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Aviation History
1959
1959 - 0810.PDF
20 March 1959 403 probably bore, 106 Ib; guaranteed performance, max rating (up to 100 deg F), seo-level, static, 250 s.h.p. at2,000 propeller r.p.m. with s.f.c. of 0.70 at 59 deg F rising to 0.73 at 100 deg F;75 percent power, 159 s.h.p. with s.f.c. of 0.81; military rating at 6,000ft, static, 59 deg F, 206 s.h.p. with s.f.c. of 0.72. Allison 59I-DI3 Cairnarcial single-shaft turboprop. Fourteen-stage compressor, can-annular combustionchamber with six flms tubas and four-stage turbine. Overall width. 27in; max overall height, 36in; length as depicted, 145.2in; dry weight, bare, 1,750 Ib; max rating, 3,'46O s.h.p. (3,740 e.h.p.) at 13,820 r.p.m. with massflow of 39 Ib/sec, praisjr; ratio of 9:1 and s.f.c. of 0.54; max cont. cruise rating at 25,000ft at 360 kt 1,850 s h p (1,905 e.h.p.) also at 13,820 r.p.m. with s.f.c. of 0.46. entry, the Model 250, was not only technicallyoutstanding, but was also the only one whose sponsor was willing to bear all developmentcosts in excess of a relatively small sum (reported to be $4m). A joint U.S. Army/U.S.A.F. development contract was announced last June 25. The military designation is T63. In all small gas turbines, manufacturingcosts have virtually precluded the adoption of an axial compressor. Allison have evolved amethod by which complete axial stages, blades and all, can be precision cast in an aluminium-cobalt alloy, the resulting assembly needing virtually no machining and costing roughlyone-quarter as much as by the next most economic method. Even the centrifugal stage,which leads to the final discharge volute, is a precision casting which is practically a finishedpart when it leaves the mould. Any normal hydrocarbon fuel may beemployed with the 250, and it is injected from a Duplex nozzle mounted centrally in thelarge reverse-flow combustion chamber which projects from the end of the engine oppositeto the intake. The gases pass through the compressor turbine and free power' turbine,and are then turned downwards through 90 deg to exhaust from the underside of thepowerplant. The main output pinion is mounted at the front of a hollow shaft whichsurrounds the central shaft joining the com- pressor to its turbine. From the output piniona train of gears leads upwards to a row of accessory drives and to any of a variety ofpower take-offs which can be adapted to suit the requirements of the vehicle in which theengine is fitted. The variant illustrated is the turboprop version, in which a reduction gearreduces the speed of the output shaft to a maximum of 2,000 r.p.m. One of the good features of the 250 is thatits designers have deliberately limited the maximum shaft horsepower to 250. Theengine as it stands is potentially capable of higher powers, but this artificial restrictionenables the engine to deliver its full rated power up to 100 deg F ambient, or on standarddays up to altitudes of from 7,000 to 13,000ft, depending on forward speed. The restrictionis applied by an automatic hydromechanical control system, operating on the gas-gen:ratorsection of the engine and controlled by torque- meter pressure sensers and by four thermo-couples which limit turbine-inlet temperature to 1,228 deg K. Great efforts have been madeto render the engine well suited to maintenance by unskilled personnel in difficult conditions;the complete compressor can be removed by undoing three bolts and disconnecting an oilpipe; both the compressor and power turbines may be replaced without rebalancing, and thecombustion chamber can be removed merely by disconnecting the lines to the igniter andburn;r and then undoing a vee-clamp. Proto- type 250s are probably now running on thebench; production engines should be available within 18 months at a price which may benot more than $10,000 (£3,571). Reference: Sept. 19, 1958 (description andcutaway drawing). Model SOI Last December this unusual,but efficient and reliable, single-shaft engine became the first non-British turboprop to enterairline service. From the outset it has been tailored to the Lockheed Electra airliner, andit utilizes major portions very similar to those employed in the military T56 described later.The chief difference lies in the fact that in the military engine the reduction gear is mountedabove the drive-shaft, so that the engine intake is situated beneath the propeller spinner. The standard commercial engine is the5O1-D13, which is described and illustrated here. In all Electras except those for K.L.M.the engine is matched with an Aeroproducts four-blade propeller, incorporating B control.By biassing the engine governor and opening compressor bleed ports, special provision hasbeen made for reducing propeller r.p.m. to 970 to reduce noise on the ground In the airthe 501 is a constant-speed engine, operating at 13,820 r.p.m. Last September the D13 was cleared by theC.A.A. (now the F.A.A.) to an initial airline overhaul life