GNC Lecture: Year-Round Solar Powered Stratospheric Flight 6 January 2020 0930 - 1030
Nearly 1/3 of the world’s population, living mostly within +- 20 degrees of the equator and in other remote areas, have no cell phone connectivity due largely to the lack of communication towers. Many studies have been conducted that conclude it is impractical to provide connectivity by conventional means using any combination of communication towers, satellites and cooper or fiber optic cables. Studies have also explored the possibility of using balloons to create perpetual towers-in-the-sky at altitudes above 60,000 feet where there are no FAA regulations regarding how they may be flown. High altitude balloons are more expensive and consume far more energy than fixed wing aircraft in maintaining position under windy conditions. There are also other high altitude military and commercial needs for achieving a long endurance flight capability.
This talk will survey recent designs for achieving sustained solar powered aircraft flight at or above 60,000 feet. It will explain how these designs are fundamentally limited by present day solar cell, battery and light weight composite airframe design technology. A possible solution to this challenging problem will be described that involves Vortex Seeking Formation Flight (VSFF) whose purpose is to minimize formation drag. VSFF takes advantage of the vortex that trails from the wingtips of a lead aircraft. This is commonly seen in nature by observing the formation flown by a flock of geese. In order to accomplish this precisely with a formation of aircraft, adaptive autopilot logic is required to first bring a group of aircraft into formation from arbitrary starting positions, and then once in formation to commence seeking an ideal relative positioning with respect to the nearest aircraft forward in the formation. This presentation will explain why this is the only way (presently) to achieve year-round perpetual solar powered flight at reasonable latitudes, and illustrate several reasonable design concepts that can provide a pathway for its achievement.
Anthony J. Calise
Professor (ret.), Georgia Technical School of Aerospace Engineering, AIAA Fellow