Commercial Space Operations Noise and Sonic Boom Modeling and Analysis (2018)

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5-1 CHAPTER 5. Approval Process for Commercial Space Noise Studies The FAA Office of Environment and Energy (AEE) has approved models for detailed noise analysis. Prior written approval from AEE is required to use another equivalent methodology or computer model. Modification to standard or default data also requires prior written approval from AEE. PCBoom has been designated an approved modeling method by AEE for sonic boom analysis of commercial space operations [FAA, 2015]. As of May 2017, RUMBLE has not been designated as an approved model by AEE, and thus written approval from AEE is required when using RUMBLE. The most current version of FAA’s 1050 desk reference should be consulted to confirm the list of FAA-approved models for detailed noise analysis. Additionally, review and approval of the use of non-default modeling data may be required, such as user-defined vehicles, trajectories, and atmospheric profiles. The approval of particular non-default methods or data in past studies does not guarantee approval in a future study. Each modeling situation is unique and must be evaluated on a case-by-case basis. This section provides guidance that could be used to develop an official approval process to conduct reviews of modeling methodology and input data used in the RUMBLE and PCBoom models. The guidance also addresses the essential components of the review package that project consultants must submit to AST for review. The review process is a quality control check on the modeling inputs and methodologies used for environmental assessment of space operations. The guidance presented here is similar to the review and approval process that FAA uses for commercial airport noise studies [FAA, 2016], but it is tailored specifically for the RUMBLE and PCBoom models. Note that the information presented here is not the official AEE internal review and approval process, but could be used in the development of instructions. Section 5.1 describes procedures for requesting AEE review of non-default methods and data, Section 5.2 provides a list of common data and whether review and approval may be required, and Section 5.3 provides guidance regarding information to submit for AEE review of non-default methods and data. 5.1. Procedures for AEE Review of Non-Default Methods and Data Below is a description of the required steps for AEE review and approval to use non-default methods and data.  Initial communication between the project consultant (PC), in coordination with the project sponsor (PS), and FAA project manager (PM) in the region, district office, or service center to determine if the proposed non-default methods/data require formal review by AEE. As part of this discussion, the PC should be prepared to explain the reason for the use of non-default methods/data to the PM and AEE.  The PC must then submit a review package to AST, in coordination with the PS and PM. Information in the review package must be complete and presented in a clear manner. The information and the review process must be well-documented and may be included as an appendix to an EA, EIS, or study report as part of the NEPA documentation. The format of the review package is described in Section 5.3.  After receiving the review package and checking it for completeness, AST-100 will forward the review package to AEE.  Provided the review package is complete and contains all essential information (see Section 5.3), AEE will begin their review of the package. During the review period, AEE may discuss the

5-2 review package, gather more facts, and clarify the technical issues directly with the PC. Unless policy implications or substantive issues arise, AEE does not need to coordinate with other FAA headquarters offices or the PM during this period, other than providing emails on the status of its review, as appropriate.  AEE will prepare a letter addressed to the PM providing the decision on the review package.  AEE will forward the decision letter to the PM (with a cc: AST-100) by email. The PM should convey the decision to the PS and PC.  If AEE approves the use of non-default methods or data, the following must be included in the FAA’s project file: (1) a copy of AEE’s approval letter; and (2) a description of the approved non-default method(s) and/or data. Questions about the above procedures should be addressed to AST-100, whether the questions pertain to the process or as applied to a specific project. Early and clear communications by the PC will reduce the chance of delay caused by an incomplete review package. 5.2. List of Common Methods/Data and Review Requirements Sections 5.2.1 and 5.2.2 describe common data used to model commercial space operations. For information on how to request changes to methods or data not listed in either section, please contact AEE. 5.2.1. Analysis Methods/Data that Do Not Require AEE Review and Approval The following analysis methods or data are recommended to not require AEE review and approval: Default methods and data that are provided in RUMBLE or PCBoom. Trajectory information that is provided by a spacecraft manufacturer. Data may require custom editing by the user to smooth out spurious or irregular data. Therefore, it is recommended that users compare any modified trajectory data with the original data to make sure that the modified version retains the important features of the original trajectory. Use of the US Standard Atmosphere model [NASA and U.S. Air Force, 1976], with altitude extensions, or any atmosphere model native to RUMBLE or PCBoom would not require review and approval. Use of supplemental (i.e. other than DNL) noise metrics that are native to RUMBLE and PCBoom, provided that the study only reports the resulting noise levels and does not draw any specific conclusions about impacts or suggest that the impacts are significant. Conversely, the discussion must include effective language about existing scientific uncertainties and assessment methodology, impact criteria, and policy guidance in the area examined by supplemental metrics. Although the above methods/data do not require approval, they should be well documented in the NEPA documentation. 5.2.2. Analysis Methods/Data that Do Require AEE Review and Approval The following analysis methods or data are recommended to require AEE review and approval.  Sensitivity

