General Electric TF39

TF39
	A TF39 on a C-5 Galaxy at ILA (Internationale LuftfahrtAusstellung) in Berlin, 2008
Type	High-bypass turbofan
National origin	United States
Manufacturer	GE Aviation
First run	1964
Major applications	Lockheed C-5 Galaxy
Number built	463
Developed into	General Electric CF6 ; General Electric LM2500

The General Electric TF39 was a high-bypass turbofan engine that was developed to power the Lockheed C-5 Galaxy. The TF39 was the first high-power, high-bypass jet engine developed. The TF39 was further developed into the CF6 series of engines, and formed the basis of the LM2500 marine and industrial gas turbine. On September 7, 2017, the last active C-5A powered with TF39 engines made its final flight to Davis-Monthan Air Force Base for retirement.^[1] The TF39 was effectively retired, and all remaining active C-5 Galaxys are now powered by F138 (General Electric CF6-80C2) engines.

Development[]

The United States Air Force opened the "CX-X Program" in 1964, intending to produce a next-generation strategic airlifter. Of the several airframe and engine proposals returned for consideration, Lockheed's aircraft and General Electric's engine were selected for the new design in 1965.

The high-bypass turbofan was a huge leap in engine performance, offering a thrust of 43,000 pounds, while improving fuel efficiency by about 25%.^[2] The TF39 had an 8-to-1 bypass ratio, a 25-to-1 compressor pressure ratio, and a 2,500 °F (1,370 °C) turbine temperature made possible by advanced forced-air cooling. The first engine went for testing in 1965. Between 1968 and 1971, 463 TF39-1 and -1A engines were produced and delivered to power the C-5A fleet.

Design[]

TF39s on a C-5 Galaxy, from the rear

The TF39 was a revolutionary 1960s engine rated from 41,000 to 43,000 lb_f (191 to 205 kN) of thrust. It introduced use of a large by-pass ratio which, together with advances in core technology, contributed to a significant improvement in fuel efficiency over engines available at the time.

The engine included features developed from previous GE engines:

Variable vanes (used in the J79/CJ805^[3])
Turbine cooling techniques (advanced from the J93 used in the XB-70^[3])
Cascade-type thrust reverser (from the CJ805^[3])
Snubbered first stage fan blades (snubbers, or mid-span shrouds, had been introduced by GE on the YJ93 first stage compressor blades^[4])

Today, a conventional turbofan featuring a T-staged fan would have an overhung fan rotor (without any inlet guide vanes), followed by one or more T-stages supercharging the core stream alone.^[5] The name T-staged fan is derived from the overall appearance of the LP compressor when the side elevation is shown diagrammatically.

GE took a different approach with their first high bypass ratio turbofan, the TF39. It is a unique, very complex design.^[6] The T-stage, which supercharges the core stream, is located ahead of the main fan rotor. The T-stage itself comprises an overhung mini-rotor followed by a set of outlet guide vanes; the main fan rotor is located immediately behind these OGVs. Outboard of the T-stage rotor are the main inlet guide vanes, which only affect the bypass stream. The T-stage rotor extends to about half the main rotor stage annulus^[4]^[7] and runs in a tip shroud. The main fan stage has a mid-span platform/flow splitter which separates the single-stage outer annulus from the two-stage inner annulus.^[7] These two stages mainly supercharge the 16-stage high-pressure compressor.^[8] However, a fair proportion of the air entering the T-stage is bled off into the bypass duct, there being two annular passages leading to the bypass duct. The nominal bypass ratio of 8:1 refers to the ratio of total bypass mass flow to HP compressor entry mass flow.

