Design and Evaluation of Dual-Expander Aerospike Nozzle Upper Stage Engine

The goal of the Dual-Expander Aerospike Nozzle, a modification to traditional engine architectures, is to find those missions and designs for which it has a competitive advantage over traditional upper stage engines such as the RL10. Previous work focused on developing an initial design to demonstrate the feasibility of the Dual-Expander Aerospike Nozzle. This research expanded the original cycle model in preparation for optimizing the engine\u27s specific impulse and thrust-to-weight ratio. The changes to the model allowed automated parametric and optimization studies. Preliminary parametric studies varying oxidizer-to-fuel ratio, total mass flow, and chamber length showed significant improvements. Drawing on modeling lessons from previous research, this research developed a new engine simulation capable of achieving a specific impulse comparable to the RL10. Parametric studies using the new model verified the Dual-Expander Aerospike Nozzle architecture conforms to rocket engine theory while exceeding the RL10\u27s performance. Finally, this research concluded by optimizing the Dual-Expander Aerospike Nozzle engine for three US government missions: the Next Generation Engine program, the X-37 mission, and the Space Launch System. The optimized Next Generation Engine design delivers 35,000 lbf of vacuum thrust at 469.4 seconds of vacuum specific impulse with a thrust-to-weight ratio of 127.2 in an engine that is one quarter the size of a comparable RL10. For the X-37 mission, the optimized design operates at 6,600 lbf of vacuum thrust and has a vacuum specific impulse of 457.2 seconds with a thrust-to-weight ratio of 107.5. The Space Launch System design produces a vacuum thrust of 100,000 lbf with a vacuum specific impulse of 465.9 seconds and a thrust-to-weight ratio of 110.2. When configured in a cluster of three engines, the Dual-Expander Aerospike Nozzle matches the J2-X vacuum thrust with a 4% increase in specific impulse

Design and Evaluation of Dual-Expander Aerospike Nozzle Upper Stage Engine

The goal of the Dual-Expander Aerospike Nozzle, a modification to traditional engine architectures, is to find those missions and designs for which it has a competitive advantage over traditional upper stage engines such as the RL10. Previous work focused on developing an initial design to demonstrate the feasibility of the Dual-Expander Aerospike Nozzle. This research expanded the original cycle model in preparation for optimizing the engine\u27s specific impulse and thrust-to-weight ratio. The changes to the model allowed automated parametric and optimization studies. Preliminary parametric studies varying oxidizer-to-fuel ratio, total mass flow, and chamber length showed significant improvements. Drawing on modeling lessons from previous research, this research developed a new engine simulation capable of achieving a specific impulse comparable to the RL10. Parametric studies using the new model verified the Dual-Expander Aerospike Nozzle architecture conforms to rocket engine theory while exceeding the RL10\u27s performance. Finally, this research concluded by optimizing the Dual-Expander Aerospike Nozzle engine for three US government missions: the Next Generation Engine program, the X-37 mission, and the Space Launch System. The optimized Next Generation Engine design delivers 35,000 lbf of vacuum thrust at 469.4 seconds of vacuum specific impulse with a thrust-to-weight ratio of 127.2 in an engine that is one quarter the size of a comparable RL10. For the X-37 mission, the optimized design operates at 6,600 lbf of vacuum thrust and has a vacuum specific impulse of 457.2 seconds with a thrust-to-weight ratio of 107.5. The Space Launch System design produces a vacuum thrust of 100,000 lbf with a vacuum specific impulse of 465.9 seconds and a thrust-to-weight ratio of 110.2. When configured in a cluster of three engines, the Dual-Expander Aerospike Nozzle matches the J2-X vacuum thrust with a 4% increase in specific impulse

Aeroelastic Optimization of Sounding Rocket Fins

This research effort develops a multidisciplinary design tool to optimize sounding rocket fin geometries that minimize the mass of the fins while maintaining aerodynamic performance. This research grew out of a design problem experienced by the US Air Force Academy\u27s Falcon LAUNCH program. The Falcon LAUNCH program is a senior design capstone project during which Air Force Academy cadets design, build and fly a sounding rocket over the course of an academic year. In the Spring of 2007, the Falcon LAUNCH V vehicle experienced a catastrophic failure when three of its four fins sheared off due to flutter. When the following year\u27s team developed the fins for Falcon LAUNCH VI, the design requirement that the fins not experience flutter led to substantially more massive fins. The Falcon LAUNCH team needs a design tool that can balance the competing needs for minimal mass sounding rocket components and aerodynamic performance. The tool developed during this research is designed to find an optimal solution for the fin geometry based on the competing needs of minimizing the fins\u27 mass and ensuring the fins will not experience flutter. The design tool then provides for verification of the design throughout the designed flight profile

