TigerShark UAS Level Flyover Noise Measurements

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1 TigerShark UAS Level Flyover Noise Measurements Final 18 July 216 Adrian Sescu, Calvin Walker, Ratan Jha Mississippi State University Prepared for: Federal Aviation Administration Office of Environment & Energy PoC: Mehmet Marsan, Ph.D. 1 P age

2 1. Introduction FAA s Office of Environment and Energy (AEE) is supporting the FAA Unmanned Aircraft Systems (UAS) Integration Office to ensure the safe, efficient, and timely integration of UAS into the United States National Airspace System (NAS). In order to fulfill this mission, the FAA is developing UAS standards, procedures, and regulatory products. The primary control over aircraft source noise is the noise certification process, which is the responsibility of AEE within the FAA. This document describes the TigerShark UAS level flyover noise measurements that were performed at Griffiss International Airport, Rome NY, on May Test Aircraft Airplane information to be reported under Section G36.9(g) Tiger Shark is a medium weight UAS. It is powered by a Herbrandsen 372 engine with 31 x 18 blade propeller. Maximum Takeoff Weight is 397 lbs. Table 1: UAS specifications Type NASC TigerShark Model Block 3 Serial numbers (if any) 52 N173X Modifications that would affect the noise characteristics None 32 hp / 8, rpm Engine performance 2 blades 6, rpm with 31 X 18 prop. Maximum takeoff weight (lbs.) Measurement Site Acoustical considerations in selecting the measurement site location included the following: To minimize the effect of altitude on aircraft performance, the elevation of the measurement site should be below 2, feet above mean sea level (AMSL); To lessen the risk of external acoustic contamination, a measurement site should have a relatively quiet ambient environment with very few daily aircraft operations; and To eliminate the need of acoustic corrections due to terrain undulations, the measurement site should have a long stretch of flat terrain near the test runway, where a centerline and sideline microphone can be placed Test Site Name: NY Griffiss UAS Test Site Airport Name: Griffiss International Airport, Rome NY (KRME) 2 P age

Table 2: Points of Contact Contact Phone Email Raymond Young (2) 525-15

3 Table 2: Points of Contact Contact Phone Raymond Young (2) Instrumentation 4.1. Acoustic System The MSU acoustic system (Bruel & Kjaer) consists of: o Two 22-G4 Hand-held Analyzers (figure 1) with Level Meter, Frequency Analysis, Enhanced Logging and Recording Software (Qty: 2). Characteristics of the Type 4189 microphone: Sensitivity: mv/pa Frequency: 6.3Hz. 2 khz Dynamic Range: db Temperature:.3 to +1 C (.22 to +32 F) Polarization: Prepolarized o One Calibrator Class 1 and LS, 94 and 114 db, 1 khz o Two 1/2" Pressure-field Microphones, 3 Hz to 2 khz, 2V Polarization (Qty: 2). Characteristics of the Type 4192 microphone: Sensitivity: 12.5mV/Pa Frequency: 3.15 Hz. 2 khz Dynamic Range: db Temperature:.3 to +3 C (.22 to +572 F) Polarization: 2V o One laptop to acquire and post-process the data; o 2 tripods Meteorological System Figure G4 B&K Analyzer Wind speed and direction, relative humidity, air temperature, and barometric pressure at specified time intervals (typically, in the orders of seconds) were collected by the Volpe 3 P age