5-3   o Any supplemental noise analysis that involves impacts that are likely to be highly controversial on environmental grounds. o Any supplemental noise analysis that involves Section 4(f) properties (including, but not limited to, noise-sensitive areas within national parks; national wildlife and waterfowl refuges; and historic sites including traditional cultural properties) where a quiet setting is a generally recognized purpose and attribute.  Supplemental Noise Metrics o Noise metrics that are not native to RUMBLE or PCBoom. o Interpretation of impacts or significance for supplemental noise metrics that are listed in the 1050.1F Desk Reference. o Supplemental noise analysis that is focused on one or more secondary or indirect effects (e.g. sleep disturbance, health effects, classroom learning, low frequency impacts), regardless of the supplemental metric(s) used.  Spacecraft and Trajectories o Spacecraft that are not native to RUMBLE or PCBoom. o User-defined trajectories not provided by a spacecraft manufacturer.  Non-default weather data used for the analysis of noise.  Alternative models and methodologies that are not native to RUMBLE or PCBoom. 5.3. Guidance Regarding a Request to Use Non-Default Methods/Data The following information is always required for any request to use non-default methods or data: 1. Background. Briefly describe the project, including location, for which non-default methods or data are needed. State the type of analysis (e.g. EA, EIS, or other type of NEPA analysis). Include any additional relevant information. 2. Statement of Benefit. Briefly describe why the non-default methods or data are needed for this project, how the non-default methods or data are more appropriate, and why the default method or data are not sufficient. The sections below discuss the additional RUMBLE and PCBoom specific information required to be submitted for specific types of non-default methods or data. 5.3.1. Non-Standard Rumble Input Data Review RUMBLE allows for the creation of user-defined spacecraft vehicles, trajectories and atmospheric data that differ from default data provided in RUMBLE. If analysts use non-default user-defined spacecraft, trajectories, and/or atmospheric profiles that are not native to RUMBLE for noise analyses, AEE approval is required (see Section 5.2.2). Additional information to include in a submittal package requesting AEE approval for use of user- defined spacecraft, trajectories, or atmospheric profiles are as follows: 1. Spacecraft Information. (If the spacecraft includes more than one engine definition, specify the core/booster engine configuration used.)  Airframe

5-4   o Model and Manufacturer  Engine o Model and Manufacturer o Number of Engines o Number of Nozzles per Engine o Engine Nozzle Exit Diameter (feet) o Engine Nozzle Exit Velocity (feet/second) o Engine Thrust (lbf)  Source Directivity Index 2. Trajectory Information  Time  Latitude and Longitude (degrees)  Altitude (feet MSL)  Speed (feet/second)  Flight Path Heading (degrees)  Flight Path Angle (degrees)  Vehicle Heading (degrees)  Vehicle Pitch (degrees)  Thrust* (lbf) 3. Atmospheric Profile Information  Altitude (feet MSL)  Temperature (degrees Fahrenheit)  Pressure (in Hg)  Humidity (%)  Sounds Speed (feet/second) *optional parameter 5.3.2. Non-Standard PCBoom Input Data Review PCBoom allows for the creation of user-defined spacecraft vehicles, trajectories and atmospheric data that differ from default data provided in PCBoom. If analysts use non-default user-defined spacecraft, trajectories, and/or atmospheric profiles that are not native to PCBoom for noise analyses, AEE approval is required (see Section 5.2.2). Additional information to include in a submittal package requesting AEE approval for use of user-defined launch site (location) data, sonic boom signature/spacecraft input data, trajectories, or atmospheric profiles is outlined below. 1. Spacecraft Information (Signature and Vehicle Input Mode)  Thomas input format  Simple F-function  Carlson’s F-function (Mode 3B and Mode 3E are most likely to be used by practitioners) o (Mode 3B) Launch Vehicle Mode – similar to the Basic Carlson F-function Mode, with the additional inputs of vehicle thrust and vehicle plume drag. This

5-5   mode is used to account for the shocks generated from the presence of an under- expanded plume generated by the launch vehicle. o (Mode 3E) Launch Vehicle Database Mode – provides access to predetermined source signatures from a database of launch vehicles. The user may develop new sonic boom source signatures and add these to the database. o Data requirements for Mode 3B and Mode 3E are: o Vehicle Length (feet) o Vehicle Weight (klbs) o Total Thrust (klbf) o Total Plume Drag (klbf) o Vehicle Angle of Attack (degrees) o User-Specified Shape Factor  Tiegerman Blunt Body Reentry Mode (likely to be used by practitioners) o Data requirements are: o Vehicle Length (feet) o Vehicle Weight (klbs) 2. Trajectory Information  Time  Latitude and Longitude (degrees)  Altitude (feet MSL)  Mach Number  Flight Path Heading (degrees)  Flight Path Angle (degrees) o Use of NEWLOAD command additionally requires total vehicle weight, spacecraft length, total vehicle thrust, plume drag, angle of attack, and vehicle shape factor 3. Atmospheric Profile Information  Altitude (feet MSL)  Temperature (degrees Fahrenheit)  Pressure (psf)  Wind Velocity (x-component, feet/second)  Wind Velocity (y-component, feet/second)  Humidity (%)  Atmospheric Pressure at the Ground (psf) The RUMBLE and PCBoom user guides provide additional details about the input data for both models.