Guide for Pressure-Sensitive Paint Testing at NASA Ames Research Center Unitary Plan Wind Tunnel

Guide for Pressure - Sensitive Paint Testing at

NASA Ames Resea r ch Center Unitary Plan Wind Tunnel

Nettie H. Roozeboom, N ASA Ames Research Center, Moffett Field, CA 94035 Jennifer K. Baerny , Jacobs Technology, Moffett Field, CA 94035 Optical measure me nt techniques have become a standard option for wind tunnel tests.

Pressure - sensitive paint (PSP) is a mature test technique and a common experimental technique in many wind tunnels to measure the global mean static p ressure on a model. PSP is a valuabl e tool when a more detailed distribution of the pressure is needed rather than the conventional pressure taps alone. Planning for a test with optical - based techniques can present new challenges even for experienced customer. The purpose of this paper is to provide a resource to the wind tunnel testing community and customers interested in obtaining PSP measurements on a wind tunnel model at the NASA Ames Research Center’s Unitary Plan Wind Tunnel. An overview of PSP mechanics , a list of requirements for on es considering PSP measurements, and PSP deliverable details are specified .

I. Introduction he development of pressure - sensitive paint (PSP) technology spans almost 4 decades. Go vernment agencies and labs, universities, and commercial companies, have collaborated and developed the technology together.

The historical background of PSP has an interesting and inspiring beginning, and like most cutting edge T technologies, simultaneously in many countries around the world, United States, Germany, Russia, an d Japan, had a 1,2 hand in the early development of the technology . Through this collaboration and years of development in the paint’s chemical make - up, software development, and advancement in hardware, there are numerous applications and techniques that exploit the chemistry of luminophore s , the essence of pressure - sensitive paint. The variety PSP applications across NASA centers present an example of the diversity of applications. At NASA Langley Research Center in Hampton, VA, Watkins , et al. have developed a system for measuring global surface pressure on rotorcraft blades. Watkins’s system used a single laser pulse , and data is acquired using the lifetime PSP method.

At NASA Glenn Research Center in Cleveland, Ohio, Bencic applies PSP and TSP (temperature - sensitive paint) to scale - model fans. In recent years at NASA Ames Research Center, PSP has been geared towards application in production - style wind tunnels like the Unitary Plan Wind Tunnel 11 - by 11 - f oo t Transonic Wind Tunnel and 9 - by 7 - foot Supersonic Wind Tunnel. The PSP system is deployed as a test - dependent technique per each customer’s request.

The pressure - sensitive paint technique implementation at NASA Ames Research C enter’s Unitary Plan Wind Tunne l , has improve d over the past deca de. The PSP system has been integrated as part of wind tunnel data system.

Through a strong collaboration with the United States Air Force (USAF) for more than fifteen years, NASA and the USAF have collab orated and shared costs to develop a common system . At Arnold Engineering Development 5,6 ,7 8 Center (AEDC) , at Arnold Air Force Base, Tennessee, Sellers and Ruyten developed a multi - camera, portable PSP system that integrates into a production - style wind tunne l. In 2008 , NASA Ames Research Center and AED C began to collaborate by using the same software developed by Ruyten . The cost and kno wledge sharing has proven to be a beneficial investment for both organizations .

A. Introduction Aerospace Engineer, Experimental Aero - Physics Branch, M.S. 260 - 1, AIAA Member.

Instrumentation Engineer, Wind Tunnel Instrumentation Branch, M.S. 227 - 5.

American I nstitute of Aeronautics and Astronautics For each PSP test, up to eight scientif ic - grade cameras and up to 40 (400 - nm wavelength) Light Emitting Diodes ( LED ) lamps are mounted around the test section. The wind tunnel model is sprayed with the pressure - sensitive paint. The paint contains luminescent molecules that fluoresce when excited by the light source at an intensity proportional to the surface pressure.

NASA Ames uses the ‘lifetime’ technique to acquire steady - state PSP data. With the ‘lifetime’ technique, two images are required for each data point, gate 1 and gate 2. Gate 1 image records the paint’s lu minescence coincident with the light source, while the gate 2 image is taken after the li ght source has been turned off and measure s the lu minescent lifetime of the paint. Figure 1 depicts the luminescent response and decay at various pressures.

