Pratt & Whitney J75

J75 / JT4A
	Two JT4As installed on a KLM DC-8
Type	Turbojet
National origin	United States
Manufacturer	Pratt & Whitney
First run	1955
Major applications	Boeing 707 ; Convair F-106 Delta Dart ; Douglas DC-8 ; Lockheed U-2 ; Republic F-105 Thunderchief
Developed from	Pratt & Whitney J57
Developed into	Pratt & Whitney GG4/FT4

The Pratt & Whitney J75 (civilian designation: JT4A) is an axial-flow turbojet engine first flown in 1955. A two-spool design in the 17,000 lbf (76 kN) thrust class, the J75 was essentially the bigger brother of the Pratt & Whitney J57 (JT3C). It was known in civilian service as the JT4A, and in a variety of stationary roles as the GG4 and FT4.

Design and development

In military use, the J75 was used on the Convair F-106 Delta Dart, Lockheed U-2, and Republic F-105 Thunderchief. It was also utilized in the prototype and experimental Avro Canada CF-105 Arrow, Lockheed A-12, Martin P6M SeaMaster, North American YF-107, and Vought XF8U-3 Crusader III.

Before the arrival of the Pratt & Whitney JT3D turbofan engine, the JT4A was used to power certain Boeing 707 and Douglas DC-8 models, bringing improved field performance in the medium-range Boeing 707-220 and Douglas DC-8-20, and intercontinental range in the Boeing 707-320 and the Douglas DC-8-30. By late 1959, P&W had considered introducing a turbofan version of the J75, which was to have tentatively been named the TF75 or JT4D.^[1] Apparently, little interest was shown by the aircraft industry, so the variant was dropped.^{[citation needed]}

Marine & power generation

After its relatively short lifetime in the aircraft role, the JT4A found more enduring use in the naval role, where the FT4 was produced in a variety of models between 18,000 and 22,000 hp (13 and 16 MW). Well-known uses include the first all-turbine warships, the Canadian Iroquois-class destroyers, as well as the United States Coast Guard's Hamilton-class cutters, the 1970s-built icebreakers Polar Sea and Polar Star (each 3 engines in CODOG configuration), and it was considered for the US Navy's Asheville-class gunboat. The same basic powerplant saw much wider use as a peak demand power turbine running on natural gas. From its introduction in 1960 over 1,000 FT4s have been sold, with many of them still in operation for electrical generation. Outdated by modern standards, refits are available that add catalytic converters to lower their emissions.

Variants

J75-P-1
J75-P-3: 16,470 lbf (73.26 kN) thrust
J75-P-5: 17,200 lbf (76.51 kN) thrust
J75-P-9
J75-P-11
J75-P-13B: 17,000 lbf (75.62 kN) thrust
J75-P-15W: 24,500 lbf (108.98 kN) afterburning thrust
J75-P-17: 24,500 lbf (108.98 kN) afterburning thrust^[2]
J75-P-19: 24,500 lbf (108.98 kN) afterburning thrust^[2]
J75-P-19W: 26,500 lbf (117.88 kN) afterburning thrust with water injection^[2]
JT4A-3: 15,800 lbf (70.28 kN)^[2]
JT4A-4: 15,800 lbf (70.28 kN)
JT4A-9: 16,800 lbf (74.73 kN)^[2]
JT4A-11: 17,500 lbf (77.84 kN) thrust^[2]
JT4A-29: (J75-P-19W) 26,500 lbf (117.88 kN) afterburning thrust with water injection^[2]

Applications

J75

JT4A

Boeing 707 (specifically, the 707-220 and 707-320)
Douglas DC-8 (specifically, the DC-8-20 and DC-8-30)

Specifications (JT4A-11)

Data from Jane's All the World's Aircraft 1962-63,^[2] Aircraft engines of the World 1966/67,^[3] Flight:Aero Engines 1960^[4]

General characteristics

Type: turbojet
Length: 144.1 in (3,660 mm)
Diameter: 43 in (1,092 mm)
Dry weight: 5,100 lb (2,313.3 kg)

Components

Compressor: 2-spool axial compressor
- LP compressor: 8-stage axial (4 stages titanium, 4 stages steel)
- HP compressor: 7-stage axial compressor
Combustors: cannular with 8 burner cans in an annular combustion chamber
Turbine: 2-spool axial turbine
- HP turbine: 1-stage axial
- LP turbine: 2-stage axial
Fuel type: Jet A-1 / ASTM A-1 / MIL-J-5624 / JP-1 / JP-4
Oil system: return pressure spray system at 45 psi (310 kPa)