4 team. However, the meteorological data were collected by Volpe only during the takeoff noise measurements. For the level flyover measurements, approximate values for wind speed, average temperature and humidity were collected from the internet, which are included in section Global Positioning System The time-space position information of the test aircraft during the takeoff and flyover noise certification tests was provided by NASC. The global positioning system (GPS) was used as the primary aircraft guidance and tracking system during measurements. 5. Measurements Procedures The tests were performed as follows: Three level flyovers in each direction for two separate flight altitudes (i.e., 12 total runs). Flight altitudes are: 2 feet and feet (NASC tram could not perform flights at and ft as originally planned because of some flight safety issues: tall trees were present in the area). During the measurements, the wind speed was below 2 m/s, the averaged temperature varied between 45 and F, and the humidity varied between 68% and %. Calibration of the microphones The microphones were calibrated using the following procedure: Mount the B&K 4231 calibrator on the microphone. Activate the calibrator with a sine wave signal of 94 decibels (db) at 1 khz. Calibrate the microphones to this reference signal. After calibration, record one minute of the calibration signal and note levels indicated on the log sheets. Apply a microphone simulator to the preamp to measure the system noise floor and ensure no outside interference is present. Apply a +2 db gain to raise the sensitivity of the meter to help identify any anomalous signals. Record one minute of the noise floor and note levels indicated on the log sheets. Reinsert the microphone and reapply the calibrator to verify that the analyzer reads the same initial calibration reading performed in Step 1. Record another minute of the calibration signal and note levels indicated on the log sheets. Number of measurements: 3 level flyovers in each direction for each flight altitude, i.e. 12 total runs: Flight altitudes are: 2 ft and ft 4 P age

5 Figures 2 and 3 show a front and a top view of the measurement setup, while figure 4 shows an example of a flight path. One microphone was positioned under the flight path, while the other one was positioned at feet from the first in the lateral direction. Both of them were places at 4 feet from the ground. 2 ft, ft Figure 2. View from the front Level flyover Microphone on tripod Figure 3. View from the top Level flyover 5 P age

Figure 4. Test site (red dot represents the location of the microphones) 6. Data Analysis Field elevation: 3.7 ft level meter #1 location: 43 13.223 N 75 23.283 W level meter #2 location: 43 13.

6 Figure 4. Test site (red dot represents the location of the microphones) 6. Data Analysis Field elevation: 3.7 ft level meter #1 location: N W level meter #2 location: N W The NASC team was not able to fly the UAS at and feet because of flight safety issues (trees were present in close proximity to the measurement site). Next table lists the heights, headings, rotational speed of the engine and the maximum noise attained at the two microphones. More data about the collected noise are included in the appendix B. Table 3 Event Test height Heading RPM Microphone #1 Microphone #2 (feet) LASmax LCpeak LASmax LCpeak P age

7 Figures 5-12 show time histories of LAFmax, LAFmin, LCpeak and LAeq, while figures show spectra history of (for several instances in time) for all cases. The gray vertical bands in the time history plots (figures 5-12) represent the instant in time corresponding to the maximum values, when the UAS was in the closest proximity to the sound level meater. The definitions of LAFmax, LAFmin, LCpeak, LAeq, and are given in the appendix. -The maximum LAeq for the level flight at 2 m perceived by microphone # 1 was 92.8 db, while for the microphone # 2 it was 84.6 db (the corresponding LCpeak levels were 1.6 db and 98.7 db, respectively). -The maximum LAeq for the level flight at m perceived by microphone # 1 was 87.5 db, while for the microphone # 2 it was 84.6 db (the corresponding LCpeak levels were 7.6 db and 3.3 db, respectively). Spectra plots for in figures show that the peak is approximately Hz. All spectra plots show a spike around Hz, which corresponds to the first harmonic tone of the propeller (some of the plots also show a couple of multiple tones). 7 P age