The rotor blades are snubbered. 'Snubbers' are protuberances that stick out at right angles to the fan aerofoil at mid^[4] to 2/3 span.^[9] At speed, the snubbers on adjacent fan blades butt-up against each other to prevent blade failures due to flutter.^[9] They, together with the second-stage inlet guide vanes in the outer half of the duct, are visible when looking into the engine intake.^[10]^[11]

The high-bypass ratio of 8:1 for the TF-39 had its origins in the lift-fan technology demonstrated by GE in the XV-5 Vertifan aircraft.^[3] This aircraft had two X353-5 engines, each consisting of a 62.5-inch-diameter^[12] lift-fan driven by a gas generator (J85). The bpr in VTOL operation was 12.3.^[13] This tip-turbine driven lift-fan concept was turned 90 degrees and developed as an 80-inch-diameter "cruise fan" demonstrator, driven by a J79 gas generator.^[3] For the CX-X program GE demonstrated a half-scale engine, the GE1/6, with 15,830 lb thrust and an sfc of 0.336.^[14] This was developed into the TF39 with a 97 in diameter fan.^[7]

Applications[]

Lockheed C-5A/B/C Galaxy

Specifications (TF39-1C)[]

A Boeing B-52E (Serial Number 57-0119) testing a TF39 on the right inboard engine pod. The TF39 has more than double the thrust of the twin Pratt & Whitney J57s that were originally in that spot.

Data from ^[15]

General characteristics

Type: Turbofan
Length: 312 in (792 cm)
Diameter: 97 in (246 cm)
Dry weight: 8000 lb (3630 kg)

Components

Compressor: Axial, 2-stage fan, 16-stage high-pressure compressor
Combustors: Annular
Turbine: Axial, 2-stage high-pressure turbine, 6-stage low-pressure turbine

Performance

Maximum thrust: 43,300 lbf (193 kN)
Overall pressure ratio: 25:1
Fuel consumption: ~3.7646 lb/s (1.7075 kg/s)
Specific fuel consumption: 0.313 lb/(lbf⋅h) (8.9 g/(kN⋅s))
Thrust-to-weight ratio: 5.4

References[]

^ http://www.westover.afrc.af.mil/News/Article-Display/Article/1303782/and-then-there-were-none-the-final-c-5a-departs-westover-arb-for-retirement/
^ General Electric - CF6 history Archived 2009-01-27 at the Wayback Machine
^ Jump up to: ^a ^b ^c ^d ^e "seven decades of progress" General Electric, ISBN 0-8168-8355-6, Aero Publishers Inc. p.152
^ Jump up to: ^a ^b ^c "Gas Turbine Technology Evolution: A Designer's Perspective" Bernard L. Koff, Journal of Propulsion and Power, Vol.20 No. 4, July–August 2004, p.591
^ https://www.google.co.uk/search?q=br715&espv=2&biw=1401&bih=805&source=lnms&tbm=isch&sa=X&ved=0ahUKEwidx4-E-u3LAhXBPhQKHZKiC3cQ_AUIBygC#tbm=isch&q=GE90&imgrc=QRZtDVSTsB7JlM%3A
^ http://www.airliners.net/aviation-forums/tech_ops/read.main/86450
^ Jump up to: ^a ^b ^c "Flight Manual USAF Series C5A and C5B Airplanes", TO 1C-5A-1, Lockheed Martin Corporation
^ "Aviation Week" 16 August 1965, shown as Figure 35 in "The History Of The Rolls-Royce RB211 Turbofan Engine", ISBN 978-1-872922-48-5, The Rolls-Royce Heritage Trust
^ Jump up to: ^a ^b "Flutter and Resonant Vibration Characteristics of Engine Blades" A.V. Srinivasan, 97-GT-533, ASME, p.8
^ TF39 front view. planes.cz
^ TF39 running. airliners.net
^ "Aerodynamic characteristics of a Large-Scale Model with a High Disk Loading Lift Fan Mounted in the Fuselage" Aoyagi, Hickey and deSavigny, NASA TN D-775
^ "Jet Propulsion for Aerospace Applications" Second Edition, Hesse and Mumford, Pitman Publishing Corporation, 1964, Table 11.1
^ "The Development of Jet and Turbine Engines", 4th edition, Bill Gunston, ISBN 0 7509 4477 3, p. 192
^ Gas Turbine Engines. Aviation Week & Space Technology Source Book 2009. p. 119

Gunston, Bill (2006). World Encyclopedia of Aero Engines, 5th Edition. Phoenix Mill, Gloucestershire, England, UK: Sutton Publishing Limited. ISBN 0-7509-4479-X.

