Designations Of U.S. Military Aero Engines

Copyright © 2000-2024 Andreas Parsch

1 Introduction

2 Piston Engines

3 Jet and Turbine Engines, 1946 - 1968

4 Rocket Engines

5 The Current System (MIL-STD-1812A)

6 Sources

1 Introduction

For the engines of its first aircraft, the US military services used the manufacturers' names. Soon after World War I, however, more formal designation systems were devised not only for the aircraft themselves but also for their engines. When jet, turbine and rocket engine development started at the end of World War II, formal designations were assigned to these types of engines almost from the beginning. In the last decades, however, there is a trend towards using manufacturers' designations again for engines which were not developed specifically for the military.

The following graph shows the various documents and standards used to define the aero engine designation systems. A bold black arrow indicates, that the system underwent no or only minor changes, when defined in a new document. A light gray arrow indicates a major change, i.e. the designation system was superseded by a completely different one.

Engine Designation Systems Lineage

This article explains the various engine designation systems and lists all aircraft and missile engines, which received a military designation, and the aircraft or missiles which used them. Because the focus of the article is on the designations, I don't try to give specific details for the engines (like power rating, etc.). These details can differ significantly between models of the same basic engine anyway.
For each engine type, I try to provide a complete list of US military aircraft, which used this engine. To keep these lists reasonably short, I use the following terse format for an aircraft type:

Usually only the basic designation (without specific model letters or numbers) is given. That means, that all - or almost all - models of this type used the engine. Exceptions are listed as users of the approriate alternate engine. If an entry is in brackets, the type was planned to use the engine, but not a single example was completed before the aircraft and/or engine was cancelled. Additionally, each list of aircraft designations is headed by a descriptor of the designation system used.

2 Piston Engines

Since the early 1920's, piston engines are designated by a system based on cylinder arrangement and total piston displacement. This designation system was later formally defined in Air Force/Navy Aeronautical (ANA) Bulletin 395, which was replaced by MIL-STD-1557 on 28 January 1974. The latter document was superseded by the current MIL-STD-1812 on 28 February 1991.

Examples: V - 1650 - 7
R - 4360 - 35 C
X O - 470 - 5
(5) (1) (2) (3) (4)

The letter (1) indicates the cylinder arrangement of the engine:

Optionally, the letter could be prefixed by one of the modification letters:

MIL-STD-1557 dropped all letters and prefixes, except O, R and V, and added the designator

The number (2) is the total piston displacement of the engine, rounded to the next 5 cubic inches.

(3) is the model number for a particular version of the engine. The Army and Air Force used odd numbers from 1 up, while the Navy used even numbers from 2 up. In MIL-STD-1557, this was revised. The Air Force was assigned model numbers 100 to 399, the Navy 400 to 699 and the Army 700 to 999. This was done to match the procedure for jet/turbine model numbers defined by MIL-STD-879.

(4) is an optional letter for designating minor modifications of an engine model. Letters are assigned alphabetically from A on (I and O are not used). The letter W is reserved for engines with water injection. In MIL-STD-1557, the letter T was reserved for training (i.e. non-flying) engines. T could be combined with other letters, e.g. the training version of the R-1830-92A engine would be designated R-1830-92AT.

(5) is an optional status prefix:

This designation system could lead to the same basic (arrangement - displacement) designation for two different engines. E.g., the Liberty 12 engine of the 1920s and the Merlin engine of WW II were both officially known as V-1650. However, I don't know any case, where this occured for contemporary engines, so this did not pose problems in "real life".
(It is also possible, that the displacement was sometimes rounded to the next 10 cubic inches to get different designations for engines with similar displacement.)

Note: While this system was theoretically revised by MIL-STD-1812, it is - to all intents and purposes - still in use today, mainly because of two reasons:

Designation List:

Designation Manufacturer and Model Remarks; Aircraft
H-2470 Lycoming XH-2470-1 Army/AF(1924-1962): (1)P-54
Navy(1922-1962): (1)F14C-1
H-2600 Pratt & Whitney X-1800-SA2G  
H-3730 Pratt & Whitney  
H-4070 Menasco XH-4070-1  

IV-1430 Continental XI-1430-1 Army/AF(1924-1962): (2)P-49, [(1)P-52], [(1)P-53], (2)P-67
IV-2040 Menasco XIV-2040-1  
IV-2220 Chrysler XIV-2220-1  

L-330 Martin  
L-365 Menasco Pirate C-4 Army/AF(1924-1962): (1)PT-20
Navy(1922-1962): (1)JH
L-375 DeHavilland Gipsy Major Army/AF(1924-1962): (1)PT-24
L-390 Ranger 6-390-B  
L-410 Ranger 6-410-B2  
L-440 Ranger 6-440-C2 Army/AF(1924-1962): (1)UC-61K, (1)XUC-86A, (2)OA-14, (2)PG-2, (1)PT-19, (1)PT-26
Navy(1922-1962): (2)J4F, (1)J2K, (1)NR
L-510 Miller Double 4-255 Army/AF(1924-1962): [(1)P-57]
L-825 Liberty 6 Army(1919-1924): (1)PN-1

O-15 Righter Army/AF(1924-1962): (1)OQ-2, (1)OQ-3, (1)OQ-7, (1)OQ-13
Navy(1922-1962): (1)TDD
O-40 Muncie Gear  
O-45 Righter/Kiekhaefer Army(1924-1962): (1)OQ-6, (1)OQ-14, (1)OQ-15, (1)OQ-16, (1)OQ-17
Navy(1922-1962): (1)KD3G, (1)KD4G, (1)KDR, (1)TDD-3/4
O-90 McCulloch Army(1924-1962): (1)OQ-6A, (1)OQ-19
Navy(1922-1962): (1)KD2R
O-100 McCulloch Navy(1922-1962): (1)KD6G, (1)KD2R-3/5
Missiles: (1)MQM-33, (1)MQM-36
O-145 Lycoming O-145-B2 Army/AF(1924-1962): (1)UC-90A, (1)C-92, (1)C-95, (1)L-2D/F/J, (1)L-3G/H, (1)L-4C/G
O-150 Franklin 4-AC-150 Army/AF(1924-1962): (1)L-2E/G/K/L
O-170 Continental A-65 Army/AF(1924-1962): (1)C-83, (1)UC-90, (1)L-2, (1)L-3, (1)L-4, (1)L-8, (1)O-54, (1)O-55, (1)O-57(L-2), (1)O-58(L-3), (1)O-59(L-4)
Navy(1922-1962): (1)NE
O-175 Franklin 4-AC-176-B2 Army/AF(1924-1962): (1)L-3D, (1)L-4D
O-180 Franklin 4-AC-176-F3  
O-190 Continental C-85 Army/AF(1924-1962): (1)L-16
O-200 Franklin 4-AC-199-E4 Army/AF(1924-1962): (1)C-65, (1)L-6, (1)L-7, (1)L-9, (1)O-63(L-6), (1)PQ-8
Navy(1922-1962): (1)XTDC-1
O-200 Continental (Teledyne) O-200-A Joint(1962+): (1)X-26B
O-205 Continental Army/AF(1924-1962): (1)L-16B, (1)L-18
O-235 Lycoming O-235-A Navy(1922-1962): (1)AE, (1)HE(AE)
O-235 Lycoming (Textron) O-235-L2C Joint(1962+): (1)TG-7, (1)RG-8
O-290 Lycoming O-290-B Army/AF(1924-1962): (1)C-107, (1)H-24, (1)L-14, (1)L-15, (1)L-21(U-7), (1)PQ-8A, (1)R-9
Navy(1922-1962): (1)TDC
Joint(1962+): (1)U-7
O-300 Franklin 6-AC-298-F3 Army/AF(1924-1962): [(1)PQ-9], [(2)PQ-10], (1)PQ-13, (1)PQ-14
Navy(1922-1962): (1)TD2C
O-335 Aircooled Motors (Franklin) Army/AF(1924-1962): (1)H-13, (1)H-23, (1)H-30, (1)T-35
Navy(1922-1962): (1)HTE, (1)HTL-1/3/5, (1)HUM
O-360 Lycoming Joint(1962+): (1)H-55
O-360 Continental Joint(1962+): (2)O-2, (1)O-3, (1)T-41, (1)XV-8A
O-405 Franklin 6-ACV-405 Army/AF(1924-1962): (2)BQ-1, (1)XUC-86B, (1)PQ-15, (1)R-6, [(1)R-7], (1)R-8
Navy(1922-1962): (1)HOS, (1)TD3C
O-425 Franklin 6-AC-425 Army/AF(1924-1962): (1)H-18, (1)L-13, [(1)OA-15]
O-435 Lycoming O-435-A Army/AF(1924-1962): (2)XBQ-2, (2)BQ-4, (1)H-13H/J/L/M/N/P/Q/S/T, (1)H-22, (1)L-5, (1)L-22(L-17D), (2)L-23(U-8), (1)L-24, (1)L-26(U-9), (1)O-62(L-5), (1)PT-25, (1)PQ-12
Navy(1922-1962): (1)HO5S, (1)HTK, (1)HTL-2/4/6/7(H-13), (1)HUL(H-13), (1)OY, (2)TDR
Joint(1962+): (2)U-8, (1)U-9B
O-470 Continental Army/AF(1924-1962): (1)L-17(U-18), (1)L-19(O-1), (2)L-27(U-3), (1)T-34A/B
Navy(1922-1962): (1)OE(O-1)
Joint(1962+): (1)O-1, (2)U-3, (1)U-17, (1)U-18
O-480 Lycoming GO-480-B2 Army/AF(1924-1962): (2)L-23D/E/F(U-8), (1)L-26B/C(U-4,U-9), (1)L-28(U-10)
Joint(1962+): (1)U-4B, (2)U-8D/E/F, (1)U-9C, (1)U-10
O-520 Continental Joint(1962+): (2)C-28, (2)T-42, (1)U-17B, (1)U-22, (1)U-26
O-540 Franklin 8-ACGSA-538  
O-540 Lycoming (Textron) Navy(1922-1962): (2)UO(U-11)
Joint(1962+): (1)T-3, (2)U-11
O-550 Continental (Teledyne) GIO-550A Joint(1962+): (2)U-38
O-805 Franklin 12-ACGSA-806 Army/AF(1924-1962): [(2)BQ-5]
O-580 Lycoming Army/AF(1924-1962): (1)H-31
O-1230 Lycoming O-1230-A Army/AF(1924-1962): (1)XA-19A

