Aeronautics and aviation – Small planes test stable motion for large ones – Sport

Friedrichshafen (dpa) – snow-white, slightly more than 21 meters wide and weighing up to 1.5 tons is the hope for a climate-friendly flight, which landed on Lake Constance in mid-April.

HY4 is the name of the test aircraft with fuel cells and battery system, which after years at Stuttgart airport has completed its first flight to another place: 124 kilometers away from Friedrichshafen. The HY4 will be shown there from Wednesday to Saturday at the Aero aerial show – as one of many ideas on how the flight can be made “greener”.

The fair with 633 exhibitors from 34 countries does not focus on commercial aviation but general aviation, ie above all leisure and business aviation. But it is “a large-scale aviation testing laboratory for alternative drives such as electric drives,” says a spokesman for the fair.

The Pipistrel Velis Electro, the world’s first battery-powered electronic aircraft, and the eMagic One, a vertical-wing elevated e-tandem aircraft from Germany that looks like a mix of drones and sports aircraft, can be found on display at Lake Constance. The list of innovations also includes many other electric and hybrid aircraft, fixed drives and battery systems.

Use is still limited

For the time being, however, the role of e-aircraft will probably be limited to small aircraft such as e.g. in private aviation, says Markus Fischer, Head of the Aviation Division at the German Aerospace Center (DLR). To propel a commercial aircraft over thousands of miles, the batteries would have to have significantly higher energy densities – and they would be very heavy. “As things stand today, most of the aircraft weight will be determined by the batteries,” says Fischer. So far, it is not predictable that this fundamental problem will change any time soon.

On the other hand, sustainable fuels, which in aviation are called Sustainable Aviation Fuels (SAF), are promising. So far, these are mostly made from organic waste like cooking oil or meat and fish waste. “It works,” says Fischer. “But the quantity is very limited so far.” Currently, SAF can cover only about one percent of the fuel needed in aviation worldwide.

In addition, SAFs are about three to seven times more expensive than conventional kerosene, Fischer says. “According to the will of the EU Commission with its Fit for 55 initiative, two percent of the fuel used in aviation should be sustainable by 2030.” We think five percent is also possible, “he says. Fischer. “However, the biggest hurdle is making a sufficient amount available. Planned services will certainly be served before the small ones, like general aviation, arrive in the food valley.”

Only temporary solution

Aircraft maker Airbus, for example, is increasingly relying on SAF. According to the company, up to 50 percent SAF can be added to conventional kerosene on all modern Airbus aircraft, and the proportion should be 100 percent by 2030. “On short- and medium-haul routes, however, “Sustainable aviation fuels are only a temporary solution,” Airbus said. Later, hydrogen technology could enable CO2-free flights there.

DLR Fischer expert also sees good options for hydrogen drives in this size class. “There is more of a tendency to use it on planes that do not fly that far – maybe up to 1,500 kilometers.” To get a lot of energy in a small space, hydrogen must be stored in tanks as a high-pressure gas or as a liquid at low temperatures, Fischer says. This requires relatively heavy tanks.

The HY4 test aircraft operator, Stuttgart’s H2Fly, wants to have a 40-seat electric hydrogen Dornier aircraft for test flights by 2025. “Ultimately, the project should result in a passenger aircraft manufactured in series, “says a company spokesman. The target range is about 2000 kilometers, for example to create flights from Warsaw to Paris.

True pioneering work

According to the company, the biggest problem is the fit of the disks to this size. There are suitable products from the automotive industry for the fuel cell in the 120 kW HY4 test aircraft. For the Dornier 328, however, more than twelve times the power required – about 1.5 megawatts. Parts for him are “just rare at the moment, especially not for aviation,” says a company spokesman. “That’s why we’re doing a really pioneering job here.”

DLR expert Fischer also sees no short-term alternative to large aircraft in fuel cells. “It’s a long way to go. But it makes sense to start small and show feasibility.” To do this in Lake Constance, HY4 test aircraft operators bring their own “green” hydrogen tank options from Stuttgart.

But even if many hard drives are still a long way off in serial production: After the corona-related downturn, the general aviation business is doing well even with conventional combustion engines. In late 2021, shipments returned to pre-pandemic figures, said a spokesman for the International Aviation Manufacturers Association’s international industry association.

A trade fair spokesman said digital networking especially in Corona times has led to a greater need to meet in person during important negotiations. Given the reduced airline flight schedules, “only business aviation provided the mobility needed for people to meet.” After all, it takes a few days to get from Oslo to Palermo using other means of transportation.

© dpa-infocom, dpa: 220426-99-49385 / 3

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