Aerospace companies have been trying for years to create a solar-powered plane that can fly at high altitudes for years at a time, and now Boeing has come up with an unorthodox design that just might work.
If it does work, that would smooth the way for an application that Facebook and Google are working on as well: sending up high-flying drones that can loiter over a fixed space on Earth to serve as a link for broadband communication services. It almost goes without saying that the concept could have military applications as well.
Last month, engineers at Boeing Phantom Works in California filed a patent application for an electric-powered plane with solar cells covering its wings, including crazy-looking winglets that stick up from the ends. A video from PatentYogi shows off the design, as well as how it could be put to use to deliver Internet, phone and video – even in remote regions where cable can’t be laid.
The quest to create solar-powered electric planes goes back at least to 1980 with the creation of the MacCready Gossamer Penguin, and the field has grown with the rise of lightweight composites and more efficient photoelectric cells. The best-known example is Solar Impulse 2, which is in the midst of a round-the-world flight and should be flying from Pennsylvania to New York City any day now.
Thanks to its bank of batteries, the single-pilot Solar Impulse plane can fly for days at a time as long as there’s sunny, summery weather. But it’s trickier to create a robust “atmospheric satellite” that can fly on its own at high altitudes for, say, months or years at a time.
Between 1995 and 2001, NASA and its industrial partners developed a series of solar-powered prototypes that could fly as high as 96,863 feet – but they couldn’t stay in the air for long.
More recently, Boeing Phantom Works worked with the Pentagon’s DARPA think tank and Britain’s QinetiQ on an electric-powered spy plane called SolarEagle, which was supposed to have a nearly 400-foot wingspan and fly continuously for as long as five years at a height of 60,000 feet. That project was canceled in 2012.
Airbus is still working on a similar project called Zephyr.
In last month’s patent application, Boeing says the solar-cell winglets should give its design the edge for long-endurance flight. The feature addresses one of the big issues for power generation in flight: how to maximize the amount of solar energy soaked up by the cells on the plane’s wings.
The winglets can be angled more directly into the sunlight, even when the sun is at a low angle. That’s particularly desirable for flights at higher latitudes during winter. For example, Hood River, Ore., gets only a little more than eight hours of daylight at the winter solstice, and the sun doesn’t get any higher than around 21.5 degrees above the horizon on that day.
“This means that it is desirable to effectively collect solar energy for relatively few hours per day and from very low sun angles, while still collecting and providing sufficient energy to keep the airplane aloft at the desired altitude,” Boeing says in the patent application.
Will Boeing build it? That’s up in the air, so to speak. But it’s clear that the Phantom Works has the know-how to proceed: One of the inventors is Blaine Rawdon, who has been involved in solar-powered plane projects going back to the Gossamer Penguin. His co-inventor is Aaron Kutzmann, who has a long list of patents for gizmos including space tractors.
