Details
Static Pressure
The Rosemount Model 1501 is a digital solid state sensor providing low frequency high precision static pressure measurements. The principal of operation is a mechanical vibrating element controlled by an integral electronic oscillator to output a frequency proportional to the applied pressure. Digitized data are output and recorded via ARINC 429 bus.
The Rosemount Model 1201F2 is an analog capacitive sensor providing high frequency (100 Hz) static pressure measurements. The principal of operation is the capacitive measurement of the deflection of a diaphragm against a reference vacuum.The static pressure port is part of the deiced Rosemount five hole probe located at the tip of the nose boom.The measured static pressure has to be corrected for the static pressure error caused by the airflow disturbance of the aircraft . This error was determined by extensive in-flight calibration using a trailing cone reference measurement system.
All pressure sensors are housed in a temperature stabilized box to minimize temperature drift errors of the sensors and electronics.
Dynamic Pressure
The Rosemount Model 1221F2 is an analog capacitive sensor providing high frequency (100 Hz) differential pressure measurements. The principal of operation is the capacitive measurement of the bi-directional deflection of a diaphragm against a reference pressure port.The dynamic pressure port is part of the deiced Rosemount five hole probe located at the tip of the nose boom. As reference pressure port the static pressure port of the five hole probe is used.
Error Analysis
The calibration is accurate to 0.1 hPa. The error in the calculated static pressure is dominated by the static source error which was determined via extensive flight experiments using the trailing cone technique. The final error in the static pressure measurement is about 0.5 hPa.Pressure sensors are calibrated by the DLR flight department using sophisticated calibration equipment developed within the division. Each calibration procedure is tracable to the national standard and includes an extensive error analysis.