Fall Semester 2009
Lab
4
Aerodynamic Estimation
4.1 Function of Aerodynamics in Design
4 2 Aerodynamic tool box introduction
4.2 Aerodynamic tool box introduction
4.3 Aerodynamics for Performance
Methodology
4.4 Aerodynamics for Stability and Control
Methodology
4 5 A d i f St t
4.5 Aerodynamics for Structures
Methodology
4.6 Assignment
Gary Coleman
AVD Laboratory
3 Initial Geometry, Weight and Balance
Geometry, Weight and Balance
Is typically derived duringthe configuration layout phase for the basic trades-studies on interest. The methods employed are typically statistical in nature and serve only as a start point for the design process
Covered In Lecture
Responsible Teams:
CAD and Synthesis (Chief Engineers)Derivation of initial Geometry Weight &
Balance Market Mission Definition Parametric Sizing Configuration Layout Balance Covered In Lecture Configuration Evaluation Flight Simulation Product Review
4 Aerodynamic Estimation for Performance
Configuration Trade-studies
Initial weight & balance and geometry
Configuration Evaluations Process
Aerodynamic estimation Propulsion estimation
Stability and control analysis
g g y
Structural analysis Performance analysis Internal systems analysis
Cost analysis
Convergence Check
Example: Compare initial and final values for weight Revised weight & balance estimation
Example: Compare initial and final values for weight
4.1 Function of Aerodynamics in Design
Aerodynamics:
Is the prediction and tailoring of theaerodynamic forces and moments required for predicting the aircrafts,
1. Performance
2. Stability and Control 3. Structural Loads
Performance:
R i th d l M i lift ffi i t f h
Requires the drag polar, Maximum lift coefficient for each mission segment and Lift curve
Stability and Control:
Requires static, dynamic and control derivatives
for critical flight conditions
Structure:
R
i
d
i
l
d di t ib ti
h
Requires aerodynamic load distribution over each
configuration component for the critical load cases
Pressure Distribution
4.3 Example: Citation X
Flight Conditions and Configuration settings:
For this example the Take-off flight condition will be examined. From the Mission Specification and Parametric sizing results the flight conditions and configuration settings are
flight conditions and configuration settings are.
Altitude: Sea-level
Velocity: 137 kts (231 ft/s)
Mach: 0.15
Re: 1.45x106
flap: 15.0
4.2 Aerodynamic tool box introduction
2-D aerodynamics:
Airfoil Drag Polar and Lift Curve:
1) Look for experimental data 1) Theory of Wing Sections 2) UIUC Ai f il D t Sit
2) UIUC Airfoil Data Site
(http://www.ae.uiuc.edu/m-selig/ads.html )
3) Paper DATCOM 4) Google!
2) Numerically Prediction
• Digital DATCOM – Method of singularities,
corrected for viscous and compressibility effects
• EPPLER – Potential flow solver
• X-FOIL– Potential flow solver corrected forX-FOIL– Potential flow solver, corrected for compressibility
• JavaFoil – Potential flow solver, corrected for compressibility
• TSFOIL – Transonic small disturbance theory Fl t C i l CFD ft ( t il bl
• Fluent – Commercial CFD software (not available in Capstone Lab)
4.2 Aerodynamic tool box introduction
3-D aerodynamics:
Drag Polar, Lift Curve, aerodynamic loads and stability and control derviatves:
1) Hand-book Methods
2) Digital DATCOM
4.2 Aerodynamic tool box introduction
Flight Conditions and Configuration settings for tool
box description:
For this example the Take-off flight condition will be examined. From the Mission Specification and Parametric sizing results the From the Mission Specification and Parametric sizing results the flight conditions and configuration settings are.
