Design And Investigation Of Flat–Upper–Surface Airfoil

Abstract

Attempts to build solar High Altitude Long Endurance (HALE) airplanes are more and more frequent. In the future such airplanes may appear very useful for the economy because they may replace geostationary satellites in several applications for a fraction of cost. Unfortunately, necessary data on altitude effect on photovoltaic cells and batteries performance are not easily available. Therefore, flying testbed for their inexpensive testing is needed. Flat–upper surface airfoil was designed for application in small UAV dedicated for photovoltaic cells investigation at various altitudes. It should enable installation of rigid cells on the top of the wing without significant reduction of aerodynamic performance. It should also decrease a risk of damage of flexible cells due to the significant bending of long aspect ratio, elastic wings. This paper contains description of the design methodology, design assumptions and obtained results. Moreover experiment undertaken to evaluate the design is described as well. The wind tunnel and a semi–span model used for this experiment are presented together with obtained results. The model has exactly the same structure as envisaged structure of UAV, so flexibility of the wing is taken into account.