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Mission Statement Design Requirements Aircraft Concept Selection Advanced Technologies / Concepts Engine / Propulsion Modeling Constraint Analysis / Constraint Diagram Sizing Studies Initial Center of Gravity, Stability and Control Estimates Summary of Aircraft Concepts 2
To design an environmentally responsible aircraft for the twin aisle commercial transport market with a capacity of 400 passengers, NASA’s N+2 capabilities, and an entry date of NASA’s N+2 technology benefits include: Reducing cumulative noise by 42 dB below Stage 4 Reducing take-off and landing NOx emissions to 75% below CAEP6 levels Reducing fuel burn by 50% – relative to “large twin-aisle performance” ( LR) Reducing field length by 50% relative to the large twin-aisle 3
Requirements Threshold 4 RequirementsThresholdTargetCurrent Cruise Mach Range 3,000 nmi4,000 nmi Field Length (at sea level, MTOW) 8,300 ft5,800 ft6,500 ft Field Length 14K ft, +15°F) 18,000 ft9,000 ft11,100 ft Fuel Burn* 33% reduction50% reduction**- NOx Emissions 50% below CAEP 675% below CAEP 6**- Noise Reduction 32 dB cum. below Stage 4 42 dB cum. below Stage 4** - Passenger Capacity *Fuel burn reductions relative to B LR ** NASA ERA goal
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The “Pocket Protectors” (2 Variations UDF or GTF) 6 Pros Increased aerodynamic efficiency for lower drag Decreased noise with engines mounted on top Lighter structure Cons Increased manufacturing complexity Increased maintenance costs
7 The “Side Part” Pros Conventional design Decrease manufacturing cost Decrease maintenance cost Increase noise shielding Cons Not as efficient as a Blended Wing Body design
8 The “Suspenders” Pros Semi-blended wing design Circular pressure vessels Maintenance and manufacturing complexity not as high as a BWB design Cons Higher drag from increased surface area
9 The “Pocket Protectors” The “Side Part” The “Suspenders”
10 Requirements UDF GTF Composites Wingtip Technology Fly By Wireless Trailing Edge Brushes Electric Actuators Laminar Flow Control Active Noise Cancellation Fuel Burn Exterior Noise NOX++ Field Length Empty Weight Cruise Speed- Manufacturing Cost Maintenance Cost Pax/Crew Comfort- + + Layout Complexity Stability & Maneuverability Minimum Ground Time Aesthetics Sigma
Un-Ducted Fan (UDF) Offering minimal fuel consumption Double digit SFC 30% Reduction in fuel consumption and greenhouse gases Offering speed and performance of a turbofan Bigger in size, noisy, safety issues Geared Turbofan (GTF) 12% reduction in fuel consumption 35-50% reduction in CO 2 and NOx 50% reduction in noise Bigger in size Fuel consumption is an issue 11
12 ConceptsT/TOGWThrust RequiredTOGW Engines Required Direct-Drive Engines Required Pocket Protectors With UDF Engine Pocket Protectors With GTF Engine Side Part UDF Engine Suspenders UDF Engine GTF 32K) UDF (same as GTF) Direct-Drive (GE90-115B) ,300
13 Constraint assumptions L/D = 23.9 C L max = 2.16 C D0 = e = 0.9 AR = 12 α cruise = α loiter = V cruise = 0.8 M V TO = ft/s V approach = ft/s Pocket Protector
14 Altitude (ft) Mach Aspect Ratio TO Ground Roll (ft) Braking Ground Roll (ft) W o /S (lb/ft 2 ) T SL /W o Altitude (ft) Mach Aspect Ratio TO Ground Roll (ft) Braking Ground Roll (ft) W o /S (lb/ft 2 ) T SL /W o Pocket Protector High Hot Operating Conditions : H = 14K + 15° Normal Operating Conditions
15 Constraint assumptions L/D = 19.7 C L max = 1.8 C D0 = e = 0.8 AR = 9 α cruise = α loiter = V cruise = 0.8 M V TO = ft/s V approach = ft/s Side Part
16 Altitude (ft) Mach Aspect Ratio TO Ground Roll (ft) Braking Ground Roll (ft) W o /S (lb/ft 2 )T SL /W o Altitude (ft) Mach Aspect Ratio TO Ground Roll (ft) Braking Ground Roll (ft) W o /S (lb/ft 2 )T SL /W o Side Part - Normal Operating Conditions High Hot Operating Conditions- H = 14K +15°
17 Constraint assumptions L/D = 21.8 C L max = 2.45 C D0 = e = 0.75 AR = 10.5 α cruise = α loiter = V cruise = 0.8 Mach V TO = sea level V approach = sea level Suspenders
18 Altitude (ft) Mach Aspect Ratio TO Ground Roll (ft) Braking Ground Roll (ft) W o /S (lb/ft 2 ) T SL /W o Altitude (ft) Mach Aspect Ratio TO Ground Roll (ft) Braking Ground Roll (ft) W o /S (lb/ft 2 ) T SL /W o Suspenders - Normal Operating Conditions High Hot Operating Conditions- H = 14K +15°
19 Simple to Initial L/D calculations implement results from trade studies Component weight build-up method included in code (Raymer, eqs – 15.59) Component build-up technique underway for drag prediction (Raymer, eq ) Best current predictions ConceptsTOGW (lb)OEW (lb)W fuel (lb) The “Pocket Protectors” 235,66091,54054,720 The “Side Part” 251,96097,48065,070 The “Suspenders” 242,83094,16059,270
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21 Concept Center of Gravity (% a/c length) Static Margin Threshold Static Margin Target Pocket Protector53%5%8% Side Part61%5%8% Suspenders59%5%8%
22 Tailless Concepts – Aerodynamic Center Location – Wing Sweep Tradeoffs Traditional Tail Concepts – Tail Area
Implementing New Technologies Geometry Sizing -Component weight distribution -Drag build-up Stability Analysis Internal layout and subsystems Noise prediction Concept refinement 23