Max Q
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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: q = ρv2 / 2, we have that such quantity:
- is zero at lift-off, when the vehicle's speed v = 0
- is zero outside the atmosphere, where the air density ρ = 0
- is always positive (or zero, as above) given the quantities involved
Therefore there will be necessarily 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 ft - 46,000 ft).[2][3]
[edit] See also
[edit] Notes
- ^ 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.