R-250 General Motors X-250-D  
R-265 Ken-Royce LeBlond 5-G Army/AF(1924-1962): (1)UC-102
R-270 Lambert  
R-370 Ken-Royce LeBlond 7-G Army/AF(1924-1962): (1)UC-102A
R-370 Kinner K-5 Army/AF(1924-1962): (1)PT-6, (1)PT-7
Navy(1922-1962): (1)N2Y
R-420 Warner Scarab Army/AF(1924-1962): (1)C-10
R-440 Kinner B-5 Army/AF(1924-1962): (1)PT-16, (1)PT-20A, (1)PT-21
R-500 Warner Super Scarab Army/AF(1924-1962): (1)C-61, (1)UC-77C/D, (1)C-80, (1)C-94
Navy(1922-1962): (1)GK
R-540 Kinner R-5-2 Army/AF(1924-1962): (1)PT-22
R-540 Wright Whirlwind 5 (J-6) Army/AF(1924-1962): (1)YPT-9, (1)YPT-10/B
R-545 Continental A-70 Army/AF(1924-1962): (1)YPT-9A, (1)YPT-10A, (1)Y1PT-11
R-550 Warner Super Scarab Army/AF(1924-1962): (1)R-4
R-600 Curtiss Challenger Army/AF(1924-1962): (1)PT-5, (1)Y1PT-11A
R-670 Continental R-670-A Army/AF(1924-1962): (1)UC-72D, (1)PT-14, (1)PT-17, (1)PT-23, (1)PT-27
Navy(1922-1962): (1)JW, (1)N2S-1/3/4, (1)N2T
R-680 Lycoming R-680-A Army/AF(1924-1962): (2)AT-8, (2)AT-9, (2)AT-10, (1)AT-19, (1)XBQ-2A, (1)UC-72C, (1)C-81, (3)C-91, (1)L-1, (1)L-12, (1)O-49(L-1), (1)YPT-9B, (1)YPT-10C, (1)PT-11C/D, (1)PT-13, (1)T-31
Navy(1922-1962): (1)NP, (1)NQ, (1)N2S-2/5, (1)N4Y, (1)R3Q
R-720 Kinner C-5 Army/AF(1924-1962): (1)YPT-9C, (1)YPT-10D, (1)PT-11B
R-755 Jacobs L-4 Army/AF(1924-1962): (2)AT-17, (1)UC-43J, (1)UC-72K, (2)C-78, (1)C-126, (1)G-1, (1)PT-18, (1)R-3
Navy(1922-1962): (2)JRC
R-760 Wright Whirlwind 7 (J-6) Army/AF(1924-1962): (1)UC-70C, (1)UC-72B/F, (1)UC-77A, (1)UC-81B/G/H/J, (1)C-88, (1)PT-15
Navy(1922-1962): (1)JK, (1)J2W, (1)N2C, (1)N3N, (1)N5N, (1)NY-3, (1)OO
R-790 Wright Whirlwind 9 (J-5) Army(1919-1924): (1)NO-2
Army/AF(1924-1962): (1)AT-5, (3)C-2, (3)C-3, (1)O-14, (1)O-15, (1)O-17, (1)PT-2, (1)PT-3
Navy(1922-1962): (1)NK, (1)NS, (1)NY, (1)N3Y, (2)XPS-1, (3)TA(RA), (3)RA
R-830 Jacobs L-5 Army/AF(1924-1962): (1)UC-43D/G, (1)UC-70D, (1)UC-72E/H/M/N
R-915 Jacobs L-6 Army/AF(1924-1962): (2)AT-20, (1)UC-43C, (1)UC-70A/B, (1)UC-72A/G/J/L/P, (1)O-60, [(1)O-61], (1)R-2
R-975 Wright Whirlwind 9 (J-6) Army/AF(1924-1962): (1)BT-3, (1)BT-6, (1)BT-9, (1)BT-15, (2)BQ-6, (3)C-7, (3)C-9, (2)C-21, (2)UC-36C, (1)UC-43A/E/F/H/K, (1)UC-77, (1)G-2, (1)H-25, (2)OA-3, (1)V-1
Navy(1922-1962): (1)F9C, (1)HJP(HUP), (1)HJS, (1)HUP, (1)JB, (2)RC, (2)RD, (1)R3O, (1)SNC, (2)TD3R
DR-980 Packard DR-980 Diesel Army/AF(1924-1962): (1)PT-8
R-985 Pratt & Whitney Wasp Junior Army/AF(1924-1962): (2)AT-7, (2)AT-11, (1)BT-5, (1)BT-7, (1)BT-8, [(1)BT-11], (1)BT-12, (1)BT-13, (1)BT-14, (1)BT-16, (1)BT-17, (2)C-26, (1)C-28, (2)C-36, (2)C-37, (2)C-40, (1)C-43, (2)C-45, (1)UC-61D, (1)C-70, (1)UC-71, (1)UC-72, (1)UC-81D/E/F, (2)F-2, (1)L-12A, (1)L-20(U-6), (1)O-51, (2)OA-4, (2)OA-9, (2)OA-13, (1)P-21, (1)PT-12, [(1)PQ-11], (1)R-1, (1)R/H-5, (2)R-10, (1)V-3
Navy(1922-1962): (1)GB, (1)GH, (2)HJH, (1)HO2S, (1)HO3S, (2)J3F(JRF), (2)JO, (1)JQ(RQ), (2)JRB(C-45), (2)JRF, (1)NH, (1)OJ, (1)OK, (1)OS2N, (1)OS2U, (2)R2O, (1)RQ, (2)SNB, (1)SNV
Joint(1962+): (1)U-6
R-1044 Kinner C-7 Navy(1922-1962): (1)RK
R-1300 Wright/Lycoming Army/AF(1924-1962): (1)H-19, (1)T-28A, [(1)T-30]
Navy(1922-1962): (1)HO4S-3(H-19), (1)HRS-3(H-19), (2)ZPG
R-1340 Pratt & Whitney Wasp Army/AF(1924-1962): (1)A-4, (1)AT-6/T-6, (2)AT-13, (2)AT-15, (1)AT-16, (1)BC-1, (1)BC-2, (1)BC-3, (1)BT-2, (1)BT-10, (3)C-4, (3)C-5, (2)C-6, (1)C-8, (1)C-12, (1)C-17, (1)C-19, (1)C-23, (1)C-25, (2)C-29, (2)C-35, (2)UC-36B, (1)C-64, (2)C-73, (1)C-85, (1)C-96, (1)C-101, (2)C-106, (1)F-1, (1)R/H-12, (1)H-19A/C, (1)H-43C/D, (1)L-11, (2)LB-3, (1)O-12, (1)O-19, (1)O-22, [(1)O-24], (1)O-28, (1)O-32, [(1)O-37], (1)O-52, [(2)OA-7], (1)P-3, (1)P-12, (1)XP-13A, (1)P-15, (1)P-26, (1)P-27, (1)P-28, (1)P-29
Navy(1922-1962): (1)FA, (1)FB-6/7, (1)F2B, (1)F3B, (1)F4B, (1)F5B, (1)F7B, (1)F6C-4, (1)F7C, (1)F8C, (1)FG, (1)F2G, (1)FH, (1)FJ, (1)F2U, (1)F3W, (1)HOK(H-43), (1)HO4S-1, (1)HRP, (1)HRS-1, (1)HUK(H-43), (1)JA, (1)JE, (1)J2Q(R2Q), (3)JR-3(RR), (1)NJ, (1)OC, (1)O2C, (1)O3C, (1)OL-8/9, (1)O2L, (1)O2N(OSN), (1)O2U, (1)O3U, (1)O4U, (1)O5U, (1)OSN, (1)OSS, (1)OSU, (2)PJ, (2)P3M-1, (2)PS(RS), (2)P2S, (2)PY, (2)RD-3/4, (1)RE, (1)R2Q, (3)RR-3/4/5, (2)RS, (1)SS, (1)SNJ, (1)SOC, (1)SO2C, (1)SON, (1)UC(U-1), (2)ZSG, (2)ZS2G
Joint(1962+): (1)U-1
R-1454 Curtiss Army/AF(1924-1962): (1)O-8, (1)XP-3
R-1510 Wright Whirlwind 14 Navy(1922-1962): (1)F11C-1, (1)F12C, (1)F13C, (1)F2J, (1)F3J, (1)FT, (1)S2C, (1)S4C, (1)SBC-2
R-1535 Pratt & Whitney Twin Wasp Junior Army/AF(1924-1962): (1)A-17, (1)O-46, [(1)P-32]
Navy(1922-1962): (1)BG, (1)B2G, (1)BT, (1)B2Y, (1)BFB, (1)F6B(BFB), (1)FD, (1)F2F, (1)F3F-1, (1)F3U, (1)XO3U-5, (1)XSF-2, (1)SBC-3, (1)SBU, (1)SB2U, (1)SB3U
H-1640 (note 1) Curtiss Chieftain Army/AF(1924-1962): [(1)A-6], (1)O-18, (1)O-21, (1)P-11, (1)P-13, [(1)P-14]
Navy(1922-1962): (1)XOC-3
R-1670 Wright Army/AF(1924-1962): (2)A-14, [(1)O-48]
R-1690 Pratt & Whitney Hornet A Army/AF(1924-1962): (1)A-10, (2)B-3, (2)B-12, (1)C-14B, (2)C-56A/C/D, (2)C-59, (1)C-89, (2)LB-2, [(2)LB-4], (2)LB-7, (2)LB-10, (2)LB-13, (1)O-20, (1)O-38, (2)OA-8, (2)OA-11
Navy(1922-1962): (1)BM, (1)F6C-5, (2)JRS, (1)O3U-2/4(SU), (2)P3M-2, (2)R5O-2, (1)SU, (1)TG-1, (1)XT3M-3, (1)T4M, (1)T5M
R-1750 Wright Cyclone 9 Army/AF(1924-1962): (2)B-5, (1)C-14, (1)C-15, (2)LB-6, (2)LB-9, (2)LB-11, (1)XO-21A, (1)O-29
Navy(1922-1962): (2)PD, (1)XPH-1, (2)PM-1, (2)PN-11/12, (2)P4N, (2)T2D, (1)XT3M-4, (2)TN, (1)T2N
R-1820 Wright Cyclone 9 Army/AF(1924-1962): (1)A-12, (1)A-13, [(2)A-15], (2)A-18, (1)A-24, (1)A-27, (2)A-29, (1)A-33, (2)AT-18, (2)B-6, (2)B-10, [(2)B-11], (4)B-17, (2)B-18, (4)B-40, (1)C-11A, (1)Y1C-14A, (1)C-15A, (1)C-22, (1)C-24, (1)C-27B/C, (2)C-30, (1)C-31, (2)C-32, (2)C-33, (2)C-34, (2)C-38, (2)C-39, (2)C-42, (2)C-49, (2)C-50, (2)C-51, (4)XC-54K, (2)C-56, (2)C-58, (2)C-60, [(2)C-63], (2)C-68, (4)C-75, (2)C-84, (1)C-100, (1)C-103, (4)C-108, (2)C-110, (2)C-111, (2)C-117D, (2)C-122C, (3)C-125, (4)F-9, (1)H-21, (1)H-34, (1)O-29A, (1)O-38D, (1)O-40, (2)O-44, (2)O-45, (1)O-47, (2)OA-5, [(2)OA-6], (1)OA-12, (1)P-20, (1)P-36G, (2)P-50, (1)P-64, (2)SA-16(U-16), (1)T-28
Navy(1922-1962): (1)BT-2, (1)BY, (1)BFC, (1)BF2C, (1)F2A, (1)F8C-7/8, (1)F10C, (1)F11C, (1)FF, (1)F3F-2/3, (1)F4F-5, (1)F5F, (1)FM-2, [(1)F2M], (1)FN, (1)FR, [(1)HRS-4], (1)HSS-1(H-34), (1)HUS(H-34), (1)JF, (1)J2F, (1)JL, (2)JR2F(UF), (1)O2C-2, (4)PB, (2)P2D, (1)PH, (2)PK, (2)PM-2, (3)P2M, (2)P2Y, (2)PBO, (2)R4C, (2)R2D, (2)R3D, (2)R4D-8(C-117), (1)RO, (2)R5O, (1)RT, (1)SC, (1)S3C, (1)SF, (2)S2F(S-2), (1)SBA, (1)SBC-1/4, (1)SBD, (1)SBN, (1)SN2J, (1)SOE, (2)TF(C-1), (1)TG-2, (2)UF(U-16), (2)WF(E-1)
Joint(1962+): (2)C-1, (2)E-1, (2)S-2, (2)U-16
R-1830 Pratt & Whitney Twin Wasp Army/AF(1924-1962): (1)A-16, (1)A-19, (2)A-22, (2)A-28, (1)AT-12, (4)AT-22, (2)B-14, (4)B-15, (4)B-24, (4)B-41, (2)C-41, (2)C-47, (2)C-48, (2)C-52, (2)C-53, (2)C-57, [(2)C-62], (2)C-66, (2)C-76, (4)C-87, [(2)C-93], [(2)C-104], (4)C-105, (4)C-109, (2)C-117, (4)F-7, (2)OA-10, [(1)P-33], [(1)P-34], (1)P-35, (1)P-36, (1)P-41, (1)P-42, (1)P-43, (1)P-66
Navy(1922-1962): (1)F4F, (1)FM-1, (1)JF-1, (4)JR2S, (2)P3D, (2)P3Y, (2)PB2B, (2)PBN, (4)PBS, (2)PBV, (2)PBY, (4)PB2Y, (4)PB4Y(P4Y,P-4), (2)RB, (2)R4D(C-47), (2)R5O-3, (4)RY, (4)R2Y, (1)XT3D-2, (1)TBD, (1)TBG
Joint(1962+): (4)P-4
R-1860 Pratt & Whitney Hornet B Army/AF(1924-1962): (2)B-4, (2)B-9, [(2)B-13], (1)C-11, (1)C-16, (1)C-18, (4)C-20, (1)C-27, (2)LB-8, (2)LB-12, (2)LB-14
Navy(1922-1962): (1)XT3D-1, (1)T6M
R-2000 Pratt & Whitney Twin Wasp Army/AF(1924-1962): (4)C-54, (2)C-122
Navy(1922-1962): (2)F5U, (4)R5D(C-54)
Army(1955-1962): (2)AC-1(CV-2)
Joint(1962+): (2)C-7, (2)CV-2(C-7)
R-2160 Wright Tornado Army/AF(1924-1962): [(1)P-69]
R-2180 Pratt & Whitney Twin Hornet Army/AF(1924-1962): (2)A-21, [(4)B-20], (2)B-21, (2)H-16, [(1)P-44]
R-2600 Wright Cyclone 14 Army/AF(1924-1962): (2)A-20, (1)A-25, (2)A-30, (1)A-31, [(1)A-34], (1)A-35, (2)AT-24, [(2)B-22], (2)B-23, (2)B-25, [(4)B-33], (2)B-37, (2)C-55, (2)C-67, (4)C-98, (2)F-3, (2)F-10, [(2)O-53], [(2)O-56], [(2)P-65], (2)P-70
Navy(1922-1962): (2)BD, (1)F6F-1, (2)PBJ, (2)PBM, (4)PB2Y-4, (1)SB2A, (1)SB2C, (1)SBF, (1)SBW, (1)TBF, (1)TBM
R-2800 Pratt & Whitney Double Wasp Army/AF(1924-1962): (1)XA-19B, (2)A-26, (1)A-32, [(2)A-37], [(1)A-39], (2)AT-23, (2)B-26, [(2)B-27], (2)B-28, (2)B-34, (2)C-46, (2)C-82, (4)C-112, (4)C-118, (2)C-123, (2)C-131, (2)F-15, (2)H-37, (1)P-47, (1)P-56, [(2)XP-59(not the jet!)], (1)P-60A/C/E, (2)P-61, (2)T-29, [(2)T-32], [(2)T-36]
Navy(1922-1962): (1)AF, (2)AJ(A-2), (1)AU, (1)BTK, (1)F3A, (1)F15C, (1)F6F, (2)F7F, (1)F8F, (1)FG, (1)F3M, (2)F2T, (1)F4U, (2)HR2S(H-37), (1)HSL, (2)JD, (2)JM, (2)PV, (2)PBM-5, [(4)PB3Y], (2)RM(C-3), (2)R5C(C-46), (4)R6D(C-118), (2)R4Y, [(2)TB2F], (1)TB3F, (1)TBU, (1)TBY
Joint(1962+): (2)A-2, (2)C-3
R-3350 Wright Cyclone 18 Army/AF(1924-1962): [(2)A-23], (1)A-31C, (2)A-38, [(1)A-40], (4)B-19, (4)B-29, [(4)B-30], [(4)B-31], (4)B-32, (2)B-69, (2)XC-46L, (4)C-69, (4)XC-97, (2)C-119, (4)C-121, (2)C-128, (2)C-134, (4)F-13, (1)P-62
Navy(1922-1962): (1)AD(A-1), (1)BT2C, (1)BTD, (1)BT2D(AD), (1)F14C-2, (4)JRM, (4)P2B, (2)P5M(P-5), (4)PO(WV), (2)P2V(P-2), (2)P4Y, (2)PBB, [(2)PBM-4], (4)PB2M, (4)R7O(R7V), (2)R4Q-2(C-119), [(1)SB3C], (1)SB2D(BTD), (4)R7V(C-121), (4)WV(C-121)
Joint(1962+): (1)A-1, (2)P-2, (2)P-5
R-4090 Wright 792C22AA  
R-4360 Pratt & Whitney Wasp Major Army/AF(1924-1962): (1)XA-31B, [(1)A-41], (4)B-35, (6)B-36, (4)B-44, (4)B-50, (4)C-74, (4)C-97, (6)C-99, (2)C-119A/B/C, (2)C-120, (4)C-124, (2)F-11, (4)F-12(R-12), [(2)P-71], (1)P-72
Navy(1922-1962): (1)AM, (1)BTC, (1)BTM(AM), (1)F8B, (4)JRM-2, (2)P4M, (4)R6O(R6V), (2)R4Q-1(C-119), (4)R6V, (1)TB2D
R-7755 Lycoming XR-7755  

