What is the TAS at MACH 0.74 and -40 degrees Celsius?

To calculate True Airspeed (TAS) at a specific Mach number and temperature, you can use the formula that relates TAS to Mach number (M) and the speed of sound. The speed of sound varies with temperature and can be calculated using the formula:

Speed of Sound (at temperature T in Celsius) = 39.94 * √(T + 273.15)

At -40 degrees Celsius, this calculation would yield:

1. Convert temperature to Kelvin: -40 + 273.15 = 233.15 K.

2. Calculate the speed of sound:

Speed of Sound = 39.94 * √(233.15) ≈ 39.94 * 15.27 ≈ 610.42 m/s.

To convert this speed to knots (1 m/s ≈ 1.94384 knots):

610.42 m/s * 1.94384 ≈ 1185.33 knots.

Now, to find TAS when flying at Mach 0.74:

TAS = Mach number * Speed of Sound

TAS = 0.74 * 1185.33 ≈ 878.36 knots.

Converting knots to miles per hour (1 knot ≈