AE 1350
Lecture #2
TOPICS ALREADY COVERED
• We reviewed the history of aeronautics and
rocketry.
• We discussed the parts of the airplane.
• We discussed various ways an aircraft is
graphically represented.
VARIOUS DISCIPLINES
Structures
Propulsion
Stability &
Control
Design
Aerodynamics &
Performance
Axes of an Airplane
Roll of an Airplane
• The longitudinal axis
extends lengthwise through
the fuselage from the nose
to the tail.
• Movement of the airplane
around the longitudinal axis
is known as roll and is
controlled by movement of
the ailerons.
Yaw
• The vertical or normal
axis passes vertically
through the center of
gravity.
• Movement of the
airplane around the
vertical axis is yaw.
• Yaw is controlled by
movement of the rudder.
PITCH
• The lateral axis extends
crosswise from wingtip to
wing tip.
• Movement of the airplane
around the lateral axis is
known as pitch.
• Pitch is controlled by
movement of the
elevators.
AERODYNAMIC CONTROL SURFACES
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Elevators control pitch angle
Ailerons control roll angle
Rudder controls yaw angle
Flaps increase lift and drag
Leading edge slats increase lift
Drag brakes increase drag
Spoilers reduce lift.
Canard is a horizontal control surface placed near
the nose.
TOPICS TO BE COVERED
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Roadmap of Disciplines
“English” to “S.I.” units
Common Aerospace Terminology
Preliminary Thoughts on Aerospace Design
Specifications (“Specs”) and Standards
System Integration
AEROSPACE ENGINEERING
DISCIPLINES
• Design, modeling, and testing aerospace vehicles
requires knowledge and training in the areas of
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Aerodynamics
Structures
Flight Mechanics, Stability & Control
Propulsion
Performance
Design - An integration of these disciplines
to come up with a new product or concept
ENGLISH UNITS
• U. S. aerospace industries use this convention.
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mass : lbm or in slugs
Distance : feet
Time: seconds
Force: lbf (pronounced pound force)
Pressure: psi (pounds per square inch), or in atm
energy: Btu (British thermal units)
Power: HP
Temperature: Fahrenheit or degree Rankine ( R)
S. I. UNITS
Système International d’Unites
• Most other European and Asian nations use this.
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mass - kg
Distance - m (pronounced meters)
Time - seconds
Force - N (pronounced Newtons)
Pressure - N/m2, or in atm
energy in Joules
Power in Watts (Joule/sec)
Temperature in Celsius or degree Kelvin ( K)
English Units (Continued)
• Note:
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1 slug = 32.2 lbm
1 atm = 14.7 psi (14.7 pounds per square inch)
0 Degrees F = 460 Degrees Rankine
We convert Fahrenheit to Rankine by adding
460 to F
– 1 BTU = 778.15760 ft lb
– 1 HP = 550 ft.lb/s
CONVERSION FACTORS
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1 ft = 0.3048 m
1 slug = 14.594 kg
1 slug = 32.2 lbm
1 lbm = 0.4536 kg
1 lb = 4.448 N
1 atm = 114.7 psi = 2116 lb/ft2 = 1.01 x 105 N/m2
1degree K = 1.8 degree R
Convert Celsius to Kelvin by adding 273 to Celsius
1HP = 745.69987 Watts
g = Acceleration due to gravity = 32.2 ft/s2 = 9.8 m/s2
Examples
• Wright Flyer weighed 340 kg
– Its weight in English Units:
 1 slug   32.2lbm 
  
  750lbm
340kg  
 14.594 kg   1 slug 
• Its wing area was 46.5 m2
– The area in English units:
2
1 ft 
2 
2
46.5m  

500
ft

 0.3048m 
– Its speed = 56 km/h = 35mph (VFY: verify for
yourself, please!)
AEROSPACE TERMINOLOGY
• GW=Gross Weight= The nominal weight for a standard
mission before the aircraft (or spacecraft) takes off.
• Crew Weight: Weight of crew and associated equipment
(parachute, oxygen, etc.)
