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# Coffin corner (aerodynamics)

Coffin corner (also known as the aerodynamic ceiling or Q corner) is the region of flight where a fast fixed-wing aircraft's stall speed is near the critical Mach number, at a given gross weight and G-force loading. [1]

## Airspeed

Airspeed is the speed of an aircraft relative to the air.

## Altitude

Altitude or height (sometimes known as depth) is defined based on the context in which it is used (aviation, geometry, geographical survey, sport, atmospheric pressure, and many more).

## Angle of attack

In fluid dynamics, angle of attack (AOA, or \alpha (Greek letter alpha)) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is moving.

## Center of pressure (fluid mechanics)

The center of pressure is the point where the total sum of a pressure field acts on a body, causing a force to act through that point.

## Critical Mach number

In aerodynamics, the critical Mach number (Mcr or M*) of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it.

## Density of air

The density of air ρ (Greek: rho) (air density) is the mass per unit volume of Earth's atmosphere.

## Drag (physics)

In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.

## Drag divergence Mach number

The drag divergence Mach number (not to be confused with critical Mach number) is the Mach number at which the aerodynamic drag on an airfoil or airframe begins to increase rapidly as the Mach number continues to increase.

The Federal Aviation Administration (FAA) of the United States is a national authority with powers to regulate all aspects of civil aviation.

## Fixed-wing aircraft

A fixed-wing aircraft is an aircraft, such as an airplane or aeroplane (note the two different spellings), which is capable of flight using wings that generate lift caused by the vehicle's forward airspeed and the shape of the wings.

## Flight envelope

In aerodynamics, the flight envelope, service envelope, or performance envelope of an aircraft or interplanetary spacecraft refers to the capabilities of a design in terms of airspeed and load factor or atmospheric density, often simplified to altitude for Earth-borne aircraft.

## Flow separation

All solid objects traveling through a fluid (or alternatively a stationary object exposed to a moving fluid) acquire a boundary layer of fluid around them where viscous forces occur in the layer of fluid close to the solid surface.

## G-force

The gravitational force, or more commonly, g-force, is a measurement of the type of acceleration that causes a perception of weight.

## Helicopter

A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors.

## Helicopter height–velocity diagram

The height–velocity diagram or H/V curve is a graph charting the safe/unsafe flight profiles relevant to a specific helicopter.

## Indicated airspeed

Indicated airspeed (IAS) is the airspeed read directly from the airspeed indicator (ASI) on an aircraft, driven by the pitot-static system.

## International Standard Atmosphere

The International Standard Atmosphere (ISA) is an atmospheric model of how the pressure, temperature, density, and viscosity of the Earth's atmosphere change over a wide range of altitudes or elevations.

## Lift (force)

A fluid flowing past the surface of a body exerts a force on it.

In aeronautics, the load factor is defined as the ratio of the lift of an aircraft to its weightHurt, page 37 and represents a global measure of the stress ("load") to which the structure of the aircraft is subjected: where: Since the load factor is the ratio of two forces, it is dimensionless.

## Lockheed U-2

The Lockheed U-2, nicknamed "Dragon Lady", is an American single-jet engine, ultra-high altitude reconnaissance aircraft operated by the United States Air Force (USAF) and previously flown by the Central Intelligence Agency (CIA).

## Mach number

In fluid dynamics, the Mach number (M or Ma) is a dimensionless quantity representing the ratio of flow velocity past a boundary to the local speed of sound.

## Mach tuck

Mach tuck is an aerodynamic effect whereby the nose of an aircraft tends to pitch downward as the airflow around the wing reaches supersonic speeds; the aircraft will first experience this effect at significantly below Mach 1.

## Machmeter

A Machmeter is an aircraft pitot-static system flight instrument that shows the ratio of the true airspeed to the speed of sound, a dimensionless quantity called Mach number.

## Moment (physics)

In physics, a moment is an expression involving the product of a distance and a physical quantity, and in this way it accounts for how the physical quantity is located or arranged.

## Shock wave

In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance.

## Speed of sound

The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium.

## Stall (fluid mechanics)

In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases.

## Statics

Statics is the branch of mechanics that is concerned with the analysis of loads (force and torque, or "moment") acting on physical systems that do not experience an acceleration (a.

## Structural integrity and failure

Structural integrity and failure is an aspect of engineering which deals with the ability of a structure to support a designed load (weight, force, etc...) without breaking, and includes the study of past structural failures in order to prevent failures in future designs.

## Tailplane

A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplanes.

## Thrust

Thrust is a reaction force described quantitatively by Newton's third law.

## Tropopause

The tropopause is the boundary in the Earth's atmosphere between the troposphere and the stratosphere.

## True airspeed

The true airspeed (TAS; also KTAS, for knots true airspeed) of an aircraft is the speed of the aircraft relative to the airmass in which it is flying.

## Turbulence

In fluid dynamics, turbulence or turbulent flow is any pattern of fluid motion characterized by chaotic changes in pressure and flow velocity.

## United States

The United States of America (USA), commonly known as the United States (U.S.) or America, is a federal republic composed of 50 states, a federal district, five major self-governing territories, and various possessions.

## Weight

In science and engineering, the weight of an object is related to the amount of force acting on the object, either due to gravity or to a reaction force that holds it in place.

## References

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