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55 votes

Why aren't rockets built with truss structures inside their fuel & oxidizer tanks to increase structural strength?

There's almost nothing to be gained by a truss. The load being applied is along the axis of the tank. A simple hoop of material is very strong in this orientation. (Try it with a piece of paper, ...
Loren Pechtel's user avatar
32 votes

Why aren't rockets built with truss structures inside their fuel & oxidizer tanks to increase structural strength?

Because they don't need to be. Clearly the current design of rockets can be successful. So adding truss structures to the current design would add weight for no reason and take away from the payload ...
Organic Marble's user avatar
19 votes

Why aren't rockets built with truss structures inside their fuel & oxidizer tanks to increase structural strength?

Most modern rockets do rely to some extent on tank pressure for strength. The tankage needs to be pressurized in any case to drive the turbopumps without risk of cavitation, so the structural strength ...
Russell Borogove's user avatar
18 votes

Could one survive a ride into orbit outside a rocket?

Partial answer Max q may not be a problem, at least not a fatal problem. Colonel John Stapp survived (albeit with injuries) being exposed to a dynamic pressure of about 1200 lbf / ft^2 in the Sonic ...
Organic Marble's user avatar
13 votes

Why aren't rockets built with truss structures inside their fuel & oxidizer tanks to increase structural strength?

Because it would be an inefficient way to handle the loads. Let's say your rocket is a simple cylinder with engines at the bottom (no strap-on boosters or fins that might actually need extra ...
TooTea's user avatar
  • 1,765
12 votes
Accepted

What percentage of overall fuel does a rocket burn up to get to max-q?

would the percentages of fuels for different rockets at max-q vary? Yes, it will certainly vary with different rocket designs, and even for a given launcher with different payloads and trajectories. ...
Russell Borogove's user avatar
11 votes

Has Max-Q historically been a common failure point in rocket launches?

Both of the shuttle flights that suffered fatal accidents encountered significant wind shear events that took place very close to max q. I'm not aware that this was directly linked to the accidents ...
Organic Marble's user avatar
10 votes

Does MAX Q during rocket launch only say that rocket experiences max dynamic pressure?

Generally no, max Q is typically well above mach 1. (I think there’s another question about this on the site.) Dynamic pressure is proportional to velocity squared, so speed rather than drag ...
Russell Borogove's user avatar
9 votes

Has Max-Q historically been a common failure point in rocket launches?

Rockets usually fail early in flight, within a minute of liftoff, or in the vacuum stage since that is hard to simulate on Earth. You can see a list of rocket failures here. The structure is one of ...
Liu's user avatar
  • 107
8 votes

Would max-Q coincide with the loudest/roughest part of the flight?

While I'm not sure if loudness correlates well with roughness, I did find a study that correlates roughness (vibrations) with Max-Q. The study describes the source of roughness as thrust oscillations, ...
phil1008's user avatar
  • 6,221
7 votes

What will Max Q for descent be?

According to https://www.flightclub.io/results/?code=SS10 , reentry Q for flights like SES-10 peak at almost 92kPa at T+434 sec, about 3x the ascent max Q. The reentry prep burn brings velocity down ...
Russell Borogove's user avatar
7 votes

Has Max-Q historically been a common failure point in rocket launches?

The uncrewed Mercury-Atlas 1 flight suffered a catastrophic failure due to aerodynamic loads at or near max-Q, and the launcher's structure was beefed up for future flights: [NASA's Owen Maynard] ...
Russell Borogove's user avatar
6 votes

Why making such a big deal with Max Q?

Then why making such a big deal with this first Max Q which is by far, less important compared to the second one? Calling out Max Q is a tradition. The overwhelming majority of vehicles that launch ...
Jörg W Mittag's user avatar
6 votes

What was the actual Q-alpha limit for Saturn/Apollo launches, and what was the typical max Q-alpha?

I have not yet found the abort limit figure. According to Saturn V AS-507 "G" Mission Launch Vehicle Operational Flight Trajectory - September Launch Month (a trajectory planning document for Apollo ...
Russell Borogove's user avatar
5 votes
Accepted

Why the max dynamic pressure might not happen at maximum drag instant?

Wikipedia's Drag equation is $$F_D = \frac{1}{2} \rho v^2 C_D A$$ shows drag's $\frac{1}{2} \rho v^2$ dependence you mention, as does @MarkAdler's answer about dynamic pressure or "Q": Max ...
uhoh's user avatar
  • 149k
4 votes
Accepted

Just how much can tall skinny rockets bend? (roughly, safely)

Nothing can be perfectly inflexible without causing undue stress on the hold downs. Similar to using a longer crowbar to gain leverage making any wind load transfer directly to the hold-down clamps, ...
Daryl Morning's user avatar
4 votes
Accepted

How is max Q for the shuttle actually defined?

Max Q is simply the maximum of the dynamic pressure of the external flow, ${1\over 2}\rho v^2$. It has nothing to do with the vehicle, except for the vehicle's speed relative to the undisturbed fluid.
Mark Adler's user avatar
  • 58.2k
4 votes

Is it possible to calculate Max-Q without having to input an altitude

I'm not sure I understand the question completely, but I'll work off of the comment Of course the faster you go, the faster you reach max-q. So you must be able to say "by going this fast, you will ...
uhoh's user avatar
  • 149k
4 votes

Falcon 9 Max Q on reentry?

According to a simulation at FlightClub.io, aerodynamic pressure for the first stage reentry peaks at about 112 kPa.
Russell Borogove's user avatar
4 votes

Could one survive a ride into orbit outside a rocket?

Main problem will be deadly sound blast that most big rockets generate. 150 decibels is enough to burst your eardrums, 185-200 dB is enough to kill you. Space Shuttle was about 180 dB at launch site, ...
David Cage's user avatar
4 votes

Why aren't rockets built with truss structures inside their fuel & oxidizer tanks to increase structural strength?

I worked on the Atlas rockets which had pressurized tanks (balloon tanks) for structural rigidity/strength. For transport, the Atlas went into a truss to hold the rocket in tension to keep it from ...
ThomasAHawk's user avatar
4 votes

What was the actual Q-alpha limit for Saturn/Apollo launches, and what was the typical max Q-alpha?

Edit: I stumbled upon the limit. The maximum angle-of-attack dynamic pressure sensed by a redundant Q-ball mounted atop the escape tower was 0.28 N/cm2 (0.4 psid) between 89 and 91 seconds. This ...
Organic Marble's user avatar
3 votes

When did the Astra Space test flight 006 actually reach max-Q? There is substantial disagreement in the audio feed of the launch (Launch Vehicle 0006)

Dynamic pressure is straightforward to calculate: $$q = \tfrac12\, \rho\, v^{2}$$ Where $\rho$ is the density of the air and $v$ is velocity. Using the available onscreen velocity and altitude figures,...
Russell Borogove's user avatar
1 vote

Falcon 9 Max Q on reentry?

This is not directly related, but here's a graph from measurements of Apollo. From NASA tech report 19690029435 The report includes this graph of dynamic pressure as the Apollo capsule returned to ...
Carl Witthoft's user avatar
1 vote

Has Max-Q historically been a common failure point in rocket launches?

It's not so much that the max-Q point itself is dangerous, the vehicle acceleration is managed to keep aerodynamic forces to levels that shouldn't be a problem. However, it is the most aerodynamically ...
Christopher James Huff's user avatar

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