V-720 Wright Army/AF(1924-1962): (1)AT-1, [(1)AT-2], (1)AT-3, (1)AT-4, (1)PT-1
V-770 Ranger SGV-770B-3 Army/AF(1924-1962): (2)AT-14, (2)AT-21, (2)BQ-3, (1)O-50, (1)P-77
Navy(1922-1962): (1)F6C-7, (1)OSE, (1)SO3C, (1)SO2U, (1)TE
V-1150 Curtiss D-12 Army(1919-1924): (1)PW-7, (1)PW-8, (1)PW-9, (1)R-6, (1)R-8
Army/AF(1924-1962): (1)A-3, (1)BT-4, (1)O-1, (1)P-1, (1)P-5
Navy(1922-1962): (1)F6C-1/2/3/6, (1)MO, (1)M2O, (1)NO, (1)R2C
V-1400 Curtiss Army(1919-1924): (1)NO-1
Army/AF(1924-1962): (1)P-2
Navy(1922-1962): (1)R3C
V-1410 Allison-Liberty IV-1410 Liberty Army(1919-1924): (1)CO-6, (1)XCO-7B
Army/AF(1924-1962): (1)A-2
V-1440 Continental  
V-1460 Wright IV-1460 Army/AF(1924-1962): (1)O-10, (1)XOA-1A, (1)OA-2, (1)P-17
V-1510 Curtiss  
V-1560 Wright IV-1560 Army/AF(1924-1962): [(1)P-18], [(1)P-19]
V-1570 Curtiss Conqueror Army/AF(1924-1962): [(1)A-5], (1)A-7, (1)A-8, [(1)A-9], (1)A-11, (2)B-1, (2)B-2, (2)B-7, (2)B-8, (2)Y1B-9, (1)O-13, (1)O-16, (1)O-23, (1)O-25, (1)O-26, (2)O-27, [(2)O-30], (1)O-31, (1)O-33, (1)O-34, (2)O-35, (2)O-36, (1)O-39, [(1)O-41], (1)O-43, (1)P-6, (1)P-7, (1)P-9, (1)P-10, (1)P-16(PB-1), (1)P-22, (1)P-23, (1)P-24, (1)P-25, (1)P-30(PB-2), (1)P-31, (1)PB-1, (1)PB-2
Navy(1922-1962): (4)P2H
V-1650 Liberty Liberty 12 Army(1919-1924): (1)A-1, (1)A-2, (1)CO-1, (1)CO-2, (1)CO-3, (1)CO-4, (1)CO-5, (1)CO-7, (1)CO-8, (2)GA-1, (1)IL-1, (6)NBL-1, (2)NBS-1, (2)NBS-2, (2)NBS-3, (2)NBS-4, (2)T-1, (1)T-2, (1)T-3
Army/AF(1924-1962): (1)BT-1, (1)C-1, (2)LB-5, (1)O-1A, (1)O-2, [(1)O-4], (1)O-5, (1)O-6, (1)O-11, (1)OA-1
Navy(1922-1962): (1)O2B, (1)OL-4
V-1650 Packard/Rolls-Royce Merlin Army/AF(1924-1962): (4)C-115, (1)F-6, (1)P-40F/L, (1)P-51, (1)XP-60/D, [(1)XP-63B], [(1)P-78], (2)P/F-82/B/C/D/E
V-1710 Allison Army/AF(1924-1962): (1)XA-11A, (1)A-36, (2)A-42, [(6)B-16], (4)B-38, (2)B-42, (4)C-114, (4)C-116, (2)F-4, (2)F-5, (1)F-6A, (2)FM-1, (1)P-37, (2)P-38, (1)P-39, (1)P-40, (1)P-45, (1)P-46, [(1)XP-47/A], (1)P-51/A/J, (1)P-55, (1)XP-60A/B, (1)P-63, [(1)P-76], (2)P/F-82A/F/G/H
Navy(1922-1962): (1)FL, (1)FO
V-1950 Wright T-3 Army/AF(1924-1962): [(1)O-3]
V-3420 Allison Army/AF(1924-1962): (4)B-39, (2)P-58, (1)P-75

