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When, hopefully, Virgin Galactic spacecraft start regular operations in a few years, they will be simply travelling upwards, then achieving weightlessness for a short while, followed by a return straight back down, as they cannot carry anything approaching enough fuel to achieve orbit.

enter image description here

So they are basically recreating Alan Shepard's flight from 55 years ago, travelling up and down, rather than around and around.

On the other hand, when NASA achieved flights to the moon, their Apollo spacecraft velocity was such that their reentry angles had to stay within certain limits. If they were too steep, they would burn up, if they were too shallow they would skip/bounce off the Earth's atmosphere and back into space.

enter image description here

My question is, bearing in mind the density of air versus altitude in the picture above, is it possible for a suborbital flight to attain a velocity sufficient to allow the vehicle to achieve a skip and then descend, so as to achieve a significant distance?

Unfortunately, this chart is not detailed enough to show anything but effectively zero air density, even at 50 km, around 20 km less than a suborbital flight.

I would not be asking this question if I knew enough fluid dynamics to calculate it myself, but in specific terms, is there an equation from fluid dynamics that covers this idea? Obviously, velocity and air resistance/ density are crucial, but I would assume a velocity of 3000 to 5000 kph, using rockets.

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    $\begingroup$ en.wikipedia.org/wiki/Silbervogel $\endgroup$
    – user56903
    Commented Sep 15, 2016 at 13:10
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    $\begingroup$ @DirkBruere thank you very much, it's not nice thinking of the same idea that that bunch came up with 70 years ago, though.....but swords to ploughshares . I am sure Branson has thought of it though. $\endgroup$
    – user108787
    Commented Sep 15, 2016 at 13:31
  • $\begingroup$ When Apollo returned from the moon, it was traveling at about escape velocity, which was much higher than orbital velocity. The danger was if they "skipped" they would only slow down below escape velocity, and thus go into orbit (with no way to get down). So they had to pick an angle between a) skipping, and b) smashing into the lower atmosphere. Any skip slows it down, so no skip with lengthen a suborbital flight. $\endgroup$
    – Mike Dunlavey
    Commented Sep 15, 2016 at 15:25
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    $\begingroup$ @MikeDunlavey Wikipedia says, FWIW it was to climb to 145 km , travelling at 5,000 km/h. It would then gradually descend into the stratosphere, where the increasing density generated lift against the flat underside of the aircraft, eventually causing it to bounce and gain altitude again, the pattern would be repeated. Due to drag, each bounce would be shallower than last. I take your point 100%, and I don't want to take up your time , this is what I should have written instead, going up rather than coming down (if it works in 1st place) en.wikipedia.org/wiki/Silbervogel $\endgroup$
    – user108787
    Commented Sep 15, 2016 at 17:16

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