ME 435 Spring Project Design and Management II. Old Dominion University Department of Mechanical Engineering. Standard Dynamics Model

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1 ME 435 Spring 2011 Project Design and Management II Old Dominion University Department of Mechanical Engineering Standard Dynamics Model William Lawrence Andrew Snead TJ Wignall 15 March 2011

2 Abstract The Standard Dynamics Model (SDM) was developed in the late 1970 s to promulgate standardized testing in wind tunnels across the globe. The design was simplified in order to encourage use by researchers and maintain economic affordability. Since its conception, it has seen use in a variety of testing facilities around the world, including Canada, Germany, and the United States. The amount of test data accumulated from the use of the SDM makes it an asset to any institution interested in comparing data, or introducing dynamic test characteristics and procedures. Engineering professors at Old Dominion University have recognized the benefits of building and validating an SDM for use specifically in undergraduate and graduate coursework. In order to fulfill that requirement our group will model, construct, and validate a scaled version of the SDM for future use by the University for years to come. 2

3 Table of Contents Introduction..5 SDM Modeling 5 Sting Modeling.6 Data Acquisition.7 Immediate Goals.8 Summary.8 References..9 Appendix A Appendix B Appendix C Gantt Chart 3

4 List of Figures 1. Standard Dynamics Model Internal Balance Assembly.6 3. Sting...7 4

5 Introduction: The Standard Dynamics Model (SDM) is a calibration model first introduced by the National Research Council of Canada (NRC) / Institute for Aerospace Research (IAR) in The model is designed to represent a current advanced fighter aircraft configuration with special consideration given to simplifying the geometry to expedite the manufacturing process. These design considerations are intended to promote the widespread use of the model in testing facilities around the world. The SDM consists of an asymmetrical fuselage with flat, tapered lift surfaces. The body has an ogive-cylinder profile and mounts a tapered intake unit with a forward facing flat face and a biconvex, circular canopy (Beyers). The geometrical layout and relevant dimensions are given in Figure 1. The model is best suited for use in measuring the dynamic derivatives through all axes of flight at low and high angles of attack. Researchers at Old Dominion University will be able to test these dynamic characteristics and compare the data to published literature for a variety of different wind tunnel configurations and flow geometries. The model is mounted on a calibrated test balance assembly (Figure 2) designed to deflect when exposed to loading forces. This test balance will send the data to the computer software to be converted in usable data depending on the test being conducted. The design balance was obtained from the Aerospace Engineering department, and was not designed by our team. In order to facilitate undergraduate and graduate flight dynamic testing, our team will model and build an SDM for Old Dominion University. SDM Modeling: As intended, the design process is simple. The first step is to scale the model to fit the wind tunnel intended for use. The low speed tunnel at Old Dominion measures 3 by 4 ; therefore, a model with a 1 wingspan will provide sufficient clearance 5

A comprehensive force analysis conducted using hand calculations and the modeling software allowed us to measure the force loading on the model.

6 for the model to move through the desired testing envelope. Since the model is standardized with a constant aspect ratio, designing the model using 3-D modeling software is simply a process of scaling and drawing. A comprehensive force analysis conducted using hand calculations and the modeling software allowed us to measure the force loading on the model. Results were obtained using the force coefficients found in (Huang), and the model was found to have no more than 80% of the allowable loading at any given angle of attack. Detailed calculations regarding the maximum allowable force coefficients may be found in Appendix A. Currently, detailed engineering drawings have been submitted to the ODU machine shop for cutting and fitting. Job completion is a function of the shop s workload and manpower availability with an expected completion time of 1-2 weeks. As of now, the shop is building the fuselage, wings, ventral fins, horizontal stabilizer, vertical tail, and bulkhead assembly. The engineering drawings can be found in Appendix B. Figure 1: Standard Dynamics Model Figure 2: Internal Balance Sting Modeling: The primary method of testing will be the utilization of an internal balance assembly provided by the Aerospace Engineering department of Old Dominion 6

University. This balance contains internal strain gauges that measure the minute flexure of the model under a variety of test characteristics.

7 University. This balance contains internal strain gauges that measure the minute flexure of the model under a variety of test characteristics. The balance provides measurements for normal, side, vertical, axial, roll, and yaw forces. In order to mount the balance to the model, an internal bulkhead assembly will be machined inside of the forward fuselage. The front of the balance will fit into the bulkhead while the back of the balance will mount into the forward part of the sting utilizing a slotted keyway and two setscrews. The sting (Figure 3) measures approximately 14 inches and contains slots that allow the balance wiring to be routed clear of the pitch crescent and other moving parts. The sting attaches to the pitch crescent at its far end utilizing three counter-bored screws. Figure 3: Sting Assembly Data Acquisition: In order to validate the model, it is essential that it is tested through various wind envelopes at varying degrees of angle of attack. This testing will determine if the design parameters set for the SDM have been met and set a benchmark for our model that enables undergraduate and graduate students the ability to publish results found using 7

