Plausibility Check for Pressure Differences
![]() |
Picture: A321 MFS X |
Can the movement/acceleration of air and thus the creation of pressure ranges be sufficient to keep an aeroplane in the air or must there not be unknown forces at play that need to be uncovered?
We assume a pressure difference of ~ 1/300 bar between the top and bottom of the wing and an air pressure of 1000 mbar (hPa). With the frequently assumed pressure spreading of 1/3 positive pressure from below and 2/3 negative pressure above, the ratio would be 1001.1 mbar below (~1.1 mbar positive pressure) and 997.8 mbar above (~2.2 mbar negative pressure). 10200 kp/m² / 300 *12m² = 408 kp - yes, that could be enough - very ambitious - perhaps an microlight glider.
An A320 does not require 3.3 mbar (hPa), but a pressure difference of around 60 hPa, depending on the configuration. Not even that impressive as the weather-related air pressure fluctuations already measured can be up to 90 hPa. Low-pressure weather above the wing, high-pressure weather below the wing.
The pressure gradient within the pressure ranges (and thus the pressure conditions that act directly on the wing surface) is neglected here for the sake of simplicity, so these calculations are gross simplifications, but are permissible as a plausibility check.
Bernoulli and The Energy Conservation Principle ⇐ | ⇒ Flow and The Windtunnel