In aerospace engineering, max Q is the point of maximum dynamic pressure, the point at which aerodynamic stress on a spacecraft in atmospheric flight is maximized. Considering the definition of dynamic pressure: <math>q=\rho v^2 / 2</math>, we have that such quantity:
- is zero at lift-off, when the vehicle's speed <math>v=0</math>
- is zero outside the atmosphere, where the air density <math>\rho=0</math>
- is always positive (or zero, as above) given the quantities involved
Therefore, there will necessarily be a point where the dynamic pressure is maximum: that point is precisely max Q. In other words, below the max Q point, the effect of the spacecraft acceleration overcomes the decrease in density. Above the max Q point, the opposite is true. During a normal Space Shuttle launch, for example, max Q is at an altitude of around 11 km (35,000 ft).[1] During a typical Apollo mission, max Q occurred approximately between 13 km and 14 km of altitude (43,000–46,000 ft).[2][3]
See also
References
- ^ Jackson, Douglas T. (2001-05-06). Space Shuttle Max-Q. Aerodynamics Questions. AerospaceWeb.org. Retrieved on 2007-02-12.
- ^ Woods, David; O'Brien, Frank (2005-08-21). Apollo 8, Day 1: Launch and Ascent to Earth Orbit. Apollo Flight Journal. NASA. Retrieved on 2007-02-14.
- ^ Brandt, Tim; Woods, David (2004-10-29). Apollo 16, Day One Part One: Launch and Reaching Earth Orbit. Apollo Flight Journal. NASA. Retrieved on 2007-02-14.
