THE PERFECT AIRCRAFT

All aircraft are a bundle of compromises.  Some designs fly well at low altitudes but are unable to sustain flight at high altitudes.  Some are optimized for high altitude but fly poorly at low altitudes.  Some are designed to carry heavy loads and some carry little more than a pilot.  The Perlan 2 is an airplane designed to fly the most efficiently at 50,000 feet but fly acceptably at sea level and at 90,000 feet.  It has 84 foot long wings, can carry two pilots, scientific instruments, life support and two safety parachutes and have the same weight as a 1967 Volkswagen Beetle.

Perlan 2

Construction Process

Perlan 2, benefitting from the lessons learned on Perlan 1’s ascent, incorporates a pressurized cabin to allow its pilots to enjoy unencumbered flight, with full control over stick and rudder, and many small switches. The cabin pressure of 8.5 pounds per square inch (psi) gives a cabin atmosphere equal to flight at about 14,000 feet.  With an empty weight of 1,500 pounds, and a wing area of 262 square feet, the 84-foot span machine is amazingly light for the structural strength required for stratospheric flight.

With more wing area than a conventional sailplane, it would stay aloft, but never compete with such craft at lower altitudes. But in the thin air at 90,000 feet, with 98 percent of the earth’s atmosphere beneath it, it will be unrivalled. Because it carries two into a very hazardous realm, it is equipped with specialized equipment, including dual-redundant oxygen rebreathers, a drogue parachute to allow rapid descent in the unlikely emergency, and a ballistic chute for a lower-altitude emergency descent.

Statistics

Crew 2
Cabin Pressure 8.5 PSID
Empty Weight 1500 lbs
Gross Weight 2000 lbs
Wing Span 84 ft
Wing Area 263 sq ft
Aspect Ratio 27
Wing Incidence 1.5 °
Horiz. Tail Incidence -0.5 °

Equipment

To do scientific research at the edge of space while keeping the crew safe the Perlan 2 has been equipped with:

  • Cabin pressure regulator and air bottle      
  • Re-breather system for life support      
  • Tail drogue parachute and BRS parachute     
  • High altitude radar transponder by Sandia Aerospace
  • Instrumentation and lighting to fly at night  by Whelen Engineering      
  • Data loggers to validate world record, LX-9000      
  • Scientific instrumentation      
  • Cameras to record meteorological conditions      
  • Lithium-ion rechargeable batteries       
  • Telemetry to communicate with mission control and scientists on the ground

Basics of Gliding

Gliders are a simple and elegant way to fly. They fly in harmony with the atmosphere rather than using engines to overcome gravity and weather. The glider harnesses the natural flow and poser of a complex atmosphere and gains height by finding “lift” or air rising faster than the natural sink rate of the glider. Gliders are quiet and graceful. Ever since our species has dreamed of flight we have imagined doing it like birds, just wings and our wits, dancing among the clouds.

There are three main types of rising air, or lift, used by glider pilots to soar above the earth:

WAVE LIFT

Wave lift is similar to ridge lift in that it is created when wind meets a mountain. Wave lift, however, is created on the leeward side of the peak by winds passing over the mountain instead of up one side. Wave lift requires a good wind over the ridge and stable air. As long as the wind above the ridge blows constantly at a higher and higher velocity with increased altitude the wave will propagate upward. The Perlan 2 will use wave lift to reach 90,000 feet.

THERMALS

Thermals are columns of rising air created by the heating of the Earth's surface. As the air near the ground is heated by the sun, it expands and rises. Pilots keep an eye out for clouds that mark the rising air and terrain that absorbs the sun more rapidly than surrounding areas and “kick off” thermals. Gliders can soar these spiraling columns of air up the base of the clouds.

RIDGE LIFT

Ridge lift is created by winds blowing over mountains, hills or other ridges. As the air goes over the ridge, it is deflected upward and forms a band of lift along the windward side of the slope. Gliders flying ridge lift stay close to the ridge.

Perlan 1

Construction Process

Perlan 1, a DG Flugzeugbau DG505M, originally carried a two-stroke engine for self-launching. That was replaced with oxygen tanks, scientific instruments, and non-rechargeable “primary” batteries for powering the radio, oxygen regulators and flight instruments. The sailplane was then towed to release altitude by a conventional tow plane.

The wide cockpit was certified to carry heavy loads, but was still a tight fit for pilots Steve Fossett and Einar Enevoldson.& Because the airplane was not pressurized, the pilots wore spacesuits borrowed from NASA, which presented difficulties in permitting full control movements.

Statistics

Crew 2
Cabin Pressure n/a
Empty Weight 860 lbs
Gross Weight 1389 lbs
Wing Span 59 ft
Wing Area 179 sq ft
Aspect Ratio 19.52
Max Speed 168 mph
Wing Loading 7.8 lb/sq ft

Equipment

To reach 50,000 feet while keeping the crew safe, the Perlan 1 was equipped with:

  • High altitude radar transponder by Sandia Aerospace
  • Instrumentation and lighting to fly at night  by Whelen Engineering
  • Data loggers to validate world record, LX-9000
  • Scientific instrumentation
  • Cameras to record meteorological conditions
  • Lithium-ion rechargeable batteries
  • Telemetry to communicate with mission control on the ground