/Planning & Performance
/General Planning # Aviation Calculations, Formulas

Preflight planning is a very important element of any flight and especially so when going on a cross country flight. There are a number of items to be done in preparation for a VFR cross country in such a way that nothing is overlooked and the intended flight is done as safely as possible.

The pilot will (must) perform a number of calculations during preflight planning and those we use on the site are listed below for convenient access. Sometimes the use of a special aviation calculator (E6B models or electronic Jeppesen) is required, other times it can be done without the use of such devices. Have a look at our E6B Tools too, click here for that!

## Aviation Formulas

As a reference, we compiled a list of formulas we used throughout the site on the panels below:

### Flight planning

Compass Heading: TC +/-WCA = TH +/-VAR = MH +/-DEV = CH

Estimated Time Enroute (ETE): Time = Distance / Speed

Weight Shift problems: Distance Weight Shifted × Weight Shifted = Total Weight × Delta C of G

Track Error (1 in 60 rule): TE = (60 / Distance Flown ) × Distance to Track

Closing Angle (1 in 60 rule): CA = (60 / Distance To Go) × Distance to Track

### Aerodynamics

Load Factor: G = 1 / cos (Bank Angle) or G = L / W

Higher Stall Speed in a turn: Vsacc = Vs × √ Load Factor

Increased Stall Speed at higher weight: Vs new = Vs Old Weight × √(New Weight / Old Weight)

Lift Formula: L = ½ ρ V2 × S × CL or simplified: Lift = IAS × CL

Dynamic Pressure (IAS): IAS = ½ ρ V2

True Airspeed (TAS): TAS = IAS × √ (ρ0 / ρ)

Propeller Efficiency: Thrust × TAS / Brake Horse Power

Propeller Tip Speed (π is PI, 3.1415...): VTIP = π d N

### Aircraft performance

Pressure Lapse Rate: PLR = 96 × T (Kelvin) / QNH (hPa)

Pressure Altitude: Pressure Altitude = Altitude + (1013 - QNH) × 27

Density Altitude: Density Altitude = Pressure Altitude + (OAT - ISATpa) × 120

Specific Air Range (SAR): SAR = (TAS / Power) × (1 / SFC)

Specific Ground Range (SGR): GS / Fuel Flow or GS / Power

Best Specific Fuel Consumption (SFC): SFC = TAS / Power

### Physics

Kinetic Energy (Joule): Ek = ½ × m × V2

Potential Energy (Joule): Ep = m × g × h

Elastic Energy (Joule): Ee = ½ × k × x2

Force (Newton): F = m × a

Work (Nm or Joule): W = Force × Distance

Power or the Rate of doing Work (Watt or J/s): Power = Work / Time

Speed of Sound: Vsound = 331,3 √ (1 + T / 273,15)

Ideal Gas Law: p × V = n × R × T

### Engines

Engine Power (π is pi, 3.141529...): BHP = ((2 π × RPM) / 60) × Torque

Engine Efficiency: Brake Thermal Efficiency = Brake Power / Fuel Consumption

Engine SFC: Brake Specific Fuel Consumption = Fuel Flow / Brake Power

### Electronics

Light Power, Luminous Flux: 1 lm = cd.sr in Lumens (lm)

Ohms Law: U = I × R in V

Electrical Power: P = U × I in W

Electrical Energy: E = P × t in Wh

VHF Communications Range: Range = 1,33 (√H-aircraft + √H-gs) in NM

###### written by EAI.

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