AircraftAircraft DesignDesign ClassClass Sam B. Wilson III Chief Visionary Officer AVID LLC www.avidaerospace.com 9 September 2008 TTO Tactical Technology Office 9 Sept.’08 / pg # 2 DesignDesign MethodsMethods What Size? What Shape? 9 Sept.’08 / pg # 3 Design “As Drawn” Computer evaluation of Conceptual Designs “As Drawn” Assumes fixed external mold- lines JSFJSF X-35BX-35B Weight as independent variable - “loop 9 Sept.’08 / pg # 4 closure” IntegrationIntegration Challenge:Challenge: To design a supersonic fighter/attack aircraft that offers the operational flexibility of Short Takeoff and Vertical Landing (STOVL) Need to make the same design compromises as a conventional fighter, plus one: use the available thrust in a manner that allows a controlled vertical landing This single added constraint requires a more systematic approach to the design of an aircraft. 9 Sept.’08 / pg # 5 V/STOLV/STOL AircraftAircraft DesignDesign ProcessProcess Step 1 Define wing & horizontal stabilizer geometry Located engine “vertical thrust” center with respect to aerodynamic center 9 Sept.’08 / pg # 6 Ref NASA CR-177437 V/STOLV/STOL AircraftAircraft DesignDesign ProcessProcess Step 2 Add minimum length inlet/diffuser Add cockpit and forebody 9 Sept.’08 / pg # 7 Ref NASA CR-177437 V/STOLV/STOL AircraftAircraft DesignDesign ProcessProcess Step 3 Add vertical tails Assign location dependent masses landinglanding geargear flightflight controlscontrols radarradar 9 Sept.’08 / pg # 8 Ref NASA CR-177437 V/STOLV/STOL AircraftAircraft DesignDesign ProcessProcess Step 4 Add Payload bays / weapon hardpoints Add fuel tanks Assign location independent masses ServiceService centerscenters AAvionicsvionics APUAPU 9 Sept.’08 / pg # 9 Ref NASA CR-177437 V/STOLV/STOL AircraftAircraft DesignDesign ProcessProcess Step 5 Add lead weight ballast! CGCG tootoo farfar forwardforward VerticalVertical thrustthrust centercenter tootoo farfar aftaft 9 Sept.’08 / pg # 10 OverviewOverview ofof StudyStudy Description of four candidate propulsion systems which can be based on a single gas generator First order effects of the four propulsion systems on the sizing of a STOVL fighter 9 Sept.’08 / pg # 11 DesignDesign MissionMission 9 Sept.’08 / pg # 12 STOVLSTOVL LiftLift SystemsSystems StudyStudy Unscaled Propulsion System Weights 5000 4000 front nozzle 3000 ducts C & A 2000 rear/ventral Augmentor Weight (lb) gas generator 1000 0 RALS RULS MFVT L+L/C 9 Sept.’08 / pg # 13 ThrustThrust toto WeightWeight DefinitionsDefinitions (review)(review) Engine T/W = Uninstalled Max A/B Thrust CTOL Engine Weight System T/W = Installed Max A/B Thrust Total Propulsion System Weight Lift System T/W = Balanced Vertical Thrust Total Propulsion System Weight 9 Sept.’08 / pg # 14 STOVL Lift System Performance System Thrust to Weight 10 8 6 Vertical Thrust 4 Max. Aug Thrust Thrust / Weight 2 0 R A L S R U L S MFVT L+L/C 9 Sept.’08 / pg # 15 STOVLSTOVL LiftLift SystemSystem BreakoutBreakout Group Weights 35000 30000 25000 Fuel 20000 Payload Fixed Equip. 