Solair Case Study: Solitair

1.2.4 Solair I

At the time when the Solar Challenger flew across the English Channel Günter Rochelt was conducting test flights in his Solair I. The Solair I had a much smaller wing area and could therefore not fit enough solar cells on it to collect the energy needed to climb. After some modifications the Solair I made the cross channel flight and was able to reach an altitude of

1000 meters relying only on solar power6. Günter Rochelt later designed a new aircraft called the Solair II for the 1996 Ulm Berblinger Contest. This was a completely different aircraft than the first one and intended to be more practical and user friendly than any of the earlier solar

1.2.7 Solitair

The Solitair was built by DLR Institute of Flight Systems as a proof of concept aircraft in the mid 1990’s. It was equipped with four adjustable solar panels in the same fashion as the

Gossamer Penguin so that it could absorb a maximum amount of solar radiation by always being perpendicular to the incoming sunrays. So far a prototype with a wingspan of 5.2 meter has been built and tested.

1.2.8 The NASA ERAST Program

In 1994 NASA started the ERAST (Environmental Research Aircraft and Sensor

Technology) program in response to an increasing demand for high altitude and long endurance aircrafts. These unmanned and autonomous aircrafts would be able to conduct atmospheric measurements, surveillance mission and serve as a communications relays.

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Graduation Thesis Sheet

NASA was interested in using such an aircraft as an “atmospheric satellite” since it would make it easier to maintain/upgrade and to control its flight path, this for a fraction of the cost compared to a traditional satellite in space. The first aircraft used in the program was the solar cell and

It was equipped with 18% efficient solar cells that charged the batteries and supplied flight critical systems with power. A decision was made to use silicon solar cells with an efficiency of 18% instead of triple junction cells with an efficiency of up to 28%. The reason being that the density of silicon solar cells was at the time one third of the density of triple junction solar cells.

Test flights started in 2005 and it scored several flights of up to 10 hours but it was not until 2008 that it truly demonstrated its endurance capabilities.

1.2.13 Sun Surfer

In 2007 the Sun Surfer was constructed with the help of the conceptual design methodology developed by André Noth during the Sky Sailor Project. The project goal was to study the possibility to increase the endurance of small UAV’s by using solar cells to supply the motor and battery with power. The Sun Surfer was designed with the target to carry 20 grams of payload and be able to fly continuously during favourable weather conditions .

The result of the study was an airplane with a 77cm wingspan and an empty weight of only 120 grams. 1.2.14 QinetiQ -