External links[]

General Electric TF39 website

[1] ttp://www.westover.afrc.af.mil/News/Article-Display/Article/1303782/and-then-there-were-none-the-final-c-5a-departs-westover-arb-for-retirement/

[2] General Electric - CF6 history Archived 2009-01-27 at the Wayback Machine

[ge-3] Jump up to: ^a ^b ^c ^d ^e "seven decades of progress" General Electric, ISBN 0-8168-8355-6, Aero Publishers Inc. p.152

[koff-4] Jump up to: ^a ^b ^c "Gas Turbine Technology Evolution: A Designer's Perspective" Bernard L. Koff, Journal of Propulsion and Power, Vol.20 No. 4, July–August 2004, p.591

[5] ttps://www.google.co.uk/search?q=br715&espv=2&biw=1401&bih=805&source=lnms&tbm=isch&sa=X&ved=0ahUKEwidx4-E-u3LAhXBPhQKHZKiC3cQ_AUIBygC#tbm=isch&q=GE90&imgrc=QRZtDVSTsB7JlM%3A

[6] ttp://www.airliners.net/aviation-forums/tech_ops/read.main/86450

[manual-7] Jump up to: ^a ^b ^c "Flight Manual USAF Series C5A and C5B Airplanes", TO 1C-5A-1, Lockheed Martin Corporation

[8] "Aviation Week" 16 August 1965, shown as Figure 35 in "The History Of The Rolls-Royce RB211 Turbofan Engine", ISBN 978-1-872922-48-5, The Rolls-Royce Heritage Trust

[srinivasan-9] Jump up to: ^a ^b "Flutter and Resonant Vibration Characteristics of Engine Blades" A.V. Srinivasan, 97-GT-533, ASME, p.8

[10] TF39 front view. planes.cz

[11] TF39 running. airliners.net

[12] "Aerodynamic characteristics of a Large-Scale Model with a High Disk Loading Lift Fan Mounted in the Fuselage" Aoyagi, Hickey and deSavigny, NASA TN D-775

[13] "Jet Propulsion for Aerospace Applications" Second Edition, Hesse and Mumford, Pitman Publishing Corporation, 1964, Table 11.1

[14] "The Development of Jet and Turbine Engines", 4th edition, Bill Gunston, ISBN 0 7509 4477 3, p. 192

[15] Gas Turbine Engines. Aviation Week & Space Technology Source Book 2009. p. 119

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[15]

show v t General Electric aircraft engines
Turbojets	CJ610 CJ805 GE4/J5P J31 J33 J35 J47 J73 J79 J85 J87 YJ93 J97 YJ101
Turbofans	Affinity CF6 CF34 CF700 CFE738† CFM56† CJ805-23 F101 F108† F110 F118 YF120 F136† F404/F412 F414 GE90 GE9X GEnx GP7000† HF120† LEAP† Passport RM12† TF34 TF39 XA100
Turboprops/Turboshafts	Catalyst CT7 CT58 CT64 GE27 GE36 GE38 H-Series T31 T58 T64 T407 T408 T700 T901
Aeroderivative gas turbine engines	LM500 LM1500 LM1600 LM2500 LM6000 LM9000 LMS100
† Joint development aeroengines

