Engine developments
Clean sheet designs and improved programs ready to enter service.
By Owen Davies
Contributing Writer
When revisiting the aircraft propulsion topic for Pro Pilot, I thought of Heraclitus’ famous aphorism, “No man ever steps in the same river twice, for it is not the same river, and he is not the same man.” After reviewing current aircraft engine developments, my corollary to that quotation is, “No reporter ever takes the same snapshot of engine makers, technologies, and markets twice.” Much like flowing waters, they change the moment we look away from them.
For this update, we have a book’s-worth of new engines and research and development (R&D). There is so much to cover that the following highlights may read like bullet points.
CFM International
With more powerplants in the air than any other jet engine maker, this 50/50 collaboration between GE Aerospace and Safran handily outsells its parent companies – and everyone else.
In August 2024, CFM received EASA certification for 4 new LEAP-1A variants for the new Airbus A321XLR. The new models offer 40% more takeoff power than engines now pushing the aircraft and 5% more continuous power. They can be retrofitted to all models in the A320neo family.
The Revolutionary Innovation for Sustainable Engines (RISE) open-fan engine program is making steady progress. In one major change, CFM has replaced the engine’s fixed, variable-pitch blades behind the fan with an unshrouded counter-rotating fan. The company estimates that running the modified RISE engine on sustainable aviation fuel (SAF) will cut net carbon emissions by as much as 80%. Ground testing of the engine is set to begin this year, with flight tests on a modified A380 scheduled for 2026.
In 2022, Airbus partnered with CFM to develop a hydrogen-fueled airliner. That’s off, at least for now. Citing the slow development of hydrogen production and infrastructure, Airbus is focusing on SAF and planning tests on an open-fan – read RISE – engine.
GE Aerospace
This is a busy time for GE, too. The company has begun shipping Passport engines for Bombardier’s Global 8000, which remains scheduled for introduction in the second half of this year. The engine is mechanically identical to that in the Global 7500, but the full authority digital engine control (FADEC) programming has changed.
GE’s Catalyst turboprop finally received FAA certification this February. The clean-sheet design engine is said to offer 10% higher cruise power and 18% lower fuel consumption than competitors. Approval is good news for Beechcraft. Its Denali single has been on hold since 2019, waiting for the Catalyst to become available.
GE has received the go-ahead to build and test a full-scale XA102 adaptive cycle engine. It will be 1 of 5 competitors designed for the Boeing F-47 Next Generation Air Dominance (NGAD) fighter.
The company has been collaborating with NASA on testing a combustor, compressor, and high-pressure turbine intended for the CFM RISE engine.
GE has also been mating a generator to one of its Passport 20 engines. The turbogenerator is part of NASA’s Hybrid Thermally Efficient Core (HyTEC) project. This is one of many hybrid-electric projects GE is working on.
The others are include a 1.2-MW-class turbogenerator for Sikorsky’s tiltrotor HEX vertical takeoff and landing (VTOL) demonstrator, scheduled to begin ground runs later this year, and a MW-class turbogenerators for the Army’s Applied Research Collaborative Systematic Turboshaft Electrification Project (ARC-STEP), for ground and flight tests of a NASA/Boeing converted regional airliner before 2030, and for the Speed and Runway Independent Technologies (SPRINT) VTOL X-plane sponsored by DARPA and the US Special Operations Command. The goal is a scalable VTOL vehicle with cruise speed of 400 to 450 kts.
Rolls-Royce
The big stories at Rolls-Royce are familiar – the Pearl X10 and Ultrafan engines. The Pearl X10, bespoke for the Dassault Falcon 10X, completed 6 months of flight testing last October. Built around the Advance2 engine core, the powerplant is expected to produce less noise and 5% better efficiency than the R-R BR700-series bizjet engines.
R-R has also suggested Pearl engines for the 6th-generation fighter planned as part of the Future Combat Air System being developed by Dassault, Airbus, and Spain’s Indra Sistemas. A demonstrator is tentatively expected to fly in 2027.
