Jet Engine Types — Family Index

Taxonomy of aircraft and missile propulsion: six gas-turbine families (turbojet, low-bypass turbofan, high-bypass turbofan, geared turbofan, turboprop, turboshaft), three non-rotating-compressor families (ramjet, scramjet, rocket), and the OEM product lines that populate each category in 2026. All gas-turbine variants share the Brayton-cycle topology — inlet, compressor, combustor, turbine, nozzle — and differ in how shaft power is converted to useful thrust or torque (core jet, ducted fan, free propeller, rotor shaft).

1. At a glance

Nine top-level families, distinguished by working-fluid path and energy-extraction method:

Family	Working fluid path	Useful output	Typical M	SFC (lb/lbf·hr)	Era
Turbojet (pure)	All through core	Core jet thrust	0.8–3.0	0.9–1.1	1940–70
Turbofan — LBP (BPR<2)	Core + small bypass	Core+fan jet, AB opt.	0.9–2.5	0.7–0.9 (dry)	1965–
Turbofan — HBP (BPR 5–12)	Large fan duct + core	~80 % fan thrust	0.78–0.92	0.50–0.60	1970–
Geared TurboFan (GTF)	HBP + reduction gearbox 3:1 fan/LPT	Fan thrust	0.78–0.85	0.43–0.50	2016–
UHBR / Open rotor	BPR > 13, possibly unducted	Fan / open-rotor thrust	0.72–0.82	0.40–0.45 target	2030+
Turboprop	Core gas-gen + reduction-gear propeller	Propeller shaft power	0.4–0.7	0.45–0.65	1948–
Turboshaft	Core gas-gen + free power turbine + shaft	Rotor / APU shaft	n/a	0.45–0.60 SFC_sh	1955–
Ramjet	Inlet shock compression, no rotor	Core jet thrust	1.0–4.0	1.5–3.0	1950s–
Scramjet	Supersonic combustion	Core jet thrust	4.0–10+	data-sparse	2004–
Rocket (chemical)	Onboard oxidizer + fuel, no air-breathing	Nozzle exhaust	any	Isp 250–450 s	1942–

Bypass-ratio bands as conventionally used in 2026: low-bypass (BPR < 2, mostly military fighter), high-bypass (BPR 5–12, civil airliner workhorse), ultra-high-bypass / open-rotor (BPR > 13, in development). All air-breathing gas turbines share the same five major stages; the architectural choice is whether to keep working fluid in the core (pure-jet thrust) or expand the turbine further to drive a fan / propeller / rotor (shaft-power extraction).

2. Performance metrics

The figures-of-merit used across the families.

• Thrust-to-weight ratio (TWR) — installed dry thrust over engine dry weight. Civil HBP 5–6:1, military fighter LBP 8–10:1, F119/F135 close to 11:1.
• Specific fuel consumption (SFC, TSFC) — fuel flow per unit thrust, lb/(lbf·hr) or kg/(N·hr). The dominant lifecycle cost driver on civil engines; trend over 60 yr from 1.0 (turbojet) → 0.55 (CFM56) → 0.45 (LEAP/GTF) → 0.40 target (UltraFan/RISE).
• Bypass ratio (BPR) — m_dot_fan / m_dot_core. Higher BPR raises propulsive efficiency at the cost of fan diameter, weight, and nacelle drag.
• Overall pressure ratio (OPR) — total pressure at combustor inlet / freestream stagnation. Civil engines have climbed 25 → 60 over five decades (GE9X is the production leader at OPR 60).
• Turbine entry temperature (TET, T4) — combustor exit stagnation temperature. 1600–1900 K in modern HBP; metal kept at 1100–1300 K via film-cooling + thermal-barrier coating.
• Thrust-specific air consumption (TSAC) — m_dot_total / thrust. Inverse of specific thrust.
• Time-on-wing (TOW) — calendar / cycle interval between heavy shop visits. CFM56 industry-best at 25–30 k cycles; LEAP-1A 2016–2023 entry-into-service had teething TOW issues since corrected.

Other common ratings: specific thrust (N·s/kg), propulsive efficiency η_p = 2/(1 + V_j/V_∞), thermal efficiency η_th, exhaust velocity V_j, jet noise EPNdB (ICAO Chapter 14).

3. Turbojet

The original gas-turbine architecture (von Ohain 1939, Whittle 1941). All air mass flow passes through compressor + combustor + turbine + nozzle, exiting as a single high-velocity core jet. SFC at cruise ~1.0 lb/(lbf·hr) — fuel-hungry compared to bypass engines, but compact and simple. Today no commercial airliner uses a pure turbojet; the architecture survives in supersonic missiles, some training aircraft, and as the conceptual basis of low-BPR military engines.