8 Soun d Cur sor val ues Rep or t [ db] X: 8 :28 :38 AM - 8: 2 9:13 AM LAe q: 6 9. db Log ged X: 8 :28 :57 AM - 8: 2 8:58 AM LAF max : 76.8 d B LAF mi n :75. 8 db LCp eak: db LAe q: db 8: 2 8: AM 8: 2 8:45 AM 8:2 8:5 AM 8:2 8:5 5AM 8: 29: AM 8 :29: 5A M8:29: A M 5/1 7/2 16 X: 9:27:47 AM - 9:28:23 AM LAeq: 68.3 db X: 9:28:8 AM - 9:28:9 AM LAFmax: 75.5 db LAFmin: 74.1 db LCpeak: 92.5 db LAeq: 74.9 db 9:27:48 AM 9:27:54 AM 9:28: AM 9:28:6 AM 9:28:12 AM 9:28:18 AM 1 X: 9:31: AM - 9:32:2 AM LAeq: 79.8 db X: 9:32:2 AM - 9:32:3 AM LAFmax: 91. db LAFmin: 88.6 db LCpeak: 5.4 db LAeq: 89.8 db 9:31: AM 9:31:55 AM 9:32: AM 9:32:5 AM 9:32: AM 9:32:15 AM 9:32:2 AM 1 X: 9:39:5 AM - 9:39:34 AM LAeq: 81.5 db X: 9:39:18 AM - 9:39:19 AM LAFmax: 93.6 db LAFmin:.6 db LCpeak: 7.8 db LAeq: 92.6 db 9:39: AM 9:39:2 AM 9:39:3 AM Figure 5. Time histories of LAFmax, LAFmin, LCpeak and LAeq for the level flight at 2 feet (1 direction); microphone #1; events 1, 2 and 3 in table 3. 8 P age

9 Sou nd Cur sor valu es Rep or t X: 8 :28 :38 AM - 8: 2 9:13 AM LAe q: 6 9. db Log ged X: 8 :28 :57 AM - 8: 2 8:58 AM LAF max : 76.8 db LAF mi n: db LCp eak: db LAe q: db 8: 28:4 AM 8: 28:4 5 AM 8: 28:5 AM 8 :28: 5A M8:29: A M 8 : 29:5 AM8:29: AM 5 /17/ X: :12:33 AM - :13:5 AM LAeq: 81.6 db X: :12: AM - :12:51 AM LAFmax: 95.3 db LAFmin:.1 db LCpeak: 1.6 db LAeq: 92.8 db :12:36 AM :12:42 AM :12:48 AM :12:54 AM :13: AM 1 X: :15:46 AM - :16:5 AM LAeq: 82.7 db X: :15:51 AM - :15:52 AM LAFmax: 94. db LAFmin: 87.9 db LCpeak: 7.8 db LAeq: 91. db :15: AM :15:55 AM :16: AM :16:5 AM 1 X: :18:36 AM - :19: AM LAeq:.8 db X: :18:53 AM - :18:54 AM LAFmax: 94.2 db LAFmin: 88.1 db LCpeak: 8.3 db LAeq: 91.1 db :18:36 AM :18:42 AM :18:48 AM :18:54 AM :19: AM :19:6 AM Figure 6. Time histories of LAFmax, LAFmin, LCpeak and LAeq for the level flight at 2 feet (33 direction); microphone #1; events 4, 5 and 6 in table 3. 9 P age

10 Sou nd Cur sor valu es Rep or t X: 8 :28 :38 AM - 8: 2 9:13 AM LAe q: 6 9. db Log ged X: 8 :28 :57 AM - 8: 2 8:58 AM LAF max : 76.8 db LAF mi n: db LCp eak: db LAe q: db 8: 28:4 AM 8: 28:4 5 AM 8: 28:5 AM 8 :28: 5A M8:29: A M 8 : 29:5 AM8:29: AM 5 /17/ X: :32:42 AM - :33:22 AM LAeq: 76.3 db X: :33:4 AM - :33:5 AM LAFmax: 87. db LAFmin: 83.7 db LCpeak:.9 db LAeq: 85.2 db :32: AM :33: AM :33: AM :33:2 AM 1 X: :35:58 AM - :36:35 AM LAeq: 76.2 db X: :36:17 AM - :36:18 AM LAFmax: 86.8 db LAFmin: 82.4 db LCpeak:.7 db LAeq: 86. db :36: AM :36:6 AM :36:12 AM :36:18 AM :36:24 AM :36:3 AM 1 X: :39:22 AM - :39:52 AM LAeq: 77.9 db X: :39:39 AM - :39: AM LAFmax: 88.4 db LAFmin: 83.3 db LCpeak: 3.3 db LAeq: 86.6 db :39:24 AM :39:3 AM :39:36 AM :39:42 AM :39:48 AM :39:54 AM Figure 7. Time histories of LAFmax, LAFmin, LCpeak and LAeq for the level flight at feet (33 direction); microphone #2; events 1, 2 and 3 in table 3. P age

