Two-stage fan, six-stage low-pressure compressor, seven-stage high-pressure compressor, combustionchamber with eight flame tubes each having six burners, single-stage high-pressure turbine and three-stage low-pressure turbine. Max diameter, 53.05in; basic length, 145in; dry weight, 4,0251 b; max rating,17,0001b at 8,200 r.p.m.; max cont rating at 300kt at sea level, approximately 10,0001b; estimated cruiserating at 36,000ft at 500kt. 4,0001b with s.f.c. of 0.79. are turboshaft engines for helicopters. Spon- sored in the autumn of 1957, these have since evolved very successfully from an initial T55-L-3 rating of 1,850 s.h.p. During the first half of 1959 bench running of the L-3 indicated that this rating was con- servative. On May 25 Lycoming were able to announce that an engine rated at 1,940 s.h.p. was to be developed as the powerplant of the big Vertol YHC-1B Chinook helicopter. On August 10 the company announced the success- ful completion of a 50hr preliminary flight rat- ing test, as a result of which the engine was uprated to 1,900 s.h.p. The test demonstrated a 5 per cent reduction in s.f.c. and a 61b reduc- tion in total weight; the average output was 2,090 s.h.p. and the maximum recorded was 2,160. The following month the L-5 was ap- proved at 1,940 s.h.p., and during further development for the Chinook power was raised until last month it was announced that the L-5 now has a military rating of 2,200 s.h.p., and over 2,500 s.h.p. has been reached on the bench. Deliveries to Vertol should be made in August. This increased rating makes possible a turboprop with a take-off rating of 2,300 s.h.p. and a military rating of 2,150, and growth potential should make possible the achievement of 2,700 s.h.p. with a further reduction in s.f.c. Power/weight ratios on these advanced models will approach 5 h.p./lb. The L-5 is a high-speed version with an integral oil tank and cooler replacing the front reduction gear. The L-l turboprop incorpor- ates a 10.24:1 planetary reduction gear mounted centrally within the intake. The hydro-mechanical control system incorporates governors for both the gas producer and power turbine. In the turboprop the power-turbine governor prevents overspeeding in the event of propeller failure while in the helicopter engine the same governor becomes the primary con- trol. Other features are a fuel pump with two elements each capable of supplying the full flow, an annular combustion chamber folded back to provide five layers of steel around the turbine wheels, and an all-steel-bladed axial/ centrifugal compressor of robust design. O-360 Introduced in 1958, these flat- fours are in large-scale production in aero- plane and helicopter versions. The vertical- crankshaft VO-360-A1A (Brandy helicopters) and the horizontal O-360-C2B (Hughes 269A helicopter) received the first type certificate to be awarded by the FAA following the forma- tion of that body last spring. Both are rated at 180 h.p. and weigh 2981b including starter and generator. The basic O-360 is being supplied to Piper, Beech, Mooney, Colonial, Call-Air and several overseas firms, including Saab. A direct- injection O-360 powers the Rheem USD-2 drone. O-S40 Also introduced in 1958 was a family of flat-six units of 540 cu in, including a 250 h.p. aeroplane model and a 310 h.p. verti- cal helicopter engine. Very large numbers of both have been made, for such aircraft as the Aero Commander, Piper Comanche and Hiller 12E. PRATT & W H IT N E Y Pratt & Whitney Aircraft, Division of United Aircraft Corp, East Hartford 8, Connecticut. Keenly aware of the fact that they will never again receive orders for thousands of engines at a time, and that their diminishing aircraft markets are being fought for by worthy foemen—especially GE and Rolls-Royce—Pratt & Whitney have nevertheless continued to thrive upon their excellent engineering and great commercial acumen; and at the same time they have put a large foot inside the door to the space age. During the past year the JT3 and JT4 Turbo Wasps have gone into world-wide service in Boeing 707s and Douglas DC-8s. These engines have flown 500,000 hours since scheduled services started in October 1958. They have established numerous route records and demonstrated their ability to perform with reliability at an exceptional intensity of utilization. It was a clever move on Pratt & Whitney's part to add a front fan to both the small and large Turbo Wasps and so produce engines which, although fundamentally slightly less efficient than the optimized units soon to come from Rolls-Royce, can improve the perform- ance of important military and commercial air- craft by a substantial margin. Notwithstand- ing the diminished market for military turbo- jets, new engines in advanced development—one very small, the other very large—can on