Performance

Maximum thrust: 17,500 lbf (77.84 kN) at 6,720 rpm LP for take-off
Overall pressure ratio: 12.5:1
Air mass flow: 256 lb/s (7,000 kg/min) at 8,975 rpm HP
Specific fuel consumption: 0.74 lb/(lbf⋅h) or 21 g/(kN⋅s) at maximum continuous rpm
Thrust-to-weight ratio: 3.147

Notes

^ "page 458". Flight. October 30, 1959.
^ ^a ^b ^c ^d ^e ^f ^g ^h Taylor, John W.R. FRHistS. ARAeS (1962). Jane's All the World's Aircraft 1962-63. London: Sampson, Low, Marston & Co Ltd.
^ Wilkinson, Paul H. (1966). Aircraft engines of the World 1966/67 (21st ed.). London: Sir Isaac Pitman & Sons Ltd.
^ "Aero Engines 1960". Flight International: 367–387. 18 March 1960. Retrieved 1 January 2018.

References

Taylor, John W.R. FRHistS. ARAeS (1962). Jane's All the World's Aircraft 1962-63. London: Sampson, Low, Marston & Co Ltd.

External links

Pratt & Whitney J75/JT4 webpage

[1] "page 458". Flight. October 30, 1959.

[JAWA62-63-2] ^ ^a ^b ^c ^d ^e ^f ^g ^h Taylor, John W.R. FRHistS. ARAeS (1962). Jane's All the World's Aircraft 1962-63. London: Sampson, Low, Marston & Co Ltd.

[AEotW6667-3] Wilkinson, Paul H. (1966). Aircraft engines of the World 1966/67 (21st ed.). London: Sir Isaac Pitman & Sons Ltd.

[Flight180360p367-4] "Aero Engines 1960". Flight International: 367–387. 18 March 1960. Retrieved 1 January 2018.

[1]

[2]

[3]

[4]

v t e Pratt & Whitney aircraft engines
Radial engines	R-985 R-1340 R-1535 R-1690 R-1830 R-1860 R-2000 R-2060 R-2180-A R-2180-E R-2270 R-2800 R-4360 Double Wasp Hornet (A) Hornet B Twin Hornet Twin Wasp (R-1830) Twin Wasp (R-2000) Twin Wasp E Twin Wasp Junior Wasp series Wasp Wasp Junior Wasp Major Yellow Jacket
H piston engines	X-1800/XH-2600 XH-3130 (XH-3730)
Free-piston gas turbines	PT1
Turbojets	JT3C JT4A JT6 JT7 JT8A JT9 JT11 JT12 J42 J48 J52 J57 J58 J60 J75 J91
Turbofans	GP7000† JT3D JT4D JT8D JT9D JTF10 JTF10A JT10D JTF14 JTF16 JTF17 JTF22 PW1000G PW1120 PW2000 PW4000 PW5000 PW6000 RTF-180† STF200 SuperFan† V2500† F100 F105 F117 F119 F135 F401 RM8† TF30 TF33 XA101 XA103
Turboprops/Turboshafts	APW34† JFTD12 PT2 PT3 PT4 PT5 T34 XT45 T52 XT57 T73 T800-APW† T900†
Propfans	578-DX†
Rocket engines	RL10 XLR-129
Aeroderivative gas turbine engines	GG3/FT3 GG4/FT4 FT8
Subsidiaries	Pratt & Whitney Canada Pratt & Whitney Rocketdyne
Key people	Leonard S. Hobbs George J. Mead Wright Parkins Perry Pratt Frederick Rentschler Richard "Dick" Soderberg Andrew Willgoos
† Joint development aeroengines See also: Pratt & Whitney Canada aeroengines