Figure 1. Luminescent Response and Decay versus Time for Varying Pressure 1 0 The other standard data reduction approach is the ‘intensity’ or ‘radiometric’ technique . With the ‘intensity’ technique, instead of taking the ratio of two images with wind on, a ratio of a wind - off image to a wind - on image is computed. Comparing the two techniques, the luminescent lifetime approach offers greater immunity to model motion and temperature changes. Each two - exposure data point requires 3 - 7 seconds depending on the tunnel conditions (Mach, Total Pressure).

The pressure - sensitive paint technique exploits the oxygen sensitivity of luminescent molecules. A luminescent molecule is excited by a high energy photon followed by emission of a l ower energy photon. As depicted by the 1 1 Jablonski diagram in Figure 2, w hen luminescent molecules are excited to a higher energy state by an energy source and allowed to decay back to the ground state, the time required for the emission intensity to drop by a factor 1,1 0 of e is the luminescent lifetime , If the excitation pulse ends at time 0, the emitted intensity at that time is I , the emission decays expon entially following the relationship: – t / τ I = I e where I is the emitted intensity, t is the time and τ is the lifetime.

Materials suspended in an oxygen - permeable binder like the luminescent probe molecule in PSP, are also reaching with oxygen molecule s in the air causing the luminescent molecule to be ‘quenched’ by the oxygen molecule s, losing excitation e nergy, and therefore not emitting as much luminescent energy emitted . Intensity of the PSP emission and local oxygen concentration have an inversely proportional relationship. Higher quantities of oxygen, i.e. higher pressure, resul t in a lower intensity emitted by the pressure - sensitive paint .

American I nstitute of Aeronautics and Astronautics Figure 2. Jablonski Diagram Depicting Excitation and Decay of a Luminescent Molecule s B. Facility This PSP system discussed in this paper is deployed at NASA Ames Research Center’s Unitary P lan Wind Tunnel (UPWT) facility. NASA Ames Research Center’s Unitary Plan Wind T unnel consists of the 11 - by 11 - f oot Transonic Wind Tunnel (TWT) and the 9 - by 7 - f oot Supersonic Wind Tunnel (SWT). The 11 - by 11 - f oot TWT lends itself nicely to optical measure ment techniques with multiple windows on each wall of the tunnel. As show in Figures 3 and 4 below, the side walls have a large amount of optical access, and the ceiling and floor wall have several windows allowing viewing access of the whole model. Addi tional windows have been added to the 11 - by 11 - foot TWT, as shown in Figure 4, to allow for more optical access and multiple optical techniques to be employed at the same time. More over, research oriented tests, like the capsule wake - deficit study , in Figure, or the NASA / Boeing Truss Bra ced Wing (TBW) test in Figure 4, will exercise as many as 4 optical techniques at the same time.

PSP, Infrared (IR) thermograph y , shadowgraph / Schileren, Particle Image Velocimetry (PIV), and model deformation me asurements (MDM) are test - dependent systems offered at the UPWT.

Figure 3. NASA Generic Capsule Model Installed in the 11 - by 11 - foot Test Section American I nstitute of Aeronautics and Astronautics Figure 4 . NASA / Boeing Truss Braced Wing Model Installed in the 11 - by 11 - foot Test Section Most customers testing at UPWT and requiring PSP measurements will test at the 11 - by 11 - foot Transonic Wind 16,17 Tunnel (TWT ) This wind tunnel has a Mach number range of 0.2 – 1.4. The Reynolds number may be adjusted by varying the total pressure in the wind t unnel from 0.2 to 2.2 atmospheres. The test section w alls are slotted and allows flow into and out of a plenum that surrounds the test section. The 11 - by 11 - f oot TWT test section has windows on each wall of the test section allowing many cameras, lamps, a nd optical equipment to be mounted in the plenum. Figures 5 and 6 present model drawings of the test section and the location of the rectangular windows with respect to the model location.

