90 research outputs found
James Ira Grimsley to Governor Ross Barnett, 20 September 1962
Grimsley congratulates Barnett on his stand and states that the sheriff\u27s department of Jackson County supports him.https://egrove.olemiss.edu/west_union_gov/1015/thumbnail.jp
Regulating Drones Under the First and Fourth Amendments
The FAA Modernization and Reform Act of 2012 requires the Federal Aviation Administration to integrate unmanned aerial vehicles (UAVs), or drones, into the national airspace system by September 2015. Yet perhaps because of their chilling accuracy in targeted killings abroad, perhaps because of an increasing consciousness of diminishing privacy more generally, and perhaps simply because of a fear of the unknown, divergent UAV-restrictive legislation has been proposed in Congress and enacted in a number of states. Given UAV utility and cost-effectiveness over a vast range of tasks, however, widespread commercial use ultimately seems certain. Consequently, it is imperative to understand the constitutional restraints on public flight and constitutional protections afforded to private flight. Unfortunately, although there are a few Fourth Amendment precedents in manned aviation, they are mired not only in 1980s technology but also in the 1980s third party doctrine, and therefore do not reflect more recent Fourth Amendment developments and doctrinal fissures. There is also considerable uncertainty over First Amendment protection of information-gathering—for example, is there a right to record? Further, there is no judicial or scholarly analysis of how UAV flight fits within contemporary First Amendment forum doctrine, a framework that provides a useful starting point for analyzing speech restrictions in government-controlled airspace, but that comes with some uncertainties of its own. It is into this thicket that we dive, and fortunately some clarity emerges. Although the Fourth Amendment third party doctrine hopelessly misunderstands privacy and therefore under-protects our security and liberty interests, the Supreme Court’s manned flyover cases can be mined for a sensible public disclosure doctrine that seems agnostic as to the various Fourth Amendment conceptions: we do not typically require only law enforcement to shield its eyes. Of course, both constitutions and legislation can place special restrictions upon law enforcement, and sometimes doing so makes good sense. But as a general Fourth Amendment matter, the officer may do and see as the citizen would. Hence to understand Fourth Amendment regulation, we must understand how the First Amendment limits government restraint on speech-relevant private UAV flight. Here we analyze the developing right to record and apply contemporary forum doctrine to this novel means of speech and information-gathering. If navigable airspace is treated as a limited public forum, as we propose with some qualification, then the Federal Aviation Administration will have significant—though not unlimited—regulatory leeway to evenhandedly burden speech-related UAV activities where doing so would reasonably promote safe unmanned and manned flight operations. The Agency, however, would likely need further congressional action before it can restrict UAV flight based on privacy rather than safety concerns. As the legality and norms of private flight correspondingly take shape, they will inform Fourth Amendment restrictions on government use
Elevated Temperature, Notched Compression Performance of Out of Autoclave Processed Composites
Curved honeycomb sandwich panels composed of carbon fiber reinforced toughened-epoxy polymer facesheets are being evaluated for potential use as payload fairing components on the NASA heavy-lift space launch system (HL-SLS). These proposed composite sandwich panels provide the most efficient aerospace launch structures, and offer mass and thermal advantages when compared with existing metallic payload fairing structures. NASA and industry are investigating recently developed carbon fiber epoxy prepreg systems which can be fabricated using out-of autoclave (OOA) processes. Specifically, OOA processes using vacuum pressure in an oven and thereby significantly reducing the cost associated with manufacturing large (up to 10 m diameter) composite structures when compared with autoclave. One of these OOA composite material systems, CYCOM(R) 5320-1, was selected for manufacture of a 1/16th scale barrel portion of the payload fairing; such that, the system could be compared with the well-characterized prepreg system, CYCOM(R) 977-3, typically processed in an autoclave. Notched compression coupons for each material were obtained from the minimum-gauge flat laminate [60/-60/0]S witness panels produced in this manufacturing study. The coupons were also conditioned to an effective moisture equilibrium point and tested according to ASTM D6484M-09 at temperatures ranging from 25 C up to 177 C. The results of this elevated temperature mechanical characterization study demonstrate that, for thin coupons, the OHC strength of the OOA laminate was equivalent to the flight certified autoclave processed composite laminates; the limitations on the elevated temperature range are hot-wet conditions up to 163 C and are only within the margins of testing error. At 25 C, both the wet and dry OOA material coupons demonstrated greater OHC failure strengths than the autoclave processed material laminates. These results indicate a substantial improvement in OOA material development and processing since previous studies have consistently reported OOA material strengths on par or below those of autoclave processed composite laminates
Paper Session II-A - Polyimide Foam Insulation Materials for Aerospace Vehicles and Spaceport Applications
Advancements in high temperature materials by NASA have led to the development of polyimide foam systems with very attractive properties. The properties generated demonstrate the suitability of these materials for use as insulation for cryogenic fuel tanks on next generation vehicles, commercial and military ships, and potentially commercial aircraft. The significance of structural polyimide foams can be realized with a reduction in the overall weight of a launch vehicle. Due to a polyimide\u27 s high operating temperature ( \u27 \u27 260°C) structural polyimide foams can potentially reduce the amount of Thermal Protection System (TPS) and TPS integration structure that is required on launch vehicles. The lowtemperature elasticity of other polyimide foams is an enabling feature for many new cryogenic applications. These high performance materials also have properties that fulfill the demanding upcoming needs in ground support equipment for a Spaceport Technology Center.
