The DC-8 Meteorological Measurement System (MMS) consists of three major systems: an air-motion sensing system to measure air velocity with respect to the aircraft, an aircraft-motion sensing system to measure the aircraft velocity with respect to the earth, and a data acquisition system to sample, process, and record the measured quantities.
The air-motion system consists of two airflow-angle probes, three total temperature probes, with different response time, a pitot-static pressure probe, and a dedicated static pressure system. All probes and sensors are judiciously located at specific positions of the fuselage. The aircraft-motion sensing system consists of an embedded GPS ring laser inertial navigation system (Litton LN-100G), and a multiple-antenna GPS attitude reference system (Trimble TANS Vector). The data system rack is located near station 840, and customized software was developed to control, sample, and process all sensors and hardware.
Primary products (1 Hz and 5 Hz)
| Typical value at 40,000 ft | Accuracy | |
|---|---|---|
| Pressure | =~ 200 mb | +/- 0.3 mb or =~ 0.5% |
| Temperature | =~ 220 K | +/- 0.3 K or =~ 0.2% |
| Horizontal Wind | =~ 30 m s-1 | +/- 1 m s-1 or =~ 4.0% |
| Vertical Wind | < 1 ms-1 (Resolution: 0.1 m s-1) |
Secondary Products (1 Hz and 5 Hz)
| Calculated | potential temperature, true-air-speed, turbulence (0.8 - 1.5 Hz) |
|---|---|
| Measured | positions, velocities, accelerations, pitch, roll, heading, angle of attack, angle of sideslip dynamic and total pressures, total temperatures |