Figure 5. Top View of 11 - by 11 - foot Transonic Test Section American I nstitute of Aeronautics and Astronautics Figure 6. Side View of 11 - by 11 - foot Transonic Test Section Optical access at the 9 - by - 7 SWT is not as ideal as the 11 - by 11 - f oot, however PSP data can still be acquired.

Depending on the model size, it can be challenging to compute loads from PSP da ta since coverage of the model may not be complete, d epending on the model and lighting relative to the windows .

II. Wind Tunnel Model and Instrumentation When a customer is interested in optical measurement data like PSP , several items should be consider ed : model material, stiffness of sting and balance , duration of data points, and visibility of region of interest . With the increase in optical data, more attention needs to given to the stiffness of the sting and balance . If there are large vibrations, images will be blurry or smeared. Since steady - state PSP is two images taken over several seconds , the ratio of these two blurry images will not compare the same physic al location on the model producing a solution with large errors. In addition, since P SP offers a solution to areas that are challenging to instrument with traditional pressure taps, it can often be misleading or present an unachievable solution. PSP is a balance of trade offs, and when designed and implemented correctly can provide a stro ng, accurate, necessary data set. There are 3 items to consider: PSP ca n only take measurements on model parts that can be painted, viewed by at least one camera, and ability to excite the paint Figure 7. TBW Model with PSP Installed at with energy source (LED lamp).

11 - by 11 - foot Transonic Test Section If the camera cannot see a r egion o f interest, then PSP data canno t be accurately acquire d .

American I nstitute of Aeronautics and Astronautics Questions for customer to consider are: why is PSP important or useful, and who will be using the PSP data?

The answer to these questions will help direct the focus of PSP. The re are several problems that PSP can be used to solve. A majority of customers are interested in a global static pressure distribution. This could be used on models that have a range of pressure taps from a dozen to over a hundred in quantity. PSP is use d to obtain pressure values on areas that are hard to instrument, like a wing - body junction or a thin airfoil, as seen in Figure 7, or control surfaces - areas that are too thin to instrument with a conventional pressure tap.

Since PSP inherently has hig h spatial resolution, and the area of the model is well known, the loads experience by components of the model can be computed, however, it is extremely important to know the expectations of computed loads. When a customer is interested in using PSP to co mpute integrated loads on a control surface, it is important to build the PSP grid and design the instrumentation layout with these areas carefully defined. Full - body integrated PSP loads can be compared to balance loads, however, a few words of caution s hould be shared. If areas of the model are not viewable to any camera, then loads cannot be computed for that area. In some cases, pressure tap values can be applied to an area for computing the load. Pressure taps are not always in regions with poor vi ewing angles, however. It is often best to use incremental changes in integrated load between points and rather than overall computed loads.

For extremely complex wind tunnel tests or models, like launch abort simulation tests using high pressure air to simulate abort nozzles and a balance instrumented with delicate bellows, PSP can be used as a backup to the balance. There have been examples of supplementing aero - databases with a blend of PSP and Computational Fluid Dynamics (CFD) data to fill in region s of the database where balance data does not follow the trends of the tests. In these case, careful attention has to be made on what PSP data and what CFD data is used to supplement the database .

Lastly when comparing balance loads to PSP computed load s, it is best to compare normal and side forces.

Axial forces computed from the balance will contain drag forces due to pressure and shear. PSP only measures the drag due to pressure and does not sense the skin friction.

III. PSP Requirements and Deliverable s A. Pre - T est PSP Requirements Some customers plan months in advance of their test entry and have well thought out plans for PSP data collection and analysis. Other customers reuse an existing model with a couple dozen pressure taps and delay thinking about PSP until much later in their planning phase. In either case, the first step in planning for PSP tests is simulating the camera views of the wind tunnel model on the actual mounting hardware in the wind tunnel. This exercise aids discussions on what are the priorities when PSP data is collected, where to install PSP cameras, does the PSP installation hamper any other optical equipment or model views, like shadowgraph, what resolution or lens is needed on each camera. Custom software, Vinci, was develope d at NASA Ames Research Center by Edward 19,20 Schairer . Vinci is used before each test to virtually model the wind tunnel, wind tunnel model and optical equipment. A low - resolution model, less than 20 MB, stereolithography (.STL) file is pre ferred. Figures 8 and 9 shows example simulated views for a recent test. Modeling of the lamps and cameras is used to inspect and optimize their locations for best model illumination levels. Since access to the wind tunnel is a limited (and expensive) c ommodity, advanced planning of the lamp and camera locations and what lenses to use, the physical installation of the equipment is predictable and requires less time. Designing the equipment layout should occur several months before the test is scheduled to run.

