Upload
jonolio
View
198
Download
0
Embed Size (px)
DESCRIPTION
Laboratory Manual
Citation preview
MAE 4350 – Aerospace Vehicle Design I
Fall Semester 2009
Lab 4 Aerodynamic Estimation
4.1 Function of Aerodynamics in Design4 2 Aerodynamic tool box introduction4.2 Aerodynamic tool box introduction4.3 Aerodynamics for Performance
Methodology4.4 Aerodynamics for Stability and Control
Methodology4 5 A d i f St t4.5 Aerodynamics for Structures
Methodology4.6 Assignment
Gary Coleman
AVD Laboratory
November 2009 © G. Coleman / UTA MAE / AVD LabPage 1
November 6, 2009
Mechanical and Aerospace Engineering Department (MAE)
3 Initial Geometry, Weight and Balance
Aerodynamic Estimation
Geometry, Weight and Balance Is typically derived duringthe configuration layout phase for the basic trades-studies oninterest. The methods employed are typically statistical innature 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
ConfigurationLayout
Balance
Covered In Lecture
Configuration Evaluation
Flight Simulation
ProductReview
Lab Section: Disciplinary Methods Introduction
November 2009 © G. Coleman / UTA MAE / AVD LabPage 2
4 Aerodynamic Estimation for Performance
Aerodynamic Estimation
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 CheckExample: Compare initial and final values for weight
Revised weight & balance estimation
Example: Compare initial and final values for weight
Present Trade-study results
November 2009 © G. Coleman / UTA MAE / AVD LabPage 3
4.1 Function of Aerodynamics in Design
Aerodynamic Estimation
Aerodynamics: Is the prediction and tailoring of theaerodynamic forces and moments required for predictingthe aircrafts,
1. Performance2. Stability and Control3. Structural Loads
Performance:
R i th d l M i lift ffi i t f hRequires the drag polar, Maximum lift coefficient for each mission segment and Lift curve
November 2009 © G. Coleman / UTA MAE / AVD LabPage 4
Stability and Control:
Aerodynamic Estimation
Requires static, dynamic and control derivatives for critical flight conditions
Configuration Derivatives
Ref: NASA CR-2144
November 2009 © G. Coleman / UTA MAE / AVD LabPage 5
Ref: NASA CR 2144
Structure:
R i d i l d di t ib ti h
Aerodynamic Estimation
Requires aerodynamic load distribution over eachconfiguration component for the critical load cases
Pressure Distribution
Ref: Howe, “Aircraft Loading and Structural Layout,” 2004
November 2009 © G. Coleman / UTA MAE / AVD LabPage 6
4.3 Example: Citation X
Aerodynamic Estimation
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 areflight conditions and configuration settings are.
Altitude: Sea-levelVelocity: 137 kts (231 ft/s)Mach: 0.15Re: 1.45x106
flap: 15.0Landing Gear: Down
November 2009 © G. Coleman / UTA MAE / AVD LabPage 7
4.2 Aerodynamic tool box introduction
Aerodynamic Estimation
2-D aerodynamics:Airfoil Drag Polar and Lift Curve:
1) Look for experimental data1) Theory of Wing Sections2) UIUC Ai f il D t Sit2) UIUC Airfoil Data Site
(http://www.ae.uiuc.edu/m-selig/ads.html )3) Paper DATCOM4) 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)
November 2009 © G. Coleman / UTA MAE / AVD LabPage 8
4.2 Aerodynamic tool box introduction
Aerodynamic Estimation
3-D aerodynamics:Drag Polar, Lift Curve, aerodynamic loads and stability and
control derviatves:1) Hand-book Methods
2) Digital DATCOM
1) AVL Vortex Lattice Code
November 2009 © G. Coleman / UTA MAE / AVD LabPage 9
4.2 Aerodynamic tool box introduction
Aerodynamic Estimation
Flight Conditions and Configuration settings for toolbox description:
For this example the Take-off flight condition will be examined. From the Mission Specification and Parametric sizing results theFrom the Mission Specification and Parametric sizing results the flight conditions and configuration settings are.
