Transcript of 1. Outline I. Mission Statement II. Design Requirements III. Concept Selection IV. Advanced...
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- Outline I. Mission Statement II. Design Requirements III.
Concept Selection IV. Advanced Technologies and Concepts V. Engine
Modeling VI. Constraint Analysis VII. Most Recent Sizing Studies
VIII. Center of Gravity and Stability Estimates IX. Summary 2
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- Mission Statement Bring aircraft developments into the modern
age of environmental awareness by means of innovative design and
incorporating the next generation of technologies and
configurations to meet NASAs ERA N+2 guidelines. Reduce operating
cost in face of rising fuel prices and consumer pressures to reduce
fares. 3
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- Design Requirements 4
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- Concepts Overview Conventional with improvements Tube &
Wing Hybrid Blended Body Fuselage-Wing Fairing Asymmetric Twin
Fuselage Two Tubular Fuselages 5
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- Concept Generation 6
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- Concept Selection 7
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- Concepts for Further Study Hybrid Blended Body (HBB) Advantages
Increased aerodynamic efficiency Increased enclosed volume Shorter
take-off capabilities Increased noise shielding Disadvantages
Manufacture cost Development cost Increased maintenance cost from
engine support equipment 8
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- Concepts for Further Study Asymmetric Twin Fuselage Advantages
Increased passenger comfort Increased airliner options for
passengers High aspect ratio without weight penalty More engine
placement options Fuselage noise shielding Disadvantages Increased
wetted area Asymmetric aerodynamic loading Airport adaptability
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- Dimensions Total Length: 120 ft Total Width: 18.6 ft Cabin
Length: 87 ft Cabin Width: 18 ft Reference: www.seatguru.com 190
Economy Class Passengers 21 First Class Passengers Hybrid Blended
Body Dimensions and Layout 10 216 in 118 in 98 in 4 in
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- Twin Body Dimensions and Layout Dimensions Large:Small: Total
Length: 143.4 ft Total Length: 75 ft Total Width: 11.08 ft Total
Width: 9.08 ft Cabin Length: 98 ft Cabin Length: 23 ft Cabin Width:
10.42 ft Cabin Width: 8.42 ft Reference: www.seatguru.com 180
Economy Class Passengers 15 First Class Passengers Storage / Cargo
Space Large Body 11
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- New Technologies Composites Engine Selection Propfan Geared
Turbofan Electric Assisted Take-Off Hybrid Laminar Flow Control
Boundary layer control Engine-Air Brake / Quiet Drag Applications
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- Laminar Flow Technologies Source:
http://www.nasa.gov/centers/dryden/pdf/88792m ain_Laminar.pdf
Source: http://www.aviationweek.com/media/images/
awst_images/large/AW_09_20_2010_3506A.ht ml 13
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- -Effects --Researchers at Langley Research Center calculated
that implementing Hybrid Laminar Flow Control to a 300 passenger
twin-engine subsonic aircraft to allow for 50% laminar flow on the
top of the wings and on both sides of the tail. -15% reduction in
block fuel -50% laminarity translates to 5-7% total drag reduction
Source:
http://www.nasa.gov/centers/dryden/pdf/88792main_Laminar.pdf
Laminar Flow Technologies 14
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- Engine Air Brake Source:
http://ns1.nianet.org/workshops/docs/QA/presentations/FSIS/Spakovsky.pdf
Integrate swirl vanes into the mixing duct Swirling exhaust flows
can generate drag quietly demonstrated drag coefficient near one at
~44 dBA full-scale Engine air-brake application for quiet, slow /
steep approach profiles (estimate up to 6 dB for 3 degree change in
glideslope) 15
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- Induced Drag Management Source:
http://ns1.nianet.org/workshops/docs/QA/presentations/FSIS/Spakovsky.pdf
