A Glider at 76,,000ft!

[sharpy1071]

How on earth did the Airbus Perian II get to 76,000ft? It is designed to go to 90,000ft, it got to 76,000ft this week. Are there thermals to that height? who will build the first RC model of this glider.

 

Edited By sharpy1071 on 08/09/2018 19:49:15

Edited By sharpy1071 on 08/09/2018 19:50:26

[Malcolm Fisher]

I tried to bring this to Forumites attention using the Gliders and Gliding topic. I subscribe to New Atlas which brings details of all sorts of developments. IIRC the Perlan was reported as using updrafts created when strong winds hit each other and mountains. The flight was over the Andes and was reported as an altitude greater than that reached by the X5.

Malcolm

[Martin Harris - Moderator]

This explanation gives details of how wave lift and related effects can give lift above the tropopause (@30 000 feet at the Poles to 56 000 feet at the equator):

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.^[4] This method uses the powerfully rising and sinking air in mountain waves. Gliders regularly climb in these waves to high altitudes.

Prior to the September 4th, 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.^[5] 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.