Supersonic Commercial Aircraft Research Articles

Impact of reduced sonic boom exposure on psychophysical and cognitive performance for simulated booms presented in a realistic indoor environment

This study aimed to quantify, in situations representative of the daily life of European citizens, the effects of sonic boom exposure on human responses, in the case of a new generation of supersonic commercial aircraft that should emit a reduced (compared to the past generation like Concorde) but perceivable boom while flying overland. Two reduced boom simulators were affixed to the bedrooms’ windows of a house located on our university campus. The simulators were used to study indoor the participants’ responses to realistic “outdoor” booms. Testing took place in both the living room and kitchen because the booms caused different intensities of rattle noise in those two rooms. Participants performed various tasks (communication, working memory, drawing, valence evaluation), took three mandatory rests and filled in various questionnaires about the annoyance caused by the booms and their mood. This paper focuses on the psychophysical and cognitive performance results. The booms resulted in delayed responses in the working memory task and in the valence evaluation task, and in a momentary slowing down in the drawing task. There was no significant effect in the communication task, even though a trend for a worsening of communication efficiency was observed. Taken together, the results suggest that reduced booms can interfere with cognitive and motor tasks by capturing attention, which can momentarily divert cognitive resources away from the task at hand. These results suggest future research directions and may lead to recommendations for future sonic boom regulations.

Evaluation of feasibility of commercial supersonic flight based on aeroacoustics

The drive to attain ever higher speeds, to be able to travel ever faster fuels the research and development for a commercial supersonic aircraft. This has previously led to the Concorde which travelled at more than twice the speed of sound. Now, in addition to business considerations about economic viability, supersonic aircraft must be quieter and emit less emissions. Considering the 20 years that have elapsed since Concordes retirement, this study aims to reevaluate the current challenges and limitations to achieving commercial supersonic flight again, in the context of noise. Identifying sonic booms and jet exhaust noise as two main challenges, it reviews current shape optimization methods, plasma as a sonic boom mitigator, sonic boom circumvention, chevron nozzles, variable cycle engines, engine positioning, and their corresponding limitations. Some of the methods have been refined for use and application in final stage design and manufacture of certain supersonic aircraft which indicates a certain feasibility.

Experimental Characterization of Supersonic Diamond Jet Acoustics

Acoustic emissions from supersonic jets are of interest due to their deleterious effects on nearby personnel and structures. As development of both military and commercial supersonic aircraft continues to grow, it is essential to combat increasing noise pollution. Axisymmetric jets are highly prevalent where their aeroacoustic characteristics have been well-documented; in contrast, relatively few studies have examined non-axisymmetric jets. In the present study, aeroacoustics of supersonic jets produced by a diamond-shaped Mach 2 nozzle are explored across a large operational envelope under different pressure ratios ranging from highly overexpanded to moderately underexpanded. Measurements of the far-field acoustics in an anechoic environment were used to characterize the acoustic flowfield and contrast the distribution of energy in the spectral domain between the characteristic major and minor axes of the nozzle. Overall, the diamond jet exhibits a highly directional acoustic field with a distinct local minimum for sideline noise. Furthermore, screech behavior was only observed in a narrow, overexpanded flow regime; this is in contrast to the documented behavior of axisymmetric and rectangular jets. Over the conditions examined there is no indication of distinct staging. Additionally, there exists a nozzle pressure ratio threshold beyond which peak noise switches axes.

A Rapid Surrogate Model for Estimating Aviation Noise Impact across Various Departure Profiles and Operating Conditions

Aviation noise remains a key barrier to the sustainable growth of commercial aviation. The advent of emerging technologies, such as urban air mobility, and the renewed interest in commercial supersonic transport aircraft, has only further raised concerns over the resultant community noise exposure. The foundation of any noise mitigation effort is the ability to accurately model noise metrics over a wide range of scenarios. Aviation noise is influenced by a wide variety of factors, including aircraft type, payload weight, thrust settings, airport elevation, ambient weather, and flight trajectory. Traditional noise modeling paradigms rely on physics-based and empirical calculations, which are computationally expensive. Attempts at speeding up the computations with alternate models could deliver on speed or accuracy, but not both. Recent research has indicated that model order reduction techniques hold promise for transforming and greatly reducing the number of quantities that need to be modeled. Paired with surrogate modeling techniques, a rapid and accurate noise model can be generated. The research presented in this manuscript expands on the model order reduction method and develops a rapid noise surrogate model, which can account for the piloting actions, the ambient temperature, and airport elevation. The presented results indicate that the method works well with minimal error for most modeling scenarios. The results also outline avenues for improvement, such as using a different class of surrogate models or modeling additional training cases. The model developed in this research has numerous applications for multi-query applications, such as parametric trade-off analyses and optimization studies. With the inclusion of airport and aircraft parameters, the model enables the development of frameworks that optimize piloting actions for noise mitigation on the ground.