show v t United States military gas turbine aircraft engine designation system
Turbojets	J30 J31 J32 J33 J34 J35 J36 J37 XJ38 J39 J40 XJ41 J42 J43 J44 J45 J46 J47 J48 XJ49 J52 J54 J55 J57 J58 J60 J65 J67 J69 J71 J73 J75 J79 J81 J83 J85 J87 YJ93 J97 J100 YJ101 J102 J400 J402 J403 J700
Turboprops/ Turboshafts	T31 T33 T34 T35 T36 T37 T38 T39 T40 T41 T44 T46 T47 T49 T50 T51 T53 T54 T55 T56 (variants) T57 T58 T60 T61 T62 T63 T64 T65 T66 T67 T72 T73 T74 T76 T101 T400 T406 T407 T408 T700 T701 T702 T703 T706 LHTEC T800 APW T800 T900 T901
Turbofans	TF30 TF33 TF34 TF35 TF37 TF39 TF41 F100 F101 F102 F103 F104 F105 F106 F107 F108 F109 F110 F112 F113 F117 F118 F119 YF120 F121 F122 F124 F125 F126 F127 F128 F129 F130 F135 F136 F137 F138 F401 F402 F404 F405 F408 F412 F414
Adaptive cycle engines	XA100 XA101

show v t United States Air Force system numbers
100–199	100 101 P 102 103 104 105 106¹ 107 A-1 A-2 108¹ 109¹ 110 111¹ 112 113¹ 114¹ 115¹ 116¹ 117 M 118 A 119 C/F E T Y 120 121 122 123 124 125 127¹ 129 131 132 133 134¹ 136¹ 137¹ 138 139 140 141¹ 142 143–197¹ 199 B C D
200–299	200 201 A/L B/W E 202 203¹ 204 205 206 207¹ 208 209¹ 210 211¹ 213 214 215¹ 216 217 218 219¹ 220 221 222 A 223¹ 224 225¹ 226 227–238¹ 239 240–278¹ 279 280–298¹
300–399	300 301¹ 302 303 304¹ 305¹ 306 A/L B 307 308 309 310¹ 311¹ 312¹ 313¹ 314 315 A-1 A-2 316 318¹ 319 320¹ 321 322¹ 324 L M/N 326 327 E 328 E 329 F 330¹ 331¹ 332¹ 333¹ 334¹ 335 336 337 338–379¹ 380 A/B/E/F/N P 381–397¹ 399
400–499	400 B/C/N E G/H M 401 402 403¹ 405 406¹ 408¹ 409¹ 410 E 411 E L 413 414 416 L M (I) 418 419¹ 420 L/W 421¹ 422 423 424 425 426 L 427 L 428 L 429 431 434 435 L 436 441 A L 442 443 444¹ 445 446 447 448¹ 449¹ 450 451 L 452 453 454¹ 457¹ 460 L 462 463 464 465 468 471 L (I) L (II) 474 L N 475¹ 476 E 477 478 A 479¹ 481 L 482 E M/Z 484 485 Z 487 488 490 491¹ 493 494 495 496 497 L 498 C E L 499
500–599	501–519¹ 521–529¹ 531–541¹ 543–549¹ 550 551–559¹ 560 561–569¹ 571–579¹ 580 581–589¹ 591 593–599¹
600–699	601 A 602 A 603 A 605 606 607 608¹ 609 610¹ 611¹ 612¹ 613¹ 615¹ 616 617¹ 619¹ 620 621 A/B (I) 622 624 626¹ 628¹ 629¹ 630¹ 631¹ 634 A B 636¹ 637¹ 638 641 644¹ 645¹ 646¹ 647¹ 648 A P 649 P 653¹ 654¹ 655 656 657¹ 658¹ 659¹ 662¹ 663¹ 665 666 669¹ 671¹ 672 673¹ 676¹ 677¹ 678¹ 681 682¹ 683 A V 684¹ 687 P 688¹ 689¹ 691 C Z 692¹ 693 694¹ 695 A B C L N P Q R S (I) S (II) 696¹ 697¹ 698¹ 699¹
700–799	700–735¹ 737¹ 738¹ 739¹ 740¹ 742 743 744¹ 745 746–753¹ 755–799¹
800–899	800¹ 801¹ 802 803¹ 804¹ 805¹ 807 808–816¹ 818¹ 819¹ 820¹ 821¹ 822¹ 824–831¹ 832 833¹ 834 835–845¹ 847–899¹
900–999	900–951¹ 952 853¹ 854¹ 855¹ 956 957–967¹
¹ Unknown or not assigned