Precision Electroweak Constraints on Hidden Local Symmetries

In this talk we discuss the phenomenology of models with replicated electroweak gauge symmetries, based on a framework with the gauge structure [SU(2) or U(1)] x U(1) x SU(2) x SU(2).Comment: 7 pages, talk given at SCGT0

Aerospike Rockets for Increased Space Launch Capability

The US Department of Defense DOD increasingly depends on space assets for everyday operations. Precision navigation communications and intelligence, surveillance, and reconnaissance satellites are highly leveraged space assets. The launch vehicles that place these satellites in orbit are a major limitation of current space systems. If higher-performing launch vehicles were available, many satellites could accommodate additional capabilities, whether in terms of more sensor channels, types of payloads, electrical power, or propellant for orbital maneuvering and station keeping. Space assets are typically designed to conform to a particular launch vehicle s limitations e.g., engineers might design a satellite to be carried by a Delta IV-2 medium launch vehicle. Essentially, this choice of vehicle fixes the maximum mass of the satellite and, thus, its capabilities. If a launcher capable of placing more mass in the desired orbit were available at similar cost, the satellite s design could allow for additional capability. Furthermore, some payloads are too heavy for present-day launch vehicles to place into a particular orbit. A better-performing launcher would enable us to put those payloads into the desired orbits, permitting new missions and capabilities

A controlled study of virtual reality in first-year magnetostatics

Stereoscopic virtual reality (VR) has experienced a resurgence due to flagship products such as the Oculus Rift, HTC Vive and smartphone-based VR solutions like Google Cardboard. This is causing the question to resurface: how can stereoscopic VR be useful in instruction, if at all, and what are the pedagogical best practices for its use? To address this, and to continue our work in this sphere, we performed a study of 289 introductory physics students who were sorted into three different treatment types: stereoscopic virtual reality, WebGL simulation, and static 2D images, each designed to provide information about magnetic fields and forces. Students were assessed using preliminary items designed to focus on heavily-3D systems. We report on assessment reliability, and on student performance. Overall, we find that students who used VR did not significantly outperform students using other treatment types. There were significant differences between sexes, as other studies have noted. Dependence on students' self-reported 3D videogame play was observed, in keeping with previous studies, but this dependence was not restricted to the VR treatment.Comment: 6 pages, 4 figures, submitted to the 2019 Physics Education Research Conferenc

X-Ray and UV Orbital Phase Dependence in LMC X-3

The black-hole binary LMC X-3 is known to be variable on time scales of days to years. We investigate X-ray and ultraviolet variability in the system as a function of the 1.7 day binary phase using a 6.4 day observation with the Rossi X-ray Timing Explorer (RXTE) from December 1998. An abrupt 14% flux decrease, lasting nearly an entire orbit, is followed by a return to previous flux levels. This behavior occurs twice, at nearly the same binary phase, but it is not present in consecutive orbits. When the X-ray flux is at lower intensity, a periodic amplitude modulation of 7% is evident in data folded modulo the orbital period. The higher intensity data show weaker correlation with phase. This is the first report of X-ray variability at the orbital period of LMC X-3. Archival RXTE observations of LMC X--3 during a high flux state in December 1996 show similar phase dependence. An ultraviolet light curve obtained with the High Speed Photometer aboard the Hubble Space Telescope shows orbital modulation consistent with that in the optical, caused by the ellipsoidal variation of the spatially deformed companion. The X-ray spectrum of LMC X-3 can be acceptably represented by a phenomenological disk-black-body plus a power law. Changes in the spectrum of LMC X-3 during our observations are compatible with earlier observations during which variations in the 2-10 keV flux are tracked closely by the disk geometry spectral model parameter.Comment: 11 pages, 7 figures, ApJ in pres

Prospectus, September 9, 2004

https://spark.parkland.edu/prospectus_2004/1018/thumbnail.jp

Looking our limitations in the eye: A call for more thorough and honest reporting of study limitations

The replication crisis and subsequent credibility revolution in psychology have highlighted many suboptimal research practices such as p‐hacking, overgeneralizing, and a lack of transparency. These practices may have been employed reflexively but upon reflection, they are hard to defend. We suggest that current practices for reporting and discussing study limitations are another example of an area where there is much room for improvement. In this article, we call for more rigorous reporting of study limitations in social and personality psychology articles, and we offer advice for how to do this. We recommend that authors consider what the best argument is against their conclusions (which we call the “steel‐person principle”). We consider limitations as threats to construct, internal, external, and statistical conclusion validity (Shadish et al., 2002), and offer some examples for better practice reporting of common study limitations. Our advice has its own limitations — both our representation of current practices and our recommendations are largely based on our own metaresearch and opinions. Nevertheless, we hope that we can prompt researchers to write more deeply and clearly about the limitations of their research, and to hold each other to higher standards when reviewing each other's work