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

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ACKNOWLED This work was Research Prog Sciences, Eng COPYRIGHT I Authors herein persons who o Cooperative R purposes. Per FMCSA, FRA, product, metho uses will give a request permis DISCLAIMER The opinions a are not necess or the program The informatio edited by TRB Com S GMENT sponsored by t ram (ACRP), w ineering, and M NFORMATION are responsibl wn the copyrigh esearch Progra mission is give FTA, Office of d, or practice. ppropriate ack sion from CRP nd conclusions arily those of th sponsors. n contained in t . mercia onic Bo Blue Volpe N he Federal Avia hich is adminis edicine. e for the authen t to any previo ms (CRP) gran n with the unde the Assistant Se It is expected th nowledgment o . expressed or im e Transportatio his document w AC Web-Only l Space om Mo Kevi Wyle La Arl Mich Alexan Ridge Resea As Eric ational Tran Cam tion Administra tered by the Tra ticity of their m usly published o ts permission to rstanding that n cretary for Res at those reprod f the source of a plied in this re n Research Bo as taken direct RP Docume Opera deling n A. Bradley boratories, ington, VA ael M. James dria R. Salto rch and Con heville, NC R. Boeker sportation S bridge, MA tion (FAA). It w nsportation Re aterials and for r copyrighted m reproduce ma one of the mate earch and Tec ucing the mate ny reprinted or port are those o ard; the Nation ly from the subm nt 33: tions N and An Inc. n sulting, LLC ystems Cen Contrac as conducted t search Board ( obtaining writte aterial used he terial in this pub rial will be used hnology, PHMS rial in this docu reproduced ma f the researche al Academies o ission of the a oise an alysis ter tor’s Final Rep hrough the Airp TRB) of the Na n permissions f rein. lication for clas to imply TRB, A, or TDC endo ment for educat terial. For oth rs who perform f Sciences, Eng uthor(s). This m d ort for ACRP Pr Submitted ort Cooperative tional Academie rom publishers sroom and not AASHTO, FAA rsement of a p ional and not-fo er uses of the m ed the researc ineering, and M aterial has not oject 02-66 May 2017 s of or -for-profit , FHWA, articular r-profit aterial, h. They edicine; been

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iii  CONTENTS Summary ...................................................................................................................................................... x 1.0 Introduction ........................................................................................................................................ 1-1 1.1 Background ............................................................................................................................ 1-1 1.2 Objectives ............................................................................................................................... 1-4 1.3 Research Overview ................................................................................................................. 1-4 1.3.1 Rocket Noise Model ........................................................................................................ 1-4 1.3.2 Sonic Boom Model .......................................................................................................... 1-5 1.4 Document Organization ......................................................................................................... 1-7 2.0 Technical Reference ........................................................................................................................... 2-1 2.1 Rocket Noise Modeling Methodology ................................................................................... 2-1 2.1.1 Source .............................................................................................................................. 2-2 2.1.1.1 Acoustic Power .......................................................................................................... 2-2 2.1.1.2 Forward Flight Effect ................................................................................................ 2-3 2.1.1.3 Directivity .................................................................................................................. 2-3 2.1.1.4 Doppler Effect ........................................................................................................... 2-4 2.1.2 Propagation ...................................................................................................................... 2-4 2.1.2.1 Geometric Spreading ................................................................................................. 2-4 2.1.2.2 Atmospheric Absorption ........................................................................................... 2-4 2.1.2.3 Ground Interference .................................................................................................. 2-5 2.1.2.4 Receiver ..................................................................................................................... 2-5 2.1.3 Validation......................................................................................................................... 2-5 2.2 Sonic Boom Modeling Methodology ..................................................................................... 2-7 2.2.1 Sonic Boom Background ................................................................................................. 2-7 2.2.1.1 Sonic Boom Ray Patterns .......................................................................................... 2-7 2.2.1.2 Vehicle Source Characteristics ................................................................................ 2-10