Potential Impacts on Ozone and Climate From a Proposed Fleet of Supersonic Aircraft

AbstractThere has been renewed interest in developing commercial supersonic transport aircraft due to the increased overall demands by the public for air travel, the aspiration for more intercontinental travel, and the desire for shorter flight times. Various companies and academic institutions have been actively considering the designs of such supersonic aircraft. As these new designs are developed, the environmental impact on ozone and climate of these fleets need to be explored. This study examines one such proposed commercial supersonic fleet of 55‐seater that is projected to fly at Mach 2.2, corresponding to cruise altitudes of 17–20 km, and which would burn 122.32 Tg of fuel and emit 1.78 Tg of NOx each year. Our analyses indicate this proposed fleet would cause a 0.74% reduction in global column ozone (∼2 Dobson Units), which is mainly attributed to the large amounts of nitrogen oxides released in the atmosphere from the supersonic aircraft. The maximum ozone loss occurs at the tropics in the fall season, with a reduction of −1.4% in the total column ozone regionally. The stratospheric‐adjusted radiative forcing on climate from this fleet was derived based on changes in atmospheric concentrations of ozone (59.5 mW/m2), water vapor (10.1 mW/m2), black carbon (−3.9 mW/m2) and sulfate aerosols (−20.3 mW/m2), resulting in a net non‐CO2, non‐contrail forcing of 45.4 mW/m2, indicating an overall warming effect.

A history of jet noise research at the National Aeronautics and Space Administration.

This paper reviews jet noise research conducted at the National Aeronautics and Space Administration (NASA) from the early 1950s to the present day. Research conducted by NASA's predecessor, the National Advisory Committee for Aeronautics (NACA), and during the early years of NASA focused on turbojet noise, where a common approach for reducing jet noise was to limit the jet exit velocity to speeds that provided acceptable noise levels. Suppressors tested during this time resulted in thrust losses that were too severe to be implemented. With the introduction of turbofan engines in the 1960s, NASA shifted research to programs for both subsonic and supersonic aircraft applications with specific noise reduction goals. Subsonic research focused on increasing the bypass ratio of the engine to reduce the jet exit velocity of the core exhaust and adding mixers to the dual exhaust streams. Advances in computational methods improved aerodynamic designs and jet noise prediction tools. Supersonic applications proved to be more troublesome as programs aimed at large commercial transports required higher specific thrust engines. Changing the engine cycle to reduce jet noise was not compatible with mission range and speed requirements. Research for supersonic commercial aircraft remains an area of interest today at NASA.

Impact of low sonic boom exposure on psychophysical and cognitive performance

The RUMBLE project aimed to quantify the effects of low sonic boom exposure on human responses, in situations representative of the daily life of European citizens, so as to inform policy, establish standards and develop protection concepts for a new generation of supersonic commercial aircraft that should emit a reduced but perceivable boom (a “low boom”) while flying overland. Two low boom simulators were affixed to the bedrooms’ windows of a house located on our university campus. The simulators allowed us to study indoor the participants’ responses to realistic “outdoor” booms. Testing took place in both the living room and kitchen because the booms caused different intensities of rattle noise in those two rooms. Participants performed a communication task, a working memory task, a drawing task, and an automatic evaluation task. They also had three mandatory rests. We used questionnaires to assess the booms’ perception and annoyance as well as their influence on participants’ mood. The booms were rated unpleasant, especially with rattle, and more disturbing during the rests than during the tasks. The booms made the rests less relaxing and impaired short-term cognitive performance. [This research was conducted as a part of Rumble—EU Grant Agreement 769896.]

