Talk:2087: Rocket Launch

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I had to fight the urge to type Care Bare Arachrah (talk)

This was published during the Arianespace launch livestream, between launch and satellite deployment: Fabian42 (talk) 17:11, 19 December 2018 (UTC)

Looks like it could be an Ariane5 in the comic, it is a 3 stage. Anyone know if Max-CB is a real thing (and before I get any wisecracks, I know there aren't any Care Bears in the clouds) 20:27, 19 December 2018 (UTC)

A search for rocketry terminology reveals that Cb stands for Ballistic Coefficient, which is a measure of the ability to coast. It is related to both velocity and air density, which vary throughout a rocket launch, so it makes sense that there might be some point of maximum ballistic coefficient. (Note: I am not a rocket scientist, and this is clearly rocket science, so take this with a grain of salt!) Ianrbibtitlht (talk) 21:13, 19 December 2018 (UTC)
That point is called "Max-Q". Source: I've seen a lot of rocket launches recently and they always mention it, because it's the second most likely moment to have a failure (first is the launch, of course). Fabian42 (talk) 07:28, 20 December 2018 (UTC)
Pontificating further, it is reasonable to conjecture that as a rocket accelerates to higher speeds, the drag from the atmosphere increases with increasing speed, but past a certain point the drag begins to decrease as the air gets thinner. This suggests there is some point somewhere during the launch sequence where aerodynamic drag reaches a maximum value - aka Max Cb. Ianrbibtitlht (talk) 21:26, 19 December 2018 (UTC)
Finally one I can help with! Okay, I don't think this is ballistic coefficient for several reasons: 1. Ballistic Coefficient is typically noted by the greek letter Beta, not Cb. 2. Ballistic coefficient is mass divided by drag area (drag coefficient times reference area). Basically a shape parameter. So while the mass does change over the course of the flight (burning fuel), the drag area does not. Making this a somewhat useless parameter for a launch vehicle 3. Ballistic Coefficient is typically reported as a static parameter rather than a time-varying parameter, so "Max ballistic coefficient" is a rather unusual metric (and would occur on the launch pad in any case, when mass is highest). Finally, as an aside, objects with high ballistic coefficients tend to fly through the air easily and are not influenced very much by wind (such as rocks or bullets), whereas low-beta objects can by pushed and slowed down a lot by the wind (such as balloons). Tyanderson91 (talk) 03:17, 20 December 2018 (UTC)

r/shittyspacexideas -- 19:53, 19 December 2018 (UTC)

If you trace the dotted lines, it seems that the Boosters are the winnersCCCVVVA (talk) 03:02, 20 December 2018 (UTC)

This was posted on the day SpaceX was supposed to launch the GPS-III-2 satellite, which may be the reason for the mention of GPS Tyanderson91 (talk)

The max CB is clearly meant to spoof the real problem of rockets hitting birds. Since birds can't fly in the he upper part of the atmosphere, the point of highest likelihood of hitting a bird would presumably be below max-Q and not above it as in the comic. It is worth noting that there are no clouds at the altitude where max CB is shown in the comic, so it seems unlikely that any hypothetical cloud castle would be that high.

EDIT: ok, after checking the numbers it seems like it is technically possible to encounter birds and clouds at heights above max-Q for some rockets, but the position shown in the comic still seems too high. Probably not Douglas Hofstadter (talk) 04:23, 20 December 2018 (UTC)

I suspect "pursuit phase" refers either to predation or to some aspect of air warfare (either involving missiles chasing craft or craft vs. craft). Magic9mushroom (talk) 08:08, 20 December 2018 (UTC)