MAE 4350 - Lab 4 Aerodynamics

MAE 4350 – Aerospace Vehicle Design I Fall Semester 2009

Lab

4

Aerodynamic Estimation

4.1 42 4.2 4.3

Function of Aerodynamics in Design Aerodynamic tool box introduction Aerodynamics for Performance Methodology Aerodynamics for Stability and Control Methodology A Aerodynamics d i for f Structures St t Methodology Assignment

4.4 45 4.5 4.6

Gary Coleman AVD Laboratory November 6, 2009

Mechanical and Aerospace Engineering Department (MAE) November 2009 Page 1

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Aerodynamic Estimation

3 Initial Geometry, Weight and Balance Geometry, Weight and Balance Is typically derived during the 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

Responsible Teams: CAD and Synthesis (Chief Engineers) Derivation of initial Geometry Weight & Balance Configuration Layout

Covered In Lecture Mission Definition

Parametric Sizing

Market

Lab Section: Disciplinary Methods Introduction Configuration Evaluation

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Flight Simulation

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Covered In Lecture Product Review

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Aerodynamic Estimation

4 Aerodynamic Estimation for Performance Configuration Evaluations Process Configuration Trade-studies Initial weight g & balance and g geometry y Aerodynamic estimation Propulsion estimation Stability and control analysis Structural analysis Performance analysis Internal systems analysis Revised weight & balance estimation Cost analysis Convergence Check Example: Compare initial and final values for weight Present Trade-study results

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Aerodynamic Estimation

4.1 Function of Aerodynamics in Design Aerodynamics: Is the prediction and tailoring of the aerodynamic forces and moments required for predicting the aircrafts, 1. 2. 3.

Performance Stability and Control Structural Loads

Performance: Requires R i the th drag d polar, l Maximum M i lift coefficient ffi i t for f each h mission segment and Lift curve

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Aerodynamic Estimation

Stability and Control: Requires static, dynamic and control derivatives for critical flight conditions

Configuration Derivatives

Ref: NASA CR CR-2144 2144

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Aerodynamic Estimation

Structure: Requires R i aerodynamic d i load l d distribution di t ib ti over each h configuration component for the critical load cases

Pressure Distribution

Ref: Howe, “Aircraft Loading and Structural Layout,” 2004

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Aerodynamic Estimation

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. are Altitude: Velocity: Mach: Re:

Sea-level 137 kts (231 ft/s) 0.15 1.45x106

flap:

15.0 Down

Landing Gear:

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Aerodynamic Estimation

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 Airfoil f il D Data t Sit Site (http://www.ae.uiuc.edu/m-selig/ads.html ) 3) Paper DATCOM 4) Google! 2)

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Numerically Prediction • Digital DATCOM – Method of singularities, corrected for viscous and compressibility effects • EPPLER – Potential flow solver • X-FOIL– Potential flow solver solver, corrected for compressibility • JavaFoil – Potential flow solver, corrected for compressibility • TSFOIL – Transonic small disturbance theory • Fl Fluent t – Commercial C i l CFD software ft ((nott available il bl in Capstone Lab)

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Aerodynamic Estimation

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

1)

AVL Vortex Lattice Code

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Aerodynamic Estimation

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 flight conditions and configuration settings are. Altitude: Velocity: Mach: Re:

Sea-level 137 kts (231 ft/s) 0 15 0.15 1.45x106

flap:

15.0 Down

Landing Gear:

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Aerodynamic Estimation

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 approximated as follows GIII BL 145 Upper

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GIII BL 45

9750 mm.

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Cessna 7500 Upper

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4900 mm.

For the F th purposes off this thi Lab L b the th entire ti wing i is i approximated i t d 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 )

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Aerodynamic Estimation

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 )

NACA 64a010 Upper

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NACA 64 64-008a 008a Upper

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Aerodynamic Estimation

2-D Aerodynamics: Airfoil Drag Polar and Lift Curve: 1) Look for experimental data 1) Theory of Wing Sections 2) UIUC Ai Airfoil f il D Data t Sit 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 solver, corrected for compressibility • JavaFoil – Potential flow solver, corrected for compressibility • TSFOIL – Transonic small disturbance theory • Fl Fluent t – Commercial C i l CFD software ft ((nott available il bl in Capstone Lab) These will be used for the Capstone Lab

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Aerodynamic Estimation

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 X-Foil\GIIIBL45 dat Notes: • first line is a the airfoil name • Use only spaces between columns • C Coordinates di t start t t att the th trailing t ili edge d and d run forward only the top surface and aft along the bottom surface

Upper

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Aerodynamic Estimation

2-D Aerodynamics: X-FOIL 2)

3)

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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. T pe ‘LOAD GIIIBL45 Type GIIIBL45.dat’ dat’

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Aerodynamic Estimation

2-D Aerodynamics: X-FOIL 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 the this th CADD command d was used d to t reduce d the th local l l 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’ PCOP To re re-panel panel the airfoil according to the new coordinate points. This refinement will increase the accuracy of the final pressure distribution and drag polar

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Aerodynamic Estimation

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 Mach number during take-off. 1) Type VISC and following the prompts 2) Type MACH and follow the prompts

10) T Turn on the th auto t point i t accumulation l ti ffunction. ti Thi This will ill 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 1) Type ‘ASEQ’ and follow the prompts.