That brings us to the 85,000-lb-thrust UltraFan. R-R had put its test program on hold, waiting for a market to appear for the engine. Then the company announced a new round of testing in Jul 2024.
The market they see may not be for the UltraFan itself. Squeezing down the UltraFan to fit the lucrative narrowbody market is an obvious opportunity. R-R committed £3 billion (approx $3.9 billion) to the program and is seeking a subsidy from the British government. The company claims the narrowbody engine could support 40,000 jobs and contribute £120 billion to the UK’s economy.
When it comes to alternative power systems, the company’s big news came in Nov 2024, when it confirmed that it was closing down its electric propulsion unit. However, this does not mean it is out of alternative power systems.
In Jul 2024, R-R began construction of a test stand at NASA’s Stennis Space Center, in Mississippi. The company plans to run full-scale turbines on hydrogen. First up is a modified Pearl 15 turbofan. The combustor was demonstrated late last year. The engine itself is expected to be running on hydrogen this year.
Honeywell
For one of the industry’s premier manufacturers, Honeywell offers remarkably little to be said. When it comes to engine R&D, the company keeps its cards close to its vest.
Honeywell is working on a next generation of its HTF7000-series engines. We know this because it settled a long-running lawsuit from Bombardier early in 2024. As part of the deal, Bombardier agreed to use that next generation of the HTF7000 in a Challenger replacement that has still not been announced.
Also early last year, Honeywell introduced a smaller, lighter-weight APU prototype for business jets and future hybrid-electric aircraft. This would not be of interest here, but the unit will probably be adapted for onboard power generation and distributed propulsion in hybrid-electric aircraft.
The company is also working on a 1-MW-class hydrogen fuel cell for future aircraft. The status of that project has not been announced.
Pratt & Whitney
In Dec 2024, P&W received 2 pieces of good news. First, the GTF Advantage received FAA type certification for the Airbus A320neo family. Deliveries are expected later this year for the A321XLR long-range narrowbody.
And second, the European Union Aviation Safety Agency (EASA) issued type certification for the PW545D, already approved by FAA and Transport Canada. It powers the Cessna Citation Ascend, which is expected to receive type certification and enter service this year.
Late in 2024, P&W received a contract worth up to $1.3 billion to continue work on its F135 engine core upgrade for the Lockheed Martin F-35 Lightning II.
Like GE’s XA102, P&W’s XA103 Next Generation Adaptive Propulsion (NGAP) system has passed the Air Force’s Detailed Design Review. The engines can reconfigure themselves in mid-flight to cut fuel consumption by 25% or deliver 20% more thrust, as needed. One of them will power the Boeing F-47 NGAD fighter.
P&W set to run a PW127XT regional turboprop engine on hydrogen. The test program is supported by the Department of Energy and Canada’s Hydrogen Advanced Design Engine Study (HyADES) program.
The company’s Hydrogen, Steam Injected, Intercooled Turbine Engine (HySIITE) burns liquid hydrogen. Injecting steam into the combustion chamber improves engine efficiency by 35% and cuts nitrogen oxide emissions by a spectacular 99.3%. Company execs believe it will be 2050 before the hydrogen infrastructure exists to make it viable.
The company has also been testing its rotating detonation engine (RDE) for hypersonic aircraft. Unlike a conventional engine, it has an annular combustion chamber. Ignite the fuel, and a detonation wave spins around the ring until you shut it off. With no moving parts, the RDE extracts 25% more energy from the fuel than other powerplants. It can be scaled for anything, from a hypersonic air-to-air missile to a Mach-capable multi-passenger carrier.
In Jul 2024, P&W completed validation tests of its hybrid-electric Scalable Turboelectric Powertrain Technology (STEP-Tech) turbogenerator demonstrator. STEP-Tech is planned for future hybrid powertrains in the 135 to 670-hp range, but it can be scaled up to the 1-MW (1340-hp) class.
Safran
Much of Safran’s R&D these days supports CFM’s RISE program. But not quite all of it.
Early in 2024, Safran and TurboTech, its partner in the BeautHyFuel project, test ran a TP-R90 turbine on hydrogen. The project seeks to develop a hydrogen-fueled turbine for aircraft with 2 to 7 seats.
