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The Perlan high altitide glider project has the following stats

enter image description here

This suggests that a glider / high altitude airliner could be economically viable and save a lot on fuel at 60000ft.

I realize this is not a complete picture, but it seems compelling. How to fully analyze this? Please list steps.

There have been a number of military gliders that are large https://en.m.wikipedia.org/wiki/Military_glider

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  • $\begingroup$ @ralph j. This is not homework. Is self assigned. $\endgroup$
    – Smith
    Feb 4, 2018 at 17:38
  • $\begingroup$ Because gliders are slow, and the appeal of commercial air travel is crossing the country in 4 hours. $\endgroup$
    – abelenky
    Feb 4, 2018 at 18:24
  • $\begingroup$ "crossing the country in 4 hours". Well that's not a very difficult goal to achieve for most of the world :-) We just need to slow down a bit. $\endgroup$
    – mins
    Feb 4, 2018 at 18:48
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    $\begingroup$ The graph says Vne at FL300 to FL400 is 200 to 250 kts while airlines easily do 500-600 kts. That does not look fast to me. $\endgroup$
    – abelenky
    Feb 4, 2018 at 20:43
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    $\begingroup$ They are powered gliders. They are just much better at the "powered" part than at the "gliding" part. $\endgroup$
    – Jörg W Mittag
    Feb 5, 2018 at 7:13

1 Answer 1

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Why aren’t airliners gliders? Because it takes lots of power to move a hundred or so people across the country and gliders are by definition unpowered.

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  • $\begingroup$ Powered gliders exist. Also with a much longer glide distance aka lower wind resistance. $\endgroup$
    – Smith
    Feb 4, 2018 at 17:35
  • $\begingroup$ @mins airliners have a glide ratio much lower than that defined for gliders. $\endgroup$
    – Smith
    Feb 4, 2018 at 18:03
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    $\begingroup$ @JosephHobbs: Yes, as I wrote... they are optimized to lift 200 tons and fly at Mach .82. Else they are able to glide very well. $\endgroup$
    – mins
    Feb 4, 2018 at 18:07

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