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- Engine Types Geared Turbofan with Electric Assist
Contra-Rotating Propfan with Electric Assist Reference:
airforceworld.com Reference: memagazine.asme.org and Pratt &
Whitney Dependable Engines Advantages Decrease fuel consumption by
16% gate to gate Decreased Nox Emissions by 50% Reduced Noise by
15dB Multiple Energy Storage Options Advantages Increased Fuel
Efficiency 30% Decreased Emissions Multiple Energy Storage Options
Disadvantages Increased Weight due to gearbox Disadvantages
Increased Noise Compared to a High Bypass Turbofan 17
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- Propulsion Modeling Thrust is dependent upon Engine size Mach
Altitude Throttle Position Process 1.Determine Required Engine size
Rubber Engine From Take-off or Climb Constraint 2.Fit Altitude and
Mach Curves From NASAs EngineSim 1.7 3.Interpolate between Curves
to find SFC 18
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- Engine Size -Turbofan engine empirical data -Engine weight,
length, diameter and fan diameter versus dry thrust. -Curve fit
function Data from http://www.jet-engine.net/civtfspec.html 19
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- Engine dimension DimensionsEstimation Engine Weight7530 lb
Engine Length145 in Engine Diameter83 in Fan Diameter80 in Data
from http://www.jet-engine.net/civtfspec.html 20
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- Determining SFC NASAs Engine Sim Interpolations at 25,000
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- Electric Assisted Take-Off A n Energy Approach Energy Density
Variance Jet-A: 18700 BTU/lbm Lithium Polymer: 336 BTU/lbm Total
Take-Off Kinetic Energy Constant Substitute Turbine Energy with
Electric Energy Smaller Turbine Engine may be obtained This
Technology dependent on Constraint Diagram Mechanics and
Thermodynamics of Propulsion 2 nd ed. Hill, P. and Peterson, C.
Emerging Power Batteries 22
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- Performance Constraints Basic Assumptions Constraint Diagrams
Boeing 757 Hybrid Blended Body Concept AsymmetricTwin Fuselage
Concept Constraint Analysis & Diagrams Constraint Analysis
performed on: 23
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- Major Performance Constraints Top of Climb Drag of Aircraft, AR
Sustained Subsonic 2G Maneuver Drag of Aircraft, AR Takeoff Ground
Roll C L Max for Takeoff, AR, Drag of Aircraft, Takeoff Distance
Second Segment Climb C L Max for Takeoff, AR, Drag of Aircraft
Landing Ground Roll C L Max for Landing, Landing Distance 24
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- Datum Basic Assumptions Datum ConstraintsDatum Results C L Max
Takeoff1.5 C L Max Landing1.6 Max Cruise0.75 Induced Drag
Coefficient0.015 Oswald Efficiency0.8 Aspect Ratio7.8 Takeoff
Ground Roll6,000 ft. Landing Ground Roll3,000 ft. Cruise
Altitude32,000 ft. Boeing 757 Datum: T SL /W = 0.33 & W O /S =
135.18 25
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- Datum Constraint Diagram 26
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- Constraint Diagram Observations *T/W NegativeW/S (lb/ft2)
Positive T/W PositiveW/S (lb/ft2) Negative IncreaseDecreaseAffects
CL Takeoff T/W W/S T/W W/S Aerodynamics, Structures, Propulsion CL
LandingW/S W/S Aerodynamics, Structures Take off Ground Roll
Distance W/S W/S Structures Landing Ground Roll Distance W/S W/S
Structures Oswald EfficiencyT/W T/W Aerodynamics, Structures
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- Resulting Feasibility Increasing CL Landing, Ground Roll, e
improve upon datum Blended Wing Body Concept Setting computed AR,
T/W increases, W/S increases Twin Fuselage Concept Setting computed
AR, T/W decreases, W/S decreases 28
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- Significant Differences Between Assumptions and Technology
Factors Twin Fuselage Concept With larger AR and wetted area,
larger C L Takeoff & Landing required and increased C DO
Alternatively, extend runway limitations Blended Wing Body Concept
With top-sided engine placement, increased C L because of
disturbances from engine With lower AR, can make up efficiency with
