Development of a Numeric Predictor-Corrector Aerocapture Guidance for Direct Force Control

Direct force control, where the angle of attack and sideslip angle are modulated, has been proposed as an alternative to bank angle control for aero-assist maneuvers. This paper reimplements the current state-of-the-art aerocapture guidance for bank angle control, Fully Numeric Predictor-corrector Aerocapture Guidance (FNPAG), for direct force control. The optimal control theory underlying the structure of FNPAG is shown to not be applicable to the direct force control approach. Several solution structures for the longitudinal channel are compared by simulating dispersed three-degree-of-freedom trajectories for a reference mission consisting of a low lift-to-drag vehicle and a highly elliptical, 1-sol target orbit around Mars. The equations of motion for the lateral channel are derived, and a controller is designed to target a specified orbital plane. Finally, a Monte Carlo is used to demonstrate the performance of the new guidance

Interview of Noyma Appelbaum, Ed.D.

Noyma Appelbaum was born in 1928 in Philadelphia, Pennsylvania. He was born to immigrant parents, his father being Lithuanian and his mother Ukrainian. Mr. Appelbaum’s parents were politically radical and had involvement in the labor union movement of the early 20th century. His mother, Esther Kaminsky, was involved in the organizing of workers in the textile industries of New York City and Philadelphia. His father, Meyer Appelbaum was pivotal in organizing workers in Philadelphia’s auto industry and, according to the interviewee, was a founding member of Philadelphia’s Communist Party. Noyma Appelbaum was heavily influenced by his parents’ involvement in leftist politics. In his youth he participated in protests and became a member of the Young Pioneers, a youth communist group similar to the Boy Scouts of America in organization but not ideology. He attended Philadelphia schools and eventually went to Temple University with the help of scholarships. During his work there on a journalism degree he worked for the Philadelphia edition of The Daily Worker, a Communist Party supported newspaper. Mr. Appelbaum spent his post college years working in industrial Philadelphia in an attempt to organize factory workers. A major political shift occurred for Mr. Appelbaum in 1956 as Soviet Premier Nikita Khrushchev exposed the atrocities of the heavy handed rule of former Premier Josef Stalin. His disenchantment with communist policies matched that of many Communist Party members. Mr. Appelbaum returned to Temple University in an effort to receive a teaching degree. He goes on to work for many years in Philadelphia area education and eventually works toward his doctorate in education. He and his wife have lived in the East Oak Lane of Philadelphia for over 40 years

Comparison of Aerocapture Performance Using Bank Control and Direct Force Control with Two Human-Scale Vehicles at Mars

Recent studies of human-scale missions to Mars have included a wide trade space of vehicle configurations and control schemes. Some configurations fly at a low angle of attack with a low L/D,while others fly at a high angle of attack with a mid L/D. Some use bank angle control, while others use direct force control, where the angle of attack and sideslip angle are independently modulated. This paper compares the performance of three vehicle configurations: a low-L/D vehicle using direct force control, a low-L/D vehicle using bank control, and a mid-L/D vehicle using bank control. The reference mission is aerocapture at Mars into a highly elliptical, 1-sol orbit. The trajectories are integrated in three degrees of freedom. All three cases utilize numeric predictor-corrector guidances and emulate control system responses with rate and acceleration limits. The configurations are compared using a Monte Carlo analysis. The robustness of each configuration to increased dispersions is also compared

Modal Analysis of a Two-Parachute System

The Orion capsule is designed to land under a nominal configuration of three main parachutes; however, the system is required to be fault tolerant and land successfully if one of the main parachutes fails to open. The Capsule Parachute Assembly System (CPAS) Team performed a series of drop tests in order to characterize the performance of the system with two main parachutes. During the series of drop tests, several distinct dynamical modes were observed. The most consequential of these is the pendulum mode. Three other modes are benign: flyout (scissors), maypole, and breathing. The actual multi-body system is nonlinear, flexible, and possesses significant cross-coupling. Rather than perform analysis of this highly complex system directly, we conduct analysis of each dynamical mode observed during flight, based on first principles. This approach is analogous to traditional aircraft flight dynamics analysis in which the full nonlinear behavior of the airframe is decomposed into longitudinal dynamics (phugoid and short-period modes) and lateral dynamics (spiral, roll-subsidence, and dutch-roll modes). This analysis is intended to supplement multi-body nonlinear simulations in order to provide further insight into the system

Einfluss des Blutungsvolumens auf das postoperative Outcome von Patienten mit spontanen und traumatischen intrakraniellen Blutungen