11 Sou nd 8: 28:4 AM 8: 28:4 5 AM 8: 28:5 AM 8 :28: 5A M8:29: A M 8 : 29:5 AM8:29: AM 5 /17/ 216 Cur sor valu es Rep or t X: 8 :28 :38 AM - 8: 2 9:13 AM LAe q: 6 9. db Log ged X: 8 :28 :57 AM - 8: 2 8:58 AM LAF max : 76.8 db LAF mi n: db LCp eak: db LAe q: db 1 X: :44:7 AM - :44:37 AM LAeq: 77.7 db X: :44:15 AM - :44:16 AM LAFmax: 88.9 db LAFmin: 83.7 db LCpeak: 3.3 db LAeq: 87.5 db :44: AM :44:15 AM :44:2 AM :44:25 AM :44:3 AM :44:35 AM 1 X: :47:8 AM - :47:37 AM LAeq: 77.2 db X: :47:17 AM - :47:18 AM LAFmax: 86.8 db LAFmin: 85.9 db LCpeak:. db LAeq: 86.4 db :47: AM :47:2 AM :47:3 AM X: ::15 AM - ::44 AM LAeq: 76.1 db X: ::24 AM - ::25 AM LAFmax: 84.6 db LAFmin: 81.7 db LCpeak: 98.8 db LAeq: 83.8 db ::2 AM ::3 AM :: AM Figure 8. Time histories of LAFmax, LAFmin, LCpeak and LAeq for the level flight at 2 feet (1 direction); microphone #2; events 4, 5 and 6 in table P age

12 [db ] 8: 28:4 A M8: 28:4 5 A M 8 :28: A M8:28:55 A M 8:29 : AM 8: 2 9:5 AM 8:2 9:1 AM 5 /17/ 216 Repor t X:8:2 8:3 8 AM - 8 :29: 13 AM L Aeq: 69. db Loged X:8:2 8:5 7 AM - 8 :28: 58 AM L AFm ax: 76.8 db L AFm in: 7 5.8dB L Cpea k: db L Aeq: db X: 8:28:38 AM - 8:29:13 AM LAeq: 69. db X: 8:28:57 AM - 8:28:58 AM LAFmax: 76.8 db LAFmin: 75.8 db LCpeak: 94.2 db LAeq: 76.2 db 8:28: AM 8:28:45 AM 8:28: AM 8:28:55 AM 8:29: AM 8:29:5 AM 8:29: AM 1 X: 8:32:37 AM - 8:33:5 AM LAeq: 79.9 db X: 8:32: AM - 8:32:51 AM LAFmax: 89.2 db LAFmin: 83.7 db LCpeak: 3.9 db LAeq: 88.1 db 8:32: AM 8:32: AM 8:33: AM 1 X: 8:39: AM - 8::2 AM LAeq: 82.6 db X: 8::6 AM - 8::7 AM LAFmax: 94.2 db LAFmin: 86.8 db LCpeak: 7.6 db LAeq: 92.6 db 8:39: AM 8:39:55 AM 8:: AM 8::5 AM 8:: AM 8::15 AM 8::2 AM Figure 9. Time histories of LAFmax, LAFmin, LCpeak and LAeq for the level flight at feet (1 direction); microphone #1; events 7, 8 and 9 in table P age

