hydrogen aircraft

A hydrogen powered aircraft uses hydrogen fuel rather than fossil fuels such as aviation fuel. Hydrogen can either be burned in a jet engine or can be used to power a fuel cell which generates electricity.

What is a hydrogen powered aircraft?

The drive for a global green future has inevitably asked questions of the aerospace industry, leading to the research around hydrogen powered aircraft. Propulsion and fuel alternatives are being researched, tested and proposed from all corners of the globe. Hydrogen, as a fuel, is a very real prospect and progress is being made at a staggering rate. Aerospace is on an exponential push to reach its own goals for net zero emissions.

The European Union’s research (including Airbus and 34 other partners) called CRYOPLANE assessed the technical feasibility, safety, environmental compatibility and economic viability of using liquid hydrogen as an aviation fuel.

History

In February 1957, a Martin B-57B flew on hydrogen for 20 min for one of its two Wright J65 engines. On 15 April 1988, the Tu-155 first flew as the first hydrogen-powered experimental aircraft. Boeing converted a 2-seat Diamond DA20 to run on a fuel cell, in 2008. In 2010, the Rapid 200FC concluded six flight tests using gaseous hydrogen. Hydrogen gas is stored at 350 bar, feeding a 27 hp fuel cell powering a 54 hp electric motor along a 27 hp lithium polymer battery pack. On January 11, 2011, an AeroVironment Global Observer unmanned aircraft completed its first flight powered by a hydrogen-fuelled propulsion system.

Developed by Germany’s DLR Institute of Engineering Thermodynamics, the DLR HY4 four-seater was powered by a hydrogen fuel cell, its first flight took place on September 29, 2016.  It has the possibility to store 9 kg of hydrogen, 4×11 kW fuel cells and 2×10 kWh batteries.

 

Hydrogen powering vehicles

Hydrogen has a specific energy that is 3 times higher than aviation fuel and a lower energy density. If hydrogen is available from low-carbon energy sources such as wind or nuclear, its use in aircraft will produce fewer greenhouse gases. Due to the way it is produced, and the relative inefficiencies of its production currently, it is more expensive than fossil fuels. Liquid hydrogen is a known coolant and it has been proposed to use this property for cooling intake air for very high speed aircraft.

 

Hydrogen powered vehicle design

Liquid hydrogen has about four times the volume for the same amount of energy of kerosene fuel. Liquid hydrogen aircraft designs store the fuel in the fuselage, leading to a larger fuselage length and diameter. This lowers the performance due to the larger fuselage size causing more skin friction drag and wave drag. However, hydrogen is about one-third of the weight of kerosene jet-fuel for the same amount of energy. For a Boeing 747-400 this would reduce the takeoff gross weight from 360,000 to 270,000kg. Therefore the performance is a trade-off of the larger wetted area and lower fuel weight.

 

Hydrogen powered spy plane – Boeing Phantom Eye

Phantom Eye is a LH2, automated, high-altitude intelligence and surveillance plane, manufactured by Boeing. The aircraft can maintain flight for over four days. Its remit requires onboard comms, sensors and ultra high technology photographic and imagery equipment. The aircraft is being tested via the U.S. Air Force 412th Operations Group.

Current and past hydrogen planes

  • Lockheed CL-400 Suntan
  • Liquid hydrogen National Aerospace Plane.
  • AeroVironment Global Observer

Current

  • Reaction Engines Skylon orbital
  • Reaction Engines A2 antipodal hypersonic airliner
  • DLR Smartfish
  • Boeing Phantom Eye
  • The Greenliner (TU Delft)
  • The Cryo-V
  • ZeroAviaHyFlyer (fuel-cell)

 

Airbus ZEROe hydrogen aircraft

In 2020, Airbus announced plans for three different hydrogen-fuelled concepts, named ZEROe, with the aim of developing zero-emission aircraft. The aircraft are powered using hydrogen gas turbine rather than hydrogen fuel cells. The first idea is the turbofan design,  able to carry 200 passengers up to 2,000 miles. The aircraft achieves over 800 km per hour.

Another concept is a turboprop aircraft with propellers, carrying up to 100 passengers and features a modified gas turbine, supported by a hybrid electrical motor run by fuel cells.

 

Blended Wing Hydrogen plane design (Flying V)

A third concept, the hydrogen-powered Blended Wing Body design sees the wings and fuselage form one aerodynamic body. This design follows the recent study into the Flying V, via airline KLM and the Delft University of Technology.

Airbus plan to enter service in 2035. This will depend hugely on a robust infrastructure for hydrogen operations, from production to storage and tanking. Hydrogen is only sustainable if produced from green energy. Note that combusting hydrogen still produces water vapour, causing contrails in the skies that have a climate impact. They will not be entirely, 100% green and emission free.

 

Hindenburg disaster

The Hindenburg disaster was an airship crash that occurred on May 6, 1937, in New Jersey, US. The German passenger airship LZ 129 Hindenburg caught fire and was destroyed during its attempt to dock. There were 35 fatalities. A variety of hypotheses have been put forward for both the cause of ignition and the initial fuel for the fire. The publicity shattered public confidence in the giant, passenger-carrying rigid airship.

