Engineering Headlines

This aircraft provides for the Internet from the stratosphere

Constantly in the air

The ideas to enable Internet access all over the world are becoming more and more unusual.

Now DLR has launched a solar aircraft for the first time in the stratosphere.

The goal: the aircraft supports satellites in the construction of a comprehensive Internet.

The Elektra-2 aircraft, which has now made its first flight over Payerne near the Lac de Neuchâtel in Switzerland, is really unusual.

The electric aircraft is 8.5 m long and has a span of almost 25 m. Airplane flies alone by electricity from solar cells .

The wings are covered with solar modules on 22 square meters in order to supply the electric drive with electricity. Just as the airplane Solar Impulse has done during its round the world.

After 17 stages, she landed again in the summer of 2016 at the starting point in Abu Dhabi.

Despite the many solar cells on its surface, the Elektra 2 weighs only 420 kg. And the payload with 100 kg is quite substantial, and necessary.

Because the aircraft is to fly around the clock around 20 km in altitude around the clock in order to allow Internet and Earth observation.

So there must be a lot of camera and transmission equipment on board. “We are proud of what has been achieved,” says Dr. Konstantin Kondak of the Institute for Robotics and Mechatronics of the German Aerospace Center (DLR) in Oberpfaffenhofen.

At the same time, Kondak is the development engineer of the DLR spin-off ElektraSolar in Switzerland, which has built the ultralight aircraft.

“With the first flight of the Elektra-2, we have taken an important step towards the application of high-altitude platforms for data transmission and remote sensing,” says Kondak.

In the future, DLR-Autopilot will take control According to DLR, Elektra-2 is the world’s first solar electric aircraft capable of delivering up to 100 kg of payload at an altitude of about 20 km in autonomous operation.

In the coming months, the solar aircraft will go through an extensive flight test and is to fly up to the stratosphere in 2018.

This would be a new record of high altitude for solar electric aircraft.

First, the engineers wanted to prove with the maiden flight over Payerne that the Elektra-2 can fly at all purely electrically and powered by the current from the solar cells.

The test was still on board with a pilot, although an autopilot system from the DLR is to take over the control in the future.

This will allow the aircraft to be fully autonomous in the sky in the future. But until then the Elektra-2 still has to pass many test flights.

Autonomously controlled and without chassis The first test flights are still carried out on board with a pilot and only 50 kg of payload.

The control system developed by the DLR will take over the flight, the pilot has above all control tasks.

The next version of the Elektra-2, which is already under construction, is to fly without pilot longer missions in the stratosphere.

In addition, we plan to fly with a lighter, unmanned version of the Elektra-2, “says Zielschekf Kondak.” We already tested the control technology for the unmanned landing in flight tests in the Allgäu as early as 2016. ” At the same time, the DLR experimented with a large drone, which had to land on a moving car without landing gear.

The experiment was successful!

The advantage of a motor glider without a chassis is obvious: the aircraft saves weight and can accommodate more payloads. Low airports save cost of launching missiles .

The proximity to the Earth of only 20 km allows such aircraft services that cannot offer satellites of this quality.

It is conceivable that such aircraft provide weather and environmental data, build up significantly higher-resolution images of the earth and communication networks.

Even in the case of disasters, the aircraft can provide rescue forces with high-resolution recordings and provide a local communications network when the local network has collapsed.

By way of comparison: the closest in a distance of between 200 and 2,000 kilometers is the orbiting of satellites, earth satellites and weather satellites.

On the other hand, the GPS satellite satellites are on average about 20,000 km from the Earth, the communication satellites Astra and Meteosat even 42,000 km.

And the high altitude platforms save by their proximity to the ground and the ability to fly even considerable costs.

Expensive rocket launchers are not necessary and defects can be repaired easily on the ground.

After all, the aircraft can return to earth and return to the stratosphere after repair.

Height platforms are a key technology

DLR engineer Kondak therefore considers these new aircraft a key technology.

“For the currently particularly popular application perspective of the nationwide Internet from the air, flying high altitude platforms with a much larger bandwidth can be offered to satellites,” says Kondak.

“For all applications, it will be necessary in the future to have sufficiently large and resilient aircraft which can bear the sensor load.

The development of suitable ultralight airplanes thus becomes a key technology. “

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