Decision height was assumed to be 200ft which also

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decision point. Decision height was assumed to be 200ft, which also supported the use of desirable deceleration schedules of 0.7 to 1 kt/s as mentioned above. The resulting RASCAL specific noise-abatement approach profile is shown in figure 2(c). Flight Test Matrix A total of 8 test points ranging from the test point A to test point H, as shown in table 1, were flown in the acoustic tests. The first two test points, A and B (level flight at 80 knots, and 6 deg descending flight at constant airspeed of 80 kt respectively) were flown for the purpose of obtaining data which could be compared with data measured for another helicopter similar to the RASCAL. These two test points were flown such that the helicopter passed at an altitude of 250 ft over the center microphone (ref. 6). The remaining 6 test points (C through H) were flown at a higher altitude of 400 ft ; this is conducted in according with the ICAO and FAA noise certification practices (ref. 8), and for the purpose of providing a flight database consistent with previous FAA/industry tests with a number of helicopters (refs.9–11). In addition to the three noise-abatement approach profiles (i.e., test points F, G, and H) discussed above, three stan- dard descending approaches (9 deg decelerating, 6deg decelerating, and 6 deg constant speed at 80knots cor- responding respectively to test points D, E, and C) were also flown. These additional test points were designed to permit an assessment of the effects of decelerating approach flight and flying single- and multi-segment approach profiles on the noise characteristics and the associated tracking performance. The deceleraton level of the two single-segment approach profiles, D and E, was also set at the value of around 0.7 to 1 kt/s. Test points C, D, and E were flown in a traditional manner by intercept- ing the desired flightpath from below the extended glide- slope and at specified initial speeds (100 kt for 6 deg, and 65 kt for 9 deg). The set up of the flight experiment is dis- cussed next. Flight Experiment Setup The acoustic tests were conducted at Crows Landing Air- field, Calif. in January 1995. Figure 7 shows the plan view of the facility and the general arrangement of the flight experiment. The helicopter final approach flight track is along the centerline of Runway 35 passing over the two center microphones (the ground board micro- phone #2 and the tripod stand microphone #3) of the array of 4microphones. The helipad was located near the “STOL aim point,” which was made “movable” to achieve the scheduled flyover altitude of 400 ft above the center microphone #2 for each of the 6 main approaches (test points C to H). For the other two test points, A and B, the scheduled flyover altitude was 250 ft above the center microphone #2. A precision laser tracker, near the “NASA complex,” which houses the control room of the experiment, was used to assess the navigational accuracy of the LDGPS. The ground station of the LDGPS was located on the roof of a NASA complex building. Also shown in the figure is the location of the weather balloon
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