Altitude: Sea-level Velocity: 137 kts (231 ft/s) Mach: 0 15 Mach: 0.15 Re: 1.45x106 flap: 15.0
2-D Aerodynamics:
Citation X Wing Airfoil Approximation:
The Citation X’s wing is composed of supercritical airfoils which vary from root to tip. However, the actual airfoils are not availbile in the public domain and therefore the airfoils can be availbile in the public domain and therefore the airfoils can be approximated as follows -0.1 -0.05 0 0.05 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x/c y/c Upper Lower Mean camber line
GIII BL 145 GIII BL 45 9750 mm. Cessna 7500 -0.1 -0.05 0 0.05 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x/c y/c Upper Lower Mean camber line
GIII BL 45 F th f thi L b th ti i i i t d -0.1000 -0.0500 0.0000 0.0500 0.1000 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 x/c y/c Upper Lower Mean camber line
4900 mm.
For the purposes of this Lab the entire wing is approximated with the 10% t/c GIII BL 45 from the Gulfstream III. The airfoil ordinates can be found from the UIUC Airfoil Data Site
2-D Aerodynamics:
Citation X Empennage Airfoil Approximation:
The Citation X’s empennage also composed of supercritical airfoils with an approximate t/c of 10 % for the vertical and 8% for the horizontal.
For the purposes of this lab the NACA 64a010 and NACA 64-008a are used. The ordinates can be found from the UIUC Airfoil Data Site (http://www.ae.uiuc.edu/m-selig/ads.html )
0.1 Upper
Lower Mean camber line NACA 64a010 -0.1 -0.05 0 0.05 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x/c y/c
Mean camber line
NACA 64 008a 0 1 -0.05 0 0.05 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y/c Upper Lower Mean camber line NACA 64-008a
-0.1
2-D Aerodynamics:
Airfoil Drag Polar and Lift Curve:
1) Look for experimental data 1) Theory of Wing Sections 2) UIUC Ai f il D t Sit
2) UIUC Airfoil Data Site
(http://www.ae.uiuc.edu/m-selig/ads.html )
3) Paper DATCOM 4) Google!
2) Numerically Prediction
• Digital DATCOM – Method of singularities,
corrected for viscous and compressibility effects
• EPPLER – Potential flow solver
• X-FOIL– Potential flow solver corrected forX-FOIL– Potential flow solver, corrected for compressibility
• JavaFoil – Potential flow solver, corrected for compressibility
• TSFOIL – Transonic small disturbance theory Fl t C i l CFD ft ( t il bl
• Fluent – Commercial CFD software (not available in Capstone Lab)
2-D Aerodynamics: X-FOIL
X-FOIL is a menu based Airfoil analysis and design program developed by Mark Drela at MIT and is available for free
under a GNU General Public License.
Web site: http://web.mit.edu/drela/Public/web/xfoil/
Wing airfoil
1) Set-up airfoil coordinate file X-Foil\GIIIBL45 dat
1) Set-up airfoil coordinate file X-Foil\GIIIBL45.dat
Notes:
• first line is a the airfoil name
• Use only spaces between columns
C di t t t t th t ili d d
• Coordinates start at the trailing edge and run forward only the top surface and aft along the bottom surface
0.05
0.1 Upper
Lower
Mean camber line
-0.1 -0.05 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x/c y/c
2-D Aerodynamics: X-FOIL
2) Place the coordinate data file into the same folder as the X-FOIL executables. Double click xfoil.exe. You will see a directory and command listing.
3) T pe ‘LOAD GIIIBL45 dat’ 3) Type ‘LOAD GIIIBL45.dat’
2-D Aerodynamics: X-FOIL
4) Change to the Geometry design routine by typing 4) Change to the Geometry design routine by typing
‘GDES’ and hitting return. A plot visualizing the airfoil will appear
In this case X-FOIL gave a warning message that the airfoil has a poor coordinate distribution. To correct
thi th CADD d d t d th l l
this the CADD command was used to reduce the local panel angles.
5) Type ‘CADD’ in the GDES directory. This this case the function was used twice to reduce the maximum panel angle was around 3 deg.
6) Hit the ‘Enter’ to return to the XFOIL directory
7) Type ‘PCOP’ To re-panel the airfoil according to the 7) Type PCOP To re panel the airfoil according to the
2-D Aerodynamics: X-FOIL
8) Change to the Operation routine by typing ‘OPER’ from the X-FOIL directory. (Type ‘?’ to show the directory and command list again)
9) Turn on the Viscous mode and input the Reynolds and 9) Turn on the Viscous mode and input the Reynolds and
Mach number during take-off.
