# Airframe Forces Calc

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The Airframe Forces Calculator computes basic forces, weights and speeds associated with forces exerted on an aircraft.    Forces on motion in flight.

### Functions

The functions in this calculator are as follows:

1. Force of Lift - this computes the force of lift on an aircraft based on lift coefficient, density of air, surface area and velocity.
2. Force of Drag - this computes the force of lift on an aircraft based on lift coefficient, density of air, surface area and velocity.
3. Speed - Lift - Weight - this computes the required airspeed needed to overcome the weight of the aircraft to produce positive lift.
4. Correction Angle - this is the azimuth correction angle for flight based on wind speed and direction
5. Ground Speed - this computes the ground speed for a flight based on on wind speed and direction

## Force of Drag (the math)

The default units are Pa - kg/m3, Cd - N/A, A - m2, V - m/s.

### Measured Drag Coefficients (Cd)

The graphic shows some common drag coefficients based on the shape of the object.  Note, that there are other factors besides shape that can effect drag.

Graphics courtesy of Wikipedia (Drag coefficient)

### Density of Air

The density of air, ρ (Greek: rho) (air density), is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in temperature or humidity. At sea level and at 15 °C, air has a density of approximately 1.225 kg/m3 (0.001225 g/cm3, 0.0023769 slug/ft3, 0.0765 lbm/ft3) according to ISA (International Standard Atmosphere).

• At IUPAC standard temperature and pressure (0 °C and 100 kPa), dry air has a density of 1.2754 kg/m3 (the default above).
• At 20 °C and 101.325 kPa, dry air has a density of 1.2041 kg/m3.
• At 70 °F and 14.696 psi, dry air has a density of 0.074887lbm/ft3.

## Force of Lift (the math)

The lift formula uses many of the same parameters as drag, except the lift coefficient (rho) differs from the drag coefficient.

Lift = 1/2*A*rho*CL*V^2