Luminati Aerospace claimed this week that its Substrata solar-powered aircraft can remain aloft in the stratosphere indefinitely via automated vortex seeking formation flight. The company said computer simulations that validated the theory were verified by flight data collected when its solar-powered aircraft intercepted and then flew in formation trail with Solar Impulse-2 shortly after it departed from New York on the transatlantic portion of its historic round-the-world flight in 2016.
Data from the flight matched computer simulations that show that a formation of its aircraft can fly perpetually all the way to 50 degrees latitude, according to the company. The data indicated an average 79 percent reduction in power required for the trailing aircraft.
The idea for vortex formation flying came from studying migratory geese. The lead bird sheds wingtip vortices, which are harvested by the trailing bird positioned in the uprising portion of the swirl. As a result, trailing geese expend less energy and have up to a 35 percent reduction in heart rate. During flight, the lead goose position rotates among the flock.
Company CEO Daniel Preston said four aircraft flying in a diamond formation is the most efficient method of taking advantage of the phenomenon. “The trailing point of the diamond offers the opportunity of a double energy harvest by taking advantage of the two wingtip vortices that trail from the respective right and left wingtips of the aircraft at the outermost points of the diamond,” he noted.
Preston said the formation conveys other benefits to aircraft, including the ability to service aircraft one at a time while maintaining the formation; larger and better payload distribution, which is important for communication and synthetic aperture radar applications; and easier ground handling by allowing smaller and stiffer airframe construction and the addition of landing gear. Preston claimed that the typical solar aircraft is of fragile construction and requires multiple ground handlers to launch and land.
Luminati said applications for perpetual flight include internet delivery in the underdeveloped world and enhanced national security capabilities. The company plans to build larger aircraft with the capability of carrying heavy commercial communications and intelligence, surveillance, and reconnaissance payloads.