When a rocket launches, it accelerates, and thus experiences atmospheric drag as it punches through the air; the faster, the more resistance.
After a few minutes, the air is so thin the resistance decreases, until the Karmann Line, where you’re in “space” and thus no more air resistance.
The maximum air resistance is known as "Max Q’'.
I figure, there is a max q for re-entry as well, yes?
Or does it have a different nomenclature?
Timely thread, because I just finished reading (or actually, skimming) a book about how the space shuttle flew:
Despite my interest in the subject, the book is so detailed I didn’t read it word for word. Apparently the shuttle’s re-entry was complicated by its relatively unusual shape (compared to a capsule), and consisted of several phases and sub-phases. You can borrow the book from the Internet Archive link above.
I don’t have an answer, but here’s a data point (that you probably already know):
The people who have jumped from over 100K feet (Kittinger et al.) accelerated for (maybe 1/3?) of the distance before they started slowing down due to higher drag. That’s a lot different from orbit, but hey, it’s a free bump.
Technically, max Q is the point of maximum dynamic pressure. Where that will occur depends upon how fast the launch vehicle is moving at a given altitude. For performing coupled loads analysis and aeroloading, we are actually concerned with the product of dynamic pressure and angle of attack, or “max Q-alpha”.
There is also a max-Q point upon reentry; however, for a returning spacecraft it is less critical from a controls standpoint because there is no thrust, and most reentry vehicles are much more compact and stiffer than rocket launch vehicles, and they are typically designed to be stable (or at least within broad bounds of stability) during reentry. In terms of dynamic pressure, for vehicles which use aerodynamic decelerators such as parachutes or ballutes, the concern is the dynamic pressure they experience during deployment such that it does not produce internal forces and stresses which would rupture the materials.
The biggest concern upon reentry is, of course, aerodynamic heating which despite often being incorrectly referred to as “skin friction” is actually actually due to compression of the air in front of the vehicle at the shockwave boundary, and the successive thermal radiation from that highly compressed air. This occurs much higher in the atmosphere and is the reason that there is a need for heat shields, tiles, and thermal blankets to protect critical vehicle structure and systems.
Stranger
To add to @Stranger_On_A_Train 's answer, yes, you definitely have a max Q during re-entry.
The problem for the reentry vehicle designer is often to spread out the forces of reentry (and corresponding parameters like heating) over a longer time, to reduce the maximum g forces experienced by the crew and cargo. One way to do this is to design vehicles that can generate some lift during re-entry, not just drag, to help reduce the rate of descent and stay in a “nice” altitude for re-entry for longer. Then, the vehicle can decelerate gently but over a longer distance and time, resulting in a less stressful ride.
The space shuttle can do this, but so can capsules, such as Apollo, Soyuz, Dragon, etc. The space shuttle typically experienced about ~ 2 g’s or less during re-entry, and for about 10 minutes. Contrast this with Soyuz, in “ballistic” mode, which in one case subjected the astronauts to about 8 g’s for one minute.
Long story short, you get a max Q, regardless, the question is how big is it. It can be managed.
On a related note, here’s a good video from Scott Manley explaining why it’s just not practical for spacecraft to avoid the searing heat of reentry (12 minutes):
