By Cameron Chai
Students belonging to the Terrassa School of Industrial and Aeronautical Engineering (ETSEIAT) of the Universitat Politècnica de Catalunya BarcelonaTech (UPC) have together designed Spain's first unmanned solar plane – the Solar Endeavour UPC, using a technology developed by them.
The students, Joaquim Creus Prats, Josep Fernández Coll, Carles Felip Aragón, Marta Marimon Mateu, Arnau Pons Lorente, IgnacioPedrosa Lojo, and Xavier Serena Alòs formed the ETSEIAT Trencalòs team.
Designing an energy management system (EMS) and incorporating solar cells in the wings of the plane were the main goals of the team. They spent 18 months on the project collaborating with GTD Sistemas de Información, ROFIN IBERIA, Heliene, The Manresa Technology Centre, Airtech Vacuum Solutions, CATUAV, Club Sedis and the International Centre for Numerical Methods in Engineering.
Solar plane EMSs have strict specifications and are not available freely. The team developed an EMS, which adhered to stringent operational requirements. They designed and implemented an electronic circuit using high quality components and developed an auto-control algorithm to maximize the autonomy of the aircraft. The EMS had to distribute the power from the batteries and solar cells to the plane’s motor and also provide the maneuverability needed for controlling the plane from the ground. It has to manage different types of flight situations, such as atmospheric changes, strong winds, downbursts, reduction in solar intensity and climbing and descending.
Solar cells are fixed on to the wings and tail of solar planes. The cells had to be adapted to fit onto the wing’s curved, aerodynamic surface. The monocrystalline silicon used for making solar cells is extremely fragile and tends to break. The cells are normally 0.2 mm thick and the Spanish team built a panel, which along with the protective coating had a total thickness less than 1 mm.
CATUAV provided remote control and telemetry systems, which included GPS navigation, flight-assistance instrumentation and a video camera that provided real-time data to the control station on the ground.
The Solar Endeavour UPC has a cruising speed of 58 km/h with a speed of 90 km/h. It weighs 11.3 kg and has a length of 1.8 m and a wingspan of 5 m. The plane has five batteries that have a capacity of 40 Ah and weigh 2.5 kg. The average motor consumption is 11 A. The motor has a maximum power of 500 W and a cruising motor power of 127 W.
The solar plane flew continuously for 5 h 48 min at the Sedis aero club located in Seu d'Urgell. The solar panels provide over 50% of the power required during peak sunlight hours, while the batteries can supply the power when there is no sunlight source.
Solar planes enhance the capabilities of unmanned aerial vehicles (UAV). They can fly over the desired areas for days together. They can be used for scientific missions, communications in isolated areas, traffic control and prevention of forest fires. The ETSEIAT Trencalòs project demonstrates the potential of solar planes for civilian applications.