1) Type VISC and following the prompts 2) Type MACH and follow the prompts
10) T th t i t l ti f ti Thi ill 10) Turn on the auto point accumulation function. This will
produce an output file with the drag polar results. 1) Type ‘PACC’
1) Provide a name for the drag polar file 2) Provide a name for the output dump file 11) Specify range of angle of attack
2-D Aerodynamics: X-FOIL
12) Check the solution
1) Check for sharp spikes (mostly due to numerical instabilities!!)
2) 1st try increasing the viscous iteration limit with
2) 1 try increasing the viscous iteration limit with the ‘ITER’ command. If the problem presists try refining the number of panels and panel angles.
Note: Supercritical airfoils are typically difficult to model with panel methods!
2-D Aerodynamics: X-FOIL
13) Plot drag polar
1) Double click ‘pplot.exe’ in the X-Foil folder
2) Type ‘1’ the read the drag polar file and enter the name of the drag polar file created earlier. Hit return twice
return twice
3) Type ‘3’ to plot the drag polar
14) The drag polar data file can also be cop and pasted in 14) The drag polar data file can also be copy and pasted in
Excel for further formatting.
3-D Aerodynamics: Hand calculations
Before running any computer code it is important to have a Before running any computer code it is important to have a sanity check. The simplified handbook collected in methods
described in Approximate Drag Polar Method.doc can be
used for a quick approximation of the drag polar and maximum lift coefficient.
Notes
• These methods are approximate in nature and should only be used for parametric sizing purposes or for a sanity check
pu poses o o a sa ty c ec
• Most of these methods come from the USAF DATCOM, AIAA Aerospace designer engineers guide and Roskam Part I.
3-D Aerodynamics: Digital DATCOM
Digital DATCOM is Digital version of the USAF DATCOM Digital DATCOM is Digital version of the USAF DATCOM semi-empirical hand-book methods for aerodynamic
estimation. Digital DATCOM uses a simple text file input and output interface and has been a stable of aerodynamic
prediction in conceptual design sense the late 1970.
Digital DATCOM is an open source FORTRAN 77 program and is available in the public domain
See the AVD Digital DATCOM Quick Tour and Digital See t e g ta CO Qu c ou a d g ta
DATCOM users manual to get started
AVD Digital DATCOM Quick Tour.doc Digital DATCOM MANUAL.PDF
Notes Notes
• The airfoil sections data can be input from the X-Foil results or the airfoil coordinates can be input manually. In the later case Digital DATCOM uses a small disturbance method to predict the airfoil characteristics.
• Familiarize your self with the applicability of
Digital DATCOM. Sense the tool is based on semi-empirical methods it cannot be applied to all
3-D Aerodynamics: AVL Vortex Lattice Code
What is a vortex lattice code?
2-D case – approximating an airfoil as a flat plate at some angle of attack with a vortex filament, with strength , at the ¼ chord position and a control point at the ¾ chord position
pos t o a d a co t o po t at t e ¾ c o d pos t o (Weissinger’s approximation).
The lift (L’) and down wash (wi) and corresponding down wash velocity can be computed using the “Biot-Savart Law” (See McCormick(5) or Dreier(6) for more detail)
To produce a chord wise lift distribution simple add more vortex filaments and control points
filaments and control points
3-D Aerodynamics: AVL Vortex Lattice Code
What is a vortex lattice code?
3-D case – Expanding on the infinite flat plat assumption to a finite thin wing can be derived assuming two wing tip vortices extending from the wing quarter chord of each aft connected e te d g o t e g qua te c o d o eac a t co ected with a bounding vortex along the wing ¼ chord. Resulting in “Horse Shoe” vortex with strength .
Through summing the wash effects of each vortex at a central control point at mid span and ¾ chord the lift and induced drag control point at mid span and ¾ chord the lift and induced drag for this wing can be approximated for small angles of attack. Moving this lift vector to the ¼ chord produces the wing pitching moment.
