Originally Posted by
skwinty
What happens then with supersonic aircraft?
I don't have all the figures at hand, sorry.
But one well-known phenomenon on Concorde occurs when 'breaking the sound barrier', or better expressed, when accelerating past Mach 1.
A shock wave then moves from the nose along the fuselage past the static ports.
It's barely visible on the altimeter, but there is a
very noticeable 'twitch' on the VSI (there are videos of that, and we've even managed to simulate it on the Brooklands Concorde simulator).
Do they suffer from serious altitude increases due to velocity induced pressure errors?
As said, the "drilling of the little hole" is very much trial-and-error to find the location which produces the least errors. The final location may introduce altitude
increases or
decreases as a function of airspeed, depending on the exact effects of the airflow and pressure 'distribution' at that exact location.
After all, aircraft have been going supersonic for years without computers.
Sure, but in that era nobody cared about a few hundred feet error in indicated altitude......
Also, most of those aircraft carried a calibrated pitot-static 'boom'. Airliners don't.
CJ