Measurement and Analysis of Terminal Shock Oscillation and Buffet Forcing Functions on a Launch Vehicle Payload Fairing

The buffet loads on a launch vehicle payload shroud can be impacted by the unsteadiness associated with a terminal shock at high subsonic speeds. At these conditions, flow accelerates to supersonic speeds on the nose of the payload fairing and is terminated by a normal shock on the cylindrical section downstream of the nose cone/cylinder shoulder. The location of the terminal shock and associated separated boundary layer is affected by the freestream Mach number, Reynolds number, and the pitch/yaw of the launch vehicle. Furthermore, even when the freestream conditions and vehicle attitude are constant, this terminal shock oscillates on the surface of the vehicle. The time-varying surface pressure associated with the terminal shock results in unsteady aerodynamic loads that may interact with vehicle structural dynamic modes and the guidance and control of the vehicle. Buffet testing of a 3-percent scale rigid buffet model of a launch vehicle cargo configuration with a tangent-ogive payload shroud was conducted in 2012 and in 2016. Initial buffet forcing functions (BFFs) utilized a coarse pressure sensor distribution on the vehicle surface in which a single longitudinal station with eight sensors observed the terminal shock environment at Mach 0.90. An examination of these circumferential pressures reveal large impulse-like pressure fluctuations and an asymmetry in pressure when the vehicle is at a nonzeroangle of attack that result in high BFFs. Revisions to the shock integration region were made based on computational fluid dynamics and shadowgraph video of shock motion to better represent the BFFs and reduce the high loads resulting from this environment. To more clearly understand this terminal shock environment, a second wind tunnel test was conducted with a dense distribution of 256 sensors at the terminal shock location. These sensor arrays presents a unique opportunity to observe the unsteady terminal shock environment and to characterize the impact of various integration schemes on the BFFs. This paper presents a summary of the development of BFFs for this terminal shock and a detailed analyses of shock region pressure coefficients, coherence, BFFs, shock location time histories, and power spectral density to help guide development of BFFs for other launch vehicle test and analysis programs

Public sector employees volunteer more, and may be able to pave the way to rebuilding social capital in the U.S.

In recent decades many commentators have expressed increasing concern over the apparent decline of civil society in the U.S. Jaclyn Schede Piatak explores one possible way to address this decline, using public sector employees, who, she argues, are more likely to volunteer. She writes that non-profit employees are much more likely to volunteer both formally and informally than those in the for-profit sector, due to their ‘other-orientation’ from their work. With this in mind, public and non-profit workers may be a valuable resource towards beginning to rebuild social capital and civic engagement in the U.S

Assessing Victim Blame: Intersections of Rape Victim Race, Gender, and Ethnicity

The current study sought to assess the impact of the race, gender, and ethnicity of rape victims on college students’ propensity to assign culpability to victims. Using a sample of college students (n=279) from a mid-sized Southeastern university, respondents were given a set of six different vignettes, varying only by victim characteristics. These vignettes featured alcohol-facilitated sexual assault between acquaintances, a common occurrence in college environments. Respondents were asked to evaluate the culpability of the victim through a blameworthiness scale. Through the incorporation of the Illinois Rape Myth Acceptance Scale, this study also measured the respondents’ propensity to assign blame to female rape victims and to alleviate male perpetrators of any responsibility. Results indicated that adherence to rape myth acceptance was a more significant predictor of blameworthiness than victim or respondent characteristics. This exploratory study was designed to add to the growing body of literature examining attitudes toward acquaintance rape

Assessing Victim Blame: Intersections of Rape Victim Race, Gender, and Ethnicity

The current study sought to assess the impact of the race, gender, and ethnicity of rape victims on college students’ propensity to assign culpability to victims. Using a sample of college students (n=279) from a mid-sized Southeastern university, respondents were given a set of six different vignettes, varying only by victim characteristics. These vignettes featured alcohol-facilitated sexual assault between acquaintances, a common occurrence in college environments. Respondents were asked to evaluate the culpability of the victim through a blameworthiness scale. Through the incorporation of the Illinois Rape Myth Acceptance Scale, this study also measured the respondents’ propensity to assign blame to female rape victims and to alleviate male perpetrators of any responsibility. Results indicated that adherence to rape myth acceptance was a more significant predictor of blameworthiness than victim or respondent characteristics. This exploratory study was designed to add to the growing body of literature examining attitudes toward acquaintance rape