Historical lineage:

• GE J47 (1948) — B-47 Stratojet, F-86 Sabre. ~35 000 produced, the most-built jet engine in U.S. history.
• GE J79 (1955) — F-104 Starfighter, B-58 Hustler, F-4 Phantom II. 17 820 built.
• P&W J57 (1952) — B-52, F-100 Super Sabre, U-2. Twin-spool design pioneered the split-compressor concept.
• P&W J58 (1962) — SR-71 Blackbird. Bleed-bypass turbojet, M 3.3+ sustained.
• Rolls-Royce Olympus 593 Mk 610 (1976–2003) — Concorde supersonic transport. Reheat (afterburning) twin-spool, ~38 000 lbf with afterburner.

Modern “supersonic military” engines (often called turbojets colloquially) are in fact low-BPR turbofans with afterburner — see §4.

4. Turbofan — low bypass (LBP, BPR < 2)

A small bypass duct surrounds the core; bypass air can be mixed with core exhaust before the nozzle (mixed-flow) or exhaust separately (unmixed). Afterburner injects fuel into the mixed stream for short bursts of supersonic thrust at high SFC penalty. The standard architecture for military fighters since the 1970s.

Engine	Aircraft	Thrust dry / AB (kN)	BPR	OPR	Year
P&W F100-PW-229	F-15, F-16	79 / 129	0.7	32	1974
GE F110-GE-129	F-16, F-15EX	76 / 129	0.8	30.7	1984
GE F404-GE-402	F/A-18 Hornet	49 / 78	0.34	26	1978
GE F414-GE-400	F/A-18 Super Hornet, Gripen E	58 / 98	0.4	30	1998
EJ200 (Eurojet)	Eurofighter Typhoon	60 / 90	0.4	26	2003
P&W F119-PW-100	F-22 Raptor (2-D TVC)	116 / 156	0.3	35	2005
P&W F135-PW-100	F-35 Lightning II	125 / 191	0.57	28	2009
Klimov RD-33	MiG-29	50 / 81	0.49	22	1985
Saturn AL-31F	Su-27, Su-30	75 / 122	0.59	23	1985
AL-41F1 (117S)	Su-35, Su-57	88 / 142	0.59	28	2010

P&W F135 is the single-largest military engine ever certified (191 kN with afterburner); its derivative the F135 EEP (Engine Core Upgrade) is in development for the F-35 Block 4. Specific thrust band 1000–1500 N·s/kg.

5. Turbofan — high bypass (HBP, BPR 5–12)

The civil-airliner workhorse since the JT9D / CF6 / RB211 generation (1970–1972) introduced BPR 4.5–5. Roughly 80 % of useful thrust comes from the fan, not the core, dramatically improving propulsive efficiency at subsonic cruise (M 0.78–0.85). Fan stage dominates engine weight, diameter, and noise.

Single-aisle family:

• CFM56 (1981, BPR 5–6.4) — 737 Classic/NG, A320ceo, KC-135R, DC-8 Super 70. ~35 000 produced; the most successful civil engine ever. -3 / -5 / -5B / -7B variants.
• IAE V2500 (1989, BPR 4.6, OPR 35.4) — A320ceo alternative. P&W + RR + JAEC + MTU consortium. Production ended 2024.
• CFM LEAP-1A / -1B / -1C (2016, BPR 11, OPR 40, 24–35 klbf) — A320neo, 737 MAX, COMAC C919. Composite fan, CMC HPT shroud, TAPS-II combustor.
• P&W PW1100G-JM (2016, BPR 12, OPR 50, 24–33 klbf) — A320neo GTF; see §6.
• P&W PW1500G (2016) — A220.
• P&W PW1900G (2018) — Embraer E2-Jet.

Wide-body family:

• GE CF6 (1971, BPR 4.3–5.1) — 747, A300/A310, 767, MD-11. Production ended 2022.
• P&W JT9D (1970) — 747-100 original. Predecessor of PW4000.
• P&W PW4000 (1987, BPR 4.8–6.4) — 747-400, 767, 777-200/300, MD-11, A300/A310, A330. 94-inch, 100-inch, 112-inch fan variants.
• RR RB211 (1972, BPR 4.4) — L-1011 TriStar, 747-400, 757, 767. Three-spool architecture, RR signature.
• RR Trent 700 / 800 / 900 / 1000 / XWB / 7000 (1995–2018, BPR 5–10) — A330, 777, A380, 787, A350, A330neo. Three-spool.
• GE GE90 (1995, BPR 8.7, OPR 42, 110–115 klbf) — 777-200LR/300ER/F. World’s largest until GE9X.
• GE GEnx-1B / -2B (2008, BPR 9.5, OPR 47) — 787, 747-8.
• GE9X (2020 certification, BPR 9.9, OPR 60, 100–110 klbf) — 777X. World’s largest in service since the 777-9 EIS (delayed to 2025–26). 134-inch fan, 16 4th-generation composite blades.
• EA GP7200 (Engine Alliance — GE + P&W JV, 2008) — A380 alternative to Trent 900.

