Fraire Jr. U.,Jacobs Engineering |
Anderson K.,ATK |
AIAA Aerodynamic Decelerator Systems (ADS) Conference 2013 | Year: 2013
The Capsule Parachute Assembly System (CPAS) Project is working to demonstrate the performance of its fully integrated parachute system at higher dynamic pressures and in the presence of wake fields using a Parachute Compartment Drop Test Vehicle (PCDTV) and a Parachute Test Vehicle (PTV), respectively. Simulation of the extraction and separation events has proven challenging and careful modeling of the physics involved is required to reduce the risk of separation malfunctions. The Automatic Dynamic Analysis of Mechanical Systems (ADAMS) program, a Commercial Off-the-Shelf (COTS) multi-body six degree of freedom (DOF) simulator, is employed to model the aircraft extraction and separation maneuvers. ADAMS had been used in similar analyses in the Ares test program and could readily be adapted for use in CPAS analyses. It can model contact forces between test vehicles, a capability that its CPAS predecessor, Decelerator System Simulation Application (DSSA), does not model. Extensive comparisons were made with DSSA to validate the mated portion of the ADAMS extraction trajectory. Results of the comparisons and post-test reconstructions resulted in many modifications that improved the fidelity of the ADAMS Extraction-Separation Model (AESM). ADAMS video animations are overlaid on actual C-12 chase plane test videos to supplement analysis of extraction and separation events. The data-driven architecture of the AESM has proven useful for sensitivity studies, and the simulation has been integrated with NASA simulations to provide end-to-end test trajectories. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. Source
2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010 | Year: 2010
Tapered Periodic Surface (TPS) technology is a very useful building block in the design of ultra broadband antennas. Antennas which employ TPS technology exhibit not only very broad bandwidth, but also low side lobe radiation patterns. TPS exhibits two fundamental properties: l.) Diffraction Control and 2.) Frequency Compensation. © 2010 IEEE. Source
Guery J.-F.,SNPE Materiaux Energetiques |
Chang I.-S.,The Aerospace Corporation |
Shimada T.,Japan Aerospace Exploration Agency |
Boury D.,SNECMA |
And 7 more authors.
Acta Astronautica | Year: 2010
For the last 50 years solid propulsion has successfully created a multitude of small launchers and many first stages or boosters for heavy launchers with low risk, high performance, competitive cost, superb storability, and "instant" readiness in many countries. Technical support for these successes arose from simple designs, very high thrust levels, and low development and operation costs/risks. The first solid propulsion roadmap based on these foundations and rational projections was published in 2000 [A. Davenas, D. Boury, M. Calabro, B. D'Andrea, A. McDonald, Solid propulsion for space applications: a roadmap, in: 51st International Astronautical Congress, paper IAA-00-IAA.3.3.02, October 2000]. Moreover, subsequent information supports its enabling technologies (high strength composite cases, energetic material processing based on continuous mixing, low density insulation, reduced actuator energy requirements, and advanced detailed simulations) and applications (first stages, strap-on, add-ons, small launchers, and niche space applications). Missions currently devoted to solid propulsion and plans for present and future launchers and exploration mission developments in the USA, Japan, and Europe are sketched and targeted improvements, and potential breakthroughs are discussed. © 2009 Elsevier Ltd. All rights reserved. Source
Lawrence R.,Old Dominion University |
Lin B.,NASA |
Harrah S.,NASA |
Hu Y.,NASA |
And 2 more authors.
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2011
The accuracy of numerical weather model predictions of the intensity and track of tropical storms may be significantly improved by large spatial coverage and frequent sampling of sea surface barometry. The availability of a radar operating at moderate-to-strong O2 absorption bands in the frequency range 50~56GHz to remotely measure surface barometric pressure may provide such capability. At these frequencies, the strength of radar echoes from water surfaces has a strong gradient with frequencies owing to the absorption of atmospheric O2. Our recent research has developed a technique based on the use of a dual-frequency, O2-band radar to estimate surface barometric pressure from the measured attenuation due to O2. The ratio of reflected radar signals at multiple wavelengths is used to minimize the effect of microwave absorption by liquid water and water vapor in the atmosphere, and the influences of sea surface reflection over the frequency of operation. A demonstration instrument has been developed to verify the differential O2 absorption measurement approach. Recent test flights to evaluate the in-flight performance of the demonstration instrument have been completed. The measured radar return and differential O2 absorption show good agreement with the modeled results. These flight test results are consistent with our instrumentation goal of ±5mb uncertainty and indicate that our proposed differential absorption measurement approach may provide a useful measurement of sea surface pressure. Future test flights will provide higher altitude data and assess the precision of the sea surface pressure measurement for the existing demonstration radar. © 2010 Elsevier Ltd. Source
News Article | October 14, 2015
The XM25 Counter Defilade Engagement System is about to undergo testing by the U.S. Army, after a successful yet limited run of prototypes of the smart grenade launcher and its airburst grenade in Afghanistan about five years ago. Aerospace and defense firm Oribital ATK developed the XM25. And now the US army has announced its intentions to begin acceptance testing the grenade launch at some point in 2016. Some of the top perks of the smart grenade launcher is its ability to detonate grenades precisely and without impact. Users can limit their exposure during engagements and the splash damage from the airburst grenades can effectively bend corners to reach targets. "The XM25 is a next-generation, semi-automatic weapon designed for effectiveness against enemies protected by walls, dug into foxholes or hidden in hard-to-reach places," says Orbital ATK. The XM25 employs a laser rangefinder that can be used to set precisely when a grenade detonates. Where it detonates is still up to the soldier, though the XM25's fire control system delivers an "adjusted aim point" to help the user exact his or her shot. "The soldier places the adjusted aim point on target and pulls the trigger," says Orbital ATK. "Target information is communicated to the chambered 25 mm round. As the round speeds down range, it measures the distance traveled and bursts at the pre-programmed distance." The XM25 includes 2x direct view optic, 2x thermal sight, a software engine for ballistics, a fuze setter, a display, a digital compass and environmental sensors. It can fire high explosive, nonlethal, flechette, thermobaric and training grenades. Orbital ATK estimates that the fire control system and airburst grenades help improve soldier accuracy by between 300 and 500 percent. The optimum range for the grenade launcher is roughly 1,000 feet, though Orbital ATK says the XM25 is capable of lobbing grenades up to 1,600 feet and beyond. The US Army began field testing the XM25 in November of 2010 in Afghanistan, with a handful of soldiers carrying the smart grenade launchers on patrols. Back then, the XM25 was projected to wrap up approvals and begin issuing a finalized version of the weapons in 2014. While that goal was missed, it may have just been off by a couple of years. See the XM25 in action in the video below.