WRATS Integrated Data Acquisition System

The Wing and Rotor Aeroelastic Test System (WRATS) data acquisition system (DAS) is a 64-channel data acquisition display and analysis system specifically designed for use with the WRATS 1/5-scale V-22 tiltrotor model of the Bell Osprey. It is the primary data acquisition system for experimental aeroelastic testing of the WRATS model for the purpose of characterizing the aeromechanical and aeroelastic stability of prototype tiltrotor configurations. The WRATS DAS was also used during aeroelastic testing of Bell Helicopter Textron s Quad-Tiltrotor (QTR) design concept, a test which received international attention. The LabVIEW-based design is portable and capable of powering and conditioning over 64 channels of dynamic data at sampling rates up to 1,000 Hz. The system includes a 60-second circular data archive, an integrated model swashplate excitation system, a moving block damping application for calculation of whirl flutter mode subcritical damping, a loads and safety monitor, a pilot-control console display, data analysis capabilities, and instrumentation calibration functions. Three networked computers running custom-designed LabVIEW software acquire data through National Instruments data acquisition hardware. The aeroelastic model (see figure) was tested with the DAS at two facilities at NASA Langley, the Transonic Dynamics Tunnel (TDT) and the Rotorcraft Hover Test Facility (RHTF). Because of the need for seamless transition between testing at these facilities, DAS is portable. The software is capable of harmonic analysis of periodic time history data, Fast Fourier Transform calculations, power spectral density calculations, and on-line calibration of test instrumentation. DAS has a circular buffer archive to ensure critical data is not lost in event of model failure/incident, as well as a sample-and-hold capability for phase-correct time history data

Experimental Data from the Benchmark SuperCritical Wing Wind Tunnel Test on an Oscillating Turntable

The Benchmark SuperCritical Wing (BSCW) wind tunnel model served as a semi-blind testcase for the 2012 AIAA Aeroelastic Prediction Workshop (AePW). The BSCW was chosen as a testcase due to its geometric simplicity and flow physics complexity. The data sets examined include unforced system information and forced pitching oscillations. The aerodynamic challenges presented by this AePW testcase include a strong shock that was observed to be unsteady for even the unforced system cases, shock-induced separation and trailing edge separation. The current paper quantifies these characteristics at the AePW test condition and at a suggested benchmarking test condition. General characteristics of the model's behavior are examined for the entire available data set

Assessment of Buffet Forcing Function Development Process Using Unsteady Pressure Sensitive Paint

A wind tunnel test was conducted at the Ames Unitary Plan Wind Tunnel to characterize the transonic buffet environment of a generic launch vehicle forebody. The test examined a highly instrumented version of the Coe and Nute Model 11 test article first tested in the 1960s. One of the measurement techniques used during this test was unsteady pressure sensitive paint (uPSP) developed at the Arnold Engineering Development Complex. This optical measurement technique measured fluctuating pressures at over 300,000 locations on the surface of the model. The high spatial density of these measurements provided an opportunity to examine in depth the assumptions underpinning the development of buffet forcing functions (BFFs) used in the development of the Space Launch System vehicle. The comparison of discrete-measurement-based BFFs to BFFs developed by continuous surface pressure integration indicates that the current BFF development approach under predicts low frequency content of the BFFs while over predicting high frequency content. Coherence-based adjustments employed to reduce over prediction in the surface integration of discrete pressure measurements contribute to the inaccuracy of the BFFs and their implementation should be reevaluated

Occupational Labor Shortages : Concepts, Causes, Consequences, and Cures

There has long been concern that shortages sometimes develop and persist in specific occupations, leading to inefficiencies in the U.S. economy. This book will help readers understand why occupational shortages arise, how to know a shortage when it is present, and to assess strategies to alleviate the shortage. As the authors show, many economists, including several U.S. Nobel Prize winners, have studied occupational shortages, and this volume builds on their work.https://research.upjohn.org/up_press/1238/thumbnail.jp