Cargo / freighter: most variants above plus the dedicated CFM56-2 on DC-8 Super 70 freighters. Specific thrust 250–400 N·s/kg.

6. Geared TurboFan (GTF)

A reduction gearbox (~3:1 ratio) decouples the fan from the low-pressure turbine, letting each spin at its aerodynamic optimum: large slow fan for high BPR + low tip-speed noise, fast small LPT for fewer stages and lower weight. Concept tested in the P&W ADP demonstrator (1991), entered service in 2016 on the PW1500G (A220) and PW1100G (A320neo).

Engine	Application	BPR	OPR	Thrust (klbf)
PW1100G-JM	A320neo	12.5	50	24–33
PW1500G	A220	12	38	21–23
PW1900G	Embraer E190/195-E2	12	38	19–22
PW1200G	MRJ / SpaceJet (cancelled)	9	36	17
PW1700G	E175-E2 (delayed)	11	36	15

Claimed benefit ~15 % SFC improvement over CFM56, ~50 % lower NOx, ~75 % lower noise footprint. Reliability issue: a powdered-metal contamination defect in HPT and HPC disks (Pratt & Whitney supplier issue identified 2023) forced a fleet-wide accelerated inspection program; at peak in 2024 over 200 A320neo airframes were AOG. The defect is contained and the inspection backlog has been working down through 2025–26.

Rolls-Royce UltraFan demonstrator (RB3025 testbed) ran first full power 2023 at the Derby outdoor testbed, achieving BPR 15+ with a 140-inch fan and a 64 OPR core; designed as the platform engine for the Trent successor in the 2030s. Composite fan blades and case, hybrid-electric-ready architecture, 25 % SFC improvement vs first-generation Trent.

7. Ultra-High Bypass Ratio (UHBR / open-rotor)

BPR > 13, often unducted (open-rotor / propfan). The aerodynamic optimum for subsonic cruise efficiency, blocked historically by noise and integration challenges.

• CFM RISE (Revolutionary Innovation for Sustainable Engines) — GE + Safran JV concept, unducted open-rotor with contra-rotating composite fan + variable-pitch blades. Target: 20 % better SFC than LEAP, hydrogen / SAF capable, entry-into-service 2035. Ground tests at GE Peebles 2024+.
• RR UltraFan — ducted UHBR, BPR 15, see §6.
• Boeing X-66 — Transonic Truss-Braced Wing demonstrator with hybrid-electric / UHBR engine integration, first flight slipped to 2028.
• MTU Aero Engines + Pratt & Whitney open-rotor patents (2019–2023) — gearbox heritage applied to a propfan with planetary differential.
• Russian PD-35 — UEC (Aviadvigatel) UHBR-class engine for the CR929 / Il-96-400M, BPR 11–12, certified design point 35 klbf, ground tests 2024.

The unducted open-rotor faces three principal certification hurdles: contained-failure (a blade-out from an unducted rotor can shed downstream into the aircraft), community noise, and the FAA / EASA stance on a propfan-class category that did not exist for civil regulation in 2025.

8. Turboprop

A gas-turbine gas-generator drives a propeller through a reduction gearbox (typically 10:1 to 20:1). Total mass flow through the propeller is one to two orders of magnitude larger than the core flow, giving very high propulsive efficiency at low altitude and low Mach (typically capped at M 0.7 by propeller-tip shock). SFC 0.45–0.65 lb/(lbf·hr equivalent), the lowest of all air-breathing aircraft engines per unit fuel burned at regional ranges.

Major product lines:

• Pratt & Whitney Canada PT6A — the universal small-turboprop. 60+ variants from 580 shp (PT6A-11) to 1825 shp (PT6A-67D). Cessna 208 Caravan, Beechcraft King Air, Pilatus PC-12, Pilatus PC-21, Air Tractor AT-802. > 60 000 produced since 1963.
• P&W Canada PW100 / PW150 — Dash 8-100/200/300 (PW120/123), Dash 8-Q400 (PW150A 5071 shp), ATR 42/72 (PW127). PW150 the second largest civil turboprop in production after the NK-12.
• GE T700 / CT7 turboshaft is also offered as a CT7-9C turboprop on the Saab 340.
• GE Catalyst (formerly Advanced Turboprop ATP) — clean-sheet design 2020, the first all-new civil turboprop in over 50 years. 1240 shp, 16:1 OPR, FADEC, 3D-printed components (one-shot LPBF compressor inlet, turbine center frame). Beechcraft Denali (entry-into-service slipped to 2025–26), Cessna SkyCourier 408 alternative.
• Honeywell TPE331 — Jetstream 31/41, Fairchild Metro, MU-2. 575–1645 shp.
• Rolls-Royce / Allison T56 (1954) — C-130 Hercules, P-3 Orion, E-2 Hawkeye, C-2 Greyhound. 4910 shp (T56-A-15). Multi-billion-hour fleet.
• Europrop TP400-D6 — A400M Atlas. 11 000 shp, the largest Western turboprop in service. Four-engine consortium (RR + Safran + MTU + ITP).
• Klimov / Kuznetsov NK-12 — Tu-95 Bear, An-22 Antei. 14 795 shp, contra-rotating, the largest and most powerful turboprop ever produced. Still in low-rate production for Tu-95MSM upgrades.
• Honeywell HTP800 turboprop variant of HTS900 — military trainers.

Speed-limited to ~M 0.7 by propeller-tip shock and gearbox stress; above that, turbofans dominate.

9. Turboshaft

Gas-turbine gas-generator + free power turbine + output shaft delivering torque, with no significant propulsive jet from the core nozzle. The standard helicopter and APU architecture.

Helicopter turboshaft:

• GE T700 / CT7 — UH-60 Black Hawk, AH-64 Apache, S-70/S-92, NH90, AW101. 1500–2000 shp. Over 23 000 produced.
• GE T408 — Sikorsky CH-53K King Stallion. 7500 shp.
• GE T901 — Improved Turbine Engine Program (ITEP) replacing T700 in UH-60 / AH-64 from 2026; 3000 shp.
• Safran Makila 1A / 2A — Eurocopter Cougar / EC225 Super Puma / H225M Caracal. 1800–2100 shp.
• Safran Arriel — Dauphin AS365, AS350 Ecureuil, S-76C, AW119. 700–1000 shp. The most-produced helicopter engine family in the West.
• Safran Ardiden — Dhruv (HAL), Ka-62. 1400–1800 shp.
• Safran RTM322 / Aneto — NH90, AW101 (RTM322 1700 shp); H160 (Arrano 1100 shp); H175 / Z-15 (Aneto-1K 2500 shp).
• Klimov TV2-117 / TV3-117 / VK-2500 — Mi-8 / Mi-17 / Mi-24, Ka-50/52. 1900–2400 shp.
• Klimov D-136 — Mi-26 (the world’s heaviest helicopter); two engines at 11 400 shp each. The largest single turboshaft ever produced.
• Rolls-Royce M250 / Allison 250 — Bell 206/407, MD500/600, AW119. 420–715 shp. ~31 000 produced.
• Honeywell HTS900 — Bell 407HP retrofit. 970 shp.

Auxiliary power units (APU):

• Honeywell 131-9A / 131-9B — A320 family / 737NG/MAX. The dominant single-aisle APU.
• Honeywell 36-150 — regional and biz-jet.
• P&W Canada APS3200 — A320ceo legacy.
• P&W Canada APS5000 — 787.
• Honeywell HGT1700 — A350.
• Safran ePower / e-APU — fully-electric APU competing with conventional gas-turbine APU on next-gen single-aisle and regional.
• GE GTCP85 — older transport (DC-8, 727, classic 737).

Industrial / marine derivatives (e.g., LM2500 from CF6, MT30 from Trent 800) cross into the gas-turbine-power discipline → [[Engineering/gas-turbines]].

10. Components common to all gas-turbine families

The five-stage architecture (inlet → compressor → combustor → turbine → nozzle) is shared. Material and aerodynamic choices vary by family.

Inlet / fan

• Civil HBP fan: titanium hollow-blade (P&W blisk wide-chord, RR swept hollow); modern GE9X uses 16 composite (carbon-fiber polymer) fan blades with titanium leading-edge sheath for bird strike. LEAP-1A uses 18 woven 3-D RTM composite fan blades.
• Nacelle: composite outer barrel, aluminum or composite inner barrel, acoustic-treated inlet lip.
• Cross-ref: [[Engineering/Tier3/titanium-alloys]], [[Engineering/Tier3/composites-taxonomy]].