American I nstitute of Aeronautics and Astronautics Figure 8 . Side View using Vinci Figure 9 . Cam era View using Vinc i At least 3 months before the test, a detailed computer - aided drawing (CAD) file of the wind tunnel m odel needs to be delivered. Having a correct, detailed CAD file is important for clearly defining the regions of interest. For customers requesting PSP - computed loads on controlled surfaces, sections of wings, or vehicle windows, the detailed CAD file mu st give clear definitions of these boundaries that will be defined as a ‘zone’. The final format of the grid is Plot3D, single precision, unstructured, little endian, multiple zone grid with no I - blanks. Generating the grid is the most intensive part of the pre - test process and can take 2 months or more depending on the model complexity. This is the grid onto which the PSP pressures are mapped so it must be carefully prepared well in advance of the test.

One month before the test, the pressure tap co - ord inates should be delivered. The tap locations should be part of the quality assessment report done by the model manufacture after the pressure taps have been installed. The tap pressure measurements are used to anchor the PSP data. An average PSP value at the tap location is computed, and compared with the average pressure tap value. A pressure offset is applied to the PSP data given the deltas between the tap data and PSP data.

B. Painting Requirements Two weeks before the start of the section, model bu ild - up activities will occur in a model prep rooms. During this two - week window, balance check loads , model build - up, and instrumentation check out will occur. If PSP is a requirement for the test, there will be two stages of painting. First an epoxy pr imer coat is sprayed onto the model.

The PSP adheres better to the epoxy layer better than bare metal. Depending on the model complexity and number of model parts, the process will take 2 – 4 hours. A 12 - hour cure is required after the epoxy has been sp rayed. The following day, the model will be sanded and prepared for PSP application. Trip dot application is different for each test since trip dot requirements may change. It is most common to apply the trip dots after the epoxy primer layer but before the PSP application.

The PSP application requires two different paints. UPWT purchases paint from Innovative Scientific Solutions, Inc. (ISSI). The first layer is a white base coat consisting of titanium dioxide , which serves as the white pigment, and the proprietary FIB - 7 polymer developed by the University of Washington. The base coat provides a uniform white surface, helpful f or reflecting excitation light and reducing illumination errors. The white base coat also enhances the PSP emission by refl ecting the luminescent emission away from the model surface and towards the camera sensor. The second coat is the active layer or PSP layer. This layer contains the University of Washington proprietary FIB - 7 polymer and the luminescent molecule Platinum Tetra Pentaf luouophenyl Porphine (PtTFPP) as the probe molecule. PtTFPP is used frequently as pressure sensor because of its high quantum efficiency and low 2 1 ,2 2 temperatu re sensitivity . The pressure - sensitive paint in reality is an oxygen - sensitive pai nt since the FIB7 polymer is porous to oxygen molecules, allowing for the interaction of the luminophore, PtTFPP, and the oxygen in the air , which is proportional to pressure . The PSP layers can take 6 - 10 hours to apply. After the paint has been applied , the paint must be given time to cure. To accelerate the cure t ime, an oven is constructed around the model, and the model is baked at 140˚F for 4 hours. Once the paint is applied, there is no opportunity to ‘touch - up’ the American I nstitute of Aeronautics and Astronautics paint. The customers must tre at the paint with extreme care and caution with the understanding oils and solvents will damage the paint, degrading the data. The total thickness of epoxy plus PSP base and top coat is approximately 1 – 1.5 thousandth of an inch. Approximate roughness i s 75 - 100 microinches.