3-D Aerodynamics: AVL Vortex Lattice Code
What is a vortex lattice code?
To produce a span wise lift distribution add more horse shoe vortices at the wing ¼ chord
To produce a chord wise and span wise distribution add horse shoe vortices at various chord locations
3-D Aerodynamics: AVL Vortex Lattice Code
How to operate AVL: AVL is a command driven (similar to x-foil)
which reads geometry and weight data from data files.
Getting Started: place “avl.exe” in the “runs” folder and follow
the. Double click avl.exe t e oub e c c a e e
The remainder of this introduction is a visualization of the “session1.txt” file which summarizes the basic commands to operate AVL
3-D Aerodynamics: AVL Vortex Lattice Code
To Load and visualize the aircraft geometry:
1) Load the geometry file “vanilla.avl” 2) Change to the “.OPER” directory
3-D Aerodynamics: AVL Vortex Lattice Code
To Load and visualize the aircraft geometry:
3) Type “G” to bring up a wire frame plot of the geometry 4) Type “K” to bring up keyboard commands for
3-D Aerodynamics: AVL Vortex Lattice Code
To Run AVL for a specified flight condition:
1) From the “OPER” directory type “M” to modify the flight conditions
2) Enter the first letter of the variable you wish to specify 1)) Example: “MN” for Mach number MNa p e o ac u be
3-D Aerodynamics: AVL Vortex Lattice Code
To Run AVL for a specified flight condition:
4) AVL does not appear to run angle of attack or mach number sweeps as done with DATCOM or Linair (If you find a way let me know!). There for you can specifically define the angle of attach, side-slip angle, etc., through de e t e a g e o attac , s de s p a g e, etc , t oug the constraint table which appears in when you are in the “OPER” directory
5) Set the angle of attack to 4.0 degrees by typing “A” to select angle of attack. Then Select the variable which AVL will use to set the angle of attack. Select angle of attach by entering “A” and finally enter the angle of y g y g attack 4.0 deg
Note: AOA can be constrained by any variable listed (Like CL)
3-D Aerodynamics: AVL Vortex Lattice Code
To Run AVL for a specified flight condition:
6) Type “x” to execute the vortex lattice code. The following screen will appear
6) Repeat the process for every flight condition or constraint
3-D Aerodynamics: AVL Vortex Lattice Code
To Visualize Output with AVL:
1) To Visualize the Lift distribution for all lifting surfaces type “T” for the Trefftx plane plot.
Wing Lift Distribution
Horizontal Tail Lift Distribution
3-D Aerodynamics: AVL Vortex Lattice Code
To Visualize Output with AVL:
1) To Visualize the pressure distribution for all lifting surfaces type “G” to return to the geometry plot 1)) Type “LO” to visualize the wing loading (pressure ype O to sua e t e g oad g (p essu e
distribution)
Wing Lift Distribution
Horizontal Tail Lift Distribution
3-D Aerodynamics: AVL Vortex Lattice Code
To Dump Output AVL to data files:
1) To output
1) Stability derivatives type “ST” or “SB” 2)) Total forcesota o ces “FT”
3) Surface forces “FN” (wing, horizontal tail, etc.)
4) Strip forces (lift distribution) “FS” 5) Element forces (control points) “FE” 6) Strip shear moments “VM” 6) Strip shear, moments VM
(drag and pitching moments)
7) Hinge moments “HM”
2) For each command it will prompt you to provide a file name to write the output.
Horizontal Tail Lift Distribution
3-D Aerodynamics: AVL Vortex Lattice Code
To Build an AVL model of the Citation X:
1) Start with the “bd2.avl” as a template for a wing, body horizontal and vertical tail configuration.
2)) Modify the reference areas mach number center of od y t e e e e ce a eas ac u be ce te o gravity references and CD0 (Vortex lattice methods only predict induced drag!!!!!!)
