Something new to discuss ? (argue ).

76,000 feet in a glider

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Thanks for sharing this.
I didnt even know such a form of soaring is there.
Interesting to see the original site http://www.perlanproject.org

Cheers
Buwa

No comments on the typical, always misleading mainstream mass media though.

Video of the record flight:

Perlan 2 Highest Ever Soaring Flight Above 65,000 feet (2 min 5 sec)

Awesome achievement. Waiting for 90k feet goal.

Originally Posted by Davidz90

Awesome achievement. Waiting for 90k feet goal.

Would love to see them taking a photo of the bottom side of an SR-71

Andy

I think I saw an albatross go by

(kidding!)

Truly amazing

There I was at 7600 ft and a bird dog flew by————

Originally Posted by AndyKunz

Would love to see them taking a photo of the bottom side of an SR-71

Andy

The Perlan would have to also have the ability to travel in time....

Amazing. wonder how tight the airspeed range is at that altitude for those high aspect ratio wings.

Friend of mine that flew corporate jets said one of the things you have to learn is the tight window of speed you have to maintain at altitude, and it gets tighter the higher you are. one aircraft he flew he said only had something like a 20 knot window in IAS at the altitude they normally cruised at.

Originally Posted by GWRIGHT

Amazing. wonder how tight the airspeed range is at that altitude for those high aspect ratio wings.

Friend of mine that flew corporate jets said one of the things you have to learn is the tight window of speed you have to maintain at altitude, and it gets tighter the higher you are. one aircraft he flew he said only had something like a 20 knot window in IAS at the altitude they normally cruised at.

FYI this called the "Coffin Corner".

Coffin corner (also known as the aerodynamic ceiling or Q corner) is the region of flight where a fast fixed-wing aircraft's stall speed is near the critical Mach number, at a given gross weight and G-force loading (Wikipedia).

The U-2 also operates in a very limited flight envelope at high altitude.

Originally Posted by fnev

FYI this called the "Coffin Corner".

Coffin corner (also known as the aerodynamic ceiling or Q corner) is the region of flight where a fast fixed-wing aircraft's stall speed is near the critical Mach number, at a given gross weight and G-force loading (Wikipedia).

Passenger stuff commonly fly in this area

It is common for high altitude airplanes to have very little difference in indicated airspeed between stall and maximum airspeed/Mach number. In practice, this turns out not to be a huge deal. At 76,000 ft, 100 knots of indicated airspeed corresponds to 448 knots of true airspeed. 102 knots of indicated airspeed corresponds to 456 knots of true airspeed. The difference in kinetic energy between 100 and 102 knots therefore corresponds to a change in height of 312 ft. So in order to have a 2 knot indicated airspeed excursion, your altitude would have to change by more than 300 ft. At sea level, you’d only need to change altitude by 18 ft in order to see the same change in indicated airspeed. So while the available airspeed gets narrower, the task of staying inside that band gets easier. I had the chance to fly the Perlan simulator, and this effect was very apparent.

Yes, ShoeDLG, you are absolutely right. But this is an area where commercial pilots are not necessary well trained for (if getting in troubles). And to make things a bit more "interesting" this is where some airline companies want their pilots to fly as it saves fuel. Recently the Aeroflot pilots went on "strike" to remove incentives "forcing" them to fly in this part of the flight envelop for economic reasons.

The airfoil profiles seem to be closer to the shape that is utilized for RC scale rather than a full size sailplane. What average Reynolds number is the Perlan flying at at fl 760?

US and other airline companies hire from military ranks and those incoming pilots typically have experience in supersonic craft