Estimating supersonic commercial aircraft market and resulting CO$$_2$$ emissions using public movement data

Estimating supersonic commercial aircraft market and resulting CO$$_2$$ emissions using public movement data

Sustainability: key to enable next generation supersonic passenger flight

The 2020 global Covid-19 pandemic has shocked the aviation system to its core, showcasing what the loss of this economic engine can do to the world’s economies and societies. This crisis also presents an opportunity to create new capabilities and outlooks. Commercial supersonic flight is one such capability. The availability of advanced computational designs and propulsion systems, new materials, route optimization and alternative fuels means that supersonic aviation can be part of that future in a sustainable manner.Boom’s ultimate goal is to mainstream supersonic air travel and make it accessible to millions of passengers per year. Long-term projections of business-class airline demand suggest a total market of 1,000 to 2,000 commercial supersonic aircraft operating on more than 500 primarily transoceanic routes that will benefit from speeds twice as fast as today’s aircraft.Given the increased focus on mitigating aviation’s environmental impact, bringing a new aircraft to market in the 2020s requires a careful focus on sustainability. To ensure public acceptance supersonic aircraft manufacturers and operators will have to proactively engage with stakeholders to address their concerns and focus on integrating sustainability solutions across their business strategies.Boom is the first commercial aviation OEM to build sustainability into its aircraft programmes from day one, ensuring that sustainability considerations form an integral part of every aspect of the production process. A sustainability commitment to cover every step in the aircraft development cycle, from design and test through in-service operations and end-of-life recycling is key to successfully reintroduce commercial supersonic flight in the years ahead.

Modelling performance an air transport network operated by subsonic and supersonic aircraft

ABSTRACTThis paper deals with modelling the performance of an air transport network operated by existing subsonic and the prospective supersonic commercial aircraft. Analytical models of indicators of the infrastructural, technical/technological, operational, economic, environmental, and social performance of the network relevant for the main actors/stakeholders involved are developed. The models are applied to the given long-haul air route network exclusively operated by subsonic and supersonic aircraft according to the specified “what-if” scenarios.The results from application of the models indicate that supersonic flights powered by LH2 (Liquid Hydrogen) could be more feasible than their subsonic counterparts powered by Jet A fuel, in terms of about three times higher technical productivity, 46% smaller size of the required fleet given the frequency of a single flight per day, 20% lower sum of the aircraft/airline operational, air passenger time, and considered external costs, up to two times higher overall social-economic feasibility, and 94% greater savings in contribution to global warming and climate change. These flights could be less feasible in terms of about 70-85% higher aircraft/airline operational costs, 70% and 19% higher fuel consumption and emissions of Green House Gases, respectively, and 6-13% higher noise compared to the specified acceptable levels.

About Supersonic Flight and Mach 3 Flying

Aerospace-BAC Concorde was a supersonic passenger aircraft. It was the result of a government treaty between the French and British governments, combining the efforts of Aerospace and British Aircraft Corporation. With only 20 aircraft built in total, the cost of the development phase was a major economic failure. In addition, Air France and British Airways were subsidized by the government to buy the aircraft. Of the commercial supersonic aircraft, Concorde was the most successful, with the Tupolev Tu-144 being the other aircraft. The Tu-144 had a higher top speed, but the consumption was higher and the autonomy was lower than the Concorde. Flying for the first time in 1969, Concorde began its commercial service in 1976 and continued for 27 years. It operated transatlantic flights from Heathrow, London (British Airways) and Charles de Gaulle, Paris (Air France) to JFK, New York and Dulles, Washington; flying at record speeds, it travels these distances in less than half the time of other planes. Concorde also set other records, including the official FAI world record "Westbound Around the World" and "Eastbound Around the World" at speed. Following the sole accident on 25 July 2000, the economic effects following the events of 11 September 2001 and other factors, the flights ceased on 24 October 2003. The last flight took place on 24 November of the same year. Many of the problems were overcome during the research and development of the Concorde project. During the flight, the fuel was moved to optimally position the center of gravity relative to the center of pressure at a certain phase of the flight: At subsonic speeds in front, at supersonic speeds in the rear. The shape of the wings was designed to reduce the effect of this change in forces. A very important feature was its maneuverability. Concorde had the characteristics of a fighter jet that could decelerate very quickly from Mach 1.9 to Mach 0.7 in 20 sec. Concorde was so flexible that in extreme cases he could avoid avoidance. A single accident to the fastest, safest and best aircraft in human history has led to its decommissioning and the slowdown of Mach programs. However, after a certain period, these supersonic programs were resumed all over the world because the need for modern, fast flights was growing, the requirements were also more pressing. Supersonic aerodynamics are simpler than subsonic aerodynamics because air sheets at different points along the plane cannot affect each other. Supersonic jets and rocket vehicles require several times more traction to fire through the additional aerodynamic traction experienced in the transonic region (around Mach 0.85-1.2). At these speeds, aerospace engineers can easily guide the air around the aircraft's fuselage without producing new shock waves, but any change in the transverse area away from the vehicle leads to shock waves throughout the body. Designers use the supersonic surface rule and the Whitcomb area rule to minimize sudden changes in size.

