Calculate relative atmospheric ratios
Aerospace Blockset / Flight Parameters
The Relative Ratio block computes the relative atmospheric ratios, including the relative temperature ratio (θ), , relative pressure ratio (δ), and relative density ratio (σ).
θ represents the ratio of the air stream temperature at a chosen reference station relative to sea level standard atmospheric conditions:
δ represents the ratio of the air stream pressure at a chosen reference station relative to sea level standard atmospheric conditions:
σ represents the ratio of the air stream density at a chosen reference station relative to sea level standard atmospheric conditions:
The Relative Ratio block icon displays the input units selected from the Units parameter.
For cases in which total temperature, total pressure, or total density ratio is desired (Mach number is nonzero), the total temperature, total pressure, and total densities are calculated assuming perfect gas (with constant molecular weight, constant pressure specific heat, and constant specific heat ratio) and dry air.
[1] Aeronautical Vestpocket Handbook, United Technologies Pratt & Whitney, August, 1986.