The static system measures the static pressure. So all influences of airspeed are eliminated. In real life this is however not always easy. Effects from angle of attack, side-slip, flap defection, gear extension, engine power setting and airspeed are present and for the aircraft designer it is not always easy to find a good position for the static port.
Usually the number of static systems are equal to the number of pitot systems.
In Flightgear there are 3 types of static systems modeled.
- Type 0 (default): the perfect sensor. No measurement failures.
- Type 1: Dual static ports on the fuselage sides. Side-slip angle influence only.
- Type 2: Static port on the pitot tube. Both angle of attack and side-slip influence.
If you want to use type 1 or 2:
<static> <name>static</name> <number>0</number> <tau>0.1</tau> <type>1</type> <error-factor>0.5</error-factor> </static>
The output property /systems/static[n]/pressure-inhg is filtered. Therefore, if you want to see the effect of the measurement failure, "tau" should be 0.1 or smaller. The "error-factor" should be between 0.2 and 0.7. Setting it to 0 equals a "perfect sensor". A setting of 1 means the whole (projected on static port face) impact pressure is applied. This is not realistic as usually there are more than one static pick-up points and so the pressure increase gets "flattened".
The "tau" parameter controls the responsiveness of the filter that is applied after the calculation of the new values (responsiveness = dt/tau).