C. Equipment Installation The PSP equipment is installed before the model arrives to the test section. The hardware installation is time intensive and requires approximate 30 – 40 hours. The stan dard equipment installation is 8 camer as and 40 LEDs.

The cameras are Roper Scientific CoolSNAP K4 interline transfer cameras with Kodak KAI4040M (2048x2048) 2 1 CCD sensors operated in accumulation mode . Two cameras are mounted on each wall in an effort to have double coverage of most points on the mode l . The paint is excited by ISSI’s LM4X blue LED (400 - nm) lamps. Ten LEDs are installed on each wall in an effort to illuminate the model as uniformly as possible.

D. Calibrations and Data Collection Once the model has been installed, final poin ting angles and focal lengths are set. This process requires the model to be on centerline for approximately four hours. Several calibrations are required once the model is installed and camera focal lengths have been finalized. One calibration is for i nterior parameters of the camera (focal length, 2 3 distortion), and the second calibration is for exterior camera parameters (location and orientation in the tunnel) .

These calibrations are essential in the automation of the processing and must be completed after the model has been installed in the tunnel and before PSP data collection begins.

Before starting the wind tunnel, a final set of calibration images are needed at several different tunnel static tunnel pressures. This set of images is referred to a s the ‘pump - down’ images. If testing below atmosphere, the images are usually acquired at atmosphere, 1600 psf (pounds per square foot) , 1200 psf, and 800 psf. If testing above atmosphere, the images are usually acquired at atmosphere, 2400 psf, 2800 psf , and 3200 psf. These images are used to correct for any non - uniformity in paint or lighting. These calibration images need to be collected before coming online after a model change since new parts being installed on the model will have a different respo nse than t he parts that have been exposed to the PSP lamps and therefore the paint has not degraded due to lighting. The paint will last for more than two weeks of testing double shifts, but by the end of a two - week, double - shift test, the paint has degra ded mostly from model changes.

E. PSP Deliverables Once online, the goal is have preliminary , processed data available to the customer in near - time. PSP image data are reduce d , and a series of calibration are applied to convert the raw intensity values to pressure coefficient (C ). A p complete pressure map of the painted surface is produced for each test condition (data point). PSP data are typically 2 4 accurate to <1% of tunne l total pressure. The PSP data are provided as a PLOT3D type function file for e ach data TM point. Tecplot or other P3D viewers are suggested for viewing the PSP data. The grid file typically ends in .grid, and the solution file will be rrrrss.p3d, where r is a four digit run number , zero - padded , and s is a two digit sequence number , zero - padded . For example, Run 105 Sequence 6 would be 010506.p3d. A comma separated variable ( . csv) file is also delivered. This file contains the tunnel conditions (Mach, alpha, beta, phi, ect), computed loads from PSP (if desired), and lists Cp of eac h tap and the PSP C value at each tap location. If a customer desires to see the PSP p C value at certain locations, say along a given c h ord or along the x - axis of a launch vehicle, ‘virtual’ taps can be p entered, and the PSP Cp value at that x,y,z locatio n will be reported in the data file. There is a csv file for each run an d is named r.dat, where r represents the run number.

F. Customer Considerations When employing pressure - sensitive paint into a wind tunnel test, additional considerations need to be ma de.

First, it is important to reflect on what tunnel conditions are desired and are they the optimal test conditions for PSP.