Notes:

1. The Curtiss Chieftain engine was of a unique configuration, and was originally classed as a "hexagonal" engine - hence the "H" prefix. It was later redesignated as the R-1640 radial engine.

3 Jet and Turbine Engines, 1946 - 1968

After World War II, the Army and the Navy defined a system for designating gas turbine and other jet engines. The system was formally laid down in Air Force/Navy Aeronautical (ANA) Bulletin 306. This ANA Bulletin was updated several times, the final edition being ANA Bulletin 306M, dated 27 December 1963. On 1 May 1968, a revised system was defined by MIL-STD-879. The latter was finally absorbed into the current standard MIL-STD-1812 on 28 February 1991.

Examples: Y T 56 - A - 1
J 35 - A - 21 C
(6) (1) (2) (3) (4) (5)

The one- or two-letter code (1) designates the type of the engine:

(2) is the model number of the engine. Note that there is no dash between the engine type letter and the model number. The Army and Air Force used odd numbers from 31 up, while the Navy used even numbers from 30 up. Why each numerical sequence was started at 30, I don't know. The numbers were assigned in numerical sequence separately by each service, so the Navy-sponsored J52 was in fact a later engine than the J65, because Navy J-numbers "lagged behind" the Army/AF ones.

(3) is a one- or two-letter code for the manufacturer of the engine. The following is a list of all assigned code letters, not all of which were actually used for jet engines:

The same code letters were used in serial numbers for all types of engines, including piston and rocket engines. This explains why code letters were also assigned to companies which never developed or manufactured jet or turbine engines.

The number (4) designates a specific model of the engine. The Army and Air Force use odd numbers from 1 up, while the Navy uses even numbers from 2 up.

(5) is an optional letter for designating minor modifications of an engine model. Letters are assigned alphabetically from A on (I and O are not used). The letter W is reserved for engines with water injection, while the combination "WA" is used for engines with water-alcohol injection.