Around the same time, Safran partnered with ONERA, the French national aerospace research agency, to continue trials with the Ecoengine, a 1/5-scale demonstrator of the RISE engine. So far, tests at the ONERA wind tunnel have proved the fan module and blades, and studied the engine mounted on a wing section. The partnership continues until 2028.
The High Pressure Turbine (HPT) blades tested for the RISE engine are among Safran’s contributions. Made of ceramic matrix composites, they are 1/3 the weight of steel and can work in temperatures up to 2400° F. This helps the RISE engine deliver 20% better fuel efficiency than competing models.
Safran’s HPT blades for the LEAP-1A engine in the Airbus A320neo family received certification in December. Blades for the LEAP-1B engine used on the Boeing 737 Max are expected to receive certification this year. The blades are expected to double the LEAP-1B’s time on wing and cure the engine’s erosion problem in desert environments.
Safran Helicopter Engines, in contrast, is developing its own new and improved products. One of them is the 950-shp Arriel 2W, the newest variant of the Arriel turboshaft family. It will power the upcoming Robinson R88 helicopter, capable of carrying up to 10 pax. The R88 is not expected to receive FAA certification for 3 more years, but Robinson dealers are already taking deposits for the $3.3-million aircraft.
There’s also a 4000-shp-class turboshaft called the Aravalli. It will power India’s new 13-ton-class multi-role IMRH/DBMTH military/naval helicopter. The engines will be built in India.
In mid-2024, Safran Helicopter Engines and MTU Aero Engines formed a 50/50 joint venture called EURA (from EUropean Military Rotorcraft Engine Alliance) to develop a clean-sheet turboshaft engine for heavy helicopters. Delivering 4000–6000 shp, the engines are expected to enter testing in the 2030s, with service to follow by 2040.
Electric power
The ENGINeUS 100 134-hp engine from Safran Electrical & Power received EASA certification this February, following certification by FAA and Transport Canada in mid-2024. In 2026, 4 semi-automated production lines in France and the UK should begin turning out up to 1000 engines per year.
Everett WA-based magniX is developing a new family of HeliStorm electric helicopter engines with rotor speeds of 6000–7000 rpm. The first test engine is expected to deliver about 443 hp and weigh only 165 lb. Production models will be in the 470 to 870 hp range. magniX expects to deliver the first engines to customers in 2026.
One of the most interesting developments comes from NASA’s Glenn Research Center. The 1.4-MW (1877-hp) High Efficiency Megawatt Motor (HEMM) is expected to deliver 19.7 hp/lb at 99% energy efficiency, reducing fuel burn by 3%. Its superconducting rotor coils are chilled to a frosty –370° F and housed in a vacuum chamber to minimize heat transfer with the stator. All this fits into a 16- x 42-inch package. No target date for a complete motor has been announced.
Williams International
In the past year, all the news at Williams has come from its military products. In Dec 2024, the US Department of Defense awarded the company a $253.7 million contract to expand production of the tiny F107-WR-105 turbofans used in the Harpoon and Tomahawk cruise missiles, the Joint Air-to-Surface Standoff Missile, the Long-Range Anti-Ship Missile, and other precision strike weapons and unmanned systems. This likely includes the AGM-86 Air-Launched Cruise Missile , which is also powered by the F107. The engine is only 2 ft long and 12 inches in diameter, weighing in at only 67 lb. Yet, recent models produce up to 700 lb-ft of thrust.
Williams has become a key provider of engines for unmanned weapons systems. The AGM-129A Advanced Cruise Missile is powered by the F112, and at least 3 of the “wingman” drones being developed by the Air Force’s Collaborative Combat Aircraft Program use the larger FJ33 or FJ44 turbofans.
The new manufacturing facility will be located on the company’s campus in Pontiac MI. Contracts under the Defense Production Act often target opening a new facility 18 to 24 months after the grant is awarded, so it will be running late next year or early in 2027.
Owen Davies is a veteran freelance writer specializing in technology. He has been a futurist at Forecasting International and TechCast Global.