Aeronautics and Aeronautics – Small aircraft test sustainable drives for large – sporting aircraft

Friedrichshafen (dpa) – Snow White, a little more than 21 meters wide and weighing up to 1.5 tons, is the hope of climate-friendly aviation, which landed on Lake Constance in mid-April. HY4 is the name of the experimental aircraft with a fuel cell and battery system, which completed its first flight years later at Stuttgart Airport: 124 kilometers to Friedrichshafen.

The HY4 will be on display there from Wednesday to Saturday at the Aero Air Show – as one of many ideas on how aviation can become “greener”.

The trade fair with 633 exhibitors from 34 countries focuses not on commercial aviation but on general aviation, i.e. above all recreational and commercial aviation. But it is “a large-scale flight test lab for alternative engines such as electric motors,” says a spokesperson for the show.

The Pipistrel Velis Electro, the world’s first certified battery-powered electronic aircraft, and the eMagic One, an electronic wing vertical tandem take-off aircraft from Germany, which looks like a mixture of UAVs and sports aircraft, can be found on display on Lake Constance. The list of innovations also includes many other electric and hybrid aircraft, sustainable drivetrains and battery systems.

Fairly small electronic planes

But for now, the role of electronic aircraft will likely be limited to small aircraft such as private aviation, says Markus Fischer, head of the aviation department at the German Aerospace Center (DLR). In order to propel a commercial airliner over thousands of kilometers, batteries would have to have a much higher energy density – and they would be very heavy.

“As things stand today, the majority of an aircraft’s weight will be determined by the batteries,” Fisher says. So far, this basic problem is not expected to change soon.

On the other hand, sustainable fuels, which are referred to in aviation as sustainable aviation fuels (SAF), are promising. Until now, it was mainly made from organic waste such as used cooking oil or meat and fish by-products. “It works,” Fisher says. But the quantity is very limited so far.” Currently, the SAF can cover only about one percent of the fuel needed to fly around the world.

sustainable fuel

Additionally, SAF is three to seven times more expensive than conventional kerosene, Fisher says. According to the will of the European Union Commission with its “Fit for 55” initiative, 2% of fuel used in aviation should be sustainable by 2030.

“We think the five percent is also possible,” Fisher says. “However, the biggest hurdle is to provide an adequate supply. Scheduled services will almost certainly be provided before smaller services, such as general aviation, reach the feeding trough.”

For example, aircraft manufacturer Airbus is increasingly dependent on the Sudanese Armed Forces. According to the company, up to 50 percent of SAF can be added to conventional kerosene in all modern Airbus aircraft, and the proportion should be 100 percent by 2030. “On short and medium-range routes, sustainable jet fuel is just a solution,” Airbus said. temporary”. Later, hydrogen technology could enable zero-carbon-emissions flights there.

DLR expert Fisher also sees good opportunities for hydrogen engines in this size class. “There’s more tendency to use that on planes that don’t fly that far – maybe 1,500 kilometres.” In order to get a lot of energy in a small space, hydrogen must be stored in tanks as a gas under high pressure or as a liquid at low temperatures, Fisher says. This requires relatively heavy tanks.

The operator of the HY4 experimental aircraft, Stuttgart’s H2Fly company, wants a hydrogen-electric Dornier aircraft with 40 seats in the air for test flights by 2025. “Ultimately, the project should result in the production of a series of passenger aircraft,” says a company spokesperson. The target range is about 2,000 kilometers, for example, to create flights from Warsaw to Paris.

Set the drive

According to the company, the biggest problem is adapting the drive to this size. There are suitable products from the automotive industry for the 120 kW fuel cell in the HY4 test plane. For Dornier 328, the required power is more than a dozen times greater – about 1.5 megawatts. A spokesperson for the company says its parts are “very few at the moment, especially not for aviation”. “That’s why we’re doing real pioneering work here.”

As Fischer, an expert on the DLR, sees there is no short-range alternative to large jets in fuel cells. “It’s a long way to go. But it makes sense to start small and show the feasibility.” In order to do so in Lake Constance, operators of the HY4 test aircraft are bringing their “green” hydrogen tank options from Stuttgart.

The numbers are almost the same as they were before the epidemic started

But even if many sustainable engines remain elusive in chain production: after the corona-related slump, the overall aerospace business is also doing well with conventional combustion engines. At the end of 2021, deliveries were back to numbers before the pandemic began, a spokesperson for the International Federation of Industry, the General Aviation Manufacturers Association, said.

A spokesperson for the trade fair said that digital networking in times of Corona in particular has led to an increased need to meet in person during important negotiations. In light of airlines’ reduced flight schedules, “only business aviation provides the necessary transportation for people to meet.” After all, it takes several days to get from Oslo to Palermo using other means of transport.

© dpa-infocom, dpa: 220426-99-49318 / 5

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