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Aerodynamic Estimation

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 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!

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Aerodynamic Estimation

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 3) Type ‘3’ to plot the drag polar

14) The drag polar data file can also be cop copy and pasted in Excel for further formatting. 15) Repeat for the empennage airfoils

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Aerodynamic Estimation

3-D Aerodynamics: Hand calculations 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 •

•

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These methods are approximate in nature and should only be used for parametric sizing purposes pu poses o or for o a sa sanity ty c check ec Most of these methods come from the USAF DATCOM, AIAA Aerospace designer engineers guide and Roskam Part I.

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Aerodynamic Estimation

3-D Aerodynamics: Digital 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 t e AVD Digital g ta DATCOM CO Quick Qu c Tour ou and a d Digital g ta DATCOM users manual to get started AVD Digital DATCOM Quick Tour.doc Digital DATCOM MANUAL.PDF Notes •

•

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The airfoil sections data can be input from the XFoil 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 semiempirical methods it cannot be applied to all configurations. g

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Aerodynamic Estimation

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 pos to a and d a co control t o po pointt at the t e ¾ chord c o d position 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

[5] McCormick, B.W., “Aerodynamics, Aeronautics and Flight Mechanics,” Wiley, New York, 1979 [6]

Dreier, M.E., “Introduction to Helicopter and Tiltrotor Flight Simulation,” AIAA Educational Series, American Institute of Aeronautics and Astronautics., Reston, VA., 2007

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Aerodynamic Estimation

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 e te d g from o the t e wing g quarter qua te c chord o do of eac each a aftt co connected 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 for this wing can be approximated for small angles of attack. Moving this lift vector to the ¼ chord produces the wing pitching moment.

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Aerodynamic Estimation

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

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Aerodynamic Estimation

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 tthe. e Double oub e click c c a avl.exe e e

The remainder of this introduction is a visualization of the “session1.txt” file which summarizes the basic commands to operate AVL. AVL

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Aerodynamic Estimation

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

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Aerodynamic Estimation

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 manipulating the plot

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Aerodynamic Estimation

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: a p e “MN” for o Mach ac number u be MN

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Repeat for velocity, density, Mass, gravitational constant, and center of gravity (minimum). Page 28

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Aerodynamic Estimation

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 de e the t ea angle geo of attac attach,, s side-slip de s p angle, a g e, etc., etc , through 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 y entering g “A” and finally y enter the angle g of attack 4.0 deg

Note: AOA can be constrained by any variable listed (Like CL)

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Aerodynamic Estimation

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)

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Repeat the process for every flight condition or constraint

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Aerodynamic Estimation

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

Downwash angle distribution

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Aerodynamic Estimation

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 ype “LO” O to visualize sua e tthe e wing g loading oad g (p (pressure essu e distribution)

Wing Lift Distribution

Horizontal Tail Lift Distribution

Downwash angle distribution

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Aerodynamic Estimation

3-D Aerodynamics: AVL Vortex Lattice Code To Dump Output AVL to data files: 1) To output 1) 2)) 3) 4) 5) 6) 7) 2)

Stability derivatives type Total ota forces o ces Surface forces (wing, horizontal tail, etc.) Strip forces (lift distribution) Element forces (control points) Strip shear shear, moments (drag and pitching moments) Hinge moments

“ST” or “SB” “FT” “FN” “FS” “FE” “VM” VM “HM”

For each command it will prompt you to provide a file name to write the output. Horizontal Tail Lift Distribution

Downwash angle distribution

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Aerodynamic Estimation

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 od y tthe e reference e e e ce a areas eas mach ac number u be ce center te o of gravity references and CD0 (Vortex lattice methods only predict induced drag!!!!!!)

3)

Modify the fuselage according the description in AVL’s Users guide (avl (avl_doc.txt) 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 p of the fuselage g followed by y the radii from 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.

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Aerodynamic Estimation

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 c o d length, e gt , incidence c de ce a angle gea and da airfoil o ordinate o d ate file e according to the AVL users guide. Notes: 1) The AVL can read the same airfoil data files as xfoil 2) You may use one or more airfoils for this model model. yw XLE3 GIII BL 145 Upper

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GIII BL 45 Upper

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XLE2 Cessna 7500 Upper

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Aerodynamic Estimation

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.