13 Soun d Cur sor val ues Rep or t [ db] X: 8 :28 :38 AM - 8: 2 9:13 AM LAe q: 6 9. db Log ged X: 8 :28 :57 AM - 8: 2 8:58 AM LAF max : 76.8 d B LAF mi n :75. 8 db LCp eak: db LAe q: db 8: 2 8: AM 8: 2 8:45 AM 8:2 8:5 AM 8:2 8:5 5AM 8: 29: AM 8 :29: 5A M8:29: A M 5/1 7/ X: 9:13:18 AM - 9:13:51 AM LAeq: 81.3 db X: 9:13:38 AM - 9:13:39 AM LAFmax: 92.7 db LAFmin: 87.2 db LCpeak: 6.3 db LAeq: 91.2 db 9:13:2 AM 9:13:25 AM 9:13:3 AM 9:13:35 AM 9:13: AM 9:13:45 AM 9:13: AM 1 X: 9:16:32 AM - 9:16:52 AM LAeq: 83.7 db X: 9:16:39 AM - 9:16: AM LAFmax: 93. db LAFmin: 88.1 db LCpeak: 6.2 db LAeq: 91.7 db 9:16:35 AM 9:16: AM 9:16:45 AM 9:16: AM 1 X: 9:19:22 AM - 9:19:55 AM LAeq: 81.1 db X: 9:19:42 AM - 9:19:43 AM LAFmax: 91.1 db LAFmin: 89.1 db LCpeak: 4.3 db LAeq:.2 db 9:19:25 AM 9:19:3 AM 9:19:35 AM 9:19: AM 9:19:45 AM 9:19: AM 9:19:55 AM Figure. Time histories of LAFmax, LAFmin, LCpeak and LAeq for the level flight at feet (33 direction); microphone #1; events, 11 and 12 in table P age

14 Sou nd Cur sor valu es Rep or t X: 8 :28 :38 AM - 8: 2 9:13 AM LAe q: 6 9. db Log ged X: 8 :28 :57 AM - 8: 2 8:58 AM LAF max : 76.8 db LAF mi n: db LCp eak: db LAe q: db 8: 28:4 AM 8: 28:4 5 AM 8: 28:5 AM 8 :28: 5A M8:29: A M 8 : 29:5 AM8:29: AM 5 /17/ 216 X: :33:26 AM - :34:1 AM LAeq: 76.6 db X: :33: AM - :33:51 AM LAFmax: 84.3 db LAFmin: 82.1 db LCpeak: 96.2 db LAeq: 83.1 db :33:3 AM :33:36 AM :33:42 AM :33:48 AM :33:54 AM :34: AM X: :36: AM - :37:16 AM LAeq: 75.4 db X: :36:59 AM - :37: AM LAFmax: 84.9 db LAFmin: 76. db LCpeak: 96.9 db LAeq: 81.1 db :36:42 AM :36:48 AM :36:54 AM :37: AM :37:6 AM :37:12 AM X: ::4 AM - ::41 AM LAeq: 77.3 db X: ::25 AM - ::26 AM LAFmax: 85.6 db LAFmin: 83.2 db LCpeak: 99.4 db LAeq: 84.6 db ::6 AM ::12 AM ::18 AM ::24 AM ::3 AM ::36 AM Figure 11. Time histories of LAFmax, LAFmin, LCpeak and LAeq for the level flight at feet (33 direction); microphone #2; events 7, 8 and 9 in table P age

