2.0 Introduction 2.1 Subject of the Report Research in the area of Advanced Supersonic Transport(AST)has been a focus area for NASA since 1960s,driven by maintaining US leadership in the area of commercial transport.According to a 1980 Open Travel Alliance (OTA)report26 on the impact of advanced air transport technology,the business case in favour of ASTs results from improved aircraft productivity(measured in seat miles generated per unit time)and its capability to transport twice the number of passengers on long distance flight.Higher cost of operations,concerns over environmental impact due to noise and emissions,and restrictions to fly supersonic on land due to sonic boom are some of the technological issues that need to be addressed for production and deployment of ASTs.NASA's research efforts for the advancement of AST are dedicated to address these technical challenges and the AST technology is being matured under N+1,N+2 and N+3 projects.The goal of the N+3 project is to explore a conceptual design for multi-Mach aircraft in 2030 timeframe that has low sonic boom,is environmentally acceptable,fuel efficient,and able to fly at supersonic speed above land.Other,integrated design concerns include: Sonic Boom Reduction Cruise Efficiency Aero-Propulsive-Servo-Elasticity Airport Noise Light Weight Structure for Airframe/Propulsion Systems High Altitude Emissions A complimentary area for NASA research is the Next Generation Air Transportation System (NextGen)(Joint Planning and Development Office,2009).The U.S.Air Traffic Management(ATM)system is today operating at the edge of its capabilities, handling the real-time planning and coordination of over 50,000 flights per day.Although air traffic has seen a decline in the recent year due to severe economic downturn,the recent numbers suggest that traffic is currently stabilizing(Official Airline Guide,2009)however,per market forecasts by MITRE23 and Boeing16(2009)a strong growth in air traffic is expected in both short and long term.Additionally,Boeing's long term market forecast cites that the air transportation industry is resilient and has survived many economic downturns in the past.It has grown at 5%annually and by year 2029 the number of airplanes flying in the National Air Space will be more than double.To address this concern,the Federal Aviation Administration (FAA) along with NASA and other government and industry partners are charting the NextGen. One of the strategic objectives outlined in the NextGen plan is to have a system scalable enough to respond quickly and efficiently to increase in demand and is flexible enough to incorporate new types of airframe for example,Unmanned Aircraft System(UAS),Very Light Jets(VLJs),Large Civil Tiltrotor(LCTR),ASTs,and others.Since supersonic transports provide a step increase in passenger mobility by speed of travel,their incorporation within the NextGen ATS could potentially provide alternative methods of operation,subsonic to supersonic transition regulations,and unforeseen hazards.NASA is focused on providing vehicle designs and identifying enabling technologies that can meet the nation's need for effective,efficient and safe air travel. Overall,the supersonics project is designed to develop knowledge,capabilities,and identify innovative solutions for supersonic air vehicles.Sonic boom,environmental concerns,and NextGen ATS integration are major concerns for commercial supersonic travel.Revolutionary solutions are required to generate viable,supersonic solutions. 2.2 Purpose The purpose of this paper is to preview and highlight the final report to the NASA sponsored program"N+3 NRA Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2030-2035 Period."The N+3 program is focused on generating promising supersonic concepts for the 2030-2035 timeframe and to develop plans for maturing the technologies required to make those concepts a reality.An additional system-level focus includes understanding how a supersonic civil transport would integrate and operate within the 2035 NextGen ATS. This program is committed to overcoming significant environmental (sonic boom,airport noise,and cruise emission)and performance (cruise speed,range,payload and fuel efficiency)challenges.The NASA stated N+3 goals are illustrated in Table 2.Meeting or surpassing these goals stimulates innovation and advances the pursuit of revolutionary conceptual designs. System-level multi-disciplinary analysis and optimization (MDAO)and out-of-the-box thinking allows for revolutionary technology identification.This fosters an environment of innovation and generates excitement for future supersonic travel. Overall,the N+3 effort is driven by the need for alternative solutions capable of overcoming the efficiency,environmental,and performance barriers to practical supersonic flight.Results from these studies aid in upcoming research efforts and provides a roadmap for future supersonic funding. Copyright 2010 by Lockheed Martin,Published by the American Institute of Aeronautics and Astronautics,Inc.,with permission.Copyright 2010 by Lockheed Martin, Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. 