Minimum Deliverables: • •

Drag Polar for each mission segment Lift curve for each mission segment

Basic Procedure: 1. 2. 2 3.

2-D Airfoil selection/analysis (wind-tunnel data or XFOIL) 3 D drag 3-D d b ild build-up (H d b k DATCOM, (Hand-book, DATCOM AVL) 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 USAF Stability and Control DATCOM, 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

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Aerodynamic Estimation

Performance Mission Segments: 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) 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 Take off field length (TOGW)

1 570 m (5 1,570 (5,140 140 ft)

Landing field length (max landing weight)

1036 m (3,400 ft)

Fuel reserves

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45 min at 1,524 km (5,000 ft)

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Aerodynamic Estimation

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)

Minimum Deliverables: • • •

Static stability derivatives at each DCFC Dynamic stability derivatives at each DCFC Control derivatives at each DCFC

Basic Procedure: 1. 2 2. 3. 4. 5.

Outline DCFC’s C Compute t trimmed ti d static t ti stability t bilit derivatives d i ti (DATOM / AVL) Compute dynamic stability derivatives (DATOM / AVL) Compute control derivatives (DATOM / AVL) 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,” 3rd Edition, John Wiley and Sons, Inc, New York, 1996 [3] Torenbeek Torenbeek, E., E “Synthesis of Subsonic Airplane Design,” Design ” Delft University Press, Press London, 1996

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Aerodynamic Estimation

Design Constraining Flight Conditions (DCFC): 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 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. LoCE's c g during low-speed 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

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LaCE's LaCE s ability to bank the aircraft to a required bank angle in the required time time.

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Aerodynamic Estimation

Stability and Control Coefficients and Derivatives: What does the S&C team need? - trimmed Stability and control derivatives Longitudinal

Lateral/Directional

Coefficients

C D0 C L0

Static Derivatives

C D C L C Lu C Du C mu C Lq C mq C L  C m   

Cl  C n  C y  C l p C n C y Cl C n C y p r p r r

C D

Cl

Dynamic Derivatives Control Derivatives

LoCE

Cm0 C D C L C trim trim mtrim Cm

C L

LoCE

C m

LoCE

Cl

LaCE

C n

DiCE

C n

LaCE

C y

LaCE

DiCE

C y

DiCE

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 lt

Lw

V V’

Lt Mact Dt

V Macw

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Dw

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Aerodynamic Estimation

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

Minimum Deliverables: • •

Distributed Aerodynamic Loads for the wing, fuselage and empennage for each critical load case (Pressure Distribution) Aerodynamic forces and moments (CL, CD, CM) for each load case

Basic Procedure: 1. 2. 3.

Outline critical load cases Compute disturbed Lift, Drag and Pitching Moment for each aircraft component Produce look-up tables/figures for each critial load case

Recommended References: [1] Niu, M., “Airframe Structural Design,” Technical Book Company, California, 1990 [2] Hoerner, H S F “Fluid-Dynamic S.F,, “Fl id D i Lift,” Lift ” Midland Midl d Park, P k NJ, NJ 1965 [3] Roskam, J, “Roskam, J, “Airplane Design, Part VI: Preliminary Calculation of Aerodynamic, Thrust, and Power Characteristics,” DARcorporation, Lawrence, Kansas, 2004 [4] Howe, D., “Aircraft Loading and Structural Layout,” AIAA Educational Series, Virgina, g , 2004 [5] Lomax, T., “Structural Loads Analysis for Commercial Transport Aircraft: Theroy and Practice,” AIAA Educational Series, Virgina, 1995

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© G. Coleman / UTA MAE / AVD Lab

Aerodynamic Estimation

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 stabilizerelevator maneuvers

Longitudinal maneuvers which can load the LcCE and main wing.

Aileron and/or spoiler p maneuvers

Lateral maneuvers which apply pp y an asymmetric y loading g condition on the 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 design

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© G. Coleman / UTA MAE / AVD Lab

Aerodynamic Estimation

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. 2. 3.

Quick summary of the capability and limitations of X-FOIL and Digital DATCOM 2-D drag polar from X-FOIL 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

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© G. Coleman / UTA MAE / AVD Lab

Aerodynamic Estimation

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 1. 2. 3. 4.

Quick summary of the capability and limitations of AVL and Digital DATCOM Brief description of the trim method used Table summarizing the stability and control derivatives during Cruise and Approach Comparison of Digital DATCOM and AVL results

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© G. Coleman / UTA MAE / AVD Lab

Aerodynamic Estimation

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. 2. 3.

Quick summary of the capabilities and limitations of the vortex lattice code AVL 3-D wire-frame drawing of the Citation X model 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

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© G. Coleman / UTA MAE / AVD Lab