Compressor

• Axial multi-stage, 10–25 stages typical. Civil HBP: 1 fan + 3–5 booster (LPC) + 9–11 HPC stages.
• Blisks (bladed disks, integrated forging) replace bolted assemblies in mid-life upgrades; MTU pioneered for both Ti (front stages) and Ni (rear stages).
• Last-stage compressor materials follow temperature: Ti-6Al-4V → Ti-6242 → Ti-1100 → Ni Inco 718 → Ni 939 / Astroloy in the hottest HPC stations.
• Variable-stator vanes (VSV) and inter-stage bleed for surge protection at part-power.

Combustor

• Legacy: Rich-burn Quick-quench Lean-burn (RQL); annular geometry. CFM56, V2500, JT8D.
• Modern lean-direct-injection (LDI) / lean-burn for low NOx: CFM TAPS-II (LEAP), GE TAPS-III (GE9X), P&W TALON-X (PW1100G), RR ALECSys (Trent XWB-97 / UltraFan).
• Liner materials moving from cast Hastelloy / Haynes 188 to SiC/SiC ceramic-matrix composite (CMC): GE9X CMC HPT shroud and aft combustor liner have been in commercial service since 2016 (on GEnx-1B with PIP-2 retrofit).
• Cross-ref: [[Engineering/Tier3/composites-taxonomy]] (CMC subsection).

HPT (high-pressure turbine)

• Blade material: nickel single-crystal (SX) superalloy — René N5, CMSX-4, CMSX-10, TMS-238 (NIMS Japan, ATSR-class), in roughly that vintage order.
• Cooling: film cooling via EDM- and laser-drilled holes; serpentine internal passages with turbulators; thermal-barrier coating (TBC) yttria-stabilized zirconia (YSZ) sprayed by APS or EB-PVD.
• TET (T4) reaches 1600–1900 K with the metal kept at 1200–1300 K by the film + TBC margin.
• Cross-ref: [[Engineering/Tier3/welding-processes]] (EDM, laser drilling), [[Engineering/Tier3/surface-treatments]] (thermal-spray TBC).

LPT (low-pressure turbine)

• Multistage (3–7 stages), Ni alloy (Inco 718, Waspaloy, René 80). Increasingly blisked in newer designs.
• Drives the fan directly (conventional turbofan) or through the reduction gearbox (GTF).

Nozzle

• Convergent fixed nozzle on subsonic civil; convergent-divergent variable on supersonic military.
• Reheat / afterburner section: fuel-spray manifolds in the jetpipe, variable-geometry nozzle (F100, F119, AL-31). 2-D vectoring nozzle on F-22 (pitch only); 3-D nozzle on Su-35/Su-57 (multi-axis).

11. Performance numbers (latest production examples)

CFM LEAP-1A — Airbus A320neo

• BPR 11, OPR 40, fan diameter 198 cm (78 in), 18 woven 3-D composite fan blades.
• Thrust class: 24 500–35 000 lbf.
• SFC 12–15 % better than CFM56-7B at cruise.
• CMC HPT stage-1 shroud — first commercial CMC turbine hot-section part in production.
• 3-D printed cobalt-chrome fuel nozzle tip (single piece replacing 20-part assembly) since 2015.

GE9X — Boeing 777X

• BPR 9.9, OPR 60 (highest production OPR), 11-stage HPC, 6-stage LPT.
• Fan 134 in (3.4 m) — largest turbofan fan ever fielded.
• 16 fourth-generation composite fan blades + titanium leading edge.
• SiC/SiC CMC HPT stage-1 and stage-2 shrouds, stage-1 nozzle, combustor inner and outer liner.
• 3-D printed (LPBF) fuel nozzles in serial production; T25 sensor housing also additively made.
• Certified 2020; entry-into-service with 777-9 slipped from 2020 → 2026.
• Thrust class: 100 000–110 000 lbf.

P&W PW1100G-JM — Airbus A320neo GTF

• BPR 12.5, OPR 50, fan 81 in, gear ratio 3.062:1.
• Thrust class: 24 000–33 000 lbf.
• TALON-X combustor for low NOx.

RR Trent XWB-84 / XWB-97 — Airbus A350

• Three-spool, BPR 9.6, OPR 50.
• Thrust class: 84 200 lbf (-84) / 97 000 lbf (-97).
• Composite fan track liner; advanced IP / HP turbine cooling.
• The first Trent variant to incorporate the ALECSys lean-burn combustor (XWB-97).

RR UltraFan demonstrator

• BPR 15+, OPR 64, gear-driven, 140-in composite fan. First full-power run 2023.

12. Ramjet / scramjet

Air-breathing engines without rotating compressors; useful thrust requires the vehicle to be already supersonic so that inlet shock-compression substitutes for the missing turbomachinery.

Ramjet — subsonic combustion in a converging-diverging duct. Operates M 1.0–4.0.