An examination of the variations in estimated models for predicting annoyance due to supersonic aircraft noise

There is a need for good criteria to evaluate the acoustic outcomes of designs of future commercial supersonic aircraft. Such criteria could be used with sound predictions to assess impact on communities under flight paths of supersonic aircraft. While surveys of communities exposed to supersonic aircraft noise should be part of the criteria development and validation, some candidate models of people’s responses need to be developed to help focus the design of the community tests. While several tests have been conducted, the models proposed to predict annoyance differ. Analysis of response data from several sonic boom subjective tests is presented. Either indoor or outdoor sounds have been used in the tests, and the models are based on metrics from indoor and from outdoor sounds. The effects of the environment in which the people hear the sounds, the signal sets used in the tests and in the analysis, the metrics and types of models used are discussed.

The significance of edge diffraction in sonic boom propagation within urban environments

Advances in aircraft design, computational fluid dynamics, and sonic boom propagation modeling suggest that commercial supersonic aircraft can be designed to produce quiet sonic booms. Driven by these advances the decades-long government ban on overland supersonic commercial air transportation may be lifted. The ban would be replaced with a noise-based certification standard, the development of which requires knowledge of community response to quiet sonic booms. For inner city environments the estimation of community exposure to sonic booms is challenging due to the complex topography created by buildings, the large spatial extent and the required frequency range. Such analyses are currently intractable for traditional wave-based numerical methods such as the Boundary Element Method. Numerical methods based upon geometrical acoustics show promise, however edge diffraction is not inherent in geometrical acoustics and may be significant. This presentation shall discuss an initial investigation into the relative importance of edge diffraction in inner city sound fields caused by sonic booms. Results will provide insight on the degree to which edge diffraction effects are necessary for accurate predictions of inner city community exposure.

Evaluation of the effect of aircraft size on indoor annoyance caused by sonic booms

Sonic booms from recently proposed supersonic aircraft designs developed with advanced tools are predicted to be quieter than those from previous designs. The possibility of developing a low-boom flight demonstration vehicle for conducting community response studies has attracted international interest. These studies would provide data to guide development of a preliminary noise certification standard for commercial supersonic aircraft. An affordable approach to conducting these studies suggests the use of a sub-scale experimental aircraft. Due to the smaller size and weight of the sub-scale vehicle, the resulting sonic boom is expected to contain spectral characteristics that differ from that of a full-scale vehicle. To determine the relevance of using a sub-scale aircraft for community annoyance studies, a laboratory study was conducted to verify that these spectral differences do not significantly affect human response. Indoor annoyance was evaluated for a variety of sonic booms predicted for several different sizes of vehicles. Previously reported results compared indoor annoyance for the different sizes using the metric Perceived Level (PL) at the exterior of the structure. Updated results include analyses with other candidate noise metrics, nonlinear regression, and specific boom duration effects.

A flight research overview of the Waveforms and Sonicboom Perception and Response Project, the National Aeronautics and Space Administration's pilot program for sonic boom community response research

To support the National Aeronautics and Space Administration’s (NASA) ongoing effort to bring supersonic commercial travel to the aerospace industry NASA Dryden, in cooperation with other government and industry organizations, conducted a flight research experiment to identify the methods, tools, and best practices for a large-scale sonic boom community human response test. The name of the project was Waveforms and Sonicboom Perception and Response (WSPR). Such tests go toward building a dataset that governing agencies like the Federal Aviation Administration and International Civil Aviation Organization will use to establish regulations for acceptable sound levels of overland sonic booms. This paper focuses on NASA’s role in the project on essential elements of community response testing including recruitment, survey methods, instrumentation systems, flight planning, and operations. Objectives of the testing included exposing a residential community with sonic boom doses designed to simulate those produced by the next generation of commercial supersonic aircraft. The sonic booms were recorded with an instrumentation array that spanned the community. Human response data was collected using multiple survey methods, and was correlated to acoustic metrics from the sonic booms. The project resulted in lessons-learned and the findings of appropriate methods necessary to implement a successful large-scale test.

Supersonic aircraft: Shake, rattle and role

There has been a renewed interest worldwide to focus on identifying technological advances that could satisfy the production of a new commercial supersonic aircraft. Although advances have been realized since the Concorde was developed, there is widespread agreement that many challenges remain. At a lesser risk, a supersonic business jet (SBJ) is seen as a technological stepping‐stone in the overall tactic of advancing the speed of commercial aircraft. This presentation outlines some of the technological and environmental regulatory challenges facing such an aircraft. This includes a review of the established technical noise working group and activities that address supersonic aircraft environmental matters: sonic boom, aircraft community noise, and aircraft emissions. Federal Aviation Administration (FAA) maintains that a successful supersonic aircraft will depend on its stakeholders’ ability to deal with these key issues. FAA finds it beneficial to work within the international arena for addressing these issues to ensure that all stakeholders’ concerns are considered. Ultimately, successfully addressing concerns regarding sonic boom is a necessary initial condition for regulatory authorities to reconsider existing restrictions on supersonic operations, the key constraint to the business case in the revival to develop a civil supersonic aircraft for the future.

Separating chemistry and transport effects in two‐dimensional models

Representation of transport in numerical models is known to be a major uncertainty in modeling of the atmosphere. Models also differ in their treatment of gas phase and heterogeneous chemistry. This paper will describe a quantitative approach to diagnosing the source of intermodel differences in ozone assessment calculations. Our approach is applied to diagnosing the differences between two‐dimensional (2‐D) models from Atmospheric and Environmental Research, the NASA Goddard Space Flight Center, and the Lawrence Livermore National Laboratory. Surprisingly, we find that differences due to chemical formulation are often as large as those due to transport, despite the fact that all models use the same set of reaction rate coefficients. These differences are particularly large when polar stratospheric cloud (PSC) processes are included in the models, though differences due to photolysis rates and details of the sulfate chemistry are also apparent. Perturbation calculations for a scenario including supersonic commercial aircraft operating in the 2015 stratosphere reveal that differences in the accumulation of H2O and NOy emitted by aircraft are due almost entirely to transport, while differences in ozone due to chemical formulation are evident in the lower stratosphere even without differences in H2O and NOy and without PSCs. By demonstrating a capability of separating transport and chemical differences, it is hoped that the results described in this paper will stimulate analogous studies with other models and will thus lead to a deeper understanding of intermodel similarities and differences, along with a means to quantify uncertainties in model predictions of atmospheric response to perturbations.

2D and 3D aerodynamic shape optimisation using the adjoint approach

The present paper aims at describing the potential of the adjoint technique for aerodynamic shape optimisation. After a brief description of the continuous adjoint formulation and the aerodynamic optimisation process developed at the DLR, specific requirements for an optimisation framework combined with the adjoint technique are introduced. The drag reduction at constant lift and pitching moment for the RAE2822 airfoil in transonic flow is then presented as validation case. An extension to multi-point optimisation demonstrates the capability of the framework to solve more complex problems. Finally, the wing-body optimisation of a supersonic commercial aircraft confirms the flexibility of the framework and the efficiency of the adjoint technique.

“Supersonic Aircraft: Balancing Fast, Affordable, and Green”

There has been a renewed interest worldwide focusing on identifying technological advances, which can allow production and operation of new commercial supersonic aircraft. There is a lot of advancement since the Concorde was developed however many challenges still exist. A supersonic business jet (SBJ) is seen as a technological stepping-stone in the overall challenge of advancing the speed of commercial aircraft. This paper outlines some of the key technological, economic, and environmental challenges facing such an aircraft. Quality of life and health impact environmental issues include sonic boom, aircraft community noise, and aircraft emissions. The authors maintain that a successful supersonic aircraft will depend on our ability to deal with these issues. We suggest that working within an international arena to address these issues is necessary to ensure that all stakeholders' concerns are considered. Ultimately, successfully addressing concerns regarding sonic boom is a necessary condition for regulatory authorities to reconsider the current ban on supersonic fight over land, the key constrain to the business case for future supersonic transports.

Recent aeroacoustics research in the United States

It is expected that with the projected increase in air travel aeroacoustics research will be very critical in meeting increasingly stringent aircraft noise certification standards. In the United States aeroacoustics research has steadily progressed toward enhanced safety, noise benefits and lower costs. This report provides a brief summary of selected recent aeroacoustics activity in the US. Four topics of great interest to the aerospace industry are: (1) Advanced Subsonic Technology (AST) for future subsonic aircraft, (2) High Speed Research (HSR) for future supersonic commercial aircraft, (3) Rotorcraft noise control efforts, and (4) Weapons bay and other noise control applications for the military. Examples of good progress in the areas of jet, fan, airframe and helicopter noise as well as liner design and weapons bay noise suppression are provided herein. In the next few years we look forward to seeing major strides in noise reduction technology and our ability to predict situations of aeroacoustics i...