of 1,000 hr. This figure, achievedthree months before scheduled services began, is particularly commendable, and arises largelyas a result of the extensive experience gained with the military T56. In our last engine issuewe briefly described the advanced 5O1-D15, with transonic flow through the first three com-pressor stages and shrouded first and second turbine stages. No further news is availableupon the progress of this engine. Model 550 Since our last engine reviewissue the 550, originally a private venture, has become a military project as the T61. Spon-sored by the U.S. Air Force, it is a two-spool engine, with a pressure ratio of at least 13 : 1and a design rating in excess of 5,000 e.h.p. It therefore must be regarded as a slightlysmaller competitor of the Rolls-Royce Tyne, and is initially foreseen as the powerplant ofthe winner of the U.S.A.F. competition for an advanced all-weather, high-altitude radarpicket aircraft. Bench tests have been in pro- gress for a considerable period, but the engineis not yet thought to have flown and is heavily classified by military security. T56 Standard powerplant of the LockheedC-130 military freighter, the single-shaft T56 has now logged more than 660,000 hr, the vastproportion of this being in military service with Tactical Air Command. The 50 hr flightclearance test of the YT56 was completed in September 1953; flight testing began with anengine mounted in a B-17 in March 1954 and intensive trials with engines fitted to a pairof YC-131C aircraft took place during the summer of that year. Production deliveries forthe C-130 began in January 1955 and some 1,500 engines have now been delivered. Nearlyall the engines currently in service are of the T56-A-1A model, rated like the Electra engineat 3,460 s.h.p. (3,750 e.h.p.) and matched to a three-blade 15ft propeller. The version cur-rently in production is the T56-A-7, rated at 3,755 s.h.p. (4,050 e.h.p.) and used in theLockheed C-130B with a four-blade propeller. Features include a Bendix fuel/air combus-tion starter and water injection for restoring power in tropical conditions. Still underdevelopment is the T56-A-10W, with a rating of 4,585 e.h.p. with water/alcohol injection. BELL Rocket Engine Department, BellAircraft Corp., Buffalo 5, N.Y. In our 1957 engine review issue a general appraisal of thework of the rocket engine department was given. Production of acid/aniline rocket motorsfor Nike Ajax missiles has now ceased, and the triple-barrel liquid-oxygen/kerosine enginefor the company's own GAM-63 Rascal air-to- surface missile is also practically out of pro-duction. The only new project is the Hustler rocket engine used in the second stages oforbital and space vehicles boosted by a Thor or Atlas. The Hustler has a single chamberpump-fed with fuming nitric acid and JP-4 fuel, and was originally developed for the pro-pulsion of a pod carried by the B-58 Hustler. BOEING Boeing Airplane Company,Seattle 24, Washington. For 15 years this immense company has been active in the fieldof small gas turbines, and the 502 series of engines has established a high reputation forreliability and trouble-free service in marine, industrial, vehicular and aircraft applications.Bench-testing of the first engine began in 1947, the output being 100 h.p. and the specificconsumption 1.8; the current production engine is the 502-10C, rated at 240 s.h.p. with a speci-fic consumption of unity. Some 700 similar engines have been delivered. Aircraft applica-tions include shaft-drive and tip-drive helicop- ters and the RP-77D target drone developedfor the U.S. Army by Radiop!ane. The latter is powered by the 502-10F turboprop, ratedat 300 h.p. at 3,400 r.p.m. with a specific con- sumption of 0.95 and a dry weight of 300 Ib.These drones can exceed 400 m.p.h. and one recently reached 46,500ft. Late last year aCessna L-19 powered by a 502-10F flew non- stop from Seattle to Ft. Rucker, Alabama,cruising at 20,000 to 27,000ft. T60 Boeing's industrial products divisionhave for about a year been busily engaged in the development of an entirely new power-plant. Known as the Boeing Model 520-2, the engine is under development for the NavyBureau of Aeronautics and carries the Service designation of T60. The manufacturer's owndescription states that the engine "features aerodynamic refinement of single-stage com-pression and expansion. . . . Other features to simplify installation, operation and main-tenance include eductors for ventilation cool- ing, automatic starting and control, accessibilityfor inspection and replacement, and field- interchange of rotor components withoutdynamic and static balance of the assembly. Main rotor bearings are floating sleeve andslipper types." The illustration and specifica- tion are appropriate to the -2 unit, which hasbeen on test since March 1958 and reached the specification ratings of 400 s.h.p. and0.72 specific consumption at the beginning of
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