thumb|Arctic stratospheric cloud (Mother of Pearl cloud)

Perlan Project Inc. is a <!-- 501(c)(3) -->not-for-profit aeronautical exploration and atmospheric science research organization that utilizes sailplanes (gliders) designed to fly at extremely high altitudes.

On 29 August 2006 Steve Fossett and Einar Enevoldson, the pilots of Perlan Mission I, broke the existing altitude record for gliders by soaring up to 50,671 feet (15,460m) in a standard glider using stratospheric waves of air.

The Fédération Aéronautique Internationale has ratified the altitude record of achieved on 2 September 2018, a substantial improvement over the previous year's best altitude of , which was set on 3 September 2017. These flights used the custom designed and built pressurized high-altitude Windward Performance Perlan II glider, sponsored by Airbus. They also collected data about Earth's atmosphere and its ozone layer.

Meteorological basis of the missions

Standing mountain waves are a source of rising air used in the sport of soaring. Riding these waves, similar in some ways to surfing on an ocean wave, has been widely used to reach great altitudes in sailplanes since they were discovered by German glider pilots, including Wolf Hirth, in 1933 in the Riesengebirge. This method uses the powerfully rising and sinking air in mountain waves. Gliders regularly climb in these waves to high altitudes.

Prior to the 4 September 2017 flight, the glider absolute world altitude record stood at 15,460 meters (50,727 feet), which is the altitude reached by Steve Fossett and Einar Enevoldson during Perlan Mission I. The previous record was 14,938 meters (49,009 feet). It was set in 1986 by Robert R. Harris, flying from California City and reaching his record height over Mount Whitney, California. This may be near the limit for standing mountain waves in temperate latitudes, although in unusual meteorological conditions much higher altitudes may be achievable.

Standing waves normally do not extend above the tropopause at temperate latitudes. A strong west wind usually decreases above the tropopause, which has been shown to cap or prevent the upward propagation of standing mountain waves. However, at the outer boundary of the polar vortex, in winter, the stratospheric polar night jet exists. Its wind field can join with the wind field of the polar jet stream. The result is a wind which increases with altitude through the tropopause and upward to 100,000 feet or above. When this conjunction of winds occurs over a barrier mountain, standing mountain waves will propagate through that entire altitude range. Einar Enevoldson, former NASA test pilot, sought to demonstrate the feasibility of riding these stratospheric standing mountain waves. The weather conditions favorable, although not in every case required to exist simultaneously for a climb into the stratospheric waves, are not exceptional. The following list of requirements for record attempts was given in an article published in 2014:

  • Prefrontal conditions
  • Ridge top winds ≥ 40 knots
  • Winds within 30 degrees of perpendicular to ridgeline
  • Strong low-level winds
  • A stable atmosphere
  • A gradual wind increase in altitude
  • A weak tropopause

These conditions often occur during late winter and early spring over the southern Andes and Scandinavia. Flight testing started in Minden, NV in fall and winter of 2015, using a new hangar donated by Tito. The first attempts to reach 90,000 feet will be launched from El Calafate, Argentina, deep in the south of Patagonia, in the Southern Hemisphere soon afterwards in summer of 2016.<!--use month, as summer is January in South-->

Jim Payne (USA) and Morgan Sandercock (Australia) set a new altitude record of 15,902 metres (52,172 feet) from Comandante Armando Tola International Airport in El Calafate, Argentina. The flight took place on 3 September 2017.

The 2018 season was again based at El Calafate. The project acquired a Grob G 520 Egrett turboprop aircraft for use as a tow plane. This enabled Perlan II to be towed to This seems to be the highest glider tow, although such records are not registered.

thumb|Perlan II's list of actual and hoped-for records as of 2022

On 26 August 2018 Jim Payne and Morgan Sandercock reached an altitude of .

This was followed by with Jim Payne and Miguel Iturmendi on 28 August 2018.

Previous records were measured with pressure altitude; high altitude soaring records now require GPS data.

References

  • Perlan Project's official website
  • NASA Tech Brief DRC-00-08: Soaring to 100,000 ft on Stratospheric Mountain Waves