higher Oswald efficiency factor Smaller Parasite Drag leads to
smaller C DO T/W W/S (lb/ft 2 ) C L Landing C L TOAR Ground Roll
(TO/Land) e C DO Hybrid Blended Body 0.341201.651.556.95000/3000
ft.0.850.01 Twin Fuselage0.331252.42.1 10.2 2 4000/2000 ft.0.80.02
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- Aircraft Sizing Capabilities Status: Working Weight Build-Up
Complete Simple Drag Polar Mission Profile Engine Modeling Concept
Application 3 variations of Sizing Algorithms 757-200, Hybrid
Blended Body, Asymmetric Twin Fuselage 32
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- Structures Build Up Empty Weight Estimates Wing, Vert/Horiz
Tail, Fuse, Engines, Nacelles, Landing Gear, Avionics, Control
Systems, etc. Composite structure was taken into account with a
fudge factor (Raymer) 0.9 for wing 0.88 for tails 0.95 for fuselage
Twin Fuselage Considerations: Distribution of weight between
fuselages Passenger weight is also taken into account 757-200HBB2
Fuse Operating Empty Weight [lbs] 126,000110,000154,000 This output
compared to the actual EOW of 127520 lbs results in a difference of
~1%. *airliners.net Large Fuselage: 41000 lbs Small Fuselage: 51000
lbs Without passengers 33
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- Drag Estimate Results for Concept Comparison Twin Fuselage 757
Hybrid Blended Body 21400 lbf 17400 lbf 14900 lbf -Values represent
the drag estimate based on the parameter files with cruise
conditions for each individual case - Plan to obtain more accurate
results when the Drag Code is changed to accommodate for more
Geometry and Sizing Variables using the Component Buildup Method
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- Current Weight Conclusions HBB modeled as having a lower AR,
and lower S wet /S ref which is equivalent to a lower skin friction
drag Two fuselage modeled as higher AR and higher wetted area. Both
propulsion models have a 16% decrease in SFC. 35 757-200HBB2 Fuse
OEW (lbs) 130,000116,500154,000 Wfuel (lbs) 72,50058,90066,900 GTOW
(lbs) 252,000225,500271,000
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- Concept Geometry Inputs 36 Boeing 757HBBTwin Fuselage
AR7.86.98.5 Swet/Sref5.735.376.22 e.81.84 In addition to the
component weight buildup, the aerodynamics were modified to reflect
the different concepts. This is summarized by the above table.
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- Location of c.g. estimation B757-200 as an example Only some
major parts of the aircraft that significantly affect the c.g.
location are considered More parts will be added to our calculation
of c.g in the future. From Boeing.com 37
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- Calculation of c.g. 3 fuel tanks: forward(fuselage), aft and
wing tanks. c.g. shifting in flight Distance within forward and aft
c.g. limit for 10% of the mean aerodynamic chord. Take Off Gear up
Forward tank Aft tank Wing tank Gear down Fuel refilling CG
location Weigh t Wo Wland Forwar d c.g. limit Aft c.g. limit Stick
fixed neutral point SM nose Minimum allowable SM c.g. travel
diagram From Raymer 38
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- Static Margin *consider only wing and horizontal tail Static
margin positive for stability Use the lift curve slope of the wing
and the horizontal tail. Lift coefficient equation to find the
neutral point of the aircraft. Two categories, fixed parts (i.e.
wing, fuselage)and moveable parts(i.e. furnishing, payload) Target
static margin about 15%. Adjust the moveable parts to allow SM
reaches our desire value. Xcg from nose (ft) Xn from nose
(ft)Static Margin (%) 73.476.416.5 39
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- Tail sizing For jet transport aircraft: cht=1, cvt=0.09 Blended
Body Hybrid Asymmetric double fuselage V Tail Area (ft^2)810-
Horizontal Tail Area (ft^2) -487 Vertical Tail Area (ft^2) -325
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- Concept Summary 41 Hybrid Blended BodyAsymmetric Twin
Fuselage
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- Next Steps Carpet Plots Final Concept Decision Cost Estimate
Add details to Final Concept Sizing 42
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