(6) is an optional status prefix:

Designation List:

Designation Manufacturer and Model Remarks; Aircraft
J30 Westinghouse 19XB Army/AF(1924-1962): (2)XP-79B, [(1)XF-92], (2)X-4
Navy(1922-1962): (2)FH
J31 General Electric I-16 Army/AF(1924-1962): (2)P-59
Navy(1922-1962): (1)FR, (1)F2R
J32 Westinghouse 9.5A/B Navy(1922-1962): (1)KDN
J33 General Electric/Allison I-40 Army/AF(1924-1962): (1)P/F-80, (1)P-81, (2)P-83, (1)XF-92A, (1)F-94A/B, (1)T-33
Navy(1922-1962): (1)AJ(A-2), (1)F9F-3/4, (2)P4M, (1)TO(TV), (1)TV(T-33), (1)T2V(T-1)
Joint(1962+): (1)A-2, (1)T-1
Missiles: (1)TM-61(MGM-1), (1)TM-76(CGM-13), (1)SSM-N-8(RGM-6)
J34 Westinghouse 24C Army/AF(1924-1962): (2)B-69, (1)P/F-85, (4)P/F-87, (2)F-88, (2)F-90, (2)X-3, (1)X-18
Navy(1922-1962): (2)F3D(F-10), (2)F2H(F-2), (1)FR-4, (1)F6U, (2)F7U-1/2, (1)XF2Y-1, (2)P2V-5F/6F/7(P-2), (1)T2J-1(T-2)
Joint(1962+): (1)F-2, (2)F-10, (2)P-2E/G/H/J, (1)T-2A
Other: (1)Douglas D-558-2
J35 General Electric/Allison TG-180 Army/AF(1924-1962): (2)B-43, (4)XB-45, (4)B-46, (4)B-48, (8)B-49, (2)H-17, (1)P/F-84, (1)XP-86, (2)F-89, (1)F-96, (2)X-5
Navy(1922-1962): (1)FJ-1
Other: (1)Douglas D-558-1
J36 Allis-Chalmers (DeHavilland Goblin) Navy(1922-1962): (1)F15C
J37 Lockheed L-1000  
J38 West Engineering  
J39 General Electric I-20 (similar to J31; cancelled)
J40 Westinghouse 40E Army/AF(1924-1962): (2)X-10
Navy(1922-1962): (2)XA3D-1, (1)XF4D-1, (1)F10F, (1)F3H-1
J41 Packard PT-104/PT-4000 (cancelled project)
J42 Pratt & Whitney (Rolls-Royce Nene) Navy(1922-1962): (1)F9F-2
J43 Westinghouse (became XJ30-WE-8)
J44 Fairchild Army/AF(1924-1962): (2)C-123J, (1)Q-1, (1)Q-3
Navy(1922-1962): (1)KDA-1
J45 Westinghouse (became XJ34-WE-4)
J46 Westinghouse 24C Navy(1922-1962): (2)F7U-3, (2)YF2Y-1
J47 General Electric TG-190 Army/AF(1924-1962): (4)B-36D/E/F/H/J, (4)B-45, (6)B-47, (2)KB-50J/K, (3)B-51, (2)KC-97L, (1)F-86, (1)F-91, (1)F-95(F-86D)
Navy(1922-1962): (1)FJ-2
J48 Pratt & Whitney JT7 Army/AF(1924-1962): (1)F-93, (1)F-94C, (1)F-97(F-94C)
Navy(1922-1962): (1)F9F-5/6/7/8(F-9)
Joint(1962+): (1)F-9
J49 Packard PT-205 (cancelled project)
J50 Westinghouse  
J51 Wright TJA-1 (cancelled project)
J52 Pratt & Whitney JT8 Navy(1922-1962): (1)A4D(A-4), (2)A2F(A-6)
Joint(1962+): (1)A-4, (2)A-6
Missiles: (1)GAM-77(AGM-28)
J53 General Electric Army/AF(1924-1962): [(4)X-6]
J54 Westinghouse (Rolls-Royce Avon)  
J55 Flader 124 Army/AF(1924-1962): [(1)Q-2]
J56 Allison  
J57 Pratt & Whitney JT3 Army/AF(1924-1962): (8)B-52, (2)RB-57D, (8)B-60, (4)C-135A, (1)F-100, (2)F-101, (1)F-102, [(2)X-16]
Navy(1922-1962): (2)A3D(A-3), (1)F4D(F-6), (1)F5D, (1)F8U(F-8)
Joint(1962+): (2)A-3, (1)F-6, (1)F-8, (1)U-2A/B/E
Missiles: (1)SM-62
J58 Pratt & Whitney JT11D Joint(1962+): (2)F-12, (2)SR-71
J59 Wright TJ-7 (cancelled project)
J60 Pratt & Whitney JT12 Army/AF(1924-1962): (2)RB-57F, (4)C-140, (2)T-39, [(2)T-40]
Navy(1922-1962): (2)T2J-2(T-2), (2)T3J(T-39)
Army(1955-1962): (2)VZ-10(V-4)
Joint(1962+): (2)H-59, (2)T-2B, (2)XV-4A
J61 Wright TJ-6 (cancelled project)
J62 up (even) Most probably not assigned
J63 Fairchild  
J65 Wright (Armstrong-Siddeley Sapphire) Army/AF(1924-1962): (2)B-57, (1)F-84F, (1)XF-104
Navy(1922-1962): (1)A4D-1/2(A-4), (1)FJ-3/4(F-1), (1)F11F(F-11)
Joint(1962+): (1)A-4A/B/C/L/P/Q, (1)F-1, (1)F-11
J67 Wright (Bristol Olympus) Army/AF(1924-1962): [(4)B-59], [(1)F-103]
J69 Continental 352 Army/AF(1924-1962): (1)Q-1A/B, (2)T-37
Navy(1922-1962): (2)TT
Army(1955-1962): (3)VZ-9
Joint(1962+): (2)A-37A
Missiles: (1)GAM-67, (1)AQM/BQM-34, (1)AQM-103
J71 Allison Army/AF(1924-1962): [(4)B-56], (2)B-66, (2)YF-89E
Navy(1922-1962): (1)F3H(F-3), (4)P6M-1
Joint(1962+): (1)F-3
J73 General Electric Army/AF(1924-1962): (1)F-86H
Navy(1922-1962): [(1)F3H-3]
J75 Pratt & Whitney JT4 Army/AF(1924-1962): (1)F-105, (1)F-106, (1)F-107
Navy(1922-1962): (1)F8U-3, [(2)F2Y-2], (4)P6M-2
Joint(1962+): (1)TR-1, (1)U-2C/D/F/G/H/R
J77 General Electric  
J79 General Electric X-24A Army/AF(1924-1962): (4)B-58, (1)F-104, (2)F-110(F-4), (2)X-21
Navy(1922-1962): (2)A3J(A-5), (2)F4H(F-4), (1)F11F-1F
Joint(1962+): (2)A-5, (2)F-4, (1)F-21
Missiles: (1)SSM-N-9(RGM-15)
J81 Westinghouse (Rolls-Royce Soar) Army/AF(1924-1962): (1)Q-4(AQM-35)
Missiles: (1)AQM-35
J83 Fairchild Missiles: (1)SM-73
J85 General Electric CJ610 Army/AF(1924-1962): (2)C-119K, (2)C-123K, (1)Q-4B(AQM-35B), (2)T-38, (2)X-14
Army(1955-1962): (2)VZ-11(V-5)
Joint(1962+): (2)A-37B, (2)F-5, (2)T-2C/D/E, (6)XV-4B, (2)V-5
Missiles: (1)GAM-72(ADM-20), (1)AQM-35B, (1)MQM-34D
Other: (2)Lockheed "HAVE BLUE"
J87 General Electric X-211 (nuclear powered engine; cancelled)
J89 Allison (low-bypass turbofan engine; unsuccessful competitor to J93 for use in B-70)
J91 Pratt & Whitney JTN9 (higher-bypass turbofan engine; unsuccessful competitor to J93 for use in B-70; also considered as a nuclear engine)
J93 General Electric 7E Army/AF(1924-1962): (6)B-70, [(2)F-108]
LJ95 (note 1) Teledyne CAE 365  
J97 General Electric GE1 Missiles: (1)AQM-91, (1)GQM-94
J99 Rolls-Royce Other: Grumman 754 RPV

