What is the significance of Max Q in rocket launches and disasters?

In summary, the conversation discusses the Challenger disaster and the significance of maximum dynamic pressure, or MaxQ, during rocket launches. The report mentions that the space shuttle's maximum dynamic pressure is 720 pounds per square foot, which is equivalent to 5psi. This is significantly lower than the pressure of a typical car tire. The conversation also touches on the importance of accounting for MaxQ in the design of a rocket, considering the force it exerts on the spacecraft. While the MaxQ for an airplane is unknown, it is likely lower than that of a rocket. Overall, the conversation highlights the complexity and precision required in designing a spacecraft, given the extreme conditions it operates under.
  • #1
Devils
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17
So I was reading about the challenger disaster and came across this report:

http://history.nasa.gov/rogersrep/v1ch3.htm
Both the Shuttle main engines and the solid rockets operated at reduced thrust approaching and passing through the area of maximum dynamic pressure of 720 pounds per square foot.

I listed to rocket launches & they all seem to mention MaxQ but have never seen a value. From the report, 720 pounds per square foot = exactly 5psi. A typical car tyre is 30psi, so the maximum pressure on the space shuttle is about 1/6 of that of a car tyre.

That seems low to me so why mention it at all? The recent SpaceX was near Max Q so was that part of the problem, is was vibration the problem? What is Max Q for an airplane?
 
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  • #2
I don't know what I'm talking about, but just from a quick glance, a tire is small and the pressure is distributed nice and evenly, over a smooth profile. And if you make the tire 2-5 times stronger than it needs to be, well no big deal. On a space shuttle with an (educated guess) frontal area of 80000 in^2, that 5psi adds up to 400,000 lbs of extra force, squeezing it lengthwise along uneven paths and who knows what, designed to be juuuust strong enough, in a complex machine with a small nuke's worth of explosives. That's definitely something that should be accounted for in the rocket's design.
 
  • #3
I don't know what the maxQ of an aircraft is but pretty sure the VNE (Velocity Never Exceed) will be lower for a plane than a rocket perhaps by a factor of five?
 
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Related to What is the significance of Max Q in rocket launches and disasters?

1. What is Max Q and how does it relate to rocket disasters?

Max Q, or maximum dynamic pressure, is the point during a rocket's ascent where it experiences the most aerodynamic stress. This stress can cause structural damage or failures, potentially resulting in a rocket disaster.

2. What are some common causes of rocket disasters during Max Q?

Some common causes of rocket disasters during Max Q include structural failures due to high aerodynamic stress, engine malfunctions, and flight control issues.

3. How do scientists and engineers work to prevent rocket disasters during Max Q?

Scientists and engineers carefully design and test rockets to withstand high aerodynamic stress during Max Q. This includes using strong and durable materials, as well as implementing redundant systems to prevent failures.

4. Can Max Q be avoided during a rocket launch?

No, Max Q is a natural part of a rocket's ascent and cannot be avoided. However, scientists and engineers work to minimize the effects of Max Q to prevent disasters.

5. What happens if a rocket experiences a disaster during Max Q?

If a rocket experiences a disaster during Max Q, it may result in a catastrophic failure and loss of the rocket and its payload. In some cases, emergency systems may be able to mitigate the disaster and potentially save the rocket and its crew or payload.

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