Since PSP response to oxygen, the lower the oxygen content in the air, the less excitation is needed since the luminescent molec ule are quenched by the oxygen. If the results are not Reynolds - dependent, it is suggested to run at a lower Reynolds number. If higher Reynolds numbers are necessary, PSP data collection will take 2 - 5 seconds longer per data point. Second, it is import ant to understand the model support system at the test facility and consider the alpha, beta range needed for the PSP portion of the test. Like most engineering problems, there is a tradeoff and a compromise must be made between resolution and range of da ta. The model support system at UPWT has a knuckle - sleeve, meaning the model support is a pitch, yaw system. The model and sting are mounted on the model support strut. The strut can mov e up and down to compensate for pitching the model in positive or ne gative alpha, leaving the center of rotation in the center of the tunnel. However, there is no compensation when the model is yawed. This is a detail to keep in mind for optical - based measurements, li ke PSP. As shown in the figure 9 below, American I nstitute of Aeronautics and Astronautics the camera is mounted in the ceiling looking down at the floor. The first image is with the model , a generic launch vehicle , at alpha, beta (0,0). The second image is with the model pitched to ( - 4,0), and the third image is with the model yawed at (0, - 4). The imag es shown below were calibration images taken while calibrating the camera positions. This test was ran at beta = 0. There is very little difference when the model is pitched in the alpha plane, but the model will move out of the field of view when yawed. It is acceptable to yaw the model when testing with PSP, but a lens with a shorter focal length will be installed. It is important to know the alpha, beta range when modeling the wind tunnel model in the wind tunnel using Vinci, as mentioned above. Inst alling a shorter focal length lens will mean less of the sensor is used per data point. This means lower resolution of actual wind tunne l model area per camera pixel. However, PSP can be used on tests that do yaw the model in beta and produce quality res ults.

Figure 9 a. Model at (0,0) Figure 9 b. Model at ( - 4,0) Figure 9 c. Model at (0, - 4) Figure 9 . Image of Model Location in Tunnel with various Alpha, Beta Combinations.

G. Safety Considerations I t is important to note the PSP paint requires working with chemicals that are known hazards. Care has been taken to mitigate these hazards for customers and personnel. While applying epoxy and PSP layers, customer and non - essential personnel are removed f rom location. Personnel applying these layers wear PPE including respirators, coveralls, and hand/eye protection. Considerations for adequate ventilation in the painting locations, such as the ‘wall - of - fans’ used in the model prep room consisting of 16 b oxed fans used to pull air through the room, have been implemented.

The PSP paint hazards are minimal once the model has cured and baked but to protect the paint, the PSP layers should not be touched. During model installation/changes it is imperative to wear gloves to protect the paint from the oils from skin contact. Additionally, it is recommended to follow good industrial hygiene practices such as washing your hands after working with the model.

It should also be noted that the lamps used to excite the paint are UV - A. Under normal test operations, all customers and wind tunnel personnel are excluded from areas surrounding the test section to limit exposure to UV light. Some of the calibrations steps do require personnel to be in the test section wh ile the UV lights are pulsed.

For these instances, personnel take care to limit exposure to skin and protect eyes with UV safety glasses.

IV. Reduced Results To best guide customers on planning PSP test matrix, several tests worth of data have been combined to examine what errors with PSP could be expected. The data below , in Figure 10, shows the absolute average difference between coefficient of pressure (C ) and the PSP at the same location for various Reynolds numbers.

P American I nstitute of Aeronautics and Astronautics Figure 10. Absolute Aver age between taps and PSP at same location Figure 10 shows an average difference between the tap value and the PSP value at the given tap location. Each line represents a different model or configuration for a given Reynolds number. Testing below Mach 0 .6, will introduce a larger signal to noise ratio contributing to a larger difference between the tap and the PSP values. At the example above for a Reynolds number of 1 Million/Ft and 3 Million / Foot, there are significant model vibrations at Mach 1.0 a nd Mach 1.2 , respectively, contributing to a larger differences between the tap and PSP values.

V. Future Work With the increase in interest of optical - based techniques, researchers at NASA Ames Research Center UPWT are developing coatings and techniques to enable PSP, IR the r mography, and MDM systems to be deployed and acquire data in parallel. Paint roughness and paint application need to be explored and improved, as well as, improving how final data is reported in the best, coherent way to the customer a nd combined with wind tunnel balance and pressure data.

25 ,26 The research and advancement of unsteady PSP has gained interest. In November 2015, a test investigating the use of unsteady PSP sponsored by the NASA Engineering and Safety Center (NESC) was ra n at NASA Ames Research Center’s Unitary Plan Wind Tunnel in collaboration with Arnold Engineering Development Center at Arnold Air Force Base, TN. The UPWT is currently developing an unsteady PSP system for production - style wind tunnel testing.

