MaxQ

MaxQ, sometimes written as Max-Q, is a term used in rocketry and aerospace to designate the point during atmospheric ascent when dynamic pressure on a vehicle reaches its maximum. Dynamic pressure, q, is defined as q = 0.5 × ρ × v², where ρ is atmospheric density and v is vehicle velocity. As a booster climbs, air density drops while speed increases, causing q to rise to a peak before decreasing in higher, thinner air.

The Max-Q event is significant because it represents the greatest structural and aerodynamic stress a vehicle experiences during ascent. Engineers design vehicles to withstand these loads, and flight controls often throttle engine power to limit forces around this point. Throttling down near Max-Q helps prevent excessive bending moments and structural damage, after which thrust is typically restored to maintain performance once the vehicle has passed through the peak dynamic pressure region.

Max-Q typically occurs within minutes after launch and is highly dependent on the vehicle's trajectory, propulsion profile, and atmospheric conditions. Launch teams monitor real-time telemetry to identify the peak and adjust flight parameters accordingly. The concept is a standard consideration in mission design and flight rules across both government launches and commercial programs.

See also: aerospace engineering, dynamic pressure, rocket ascent, throttling strategy.