dynamics.models.uav

Class AerodynamicsFunctions

java.lang.Object

dynamics.models.uav.AerodynamicsFunctions

public class AerodynamicsFunctions
extends Object

Implements utility functions and constants relative to aerodynamics. All calculations are based on a "standard day": 29.92" Hg, 288.15 deg K (15C) at sea level and adiabatic cooling of 2 deg K per 302.6m (1000 ft) altitude.

Version:

$Id: AerodynamicsFunctions.java 8020 2012-07-03 01:37:06Z brutzman $

History:

     Date:     14 August 2004
     Time:     
     Author:   Duane Davis
     Comments: Initial

     Date:     October 25, 2006
     Time:     1156
     Author:   Douglas Wahl
     Comments: Per Don B. refactored to AerodynamicsFunctions for better 
               naming convention.  Declared P_ZERO and T_ZERO as final 
               constants.
   

Author:

Duane Davis

See Also:

dynamics.models.uav

Field Summary

Fields

Modifier and Type	Field and Description
static double	ADIABATIC_COOLING_RATE standard adiabatic cooling rate (degrees per meter)
static double	G accelleration due to gravity (meters per second squared)
static double	KAPPA adiabatic index for air
static double	M average molecular mass of the atmosphere (kg per mole)
static double	P_ZERO standard air pressure (Pascals) at mean sea level
static double	R universal gas constant
static double	T_ZERO temperature (degrees Kelvin) at mean sea level

Constructor Summary

Constructors

Constructor and Description
AerodynamicsFunctions()

Method Summary

Methods

Modifier and Type	Method and Description
static double	densityAtAltitude(double altitude) Computes the air density (rho) at a specified altitude (assumes dry air)
static double	dynamicPressure(double altitude, double v) Computes the dynamic pressure of the airfoil given a velocity vector
static double	machNumber(double altitude, double velocity) Computes the mach number at a specified altitude for a specified velocity
static double	pressureAtAltitude(double altitude) Computes the air pressure at a specified altitude Formula assumes dry air and utilizes equations available at http://www.atmosphere.mpg.de/enid/16h.html
static double	speedOfSound(double altitude) Computes the speed of sound at a specified altitude
static double	temperatureAtAltitude(double altitude) Computes the temperature (degrees K) at a specified altitude based on a standard day (29.92" Hg and 15 degrees C at sea level) and standard adiabatic adiabatic cooling rate of 2 degrees C (K) per 1000' (302.6m)
static double	viscosityAtAltitude(double altitude) Generates a dynamic viscosity (mu) for a specified altitude This function is based on tabular data available online at http://www.engineeringtoolbox.com/24_601.html.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

P_ZERO

public static final double P_ZERO

standard air pressure (Pascals) at mean sea level

See Also:

Constant Field Values

T_ZERO

public static final double T_ZERO

temperature (degrees Kelvin) at mean sea level

See Also:

Constant Field Values

ADIABATIC_COOLING_RATE

public static final double ADIABATIC_COOLING_RATE

standard adiabatic cooling rate (degrees per meter)

See Also:

Constant Field Values

R

public static final double R

universal gas constant

See Also:

Constant Field Values

KAPPA

public static final double KAPPA

adiabatic index for air

See Also:

Constant Field Values

M

public static final double M

average molecular mass of the atmosphere (kg per mole)

See Also:

Constant Field Values

G

public static final double G

accelleration due to gravity (meters per second squared)

See Also:

Constant Field Values

Constructor Detail

AerodynamicsFunctions

public AerodynamicsFunctions()

Method Detail

temperatureAtAltitude

public static double temperatureAtAltitude(double altitude)

Computes the temperature (degrees K) at a specified altitude based on a standard day (29.92" Hg and 15 degrees C at sea level) and standard adiabatic adiabatic cooling rate of 2 degrees C (K) per 1000' (302.6m)

Parameters:

altitude - meters above mean sea level

Returns:

degrees Kelvin

speedOfSound

public static double speedOfSound(double altitude)

Computes the speed of sound at a specified altitude

Parameters:

altitude - meters above sea level

Returns:

meters per second

machNumber

public static double machNumber(double altitude,
                double velocity)

Computes the mach number at a specified altitude for a specified velocity

Parameters:

altitude - meters above sea level

velocity - meters per second

Returns:

dimensionless mach number

pressureAtAltitude

public static double pressureAtAltitude(double altitude)

Computes the air pressure at a specified altitude Formula assumes dry air and utilizes equations available at http://www.atmosphere.mpg.de/enid/16h.html

Parameters:

altitude - meters above mean sea level

Returns:

pressure in Pascals (mb * 100)

densityAtAltitude

public static double densityAtAltitude(double altitude)

Computes the air density (rho) at a specified altitude (assumes dry air)

Parameters:

altitude - meters above mean sea level

Returns:

air density in kilograms per meter cubed

dynamicPressure

public static double dynamicPressure(double altitude,
                     double v)

Computes the dynamic pressure of the airfoil given a velocity vector

Parameters:

altitude - meters mean sea level

v - scalar velocity in meters per second

viscosityAtAltitude

public static double viscosityAtAltitude(double altitude)

Generates a dynamic viscosity (mu) for a specified altitude This function is based on tabular data available online at http://www.engineeringtoolbox.com/24_601.html. Intermediate values are linearly interpolated (technically speaking, not completely accurate, but should be reasonable within a couple of decimal places

Parameters:

altitude - meters above sea level