Towards a renewal of supersonic transport? Former Head of Airbus Propulsion Centre By Gérard Théron Member of AAE Wednesday 9 October - Académie Royale de Belgique - Brussels Summary In the past few years, at least three supersonic aircraft projects have been launched by unknown start-ups to "replace" Concorde. How do they shape up? Boom team Concorde: history et characteristics Challenges for a potential successor Advanced studies (commercial aircraft): 1975-1990s European program High Speed AirCraft: 2004-2009 New projects: Boom, Aerion, Spike Performance aspect Program aspect Conclusion Gérard THERONWednesday 07/11/2018 9 octoberVers - Académie un renouveau Royale du transport de Belgique supersonique? - Brussels 2 Development program: 1962-1976 Programme launched in 1962 and developed by teams that had already designed and flown military and civil aircraft (Trident and Caravelle in France, BAC 111, Vickers VC10 in England): used all existing design office and test means built by States (ONERA,… ) no financial constraints mobilized the best European civil aeronautic teams and the most powerful computation means available no environmental constraints. The difficulties encountered to achieve the target (Paris-New-York with 100 passengers) led to major adjustments to definition during the 14 years of development. Take-off thrust was increased by boosting the post combustion in particular. 2 March 1969 6 December 1973 Prototype: 135t, L = 51.8m, W = 23.8m Series: 185.07t, L = 61.66m, W = 25.6m Wednesday 9 October - Académie Royale de Belgique - Brussels Concorde Only supersonic commercial aircraft. Only aircraft able to fly Mach 2 for over 2 hours. Only supersonic aircraft able to fly Paris (or London)-New-York, about But: 6000km, with full payload (100 passengers). only 250,000 hours flight hours on 13 aircraft over 27 years 800 kg of jet fuel per passenger to achieve New-York take-off and landing noise unacceptable today unable to fly over populated areas at supersonic speed convenient for westward flights, less so for eastward travel surface temperature over 100°C (materials but also systems) very high operational costs for a take-off weight of 185t, to reach NY. Crew Wednesday 9 October - Académie Royale de Belgique - Brussels 4 Concorde B In 1976, Aérospatiale & BAC planned to develop a derivative aircraft: Concorde B, with: improved aerodynamics: . 12 to 13% take-off lift/drag ratio . 7% in cruise . but +1855kg derivative engines . 0.25 bypass ratio without post combustion . -2.7% cruise SFC . -8 to 10 EPNdB for take-off . but +5098kg weight reduction through composite material introduction (-1088kg). The resulting aircraft would have seen its range increased by 500NM (900km) with take-off noise reduction and a slight TO weight increase The development would have lasted 5 years. Wednesday 9 October - Académie Royale de Belgique - Brussels Take-off and landing noise levels unacceptable today CERTIFIED NOISE 3° 3 control- points perceived Noise for standard procedure, MTOW, MLW Lateral and adjusted thrust Cumulative noise: sum of Approach Flyover (~4°) 3 noise levels in EPNdB 370 Production aircraft cumulative noise levels 350 Concorde 90 EPNdB 185t 60 EPNdB 330 B707-300 310 30 dB/point: Chap 14 limit for 4 engine aircraft acoustic 290 747-8 A380 power*1024 270 A350-9 10 Turbofan BPR 9 à 10 Cumulative noise Cumulative EPNdB Re-engined medium range aircraft MTOW (t) 250 " neo & MAX " turbofans BPR 10 à 12 50 Wednesday 9 October - Académie Royale de500 Belgique - Brussels 800 kg fuel per passenger to reach New-York Fuel Consumption: New CO2 standard ICAO, subsonic aircraft CO2 certification Metric value:1/( SAR*RGF) versus MTOW Kilometric fuel 4 SAR: Specific Range (km/kg fuel burnt) Concorde consumption for roughly 3,5 RGF: (cabin floor area/1m2) ^0.24 the same cabin floor 3 area was 4 times higher 2,5 than the A320neo, which 2 1,5 carries 50% more Metric value passengers over the 1 limit (new type design) commercial aircraft same distance. 0,5 0 Business jets 0 100 200 300 400 500 600 700 Max takeoff weight (tonnes) Wednesday 9 October - Académie Royale de Belgique - Brussels Summary Concorde: history and characteristics Challenges for a potential successor Advanced studies (commercial aircraft): 1975-1990s European program High Speed AirCraft: 2004-2009 New projects: Boom, Aerion, Spike Performance aspect Program aspect Conclusion Wednesday 9 October - Académie Royale de Belgique - Brussels Cruise flight level thrust-drag balance and definitions LIFT AERODYNAMIC FORCES THRUST DRAG SPEED AIRCRAFT WEIGHT SPECIFIC CONSUMPTION Cs (Mg) Fuel consumption/ Thrust: LIFT/DRAG RATIO : Engine quality: function of f component efficiencies, thermodynamic Aircraft aerodynamic quality: cycle and aircraft speed Function of the geometry and aircraft (kg/daN.h) speed. Landing weight Aircraft speed Lift / drag ratio Takeoff+ fuel weight burn Aircraft range = XX ln g Specific consumption Landing weight Wednesday 9 October - Académie Royale de Belgique - Brussels