In a research study performed by Kennedy Space Center (KSC) and Langley Research Center (LaRC), polyimide foams were investigated for their physical, mechanical, thermal, and flammability properties. Variations in chemical structure, cell surface area, cell content and density on the resultant physical properties of the foams were studied. Data generated from this research revealed vital information involving foam technology and the interplay of factors such as foam density, open-closed cell content, surface area, and cell structure on the overall performance of the material. By controlling these parameters, new thermal insulation systems based on polyimide foam materials can be designed to meet demanding applications for spaceports and space vehicles
Properties of Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Matrix Composites
For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strength- and stiffness-to-weight ratios, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Carbon nanotubes (CNT) offer the potential to enhance the multi-functionality of composites with improved thermal and electrical conductivity. In this study, hybrid CNT/carbon fiber (CF) polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing. Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated
Elevated Temperature, Residual Compressive Strength of Impact-Damaged Sandwich Structure Manufactured Out-of-Autoclave
Several 1/16th-scale curved sandwich composite panel sections of a 10 m diameter barrel were fabricated to demonstrate the manufacturability of large-scale curved sections using minimum gauge, [+60/-60/0]s, toughened epoxy composite facesheets co-cured with low density (50 kilograms per cubic meters) aluminum honeycomb core. One of these panels was fabricated out of autoclave (OoA) by the vacuum bag oven (VBO) process using Cycom(Registered Trademark) T40-800b/5320-1 prepreg system while another panel with the same lay-up and dimensions was fabricated using the autoclave-cure, toughened epoxy prepreg system Cycom(Registered Trademark) IM7/977-3. The resulting 2.44 m x 2 m curved panels were investigated by non-destructive evaluation (NDE) at NASA Langley Research Center (NASA LaRC) to determine initial fabrication quality and then cut into smaller coupons for elevated temperature wet (ETW) mechanical property characterization. Mechanical property characterization of the sandwich coupons was conducted including edge-wise compression (EWC), and compression-after-impact (CAI) at conditions ranging from 25 C/dry to 150 C/wet. The details and results of this characterization effort are presented in this paper
Thermal Properties of Hybrid Carbon Nanotube/Carbon Fiber Polymer
Carbon fiber reinforced polymer (CFRP) composites possess many advantages for aircraft structures over conventional aluminum alloys: light weight, higher strength- and stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low thermal and electrical conductivities of CFRP composites are deficient in providing structural safety under certain operational conditions such as lightning strikes. One possible solution to these issues is to interleave carbon nanotube (CNT) sheets between conventional carbon fiber (CF) composite layers. However, the thermal and electrical properties of the orthotropic hybrid CNT/CF composites have not been fully understood. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel (Registered Trademark) IM7/8852 prepreg. The CNT sheets were infused with a 5% solution of a compatible epoxy resin prior to composite fabrication. Orthotropic thermal and electrical conductivities of the hybrid polymer composites were evaluated. The interleaved CNT sheets improved the in-plane thermal conductivity of the hybrid composite laminates by about 400% and the electrical conductivity by about 3 orders of magnitude
Fracture Toughness of Carbon Fiber Composites Containing Various Fiber Sizings and a Puncture Self-Healing Thermoplastic Matrix
Ongoing efforts at NASA Langley Research Center (LaRC) have resulted in the identification of several commercially available thermoplastic resin systems which self-heal after ballistic impact and through penetration. One of these resins, polybutylene graft copolymer (PBg), was selected as a matrix for processing with unsized carbon fibers to fabricate reinforced composites for further evaluation. During process development, data from thermo-physical analyses was utilized to determine a processing cycle to fabricate laminate panels, which were analyzed by photo microscopy and acid digestion. The process cycle was further optimized based on these results to fabricate panels for mechanical property characterization. The results of the processing development effort of this composite material, as well as the results of the mechanical property characterization, indicated that bonding between the fiber and PBg was not adequate. Therefore, three sizings were investigated in this work to assess their potential to improve fiber/matrix bonding compared to previously tested unsized IM7 fiber. Unidirectional prepreg was made at NASA LaRC from three sized carbon fibers and utilized to fabricate test coupons that were tested in double cantilever beam configurations to determine GIc fracture toughness
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