iv  2.2.2 Sonic Boom Theory ....................................................................................................... 2-10 2.2.2.1 Sonic Boom Source F-Functions ............................................................................. 2-12 2.2.2.2 Propagation Using Geometrical Acoustics .............................................................. 2-13 2.2.2.3 Signature Aging ....................................................................................................... 2-18 2.2.3 Focal Zones .................................................................................................................... 2-21 2.2.4 Sonic Boom Metrics ...................................................................................................... 2-22 3.0 AEDT Integration Plan ....................................................................................................................... 3-1 3.1 Rocket Noise Model ............................................................................................................... 3-1 3.1.1 Overview .......................................................................................................................... 3-1 3.1.2 Low-Level Integration Demonstration ............................................................................ 3-2 3.1.3 Full Integration Demonstration ........................................................................................ 3-7 3.2 Sonic Boom Model ............................................................................................................... 3-15 3.2.1 Overview ........................................................................................................................ 3-15 3.2.2 Low-Level Integration Demonstration .......................................................................... 3-16 3.2.3 Full Integration Demonstration ...................................................................................... 3-21 4.0 Model Validation Plan ........................................................................................................................ 4-1 4.1 Introduction ............................................................................................................................ 4-1 4.1.1 Validation of Computer Models ...................................................................................... 4-1 4.2 Spaceport Facilities and Types of Commercial Space Flight Operations .............................. 4-2 4.2.1 Spaceport Facilities and Operators .................................................................................. 4-2 4.2.2 Launch and Reentry Operations ....................................................................................... 4-2 4.3 Validation of RUMBLE ......................................................................................................... 4-2 4.3.1 Review of Existing Acoustic Measurement and Supporting Data ................................... 4-3 4.3.2 Conduct Data Collection and Validation Tests ................................................................ 4-3 4.3.3 RUMBLE Validation Tests.............................................................................................. 4-6 4.4 Validation of PCBoom ........................................................................................................... 4-6

v  4.4.1 Review of Existing Sonic Boom Measurement and Supporting Data ............................. 4-7 4.4.2 Conduct Data Collection and Validation Tests ................................................................ 4-7 4.4.3 PCBoom Validation Tests ............................................................................................... 4-9 4.5 Recommendations for Model Improvement ......................................................................... 4-10 5.0 Approval Process Guidance for Commercial Space Noise Studies .................................................... 5-1 5.1 Procedures for AEE Review of Non-Default Methods and Data ........................................... 5-1 5.2 List of Common Methods/Data and Review Requirements ................................................... 5-2 5.2.1 Analysis Methods/Data that Do Not Require AEE Review and Approval ......................... 5-2 5.2.2 Analysis Methods/Data that Do Require AEE Review and Approval ................................ 5-2 5.3 Guidance Regarding a Request to Use Non-Default Methods/Data ....................................... 5-3 5.3.1 Non-Standard Rumble Input Data Review ......................................................................... 5-3 5.3.2 Non-Standard PCBoom Input Data Review ....................................................................... 5-4 6.0 Future Research .................................................................................................................................. 6-1 7.0 References .......................................................................................................................................... 7-1 LIST OF FIGURES AND TABLES LIST OF FIGURES 1-1 U.S. Launch Sites – “Spaceports” ....................................................................................................... 1-1 1-2 Depiction of Falcon 9 first stage reusability ........................................................................................ 1-3 1-3 Falcon 9 launch and landing at Cape Canaveral Air Force Station ..................................................... 1-3 2-1 Conceptual overview of RUMBLE model methodology ......................................................................... 2-2 2-2 Validation of NASA SP-8072’s DSM-1 empirical curves - (left) overall sound power level for various rockets - (right) normalized relative power spectrum ................................................................................ 2-2 2-3 Predicted OASPL with modified DI - the downstream direction of the rocket is 0° and distance is indicated in nozzle diameters (De) ............................................................................................................. 2-3