15 Sou nd Cur sor valu es Rep or t X: 8 :28 :38 AM - 8: 2 9:13 AM LAe q: 6 9. db Log ged X: 8 :28 :57 AM - 8: 2 8:58 AM LAF max : 76.8 db LAF mi n: db LCp eak: db LAe q: db 8: 28:4 AM 8: 28:4 5 AM 8: 28:5 AM 8 :28: 5A M8:29: A M 8 : 29:5 AM8:29: AM 5 /17/ 216 X: :44:49 AM - :45:19 AM LAeq: 76.9 db X: :44:59 AM - :45: AM LAFmax: 85.7 db LAFmin: 81.8 db LCpeak: 98.6 db LAeq: 84.6 db :44: AM :44:55 AM :45: AM :45:5 AM :45: AM :45:15 AM X: :47: AM - :48:21 AM LAeq: 76.8 db X: :48:1 AM - :48:2 AM LAFmax: 85.6 db LAFmin: 83.6 db LCpeak: 98.7 db LAeq: 84.9 db :47: AM :48: AM :48: AM :48:2 AM X: ::58 AM - :51:26 AM LAeq: 76.3 db X: :51:8 AM - :51:9 AM LAFmax: 85. db LAFmin: 81.7 db LCpeak: 97.5 db LAeq: 84.1 db :51: AM :51: AM :51:2 AM Figure 12. Time histories of LAFmax, LAFmin, LCpeak and LAeq for the level flight at feet (1 direction); microphone #2; events, 11 and 12 in table P age

16 a) b) c) d) e) f) Figure 13. Spectra of for the level flight at 2 feet, for different times and for microphone #1: a) event 1; b) event 2; c) event 3; d) event 4; e) event 5; f) event 6 (see table 3). In the legend,,,,,, and represent different times, 5 seconds apart from each other. 16 P age

17 a) b) c) d) e) f) Figure 14. Spectra of for the level flight at feet, for different times and for microphone #1: a) event 7; b) event 8; c) event 9; d) event ; e) event 11; f) event 12 (see table 3). In the legend,,,,,, and represent different times, 5 seconds apart from each other. 17 P age

18 a) b) c) d) e) f) Figure 15. Spectra of for the level flight at 2 feet, for different times and for microphone #2: a) event 1; b) event 2; c) event 3; d) event 4; e) event 5; f) event 6 (see table 3). In the legend,,,,,, and represent different times, 5 seconds apart from each other. 18 P age

19 a) b) c) d) e) f) Figure 16. Spectra of for the level flight at feet, for different times and for microphone #2: a) event 7; b) event 8; c) event 9; d) event ; e) event 11; f) event 12 (see table 3). In the legend,,,,,, and represent different times, 5 seconds apart from each other. 19 P age

20 Appendix A LAeq : A-weighted, equivalent sound level. A widely used noise parameter describing a sound level with the same Energy content as the varying acoustic signal measured LAFmax : A-weighted, Fast, Maximum, Level. LAFmin : A-weighted, Fast, Minimum, Level. LASmax : A-weighted, Slow, Maximum, Level. LASmin : A-weighted, Slow, Minimum, Level. LCpeak : C-weighted, Peak, Level. A-weighting : the A-weighting filter covers the full audio range - 2 Hz to 2 khz and the shape is similar to the response of the human ear at the lower levels - see the Equal Loudness Contours entry. C-weighting : a standard weighting for sound level meters, commonly used for higher level measurements and Peak - Pressure Levels. Approximately follows the Phon curve - also written as db(c) or dbc. Appendix B Microphone #1, low altitude (all noise data in db) Height LAFTeq LAFmax LASmax LAImax LCFmax LCSmax LCImax LAFmin LASmin LAImin LCFmin LCSmin LCImin LCpeak LAIeq LCIeq P age

21 LAeq Microphone #1, high altitude (all noise data in db) Height LAFTeq LAFmax LASmax LAImax LCFmax LCSmax LCImax LAFmin LASmin LAImin LCFmin LCSmin LCImin LCpeak LAIeq LCIeq LAeq Microphone #2, low altitude (all noise data in db) Height LAFTeq LAFmax LASmax LAImax LCFmax LCSmax LCImax LAFmin LASmin LAImin LCFmin LCSmin LCImin LCpeak LAIeq P age

22 LCIeq LAeq Microphone #2, high altitude (all noise data in db) Height LAFTeq LAFmax LASmax LAImax LCFmax LCSmax LCImax LAFmin LASmin LAImin LCFmin LCSmin LCImin LCpeak LAIeq LCIeq LAeq P age

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