In der vorliegenden Arbeit wurde das Outcome von 112 Patienten mit intrakranieller Blutung analysiert, um das Blutungsvolumen und die unterschiedliche Dynamik der Blutungen als Einfluss- und prädiktive Faktoren zu korrelieren. 21.4% der 112 eingeschlossenen Patienten hatten ein EDH, 38.4 % ein SDH- bzw. 40.2% ein Intrazerebralhämatom. Die Sub- und Epiduralhämatome waren mehrheitlich traumatische Läsionen, die intrazerebralen Blutungen vorwiegend spontane. Im Gesamtkollektiv hatten 28.6% ein funktionelles, respektive 71.4% ein nicht funktionelles Outcome. Das Ergebnis der 71 traumatischen Blutungen war signifikant besser (38.0% funktionell) als das der 41 spontanen (12.2% funktionell, p=0.004). Bei gleichem Hämatomvolumen haben operativ versorgte spontane Blutungen eine 88% geringere Chance für ein funktionelles Ergebnis als operierte traumatische Blutungen. Im Untersuchungskollektiv wurde der reziproke Zusammenhang von Volumen und GOS sowohl für spontane und traumatische, als auch für akute und subakute Blutungen demonstriert. Nicht signifikant verschieden waren akut und subakut verlaufende Blutungen bezüglich ihres Outcomes (32.8% vs. 23.5% funktionelles Outcome, p= 0.302), und der Volumina (47.5ml vs. 52.8ml, p=0.102)). Der vermutete Zusammenhang zwischen Hämatomgröße und zeitlichem Verlauf konnte damit nicht gezeigt werden. Wir fanden auch keinen signifikanten Unterschied des klinischen Ergebnisses in Bezug auf den chirurgischen Interventionszeitpunkt ( 6h). Bei den traumatischen Hämorrhagien wurde ein Modell mit 3 unabhängigen Faktoren (Alter, initaler GCS und Volumen) zur Prädiktion des Outcomes entwickelt. Kleine Volumina, ein niedriges Alter und ein initial hoher GCS lassen ein funktionelles Outcome vorhersagen. Weitere Faktoren, die jedoch nicht unabhängig mit dem Outcome assoziiert waren, sind Mittellinienverlagerung, initiale Blutglukose, Vorliegen eines Hirnödems und arterielle Hypertonie. Die initiale Glukosekonzentration kann zur Vorhersage des Outcomes nach traumatischen Blutungen beitragen, Als einziger unabhängiger Prädiktor wurde bei den spontanen Raumforderungen die Mittellinienverlagerung ermittelt. Volumen und initiale GCS waren nicht unabhängige Prädiktoren. Das schlechte Outcome nach spontaner Blutung, unabhängig vom Versorgungszeitpunkt, unterstreicht die kontroverse Datenlage bezüglich operativer Therapie dieser Raumforderungen. Traumatische Hämorrhagien in temporaler Lokalisation zeigen ein besseres Ergebnis als vergleichbare lokalisierte spontane Blutungen

A Comparison of Three Algorithms for Orion Drogue Parachute Release

The Orion Multi-Purpose Crew Vehicle is susceptible to ipping apex forward between drogue parachute release and main parachute in ation. A smart drogue release algorithm is required to select a drogue release condition that will not result in an apex forward main parachute deployment. The baseline algorithm is simple and elegant, but does not perform as well as desired in drogue failure cases. A simple modi cation to the baseline algorithm can improve performance, but can also sometimes fail to identify a good release condition. A new algorithm employing simpli ed rotational dynamics and a numeric predictor to minimize a rotational energy metric is proposed. A Monte Carlo analysis of a drogue failure scenario is used to compare the performance of the algorithms. The numeric predictor prevents more of the cases from ipping apex forward, and also results in an improvement in the capsule attitude at main bag extraction. The sensitivity of the numeric predictor to aerodynamic dispersions, errors in the navigated state, and execution rate is investigated, showing little degradation in performance

Linear Analysis of a Two-Parachute System Undergoing Pendulum Motion

Motion resembling that of a pendulum undergoing large-amplitude oscillation was ob- served during a series of flight tests of an unoccupied Orion Capsule Parachute Assembly System (CPAS) drop-test vehicle. Large excursions away from vertical by the capsule could cause it to strike the ground or ocean at a large angle with respect to vertical, with an undesirable attitude with respect to heading, or with a large horizontal or vertical speed. These conditions are to be avoided because they would endanger the occupants of the capsule in an actual mission. Pendulum motion is intimately related to a parachutes aerodynamic normal force coefficient, which is a nonlinear function of angle of attack. An analytical investigation of the dynamics of pendulum motion is undertaken with the aid of a simplified model of the physical system and the assumption that the normal force coefficient is a linear function of angle of attack in the neighborhood of a value corresponding to stable equilibrium. The analysis leads to a simple relationship for the location of a pivot point, which provides insights that are consistent with previous studies