The Perlan Project (so named for the pearlescent stratospheric clouds in Scandinavia) is the brainchild of Einar (pronounced “Ay-nar”) Enevoldson, a former test pilot for the Royal Air Force, U.S. Air Force, and NASA. He’s piloted dozens of aircraft, including the F-86, F-14, and F-111. He’s also flown one-of-a-kind experimental craft, among them the odd, oblique-wing AD-1 and the X-24B lifting body. During the golden age of flight research, Enevoldson was a member of the elite community that included Chuck Yeager, Scott Crossfield, and other luminaries pushing the bounds of aviation.
Enevoldson retired from NASA in 1986 and went to work as a test pilot for Grob Aircraft in Germany, where he flew the Strato 2C, a high-altitude research aircraft developed by the German Aerospace Research Center, DLR. That project was canceled, but the work piqued his interest in high-altitude flight. He recalls walking down a corridor at DLR’s offices near Munich in 1992 and noticing an image tacked outside the office of an atmospheric researcher. Made with LIDAR (light detection and ranging), the image showed what Enevoldson recognized as mountain waves, but these were far bigger and extended much higher than any he had seen before. Standing in front of the image, Enevoldson immediately saw the potential to do something unprecedented. He realized that if the waves were associated with enough wind, they could propel a glider to heights previously thought unobtainable. “I really thought at this moment that this could end up being my life’s work,” he says. High-altitude glider pilot Doug Perrenod, a Perlan project team member, says the realization was the project’s eureka moment.
Mountain waves can be compared to water in a stream swiftly running over a boulder. Air is a fluid, and once winds crest over a mountain ridge and roll down the mountain’s other side—the lee side—they push up into a wave. With the right conditions, the wave can rise thousands of feet higher than the summit of the mountains.
The presence of the waves are often indicated by clouds that are lens-shaped, or lenticular. Early aviators quickly learned to avoid flying near or under the convex clouds because they are associated with severe turbulence and downdrafts. But as far back as the 1930s, glider pilots discovered they could use the powerful updrafts to climb to great heights.