Russia is preparing to fly the first high altitude unmanned aerial vehicle (UAV) to remain in the air with solar energy alone for tests in the stratosphere. Sergey Lemeshevsky, General Manager of the Russian Lavochkin Company said the tests in the stratosphere (between 20 and 50 km altitude) will be completed before the end of the year if the authorities approve.

Speaking to the Russian Izvestia newspaper, Lemeshevsky stated that all tests were completed except for the high altitude flight. The General Manager stated that for the flight in the stratosphere, a formal authorization is required from the Rostov Zone Center of the Unified Air Traffic Management/EU ATM.

The solar-facing side of the UAV called “Aist” with LA-252 code is covered with solar panels from the side. The daytime operations of the UAV  will be powered by direct solar energy and in the night, the vehicle will use the rechargeable batteries which store the solar energy they absorb during the daytime. Two electric motors keep the IHA in the air.

With a wingspan of 23 m and a take-off weight of 125 kg, the UAV is planned to be demonstrated for potential customers, especially the Russian Armed Forces, after trials in the stratosphere. The UAV can carry 25 kg-payload.

Stratosphere: The stratosphere is the layer of the earth's atmosphere above the troposphere, extending to about 20 to 50 km above the earth's surface where horizontal air movements can be observed. Vertical air movements do not occur as there is no water vapor. Stratospheric temperature ranges from -55 to -3 degrees Celsius. As the gravity decreases in the stratosphere, the objects lose their true weight. Ozone is found in the upper parts of the stratosphere and heats this layer as it absorbs energy from incoming ultraviolet radiation from the Sun.