3) Modify the fuselage according the description in AVL’s Users guide (avl doc txt)
Users guide (avl_doc.txt)
Notes:
1) Fuselages and nacelles are modeled as
uncambered bodies of revolution with circular cross-sections. Therefore, for the Citation X use the Top view to determine the cross-sectional radius at each x-station.
2) Fuselage bodies are input in the same manner airfoils (i.e. specify radii from tail to nose across the top of the fuselage followed by the radii from p g y nose to tail along the bottom surface
4) For each lifting surface (wing, horizontal tail, vertical tail, etc. specify
5) For each command it will prompt you to provide a file name to write the output.
3-D Aerodynamics: AVL Vortex Lattice Code
To Build an AVL model of the Citation X:
4) For each lifting surface (wing, horizontal tail, vertical tail, etc.) any number of chordwise locations (root, tip, mid-span, etc.) specify Leading edge x, y, z location,
chord length, incidence angle and airfoil ordinate file
c o d e gt , c de ce a g e a d a o o d ate e according to the AVL users guide.
Notes:
1) The AVL can read the same airfoil data files as x-foil
2) You may use one or more airfoils for this model 2) You may use one or more airfoils for this model.
-0.1 -0.05 0 0.05 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x/c y/c Upper Lower Mean camber line
GIII BL 145 XLE3 yw -0.1 -0.05 0 0.05 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x/c y/c Upper Lower Mean camber line
GIII BL 45 YLE3 X -0.1000 -0.0500 0.0000 0.0500 0.1000 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 x/c y/c Upper Lower Mean camber line
Cessna 7500 Yw YLE2 XLE2 xw Xw zw
4.3 Aerodynamics for performance methodology
Performance Team Aerodynamic Requirements:
The performance team requires the aerodynamic drag polar and lift curve to predict range, take-off and landing field length, climb gradients, time to climb, service ceiling, etc.
etc.
Minimum Deliverables:
• Drag Polar for each mission segment
• Lift curve for each mission segment
Basic Procedure:
1. 2-D Airfoil selection/analysis (wind-tunnel data or X-FOIL)
2 3 D d b ild (H d b k DATCOM AVL) 2. 3-D drag build-up (Hand-book, DATCOM, AVL)
3. 3-D Lift curve with and without flaps (Hand-book, DATCOM, AVL)
Recommended References:
[1] Roskam, J, “Airplane Design, Part I: Preliminary Sizing of Airplanes,” DARcorporation, Lawrence, Kansas, 2004
[2] Roskam, J, “Airplane Design, Part VI: Preliminary Calculation of Aerodynamic, Thrust, and Power Characteristics,” DARcorporation, Lawrence, Kansas, 2004 [3] Hoak, D.E, Finck, R.D., “USAF Stability and Control DATCOM,” Flight Control
[3] Hoak, D.E, Finck, R.D., USAF Stability and Control DATCOM, Flight Control
Division Airforce Flight Dynamics Laboratory, Wright-Patterson Air Force Base, Ohio, 1978
[4] Hoerner, S.F,, “Fluid Dynamic Drag,” Midland Park, NJ, 1985 [5] Hoerner, S.F,, “Fluid-Dynamic Lift,” Midland Park, NJ, 1965
Performance Mission Segments:
The aerodynamics team must compute the trimmed lift and drag The aerodynamics team must compute the trimmed lift and drag for the primary mission segments with the appropriate
configuration settings Mission requirements Payload Weight (Kg) Payload Weight (Kg) Crew (2) 184 kg (410 lbs) Maximum Passengers (12) 1,110 kg (2,460 lbs) Design Passengers (6) 600 kg (1320 lbs) Range Design (0.82 M) 5,740 km (3,100 nm) High-Speed (0.92M) 4130 km (2,300 nm) Velocity
High-speed cruise (mid-weight) 0.92 M
Design Cruise Speed 0.82 M
Altitude (m)
Max operating 15,000 m (49,000 ft)
Design Cruise (0.82 M) 15,000 m (49,000 ft)
Max cruise speed (0.92 M, mid-weight) 11,300 m (37,000 ft)
