Will the Airbus-CFM H2 flight demonstrator use metal or composite fuel tanks?

The Airbus A380 test bed will fly in 2026 with four 100kg tanks of liquid hydrogen – metal and composite materials are being developed through the Airbus ZEROe development center – and there are multiple other plans for development for civil aviation of composite hydrogen tanks, the projects will start in 2021. #Hydrogen
On February 22, Airbus (Toulouse, France) held a press conference announcing a partnership with CFM International (Cincinnati, Ohio, USA) to develop and test a hydrogen internal combustion engine. The plan is to begin flight testing with the Airbus A380 aircraft by 2026 in support of the goal of Airbus Zero Emissions (ZEROe) aircraft entering service by 2035.
As explained by Airbus Chief Technology Officer (CTO) Sabine Klauke, the demo aircraft was the MSN001, the first A380 ever built for certification and later as a trial to certify the Rolls-Royce (London, UK) Trent an A350′s XWB engine. The four-engine A380 testbed will now be modified on a structural stub on top of the fuselage behind the wings. The stub will support the GE (Cincinnati, OH, USA) Passport engine, which is modified to directly burn hydrogen (H2) as fuel.
The engine will be fueled by four cryogenic tanks, each holding 100kg of liquid hydrogen (LH2) at -253°C.The tanks are being developed by ZEROe Development Centers (ZEDC) – located in Bremen (Germany), Nantes (France) and Madrid (Spain) – which opened last year. Both the hydrogen-fueled Passport engine and the LH2 tank will be equipped with sensors to capture extensive data, and the tank will be housed in a sealed container.
Mohamed Ali, vice president of engineering at GE Aviation, explained that the Passport test engine program will implement a low-temperature fuel delivery system that converts LH2 into a gas that is then mixed with air and injected into the engine. Not only is this mixture completely gaseous—compared to the liquid jet fuel/air mixture fed into conventional engines today—but the hydrogen burns at higher temperatures, 10 times faster than jet fuel. Technology to control and stabilize flames needs to be developed, but CFM has a long history in advanced materials that can help address these new requirements, Ali said.
GE’s Passport engine uses the Ox/Ox CMC in the core shroud, mixer (shown) and center body. Image credit: GE Aviation, “Ceramic Matrix Composites: A Heat Engine Solution”
Advanced materials for CFM include high temperature metal alloys and coatings and ceramic matrix composites (CMC) in the engine hot section, as well as carbon fiber reinforced polymer (CFRP) structures such as fan cases, vanes and fan blades in the front “cold section”” engine section. In the Passport engine, alumina fiber reinforced alumina (Ox/Ox) CMC is used for the corrugated annular exhaust mixer as well as the center body and core cover. 20 kg saved in the mixer alone, CMC Allows higher temperature combustion, requires no additional coatings or insulation, and is lighter than metal.
Composite fairing door (top) and inner barrel (bottom) for the Nexcelle integrated propulsion system nacelle for a GE Passport engine. Image credit: Nexcelle
As part of the Integrated Propulsion System (IPS) supplied by Nexcelle (Baltimore, MD, USA), the Passport engine contains more composite material in the nacelle – a joint venture between Safran Nacelles (Paris) and ST Engineering (Singapore) 50/50 joint venture Baltimore-based Mid-River Aircraft Systems. The IPS includes a 360-degree one-piece composite inner barrel with advanced acoustic protection to reduce engine noise, a clamshell composite fan shroud for better maintenance and a composite thrust reverser (manufactured by Safran Nacelles), according to report the use of thermoplastic materials. Composites feature prominently in the Safran nacelle video below.
Asked by industry media if the fuel tanks would be made of composites, Kroker replied that Airbus is working on metals and composites through its Zero Electronics Development Center (ZEDC). Announcing ZEDC in Madrid last December, Airbus noted: “Airbus has long been a pioneer in composites technology in Spain, both in terms of materials and manufacturing processes. The focus of ZEDC in Spain is on non-propulsion energy, fuel cell cooling and fiber optic systems, as well as carbon fiber tanks for the storage of cryogenic liquid hydrogen. Tank development is being done in a coordinated manner with other Airbus national entities. These technologies are critical to fueling future zero-emission aircraft, supporting by 2035 put into use.”
One of the processes pioneered by Airbus in Spain is the use of automated fiber placement (AFP) for in-situ consolidation of thermoplastic composites (ISC TPC) without the need for an autoclave. By 2016, the Spanish composites research and development center FIDAMC (Getafe, on the outskirts of Madrid, Spain) demonstrated ISC TPC skin stringer panels as part of the ISINTHER project (see “Thermoplastic composite wing on the horizon”).This technology has been further matured in Clean Sky projects ICARO, TARGET, ECO-DESIGN and Green Regional Aircraft-Light (GRA-LW), allowing it to be included in the Clean Sky 2 FTB#2 flight demonstrator (see “IIAMS Wing Box” Type Certification Roadmap”), with first flight in February 2022.