15000 Propulsion Weight (lb) 10000 Airframe 5000 0 R A L S R U L S MFVT L+L/C 9 Sept.’08 / pg # 16 STOVLSTOVL GrossGross WeightWeight SensitivitySensitivity Design Point Sensitivity 10% change in manuver performance 5 4 3 2 Percent Change 1 0 R A L S R U L S MFVT L+L/C 9 Sept.’08 / pg # 17 CruiseCruise EngineEngine ThrustThrust forfor L+L/CL+L/C Thrust Distribution 30,000 Lift engine at .42 L C.G. at .58 L 25,000 20,000 15,000 Lift engine Thrust Thrust (lb) 10,000 L/C eng Vert. Thrust 5,000 0 0.5 0.6 0.7 0.8 0.9 1.0 9 Sept.’08 / pg # 18 Aft Nozzle Location HoverHover BalanceBalance Thrust Required for Vertical Landing 45,000 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000 - 0.42 0.46 0.50 0.54 0.58 0.62 0.66 0.70 0.74 Station Location 9 Sept.’08 / pg # 19 OffOff DesignDesign PerformancePerformance Fallout Performance RALS RULS MFVT L+L/C Ps @ M=1.50, 30k' 410 1123 861 583 Nz @ M=0.60, 20k' 4.05 4.04 4.03 4.05 Nz @ M=1.20, 40k' 3.14 3.77 3.59 3.34 9 Sept.’08 / pg # 20 ConclusionConclusion forfor LiftLift EnginesEngines If high maneuver performance and/or dry super- cruise is required, lift engines have limited value (mission dependent) Lift System thrust to weight is not a strong function of engine T/W for many engine configurations Factors other than mission performance will be necessary to choose a propulsion system 9 Sept.’08 / pg # 21 9 Sept.’08 / pg # 22 CNACNA AirAir PanelPanel StudyStudy - Tactical Air Assets for Carrier Task Force Fighter & Attack Aircraft vs. Multi-Mission Aircraft STOVL vs. Conventional Carrier Based Aircraft No Utility Aircraft Assessments - Used STOVL Strike Fighter TOR Missions Latest Statement of Future Naval Mission Requirement Multi-Mission (F/A & SSF) Do All Missions Subsonic Attack Aircraft Point Designed for Air to Ground "Blue Water" Fighter Optimized for Fleed Air Defense - Emphasis on Time Based Technology Trends Baseline was US/UK ASTOVL "1995 TAD" Assumptions “1990 TAD” Timeframe Allows for "What is Available" 9 Sept.’08 / pg # 23 NASA-AmesNASA-Ames StudyStudy PlanPlan Technology Availability Date Common: Engine Cycle, Weapons, Avionics, etc. 1990-TAD 1995-TAD Radar Absorbing Material + 0% + 5% Internal Weapons Carriage No Yes 1.5M Supersonic Cruise A/B “Dry” Design Load Factor 7.5 9.0 Technology Factor 90% 85% Propulsion System T/W ~12 ~15 9 Sept.’08 / pg # 24 DifferentiatorsDifferentiators ”1990 TAD” Aircraft Class Fighter Multi-Mission Attack Structural Tech. Factor -10% -10 % -10% Design Load Factor 6.5 g 7.5 g 6.5 g Survivability Impacts No No No Dry Super-cruise No No No Plan form Variable Standard Standard Wing Pivot +30% 0 0 Tail Surfaces Standard Standard Standard 9 Sept.’08 / pg # 25 DifferentiatorsDifferentiators "1995 TAD" Aircraft Class Fighter Multi-Mission Attack Structural Factor -15% -15 % -15% Design Load Factor 9.0 g 9.0 g 6.5 g Survivability Impacts No Yes Yes Dry Supercruis Yes Yes No Planform Variable Diamond Flying Wing Wing Pivot +30% 0 0 Tail Surfaces Conventional Conventional None 9 Sept.’08 / pg # 26 AmesAmes CNACNA StudyStudy