Take-off field length (TOGW) 1 570 m (5 140 ft)
Take off field length (TOGW) 1,570 m (5,140 ft)
Landing field length (max landing weight) 1036 m (3,400 ft)
4.4 Aerodynamics for Stability and Control methodology
S&C Team Aerodynamic Requirements:
The S&C team must assess the stability and controllability of the aircraft and flight conditions which typically the most demining. These flight conditions are termed Design Constraining Flight Conditions (DCFC)
Constraining Flight Conditions (DCFC)
Minimum Deliverables:
• Static stability derivatives at each DCFC
• Dynamic stability derivatives at each DCFC Control derivatives at each DCFC
• Control derivatives at each DCFC
Basic Procedure:
1. Outline DCFC’s
2 C t t i d t ti t bilit d i ti (DATOM 2. Compute trimmed static stability derivatives (DATOM
/ AVL)
3. Compute dynamic stability derivatives (DATOM / AVL) 4. Compute control derivatives (DATOM / AVL)
5. Produce look-up tables/figures for each DCFC
Recommended References:
[1] Roskam, J, “Airplane Design, Part VI: Preliminary Calculation of Aerodynamic, Thrust, and Power Characteristics,” DARcorporation, Lawrence, Kansas, 2004 [2] Hoak, D.E, Finck, R.D., “USAF Stability and Control DATCOM,” Flight Control
Division Airforce Flight Dynamics Laboratory, Wright-Patterson Air Force Base, Ohio, 1978
[3] Etkin B., Reid, L.D., “Dynamics of Flight: Stability and Control,” 3rdEdition, John
Design Constraining Flight Conditions (DCFC):
In general the following table can be used to define the proper In general the following table can be used to define the proper DCFC’s for each control effector;
LoCE – Longitudinal Control Effector (Elevator)
DiCE – Directional Control Effector (Rudder)
LaCE – Lateral Control Effector (Aileron)( )
List of Classical DCFC’s
DCFC Description
LoCE LoCE
Trimmed Cruise Estimation of tim drag from the LoCE. High ‘g’
Maneuvering
LoCE's ability to perform pull-up/push-over maneuvers at maximum g loading.
Take-off Rotation LoCE's ability to lift the nose of the ground at rotation speed.
High Low speed LoCE's ability to maintain trim at forward c g during low-speed landing approach High , Low speed LoCE s ability to maintain trim at forward c.g. during low speed landing approach
with flaps-down, engines at idle, and high angle of attack. DiCE
Crosswind Landing DiCE's ability to maintain straight ground path during take-off and landing Anti-symmetric
Power
DiCE's ability to maintain straight flight path with most outboard engine inoperable
Crosswind Landing with OEI
Combination of Cross-wind landing and Anti-symmetric power
Adverse Yaw DiCE's ability to compensate for yawing moments produced by the aileron during rolls or high a, low speed, steep coordinated turns.
LaCE
Roll Performance LaCE's ability to bank the aircraft to a required bank angle in the required time Roll Performance LaCE s ability to bank the aircraft to a required bank angle in the required time.
Stability and Control Coefficients and Derivatives:
What does the S&C team need?
- trimmed Stability and control derivatives
Longitudinal Lateral/Directional Coefficients Static Derivatives 0 D C D C CL 0 L C Cm0 m C Cl Cn Cy trim D C CLtrimCmtrim Static Derivatives Dynamic Derivatives Control Derivatives D C CL Cm LoCE D C LoCE L C LoCE m C l C Cn Cy u L C CDu u m C q L C Cmq L C Cm Clp Cnp Cyp Clr Cnr Cyr LaCE l C LaCE n C LaCE y C DiCE l C DiCE n C DiCE y C
How to compute these parameters?
Handbook Component Build-up Methods (Etkin, USAF DATCOM, Digital DATCOM) Numerically Vortex Lattice Methods (AVL)
How to trim the configuration at each flight condition?