vi  2-4 Effect of expanding wavefronts (decrease in frequency) that an observer would notice for higher relative speeds of the rocket relative to the observer for: (a) stationary source, (b) source velocity < speed of sound, (c) source velocity = speed of sound, (d) source velocity > speed of sound .............................. 2-4 2-5 Sound propagation near the ground is modeled as the combination of a direct wave (blue) and a reflected wave (red) from the source to the receiver .................................................................................. 2-5 2-6 Measured versus predicted launch vehicle noise exposure levels - (left) SEL values at set distances from the launch pad - (right) Maximum OASPL at set distances from the launch pad ............................. 2-6 2-7 Measured versus predicted launch vehicle noise time histories .......................................................... 2-6 2-8 SpaceShipTwo, “feather down” .......................................................................................................... 2-7 2-9 SpaceShipTwo, “feather up” ............................................................................................................... 2-7 2-10 Sonic boom wave field ...................................................................................................................... 2-8 2-11 Wave versus ray viewpoints .............................................................................................................. 2-8 2-12 Ray curvatures in a real atmosphere .................................................................................................. 2-8 2-13 Ray crossing and convergence in an acceleration-induced focus ...................................................... 2-9 2-14 Isopemp convergence in an acceleration-induced focus .................................................................... 2-9 2-15 Ray cone in level flight ...................................................................................................................... 2-9 2-16 Ray cone in diving flight ................................................................................................................... 2-9 2-17 Logical flow of sonic boom calculations ......................................................................................... 2-11 2-18 F-function approximated as an N-wave, based on shape factor and length ..................................... 2-13 2-19 Carlson’s shape factors for various aircraft types ............................................................................ 2-13 2-20 Schematic of sonic boom propagation along a ray tube .................................................................. 2-14 2-21 Initial ray cone and coordinates ....................................................................................................... 2-14 2-22 Ray tube outlined by four corner rays  and  apart ............................................................... 2-16 2-23 Ellipsoidal Earth and EFG coordinate system ................................................................................. 2-17 2-24 Evolution and steepening of sonic boom signature ......................................................................... 2-18 2-25 Middleton-Carlson aging method .................................................................................................... 2-20 3-1 Conceptual representation of the integration levels ............................................................................ 3-1 3-2 Create new study dialog ...................................................................................................................... 3-3

vii  3-3 Receptor details ................................................................................................................................... 3-3 3-4 Receptor set details .............................................................................................................................. 3-4 3-5 Import metric result ............................................................................................................................. 3-5 3-6 Linear metric results combiner ............................................................................................................ 3-6 3-7 Create new study dialog ...................................................................................................................... 3-7 3-8 Add existing airport dialog .................................................................................................................. 3-8 3-9 Airport/Spaceport layout design panel ................................................................................................ 3-9 3-10 Edit rocket pad ................................................................................................................................... 3-9 3-11 Edit spacecraft trajectory dialog ...................................................................................................... 3-10 3-12 Create spacecraft operation .............................................................................................................. 3-11 3-13 Provide static details ........................................................................................................................ 3-12 3-14 Conceptual representation of the integration levels ......................................................................... 3-16 3-15 Create new study dialog .................................................................................................................. 3-17 3-16 Receptor details ............................................................................................................................... 3-17 3-17 Receptor set details .......................................................................................................................... 3-18 3-18 Import metric result ......................................................................................................................... 3-19 3-19 Linear metric results combiner ........................................................................................................ 3-20 3-20 Create new study dialog .................................................................................................................. 3-21 3-21 Add existing airport/spaceport dialog .............................................................................................. 3-22 3-22 Add existing airport/spaceport layout design panel ......................................................................... 3-23 3-23 Airport/spaceport layout design panel ............................................................................................. 3-23 3-24 Edit spacecraft trajectory dialog ...................................................................................................... 3-24 3-25 Create spacecraft operation .............................................................................................................. 3-25 3-26 Select equipment (vehicle) .............................................................................................................. 3-26 3-27 Create annualization wizard – create spacecraft operation groups step .......................................... 3-27 3-28 Create annualization wizard – build annualization step .................................................................. 3-27