Notably, several initiatives have been announced recently that include research into the use of thermoset and thermoplastic composites in hydrogen storage tanks, including:
Why use an A380 and Passport engine? Klauke noted that the A380 provides ample space to install all the necessary equipment within the aircraft, including the LH2 fuel tank and its containment, fuel delivery and test bed monitoring systems, as well as a test monitoring station. IN addition, the aircraft has four powered engines, providing space and the ability to install additional engines for testing purposes only.
Ali noted that the Passport is very representative of future engines being studied, including a core similar to the latest commercial jet engines. The key, says Gaël Méheust, CEO of CFM International, is how to convert LH2 into a gas and how to modify the combustion chamber accordingly. “The Passport would solve this problem very well. We could have used the LEAP, but due to its larger size and heavier weight, it required more structural engineering to fit in.” Ali said that expanding from the Passport to other engines is GE Aviation and CFM know how to do things. The key, he said, is to understand the changes caused by hydrogen combustion, especially in the core, and to establish data points so that the team can develop the solutions needed for future hydrogen-based powerplants.
What materials will be used for the fuel lines and seals of the H2 engine? Given the high temperatures that Ali pointed out, this could indeed be an issue. FM responded that both GE and Safran have a wealth of materials and technologies for handling high temperatures and will be looking into all of them, from metal alloys and coatings to CMC.
Why put the engine on top of the fuselage and what modifications will the A380 use as a test bed? Klauke explained that the location of the rear wing on the top of the fuselage allows for enough space and clean air to measure atmospheric conditions, emissions, etc., as well as engine operation and fuel delivery systems inside the aircraft. The only modification required is to add a struct stub for attaching the Passport engine.
The size of the four tanks and the safety of their operation? Even though each tank will carry 100kg of LH2, they won’t fill the entire plane, or even the main deck, but they’ll be enough to power the test engines and provide meaningful data during flight demonstrations, Klauke said. On the safety front, CFM said it will first conduct ground tests and only after these are complete will the system be installed for flight testing with Airbus.GE Aviation’s Ali noted that his company has more than 8 million hours of experience with internal combustion engines using fuels with up to 100% H2 content via land-based stationary gas turbines for utility-scale power applications, so it understands how to use it safely H2 based fuel.
Is the timing of the testbed consistent with the original ZEROe timeline, and which aircraft configuration will be selected for service by 2035?Crook said it does support the latest schedule. She noted that the H2 demonstrator will fly by the end of 2026, which would allow technology selection to be completed in 2027.The configuration of Airbus’ first ZEROe aircraft will be finalized by the end of the decade, Klauke said. Airbus is working on three to four configurations with 100 to 150 passengers and a range of 1,000 to 2,000 nautical miles, she said. Each is associated with certain technology choices – some with fuel cells, others with direct H2 combustion. “What we do at Airbus is to mature these technology bricks and then make our choices,” Klauke said.
GE Aviation’s Ali pointed to RISE’s announcement last summer that all engines developed in the future will be able to run on Sustainable Aviation Fuel (SAF) and/or H2, regardless of their architecture. Klauke said it must be determined whether an open fan engine using the H2 can be developed, but this flight test program will help prepare for those decisions and developments.
Upcoming and first flight 787 relies on innovation in composite materials and processes to achieve its goals
Compared to traditional materials such as steel, aluminum, iron and titanium, composites are still in their infancy and are only now being better understood by design and manufacturing engineers. However, the physical properties of composites – combined with their unrivaled weight – make them undeniably attractive.
Take a look at the process by which precursors are turned into carbon fibers through careful (and mostly proprietary) manipulation of temperature and tension.

Post time: May-10-2022

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