VI. Acknow ledgments The authors would like to thank the NASA Aeronautics Evaluations and Test Capabilities (AETC) (formally the NASA Aeronautics Test Program (ATP)) for the support and funding of the PSP equipment. The authors would like to thank the hard working staff at the NASA Ames Research Center Unitary Plan Wind Tunnel. This dedicated crew deserves much respect and appreciation. They have had a tremendous impact on the aerospace industry for the last 60 years. The lead author would also like to thank Matt Krakenbe rg and Bill Browning of Jacobs Technology, Moffett Field, CA. Mrs. Roozeboom would like to thank Mr. Marvin Sellers for lending his time, patience, and expertise to sharing the exciting world of PSP. Mrs. Roozeboom would also like to thank Dr. W im Ruyten for sharing his PSP expertise and dedication to the software development. Lastly, Mrs. Roozeboom would like to thank Dr. Rabi Mehta, Dr. James Bell, and Dr. Jim Ross for your guidance, leadership, mentorship and for exposure to the world of pre ssure - sensitive paint.

VII. References Brown, Owen C., “Low Speed Pressure Measurements Using a Luminescent Coating System,” Stanford University Ph.D Dissertation, May 2000.

Banke, Jim. “Power of Pink Provides NASA with Pressure Pictures.” NASA.gov, NASA, 3 August 2016.

American I nstitute of Aeronautics and Astronautics Watkins A.N., Leighty, B.D., Lipford, W.E.,Wong, O.D., Goodman, K.Z., Crafton, J. Forlines, A., Goss, L.P. Gregory, J.W., Juliano. T.J. "Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Bla des in Simulated Forward Flight", AIAA Paper 2012 - 2756, 28th Aerodynamic Measurement Technology, Ground Testing, and Flight Testing Conference, New Orleans, Louisiana, June 2012.

Bencic, T.J., "Rotating Pressure and Temperature Measurements on Scale - Model Fans Using Luminescent Paints", AIAA 1998 - 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Cleveland, Ohio, 1998.

Sellers, M.E., "Advances in AEDC's Lifetime Pressure - Sensitive Paint Program", AIAA 2005 - 7638, 2005 U.S. Air Force T&E Days , U.S. Air Force T&E Days Conferences, Nashville, Tennessee, December 2005.

Sellers, M.E., "Application of Pressure Sensitive Paint for Determining Aerodynamic Loads on a Scale Model of the F - 16C", AIAA 2000 - 2528, 21st Aerodynamic Measurement Technology and Ground Testing Conference, Denver, Colorado, June 2000.

Sellers, M. E., “Demonstration of a Temperature - Compensated Pressure Sensitive Paint on the Orion Launch Abort Vehicle,” AIAA Paper 2011 - 3166, AIAA Applied Aerodynamics Conference, Honolulu, Haw aii, June 2011.

Ruyten, W.M., Sellers , M.E., "On - Line Processing of Pressure - Sensitive Paint Images", Journal of Aerospace Computing, Information, and Communication, Vol. 1, No. 9 (2004), pp. 372 - 382.

Ruyten, W. M. “Automatic Image Registration for Opti cal Techniques in Aerodynamic Test Facilities.” AIAA Paper 2004 - 2400, 24th AIAA Aerodynamic Measurement Technology and Ground Testing Conference, Portland, OR , July , 2004.

1 0 Bell, J.H., “Pressure - Sensitive Paint Measurements on the NASA Common Research M odel in the NASA 11 - ft Transonic th Wind Tunnel ”, AIAA 2011 - 1128, 49 AIAA Aerospace Sciences Meeting, Orlando, Florida, January 2011.

1 1 A. J. W. G. Visser and O. J. Rolinski. Basic photophysics. American Society for Photobiology. (2010) Available: http:// www.photobiology.info/Visser - Rolinski.html . Last accessed May 201 3 .

Ross , J.C, Heineck, J.T., Halcomb , N.V , Yamauchi, G.K., Garbeff, T., Burnside, N., Kushner, L. Sellers, M.E.

st “ Comprehensive Study of the Flow Around a Simplified Orion Capsule Model ” , AI AA 2013 - 2815, 31 AIAA Applied Aerody namics Conference, San Diego, California , 2013.