Altitude: Sea-levelVelocity: 137 kts (231 ft/s)Mach: 0 15Mach: 0.15Re: 1.45x106
flap: 15.0Landing Gear: Down
November 2009 © G. Coleman / UTA MAE / AVD LabPage 10
2-D Aerodynamics:
Aerodynamic Estimation
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 beavailbile 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 (http://www.ae.uiuc.edu/m-selig/ads.html )
November 2009 © G. Coleman / UTA MAE / AVD LabPage 11
2-D Aerodynamics:
Aerodynamic Estimation
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 )
0.1Upper
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
x/c
November 2009 © G. Coleman / UTA MAE / AVD LabPage 12
2-D Aerodynamics:
Aerodynamic Estimation
Airfoil Drag Polar and Lift Curve:1) Look for experimental data
1) Theory of Wing Sections2) UIUC Ai f il D t Sit2) UIUC Airfoil Data Site
(http://www.ae.uiuc.edu/m-selig/ads.html )3) Paper DATCOM4) 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)
These will be used for the Capstone Lab
November 2009 © G. Coleman / UTA MAE / AVD LabPage 13
2-D Aerodynamics: X-FOIL
Aerodynamic Estimation
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 dat1) 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
0.1Upper
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
November 2009 © G. Coleman / UTA MAE / AVD LabPage 14
2-D Aerodynamics: X-FOIL
Aerodynamic Estimation
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’
November 2009 © G. Coleman / UTA MAE / AVD LabPage 15
2-D Aerodynamics: X-FOIL4) Change to the Geometry design routine by typing
Aerodynamic Estimation
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 lthis 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
November 2009 © G. Coleman / UTA MAE / AVD LabPage 16
7) Type PCOP To re panel the airfoil according to the new coordinate points. This refinement will increase the accuracy of the final pressure distribution and drag polar
2-D Aerodynamics: X-FOIL
Aerodynamic Estimation
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 and9) Turn on the Viscous mode and input the Reynolds and Mach number during take-off.1) Type VISC and following the prompts2) Type MACH and follow the prompts
10) T th t i t l ti f ti Thi ill10) 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 file2) Provide a name for the output dump file
11) Specify range of angle of attack1) Type ‘ASEQ’ and follow the prompts.
November 2009 © G. Coleman / UTA MAE / AVD LabPage 17
2-D Aerodynamics: X-FOIL
Aerodynamic Estimation
12) Check the solution1) Check for sharp spikes (mostly due to numerical
instabilities!!)
2) 1st try increasing the viscous iteration limit with2) 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!to model with panel methods!
November 2009 © G. Coleman / UTA MAE / AVD LabPage 18
2-D Aerodynamics: X-FOIL
Aerodynamic Estimation
13) Plot drag polar1) Double click ‘pplot.exe’ in the X-Foil folder2) Type ‘1’ the read the drag polar file and enter the
name of the drag polar file created earlier. Hit return twicereturn twice
3) Type ‘3’ to plot the drag polar
14) The drag polar data file can also be cop and pasted in14) The drag polar data file can also be copy and pasted in Excel for further formatting.
15) Repeat for the empennage airfoils
November 2009 © G. Coleman / UTA MAE / AVD LabPage 19
3-D Aerodynamics: Hand calculationsBefore running any computer code it is important to have a
Aerodynamic Estimation
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 checkpu 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.
November 2009 © G. Coleman / UTA MAE / AVD LabPage 20
3-D Aerodynamics: Digital DATCOMDigital DATCOM is Digital version of the USAF DATCOM
Aerodynamic Estimation
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 taDATCOM users manual to get started
AVD Digital DATCOM Quick Tour.docDigital DATCOM MANUAL.PDF
NotesNotes• 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 configurations.g
November 2009 © G. Coleman / UTA MAE / AVD LabPage 21
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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 pointsfilaments and control points
[5] McCormick, B.W., “Aerodynamics, Aeronautics and Flight Mechanics,” Wiley, NewYork, 1979
November 2009 © G. Coleman / UTA MAE / AVD LabPage 22
York, 1979
[6] Dreier, M.E., “Introduction to Helicopter and Tiltrotor Flight Simulation,” AIAAEducational Series, American Institute of Aeronautics and Astronautics.,Reston, VA., 2007
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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 ectedwith 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 dragcontrol 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.