• P/L= Payload Weight = Weight the aircraft was designed to
carry. (passengers weight, baggage for aircraft;satellites,
imaging equipment etc. for spacecraft)
• Fuel/Weight: That required to do the mission plus required
reserves
• Empty Weight = What the aircraft or spacecraft weighs
when it is nominally empty (may include trapped fuel )
• GW = Crew weight+ P/L + Fuel Weight + Empty Weight
AEROSPACE TERMINOLOGY
– Wing Loading = Aircraft Weight/Wing Area
 lb N 
 2 , 2 
 ft m 
N 
 lb
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– Power Loading = Aircraft Weight/ Nominal Engine Power HP Watt 
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– Aspect ratio, AR = (Wing Span)2 / Wing Area
– Taper ratio = Root Chord/ Tip Chord
– Specific Fuel Consumption, sfc = (Fuel Weight)/ (Power x Hour)
– Empty Weight Fraction = Empty Weight/ Gross Weight
– Payload Fraction = Payload Weight/ Gross Weight
TYPICAL WING LOADING
• Light Civil Aircraft: 10 to 30 lb/ft2
• High Altitude Fighter 30 to 60 lb/ft2
• Interceptor Fighter 120 to 350 lb/ft2
• Long Range Transport 110 to 140 lb/ft2
PRELIMINARY THOUGHTS ON DESIGN
• Design is, in general,
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a team effort
a large system integration activity
done in three stages
iterative
creative, knowledge based.
• The three stages are:
– Conceptual design
– Preliminary design
– Detailed design
Conceptual Design
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What will it do?
How will it do it?
What is the general arrangement of parts?
The end result of conceptual design is an
artist’s or engineer’s conception of the
vehicle/product.
• Example: Clay model of an automobile.
Conceptual Designs
Dan Raymer sketch
Conceptual Designs
1988 Lockheed Design
Preliminary Design
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How big will it be?
How much will it weigh?
What engines will it use?
How much fuel or propellent will it use?
How much will it cost?
This is what you will do in this course.
Preliminary Design Analysis
Wing sizing spreadsheet
Written by Neal Willford 12/29/03 for Sport Aviation
Based on methods presented in "Technical Aerodynamics" by K.D. Wood, "Engineering Aerodynamics" by W.S. Diehl, and "Airplane Performance, Stability and Control" by Perkins and Hage
This spreadsheet is for educational purposes only and may contain errors. Any attempt to use the results for actual design purposes are done at the user's own risk.
Input required in yellow cells
Wing area sizing
A/C weight:
Desired stall speed:
Desired stall speed:
1150 lbs
Flaps up Clmax:
45 knots, flaps up
Flaps down Clmax:
39 knots, flaps down
1.42 get from Airplane CL page
1.78 get from Airplane CL page
Minimum wing area needed to meet the flaps up and flaps down stall speed requirements. Use the larger of the two areas
Min. Wing Area =
125.3 sq ft, to meet desired flaps down stall speed
Min. Wing Area =
118.0 sq ft, to meet desired flaps up stall speed
Wing span sizing. Choose span to obtain desired rate of climb and ceiling
Flat plate area:
4.00 sq ft
Total wing area:
122.4 sq ft
Wingspan:
35.5 ft (upper wingspan for a biplane or wingspan for a monoplane)
estimated k1 =
1.00 biplane span factor
Lower wingspan:
0 ft (lower wingspan for a biplane. Enter 0 for a monoplane)
Wing gap:
0 ft (distance between upper and lower wing if the a/c is a biplane. Enter 0 for a monoplane)
max fus width:
3.5 feet
est airplane 'e'=
0.72 Oswald factor
Max horsepower:
79 bhp
Max prop RPM:
2422.907489
Prop W.R.:
0.066 chord/Diameter @ 75% prop radius
Peak Efficiency 2 Blade Prop Dia. =
66 inches
Peak Efficiency Pitch =
63 inches
Propeller Diameter:
63 inches
mu =
0.03 .03 concrete, .05 short grass, 0.1 long grass