The Hindenburg departed from Frankfurt, Germany, on the evening of May 3, on the first of 10 round trips between Europe and the US.  Except for strong headwinds that slowed its progress, the Atlantic crossing of the Hindenburg was otherwise unremarkable. Many of the passengers with tickets to Germany were planning to attend the coronation of King George VI and Queen Elizabeth in London. The airship was hours behind schedule when it passed over Boston on the morning of May 6. Advised of the poor weather conditions at Lakehurst, Captain Pruss charted a course over Manhattan Island, causing a public spectacle as people rushed out into the street to catch sight of the airship. After finally being notified at 6:22 p.m. that the storms had passed, Pruss directed the airship back to Lakehurst to make its landing almost half a day late.

Hindenburg disaster timeline

Around 7:00 p.m. local time, at an altitude of 200m, the Hindenburg made its final approach to the Lakehurst Naval Air Station. This was to be a high landing, known as a flying moor. At 7:09 p.m., the airship made a sharp full-speed left turn to the west around the landing field because the ground crew was not ready. At 7:11 p.m., it turned back toward the landing field and valved gas. At 7:18 p.m., as the final turn progressed, Pruss ordered 300, 300 and 500 kg of water ballast in successive drops because the airship was stern-heavy. The forward gas cells were also valved. At 7:21 p.m, at an altitude of 90m, the mooring lines were dropped from the bow. The port line was overtightened as it was connected to the post of the ground winch. The starboard line had still not been connected. At 7:25 p.m., a few witnesses saw the fabric ahead of the upper fin fluttered as if gas was leaking. Several eyewitness testimonies suggest that the first flame appeared on the port side just ahead of the port fin, and was followed by flames which burned on top. Commander Rosendahl testified to the flames in front of the upper fin being mushroom-shaped. At 7:25 p.m. local time, the Hindenburg caught fire and quickly became engulfed in flames. One witness, with views of the starboard side, saw flames beginning lower and farther aft, near cell 1 behind the rudders. Inside the airship, helmsman Helmut Lau, who was stationed in the lower fin, testified hearing a muffled detonation and looked up to see a bright reflection on the front bulkhead of gas cell 4, which suddenly disappeared by the heat. As other gas cells started to catch fire, the fire spread more to the starboard side and the ship dropped rapidly.

Wherever the flames started, they quickly spread forward first consuming cells 1 to 9, and the rear end of the structure imploded. Almost instantly, two tanks burst out of the hull as a result of the shock of the blast. Buoyancy was lost on the stern of the ship, and the bow lurched upwards while the ship’s back broke; the falling stern stayed in trim.

As the tail of the Hindenburg crashed into the ground, a burst of flame came out of the nose, killing 9 of the 12 crew members in the bow. The airship’s gondola wheel touched the ground, causing the bow to bounce up slightly as one final gas cell burned away. Although the hydrogen had finished burning, the Hindenburg‘s diesel fuel burned for several more hours.

In the days after the disaster, an official board of inquiry was set up at Lakehurst to investigate the cause of the fire. The investigation by the US Commerce Department was headed by Colonel South Trimble Jr, while Dr. Hugo Eckener led the German commission.

 

 

Recent category posts

References

  1.  Matlack, K. H.; Kim, J.-Y.; Jacobs, L. J.; Qu, J. (2015-03-01). “Review of Second Harmonic Generation Measurement Techniques for Material State Determination in Metals”. Journal of Nondestructive Evaluation34 (1): 273. doi:10.1007/s10921-014-0273-5ISSN 0195-9298S2CID 39932362.
  2. ^ Mostavi, Amir; Kamali, Negar; Tehrani, Niloofar; Chi, Sheng-Wei; Ozevin, Didem; Indacochea, J. Ernesto (2017). “Wavelet Based Harmonics Decomposition of Ultrasonic Signal in Assessment of Plastic Strain in Aluminum”Measurement106: 66–78. doi:10.1016/j.measurement.2017.04.013.
  3. ^ U.S. Patent 3,260,105 for Ultrasonic Testing Apparatus and Method to James F. McNulty at lines 37-48 and 60-72 of Column 1 and lines 1-4 of Column 2.
  4. https://www.ndt.net/ndtaz/content.php?id=347
  5. https://www.dekra.com/en/ultrasonic-testing/
  6. https://en.wikipedia.org/wiki/Ultrasonic_testing
  7. https://www.dw.com/en/at-airbus-a-hydrogen-powered-aircraft-takes-shape/a-55051579
  8. https://en.wikipedia.org/wiki/Hindenburg_disaster
  • Albert S. Birks, Robert E. Green, Jr., technical editors ; Paul McIntire, editor. Ultrasonic testing, 2nd ed. Columbus, OH : American Society for Nondestructive Testing, 1991. ISBN 0-931403-04-9.
  • Josef Krautkrämer, Herbert Krautkrämer. Ultrasonic testing of materials, 4th fully rev. ed. Berlin; New York: Springer-Verlag, 1990. ISBN 3-540-51231-4.
  • J.C. Drury. Ultrasonic Flaw Detection for Technicians, 3rd ed., UK: Silverwing Ltd. 2004. (See Chapter 1 online (PDF, 61 kB)).
  • Nondestructive Testing Handbook, Third ed.: Volume 7, Ultrasonic Testing. Columbus, OH: American Society for Nondestructive Testing.
  • Detection and location of defects in electronic devices by means of scanning ultrasonic microscopy and the wavelet transform measurement, Volume 31, Issue 2, March 2002, Pages 77–91, L. Angrisani, L. Bechou, D. Dallet, P. Daponte, Y. Ousten
  • Charles Hellier (2003). “Chapter 7 – Ultrasonic Testing”. Handbook of Nondestructive Evaluation. McGraw-Hill. ISBN 978-0-07-028121-9.