T30 Westinghouse  
T31 General Electric TG-100 Army/AF(1924-1962): (2)C-113, (1)P-81
Navy(1922-1962): (1)F2R
T32 Pratt & Whitney  
T33 Flader Brigadier (cancelled project)
T34 Pratt & Whitney PT2 Army/AF(1924-1962): (4)YC-97J, (4)YC-121F, (4)YC-124B, (4)C-133
Navy(1922-1962): (4)R7V-2(C-121)
T35 Wright (cancelled project)
T36 Chrysler  
T37 Northrop Turbodyne Army/AF(1924-1962): [(4)EB-35B]
T38 Allison 501F-1 Army/AF(1924-1962): (1)F-88B, (2)H-27(YH-16A), [(2)T-29E]
T39 Allison 504 (cancelled project)
T40 Allison 500 Army/AF(1924-1962): (1)XF-84H, (2)X-18
Navy(1922-1962): (1)A2D, (2)A2J, (1)FV, (1)FY, [(2)P3B], (4)P5Y, (4)R3Y
T41 General Electric TG-110 (derivative of T31; project cancelled)
T42 De Laval  
T43 Wright GTC-1 (cancelled project)
T44 Allison 503 (cancelled project; similar to T40, but with 3 instead of 2 power sections)
T45 Pratt & Whitney PT4 (cancelled project)
T46 Fairchild  
T47 Wright  
T48 Pratt & Whitney  
T49 Wright TP51A2 Army/AF(1924-1962): (2)XB-47D
T50 Boeing 502-2E Army/AF(1924-1962): (1)XL-19B, (1)QH-50
T51 Continental 220 Army/AF(1924-1962): (1)XH-13F, (1)H-39, (1)XL-19C
T52 Pratt & Whitney  
T53 Lycoming LTC1 Army/AF(1924-1962): (1)H-40, (1)H-43
Navy(1922-1962): (2)OF(OV-1)
Army(1955-1962): (1)VZ-2, (1)VZ-3 (1)VZ-4
Joint(1962+): (1)H-1, (2)OV-1
T54 Allison (Twin T56)
Navy(1922-1962): [(1)XFV-2]
T55 Lycoming LTC4/AL55 Army/AF(1924-1962): (1)YAT-28E, (2)H-47, (2)X-19
T56 Allison 501D Army/AF(1924-1962): (4)C-130, (2)C-131C/H, (2)YH-16B
Navy(1922-1962): [(2)HRH], (2)W2F(E-2), (4)P3V(P-3)
Joint(1962+): (2)C-2, (2)E-2, (4)P-3
T57 Pratt & Whitney PT5 Army/AF(1924-1962): [(4)C-132]
T58 General Electric CT58 Army/AF(1924-1962): (2)H-21D, (2)SH-34H, (2)H-46, (1)H-48
Navy(1922-1962): (2)HRB(H-46), (2)HSS-2(H-3), (1)HU2K(H-2), (1)HU2S(H-52)
Army(1955-1962): (1)VZ-5
Joint(1962+): (1)UH-1F/P, (1)UH-2A/B, (2)H-2, (2)H-3, (1)H-52, (4)X-22
(T59) (No information)
T60 Boeing  
T61 Allison  
T62 Solar Mercury  
T63 Allison 250 Army/AF(1924-1962): (1)UH-13R
Navy(1922-1962): (1)HUL-1M
Joint(1962+): (1)H-4, (1)H-6, (1)H-57, (1)H-58, (1)H-67, (1)V-11
T64 General Electric Army/AF(1924-1962): (4)C-142
Joint(1962+): (2)C-27, (2)H-53, (3)H-53E, (1)H-56, (2)V-9
T65 Continental TS325-1  
T66 Solar  
T67 Continental 217A-2A  
T68 Rolls-Royce  
T69 Continental  
T70 Westinghouse  
T71 Allison  
T72 Continental  
T73 Pratt & Whitney JFTD12 Joint(1962+): (2)H-54
T74 Pratt & Whitney PT6 Joint(1962+): (2)U-21E/G (see note 2)
T75 up (odd) Most probably not assigned
T76 Garrett-AiResearch TPE331 Joint(1962+): (2)C-26, (1)U-23, (2)OV-10
T78 Allison 545 (development only, not flown)
T80 Allison (cancelled project)

(PJ30) (No information)
PJ31 Ford Army(1924-1962): (1)JB-2(LTV-A-1), (1)JB-4, (1)JB-10
Navy(1922-1962): (1)KGW(KUW,LTV-N-2)
Missiles: (1)LTV-A-1, (1)LTV-N-2
PJ32 Solar Navy(1922-1962): (1)KD2G
PJ33 Giannini  
(PJ34) (No information)
PJ35 Giannini  
(PJ36) (No information)
PJ37 Giannini  
(PJ38) (No information)
PJ39 Giannini Army/AF(1924-1962): (1)XQ-1
PJ40 Marquardt  
(PJ41) (No information)
PJ42 McDonnell  
(PJ43) (No information)
(PJ44) (No information)
(PJ45) (No information)
PJ46 Marquardt Navy(1922-1962): (1)KD5G
(PJ47) (No information)
(PJ48) (No information)
PJ49 American Helicopter Army/AF(1924-1962): (2)H-26

RJ30 Marquardt C-20 Navy(1922-1962): (1)KDM
RJ31 Marquardt C-30  
(RJ32) (No information)
(RJ33) (No information)
RJ34 Marquardt  
RJ35 Continental (cancelled project)
(RJ36) (No information)
RJ37 Menasco A-J-20 (cancelled project)
(RJ38) (No information)
RJ39 Marquardt C-48  
RJ40 Pratt & Whitney  
RJ41 Wright  
RJ42 up (even) Most probably not assigned
RJ43 Marquardt Army/AF(1924-1962): (1)X-7
Missiles: (1)IM-99
Other: (1)Lockheed D-21
RJ45 Continental R-20 (cancelled project)
RJ47 Wright Army/AF(1924-1962): (1)X-7
Missiles: (2)SM-64(Sustainer)
RJ49 Continental (cancelled project)
RJ51 Wright  
(RJ53) (No information)
RJ55 Wright Army/AF(1924-1962): [(1)F-103]
RJ57 Marquardt  
RJ59 Marquardt Other: [(2)Convair "Kingfish"]

TF30 Pratt & Whitney JTF10A Army/AF(1924-1962): (2)F-111
Navy(1922-1962): [(2)F6D]
Joint(1962+): (1)A-7, (2)F-14, [(1)X-27]
TF31 General Electric X-84 (proposed for OXCART (Lockheed A-12); cancelled)
TF32 Allison (competitor to TF34; cancelled)
TF33 Pratt & Whitney JT3D Army/AF(1924-1962): (8)B-52H, (2)RB-57F, (4)C-135, (4)C-137, (4)C-141
Joint(1962+): (4)C-18, (4)C-24, (4)E-3, (4)E-8
TF34 General Electric CF34 Joint(1962+): (2)A-10, (2)S-3
Missiles: [(1)GQM-94B]
TF35 General Electric (derivative of Model CJ 805-23)
TF36 up (even) Most probably not assigned
TF37 General Electric CF700  
TF39 General Electric CTF39 Joint(1962+): (4)C-5
TF41 Allison Joint(1962+): (1)A-7D/E/H/K

Notes:

1. "LJ" probably means "Lift Jet". I don't know for sure, whether the LJ95 really fits into the J-sequence, but considering the high number (making a separate LJ-series unlikely) and the fact, that J95 would be missing otherwise, I risk a guess.

2. It seems, that only the basic PT6 engine is designated as T74. Many aircraft use the PT6A version, which is always (exception: T101 for C-23, see below) listed as such in official military documents and data sheets. Aircraft using the PT6A are:
Army/AF(1924-1962): (1)T-34C
Joint(1962+): (2)C-6, (4)RC-7B, (2)C-12, (4)O-5, (1)T-6, (2)T-44, (2)U-21, (1)U-24, (1)U-27, (2)V-18, (1)V-20
Missiles: (1)GQM-93

4 Rocket Engines

4.1 Liquid Fuel Rockets

The designation system for liquid fueled rockets was originally devised in the 1940's and formally defined in Air Force/Navy Aeronautical (ANA) Bulletin 352 (25 June 1948), later included in MIL-STD-815 (USAF only, 14 June 1962) and finally absorbed into the current standard MIL-STD-1812 (28 February 1991). The system (the familiar "LR" designations) has gone through all this essentially unchanged and is discussed in section 5.2 about current rockets. The only difference in the original 1948 system was, that odd model numbers were reserved for the Air Force and Army, while the Navy used only even model numbers. This is similar to early jet engine designations, except that for liquid rockets, the sequence started at 1 instead of 30.

4.2 Solid Fuel Rockets

The original designation system for solid rockets was completely different from today's system and was defined in Air Force/Navy Aeronautical (ANA) Bulletin 353 (22 July 1948). This designation system was abandoned in the 1960's. The Air Force created a new scheme, very similar to that for liquid rockets, and included it in MIL-STD-815 (14 June 1962). The latter system was finally absorbed into the current standard MIL-STD-1812 and is discussed in section 5.2 about current rockets. After abandoning ANA Bulletin 353, the Navy used its MARK/MOD nomenclature system, while the Army used its Ordnance Number nomenclature.

The original (ANA Bulletin 353) designations for solid rocket motors looked like this:

Example: 1.8 KS 7800
(1) (2) (3)

The number (1) is the burn time of the motor in seconds.

The two-letter code (2) indicates the type of propellant. The type codes were assigned by the Solid Propellant Information Agency (SPIA).

Number (3) is the thrust of the motor in pounds.

Note: There are no dashes and blanks between the three elements of the designation.

5 The Current System (MIL-STD-1812A)

On 28 February 1991, MIL-STD-1812 became formally effective. This standard combined several equipment designation systems, which shared common definitions and procedures, into a single document. Included were the type designation systems for all aerospace engines. On 14 February 1997, MIL-STD-1812 was renamed as MIL-HDBK-1812. The change from "Standard" to "Handbook" meant, that the use of the designation systems was no longer mandatory. This "legalized" the long standing practice of using manufacturers' designations for commercial equipment procured "off the shelf". Otherwise, MIL-HDBK-1812 was identical to MIL-STD-1812. However, on 9 October 2020, the document was again renamed to a mandatory "Standard", MIL-STD-1812A. It is essentially identical to MIL-HDBK-1812, but adds the engine type "A".

5.1 Air-Breathing Engines

For turbine engines, the MIL-STD-879 system (now absorbed by MIL-STD-1812) has not changed a lot from the previous system defined in ANA Bulletin 306. The engine type designators and model numbering methods were just revised a little bit. Piston engines, however, are no longer supposed to use the displacement-based designations, but this seems to be a purely theoretical change, because no new piston engines are developed specifically for the military market and new commercial piston engines are operated with their manufacturers' designations. The latter is probably done, because the major American manufacturers of modern piston engines give their engines designations closely following the original "arrangement-displacement" system.

