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