[Aerospace] Fundamentals of Flight: Part 3

Aerospace Engineering Units
Before we move on any further, it is probably important to talk about some customs of the aerospace world. In the aviation world, travel distance are measured in nautical miles and speed is measured in knots. 1 nautical mile (nm) = 1.15 miles and 1 knot = 1.15 mph.  This system is developed such at 1 degree of Earth’s longitudinal length is equals to 60 nautical miles. For space, we sometime use AU, Astronautical Unit, 149.6E9 m, distance between Earth and Sun. In engineering, we generally use Imperial system for aviation and Metric for space. But both works and I prefer metric. Remember the standard units when calculating: use seconds for time, meter or feet for distance, m/s or fps for speed (60 mph = 88 fps), kg or slugs for mass, Newtons or pounds for force, Kelvins (+273.15 C) or Rankine (+459.67 F) for absolute temperature.

Ideal Gas Law
Since our atmosphere is made out of 79% N2 and 20% O2, the ideal gas law from Chemistry is very important in our calculation for inner-atmospheric flight. Given certain parameters of the current flight condition, we are able to find the rest with this relationship:

P = ρRT

P = pressure (pound per square feet or N/m2)
ρ = density of air (slug/ft3 or kg/m3)
R = specific gas constant (1716 ft-lb/slug R or 287 N-m/kg K)
T = absolute temperature (R or K)

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2 thoughts on “[Aerospace] Fundamentals of Flight: Part 3

  1. Pingback: [Aerospace] Fundamentals of Flight: Part 2 | Billwaa's Blog

  2. Pingback: [Aerospace] Fundamentals of Flight: Part 2 | Billwaa's Blog

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