The Use of Pressure Fluctuations on the Nose of an Aircraft for Measuring Air Motion

Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

“…The probe is a hemispherecylinder configuration in which a hemispherical surface is at the end of a 2.5 cm diameter, 12.5 cm long cylindrical section. Pressure measurements on ports in a hemispherical surface are used for airspeed and flow angle determination (Brown et al, 1983). There are 5 ports: one central port which approximates total pressure, two ports separated by …”

“…The sensitivity coefficient, assuming potential flow (using a sensitivity factor, as defined in the Appendix, f = 9/4) for small angles, is K ∼ = 2f (π/180) = 0.0785 deg −1 . Brown et al (1983) investigated K using data from flight maneuvers for the R858 on the noseboom on the NCAR Sabreliner. They found that for N Mach < 0.5, K = 0.068 deg −1 (f = 1.95), 13 % lower than the value recommended in Rosemount (1976).…”

“…This determination of K was not exact nor without ambiguities, however. The Brown et al (1983) method substituted precise IMU-measured pitch angle for attack angle, which is valid during periods of straight and level flight assuming zero vertical wind and aircraft vertical velocity. Using pitch in this manner, the upwash effect (Crawford et al, 1996) of the fuselage, wings, and possibly the R858 itself is incorporated into the value of K. The sense of upwash effect is to make the local attack angle larger than the pitch angle, causing K to be overestimated compared to the local value of K without the upwash effect.…”

Characterization of turbulent transport in the marine boundary layer during flight 7 of PEM‐Tropics A

“…The system consists of (1) a radome instrumented with differential pressure and air temperature sensors, (2) a highresolution inertial navigation system (INS), and (3) a data acquisition system. The radome differential pressure system measures pressure fluctuations on the nose of the airplane to determine the angle of ambient airflow relative to the aircraft [Brown et al, 1983;Larson et al, 1980]. This technique required installing four flush pressure ports (each with a diameter of -0.6 cm) arrayed in a cruciform pattern at nominal 33 ø separation angles from the stagnation point of the P-3B radome.…”

“…A port installed at the radome air stagnation point and linked to existing static pressure ports on the side of the fuselage was used to provide the required dynamic and total pressure measurements. Rosemount model 858Y hemispherical flow-direction sensors JArmisread and Webb, 1973; Brown et al, 1983] were mounted on the top and port side of the fuselage just aft of the cockpit as a backup for the radome airflow angle measurements. All pressure transducers were maintained at cabin pressure and temperature and located as closely as possible to their respective pressure ports to minimize delays and errors associated with long pressure tubes.…”