viii  3-29 Receptor details ............................................................................................................................... 3-28 3-30 Receptor set details .......................................................................................................................... 3-28 3-31 Import metric result ......................................................................................................................... 3-29 4-1 Example vertical launch vehicle A-weighted OASPL contours .......................................................... 4-4 4-2 Example horizontal launch vehicle SEL contours ............................................................................... 4-5 4-3 Launch vehicle (ascent to orbital trajectory) sonic boom footprints ................................................... 4-8 4-4 Horizontally launched and horizontally landed vehicle sonic boom footprints .................................. 4-9 LIST OF TABLES 1-1 Active Launch Licenses .............................................................................................................. 1-2

ix  02-22-2018 AUTHOR ACKNOWLEDGMENTS The research team expresses our appreciation to the Airport Cooperative Research Program (ACRP) for undertaking significant research opportunities including ACRP Project 02-66, “Commercial Space Operations Noise and Sonic Boom Modeling and Analysis”. We also express our gratitude to the panel members and liaison members whose efforts were an integral part of the success of Project 02-66. The research team acknowledges the contributions of the late Dr. Kenneth Plotkin, Wyle’s Chief Scientist, who developed the sonic boom prediction model (PCBoom) used in this research. Dr. Plotkin was one of the first to develop models for the noise assessment of spacecraft operations.

x  SUMMARY This document provides an overview of the research performed under Airport Cooperative Research Program (ACRP) Project 02-66 “Commercial Space Operations Noise and Sonic Boom Modeling and Analysis”. Commercial space launch vehicle activities are expected to increase with growth in the number of launch operators and in the emergence of different types of launch vehicles and missions designed to serve space tourism, satellite deployment, and International Space Station (ISS) cargo resupply. The Federal Aviation Administration (FAA) Office of Commercial Space Transportation (AST) regulates the U.S. commercial space transportation industry and part of AST’s mission is to ensure that proposed commercial space operations comply with applicable environmental laws, regulations, and other requirements. Pertaining to noise, this requires that suitable tools are available for the evaluation of noise and sonic boom from these operations. The purpose of this project was to develop rocket noise and sonic boom models for commercial space operations that are compatible with, or can be integrated with the FAA’s Aviation Environmental Design Tool (AEDT). AEDT is a software system that models aircraft fuel consumption, emissions, noise, and air quality consequences. AEDT is a comprehensive tool that provides information to FAA stakeholders on each of these specific environmental impacts and facilitates environmental review activities required under NEPA by consolidating the modeling of these environmental impacts in a single tool. Further objectives of this project were to develop a database of existing vehicle/engine data for commercial space launch operations, develop a model validation plan that can be used to check the accuracy of both models compared to noise measurements of actual space operations, and develop approval process guidance for commercial space noise studies. To meet the objectives of this research, a review was conducted of the of the rocket noise model (RUMBLE) and sonic boom model (PCBoom) to assess the current state of these model’s databases, modeling capabilities, and functionality/usability in order to identify changes required to model current spacecraft operations and for the possible future integration of these models into AEDT. A summary of improvements made to RUMBLE include: development of a database of current spacecraft airframe and engine/motor characteristics; code optimization of some of the computationally intensive parts of the program to significantly decrease run-time; strengthening the model’s compatibility with AEDT including program workflow, model input/output, and database management; and development of a graphic user interface and user guide. A summary of improvements made to PCBoom include: development of a database of vehicle input/sonic boom source characteristics for current spacecraft, increasing the number of noise metrics output for compatibility with AEDT, improved instructions for trajectory post-processing, new noise grid generation capability for AEDT and NMPlot, and a user guide. As part of the development of the rocket noise and sonic boom models, there is a need to conduct comprehensive and systematic model validation studies. A model validation plan was therefore developed to specify the data collection and test requirements needed to validate the rocket noise and sonic boom models. This plan includes general test flight, atmospheric, and noise measurement data requirements to conduct a validation study for RUMBLE and PCBoom. To facilitate review and approval of commercial space environmental noise studies, approval process guidelines were developed that the FAA Office of Environment and Energy (AEE) can use to develop an official approval process to conduct reviews of modeling methodology and input data used in the RUMBLE and PCBoom models. Additional improvements to RUMBLE and PCBoom, to facilitate public use and the integration of these models into AEDT, are presented in this report.