8 the model. We will use LabView as the primary means of data collection, with a program written by our design team. In order to implement the balance data into the software, a special calibration matrix has been provided by the Aerospace department. Once collection of the test data is complete, it will be analyzed and furthering design or testing will be conducted as necessary. Immediate Goals: At this point, our team has a series of immediate goals required to finish the project before the end of the semester. First, the balance calibration matrix has to be implemented into the LabView software and the test program has to be written and debugged. Secondly, the model and sting have to be returned, assembled, and tested. After the completion of these primary goals, our team will be able to move into the analysis phase and ultimately validate our model. Summary: Recognizing the benefits of having a validated Standard Dynamics Model, Old Dominion University has moved forward with the process of designing and building one. Once validated thorough comparison with published literature, the model will be beneficial to undergraduate and graduate level work here at the University. The model is relatively inexpensive to build and simple in design in order to facilitate its use at testing facilities around the world. At present, we are complete with the design phase of the physical systems and are currently awaiting the finished product from manufacture. Concurrently, we are designing the test software and environment necessary to validate our model. 8

9 References Beyers, M.E., Moulton B.E. Stability Derivatives Due to Oscillations in Roll for the Standard Dynamics Model. Ottawa: National Research Council Canada, Huang, X.Z. Wing and Fin Buffet on the Standard Dynamics Model. Ottawa: IAR/NRC Canada,

10 Appendix A SDM Scaling Calculations Constants: Normal Forces (Z): Zmax = N m^2 Pitch (M): Mmax=4.519 N-m 10

11 Roll (L): Lmax=.904 N-m Yaw (N): Nmax=2.712 N-m.03 m^2 Side (Y): Ymax= N.04 11

12 Results Normal forces, Zmax= N, resulted in the smallest allowable wing area, S= m^2. When comparing the area we determined to the area for the experiment given a scaling factor of 87% was found. Using the equation,, we found the wing span of our model to be m^2 (1.86 ft). We thought that this wing span would be too large for our wind tunnel, and used the published ratio of wing span to tunnel height of Since our tunnel height is 3 ft, the wing span of our model is 1 ft. This is smaller than the maximum area allowed 1.86 ft. 12

13 Appendix B A-1: Plane Assembly A-2: Plane Exploded View 13

14 A-3: Plane Slice View A-4: Bulkhead 14

15 A-5: Fuselage Main A-6: Fuselage Slot Locations 15

16 A-7: Fuselage Slot Dimensions A-8: Aft View 16

17 A-9: Fuselage Bolt Hole Locations A-10: Fuselage Bolt Hole Dimensions 17

18 A-11: Bolt Hole Locations Aft View A-12: Bolt Hole Aft View 18

19 A-13: Horizontal Tail Fin A-14: Ventral Fin 19

20 A-15: Vertical Tail A-16: Wings 20

21 A-17: Wings without Taper 21

22 Appendix C Stress Analysis Report Analyzed File: Derived Part of Fuselage and Wing.ipt Autodesk Inventor Version: 2011 (Build , 239) Creation Date: 11/16/2010, 4:23 PM Simulation Author: Andrew Snead Summary: Project Info (Properties) Summary Author Andrew Snead Project Part Number Designer Cost $0.00 Date Created Status Derived Part of Fuselage and Wing Andrew Snead 11/16/2010 Design Status Work In Progress Physical Material Density Mass Area Volume Center of Gravity Aluminum lbm/in^ lbm in^ in^3 x= in y= in z= in Note: Physical values could be different from Physical values used by FEA reported below. 22

23 Simulation:1 General objective and settings: Design Objective Single Point Simulation Type Static Analysis Last Modification Date 11/16/2010, 4:17 PM Detect and Eliminate Rigid Body Modes No Advanced settings: Avg. Element Size (fraction of model diameter) 0.1 Min. Element Size (fraction of avg. size) 0.2 Grading Factor 1.5 Max. Turn Angle 60 deg Create Curved Mesh Elements Yes Material(s) Name Aluminum-6061 Mass Density lbm/in^3 General Yield Strength psi Ultimate Tensile Strength psi Young's Modulus ksi Stress Poisson's Ratio 0.33 ul Shear Modulus ksi Expansion Coefficient ul/f Stress Thermal Thermal Conductivity btu/( ft hr f ) Specific Heat btu/( lbm f ) Part Name(s) Derived Part of Fuselage and Wing 23

24 Operating conditions Pressure:1 Load Type Pressure Magnitude psi Selected Face(s) Fixed Constraint:1 Constraint Type Fixed Constraint Selected Face(s) 24

25 Results Reaction Force and Moment on Constraints Reaction Force Reaction Moment Constraint Name Magnitude Component (X,Y,Z) Magnitude Component (X,Y,Z) Fixed Constraint: lbf Result Summary lbf Name Minimum Maximum Volume Mass in^ lbm Von Mises Stress ksi ksi 1st Principal Stress ksi 3rd Principal Stress ksi 0 lbf ft 0 lbf lbforce ft lbf ft 0 lbf 0 lbforce ft ksi ksi Displacement 0 in in Safety Factor 15 ul 15 ul Stress XX ksi ksi Stress XY ksi ksi Stress XZ ksi ksi Stress YY ksi ksi Stress YZ ksi ksi Stress ZZ ksi ksi X Displacement in in Y Displacement in in Z Displacement in in Equivalent Strain ul ul 1st Principal Strain ul ul 3rd Principal Strain ul ul Strain XX ul ul Strain XY ul ul Strain XZ ul ul Strain YY ul ul Strain YZ ul ul Strain ZZ ul ul 25

26 Gantt Chart 26

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