Limitations in total system weight for solar aircraft designed for infinite flight

This paper presents a way to determine a weight feasibility criterion for solar-powered airplanes designed to perform infinite flight. The criterion is fast and simple to compute and can be used for initial assessments on aircraft design and mission planning. The derivation starts with taking solar cell weight and efficiency into account, then is expanded to energy-storage and propulsion group considerations. This step-by-step approach can then be used to determine a feasible weight and predict system performance properties. The presented criterion was validated using data from three different unmanned solar airplanes. SkySailor, a 3.2m wingspan, 2.55kg light small type of unmanned airplane, AtlantikSolar weighting 6.7kg and with a wingspan of 5.65m and the Helios HP01 Prototype, with 75.3m wingspan and 929kg weight one of the largest unmanned solar aircrafts. All three validations prooved the concept and granted additional performance estimations.