Some orders of magnitude: Lift over drag ratio A320 Concorde Medium Supersonic range Gliders fighters 10 20 30 Regional Long aircraft Range ATR A350 The geometric characteristics of aircraft are the result of optimisations taking into account speed, wing weight, fuel capacity and targeted range. Current CFD computations will enable improved optimisation of aerodynamic shape without dramatic changes to lift/drag levels. Wednesday 9 October - Académie Royale de Belgique - Brussels Some orders of magnitude: specific fuel consumption Turbojet engine Olympus L/D ~ 10 Moteur Leap 1A: BPR=11 L/Φfan= 2.4 Flux secondaire Flux primaire Consommations spécifiques de moteurs Specific fuel consumption 2 JT8D-7B BPR 1,07 varies with: TFE731-3B-100 2,8 1,6 • engine thermal efficiency CFM56-5A3 BPR 5 (overall pressure ratio, 1,2 CFM56-5C4 BPR 7,1 components and internal GE90-85B BPR 8,4 0,8 temperature) Potentiel Concorde sec INST • 0,4 pour moteur Mlala BPR 0,3 propulsive efficiency (BPR futur, BPR 1 à 2 and aircraft Mach number) Concorde PCINST Consommation spécifique (lbs/lbs.h)Consommationspécifique 0 Mach HISAC 0 0,5 1 1,5 2 2,5 Gérard THERONWednesday 07/11/2018 9 OctoberVers un - Académierenouveau du Royaletransport de supersonique? Belgique - Brussels 11 Some orders of magnitude: Take-off noise Sound power increases mainly with jet speed: (d2*V8) or thrust * V6 (Vx2: Noise x 64) Noise evolution function of jet speed (same thrust) 10 Same technological level for Concorde thrust Concorde with PC 1 0 BPR: Ws/Wp -10 secondary 1/32 Primary 10 power -20 Acoustic Secondary turbojet noise with PC (dB) By-pass ratio 5 1/1024 -30 -40 0 Noise difference/Noise tur -50 Jet speed during takeoff (m/s) 0 200 400 600 800 1000 1200 BPR ratio: secondary airflow going through the fan over the primary airflow going through the compressor, heated in the combustion chamber and ejected through the nozzle after providing the necessary energy thanks to the turbines Wednesday 9 October - Académie Royale de Belgique - Brussels Some orders of magnitude: Take-off noise Noise increases mainly with jet speed: (d2*V8) or thrust * V6 Size & weight function of jet speed (same thrust) 10 Same technological level for Concorde thrust Concorde with PC 0 10 Noise Front area / -10 8 front area turbojet -20 PPS PPS 6 / turbojet noise with PC (dB) size Weight PPS weight / -30 4 PPS weight -40 2 turbojet Noise difference/Noise tu -50 Jet speed during takeoff (m/s) 0 0 200 400 600 800 1000 1200 To achieve a noise level close to the latest subsonic aircraft with the same take-off thrust, the PPS would need an air inlet 5 to 6 times larger and would be 6 to 9 times heavier than for a turbojet. Wednesday 9 October - Académie Royale de Belgique - Brussels To reduce overland sonic boom During cruise, supersonic aircraft produce a “sonic boom” (noise and overpressure) perceived on the ground, which led to a ban on flight over populated areas. Numerous studies are currently underway, essentially in the US, to reduce this effect, with two possible approaches: Concorde Altitude 15000 m Mach 2 the use of atmospheric characteristics∆p – = pressure 1 hPa and∆ tempet = 300rature millisecondes gradients – to absorb the boom, up to Mach 1.1 toLa 1.2 surpression(e.g. the et Aerion la surface project) de la nappe impactée sont fonction du Mach, de l’altitude et de la forme de l’avion. the use of specific aerodynamic shapes to limit the boom to an acceptable level,Du fait que la résultante générale des forces de Machup 2 to Mach 1.4 – 1.5 pression sur le sol équilibre le poids de l'avion et que (e.g. NASA L.M. QueSST prototype). ces forces de pression s'exercent sur une surface limitée par la trace au sol des nappes avant et arrière, ∆t les deux sauts de pression avant et arrière ne peuvent According to a NASA paper of May 2012, this wouldêtre annulés que si le poids de l'avion est nul, ce qui lead to prohibitive fuselage length – rend illusoire toutes les tentatives de suppression du 244 m for a 30-80 passenger aircraft – bang. JC Wanner and a small aspect ratio. The possible speed above populated areas, according to the literature, would clearly be lower than Mach 2. Gérard THERONWednesday 07/11/2018 9 OctoberVers un - Académierenouveau du Royaletransport de supersonique? Belgique - Brussels 14 Sommaire Concorde: history and characteristics Challenges for a potential successor Advanced studies (commercial aircraft): 1975-1990s European program High Speed AirCraft: 2004-2009 New projects: Boom, Aerion, Spike Performance aspect Program aspect Conclusion GérardGérard THERONTHERONWednesday 07/11/201807/11/2018 9 OctoberVers un - AcadémierenouveauVers un renouveau du Royaletransport du de supersonique? transport Belgique supersonique? - Brussels 1515 Challenges for a successor To comply with the certification requirements in force at aircraft launch date: design environmental (?): to reduce airport and cruise (bang) noises and allow flight over populated areas at supersonic speeds to significantly reduce greenhouse emissions.