Drain, B.A, Schairer, E., Kushne r , L., Heineck, J.T., “ Model Deformation Measurements of the Truss - Braced Wing th Aircraft in the NASA Ames 11 - By 11 - Ft Transonic Wind Tunn el,” AIAA 2017 - 1054, 55 AIAA Aerospace Sciences Meetings , Grapevine, Texas , January 2017.

Garbeff, T., “ Recent Advancements in the Infr ared Flow Visualization System for the NASA Ames Unitary Plan Wind th Tunnels”, AIAA 2017 - 1051, 55 AIAA Aerospace Scie nces Meetings, Grapevine, Texas, January 2017.

Kushner, L., Schairer, E., Heineck, J.T., Bell, J.H., “Model Deformation and Optical Angle of Attack Measurement System th in the NASA Unitary Plan Wind Tunnel ”, AIAA 2017 - 1052, 55 AIAA Aerospace Sciences Mee tings, Grapevine, Texas, January 2017.

Amaya, M. A., and Boone, A. R., “Calibration of the 11 - by 11 - Foot Transonic Wind Tunnel at the NASA Ames Research Center,” AIAA 2005 - 4277. AIAA 41st AIAA/ASME/SAE/ASEE Joint Pro pulsion Conference and Exhibit, Tucso n, Arizona , July 2005.

Kmak, F. "Modernization and Activation of the NASA Ames 11 - by 11 - Foot Transonic Wind Tunnel", AIAA 2000 - 2680, 21st Aerodynamic Measurement Technology and Ground Testing Conference, Denver, Colorado, June 2000.

Childs, R.E., Gar cia, J.A, Melton, J.E., Rogers, S.E. Shestopalov, A.J. Vicker, D.J., “Overflow Simulation Guidelines for th Orion Launch Abort Vehicle A erodynamic Analyses.” AIAA 2011 - 3162, 29 AIAA Applied Aerodynamics Conference, Honolulu, Hawaii, June 2011.

Schairer, E . T., Heineck, J. T., Walker, S. M., and Yaste, D. M., “Predicting Camera Views for Image - Based Measurements in Wind Tunnels,” AIAA Paper 2005 - 1349, 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, Jan. 10 - 13, 2005.

Kushner, L. K., “Planning I mage - Based Measurements in Wind Tunnels,” AIAA 2011 - 930, 49th AIAA Aerospace Sciences Meeting and Exhibit, Orlando, Florida , Jan. 4 - 7, 2011.

2 1 Bell, J.H., Heineck, J.T., Zilliac, G, Mehta, R., Long, K.R., "Surface and Flow Field Measurements on the FAITH H ill Model", AIAA 2012 - 704, 50th AIAA Aerospace Sciences, Nashville, Tennessee, January 2011.

2 2 P onomarov, S. Gouterman, M. “ Ideality of Pressure - Sensitive Paint, I. Platinum Tetra(penta - fluorophenyl) P orphine in Fluoroacrylic Polymer ” , Journal of Applied P olymer Science. Vol 77 n 13 , pp. 2795 - 804, 2000 .

2 3 Ruyten, W., “PSP Data Processing: A Manual, Reference Guide, and Tutorial for the AEDC PSP Data Processing Suite”, 24 August 2011.

2 4 http:/ /www.grc.nasa.gov/WWW/wind/valid/plot3D.html , NASA.gov, 15 March 2012.

2 5 Panda, J., Roozeboom, N.H., Ross,J.C., “Evaluation of Unsteady Pres s ure Sensitive Paint Use for Space Launch Vehicle th Buffet Determination”, AIAA 2017 - 1406, 55 AIAA Aerospace Scienc es Meetings, Grapevine, Texas, January 2017.

2 6 Sellers, M.E., Nelson, M., Roozeboom, N.H., Burnside, N., “Evaluation of Unsteady Presure Sensitive Paint Use for Space th Launch Vehicle Buffet Determination” , AIAA 2017 - 1402, 55 AIAA Aerospace Sciences Meetin gs, Grapevine, Texas, January 2017.

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