Roskam Part VII: Roskam Trim.pdf
Trim is defined as Lift = Weight Thrust = Drag Pitching moment = 0 V Lw Lt V V’ D t Mact lt
4.5 Aerodynamics Load Estimation
S&C Team Aerodynamic Requirements:
Structures team must determine the structural concept, layout and weight for the aircraft. To accomplish they require aerodynamic loads to estimate the forces and moment on the structure for critical load cases
moment on the structure for critical load cases
Minimum Deliverables:
• Distributed Aerodynamic Loads for the wing, fuselage and empennage for each critical load case (Pressure Distribution)
Distribution)
• Aerodynamic forces and moments (CL, CD, CM) for each load case
Basic Procedure:
1. Outline critical load cases
2. Compute disturbed Lift, Drag and Pitching Moment for each aircraft component
3. Produce look-up tables/figures for each critial load case
case
Recommended References:
[1] Niu, M., “Airframe Structural Design,” Technical Book Company, California, 1990
[2] H S F “Fl id D i Lift ” Midl d P k NJ 1965
[2] Hoerner, S.F,, “Fluid-Dynamic Lift,” Midland Park, NJ, 1965
[3] Roskam, J, “Roskam, J, “Airplane Design, Part VI: Preliminary Calculation of
Aerodynamic, Thrust, and Power Characteristics,” DARcorporation,
Lawrence, Kansas, 2004
Critical Load Cases for Transport Aircraft:
For each load condition the structures team requires the total aerodynamic forces and pressure distribution for……
Classical Critical Load Cases, Nui(1)
Load case Description
Pilot Induced Maneuvering and System malfunctions Combination stabilizer-elevator maneuvers
Longitudinal maneuvers which can load the LcCE and main wing.
Aileron and/or spoiler p Lateral maneuvers which apply an asymmetric loading condition on the maneuvers
pp y y g
wing.
Rudder maneuvers Directional maneuvers which the rudder applies loads to the vertical stabilizer and fuselage
Atmospheric Turbulence Power spectral approach and/or Discrete gust approach
Landing Landing gear and aerodynamic loads encountered during landing Ground handling
FAR ground handling Loads encountered during taxing maneuvers Rotational Taxing Loads encountered during taxing maneuvers Rotational ground maneuver Loads encountered take-off rotation
Jacking Loads jacking of aircraft for maintenance purposes Fail-safe and breakaway
4.6 Assignment
Assignment Aerodynamic for Performance:
• Produce a low speed 2-D drag polar and lift curve for the GIIIBL45 airfoil
• Produce the 3-D drag polar for T-O, Climb, Cruise, and Approach.
• Produce a Digital DATCOM model of the Citation and compile the long range cruise drag polar and Lift curve
The report should include,
1. Quick summary of the capability and limitations of X-FOIL and Digital DATCOM
2. 2-D drag polar from X-FOIL
3. The 3-D drag polar and lift curves from Digital DATCOM, AVL and hand-Calculations
• Plot 2-D and 3-D CL vs. CD, CL vs. AOA and L/D vs. CL
4.6 Assignment
Assignment Aerodynamic for Stability and Control:
• Construct a Digital DATCOM and AVL model of the Citation X
• Trim the aircraft for Cruise and Approach (with appropriate configuration settings).
• Report the resulting stability and control derivatives
The report should include,
1 Quick summary of the capability and limitations of AVL 1. Quick summary of the capability and limitations of AVL
and Digital DATCOM
2. Brief description of the trim method used
3. Table summarizing the stability and control derivatives during Cruise and Approach
4.6 Assignment
Assignment Structural Loads:
• Build an AVL Model Citation X
• Trim the aircraft during Cruise, and Approach by constraining the AOA to match the CL required.
• Produce the lift and pressure distribution for the lifting surfaces.
The report should include,
1. Quick summary of the capabilities and limitations of the vortex lattice code AVL
vortex lattice code AVL
2. 3-D wire-frame drawing of the Citation X model
3. AVL Lift distribution and pressure distribution plot for Cruise and Approach
Due: Update Report Friday 11-20-09 at 5:00 pm Final Report Friday 12-4-09 at 5:00 pm