• Marquardt RJ43 — Bomarc, Lockheed D-21 drone.
• Pratt & Whitney RJ57 — Bomarc-A.
• Aerojet / Sea Dart — research.
• Nike-Talos RJ43.
• MBDA Meteor — air-to-air, throttleable solid-fuel ducted-rocket / ramjet hybrid.
• MBDA / EADS ASMP-A — French nuclear stand-off missile, kerosene ramjet.

Scramjet — supersonic combustion. Operates M 4–10+.

• NASA X-43A (2004) — Mach 9.6 on hydrogen, 10 s burn. World record at the time.
• Boeing X-51 Waverider (2010–2013) — Mach 5.1 sustained for 4 minutes on JP-7 hydrocarbon fuel.
• DARPA HyFly — early 2000s hydrocarbon-scramjet missile demonstrator.
• Russian 3M22 Zircon (operational 2022+) — anti-ship cruise missile, Mach 9 claimed, kerosene scramjet.
• India BrahMos-II — Indo-Russian scramjet, in development.
• China DF-ZF / WU-14 — boost-glide hypersonic vehicle (some sources classify as scramjet-powered final stage).

Combined-cycle research: turbine-based combined cycle (TBCC, turbojet-to-ramjet handover) for Mach 0-to-5 air-breathing flight, e.g., Reaction Engines SABRE (UK, hydrogen pre-cooled), demonstrated heat-exchanger 2019. Cross-ref: [[Engineering/hypersonics]].

13. Rocket engines (chemical)

No air-breathing; on-board oxidizer + fuel. The only family that operates outside the atmosphere.

Solid — propellant cast into the case; thrust governed by burn-surface geometry.

• NASA Space Shuttle SRB; SLS five-segment SRB; Atlas V GEM-63 strap-on; Ariane 5 EAP, Ariane 6 P120C; Vega P80; H-IIA SRB-A.
• Military: Minuteman III, Trident D5, Peacekeeper, M51 (France), DF-31/41 (China).
• Isp 250–265 s.

Liquid kerolox (RP-1 / LOX)

• F-1 Saturn V first stage, 1.5 Mlbf SL each, 5 engines per booster. Retired.
• SpaceX Merlin 1D (190 klbf vac), 9 + 1 per Falcon 9.
• Russian RD-180 (860 klbf SL, Atlas V); RD-191 (190 klbf, Angara); NK-33 (340 klbf, vintage N1).
• China YF-100 (1200 kN, Long March 5/6/7); YF-130 (4800 kN, 2025+ Long March 9).
• Isp 265–330 s.

Liquid hydrolox (LH2 / LOX) — highest Isp chemical.

• Aerojet Rocketdyne RS-25 (Shuttle/SLS, 418 s vac, 232 klbf), RL-10 (Centaur upper stage, 465 s vac).
• ArianeGroup Vulcain 2 / Vulcain 2.1 (Ariane 5/6); HM7B → Vinci upper-stage Ariane 6.
• Blue Origin BE-3U upper stage (New Glenn).
• JAXA LE-7A, LE-9 (H3); RD-0120 (Energia heritage).
• Isp 350–450 s; high specific impulse, large tank volume.

Liquid methalox (CH4 / LOX) — emerging family targeting reusability.

• SpaceX Raptor 1 → Raptor 2 → Raptor 3 (Starship Super Heavy, 280–330 tf each at sea level), Isp ~350 s SL / ~378 s vac.
• Blue Origin BE-4 (550 klbf SL, New Glenn first stage and ULA Vulcan first stage).
• ULA Vulcan Centaur entered service 2024 with twin BE-4.
• Rocket Lab Archimedes (Neutron 2026+); Relativity Aeon-R; ESA Prometheus demonstrator; UEC RD-0177; China YF-215 (Long March 9 future).

Hypergolic (spontaneous ignition: UDMH/NTO, MMH/NTO).

• Soviet RD-275M Proton-M; Aerojet AJ10 (Delta II second stage, Orion service module); Apollo SPS heritage; Chinese YF-21/22.
• Storable, simple ignition; toxic.

Hybrid (solid fuel + liquid oxidizer).

• Virgin Galactic SpaceShipTwo — HTPB / N2O.
• Gilmour Space Eris (Australia, 2024+); Korea Innospace HANBIT-Nano.

Non-chemical / electric propulsion (cross-reference for completeness — orbital application).

• Hall-effect thrusters: SPT-100 (1500 s Isp), Aerojet XR-5, NASA AEPS for Lunar Gateway.
• Gridded-ion: NSTAR (3100 s, Dawn), NEXT (4170 s, Psyche 2023).
• VASIMR (Ad Astra, plasma magnetic), in development.
• Nuclear thermal NTP — NERVA legacy 1960s; DARPA DRACO + NASA in-orbit demo NET 2027.
• Nuclear-electric NEP — concept studies for crewed Mars.

