I didn’t learn to fly in gliders, but soaring was an early part of my training. I earned my “Commercial Sailplane—Air Tow” rating in 1970 at El Mirage, Calif., though I never did figure out what to do with a commercial glider rating. (“Briegleb Flight 14 leaving from Gate 1 nonstop from El Mirage, Calif., to El Mirage, Calif.”)
Gliders introduced me to a whole new world of flying, but once I was licensed, it was tough to log additional hours, no matter how much I loved it. El Mirage Dry Lake is about 70 miles from my home, so I first had to fly there in order to fly gliders, then enjoy a few tows to altitude in the Blanik, jump back in my Bellanca and fly home, an expensive and time-consuming process. Throw in a few supplemental flights in various sailplanes in the intervening 40 years, and I have probably only about 40 hours of glider time.
But those 40 hours were universally great fun, making me wonder why no one ever wrote a book titled Zen and The Art of Flying Sailplanes.
If you live in an urban area (and they don’t get much more urban than the Los Angeles Basin), learning to fly sailplanes can be a difficult task. Soaring often is regarded as more of an art than a science, and its proponents frequently analogize it to sailing versus powerboating. Practitioners of the sport sometimes regard it as the holy grail of flying.
My entry-level soaring experience was confined to El Mirage Airport at El Mirage Dry Lake, near Edwards AFB, both before and after I was licensed. I was flying a Czechoslovakian Blanik L-13, an all-metal sailplane with a glide ratio of 28 to 1. That’s about three times more efficient than the L/D of most powered general aviation aircraft and seven times better than the Space Shuttle’s best effort, but it’s not even close to high performance in sailplane terms. Some of the best competition sailplanes fly with glide ratios as high as 70 to 1 or more. That’s 70 feet forward for every foot of altitude loss.
Fortunately, the dry lake provided a hedge for students who can’t manage their altitude properly. The huge, wide, flat expanse of dry dirt provides a universe of landing sites, and the tow plane can usually land and tow you home in a few minutes.
With no form of motive power on the nose or wings, you might expect gliders to have limited altitude capability, but I quickly learned that’s not the case. Finding a good thermal can be a problem, and staying in it presents an additional challenge, but on rare occasions, you can sometimes spiral up to 10,000 feet or more.
Some people dream of even higher altitudes without an engine, piston, jet, rocket or rubber band. Einar Enevoldson, an experienced USAF test pilot with time in practically everything up thru the SR-71 Blackbird, launched the Perlan Project in the early 2000s. He joined forces with meteorologist Dr. Elizabeth Austin in analyzing the possibility of flying a mountain wave to 90,000 feet, then enlisted support from publishing magnate Steve Fossett, who agreed to fund the project.
After several years of trying, the two explorers took a tow to 10,000 feet above the Patagonian Desert of Southern Argentina, cut loose and ascended toward the high sky. Fossett and Enevoldson finally set the ultimate glider altitude record of 50,671 feet in 2006 above the Andes Mountains, eclipsing the old record of 49,007 feet set over Mt. Whitney, Calif., in 1986.
Fossett and Enevoldson were wearing full pressure suits loaned to them by NASA, and the suits protected them from the low atmospheric pressure and the -80 degree F cold. The only reason they aborted their flight was that the suits had expanded so dramatically in the thin air 10 miles above sea level, the two pilots could barely reach the controls.
Now, Enevoldson hopes to continue the quest for extreme altitude with an all-new glider, the Perlan Project II, a 1,700-pound aircraft with an 84-foot-span wing. The Perlan I sailplane was a modified, DG505M, European glider, but problems with the first flight proved the team needed a fully pressurized, purpose-built aircraft designed specifically for high-altitude flight.
Accordingly, the new glider will offer a carbon-fiber cabin inflated to 8.5 psi. There’s essentially no atmosphere at 90,000 feet, so an 8.5 psi pressure system will provide an Earth cabin altitude of about 14,000 feet MSL, easily survivable without supplemental O2. Perhaps more than coincidentally, a 90,000-foot altitude above Earth is roughly the equivalent of Mars atmosphere at average ground level. (There’s no sea level on Mars.)
Enevoldson believes flight in the high stratosphere is possible, though that view isn’t shared by everyone. In fact, some meteorologists refer to that high region irreverently as the “ignorosphere,” because it has been mostly ignored by researchers. No current airplane can sustain flight at this altitude, because the air is too thin to support anything more than short duration pop-up flights by research aircraft.
For that very reason, the Perlan II will need to maintain about Mach .50 to avoid a stall. Vne will be 377 knots true airspeed (about 56 knots indicated). The Perlan II will need to be extremely clean aerodynamically since there’s so little atmosphere at FL900, any drag will be a major disadvantage.
Windward Design of Bend, Ore., is working diligently on the Perlan II, and the aircraft will be built hell for stout, with stress limits of +6 and -4 Gs, only appropriate considering it will need to fly in a region where little is known about turbulence. Remember, this will be an aircraft without an engine, so lift will only be provided by thermal or mountain wave activity.
After Fossett’s death in 2007, funding slowed dramatically. Enevoldson’s team nevertheless continues work on the Perlan II, designed specifically for a trip to 90,000 feet MSL in semi-pressurized comfort. So far, they’ve spent $2.8 million on the project, and Enevoldson hopes to launch the record flight by 2015.
The former test pilot has good reason to believe the flight is possible, partially because of a combination of the southern jet stream and the South Polar vortex that circles the Earth at certain times of the year, 60-70 degrees south of the equator.
If Enevoldson is successful, the Perlan II will be used to study the polar vortex and its influence on global weather patterns. Enevoldson also hopes to be able to take a variety of atmospheric measurements of various gases present in the Ozone hole at extreme altitude.
Enevoldson suggests the aircraft could be used for a variety of other research projects in the 90,000 to 100,000-foot range of the stratosphere.
And remember, that’s without an engine.