What altitude would the LES (launch escape subsystem) reach on Apollo launches before falling back to Earth?


According to this article about duplicating a Saturn V/Apollo trajectory in simulation, the LES is jettisoned at 198 seconds into the flight, at which time altitude is just under 100km and vertical speed is about 650m/s (very rough numbers obtained by eyeballing those graphs).

If we disregard the (very brief) acceleration from the jettison motor, and ignore atmospheric drag (negligible at this altitude, as PearsonArtPhoto points out), a pure ballistic trajectory from that point would make it top out at about 120km.

(Okay, so my initial estimate was completely horrible.)

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    $\begingroup$ Don't forget the stage is moving about 2.5 km/s at that point in time, which will give it considerable altitude. Of course, most of that is horizontal velocity, and which part is which is a bit tricky to determine, but... $\endgroup$ – PearsonArtPhoto Oct 16 '14 at 14:05
  • $\begingroup$ Yeah, it could be a bit higher, but if it's the pitchover motor used to get it out of the way, with no CM attached, it's going to be spinning like a baton, and I think it'll slow down very rapidly. $\endgroup$ – Russell Borogove Oct 16 '14 at 15:58
  • $\begingroup$ Hm, actually the jettison motor is separate from both the pitchover and escape motors, and looks like it has two symmetrical nozzles. So it may very well fly stably and get a lot higher. $\endgroup$ – Russell Borogove Oct 16 '14 at 16:13
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    $\begingroup$ Spinning won't significantly slow it down at the listed altitude. $\endgroup$ – PearsonArtPhoto Oct 16 '14 at 16:14
  • $\begingroup$ facepalm Oh, of course. I'm an idiot. $\endgroup$ – Russell Borogove Oct 16 '14 at 16:15

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