The Helios Prototype vehicle was one of several remotely piloted aircraft funded and developed by NASA under the Environmental Research Aircraft and Sensor Technology (ERAST) project, and managed by NASA's Dryden Flight Research Center (DFRC). This vehicle was a proof-of-concept, propeller-driven, flying wing built and operated by AeroVironment, Inc. The vehicle consisted of two configurations. One configuration, designated HP01, was designed to operate at extremely high altitudes using batteries and high-efficiency solar cells spread across the upper surface of its 247-foot wingspan. On 13 August 2001, this aircraft configuration reached an altitude of 96,863 feet, a world record for sustained horizontal flight by a winged aircraft. The other configuration, designated HP03, was designed for long-duration flight. The plan was to use the solar cells to power the vehicle's electric motors and subsystems during the day and to use a modified commercial hydrogen–air fuel cell system for use during the night. The vehicle was also equipped with batteries as a backup source of power. The aircraft design used wing dihedral, engine power, elevator control surfaces, and a stability augmentation and control system to provide aerodynamic stability and control. On 26 June 2003, HP03-2 took off at 10:06am local time from the Navy's Pacific Missile Range Facility (PMRF) located on the island of Kauai, Hawaii. The aircraft was under the guidance of AeroVironment, Inc. (AV) ground-based mission controllers. At that time the environmental wind conditions appeared to be within an acceptable envelope, and consisted of a wind shadow over and offshore from PMRF, bounded to the north, south, and above by zones of wind shear and turbulence separating this region from the ambient easterly trade-wind flow. However, compared to previous solar-powered flights from PMRF, HP03-2 was subject to longer exposure to the low-level turbulence in the lee of Kauai due to the shallower climb out trajectory. The vehicle's longer exposure to Kauai's lee side turbulence and lower shear line penetration were superposed on what the Board now recognizes as greater airplane sensitivity to turbulence and may have been compounded by the apparent narrow corridor between the shear lines noted by the chase helicopter observer. At 10:22am and 10:24am, the aircraft encountered turbulence and the wing dihedral became much larger than normal and mild pitch oscillations began, but quickly damped out. At about 30 minutes into the flight, the aircraft encountered turbulence and morphed into an unexpected, persistent, high dihedral configuration. As a result of the persistent high dihedral, the aircraft became unstable in a very divergent pitch mode in which the airspeed excursions from the nominal flight speed about doubled every cycle of the oscillation. The aircraft's design airspeed was subsequently exceeded and the resulting high dynamic pressures caused the wing leading edge secondary structure on the outer wing panels to fail and the solar cells and skin on the upper surface of the wing to rip off. The aircraft impacted the ocean within the confines of the PMRF test range and was destroyed. The crash caused no other property damage or any injuries to personnel on the ground. Most of the vehicle structure was recovered except the hydrogen-air fuel cell pod and two of the ten engines, which sank into the ocean. The root causes of the mishap include: Lack of adequate analysis methods led to an inaccurate risk assessment of the effects of configuration changes leading to an inappropriate decision to fly an aircraft configuration highly sensitive to disturbances, and Configuration changes to the aircraft, driven by programmatic and technological constraints, altered the aircraft from a spanloader to a highly point-loaded mass distribution on the same structure significantly reducing design robustness and margins of safety.
Brooklyn’s Hasidic community of Lubavitchers is turned upside down when family tragedy strikes and everyday life changes forever in the life of Zev Altshul. He is first placed into the care of the closed and close-knit community where he grew up, but soon realizes he can’t stay. His saving grace is handball; it’s his gift from God, and the one thing he can rely on as he is shuttled, chased, and abandoned by trusted elders, family, and friends. Even as Zev never fully escapes from the guilt of his choices, he sets course across the United States to discover where loyalty really lies and what it means. He seeks out his long-lost sister, only to find himself as unprepared for life outside the Lubavitcher community as he was unwilling to remain. Forced out of his second home, Zev plays handball to support himself in the goyische world, but obligations he doesn’t fully understand still tie him to Crown Heights and follow him to Chicago and New Mexico threatening always to return Zev to life among the Lubavitchers. Lyrical, vivid, and thoroughly engaging, this is certainly among the first novels of its kind.
Articles fundamental to the study of warfare in England and Normandy in the 11th and 12th centuries collected here in one volume. The influence of war on late Anglo-Saxon and Anglo-Norman society was dominant and all-pervasive. Here in this book, gathered together for the first time, are fundamental articles on warfare in England and Normandy in the 11th and12th centuries, combining the work of some of the foremost scholars in the field. Redressing the tendency to study military institutions and obligations in isolation from the practice of war, equal emphasis is given both to organisation and composition of forces, and to strategy, tactics and conduct of war. The result is not only an in-depth analysis of the nature of war itself, but a study of warfare in a broader social, political and cultural context. The Themes dealt with largely span the period of the Conquest, offering an assessment of the extent to which the Norman invasion marked radical change or a degree of continuity in the composition of armies and in methods offighting. This important collection, with an introduction and select bibliography, will be is essential not simply for the student of medieval warfare, but for all studying Anglo-Norman society and its ruling warrior aristocracy whose raison d'être was war. Contributors: NICHOLAS HOOPER, MARJORIE CHIBNALL, J.C. HOLT, J.O. PRESTWICH, R. ALLEN BROWN, JOHN GILLINGHAM, JIM BRADBURY, MATTHEW STRICKLAND, MATTHEW BENNETT.
This book examines the origin, content, and development of the musical thought of Heinrich Schenker and Arnold Schoenberg. One of the premises is that Schenker’s and Schoenberg’s inner musical lives are inseparable from their inner spiritual lives. Curiously, Schenker and Schoenberg start out in much the same musical-spiritual place, yet musically they split while spiritually they grow closer. The reception of Schenker’s and Schoenberg’s work has sidestepped this paradox of commonality and conflict, instead choosing to universalize and amplify their conflict. Bringing to light a trove of unpublished material, Arndt argues that Schenker’s and Schoenberg’s conflict is a reflection of tensions within their musical and spiritual ideas. They share a particular conception of the tone as an ideal sound realized in the spiritual eye of the genius. The tensions inherent in this largely psychological and material notion of the tone and this largely metaphysical notion of the genius shape both their musical divergence on the logical (technical) level in theory and composition, including their advocacy of the Ursatz versus twelvetone composition, and their spiritual convergence, including their embrace of Judaism. These findings shed new light on the musical and philosophical worlds of Schenker and Schoenberg and on the profound artistic and spiritual questions with which they grapple.
Thank you for visiting our website. Would you like to provide feedback on how we could improve your experience?
This site does not use any third party cookies with one exception — it uses cookies from Google to deliver its services and to analyze traffic.Learn More.