November 2009 © G. Coleman / UTA MAE / AVD LabPage 23
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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
November 2009 © G. Coleman / UTA MAE / AVD LabPage 24
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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 AVLoperate AVL.
November 2009 © G. Coleman / UTA MAE / AVD LabPage 25
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
To Load and visualize the aircraft geometry:1) Load the geometry file “vanilla.avl”2) Change to the “.OPER” directory
November 2009 © G. Coleman / UTA MAE / AVD LabPage 26
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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
manipulating the plot
November 2009 © G. Coleman / UTA MAE / AVD LabPage 27
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
To Run AVL for a specified flight condition:1) From the “OPER” directory type “M” to modify the
flight conditions2) Enter the first letter of the variable you wish to specify
1) Example: “MN” for Mach number MN) a p e o ac u be
November 2009 © G. Coleman / UTA MAE / AVD LabPage 28
3) Repeat for velocity, density, Mass, gravitational constant, and center of gravity (minimum).
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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 ougthe 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 gattack 4.0 deg
Note: AOA can be constrained by any variable listed (Like CL)
November 2009 © G. Coleman / UTA MAE / AVD LabPage 29
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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
November 2009 © G. Coleman / UTA MAE / AVD LabPage 30
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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
Downwash angle distribution
November 2009 © G. Coleman / UTA MAE / AVD LabPage 31
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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 edistribution)
Wing Lift Distribution
Horizontal Tail Lift Distribution
Downwash angle distribution
November 2009 © G. Coleman / UTA MAE / AVD LabPage 32
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
To Dump Output AVL to data files: 1) To output
1) Stability derivatives type “ST” or “SB”2) Total forces “FT”) ota o ces3) 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
Downwash angle distribution
November 2009 © G. Coleman / UTA MAE / AVD LabPage 33
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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 ogravity 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 ynose 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.
November 2009 © G. Coleman / UTA MAE / AVD LabPage 34
3-D Aerodynamics: AVL Vortex Lattice Code
Aerodynamic Estimation
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 eaccording to the AVL users guide.
Notes:1) The AVL can read the same airfoil data files as x-
foil2) You may use one or more airfoils for this model2) 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
i3
November 2009 © G. Coleman / UTA MAE / AVD LabPage 35
Zw
iwxw
i3
ZLE3
4.3 Aerodynamics for performance methodology
Aerodynamic Estimation
Performance Team Aerodynamic Requirements:The performance team requires the aerodynamic dragpolar and lift curve to predict range, take-off and landingfield 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 ControlDivision Airforce Flight Dynamics Laboratory, Wright-Patterson Air ForceBase, Ohio, 1978
[4] Hoerner, S.F,, “Fluid Dynamic Drag,” Midland Park, NJ, 1985
[5] Hoerner, S.F,, “Fluid-Dynamic Lift,” Midland Park, NJ, 1965
November 2009 © G. Coleman / UTA MAE / AVD LabPage 36
Performance Mission Segments:
The aerodynamics team must compute the trimmed lift and drag
Aerodynamic Estimation
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)
Fuel reserves 45 min at 1,524 km (5,000 ft)
November 2009 © G. Coleman / UTA MAE / AVD LabPage 37
4.4 Aerodynamics for Stability and Control methodology
Aerodynamic Estimation
S&C Team Aerodynamic Requirements:The S&C team must assess the stability and controllabilityof the aircraft and flight conditions which typically themost demining. These flight conditions are termed DesignConstraining 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’s2 C t t i d t ti t bilit d i ti (DATOM2. 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 ControlDivision Airforce Flight Dynamics Laboratory, Wright-Patterson Air ForceBase, Ohio, 1978
[3] Etkin B., Reid, L.D., “Dynamics of Flight: Stability and Control,” 3rd Edition, JohnWiley and Sons, Inc, New York, 1996
[3] Torenbeek E “Synthesis of Subsonic Airplane Design ” Delft University Press
November 2009 © G. Coleman / UTA MAE / AVD LabPage 38
[3] Torenbeek, E., “Synthesis of Subsonic Airplane Design,” Delft University Press,London, 1996
Design Constraining Flight Conditions (DCFC):
In general the following table can be used to define the proper
Aerodynamic Estimation
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’sDCFC Description
LoCELoCE
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 approachHigh , 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 timeRoll Performance LaCE s ability to bank the aircraft to a required bank angle in the required time.
