Comment on “Flying by the Sun only: The Solarcopter prototype” by Shaheed et al. [Aerosp. Sci. Technol. 45 (2015) 209–214]

Abstract

We refer to the paper “Flying by the Sun only: The Solarcopter prototype” by Shaheed et al. [1], which describes a quadcopter which can purportedly “continuously fly in sunlight without any need for energy storage” and which attained a supposed thrust-to-weight ratio of 1.36:1. Although we have diligently tried, we have not been able to reproduce this result of the paper. Based on our analysis and understanding of information in the paper and measurements of components purchased to try to replicate the results, we believe that the aircraft as described likely had a thrust-to-weight ratio less than 1, and that the aircraft described would not be able to fly stably and continuously above the ground effect under natural sunlight. In addition, several issues with the publication have impeded our ability to replicate the results. Particularly, the photographs of the aircraft in the publication are not true representations of the aircraft described in the text, and key components identified in the photographs are inconsistent with those mentioned in the text.