Examples: Y F 119 - PW - 100
T 700 - GE - 701 C
(6) (1) (2) (3) (4) (5)

The letter (1) designates the type of the engine:

I don't know any engine designated in this system with an "O", "R", "V", "C" or "P" designation.

(2) is the model number of the engine. Note that there is no dash between the engine type letter and the model number. The Air Force uses model numbers 100 to 399, the Navy uses 400 to 699 and the Army uses 700 to 999. The numbers are assigned in numerical sequence separately by each service.
The T800 designation for the engine of the Army's RAH-66 Comanche is therefore not strictly conforming to the system, because the Army apparently started a new sequence at 800. Instead, it should have been designated T704 (or whatever the next available number was).

(3) is a two-letter code for the manufacturer of the engine. A few three-letter codes are assigned to non-US manufacturers or joint-venture companies. The following is a list of all assigned code letters (the same letters are used for rocket engine designations), including those which are obsolete now and no longer listed in the latest standard.

Of course, new letters may be assigned, when companies change names, merge or found special joint-venture companies.

The number (4) designates a specific model of the engine. The same method for assignment as for the basic model numbers applies: The Air Force uses numbers 100 to 399, the Navy uses 400 to 699 and the Army uses 700 to 999. It is possible, that an Air Force engine, when used by the Navy, gets a Navy model number, e.g. F110-GE-400.
If a new model of an engine designated within the "old" numerical sequence is procured, model suffixes from the "new" system may be assigned. This results in designations like T64-GE-416A. For the first such assigment, usually the next available number in the "old" model series is taken and added to the "base block number" of the relevant service, e.g. T55-L-11 was followed by T55-L-712.

(5) is an optional letter for designating minor modifications of an engine model. Letters are assigned alphabetically from A on (I and O are not used). The letter W is reserved for engines with water injection.

(6) is an optional status prefix:

Designation List:

Designation Manufacturer and Model Remarks; Aircraft
J100 Teledyne CAE Missiles: (1)AQM-34P/Q/R
J101 General Electric GE15 Joint(1962+): (2)F-17
J102 Allison (supersonic missile engine)
J400 Williams WR24 Joint(1962+): (3)X-48
Missiles: (1)BQM/MQM-74, (1)AGM-154D/E
J401 Garrett AiResearch  
J402 Teledyne CAE 370/372/373 Missiles: (1)AGM-84, (1)MQM-107, (1)BQM-108, (1)AGM/RGM/UGM-109, (1)AGM-158, (1)AGM-159
J403 Microturbo TRI 60-3 Missiles: (1)BQM-126
J700 Teledyne CAE 312 Missiles: (1)ADM-141B/C

T100 Sunstrand  
T101 Pratt & Whitney PT6A-45A Joint(1962+): (2)C-23
T400 Pratt & Whitney PT6T Joint(1962+): (1)AH-1J/T, (1)UH-1N/Y, (1)H-59
(T401) (No information)
(T402) (No information)
(T403) (No information)
(T404) (No information)
T405 Avco Lycoming PLT27 (derivative of AGT-1500 engine of XM1 tank; evaluated for LAMPS III competition)
T406 Allison AE1107 Joint(1962+): (2)V-22
T407 General Electric GE38 Joint(1962+): [(4)P-7]
T408 General Electric (evaluated for LAMPS III competition)
T700 General Electric GE12 Joint(1962+): (2)AH-1W/Z, (2)SH-2G, (2)H-60, (2)H-61, (2)H-63, (2)H-64
T701 Allison 501-M62 Joint(1962+): [(3)H-62]
T702 Avco Lycoming LTS101 Joint(1962+): (2)H-65
T703 Allison 250 (improved T63)
Joint(1962+): (1)OH-58D
(T704) (No information)
(T705) (No information)
(T706) (No information)
(T707) (No information)
T708 General Electric  
T800 LHTEC Joint(1962+): (2)H-66

F100 Pratt & Whitney JTF22 Joint(1962+): (1)YA-7F, (2)F-15, (1)F-16
F101 General Electric Joint(1962+): (4)B-1
F102 Avco Lycoming ALF502 Joint(1962+): (2)A-9, (4)XC-8A
F103 General Electric CF6 Joint(1962+): (3)C-10, (2)C-14, (4)C-25, (4)E-4
F104 Garrett ATF3 Joint(1962+): (2)U-25
Missiles: (1)GQM-98
F105 Pratt & Whitney JT9D Joint(1962+): (4)E-4A
F106 Teledyne(?)  
F107 Williams Missiles: (1)AGM-86, (1)BGM-109
F108 CFM CFM56 Army/AF(1924-1962): (4)KC-135R/T
Joint(1962+): (2)C-40, (4)E-3F, (4)E-6
F109 Garrett TFE76 Joint(1962+): (2)T-46, [(2)T-48]
F110 General Electric Joint(1962+): (2)F-14B/D, (1)F-16C/D
(F111) (No information)
F112 Williams Joint(1962+): (1)X-36, (1)X-50
Missiles: (1)AGM-129
F113 Rolls-Royce Mk.511 Spey Joint(1962+): (2)C-20
(F114) (No information)
(F115) (No information)
(F116) (No information)
F117 Pratt & Whitney PW2037 Joint(1962+): (4)C-17
F118 General Electric Joint(1962+): (4)B-2, (1)U-2S
F119 Pratt & Whitney PW5000 Joint(1962+): (2)F-22, (2)YF-23A
F120 General Electric GE37 Joint(1962+): (2)YF-22A, (2)YF-23A
F121 Williams Missiles: (1)AGM-136
F122 Williams Missiles: (1)AGM-137
(F123) (No information)
F124 Garrett TFE1042, TFE1088-16 Joint(1962+): (1)X-45A
Czech Rep.: (1)Aero L-159
F125 Garrett TFE1042-70 (no US aircraft)
Taiwan: (2)AIDC Ching Kuo
F126 Rolls-Royce Mk.611/661 Tay Joint(1962+): (2)C-20F/G/H
F127 General Electric (derivative of J101/F404 for export; cancelled)
F128 General Electric (derivative of J101/F404 for export; afterburning version of F127; cancelled)
F129 Williams FJ44 Joint(1962+): (1)Q-3
F130 Rolls-Royce BR725 Joint(1962+): (8)B-52J
(F131) (No information; probably not assigned)
(F132) (No information; probably not assigned)
(F133) (No information; probably not assigned)
(F134) (No information; probably not assigned)
F135 Pratt & Whitney Joint(1962+): (1)F-35, (1)X-32, (1)X-35
F136 General Electric Joint(1962+): (1)F-35
F137 Rolls-Royce/Allison AE3007H Joint(1962+): (1)Q-4
F138 General Electric CF6-80C2L1F Joint(1962+): (4)C-5A/B (re-engined), (4)C-5M
F139 Pratt & Whitney PW4062-3 Joint(1962+): (2)KC-46
F400 General Electric  
F401 Pratt & Whitney JTF22 Joint(1962+): (2)YF-14B, (1)FV-12
F402 Rolls-Royce Pegasus Joint(1962+): (1)AV-8
(F403) (No information)
F404 General Electric Joint(1962+): (2)A-6F, (2)F-18, (1)F-20, (2)F-117, (1)X-29, (1)X-31, (1)X-45B
F405 Rolls-Royce/Turbomeca Adour Joint(1962+): (1)T-45
(F406) (No information)
(F407) (No information)
F408 Teledyne CAE 382 Missiles: (1)BQM-145
(F409) (No information)
(F410) (No information)
(F411) (No information)
F412 General Electric (improved F404)
Joint(1962+): [(2)A-12]
(F413) (No information)
F414 General Electric (improved F412)
Joint(1962+): (2)F-18E/F
F415 Williams Missiles: (1)RGM/UGM-109E/H
F700 General Electric  

A100 General Electric (proposed for F-35 engine replacement)
A101 Pratt & Whitney (proposed for F-35 engine replacement and NGAD fighter)
A102 General Electric (proposed for NGAD fighter)
A103 Pratt & Whitney (proposed for NGAD fighter)

5.2 Rocket Engines

Rocket engines are assigned designations similar to air-breathing engines, except that the model numbering does not indicate the developing service any more. In fact, only the Air Force seems to use the LR/SR rocket designators nowadays. Navy rocket engines and motors are usually designated in the Navy's MARK/MOD numbering system, while the Army uses its Ordnance Number nomenclature.

Examples: X LR 99 - RM - 1
SR 110 - AD - 1
(6) (1) (2) (3) (4) (5)

The letter (1) designates the type of the engine:

(2) is the model number of the engine. Note that there is no dash between the engine type letter and the model number. Each rocket type uses a separate numerical sequence, starting from 1. The original method to assign odd numbers to Air Force engines and even numbers to Navy engines has been discarded.

(3) is a two-letter code for the manufacturer of the engine. The listing of currently defined manufacturer codes can be found in the section about air-breathing engines.

The number (4) designates a specific model of the engine. Numbers are assigned in numerical sequence, starting from 1.