paper surpass all their competitors. A major share in the design of the small one (the JT12) was entrusted to Canadian Pratt & Whitney, and an entirely new engine by this company is described in the section dealing with Canada. In the field of rocket propulsion Pratt & Whitney's policy of letting others tread the path first, and of then entering the field with something which can beat the lot, appears likely to achieve its customary success. Merely by concentrating upon the technology of liquid hydrogen, the company stand on the threshold of business which may eventually enable them to surpass even Rocketdyne, acknowledged leader in the field of big liquid rocket engines; but such work falls outside the scope of this review. More relevant is the continuation of the P & WA nuclear work, which began with USAF study contracts for a nuclear aircraft engine in May 1951. Since our last review a year ago the Navy's Bureau of Aeronautics have awarded the company a contract worth some $2m to develop hardware. It was the Navy's first such contract, and the compoj- ents are linked with the requirement aad authority of that Service to develop a second- ary heat-transfer system for an indirect-cycie engine. The contract followed a previous re- search study for BuAer which established the feasibility of the company's design proposals. Since 1953, Pratt & Whitney Aircraft have also undertaken basic nuclear studies and develop- ment work on advanced reactors, under con- tract to the Atomic Energy Commission. All this work is based at the USAF-owned air- craft nuclear engine laboratory at Middletown, Connecticut. Although the company's design and produc- tion effort remains centred at East Hartford, the new Florida research and development centre at West Palm Beach made an impres- sive contribution during the past year, hand- ling the advanced JT11 (J58) family and most of the rocket work. Six new test cells were added to the Willgoos Laboratory during the year (this single facility is now valued at $50m), and employment at the start of 1960 was approximately 36,500. JT3/J57 After manufacturing turbojets of Rolls-Royce and Westinghouse design, Pratt & Whitney roughed out this big two-spool turbojet in 1947. By 1949 the design was com- plete and production began in February 1953. Since that time more than 17,300 military J57s have been delivered to the US Air Force and Navy, some being manufactured by the second-source established by Ford in Chicago. Last year 1,757 were delivered, and total mili- tary hours exceed 6m. Most of the non-after- burning J57s are used in Strategic Air Command B-52s(all versions), KC-135 tankers, and North- rop Snarks, and in Navy A3Ds; in the B-52 they have on occasion reached the brochure over- haul period of l,400hr. The afterburning fighter engines are usually pulled every 200hr. A J57 is currently being modified to provide shaft-power for industrial applications. In co- operation with Cooper-Bessemer, Pratt & Whitney have arranged for a J57 to exhaust through a C-B turbine extracting up to 10,500 s.h.p. One assignment will be the cross- country pumping of natural gas, and the engine has been modified to use the gas as fuel. JT3 commercial Notes on the inception of the airline version of the JT3 were given in our 1959 review. Most engines in current service are of the C-6 sub-type, equipped with a fuel/air (rarely electric) starter, bleed-aii anti-icing, bleed-air drive to remote turbo- compressors for cabin pressurization and a combined thrust reverser and multi-pipe final discharge unit. Most operators have recorded cruise consumption for a 707 or DC-8 at 1,680 to 2,080 Imp gal/hr. In the first year of service, ending last October, unscheduled engine changes resulting from "primarv causes" (in-flight failure) amounted to 0.21 per l,000hr, while secondary causes resulted in 1.41 changes per l,000hr. Unscheduled changes amounted to 12 in 92,264hr flying, and 40 after 300,000hr. Most C-6s are cur- rently operated to a life of l,000hr, but have to be pulled open at 500hr. Last September deliveries started on the JT3C-7, distinguished by a weight-reduction of no less than 7501b, chiefly by a major re- design of the carcase. Although in all other respects performance is substantially im- proved, removal of the water-injection system has cut the average take-off rating by 1,0001b. By the summer of this year the JT3C-10 and C-12 will become available, these being essen- tially the same as the C-7 but fitted with water injection to restore the 13,0001b take- off rating. List price varies between $150,000 and $160,000. JT3D/TF33 In January 1958 Pratt & Whitney started the detail design of an engine which, although based upon the JT3/J5". incorporates a forward fan in order to handle
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