v t e 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 J51 J52 J53 J54 J55 J56 J57 J58 J59 J60 J61 J63 J65 J67 J69 J71 J73 J75 J79 J81 J83 J85 J87 J89 J91 YJ93 J95 J97 J99 J100 YJ101 J102 J400 J401 J402 J403 J700
Turboprops/ Turboshafts	T30 T31 T33 T34 T35 T36 T37 T38 T39 T40 T41 T42 T43 T44 T45 T46 T47 T48 T49 T50 T51 T52 T53 T54 T55 T56 (variants) T57 T58 T60 T61 T62 T63 T64 T65 T66 T67 T68 T69 T70 T71 T72 T73 T74 T76 T78 T80 T100 T101 T400 T405 T406 T407 T408 T700 T701 T702 T703 T706 T708 LHTEC T800 APW T800 T900 T901
Turbofans	TF30 TF31 TF32 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 F400 F401 F402 F404 F405 F408 F412 F414 F415
Adaptive cycle engines	XA100 XA101 XA102 XA103

v t e 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 L M 118 A L P 119 C/F E L T Y 120 121 122 123 124 125 126 127¹ 128 129 130 131 132 A B 133 134¹ 135 136¹ 137¹ 138 139 140 141¹ 142 143–197¹ 198 199 B C D Y
200–299	200 201 A/L B/W E 202 203¹ 204 205 206 207¹ 208 209¹ 210 211¹ 212 213 214 215¹ 216 217 218 219¹ 220 221 222 A G 223¹ 224 225¹ 226 227–238¹ 239 240–278¹ 279 280–298¹ 299
300–399	300 301¹ 302 303 304¹ 305¹ 306 A/L B 307 308 309 310¹ 311¹ 312¹ 313¹ 314 315 A-1 A-2 316 317 318¹ 319 320¹ 321 322¹ 323 324 L M/N 325 326 327 E 328 E 329 F 330¹ 331¹ 332¹ 333¹ 334¹ 335 336 337 338–379¹ 380 A/B/E/F/N P 381–397¹ 398 399 A B
400–499	400 B/C/N E G/H M 401 402 403¹ 404 405 B C D 406¹ 407 408¹ 409¹ 410 E L 411 E L 412 413 414 L M 415 416 L M (I) M (II) P Q 417 418 L M 419¹ 420 L/W 421¹ 422 423 424 425 426 L M 427 L M 428 A L 429 430 431 G (I) G (II) 432 433 434 435 A L 436 437 438 439 440 441 A D L 442 443 444¹ 445 L M 446 447 448¹ 449¹ 450 451 D L 452 453 454¹ 455 456 457¹ 458 459 460 L 461 462 463 464 465 466 467 468 469 470 471 L (I) L (II) 472 473 474 L N 475¹ 476 E 477 478 A T 479¹ 480 481 L 482 E L M/Z 483 484 L M N 485 L Z 486 487 488 489 490 L M 491¹ 492 493 494 495 L (I) L (II) 496 497 A L (I) L 498 A C D E L 499 A C D
500–599	500 501–519¹ 520 521–529¹ 530 531–541¹ 542 543–549¹ 550 A E 551–559¹ 560 A F 561–569¹ 570 571–579¹ 580 A E 581–589¹ 590 591 592 593–599¹
600–699	600 601 A L 602 A L 603 A L 604 605 606 607 608¹ 609 610¹ 611¹ 612¹ 613¹ 614 615¹ 616 617¹ 618 619¹ 620 621 A/B (I) B (II) 622 623 624 625 626¹ 627 628¹ 629¹ 630¹ 631¹ 632 633 634 A B 635 636¹ 637¹ 638 639 640 641 642 643 644¹ 645¹ 646¹ 647¹ 648 A D P 649 A B C D E F L P 650 651 652 653¹ 654¹ 655 A (I) A (II) P 656 657¹ 658¹ 659¹ 660 661 662¹ 663¹ 664 665 A (I) A (II) 666 A C/P 667 668 669¹ 670 671¹ 672 A M/P 673¹ 674 675 676¹ 677¹ 678¹ 679 680 681 D E 682¹ 683 A J V 684¹ 685 686 687 J P 688¹ 689¹ 690 691 C X 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 736 737¹ 738¹ 739¹ 740¹ 741 742 743 744¹ 745 746–753¹ 754 755–799¹
800–899	800¹ 801¹ 802 L (I) L (II) 803¹ 804¹ 805¹ 806 807 808–816¹ 817 818¹ 819¹ 820¹ 821¹ 822¹ 823 824–831¹ 832 833¹ 834 835–845¹ 846 847–899¹
900–999	900–951¹ 952 853¹ 854¹ 855¹ 956 957–967¹ 968
¹ Unknown or not assigned