4 2.0 Introduction 2.1 Subject of the Report Research in the area of Advanced Supersonic Transport (AST) has been a focus area for NASA since 1960s, driven by maintaining US leadership in the area of commercial transport. According to a 1980 Open Travel Alliance (OTA) report26 on the impact of advanced air transport technology, the business case in favour of ASTs results from improved aircraft productivity (measured in seat miles generated per unit time) and its capability to transport twice the number of passengers on long distance flight. Higher cost of operations, concerns over environmental impact due to noise and emissions, and restrictions to fly supersonic on land due to sonic boom are some of the technological issues that need to be addressed for production and deployment of ASTs. NASA‘s research efforts for the advancement of AST are dedicated to address these technical challenges and the AST technology is being matured under N+1, N+2 and N+3 projects. The goal of the N+3 project is to explore a conceptual design for multi-Mach aircraft in 2030 timeframe that has low sonic boom, is environmentally acceptable, fuel efficient, and able to fly at supersonic speed above land. Other, integrated design concerns include: • Sonic Boom Reduction • Cruise Efficiency • Aero-Propulsive-Servo-Elasticity • Airport Noise • Light Weight Structure for Airframe/Propulsion Systems • High Altitude Emissions A complimentary area for NASA research is the Next Generation Air Transportation System (NextGen) (Joint Planning and Development Office, 2009). The U.S. Air Traffic Management (ATM) system is today operating at the edge of its capabilities, handling the real-time planning and coordination of over 50,000 flights per day. Although air traffic has seen a decline in the recent year due to severe economic downturn, the recent numbers suggest that traffic is currently stabilizing (Official Airline Guide, 2009) however, per market forecasts by MITRE23 and Boeing16 (2009) a strong growth in air traffic is expected in both short and long term. Additionally, Boeing‘s long term market forecast cites that the air transportation industry is resilient and has survived many economic downturns in the past. It has grown at 5% annually and by year 2029 the number of airplanes flying in the National Air Space will be more than double. To address this concern, the Federal Aviation Administration (FAA) along with NASA and other government and industry partners are charting the NextGen. One of the strategic objectives outlined in the NextGen plan is to have a system scalable enough to respond quickly and efficiently to increase in demand and is flexible enough to incorporate new types of airframe for example, Unmanned Aircraft System (UAS), Very Light Jets (VLJs), Large Civil Tiltrotor (LCTR), ASTs, and others. Since supersonic transports provide a step increase in passenger mobility by speed of travel, their incorporation within the NextGen ATS could potentially provide alternative methods of operation, subsonic to supersonic transition regulations, and unforeseen hazards. NASA is focused on providing vehicle designs and identifying enabling technologies that can meet the nation‘s need for effective, efficient and safe air travel. Overall, the supersonics project is designed to develop knowledge, capabilities, and identify innovative solutions for supersonic air vehicles. Sonic boom, environmental concerns, and NextGen ATS integration are major concerns for commercial supersonic travel. Revolutionary solutions are required to generate viable, supersonic solutions. 2.2 Purpose The purpose of this paper is to preview and highlight the final report to the NASA sponsored program ―N+3 NRA Advanced Concept Studies for Supersonic Commercial Transports Entering Service in the 2030-2035 Period.‖ The N+3 program is focused on generating promising supersonic concepts for the 2030-2035 timeframe and to develop plans for maturing the technologies required to make those concepts a reality. An additional system-level focus includes understanding how a supersonic civil transport would integrate and operate within the 2035 NextGen ATS. This program is committed to overcoming significant environmental (sonic boom, airport noise, and cruise emission) and performance (cruise speed, range, payload and fuel efficiency) challenges. The NASA stated N+3 goals are illustrated in Table 2. Meeting or surpassing these goals stimulates innovation and advances the pursuit of revolutionary conceptual designs. System-level multi-disciplinary analysis and optimization (MDAO) and out-of-the-box thinking allows for revolutionary technology identification. This fosters an environment of innovation and generates excitement for future supersonic travel. Overall, the N+3 effort is driven by the need for alternative solutions capable of overcoming the efficiency, environmental, and performance barriers to practical supersonic flight. Results from these studies aid in upcoming research efforts and provides a roadmap for future supersonic funding