Integrated Noise Model Accuracy for General Aviation Aircraft (2014) / Chapter Skim
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From page 35... ...
7 Detailed Analysis–Causes of Error: Test Examples As suggested by the Panel, we focused our analysis more on specific details of the aircraft flight profiles in the INM than on the internal workings of the INM. However, we did a review of INM equations and coefficients used for modeling the aircraft.
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From page 36... ...
reasonable thrust at that point that produces the best approximation to the desired SEL. The resultant "best fit" discrepancies of SEL and altitude are given.
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Figure 7 LJ35 measured and modeled departure SEL Figure 8 LJ35 measured minus modeled departure SEL 36
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Figure 9 LJ35 measured and modeled departure altitude profiles Figure 10 compares the standard INM LJ35 departure profile, all the radar returns, the best fit profile and a polynomial fit. The red lines identify the 12,000 foot track distance used for all departure discrepancy calculations and the average radar altitude at that track distance.
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From page 39... ...
Figure 10 LJ35 departure altitudes: all radar data, INM, best fit, and polynomial fit 7.1.2 GLF4 The GLF4 was chosen for detailed analysis because its discrepancy is positive – the INM modeled SEL is lower than the measured SEL, while its altitude is higher than the measured altitudes. Hence, correcting the altitude may reduce the discrepancy.
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Table 12 GLF4 measured and modeled departure results summarized Designator INM Aircraft Type Measured SEL (dB) Modeled SEL (dB)
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Figure 12 GLF4 measured minus modeled departure SEL Figure 13 GLF4 measured and modeled departure altitude profiles 40
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Figure 14 compares the standard INM GLF4 departure profile, all the radar returns, the best fit profile and a polynomial fit.28 The measured minus modeled SEL value with the best fit profile is now -0.2 rather than +3.9. The modeled altitude is 16 feet lower than the measured altitude.
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From page 43... ...
Table 13 EA50 sample size of database by airport Number of Tracks w/ SEL Airport A D BED 3 28 BWI 0 0 DEN 1 0 FXE 4 0 HPN 80 11 VNY 116 160 TOTAL 204 199 Table 14 EA50 measured and modeled departure results summarized Designator INM Aircraft Type Measured SEL (dB) Modeled SEL (dB)
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Figure 16 EA50 measured minus modeled departure SEL Figure 17 EA50 measured and modeled departure altitude profiles 43
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Figure 18 provides the comparison of the standard INM EA50 departure profile with all the radar returns, the best fit profile and a polynomial fit.29 The measured minus modeled SEL value with the best fit profile is now +0.4 rather than +3.7. The modeled altitude is 7 feet higher than the measured altitude.
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From page 46... ...
7.2.1 C56X Table 15 C56X sample size of database by airport Number of Tracks w/ SEL Airport A D BED 69 290 BWI 49 69 DEN 14 0 FXE 87 39 HPN 2388 64 VNY 853 910 TOTAL 3460 1372 Table 16 C56X measured and modeled arrival results summarized Designator INM Aircraft Measured SEL (dB) Modeled SEL (dB)
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Figure 20 D56X measured minus modeled arrival SEL Figure 21 C56X measured and modeled arrival altitude profiles 46
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From page 48... ...
7.2.2 GLF5 Table 17 GLF5 sample size of database by airport Number of Tracks w/ SEL Airport A D BED 23 85 BWI 25 9 DEN 3 0 FXE 35 29 HPN 1054 86 VNY 1107 1138 TOTAL 2247 1347 Table 18 GLF5 measured and modeled arrival results summarized Designator INM Aircraft Measured SEL (dB) Modeled SEL (dB)
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Figure 23 GLF5 measured minus modeled arrival SEL Figure 24 GLF5 measured and modeled arrival altitude profiles 48
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7.2.3 F900 Table 19 F900 sample size of database by airport Number of Tracks w/ SEL Airport A D BED 0 0 BWI 24 10 DEN 0 0 FXE 0 0 HPN 0 0 VNY 325 340 TOTAL 349 350 Table 20 F900 measured and modeled arrival results summarized Designator INM Aircraft Measured SEL (dB) Modeled SEL (dB)
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Figure 26 F900 measured minus modeled arrival SEL Figure 27 F900 measured and modeled arrival altitude profiles 50
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