On Wednesday, August 15, 2018 at 10:13:37 PM UTC-5, Ramy wrote:
Typo aside, am I the only one somewhat disappointed to learn that the plan is to tow the Perlan to 50,000 feet, or I missread the article? I was kind of hoping the Perlan is capable of climbing to 90K from a reasonable tow altitude.

Ramy

What, Real Men scratch around for hours just to prove ...what?...
The fact is that Perlan was designed to fly in and study *stratospheric* wave, not tropospheric wave. These waves are rarely stacked and connected. Perlan I found such linked wave once in two years, and then set a record over 50,000 ft. Perlan II found such linked wave once in two years, and then set a record over 50,000 ft.

The hope is to do aerodynamic and atmospheric research in the stratosphere. In the winter, the tropopause (the boundary between tropo- and strato-sphere) generally descends to about 30,000 msl. It happens to be about 40,000 msl in the southern hemisphere at the moment.

The Egrett, used as a towplane, is able to reliably bring Perlan II into the lower reaches of the stratosphere in about an hour. Only in this way will the glider be a reliable research vehicle.

And such research is important: the polar night jets are poorly understood, yet are known to drive climate in some ways. It is not know what triggers stratospheric wave, and one of the hindrances to Perlan "success" is that predictive models are inaccurate simply because of human ignorance.

While it's spectacular to set altitude records, the real importance of this project is making steps toward stratospheric research in a vehicle that will not contaminate the nearby atmosphere with noise: chemical, mechanical, aerodynamic.

This is not a toy and its mission is not play.
DrDan Johnson