Max Q (Space Physics)

In aerospace engineering , Max Q denotes the point (in the spatial and temporal sense) at which the aerodynamic load on a flight object moving in areas with highly variable air density reaches its maximum. In addition to separating external tanks or rocket stages , Max Q is one of the critical times during a rocket launch.

The load is described by the dynamic pressure

${\displaystyle q={\frac {\rho }{2}}\,v^{2}}$

with the density ρ ("rho") and the speed v .

Application in space

After a rocket has been launched from the surface of the earth, the velocity v increases due to the acceleration , while the air density ρ decreases with increasing altitude. At a certain combination of speed and density, the dynamic pressure acting on the flying object is maximum, which corresponds to the point Max Q.

When the space shuttle took off , Max Q and thus the greatest load on the structure was reached after about one minute of flight at an altitude of about 11,000 m. When the moon rocket Saturn V was launched, Max Q was a little later at a higher altitude, with Apollo 8 this was at 13,400 m after 79 seconds , and the same two values ​​apply to the Falcon 9 from Space X. When the Apollo capsule re-entered, the maximum dynamic pressure was greater than when the Saturn V took off. In contrast, even with moderate dynamic pressure, the space shuttle generated sufficient aerodynamic lift to delay the descent into denser air masses.

Individual evidence

1. ↑ aerospaceweb.org: maximum Q and Dynamic Pressure
2. ↑ aerospaceweb.org: Space Shuttle Max-Q with graphics
3. ↑ Day 1: Launch and Ascent to Earth Orbit. (No longer available online.) In: Apollo Flight Journal (Apollo 8). NASA January 20, 2009; archived from the original on April 21, 2007 ; Retrieved on March 25, 2010 (English, with graphics): "1 minute, 18.9 seconds into the flight and 13,430 meters (44,062 feet) altitude, the stack reaches the point of maximum dynamic pressure, often called Max Q, where the interaction of these two phenomena has the largest effect on the vehicle's structure. It is usually considered a more dangerous time within the whole ascent " Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.