→ [[Engineering/Tier3/electric-motor-taxonomy]] for the magnetic-drive analogs of plasma propulsion.

14. OEM consolidation map (2026)

Civil large turbofan — three primary OEMs and one major JV.

• CFM International (GE Aerospace + Safran Aircraft Engines 50/50 JV, exclusive 737 / 737 MAX engine, A320ceo / A320neo co-supplier).
• Pratt & Whitney (RTX subsidiary post-2023 Raytheon-Technologies rebrand). PW1000G GTF family, plus legacy PW4000 / JT9D.
• Rolls-Royce Civil — Trent family monopoly on the A350 (XWB-84 / XWB-97), shared on A330neo (Trent 7000 exclusive), 787 (Trent 1000 alongside GE GEnx), legacy A380 (Trent 900).
• Engine Alliance (GE + P&W JV) — A380 GP7200 only, production ended with the A380 program in 2021.
• IAE V2500 (P&W + RR + JAEC + MTU) — A320ceo, production ended 2024, support ongoing.

Wide-body — GE Aerospace (independent OEM since the 2024 GE corporate split), RR, P&W.

Military combat — P&W (F100, F119, F135), GE Aerospace (F110, F404, F414, F101, NGAP for NGAD), RR Defense (EJ200 50 %, AE 3007, AE 2100), Safran (M88 Rafale, M53 Mirage 2000), Eurojet Turbo (4-way consortium RR + MTU + Avio + ITP for EJ200), Klimov + UEC Saturn (Russia, AL-31F / 41F1 / Izdeliye 30 for Su-57), AVIC + AECC (China, WS-10 Taihang, WS-15 for J-20, WS-20 for Y-20, WS-21, WS-22).

Turboprop — P&W Canada (RTX, PT6A + PW100/150 dominant), GE Aviation (Catalyst, T56/T408 mil), Honeywell (TPE331), Klimov / Aviadvigatel (TV7-117), Europrop consortium (TP400-D6).

Turboshaft — Safran Helicopter Engines (formerly Turbomeca, market share leader), GE Aviation (T700/CT7, T408, T901 ITEP), P&W Canada, RR (M250 + Helicopter business), Klimov (VK-2500), Honeywell.

APU — Honeywell, P&W Canada, Safran Power Units (ePower / e-APU), historical GE GTCP.

Rocket propulsion — SpaceX (Merlin, Raptor), Blue Origin (BE-3, BE-4, BE-7), Northrop Grumman (Antares engines, GEM SRBs, Castor), Aerojet Rocketdyne (now an L3Harris subsidiary since 2023; RS-25, RL-10, AJ10), United Launch Alliance Vulcan (BE-4 + RL-10 + GEM-63XL), Avio (Vega, Ariane SRBs), ArianeGroup (Vulcain, Vinci), JAXA / MHI (LE-9), CASC (YF-100/115), ISRO (CE-20, CE-25, SCE-200 in development).

15. Certification + standards

• FAR Part 33 (FAA) / EASA CS-E — airworthiness standards for aircraft engines. Bird strike, blade-out containment, ingestion (FOD, ice, hail), endurance, vibration, overspeed, overtemperature, fuel-and-oil system, mounting, lightning.
• FAR Part 25 Appendix B — icing certification envelope.
• FAR Part 23, 25, 27, 29 — aircraft-level rules referencing engine certification.
• ETOPS / EDTO — Extended-range Twin-engine OPerationS, since 1985. 180-min single-engine cruise was the original ceiling (PW4000, Trent 700); 207, 240, 330 min have followed; 370 min for newest 777-200LR.
• ICAO Annex 16 Vol I — aircraft noise; Chapter 14 the current production standard (effective 2018).
• ICAO Annex 16 Vol II — engine emissions: NOx, CO, smoke, UHC, and CO₂ standard adopted 2017 (effective 2020 for new types).
• CAEP (Committee on Aviation Environmental Protection) — ICAO panel that recommends Annex 16 amendments.
• Type Certificate Data Sheets — FAA TCDS E-series and EASA TCDS E.xxx publish the certified envelope (thrust ratings, fuel grades, temperature limits, life-limited parts) of every certified engine.