DescriptionDescription Three Aircraft Classes Direct-Lift STOVL Sea-Based (“Cat / Trap”) Land-Based Two Technology Timeframes 1990-TAD 1995-TAD Philosophy ACSYNT - Design Synthesis Code 9 Sept.’08 / pg # 27 BaselineBaseline DesignDesign MissionMission 2 min combat 1.5M at 50000 ft 400 nmi cruise Best Altitude and Mach 150 nmi dash 1.5M at 50000 ft High Value Stores Retained for Landing 2 Long-Range, Air-to-Air Missiles 2 Short-Range, Air-to-Air Missiles Gun and Ammo 60 minutes loiter Best Mach at 35000 ft Loiter 0.3M at Sea Level 250 nmi cruise 0.85M at Sea Level 9 Sept.’08 / pg # 28 AircraftAircraft ClassClass DetailsDetails STOVL Sea-Based Land-Based Fuselage Structure 0 + 30 % 0 Landing Gear Structure 0 + 30 % 0 Carrier Approach No Yes No Propulsion Weight + 47% 0 0 Landing Hover T/W 1.16 N/A N/A Reaction Control System Yes No No Duct Volume Penalty ~10% 0 0 Loiter in Pattern 10 min 20 min 20 min 9 Sept.’08 / pg # 29 PropulsionPropulsion SystemsSystems Conventional Direct-Lift STOVL 9 Sept.’08 / pg # 30 AircraftAircraft EvolutionEvolution 1995-TAD 1990-TAD 9 Sept.’08 / pg # 31 BaselineBaseline AircraftAircraft 100000 1990-TAD 1995-TAD 80000 60000 40000 Takeoff Weight (lb) 20000 0 STOVL STOVL Sea-Based Sea-Based Land-Based Land-Based 9 Sept.’08 / pg # 32 AugmentationAugmentation inin HoverHover 100,000 1990-TAD STOVL Baseline Derivative 80,000 60,000 40,000 Takeoff Weight (lb) 20,000 0 9 Sept.’08 / pg # 33 Sea-Based Land-Based STOVL DryDry Super-cruiseSuper-cruise RequiredRequired 100,000 Derivative 1990-TAD Conventional Baseline 80,000 60,000 40,000 20,000 Takeoff Gross Weight (lb) 0 9 Sept.’08 / pg # 34 Sea-Based Land-Based STOVL 1990-TAD1990-TAD GrowthGrowth FactorFactor 25 Sea-Based 20 STOVL Design Mission 15 Radius 10 Growth Factor 5 0 0 100 200 300 400 500 600 700 Mission Radius (nm) 9 Sept.’08 / pg # 35 1995-TAD1995-TAD GrowthGrowth FactorFactor 25 Sea-Based 20 STOVL Design Mission Radius 15 10 Growth Factor 5 0 0 100 200 300 400 500 600 700 Mission Radius (nm) 9 Sept.’08 / pg # 36 RequiredRequired HoverHover ThrustThrust MarginMargin 1995-TAD STOVL 100000 80000 60000 Sea-Based 40000 Land-Based Baseline STOVL Takeoff Gross Weight (lb) 20000 1.16 T/W requirement 0 1.15 1.2 1.25 1.3 1.35 T/Whover 9 Sept.’08 / pg # 37 9 Sept.’08Sept.’08 / pg # 3838 9 Sept.’08 / pg # 39 9 Sept.’08 / pg # 40 9 Sept.’08 / pg # 41 9 Sept.’08 / pg # 42 STOVL Baseline Aircraft Direct Lift Remote Fan L+L/C T.O. Gross Weight (LB) 36,331 36,866 39,679 Length (ft) 48. 54. 54. Wing Area (ft2) 345. 400. 440. Span (ft) 29.6 32.8 35.1 Thrust (Vertical landing) 29,289 42,142 47,102 Thrust (SLS Dry) 29,289 26,02127,595 Propulsion Weight (LB) 8,381 8,419 10,014 Engine Weight (LB) 7,532 6,723 7,097 Fuel Weight (LB) 11,387 10,698 11,207 9 Sept.’08 / pg # 43 STOVL Aircraft (Ratios) Direct Lift Remote Fan L+L/C Growth Factor 3.20 2.37 3.52 Aspect Ratio 2.5 2.6 2.8 Wing Loading (LB/ft2) 105.3 92.2 90.2 Vertical Thrust/WPS 3.49 5.01 4.70 Dry Thrust/TOGW 0.81 0.71 0.70 Max Thrust/TOGW 1.30 1.14 1.12 ESF 1.21 1.08 1.14 Prop.