November 2009 © G. Coleman / UTA MAE / AVD LabPage 39
Stability and Control Coefficients and Derivatives:
Aerodynamic Estimation
What does the S&C team need?- trimmed Stability and control derivatives
Longitudinal Lateral/Directional
Coefficients
Static Derivatives
0DC
DC LC
0LC0mC
mClC nC yC
trimDCtrimLC
trimmC
Static Derivatives
Dynamic Derivatives
Control Derivatives
DC LC mC
LoCEDC LoCELC LoCEmC
lC nC yC
uLCuDC
umCqLC qmC
LC mC plC
pnC pyCrl
C rnCryC
LaCElC LaCEnC LaCEyC
DiCElC DiCEnC DiCEyC
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 asLift = Weight
Thrust = DragPitching moment = 0
V
Lw
Lt
V
V’
D
Dt
M
Mact
lt
November 2009 © G. Coleman / UTA MAE / AVD LabPage 40
DwMacw
4.5 Aerodynamics Load Estimation
Aerodynamic Estimation
S&C Team Aerodynamic Requirements:Structures team must determine the structural concept,layout and weight for the aircraft. To accomplish theyrequire aerodynamic loads to estimate the forces andmoment on the structure for critical load casesmoment on the structure for critical load cases
Minimum Deliverables:
• Distributed Aerodynamic Loads for the wing, fuselageand empennage for each critical load case (PressureDistribution)Distribution)
• Aerodynamic forces and moments (CL, CD, CM) foreach load case
Basic Procedure:
1. Outline critical load cases2. Compute disturbed Lift, Drag and Pitching Moment
for each aircraft component3. Produce look-up tables/figures for each critial load
casecase
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 ofAerodynamic, Thrust, and Power Characteristics,” DARcorporation,Lawrence, Kansas, 2004
[4] Howe, D., “Aircraft Loading and Structural Layout,” AIAA Educational Series,Virgina, 2004
November 2009 © G. Coleman / UTA MAE / AVD LabPage 41
g ,
[5] Lomax, T., “Structural Loads Analysis for Commercial Transport Aircraft: Theroyand Practice,” AIAA Educational Series, Virgina, 1995
Critical Load Cases for Transport Aircraft:
Aerodynamic Estimation
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 Lateral maneuvers which apply an asymmetric loading condition on the pmaneuvers
pp y y gwing.
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 design
November 2009 © G. Coleman / UTA MAE / AVD LabPage 42
4.6 Assignment
Aerodynamic Estimation
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-FOIL3. 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
• Tabulate L/Dmax and CL and CD and L/Dmax
November 2009 © G. Coleman / UTA MAE / AVD LabPage 43
4.6 Assignment
Aerodynamic Estimation
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 AVL1. Quick summary of the capability and limitations of AVL and Digital DATCOM
2. Brief description of the trim method used3. Table summarizing the stability and control derivatives
during Cruise and Approach 4. Comparison of Digital DATCOM and AVL results
November 2009 © G. Coleman / UTA MAE / AVD LabPage 44
4.6 Assignment
Aerodynamic Estimation
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 AVLvortex lattice code AVL
2. 3-D wire-frame drawing of the Citation X model3. 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
November 2009 © G. Coleman / UTA MAE / AVD LabPage 45