16. Selection heuristics

• Subsonic narrow-body airliner (150–250 seats, 3000 nmi) — HBP or GTF turbofan, BPR 11–13. Pick on commercial terms: CFM LEAP-1A vs P&W PW1100G on A320neo (operator splits roughly 60/40); CFM LEAP-1B sole-source on 737 MAX. Maintenance reserve, time-on-wing guarantees, power-by-the-hour rates often determine selection.
• Wide-body airliner (250–450 seats, 5000–9000 nmi) — twin: GE9X (777X), GEnx-1B (787-9/-10), Trent 1000 / TEN (787), Trent XWB (A350). Quad legacy: PW4000 / CF6 / RB211 retired or aging.
• Regional turboprop short-field (50–80 seats, < 600 nmi) — P&W Canada PW150A (Q400), PW127 (ATR 72-600).
• Single-engine turboprop biz / utility — PT6A-67D (PC-12), PT6A-114A (Caravan), Catalyst (Denali). Pick on fuel burn vs hot-section overhaul interval.
• Combat fighter — low-BPR turbofan with afterburner; F119 (F-22, with 2-D thrust vectoring), F135 (F-35, single-largest mil engine), F414 (Super Hornet, Gripen E), EJ200 (Typhoon), Izdeliye 30 (Su-57).
• Air-launched cruise missile — small turbofan (Williams F107 in Tomahawk, CFM Microturbo TR60 in Storm Shadow / SCALP), or a small turbojet (J402 in Harpoon).
• Hypersonic vehicle prototype — scramjet (X-43, X-51, Zircon) or rocket-boost-glide (Avangard, DF-ZF). Rocket boost to ignition Mach is universal.
• Spacecraft launch — first stage — kerolox (Merlin, RD-180) or methalox (Raptor, BE-4) for reusable; solid SRBs as strap-ons or on military launchers.
• Spacecraft launch — upper stage — hydrolox (RL-10, Vinci, BE-3U, LE-5B) or methalox (Raptor vacuum) for high Isp.
• Helicopter — turboshaft sized to required power: Bell 407 → M250 / HTS900; UH-60 / AH-64 → T700 → T901 ITEP from 2026; CH-53K → T408 (7500 shp); Mi-26 → D-136 (11 400 shp twin); H225M → Makila 2A.
• APU — Honeywell 131-9 standard for single-aisle (737 MAX, A320 family), 36-150 for regional, HGT1700 for A350. Watch the electric e-APU pivot from Safran on the next-gen single-aisle.

17. Cross-references

• [[Engineering/propulsion]] — first-principles thrust-equation parent note.
• [[Engineering/aerodynamics]] — inlet, fan, nozzle aerodynamics.
• [[Engineering/gas-turbines]] — industrial / marine derivatives of aircraft engines.
• [[Engineering/hypersonics]] — scramjet, combined-cycle, Mach 5+ vehicles.
• [[Engineering/orbital-mechanics]] — context for rocket Isp / Δv budgets.
• [[Engineering/Tier3/composites-taxonomy]] — fan-blade CFRP and CMC hot-section parts.
• [[Engineering/Tier3/titanium-alloys]] — fan, LPC disks and blades.
• [[Engineering/Tier3/welding-processes]] — EBW, LBW, diffusion bonding, EDM-drilling.
• [[Engineering/Tier3/casting-processes]] — investment-cast single-crystal turbine blades.
• [[Engineering/Tier3/additive-manufacturing-taxonomy]] — LPBF fuel nozzles, GE Catalyst printed components.
• [[Engineering/Tier3/surface-treatments]] — thermal-spray TBC, shot-peening.
• [[Engineering/Tier3/electric-motor-taxonomy]] — electric APU, hybrid-electric propulsion.

18. Citations

• FAA, Federal Aviation Regulations Part 33: Airworthiness Standards — Aircraft Engines.
• EASA, Certification Specifications CS-E.
• ETOPS / EDTO rules: FAA AC 120-42B, EASA AMC 20-6.
• Mattingly, J. D., Elements of Gas Turbine Propulsion, 2nd ed., AIAA, 2005.
• Saravanamuttoo, H., Rogers, G., Cohen, H., Straznicky, P., Gas Turbine Theory, 7th ed., Pearson, 2017.
• Boyce, M. P., Gas Turbine Engineering Handbook, 4th ed., Butterworth-Heinemann, 2012.
• Sutton, G. P., Biblarz, O., Rocket Propulsion Elements, 9th ed., Wiley, 2017.
• Hill, P., Peterson, C., Mechanics and Thermodynamics of Propulsion, 2nd ed., Addison-Wesley, 1992.
• FAA Type Certificate Data Sheets, E-series (engine), TCDS-E for each production type.
• EASA Type Certificate Data Sheets, E.xxx series.
• ICAO Annex 16 Vol I (Noise) and Vol II (Engine Emissions), with CAEP/12 amendments.
• OEM technical brochures: CFM LEAP, GE9X, GEnx, P&W PW1000G family, RR Trent XWB / UltraFan, Safran Helicopter Engines product range.