1
$\begingroup$

What is the maximum altitude a manned plane that flies subsonically can reach? Subsonic airplanes can't go as high as super- and hypersonic ones of course, so record holders are the latter ones. But ironically, the altitude record for leveled flight is set by the subsonic NASA Helios propeller aircraft at ~97,000 ft. However that's an uncrewed and weird-looking one. Can manned airplanes that fly subsonically go above the Armstrong line (60-63,000 ft) and higher (either in leveled or in parabolic flight), considering realistic fuel limitations? How high can subsonic airplanes go compared to supersonic ones?

$\endgroup$
0

1 Answer 1

3
$\begingroup$

76,000 feet. Airbus Perlan Mission II glider, Sept 2, 2018. (If Airbus keeps changing their press releases' URLs, see also Wikipedia.)

The U-2 has a higher service ceiling, 80,000 feet, but it hasn't reached that. (Perlan II's service ceiling is 90,000 feet.)

$\endgroup$
17
  • 1
    $\begingroup$ @Giovanni a glider is a plane, and it is both manned and subsonic, thus fulfilling all your criterias set in the question, no? $\endgroup$
    – Federico
    Dec 15, 2020 at 16:58
  • 4
    $\begingroup$ @Giovanni: If it was brought to that altitude by another plane, then that plane could obviously fly to that altitude. But it wasn't: it's a sailplane: it's released at low altitude and uses wave lift to climb. Likewise, you could put someone in a pressure suit aboard a Helios-like craft. And then there's NASA's Mars helicopter: mars.nasa.gov/technology/helicopter $\endgroup$
    – jamesqf
    Dec 15, 2020 at 17:34
  • 2
    $\begingroup$ @Giovanni: Gliders & propellor airplanes do not use buoyancy. Balloons use buoyancy. Per Wikipedia, the record for an unmanned balloon is 173K ft, manned a bit over 135K. WRT the Mars helicopter, the point is that if a rotorcraft can work at such low atmospheric pressure, then prop planes should. And WRT jets, I think at very high altitude you'd need either a rocket or an electric motor - but I defer to anyone with more knowledge. $\endgroup$
    – jamesqf
    Dec 15, 2020 at 23:59
  • 1
    $\begingroup$ @Giovanni: Buoyance is when an object weighs less than the material it's immersed in. Balloons weigh less than the surrounding air, so they go up until they reach equilibrium. (Likewise ships displace an amount of water equal to their weight.) Gliders climb by means of lift: they get into a bit of air that's rising, and climb along with it. The lift can be from wind blowing up a slope (as with hang gliders on the coast), from thermals (most common with sailplanes), or mountain waves, which (as with the Perlan) can take you really high when conditions are right. $\endgroup$
    – jamesqf
    Dec 17, 2020 at 2:28
  • 4
    $\begingroup$ @Giovanni: To be clear, a glider is always going down relative to the surrounding air (ignoring maneuvers where you trade off speed & altitude: that's a net zero). It's just that you can find masses of air that go up faster than the glider goes down. $\endgroup$
    – jamesqf
    Dec 17, 2020 at 2:32

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .