上海交通大学：《飞机设计 Aircraft Design》课程教学资源_参考资料_43_case for small supersonic civil aircraft AIAA-5119-716

JOURNAL OF AIRCRAFT Vol.42.No.3.May-June 2005 Case for Small Supersonic Civil Aircraft Preston A.Henne* Gulfstream Aerospace Corporation,Savannah,Georgia 31402 Civil aviation progress in the last 40 years has included a significant expansion of the small civil aircraft market involving regional jets,business jets,and the emerging personal jets.A significant factor in the growth of the small civil aircraft market is the value of time.Recognition of the ever-increasing value of time has lead to increased interest in the feasibility of a small supersonic civil aircraft.The step to supersonic speeds offers the potential of a dramatic decrease in travel time.Feasibility studies of a small quiet supersonic jet (QSJ)have been conducted. Market research,environmental concerns,program and design requirements,and vehicle characteristics are sum- marized.Areas for concentrated future supersonic aeronautics research and development efforts are highlighted. Introduction York City heading westbound or eastbound and,with one stop,be HE remarkable progress and growth in civil aviation in the essentially anywhere in the world in 10 h. last 40 years has been fueled by advancements in a broad History range of aeronautical technologies,combined with strong economic growth.Continued advancements in aerodynamics,structures,ma- As shown in Fig.3,supersonic aircraft progress from the first su- terials,avionics,and engine technology have provided the techni- personic flight in 1947 has been impressive.In less than 15 years,the cal basis for the development of many different predominantly jet- B58 was setting records for flights at Mach 2 between New York and powered civil aircraft models.These aircraft range from the very London in less than 4 h.However,progress was almost completely large transports used by scheduled air carriers to the very small limited to military aircraft.In the 1960s,three projects were initiated personal jets emerging currently.Technical advancements coupled to bring supersonic civil transportation to market.The three differ- with economic growth have produced an exceptional record of avi- ent projects were nationally oriented.The U.S.supersonic transport ation market growth,as shown in Fig.1.This growth has included (SST)program was stopped before an aircraft was even built.The a significant expansion of the small civil aircraft market involving Russian Tu144 was first to flight but ultimately was removed from regional jets,business jets,and,now,personal jets. service.Only the British/French Concorde continued service until One of the market factors that has proven important in the growth 2003. of small civil aircraft market is the value of time in transportation Continuation of the Concorde service was largely related to na- needs.Air travel provides the highest travel speeds for trips of sig- tionalistic pride in the remarkable aeronautical achievement em- nificant distance.Scheduled carrier use of the regional jet satisfies bodied in the Concorde.Concorde economics and environmental the need to bring the time value of jet transport to low-density routes impacts limited its utility and represent a challenge in the contem- and markets.Business jet use by charter operators,fractional own- plation of future advancements in supersonic civil transportation. ers,public companies,private companies,and individuals is strongly The lesson of Concorde,as well as the other two less successful at- tied to the value of time.Business jet use and the emerging personal tempts,is that aeronautical prowess is a necessary but not sufficient jet use provide time value through jet aircraft speed and through condition for the creation of successful programs in supersonic civil broad destination flexibility.Exceptional field length performance aviation.Economic justification and environmental compatibility enables the small civil aircraft to operate into a remarkable number are also required.Subsequent to the original SST Program,the U.S.. of locations.Combine destination flexibility and jet aircraft speed in on at least two occasions-supersonic cruise research(SCAR)and a competitive business environment and one has a highly valuable high speed civil transport(HSCT)7-attempted to promote and de- means to satisfy transportation needs. velop a large supersonic civil transport,only to see the projects fail. In these later cases.the technical.environmental.and economic Attraction equations still could not be satisfied.Quite coincidentally,the an- Recognition of the ever-increasing value of time has lead to nouncement of Concorde service termination in 2003 coincides with increased interest in the feasibility of a small supersonic civil the first flight centennial celebration year. aircraft.-The step to supersonic speeds offers the potential of Whereas the stunning attraction of Fig.2 is clear to most air trav- a dramatic decrease in travel time.As shown in Fig.2,when speed elers,the supersonic stagnation reflected in Fig.3 demands a new is doubled from today's subsonic 0.8-0.85 Mach number to a 1.8 approach.The studies conducted in the last few yearsprovide Mach number,global transportation paradigms transforms.Leaving compelling evidence that the new approach should be focused on a New York City at 0700 hrs in a quiet supersonic jet(QSJ),one can much smaller vehicle as the first commercially and environmentally be anywhere in the indicated circle for at least 2 h and be back in successful step in supersonic civil aviation.The history of advances New York City by 1900 hrs.Alternatively,one could depart New in transportation has been more often defined by the introduction of a paradigm shift,first on a modest scale rather than a giant scale These advances in transportation technology were usually aimed at the more affluent as a means of introductory affordability.Once Presented as Paper 2003-2555 at the AlAA/ICAS International Air and the concept has been proven on a small scale for the more afflu- Space Symposium and Exposition:The Next 100 Years,Dayton,OH. ent,then technical advances and commercial competition have typ- 14-17 July 2003;received 10 September 2003;revision received 11 January ically led to larger-scale vehicles that appeal to a broader segment 2004;accepted for publication 14 January 2004.Copyright C 2004 by of the population.This small-to-large stepping stone approach has Preston A.Henne.Published by the American Institute of Aeronautics and clearly occurred throughout ship and aircraft transportation system Astronautics,Inc.,with permission.Copies of this paper may be made for personal or internal use,on condition that the copier pay the $10.00 per-copy history and reflects an intuitive risk management.In hindsight,it fee to the Copyright Clearance Center,Inc.,222 Rosewood Drive,Danvers. would seem that the aeronautical community has been trying to run MA 01923:include the code 0021-8669/05 $10.00 in correspondence with supersonically before it can walk supersonically.It has been try- the CCC. ing to create the giant supersonic transport before it developed the *Senior Vice-President,Programs,Engineering,and Test.Fellow AlAA supersonic DC-3.Supersonic long-term vision took priority over 765

JOURNAL OF AIRCRAFT Vol. 42, No. 3, May–June 2005 Case for Small Supersonic Civil Aircraft Preston A. Henne∗ Gulfstream Aerospace Corporation, Savannah, Georgia 31402 Civil aviation progress in the last 40 years has included a significant expansion of the small civil aircraft market involving regional jets, business jets, and the emerging personal jets. A significant factor in the growth of the small civil aircraft market is the value of time. Recognition of the ever-increasing value of time has lead to increased interest in the feasibility of a small supersonic civil aircraft. The step to supersonic speeds offers the potential of a dramatic decrease in travel time. Feasibility studies of a small quiet supersonic jet (QSJ) have been conducted. Market research, environmental concerns, program and design requirements, and vehicle characteristics are sum￾marized. Areas for concentrated future supersonic aeronautics research and development efforts are highlighted. Introduction T HE remarkable progress and growth in civil aviation in the last 40 years has been fueled by advancements in a broad range of aeronautical technologies, combined with strong economic growth. Continued advancements in aerodynamics, structures, ma￾terials, avionics, and engine technology have provided the techni￾cal basis for the development of many different predominantly jet￾powered civil aircraft models. These aircraft range from the very large transports used by scheduled air carriers to the very small personal jets emerging currently. Technical advancements coupled with economic growth have produced an exceptional record of avi￾ation market growth, as shown in Fig. 1. This growth has included a significant expansion of the small civil aircraft market involving regional jets, business jets, and, now, personal jets. One of the market factors that has proven important in the growth of small civil aircraft market is the value of time in transportation needs. Air travel provides the highest travel speeds for trips of sig￾nificant distance. Scheduled carrier use of the regional jet satisfies the need to bring the time value of jet transport to low-density routes and markets. Business jet use by charter operators, fractional own￾ers, public companies, private companies, and individuals is strongly tied to the value of time. Business jet use and the emerging personal jet use provide time value through jet aircraft speed and through broad destination flexibility. Exceptional field length performance enables the small civil aircraft to operate into a remarkable number of locations. Combine destination flexibility and jet aircraft speed in a competitive business environment and one has a highly valuable means to satisfy transportation needs. Attraction Recognition of the ever-increasing value of time has lead to increased interest in the feasibility of a small supersonic civil aircraft.1−5 The step to supersonic speeds offers the potential of a dramatic decrease in travel time. As shown in Fig. 2, when speed is doubled from today’s subsonic 0.8–0.85 Mach number to a 1.8 Mach number, global transportation paradigms transforms. Leaving New York City at 0700 hrs in a quiet supersonic jet (QSJ), one can be anywhere in the indicated circle for at least 2 h and be back in New York City by 1900 hrs. Alternatively, one could depart New Presented as Paper 2003-2555 at the AIAA/ICAS International Air and Space Symposium and Exposition: The Next 100 Years, Dayton, OH, 14–17 July 2003; received 10 September 2003; revision received 11 January 2004; accepted for publication 14 January 2004. Copyright c 2004 by Preston A. Henne. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Copies of this paper may be made for personal or internal use, on condition that the copier pay the $10.00 per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923; include the code 0021-8669/05 $10.00 in correspondence with the CCC. ∗Senior Vice-President, Programs, Engineering, and Test. Fellow AIAA. York City heading westbound or eastbound and, with one stop, be essentially anywhere in the world in 10 h. History As shown in Fig. 3, supersonic aircraft progress from the first su￾personic flight in 1947 has been impressive. In less than 15 years, the B58 was setting records for flights at Mach 2 between New York and London in less than 4 h. However, progress was almost completely limited to military aircraft. In the 1960s, three projects were initiated to bring supersonic civil transportation to market. The three differ￾ent projects were nationally oriented. The U.S. supersonic transport (SST) program was stopped before an aircraft was even built. The Russian Tu144 was first to flight but ultimately was removed from service. Only the British/French Concorde continued service until 2003. Continuation of the Concorde service was largely related to na￾tionalistic pride in the remarkable aeronautical achievement em￾bodied in the Concorde. Concorde economics and environmental impacts limited its utility and represent a challenge in the contem￾plation of future advancements in supersonic civil transportation. The lesson of Concorde, as well as the other two less successful at￾tempts, is that aeronautical prowess is a necessary but not sufficient condition for the creation of successful programs in supersonic civil aviation. Economic justification and environmental compatibility are also required. Subsequent to the original SST Program, the U.S., on at least two occasions—supersonic cruise research (SCAR)6 and high speed civil transport (HSCT)7—attempted to promote and de￾velop a large supersonic civil transport, only to see the projects fail. In these later cases, the technical, environmental, and economic equations still could not be satisfied. Quite coincidentally, the an￾nouncement of Concorde service termination in 2003 coincides with the first flight centennial celebration year. Whereas the stunning attraction of Fig. 2 is clear to most air trav￾elers, the supersonic stagnation reflected in Fig. 3 demands a new approach. The studies conducted in the last few years1,2,8 provide compelling evidence that the new approach should be focused on a much smaller vehicle as the first commercially and environmentally successful step in supersonic civil aviation. The history of advances in transportation has been more often defined by the introduction of a paradigm shift, first on a modest scale rather than a giant scale. These advances in transportation technology were usually aimed at the more affluent as a means of introductory affordability. Once the concept has been proven on a small scale for the more afflu￾ent, then technical advances and commercial competition have typ￾ically led to larger-scale vehicles that appeal to a broader segment of the population. This small-to-large stepping stone approach has clearly occurred throughout ship and aircraft transportation system history and reflects an intuitive risk management. In hindsight, it would seem that the aeronautical community has been trying to run supersonically before it can walk supersonically. It has been try￾ing to create the giant supersonic transport before it developed the supersonic DC-3. Supersonic long-term vision took priority over 765

766 HENNE 1000 Actual Forecast Recessionary Periods 气 Commercial Jets Business Jets 400 200 Regional Jets 92 1982 1951988 1991 1994 1997 20002003 200e Year Fig.1 Aviation market growth measured in units delivered per year. Speed that redefines a 12 hour work day --there and back with 2 hours minimum on location Assuming Mach 1.8, 4,500 nm range Hono capability Westbound from New York Eastbound from New York Worldwide Coverage in 10 hours Fig.2 Doubling speed brings remarkable transportation value. 3.5 Military O Commercial XB70 3.0 B2707U.S. 104 Never Built 2.5 Tu144 Russia Ops Stopped 爱 Fr/UK 0558 JaqwnN yoeW 2.0 "In Service" F100 No B58 Ops Stopped 2003 Supersonic 30 Years with No New Civil Supersonic Civil Transport Transport 1.0 45 Years of Subsonic Civil Jet Transports 0.5 0.0 1940 1950 1960 1970 1980 1990 2000 2010 2020 Year Fig.3 Supersonic aircraft progress

766 HENNE Fig. 1 Aviation market growth measured in units delivered per year. Fig. 2 Doubling speed brings remarkable transportation value. Fig. 3 Supersonic aircraft progress

HENNE 767 supersonic foundations.An effective supersonic vehicle needs to well as business aviation use.These studies have concluded that be introduced on a small scale first.The technical,economic.and a small supersonic civil aircraft market of 250-450 units exists at environmental equations need to be solved on a lower-risk,small a price between $50M and S100M per unit over a 10-20 year pe- scale before the giant,supersonic transport solution is once again riod.Additionally,a major fractional ownership company has con- attempted. ducted sufficient studies to conclude that a small supersonic civil aircraft has considerable appeal and seeks to participate in any such QS,J Market Research endeavor. At least four different market research studies have been con- The current perspective indicates there is a significant market ducted on the small QSJ in recent years.Gulfstream internal market potential for a small supersonic civil aircraft.Market assessments research has consisted of both a bottom-up approach and an analyt- have identified the following significant points: ical projection based on historical regression analysis.Independent 1)Two Gulfstream market assessments identify conservative market research studies utilizing direct customer contact and ques sales forecasts of 180-350 aircraft. tionnaires have also been reported.3> 2)Two independent market assessments identify sales forecasts The bottom-up approach was based on an assessment of the large- of 250-450 aircraft. cabin business aircraft known customer base.This approach essen- 3)Supersonic overland flight capability is a requirement. tially amounted to a count of the individual customers who would 4)Range beyond 4000 n mile is a requirement. step up to the next level of transportation productivity if it was avail- The supersonic overland flight requirement is key to the market able.The results of this study indicated a minimum market potential feasibility.Sonic boom suppression is the key technology required of 180 unitsover 10years.This result did not include special mission to make supersonic overland flight acceptable.All of the market or government sales and did not account for fractional ownership studies have confirmed significant value for this capability.A limi- needs.The 180 unit number is a good threshold volume.A model tation to subsonic overland flight,as a result of unacceptable sonic run of 200 units is typical for programs throughout the 40-plus year boom characteristics,represents a severe blow to the value of a small history of Gulfstream Aerospace Corporation. supersonic civil aircraft.Production costs,both nonrecurring and re- The analytical projection method extrapolated historic annual de- curring,for the supersonic vehicle are present whether or not the livery data for large cabin business jet deliveries and inferred the vehicle is limited to subsonic overland flight.The market price or potential for a QSJ product serving the same customer group.The value that the vehicle can command is strongly driven by its ability historic annual delivery data were approximated by determination of to maximize time savings.As shown in Fig.5,much of small civil a best-fit constant growth rate.This growth rate applied year-after- aircraft flight is over land.In this case,a random sample of flights year yields a fleet size equivalent to the actual historic data.Once was taken from actual flight records for the in-service Gulfstream determined,this growth rate was used to extrapolate anticipated GIV and Gulfstream GV aircraft for one year.The sample indicates future deliveries.Historically,a conservative 10%capture is recog- that only 25%of the flight time was over water.Consequently,max- nized for new-capability product introductions.This future delivery imum time savings and maximum market value dictate supersonic estimate,coupled with the 10%market capture,provides a means overland flight requirements.If this higher market price(supersonic to estimate QSJ potential.The historic data,equivalent growth line overland capability)is not achieved,the business case is weak,and and projected QSJ deliveries are illustrated in Fig.4.It is interest- we have not solved the economic equation.The supersonic-over- ing that this long-term regression analysis discounts the blistering water-only assumption made in previous large supersonic transport delivery levels of the late 1990s/early 2000s.As has been noted re- studies certainly hindered,if not fatally restricted,the aircraft po- cently,delivery levels have retreated back to levels actually closer to tential in the marketplace.Consequently,definition of an acceptable the projection line.This projection method results in a QSJ market solution for sonic boom suppression is key to the success of a small potential over a 10-year period to be over 350 units.Independent supersonic civil aircraft. market research studies have also been conducted.3-5 These studies have used extensive customer surveys and considered a number of Environmental Concerns questions to clarify product requirements.They have also introduced The viability of a supersonic civil aircraft hinges on the ability the concept of a small supersonic aircraft for scheduled service,as to design and manufacture a configuration that is environmentally 1000 Projection Assuming a 6.2%AAGR seleAllea er sseulsng History 2.277 Units Over 36 Years 100 QSJ Projection 190 to 570 Units (2013-2022) 10 1960 1970 1980 1990 2000 2010 2020 2030 Year Projected QSJ Market Equal to 350+ Airplanes over 10 Year Period Fig.4 Analytical projection approach for QSJ market forecast

HENNE 767 supersonic foundations. An effective supersonic vehicle needs to be introduced on a small scale first. The technical, economic, and environmental equations need to be solved on a lower-risk, small scale before the giant, supersonic transport solution is once again attempted. QSJ Market Research At least four different market research studies have been con￾ducted on the small QSJ in recent years. Gulfstream internal market research has consisted of both a bottom-up approach and an analyt￾ical projection based on historical regression analysis. Independent market research studies utilizing direct customer contact and ques￾tionnaires have also been reported.3−5 The bottom-up approach was based on an assessment of the large￾cabin business aircraft known customer base. This approach essen￾tially amounted to a count of the individual customers who would step up to the next level of transportation productivity if it was avail￾able. The results of this study indicated a minimum market potential of 180 units over 10 years. This result did not include special mission or government sales and did not account for fractional ownership needs. The 180 unit number is a good threshold volume. A model run of 200 units is typical for programs throughout the 40-plus year history of Gulfstream Aerospace Corporation. The analytical projection method extrapolated historic annual de￾livery data for large cabin business jet deliveries and inferred the potential for a QSJ product serving the same customer group. The historic annual delivery data were approximated by determination of a best-fit constant growth rate. This growth rate applied year-after￾year yields a fleet size equivalent to the actual historic data. Once determined, this growth rate was used to extrapolate anticipated future deliveries. Historically, a conservative 10% capture is recog￾nized for new-capability product introductions. This future delivery estimate, coupled with the 10% market capture, provides a means to estimate QSJ potential. The historic data, equivalent growth line, and projected QSJ deliveries are illustrated in Fig. 4. It is interest￾ing that this long-term regression analysis discounts the blistering delivery levels of the late 1990s/early 2000s. As has been noted re￾cently, delivery levels have retreated back to levels actually closer to the projection line. This projection method results in a QSJ market potential over a 10-year period to be over 350 units. Independent market research studies have also been conducted.3−5 These studies have used extensive customer surveys and considered a number of questions to clarify product requirements. They have also introduced the concept of a small supersonic aircraft for scheduled service, as Fig. 4 Analytical projection approach for QSJ market forecast. well as business aviation use. These studies have concluded that a small supersonic civil aircraft market of 250–450 units exists at a price between $50M and $100M per unit over a 10–20 year pe￾riod. Additionally, a major fractional ownership company has con￾ducted sufficient studies to conclude that a small supersonic civil aircraft has considerable appeal and seeks to participate in any such endeavor. The current perspective indicates there is a significant market potential for a small supersonic civil aircraft. Market assessments have identified the following significant points: 1) Two Gulfstream market assessments identify conservative sales forecasts of 180–350 aircraft. 2) Two independent market assessments identify sales forecasts of 250–450 aircraft. 3) Supersonic overland flight capability is a requirement. 4) Range beyond 4000 n mile is a requirement.1 The supersonic overland flight requirement is key to the market feasibility. Sonic boom suppression is the key technology required to make supersonic overland flight acceptable. All of the market studies have confirmed significant value for this capability. A limi￾tation to subsonic overland flight, as a result of unacceptable sonic boom characteristics, represents a severe blow to the value of a small supersonic civil aircraft. Production costs, both nonrecurring and re￾curring, for the supersonic vehicle are present whether or not the vehicle is limited to subsonic overland flight. The market price or value that the vehicle can command is strongly driven by its ability to maximize time savings. As shown in Fig. 5, much of small civil aircraft flight is over land. In this case, a random sample of flights was taken from actual flight records for the in-service Gulfstream GIV and Gulfstream GV aircraft for one year. The sample indicates that only 25% of the flight time was over water. Consequently, max￾imum time savings and maximum market value dictate supersonic overland flight requirements. If this higher market price (supersonic overland capability) is not achieved, the business case is weak, and we have not solved the economic equation. The supersonic-over￾water-only assumption made in previous large supersonic transport studies certainly hindered, if not fatally restricted, the aircraft po￾tential in the marketplace. Consequently, definition of an acceptable solution for sonic boom suppression is key to the success of a small supersonic civil aircraft. Environmental Concerns The viability of a supersonic civil aircraft hinges on the ability to design and manufacture a configuration that is environmentally

768 HENNE 3500 目Over Water 3000 Over Land 2500 2000 1500 1000 500 Average range:1290 n.m. Percent of miles flown over water:25% Fig.5 Random sample of small civil aircraft operation compatible.6 In this context,environmentally compatible means effectively addressing the following:1)sonic boom,2)engine ex- Initial Cruise Sonic Boom Strength haust emissions,and 3)airport noise.A feasible design must reduce 3.0 the configuration's sonic boom signature such that supersonic flight HSCT over land is acceptable to the public.As discussed earlier,the market 2.5 research studies have repeatedly confirmed that supersonic overland Concorde flight is of critical importance to the value of the vehicle..3.5 The 2.0 design must also minimize adverse atmospheric effects due to en- gine exhaust emissions throughout all operations.Emissions must SBJ be minimized during both low-speed,low-altitude airport operations 1.5 as well as high-altitude supersonic cruise operations.Furthermore, a successful QSJ must be a quiet,good neighbor to the airport en- 1.0 vironment.It should make no more noise than today's quiet small QSJ Shaped DARPA QSP Goal subsonic civil jets. QSJ Internal Concepts Sonic Boom The effort to suppress sonic boom successfully has several ma- 200000 400000 600000 800000 jor aspects.First,the vehicle aerodynamic design is used to shape Initial Cruise Weight-lb the sonic boom signature.Shaped signatures are defined by the prevention of coalescence of the signature into an annoying N- Fig.6 Sonic boom initial overpressure strongly affected by vehicle shaped pressure wave.Second,psychoacoustic testing is being used weight. to establish signature levels and desired signature shapes that are considered environmentally acceptable.Third,a flight demonstra- Gulfstream has defined several unique airplane configuration tion will be required to prove boom suppression acceptability.A details that reduce the initial overpressure and enhance the vehi- flight demonstration will provide a foundation of scientific data cle designer's ability to control the shape of the ground signature necessary for regulation of supersonic overland flight,as well as produced.Results for several of these configurations are in- risk reduction for the business decision to launch a production dicated in Figs.6 and 7.Several of these design concepts have program. been validated in recent wind-tunnel testing conducted at NASA When the physics of sonic boom are considered,it is very clear Langley's 4 Foot Unitary Wind Tunnel.As indicated in Fig.8 that a small aircraft has a profound advantage over large aircraft.The the data for the advanced boom suppression concepts show very size and weight of a vehicle has a first-order effect on the strength of promising signature characteristics.Based on these computational the sonic boom signature.As the vehicle weight decreases,the sonic fluid dynamics(CFD)and wind-tunnel test results,initial overpres- boom disturbance is decreased.Careful attention to the physical sures of less than 0.2 psf and peak overpressures of 0.5-0.6 psf shape of the vehicle can result in a shaped ground signature rather seem quite achievable.Clearly,additional model and flight test- than a coalesced N wave.Shaped ground signatures avoid the large ing are needed to develop,validate,and fully exploit sonic boom abrupt pressure increases associated with beginning and end of a suppression technology.This aerodynamic technology need is a typical sonic boom N wave.Shaped signatures have lower initial long-standing aeronautical barrier that has not yet been adequately and final pressure increases and are perceived as substantially quieter addressed. due to their more-sinusoidal,very-low-frequency character.Shaped Sonic boom strength for configurations with signatures such as signatures can be thought of as precoalesced signatures designed to those in Figs.7 and 8 have been analyzed in terms of perceived a special wave shape. level of noise in decibels (PLdB)and A-weighted noise in decibels Figures 6 and 7 show the impact of vehicle size and shaping [dB(A)].The results shown in Fig.9 show a remarkable improve- on the sonic boom ground signature.These charts show data for a ment in the cruise signature acoustic strength.Results for configu- 300-passenger high-speed civil transport(HSCT),the Concorde,a rations shown in Fig.9 indicate that the noise levels can be reduced generic supersonic business jet(SBJ),and two QS]configurations. more than 35 dB below that of the Concorde sonic boom.These The effect of weight alone is shown in Fig.6 by the line connecting levels are at or below conversation-level acoustics.Such signatures three N-wave vehicles:HSCT,Concorde,and SBJ. are better characterized as sonic puffs rather than as sonic booms

768 HENNE Fig. 5 Random sample of small civil aircraft operation. compatible.1,6 In this context, environmentally compatible means effectively addressing the following: 1) sonic boom, 2) engine ex￾haust emissions, and 3) airport noise. A feasible design must reduce the configuration’s sonic boom signature such that supersonic flight over land is acceptable to the public. As discussed earlier, the market research studies have repeatedly confirmed that supersonic overland flight is of critical importance to the value of the vehicle.1,3,5 The design must also minimize adverse atmospheric effects due to en￾gine exhaust emissions throughout all operations. Emissions must be minimized during both low-speed, low-altitude airport operations as well as high-altitude supersonic cruise operations. Furthermore, a successful QSJ must be a quiet, good neighbor to the airport en￾vironment. It should make no more noise than today’s quiet small subsonic civil jets. Sonic Boom The effort to suppress sonic boom successfully has several ma￾jor aspects. First, the vehicle aerodynamic design is used to shape the sonic boom signature. Shaped signatures are defined by the prevention of coalescence of the signature into an annoying N￾shaped pressure wave. Second, psychoacoustic testing is being used to establish signature levels and desired signature shapes that are considered environmentally acceptable. Third, a flight demonstra￾tion will be required to prove boom suppression acceptability. A flight demonstration will provide a foundation of scientific data necessary for regulation of supersonic overland flight, as well as risk reduction for the business decision to launch a production program. When the physics of sonic boom are considered,9 it is very clear that a small aircraft has a profound advantage over large aircraft. The size and weight of a vehicle has a first-order effect on the strength of the sonic boom signature. As the vehicle weight decreases, the sonic boom disturbance is decreased. Careful attention to the physical shape of the vehicle can result in a shaped ground signature rather than a coalesced N wave. Shaped ground signatures avoid the large abrupt pressure increases associated with beginning and end of a typical sonic boom N wave. Shaped signatures have lower initial and final pressure increases and are perceived as substantially quieter due to their more-sinusoidal, very-low-frequency character. Shaped signatures can be thought of as precoalesced signatures designed to a special wave shape. Figures 6 and 7 show the impact of vehicle size and shaping on the sonic boom ground signature. These charts show data for a 300-passenger high-speed civil transport (HSCT), the Concorde, a generic supersonic business jet (SBJ), and two QSJ configurations. The effect of weight alone is shown in Fig. 6 by the line connecting three N-wave vehicles: HSCT, Concorde, and SBJ. Fig. 6 Sonic boom initial overpressure strongly affected by vehicle weight. Gulfstream has defined several unique airplane configuration details that reduce the initial overpressure and enhance the vehi￾cle designer’s ability to control the shape of the ground signature produced.10,11 Results for several of these configurations are in￾dicated in Figs. 6 and 7. Several of these design concepts have been validated in recent wind-tunnel testing conducted at NASA Langley’s 4 Foot Unitary Wind Tunnel. As indicated in Fig. 8, the data for the advanced boom suppression concepts show very promising signature characteristics. Based on these computational fluid dynamics (CFD) and wind-tunnel test results, initial overpres￾sures of less than 0.2 psf and peak overpressures of 0.5–0.6 psf seem quite achievable. Clearly, additional model and flight test￾ing are needed to develop, validate, and fully exploit sonic boom suppression technology. This aerodynamic technology need is a long-standing aeronautical barrier that has not yet been adequately addressed. Sonic boom strength for configurations with signatures such as those in Figs. 7 and 8 have been analyzed in terms of perceived level of noise in decibels (PLdB) and A-weighted noise in decibels [dB(A)]. The results shown in Fig. 9 show a remarkable improve￾ment in the cruise signature acoustic strength. Results for configu￾rations shown in Fig. 9 indicate that the noise levels can be reduced more than 35 dB below that of the Concorde sonic boom. These levels are at or below conversation-level acoustics. Such signatures are better characterized as sonic puffs rather than as sonic booms

HENNE 769 3.0 ●HSCT/2.4W57KW190 2.5 -Concorde/2.0M/49K/243 ☐-SBJ/1.8W55K/333 01510 ■QSJ/1.8W55K/333 ●-QSJ++H1.8W55KW333 1.0 -1.5 -2.0 -2.5 50 0 50 100 150200 250300 350 400 Time(msec) Fig.7 Ground boom signature progression with vehicle size reduction and advanced shaping concepts DARPA Initial Wind Tunnel Test Data-Symbols Overpressure Goal CFD Calculation-Lines 。 0.4 1.8M 0.2 耍 0.0 0.2 Low Boom Config 1 -0.4 Low Boom Config 2 -0.6 Excellent Correlation&Validation of Boom Suppression Concepts -0.8 0.0 X/Body Length 1.0 2.0 Gulfstream Wind Tunnel Models in NASA Langley UPWT Fig.8 Advanced boom suppression concept testing results QSJ Advanced+>35dB Quieter Than Concorde Engine Exhaust Emissions Engine exhaust emissions are another environmental concern that 口PLdB must be addressed responsibly.In the airport environment there are ■dB(A) regulations that can be used as design goals.These regulations limit oxides of nitrogen(NOx),unburned hydrocarbons,carbon monox- >35dB Reduction ide,and smoke emissions.These existing limits are well under- dB(A) stood and currently considered well within the QSJ design capa- bility.Unfortunately,this clearly defined situation is not the case Traffic for engine emissions at high-altitude cruise conditions.There are no current regulations or standards for cruise emissions.This ab- Talking sence of current regulations,however,does not mean the issue can be neglected.In fact,a lack of understanding about cruise emis- sions has been a key argument against previous supersonic transport programs.6 The difficulty in early programs was lack of credible un- SCT derstanding of atmospheric science.The absence of such knowledge Configuration left the door open for wild and exaggerated claims of atmospheric trauma based on speculation,misinformation,and political agen- Fig.9 Progress in lowering sonic boom strength. das.The current state of knowledge has advanced sufficiently to

HENNE 769 Fig. 7 Ground boom signature progression with vehicle size reduction and advanced shaping concepts. Fig. 8 Advanced boom suppression concept testing results. Fig. 9 Progress in lowering sonic boom strength. Engine Exhaust Emissions Engine exhaust emissions are another environmental concern that must be addressed responsibly. In the airport environment there are regulations that can be used as design goals. These regulations limit oxides of nitrogen (NOx), unburned hydrocarbons, carbon monox￾ide, and smoke emissions. These existing limits are well under￾stood and currently considered well within the QSJ design capa￾bility. Unfortunately, this clearly defined situation is not the case for engine emissions at high-altitude cruise conditions. There are no current regulations or standards for cruise emissions. This ab￾sence of current regulations, however, does not mean the issue can be neglected. In fact, a lack of understanding about cruise emis￾sions has been a key argument against previous supersonic transport programs.6 The difficulty in early programs was lack of credible un￾derstanding of atmospheric science. The absence of such knowledge left the door open for wild and exaggerated claims of atmospheric trauma based on speculation, misinformation, and political agen￾das. The current state of knowledge has advanced sufficiently to

770 HENNE make credible estimates of atmospheric impacts of aircraft cruise through proper aircraft design requirements.If QSJ cruise altitudes emissions.12 can be held down close to the 47,000-ft.crossover point,then the An analytical atmospheric model study has been conducted as ozone impact will be less than a few hundredths of a percent.This a first proactive step toward understanding a QSJ fleet impact on effect is several orders of magnitude less than was feared for an the atmosphere.One important aspect of the study is an under- HSCT fleet and is likely imperceptible.It is also achieved with far standing of the impact of engine NOx emissions on atmospheric less exotic combustor requirements,as indicated by the EI(NOx) ozone.Figure 10 presents some of the results of this study rela- values of 15.20. tive to ozone impact.2 The estimated annually averaged change in In addition to NOx,emissions of H2O and CO2 need to be Northern Hemisphere total column ozone (in percent)due to the minimized.This minimization is easily translated into a minimiza- operation of a QSJ fleet is shown.Similar atmospheric impact data tion of aircraft weight and engine specific fuel consumption(SFC) have been estimated for the current commercial subsonic transport concurrent with a maximization of aerodynamic lift-to-drag ratio fleet and a large supersonic transport(HSCT)fleet.These estimates (L/D).Of course,this menu is nothing more than the pursuit of fun- are presented in Fig.10 for comparison. damental aeronautical efficiencies."Green Aircraft"solutions are The results of this atmospheric model work indicate that the en- still driven by aeronautical fundamentals.An aggressive,balanced visioned QSJ fleet impact on the Earth's ozone is essentially neutral program of continuous aeronautical research and development in when compared to either the subsonic fleet or an HSCT fleet.An L/D,SFC,structures,and materials technology is sorely needed to important conclusion of the study is that the much smaller size of advance the low-emissions aeronautical state of the art. the QSJ,compared to the HSCT,combined with the slightly slower speed(1.8 vs 2.4 Mach number)yields a very favorable impact as- Airport Noise sessment.The slower speed is a primary factor in lowering cruise Operational flexibility requirements dictate that the QSJ must be altitudes to near the crossover point,where the NOx impact on total designed to exceed the regulatory requirements for airport noise. column ozone changes sign (see Fig.11).This atmospheric sci- Current regulations require aircraft to meet stage 3 noise limits. ence understanding can now be exploited to minimize ozone impact After 2006,all new aircraft will be required to meet stage 4.a 0.75 QSJ-Essentially 0.50 Ozone Neutral 0.25 % 0.25 HsCT,EI(NOx)=10 0.50 ▣HSCT,EINOx)■15 0.75 口Subsonic only 口QSJ,49.5k-54.1k,E0w0x=15 1.00 ▣Q5J,4g.5k-54.1k,EN0x0=20 125 QSJ,54.1k-59k,EI(NOx)=15 Aircraft Types QSJ,54.1k-59k,EI(NOx)=20 -1.50 Fleet Size E.I.(NOx)Est Ann.FIt Hrs Altitude High Speed Civil Trans. 500 10,15 1000-3000 56k-66k Commercial Subsonic 50.000+ 3000+ 32k-43k QSJ 400 15,20 1000 49k-54k QSJ 400 15,20 1000 54k-59k Fig.10 Atmospheric modeling studies indicate minimal QS.J impact on ozone. EI(NOx)=20 Emissions Below 47k ft Increase 0.02 Ozone Concentration uwnlo 0.00 -0.02 0.04 IeoL HN -0.06 -0.08 -0.10 QSJ Design Strategy- -0.12 Keep Cruise Altitude in -0.14 ◆Fuel Burn:=3MIbs/day This Range-Nearly -0.16 -Fuel Burn=10 MIbs/day Ozone Neutral 0.18 Fuel Burn=18 MIbs/day 0.20 35 50 55 % 65 Approximate Cruise Altitude(k ft) Ozone Impact of QSJ Fleet Operations Negligible Fig.11 NOx emission ozone impact crossover point and sensitivities

770 HENNE make credible estimates of atmospheric impacts of aircraft cruise emissions.12 An analytical atmospheric model study has been conducted as a first proactive step toward understanding a QSJ fleet impact on the atmosphere. One important aspect of the study is an under￾standing of the impact of engine NOx emissions on atmospheric ozone. Figure 10 presents some of the results of this study rela￾tive to ozone impact.12 The estimated annually averaged change in Northern Hemisphere total column ozone (in percent) due to the operation of a QSJ fleet is shown. Similar atmospheric impact data have been estimated for the current commercial subsonic transport fleet and a large supersonic transport (HSCT) fleet. These estimates are presented in Fig. 10 for comparison. The results of this atmospheric model work indicate that the en￾visioned QSJ fleet impact on the Earth’s ozone is essentially neutral when compared to either the subsonic fleet or an HSCT fleet. An important conclusion of the study is that the much smaller size of the QSJ, compared to the HSCT, combined with the slightly slower speed (1.8 vs 2.4 Mach number) yields a very favorable impact as￾sessment. The slower speed is a primary factor in lowering cruise altitudes to near the crossover point, where the NOx impact on total column ozone changes sign (see Fig. 11). This atmospheric sci￾ence understanding can now be exploited to minimize ozone impact Fig. 10 Atmospheric modeling studies indicate minimal QSJ impact on ozone. Fig. 11 NOx emission ozone impact crossover point and sensitivities. through proper aircraft design requirements. If QSJ cruise altitudes can be held down close to the 47,000-ft. crossover point, then the ozone impact will be less than a few hundredths of a percent. This effect is several orders of magnitude less than was feared for an HSCT fleet and is likely imperceptible. It is also achieved with far less exotic combustor requirements, as indicated by the EI(NOx) values of 15,20. In addition to NOx, emissions of H2O and CO2 need to be minimized. This minimization is easily translated into a minimiza￾tion of aircraft weight and engine specific fuel consumption (SFC) concurrent with a maximization of aerodynamic lift-to-drag ratio (L/D). Of course, this menu is nothing more than the pursuit of fun￾damental aeronautical efficiencies. “Green Aircraft” solutions are still driven by aeronautical fundamentals. An aggressive, balanced program of continuous aeronautical research and development in L/D, SFC, structures, and materials technology is sorely needed to advance the low-emissions aeronautical state of the art. Airport Noise Operational flexibility requirements dictate that the QSJ must be designed to exceed the regulatory requirements for airport noise. Current regulations require aircraft to meet stage 3 noise limits. After 2006, all new aircraft will be required to meet stage 4, a

HENNE 771 0 Increasing Technical Challenge 5 10.0d8-8.7dB Aerodynamic Heating Chapter 4 and Stage Flyover 4 Limit Margin Inlet Complexity Sonic Boom GIV-SP GV Aero Center shitt Margin 7Rproa8 4. Supersonic Acceleration -20 Margin -21.1 21.9 Transonic Drag Rise -25 QSJ QSJ Requirement Todav's Target Standard Future Designs Should Not Be Any Noisier .0 0.5 1.0 1.5 2.0 Than Todayis Product Standard Cruise Mach Number(Time Savings) Fig.14 Supersonic speed challenges. Fig.12 QSJ community noise requirements. Sideline Fly Over Approach pability.Clearly,supersonic overland flight is the highest risk item for small supersonic civil aircraft feasibility.Current U.S.regula- tions,adopted in a time of significant international political agendas simply prohibit supersonic flight overland.This politically induced Margin to -10 prohibition,implemented decades ago,was a simple,quick regu- Stage 3 Noise latory response to fears of environmental catastrophes perceived Limit(dB) -15 to be associated with SSTs such as Concorde.The need exists to supersede this prohibition with a rational rule that protects the en- 20 Stage 4 Cumulative-10dB vironment while it allows the ability to advance with higher speed. Cumulative As discussed earlier,progress is being made to address sonic -25 boom suppression technology.This progress should culminate in a ▣GIV-SP■GV□QSJ flight demonstrator program.Such a program can provide at least three benefits: Initial Estimates Indicate 1)It provides technical substantiation of boom suppression Stage 4-10dB Is Achievable technology. Fig.13 Estimated QSJ certification noise levels. 2)It provides regulatory authorities with a means to specify con- fidently a rational and accepatable sonic boom rule. 3)It provides a significant risk reduction for the business decision 10-dB-quieter cumulative level of acoustic performance relative to stage 3.Current Gulfstream production airplanes,the Gulfstream on the launch of a small supersonic civil aircraft production program. 300/400(GIV-SP)and the Gulfstream 500/550(GV),are already Consequently,it is believed that a fundamental QSJ program re- quirement is a flight demonstrator program before a production pro- better than 10 dB quieter than stage 4.This community friendly gram commitment. sound level is illustrated in Fig.12.A viable QSJ configuration en- A second program risk area is associated with an increase in tering service after 2006 will have to at least meet stage 4 limits from technical complexity with increasing Mach number in the super- a regulatory standpoint.However,to ensure operational flexibility sonic regime.As indicated in Fig.14.technical challenges abound and product viability,the configuration must not be any noisier than in the jump to supersonic.However,it must be said that these are today's quiet small civil jets such as the GIV-SP and GV.This noise requirement translates into nominally stage 4 minus 10 dB cumula- not new and have been addressed in some fashion by the histori- cal achievements shown in Fig.3.When these challenges are put tive or stage 3 minus 20 dB cumulative,as indicated in Fig.12. into a civil vehicle context and commercial business case,it is easy To achieve this level of acoustic performance propulsion system, to draw a limit at Mach 2.0.Such a limit allows the program to design,integration,and airplane performance have to be merged ef- avoid risk associated with aerodynamic heating at higher speeds.It fectively.All three areas are being considered in QSJ configuration studies.By recognization of this noise requirement in QSJ config- also allows for reduced propulsion installation complexity and re- duced temperature effects in the propulsion system.Slightly lower uration studies,the vehicle configuration concepts have moved in Mach numbers are favored to reduce the cruise altitude for consid- a direction to ensure low community noise is attained.Initial es- erations such as ozone impact.Slightly higher cruise Mach num- timates for a baseline QSJ configuration acoustic performance are presented in Fig.13.The estimate indicates that the stage 4 minus bers are favored to maximize range through ML/D.Current Gulf- stream QSJ program studies are focused on cruise Mach numbers 10-dB requirement seems achievable. between 1.6 and 2.0.The current Gulfstream QSJ program baseline is1.8. Program and Design Requirements A third program risk area is associated with the combination of Program Requirements cabin cross section,vehicle gross weight,and range in excess of Program requirements for the QSJ are defined so that the tech- 4000 n mile.This is an interesting combination of characteristics. nical.environmental,and economic equations can be solved with Operational flexibility for small civil aircraft dictates a maximum manageable risk for an identified market.These requirements can takeoff gross weight of 100,000 lb or less.This constraint comes be summarized as follows: about for a number of reasons.Foremost of these is a broad number 1)Market potential must be significant. of important airports with gross weight limitations set at 100,000 lb. 2)Customer requirements for identified market must be satisfied. The need for light weight for suppressed sonic boom also drives to 3)Technical,environmental,and economic risks must be accept- gross weights of 100,000 lb or less.Unfortunately.detailed configu- able. ration design studies currently show that,for a vehicle at 100,000 lb Market research efforts discussed earlier indicate that a market the maximum allowable cabin size is not compatible with the large exists if a vehicle can be defined with supersonic overland flight ca- cabin business jet standup style cabin.This result is shown in Fig.15

HENNE 771 Fig. 12 QSJ community noise requirements. Fig. 13 Estimated QSJ certification noise levels. 10-dB-quieter cumulative level of acoustic performance relative to stage 3. Current Gulfstream production airplanes, the Gulfstream 300/400 (GIV-SP) and the Gulfstream 500/550 (GV), are already better than 10 dB quieter than stage 4. This community friendly sound level is illustrated in Fig. 12. A viable QSJ configuration en￾tering service after 2006 will have to at least meet stage 4 limits from a regulatory standpoint. However, to ensure operational flexibility and product viability, the configuration must not be any noisier than today’s quiet small civil jets such as the GIV-SP and GV. This noise requirement translates into nominally stage 4 minus 10 dB cumula￾tive or stage 3 minus 20 dB cumulative, as indicated in Fig. 12. To achieve this level of acoustic performance propulsion system, design, integration, and airplane performance have to be merged ef￾fectively. All three areas are being considered in QSJ configuration studies. By recognization of this noise requirement in QSJ config￾uration studies, the vehicle configuration concepts have moved in a direction to ensure low community noise is attained. Initial es￾timates for a baseline QSJ configuration acoustic performance are presented in Fig. 13. The estimate indicates that the stage 4 minus 10-dB requirement seems achievable. Program and Design Requirements Program Requirements Program requirements for the QSJ are defined so that the tech￾nical, environmental, and economic equations can be solved with manageable risk for an identified market. These requirements can be summarized as follows: 1) Market potential must be significant. 2) Customer requirements for identified market must be satisfied. 3) Technical, environmental, and economic risks must be accept￾able. Market research efforts discussed earlier indicate that a market exists if a vehicle can be defined with supersonic overland flight ca￾Fig. 14 Supersonic speed challenges. pability. Clearly, supersonic overland flight is the highest risk item for small supersonic civil aircraft feasibility. Current U.S. regula￾tions, adopted in a time of significant international political agendas, simply prohibit supersonic flight overland. This politically induced prohibition, implemented decades ago, was a simple, quick regu￾latory response to fears of environmental catastrophes perceived to be associated with SSTs such as Concorde. The need exists to supersede this prohibition with a rational rule that protects the en￾vironment while it allows the ability to advance with higher speed. As discussed earlier, progress is being made to address sonic boom suppression technology. This progress should culminate in a flight demonstrator program. Such a program can provide at least three benefits: 1) It provides technical substantiation of boom suppression technology. 2) It provides regulatory authorities with a means to specify con- fidently a rational and accepatable sonic boom rule. 3) It provides a significant risk reduction for the business decision on the launch of a small supersonic civil aircraft production program. Consequently, it is believed that a fundamental QSJ program re￾quirement is a flight demonstrator program before a production pro￾gram commitment. A second program risk area is associated with an increase in technical complexity with increasing Mach number in the super￾sonic regime. As indicated in Fig. 14, technical challenges abound in the jump to supersonic. However, it must be said that these are not new and have been addressed in some fashion by the histori￾cal achievements shown in Fig. 3. When these challenges are put into a civil vehicle context and commercial business case, it is easy to draw a limit at Mach 2.0. Such a limit allows the program to avoid risk associated with aerodynamic heating at higher speeds. It also allows for reduced propulsion installation complexity and re￾duced temperature effects in the propulsion system. Slightly lower Mach numbers are favored to reduce the cruise altitude for consid￾erations such as ozone impact. Slightly higher cruise Mach num￾bers are favored to maximize range through ML/D. Current Gulf￾stream QSJ program studies are focused on cruise Mach numbers between 1.6 and 2.0. The current Gulfstream QSJ program baseline is 1.8. A third program risk area is associated with the combination of cabin cross section, vehicle gross weight, and range in excess of 4000 n mile. This is an interesting combination of characteristics. Operational flexibility for small civil aircraft dictates a maximum takeoff gross weight of 100,000 lb or less. This constraint comes about for a number of reasons. Foremost of these is a broad number of important airports with gross weight limitations set at 100,000 lb. The need for light weight for suppressed sonic boom also drives to gross weights of 100,000 lb or less. Unfortunately, detailed configu￾ration design studies currently show that, for a vehicle at 100,000 lb the maximum allowable cabin size is not compatible with the large cabin business jet standup style cabin. This result is shown in Fig. 15

772 HENNE In Fig.15,three cabin cross sections are shown.The first is for the takeoff gross weight of 100,000 lb.Unfortunately,the cross section current large cabin market leader,the G550(GV).and represents a does not meet minimum standards for a large-cabin aircraft where minimum acceptable cross section deemed to be attractive for the occupants could spend 5 h in the cabin.This risk area is one that long range business aircraft today.Its cabin height is 74 in.The sec- needs additional research to develop a configuration satisfying all ond cross section is for a QSJ configuration that meets performance of the market requirements. and boom requirements.The cross section is acceptable.Unfortu- nately,the takeoff gross weight is in excess of 150,000 Ib.The third cross section is for a smaller configuration sized for a maximum Design Requirements Market requirements,environmental concerns,and program re- G550 TOGW>150K Ib TOGW=100K Ib quirements can all be combined into a cohesive set of design require- ments for a small supersonic civil aircraft.Performance goals such as cruise speed,range,payload capability,and field performance must be met while low noise,low exhaust emissions.and a sonic boom signature deemed acceptable for supersonic overland fight are simultaneously achieved.These requirements are summarized in Fig.16.Also,provided in Fig.16 are the current red/yellow/green Max Fuselage 94.0 93.0 80.9 color assessments of risk associated with the satisfaction of each re- Diameter quirement.The red areas are both associated with sonic boom.In Aisle Height 74.0 75.9 66.0 addition,the certification concern includes the absence of any cer- w/Flat Floor Aisle Height tification regulations for civil supersonic aircraft.Concorde certifi- n/a n/a 68.9 w/Notch cation was accomplished three decades ago through a large number Aisle Width 20.0 20.0 20.0 of special conditions largely reflecting consideration of only the above 25 in Aisle Width 20.0 20.0 15.0 unique Concorde type design.Airworthiness certification standards below 25 in for subsonic aircraft have substantially advanced to higher stan- Seat Width 26.0 26.0 24.0 dards since the time of Concorde certification.Any new supersonic (all dim ensions in inches) type will necessarily need to satisfy higher standard regulatory re- Fig.15 Fuselage cross section comparison. quirements for certification.The yellow assessments are for areas How Far NBAA IFR Range 4,800NM How Fast- Cruise Mach 1.6-2.0 How Much Max Ramp Weight 100,000Lb ● Design Pax Payload 1,600Lb Cabin Size 1,300 Cu Ft(GlI Vol Xsect) From Where- Takeoff Field Length-SL;ISA+20C 6,500Ft ACN,Approach Category,and Design Group 0.99 Cost Engine Life(STBO) >=2,000Hr Effectively Civil Market Price $70-90M Fig.16 Top level QSJ design requirements Fixed Variable Sweep Pros ·Lower Complexity Improved Low Speed Perf. Improved Structural Load Better for Noise Path Improved Subsonic Range ·Greater Fuel Volume Greater High Speed Potential Cons Unacceptable Field Length Increased Complexity (System Requirements(Operational Operational Requirements) Restrictions) More Difficult Certification Poor Subsonic Performance (Reduced Flexibility) ·Weight Penalty Fig.17 Variable wing sweep favored for satisfying QSJ design requirements

772 HENNE In Fig. 15, three cabin cross sections are shown. The first is for the current large cabin market leader, the G550 (GV), and represents a minimum acceptable cross section deemed to be attractive for the long range business aircraft today. Its cabin height is 74 in. The sec￾ond cross section is for a QSJ configuration that meets performance and boom requirements. The cross section is acceptable. Unfortu￾nately, the takeoff gross weight is in excess of 150,000 lb. The third cross section is for a smaller configuration sized for a maximum Fig. 15 Fuselage cross section comparison. Fig. 16 Top level QSJ design requirements. Fig. 17 Variable wing sweep favored for satisfying QSJ design requirements. takeoff gross weight of 100,000 lb. Unfortunately, the cross section does not meet minimum standards for a large-cabin aircraft where occupants could spend 5 h in the cabin. This risk area is one that needs additional research to develop a configuration satisfying all of the market requirements. Design Requirements Market requirements, environmental concerns, and program re￾quirements can all be combined into a cohesive set of design require￾ments for a small supersonic civil aircraft. Performance goals such as cruise speed, range, payload capability, and field performance must be met while low noise, low exhaust emissions, and a sonic boom signature deemed acceptable for supersonic overland fight are simultaneously achieved. These requirements are summarized in Fig. 16. Also, provided in Fig. 16 are the current red/yellow/green color assessments of risk associated with the satisfaction of each re￾quirement. The red areas are both associated with sonic boom. In addition, the certification concern includes the absence of any cer￾tification regulations for civil supersonic aircraft. Concorde certifi- cation was accomplished three decades ago through a large number of special conditions largely reflecting consideration of only the unique Concorde type design. Airworthiness certification standards for subsonic aircraft have substantially advanced to higher stan￾dards since the time of Concorde certification. Any new supersonic type will necessarily need to satisfy higher standard regulatory re￾quirements for certification. The yellow assessments are for areas

HENNE 773 Fig.18 QSJ baseline variable sweep configuration. that need more research and technology development to achieve the been made in the development of sonic boom suppression tech- desired level of performance. nology.Boom suppression technology needs to be flight demon- strated to reduce risk to a point of commercial acceptability Configuration Characteristics Atmospheric chemistry models have advanced to the point of credible analyses of emissions impacts.Atmospheric studies of One of the more significant design considerations that has been aircraft cruise emissions suggest advantageous cruise altitudes evaluated in the development of a configuration to meet the Fig.16 and strongly favor a small vehicle.An aggressive and continu- design requirements is the wing geometry.The introduction of vari- ing research and development program in aeronautical fundamen- able wing sweep geometry offers the potential of satisfaction of tals is sorely needed to support low emissions in future aircraft the diverse high-speed and low-speed requirements.Analyses to designs. date indicate that variable wing sweep is favored.The precedents The small supersonic civil aircraft is seen as an exciting opportu- set with F-111,F-14,and B-1,as well as numerous foreign de- nity finally to provide a successful supersonic transportation system. signs,confirm that this design approach is certainly ready for the It is an opportunity to provide revolutionary capability to a market civil market.As summarized in Fig.17,the positives for variable that values speed.It is an opportunity to provide the long-sought wing sweep outweigh the negatives.The variable sweep wing has first successful supersonic civil aircraft. been a strong factor in the green assessment shown in Fig.16 for takeoff field length.It is fundamental to the data shown in Fig.13 for airport noise estimates.It provides for greater poten- Acknowledgments tial in the high-speed design area for both improvement of super- Special thanks go to R.Wolz,T.Porter,D.Howe, sonic performance and suppression of sonic boom.A Gulfstream T.Conners,J.Salamone,F.Simmons III,and D.Freund of Gulf- baseline QSJ configuration with a variable sweep wing is shown stream Aerospace Corporation who have made significant contri- in Fig.18. butions to the Gulfstream quiet supersonic jet Program.Recogni- tion also goes to R.Wlezien,M.Tang,and P.Coen from NASA Summary for their assistance and encouragement.A special thanks goes to R.Hicks,NASA retired,for his assistance with sonic boom and A significant factor in the growth of small civil aircraft market is supersonic aerodynamic development.Special recognition goes to the value of time.Recognition of the ever-increasing value of time D.Wuebbles and his team at the University of Illinois,Depart- has lead to increased interest in the feasibility of a small supersonic ment of Atmospheric Sciences for their expertise in atmospheric civil aircraft.The step to supersonic speeds offers the potential of a chemistry and modeling and their fleet analyses efforts.Finally. dramatic decrease in travel time.Multiple market research studies special thanks go to D.Maglieri of Eagle Aeronautics,Inc.,for his of a small supersonic civil jet have been conducted.The current amazing experience,knowledge,and intuition in all aspects of sonic perspective indicates there is a significant market potential for a boom. small supersonic civil aircraft,provided supersonic overland flight is achieved.Studies suggest a market size of 300+units over a 10-year period can be expected. References Hindsight suggests that a first truly successful supersonic civil Wolz,R.."A Summary of Recent Supersonic Vehicle Studies at Gulf- aircraft should,in fact,be a small vehicle.Vehicles of the business stream Aerospace."AIAA Paper 2003-0558.Jan.2003. aircraft size provide a much greater opportunity for a successful 2Wlezien.R..and Veitch.L.."The DARPA Quiet Supersonic Platform solution of the technical,environmental,and economic concerns Program,"AlAA Paper 2002-0143,Jan.2002. Successful achievement of technical,environmental,and economic 3.The Potential for The Supersonic Business Jet,"Meridian International objectives with a business jet size vehicle will satisfy growing mar- Research,Aviation House,Wellesbourne Airport,Wellesbourne,Warwick. England,U.K.,March 1999. ket demand and pave the way for future larger and more advanced 4"SSBJ II Airline and Fractional Markets,"Meridian International Re- vehicles. search,Aviation House,Wellesbourne Airport,Wellesbourne,Warwick. Environmental concerns for sonic boom,engine exhaust emis- England,U.K.,July 2000. sions,and airport noise need to be addressed responsibly for any sSmall Supersonic Vehicle Definition and Market Outlook."Teal Group small supersonic civil aircraft design.Significant progress has Corporation,Nov.2002