Est Prop efficiency=
0.75
Vto/Vstall
1.15 ratio of takeoff speed to stall speed (1.15 to 1.2)
Prop efficiency:
0.75 ** iterate until equals estimated prop efficiency (then subtract .03 if using a wooden propeller)
Estimated sea level standard day performance
Vmax =
127 mph =
V best ROC =
72 mph =
Vmax L/D =
65 mph =
V min pwr =
49 mph =
Vstall, clean =
50.9 mph =
Vstall, flaps =
45.4 mph =
Wing loading=
9.4 lbs/sq ft
Power loading =
14.6 lbs/horsepower
Estimated takeoff and landing performance
Fixed Pitch Prop
T.O. distance =
609 feet
T.O. over 50' =
929 feet
Landing distance ground roll =
Landing over 50' obstacle =
110
63
56
43
44.2
39.4
knots
knots
knots
knots
knots
knots
Fixed Pitch Propeller Performance
max ROC =
902 fpm
Abs. Ceiling =
20557 feet
Service Ceiling=
18277 feet
Constant Speed Propeller Performance
max ROC =
1133 fpm
Abs. Ceiling =
22899 feet
Service Ceiling=
20878 feet
Background calculations
Cdo =
Lp =
Lt =
Ls =
lambda =
Wing AR =
Lt cnsspd =
lamda cnsspd=
Cs 3bl =
L/Dmax =
Prop/body int=
Propeller advance ratio, J =
T (fixed pitch)=
Tc (fixed pitch)=
T (constant speed)=
Tc (constant speed)=
R =
Dc =
Xt fixed pitch=
Ht fixed pitch=
Xt constant speed=
Ht constant speed=
T.O. Speed=
Constant Speed Prop
T.O. distance =
414 feet
T.O. over 50' =
686 feet
420 feet, flaps down (1.15xVstall)
1023 feet, flaps down (1.15xVstall)
Estimated power off sink rate (based on method in the March 1990 issue of Sport Aviation)
windmilling e:
0.48 APPROXIMATELY 2/3 of power on 'e'
min sink speed =
47 knots =
54 mph
sink rate =
506 ft/min
www.aero-siam.com/S405-WingDesign.xls
Detailed Design
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How many parts will it have?
What shape will they be?
What materials?
How will it be made?
How will the parts be joined?
How will technology advancements (e.g.
lightweight material, advanced airfoils,
improved engines, etc.) impact the design?
Detailed Design
Dassault Systems - CATIA
Detailed Design
Dassault Systems - CATIA
Detailed Design
Dassault Systems - CATIA
A380 Arrangement
SPECIFICATION AND
STANDARDS
• The designer needs to satisfy
– Customer who will buy and operate the vehicle
(e.g. Delta, TWA)
– Government Regulators (U.S. , Military,
European, Japanese…)
CUSTOMER SPECIFICATIONS
• Performance:
– Payload weight and volume
– how far and how fast it is to be carried
– how long and at what altitude
– passenger comfort
– flight instruments, ground and flight handling qualities
• Cost
• Prince of system and spares, useful life,
maintenance hours per flight hour
• Firm order of units, options, Delivery schedule, payment
schedule
TYPICAL GOVERNMENT STANDARDS
• Civil
– FAA Civil Aviation Regulations define such things as
required strength, acoustics, effluents, reliability, takeoff and landing performance, emergency egress time.
• Military
– May play a dual role as customer and regulator
– MIL SPECS (Military specifications)
– May set minimum standards for Mission turn-around
time, strength, stability, speed-altitude-maneuver
capability, detectability, vulnerability
SYSTEM INTEGRATION
• Aircraft/Spacecraft Design often involves
integrating parts, large and small, made by other
vendors, into an airframe or spaceframe (also
called “the bus.”)
• Parts include
– engines, landing gear, shock absorbers, wheels, brakes,
tires
– avionics (radios, antennae, flight control computers)
– cockpit instruments, actuators that move control
surfaces, retract landing gears, etc...
A380 Production
AEROSPACE DESIGN
INVOLVES
• Lot of Analyses
• Ground testing and simulation (e.g. wind
tunnel tests of model aircraft, flight
simulation, drop tests, full scale mock-up,
fatigue tests)
• Flight tests