(5) is an optional letter for designating minor modifications of an engine model. Letters are assigned alphabetically from A on (I and O are not used).

(6) is an optional status prefix:

Designation List:

Unfortunately, my list of rocket engine designations is still very incomplete. I don't know any actual designations in the "LSR" series, and the SR list has numerous gaps. Therefore, I have omitted the usual "(No information)" entries for the gaps in the latter, and have listed only designations known to me.
Because very few manned aircraft used rocket propulsion, I have ommitted the "Missiles:" designation system prefix for all missiles listed in the "Aircraft" column.

Designation Manufacturer and Model Remarks; Aircraft
LR1 Aerojet 25-AL-1000 (RATO rocket for A-20)
LR2 Reaction Motors  
LR3 Aerojet 25-ALD-1000 (Droppable RATO rocket for B-25J)
(LR4) (No information)
LR5 Aerojet X40-ALD-3000 (Droppable RATO rocket)
LR6 Reaction Motors (1)SAM-N-2, (1)CTV-N-9
LR7 Aerojet XCALT-6000  
LR8 Reaction Motors Army/AF(1924-1962): (1)X-1E
Other: (1)Douglas D-558-2
LR9 Aerojet X4-AL-1000 (Brake rocket for G-4A)
LR10 Reaction Motors (1)RTV-N-12
LR11 Reaction Motors Army/AF(1924-1962): (1)F-91, [(1)XF-92], (1)X-1
Joint(1962+): (1)X-24
(LR12) (No information)
LR13 Aerojet X60-ALD-4000 (RATO rocket for B-29, B-45)
(LR14) (No information)
LR15 Aerojet XCNLT-1500  
LR16 Aerojet  
LR17 Curtiss-Wright (RATO rocket for XB-45)
(LR18) (No information)
LR19 Curtiss-Wright  
LR20 Aerojet (1)SAM-N-2/4
LR21 Curtiss-Wright (cancelled project)
LR22 Reaction Motors  
LR23 Aerojet X90-ALT-60000  
LR24 Aerojet (1)SAM-N-2/4
LR25 Curtiss-Wright Army/AF(1924-1962): (1)X-2
LR26 Reaction Motors  
LR27 Curtiss-Wright (planned for XF-91; cancelled)
(LR28) (No information)
LR29 Curtiss-Wright (cancelled project)
LR30 Reaction Motors (planned for X-15; cancelled)
LR31 M.W. Kellogg (cancelled project)
LR32 Reaction Motors Army/AF(1924-1962): XH-15(blade-tip engine)
LR33 Reaction Motors (cancelled project)
LR34 Reaction Motors (helicopter blade-tip engine)
LR35 Reaction Motors (1)RTV-A-2
(LR36) (No information)
LR37 Curtiss-Wright  
(LR38) (No information)
LR39 Reaction Motors  
LR40 Reaction Motors Navy(1922-1962): [(1)F8U-3F]
LR41 North American  
LR42 North American Navy(1922-1962): (1)FJ-4F
LR43 North American Army/AF(1924-1962): [(1)X-11], [(3)X-12]
LR44 Thiokol TD-174 (1)AAM-N-6, (1)GAM-79
LR45 Aerojet AJ24-1 (RATO rocket; planned for F-84 and cancelled B-47C(B-56))
LR46 North American (derivative of LR42 planned for A3J)
LR47 M.W. Kellogg SPD 649-1 (RATO rocket; planned for cancelled B-47C(B-56))
LR48 Reaction Motors  
LR49 Aerojet (RATO rocket)
LR50 General Electric X-405 (1)Vanguard(1st stage)
LR51 Aerojet  
LR52 Aerojet AJ-10 (1)Vanguard(2nd stage)
LR53 Aerojet (Booster rocket planned for F-80)
LR54 North American (derivative of LR42)
Navy(1922-1962): [(1)F8U-1F]
LR55 North American (2.75" rocket)
LR56 Aerojet Navy(1922-1962): [(1)F8U-3F]
(LR57) (No information)
LR58 Thiokol TD-187 (1)AGM-12B, (1)AGM-83
LR59 Aerojet (1)IM-99
(LR60) (No information)
(LR61) (No information)
LR62 Thiokol TD-232 (1)AGM-12C/E
LR63 Aerojet (RATO/Booster rocket planned for F-84 and F-86)
LR64 Rocketdyne (1)AQM-37
LR65 Bell Army/AF(1924-1962): (1)X-9
LR66 ... LR130 (even) Most probably not assigned
LR67 Bell (1)GAM-63
(LR69) (No information)
LR71 North American (1)XSM-64(Booster)
LR73 Aerojet  
LR75 M.W. Kellogg (RATO rocket; derivative of LR47)
(LR77) (No information)
LR79 Rocketdyne S-3D (1)SM-75(PGM-17), (1)SM-78(PGM-19)
LR81 Bell (1)RM-81
LR83 North American [(1)XSM-64A(Booster)]
LR85 Aerojet (1)GAM-71
LR87 Aerojet (2)SM-68(LGM-25)(1st stage)
LR89 Rocketdyne (2)SM-65(CGM-16)(Booster)
LR91 Aerojet (1)SM-68(LGM-25)(2nd stage)
(LR93) (No information)
(LR95) (No information)
(LR97) (No information)
LR99 Reaction Motors Army/AF(1924-1962): (1)X-15
LR101 Rocketdyne (2)SM-65(CGM-16)(Vernier), SM-75(PGM-17)(Vernier)
(LR103) (No information)
LR105 Rocketdyne (1)SM-65(CGM-16)
LR107 Hughes Tool Co.  
(LR109) (No information)
(LR111) (No information)
LR113 Aerojet  
LR115 Pratt & Whitney RL-10-A-1 (2)SSB-8
(LR117) (No information)
LR119 Pratt & Whitney RL-10-A-3 (planned for Saturn; cancelled)
LR121 Rocketdyne Army/AF(1924-1962): (1)NF-104A
(LR123) (No information)
(LR125) (No information)
(LR127) (No information)
LR129 Pratt & Whitney (engine developed for boost/glide aerospace craft; later modified into unsuccessful competitor for Space Shuttle main engine)
LR132 Rocketdyne RS-47 ("Orbital Transfer Engine")

SR9 Hercules Powder  
SR11 Hercules Powder LGM-30(Retro Motor)
SR13 Lockheed  
SR19 Aerojet (1)LGM-30F/G(2nd stage)
SR45 Atlantic Research (1)PWN-6, (1)PWN-7
SR47 United Technology Center Titan III(Zero Stage)
SR49 Thiokol TU-289 (1)AIR-2
SR51 Thiokol LGM-25C(Retro Motor)
SR55 United Technology Center LGM-25C(Staging Motor)
SR59 Atlantic Research LGM-30(Pitch Motor)
SR61 Atlantic Research LGM-30(Spin Motor)
SR71 Aerodyne (1)PWN-8
SR73 Aerojet/Thiokol (1)LGM-30G(3rd stage)
SR75 Lockheed (1)AGM-69, (1)ASM-135
SR105 Aerojet (1)2.75" Improved FFAR
SR109 Thiokol TX-481 (1)AGM-65
SR110 Aerodyne (1)PWN-10, (1)PWN-11, (1)PWN-12
SR113 Thiokol (1)AGM-88
SR114 Thiokol TX-633 (1)AGM-65
SR115 Aerojet (1)AGM-65
SR116 Aerojet (1)AIM-9J/P
SR118 Thiokol (1)LGM-118(1st stage)
SR119 Aerojet (1)LGM-118(2nd stage)
SR120 Hercules (1)LGM-118(3rd stage)
SR121 Naval Propellant Plant MQM-107(Booster)
SR122 Rocketdyne (also designated WPU-9/B)
(1)AGM-130

6 Sources

In no particular order:

[1] James C. Fahey: "The Ships and Aircraft of the US Fleet", 6th, 7th and 8th ed., U.S. Naval Institute, 1955, 1958, 1965
[2] James C. Fahey: "United States Air Force and United States Army Aircraft 1947-1956"
[3] James C. Fahey: "United States Army Aircraft 1908-1946"
[4] Department of Defense: MIL-STD-1812A "Aeronautical and Support Equipment Type Designation System"
[5] Gordon Swanborough, Peter M. Bowers: "United States Military Aircraft since 1908", Putnam, 1989
[6] Gordon Swanborough, Peter M. Bowers: "United States Naval Aircraft Since 1911", Putnam
[7] Bill Gunston: "World Encyclopedia Of Aero Engines"
[8] John M. Andrade: "U.S. Military Aircraft Designations and Serials 1909-1979", Midland, 1979
[9] Norman J. Bowman: "The Handbook of Rockets and Guided Missiles", Perastadion Press, 1963
[10] USAF Air Materiel Command: "Model Designations of U.S.A.F Aircraft Engines, Revised January 1, 1950"
[11] Air Force-Navy Aeronautical (ANA) Bulletin 306M: "Engines, Aircraft Turbine and Jet, Designation Of"





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Last Updated: 14 February 2024