HENNE 773 Fig. 18 QSJ baseline variable sweep configuration. that need more research and technology development to achieve the desired level of performance. Configuration Characteristics One of the more significant design considerations that has been evaluated in the development of a configuration to meet the Fig. 16 design requirements is the wing geometry. The introduction of vari￾able wing sweep geometry offers the potential of satisfaction of the diverse high-speed and low-speed requirements. Analyses to date indicate that variable wing sweep is favored. The precedents set with F-111, F-14, and B-1, as well as numerous foreign de￾signs, confirm that this design approach is certainly ready for the civil market. As summarized in Fig. 17, the positives for variable wing sweep outweigh the negatives. The variable sweep wing has been a strong factor in the green assessment shown in Fig. 16 for takeoff field length. It is fundamental to the data shown in Fig. 13 for airport noise estimates. It provides for greater poten￾tial in the high-speed design area for both improvement of super￾sonic performance and suppression of sonic boom. A Gulfstream baseline QSJ configuration with a variable sweep wing is shown in Fig. 18. Summary A significant factor in the growth of small civil aircraft market is the value of time. Recognition of the ever-increasing value of time has lead to increased interest in the feasibility of a small supersonic civil aircraft. The step to supersonic speeds offers the potential of a dramatic decrease in travel time. Multiple market research studies of a small supersonic civil jet have been conducted. The current perspective indicates there is a significant market potential for a small supersonic civil aircraft, provided supersonic overland flight is achieved. Studies suggest a market size of 300+ units over a 10-year period can be expected. Hindsight suggests that a first truly successful supersonic civil aircraft should, in fact, be a small vehicle. Vehicles of the business aircraft size provide a much greater opportunity for a successful solution of the technical, environmental, and economic concerns. Successful achievement of technical, environmental, and economic objectives with a business jet size vehicle will satisfy growing mar￾ket demand and pave the way for future larger and more advanced vehicles. Environmental concerns for sonic boom, engine exhaust emis￾sions, and airport noise need to be addressed responsibly for any small supersonic civil aircraft design. Significant progress has been made in the development of sonic boom suppression tech￾nology. Boom suppression technology needs to be flight demon￾strated to reduce risk to a point of commercial acceptability. Atmospheric chemistry models have advanced to the point of credible analyses of emissions impacts. Atmospheric studies of aircraft cruise emissions suggest advantageous cruise altitudes and strongly favor a small vehicle. An aggressive and continu￾ing research and development program in aeronautical fundamen￾tals is sorely needed to support low emissions in future aircraft designs. The small supersonic civil aircraft is seen as an exciting opportu￾nity finally to provide a successful supersonic transportation system. It is an opportunity to provide revolutionary capability to a market that values speed. It is an opportunity to provide the long-sought first successful supersonic civil aircraft. Acknowledgments Special thanks go to R. Wolz, T. Porter, D. Howe, T. Conners, J. Salamone, F. Simmons III, and D. Freund of Gulf￾stream Aerospace Corporation who have made significant contri￾butions to the Gulfstream quiet supersonic jet Program. Recogni￾tion also goes to R. Wlezien, M. Tang, and P. Coen from NASA for their assistance and encouragement. A special thanks goes to R. Hicks, NASA retired, for his assistance with sonic boom and supersonic aerodynamic development. Special recognition goes to D. Wuebbles and his team at the University of Illinois, Depart￾ment of Atmospheric Sciences for their expertise in atmospheric chemistry and modeling and their fleet analyses efforts. Finally, special thanks go to D. Maglieri of Eagle Aeronautics, Inc., for his amazing experience, knowledge, and intuition in all aspects of sonic boom. References 1Wolz, R., “A Summary of Recent Supersonic Vehicle Studies at Gulf￾stream Aerospace,” AIAA Paper 2003-0558, Jan. 2003. 2Wlezien, R., and Veitch, L., “The DARPA Quiet Supersonic Platform Program,” AIAA Paper 2002-0143, Jan. 2002. 3“The Potential for The Supersonic Business Jet,” Meridian International Research, Aviation House, Wellesbourne Airport, Wellesbourne, Warwick, England, U.K., March 1999. 4“SSBJ II Airline and Fractional Markets,” Meridian International Re￾search, Aviation House, Wellesbourne Airport, Wellesbourne, Warwick, England, U.K., July 2000. 5“Small Supersonic Vehicle Definition and Market Outlook,” Teal Group Corporation, Nov. 2002

774 HENNE 6McLean,F.E"Supersonic Cruise Technology,"NASA SP-472. 10Howe.D.,"Engine Placement for Sonic Boom Mitigation,"AIAA Paper 1985. 2002-0148.Jan.2002. 7U.S.Supersonic Commercial Aircraft:Assessing NASA's High Speed 1Howe,D.."Sonic Boom Reduction Through the Use of Non- Research Program,"National Research Council,National Academy Press, Axisymmetric Configuration Shaping."AIAA Paper 2003-0929,Jan.2003. Washington,DC,1997. 12Dutta,M.Patten,K.,and Wuebbles,D.."Parametric Analy- Commercial Supersonic Technology.The Way Ahead,National Research ses of Potential Effects on Stratospheric and Tropospheric Ozone Council,National Academy Press,Washington,DC,2001. Chemistry by a Fleet of Quiet Supersonic Business Jets (QSJs) Carlson,H.W.The Lower Bound of Attainable Sonic-BoomOverpres- Projected in a 2020 Atmosphere,"Study Rept..Dept.of Atmo- sure and Design Methods of Approaching This Limit,"NASA TN D-1494. spheric Sciences,Univ.of Illinois at Urbana-Champaign,Urbana,IL, 1962. Nov.2002

774 HENNE 6McLean, F. E., “Supersonic Cruise Technology,” NASA SP-472, 1985. 7U.S. Supersonic Commercial Aircraft: Assessing NASA’s High Speed Research Program,” National Research Council, National Academy Press, Washington, DC, 1997. 8Commercial Supersonic Technology, The Way Ahead, National Research Council, National Academy Press, Washington, DC, 2001. 9Carlson, H. W., “The Lower Bound of Attainable Sonic-Boom Overpres￾sure and Design Methods of Approaching This Limit,” NASA TN D-1494, 1962. 10Howe, D., “Engine Placement for Sonic Boom Mitigation,” AIAA Paper 2002-0148, Jan. 2002. 11Howe, D., “Sonic Boom Reduction Through the Use of Non￾Axisymmetric Configuration Shaping,” AIAA Paper 2003-0929, Jan. 2003. 12Dutta, M., Patten, K., and Wuebbles, D., “Parametric Analy￾ses of Potential Effects on Stratospheric and Tropospheric Ozone Chemistry by a Fleet of Quiet Supersonic Business Jets (QSJs) Projected in a 2020 Atmosphere,” Study Rept., Dept. of Atmo￾spheric Sciences, Univ. of Illinois at Urbana–Champaign, Urbana, IL, Nov. 2002