Flight Airspeed and Atmosphere

Aeronautical data elements based on the 1976 US Standard Atmosphere

Available for these objects: Aircraft, LaunchVehicle, Missile

Type: Time-varying data. Intended to be used only with elements from this same data provider. Supports Temperature for use with EOIR.

Availability: Reports | Graphs | Dynamic Displays | Strip Charts

Data Provider Elements

Name	Dimension	Type	Description
Time	Date	Real Number or Text	Time from start of vehicle epoch.
MSL Altitude	AviatorAltitude	Real Number	Altitude relative to mean sea level.
True Air Speed	AviatorSpeed	Real Number	The magnitude of the velocity of the vehicle, where the velocity is measured as observed from the vehicle's central body fixed coordinate system.
Cal Air Speed	AviatorSpeed	Real Number	CAS is the airspeed that would be measured by a perfect pitot static system that uses the difference between total pressure and static pressure. It differs from EAS in that a pitot static system is affected by compressibility of air at higher speeds as well as shocks at supersonic speeds. CAS can be directly measured on an aircraft using a pitot static system.
Equiv Air Speed	AviatorSpeed	Real Number	EAS - the airspeed at sea level in the International Standard Atmosphere at which the dynamic pressure is the same as the dynamic pressure at the true airspeed (TAS) and altitude at which the aircraft is flying. EAS = TAS * sqrt(rho at altitude / rho at sea level). Since there is no easy way to directly measure TAS or density, the calculation of EAS is usually implemented in air data computers in modern aircraft using CAS and other data inputs.
Mach #	Unitless	Real Number	Speed / SpeedOfSound.
Dynamic Pressure	Pressure	Real Number	0.5 * rho * TAS^2
Static Temperature	Temperature	Real Number	A measure of internal energy (heat and molecular activity) in a fluid, separate from the velocity of the fluid.
Total Temperature	Temperature	Real Number	In thermodynamics and fluid mechanics, stagnation temperature is the temperature at a stagnation point in a fluid flow. At a stagnation point the speed of the fluid is zero and all of the kinetic energy has been converted to internal energy. In both compressible and incompressible fluid flow, the total temperature is constant at all points on the streamline.
Static Pressure	Pressure	Real Number	Every point in a steadily flowing fluid, regardless of the fluid speed at that point, has its own static pressure P, dynamic pressure q, and total pressure P0. Static pressure and dynamic pressure are likely to vary significantly throughout the fluid but total pressure is constant along each streamline.
Total Pressure	Pressure	Real Number	Every point in a steadily flowing fluid, regardless of the fluid speed at that point, has its own static pressure P, dynamic pressure q, and total pressure P0. Static pressure and dynamic pressure are likely to vary significantly throughout the fluid but total pressure is constant along each streamline.
Density	Density	Real Number	Atmospheric density - mass per volume
Dynamic Viscosity	DynamicViscosity	Real Number	The dynamic (or absolute) viscosity of a fluid (mu) is a measure of its resistance to deformation at a given rate. Viscosity can be conceptualized as quantifying the internal frictional force that arises between adjacent layers of fluid that are in relative motion, and has units force X time/area.
Kinematic Viscosity	KinematicViscosity	Real Number	In fluid dynamics, it is common to work in terms of the kinematic viscosity (also called "momentum diffusivity"), defined as the ratio of the viscosity μ to the density of the fluid ρ. It is usually denoted by the Greek letter nu (ν) and has dimension length^2 / time.
Reynolds Number per meter	Unitless	Real Number	The Reynolds number (Re) helps predict flow patterns in different fluid flow situations. At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers flows tend to be turbulent. The Reynolds number is a primary driver of aerodynamic effects and is a critical value involved in modeling the aerodynamics of a vehicle. The value presented is normalized to a vehicle length of 1 meter, vehicles of different lengths would multiply the Re value by actual length. Re = TAS * Length / nu.
Reynolds Number - Log10	Unitless	Real Number	The logarithm base 10 of Re. Re spans a very large range from small fish (Re ~ 1) to ocean liners (Re ~ 10^9). The boundary between smooth laminar flow and turbulent flow varies, but is generally in the range of Re ~ 10^3 - 10^6.
Normal Shock Downstream Mach #	Unitless	Real Number	The value of Mach # behind a normal shock - will always be less than 1.
Normal Shock Downstream Static Temperature	Temperature	Real Number	The value of static temperature behind a normal shock - static temperature increases behind shocks.
Normal Shock Downstream Total Temperature	Temperature	Real Number	The value of total temperature behind a normal shock. This is constant across a shock and is provided for completeness.
Normal Shock Downstream Static Pressure	Pressure	Real Number	The value of static pressure behind a normal shock - static pressure increases behind shocks.
Normal Shock Downstream Total Pressure	Pressure	Real Number	The value of total pressure behind a shock. There is a loss across the shock, reflected by a loss of total pressure across the shock.
Normal Shock Downstream Density	Density	Real Number	The value of density behind a normal shock - density increases behind shocks.
Normal Shock Downstream Dynamic Viscosity	DynamicViscosity	Real Number	The value of dynamic viscosity behind a normal shock.
Normal Shock Downstream Kinematic Viscosity	KinematicViscosity	Real Number	The value of kinematic viscosity behind a normal shock.
Normal Shock Downstream Reynolds Number per meter	Unitless	Real Number	The value of Re per meter behind a normal shock.
Normal Shock Downstream Reynolds Number - Log10	Unitless	Real Number	The value of Log10(Re per meter) behind a normal shock.