Search Results

The 2018 Ultimate GD&T Pocket Guide explains the most common rules, symbols, and concepts used in geometric dimensioning and tolerancing. This one-of-a-kind reference guide includes more than 100 detailed examples to illustrate concepts. Numerous charts for quick reference provide explanations of each GD&T symbol, modifier, and more. This valuable on-the-job resource clarifies how to interpret standard-compliant technical drawings that use ASME Y14.5-2018.

Aircraft potable (drinking) water systems haven’t changed significantly in the last half-century. These systems consist of cylindrical water tanks pressurized by bleed air from the jet engines, with insulated stainless steel distribution lines. What has changed recently is the increase in the possibility of aircraft picking up contaminated drinking water at foreign and domestic stops. Customer awareness of these problems has also changed - to the point where having reliable drinking water is now a competitive issue among airlines. Old style potable water systems that are used on modern aircraft are high maintenance and exacerbate the growth of microbes because the water is static much of the time. The integrity of some pressurized water tanks are also a concern after years of use. Cost-effective mechanical and biological solutions exist that can significantly reduce the amount of chemicals added and provide good potable water.

Ultrasound is attractive for medical imaging in space because scanners can be small, lightweight, low power, and have minimal electromagnetic emissions. In addition, unlike conventional 2-D ultrasound. 3-D ultrasound allows an operator with no diagnostic skills to collect high-quality scans that can be interpreted by a remote expert. This allows 3-D ultrasound to be used effectively in remote locations. These capabilities are illustrated by the MUSTPAC-1, a portable 3-D ultrasound telemedicine system recently developed for the U.S. military. Design, implementation, and field experiences with the MUSTPAC-1 are discussed, and extensions for use in space are proposed.

A lightning mapping system has been developed that locates the sources of VHF radiation from lightning discharges in three spatial dimensions and time. The system consists of several VHF receivers distributed over an area of about 100 km diameter. The system locates VHF radiation sources over the array with an accuracy of about 100 m. The system locates sources out to 250 km from the center of the array with reduced accuracy. The observations are found to reflect the basic charge structure of electrified storms.

The need to improve quality while reducing cost in aerospace manufacturing is requiring new manufacturing methods and processes. Advanced technologies, such as 3D Image Metrology, offer great potential to lean manufacturing, if properly integrated into the production process. Over the last years 3D Image Metrology has developed a level of performance, which make it ideally suited for this purpose. These capabilities include the automatic in-process inspection of tools and parts before machining, machine control for highly accurate positioning during the machining operation, and in-process inspection during machining. This offers jig-less assembly, lower inventory, faster part throughput, and many more advantages.

In CFD (Computational Fluid Dynamics) verification of vehicle aerodynamics, detailed velocity measurements are required. The conventional 2D-PIV (Two Dimensional Particle Image Velocimetry) needs at least twice the number of operations to measure the three components of velocity ( u,v,w ), thus it is difficult to set up precise measurement positions. Furthermore, there are some areas where measurements are rendered impossible due to the relative position of the object and the optical system. That is why the acquisition of detailed velocity data around a vehicle has not yet been attained. In this study, a detailed velocity measurement was conducted using a 3D-PIV measurement system. The measurement target was a quarter scale SAE standard vehicle model. The wind tunnel system which was also designed for a quarter scale car model was utilized. It consisted of a moving belt and a boundary suction system.

Abstract Additive manufacturing (AM) technologies can produce lighter parts; reduce manual assembly processes; reduce the number of production steps; shorten the production cycle; significantly reduce material consumption; enable the production of prostheses, implants, and artificial organs; and produce end-user products since it is used in many sectors for many reasons; it has also started to be used widely, especially in the field of aerospace. In this study, polylactic acid (PLA) was preferred for the antenna substrate because it is environmentally friendly, easy to recycle, provides convenience in production design with a three-dimensional (3D) printer, and is less expensive compared to other available materials. Copper (Cu) tape and graphene filament were employed for the antenna patch component due to their benefits.

The 94 GHz MMW airborne radar system that provides a runway image in adverse weather conditions is now undergoing tests at Wright-Patterson Air Force Base (WPAFB). This system, which consists of a solid state FMCW transceiver, antenna and digital signal processor, has an update rate of 10 times per second, 0.35° azimuth resolution and up to 3.5 meter range resolution. The radar B scope (range versus azimuth) image, once converted to C scope (elevation versus azimuth), is compatible with the standard TV presentation and can be displayed on the Head Up Display (HUD) or Head Down Display (HDD) to aid the pilot during landing and takeoff in limited visibility conditions.

The Near Infrared Camera and Multi Object Spectrometer (NICMOS) was installed in the Hubble Space Telescope in February 1997. Shortly thereafter, the instrument experienced a thermal short in its solid nitrogen dewar system which will shorten its useful life significantly. A reverse Brayton cycle mechanical refrigerator will be installed during the third servicing mission (SM3) to provide cooling for the instrument, and thereby extend its life. A Capillary Pump Loop (CPL) and radiator system has been designed, built and tested to remove up to 500 watts of heat from the mechanical cooler and its electronics. This paper will describe the CPL system in detail and present the results of the extensive testing and qualification program.

The Hubble Space Telescope (HST) was designed to be serviced from the shuttle by astronauts performing extravehicular activities (EVA). During the first HST Servicing Mission (STS-61) two types of power tools were flown, the Power Ratchet Tool (PRT) and the HST Power Tool. Each tool had both benefits and drawbacks. An objective for the second HST servicing mission was to combine the reliability, accuracy, and programmability of the PRT with the pistol grip ergonomics and compactness of the HST Power Tool into a new tool called the EVA Pistol Grip Tool (PGT). The PGT is a self-contained, microprocessor controlled, battery powered, 3/8-inch drive hand-held tool. The PGT may also be used as a non-powered ratchet wrench. Numerous torque, speed, and turn or angle limits can be programmed into the PGT for use during various servicing missions. Batteries Modules are replaceable during ground, Intravehicular Activities (IVA), and EVA operations.

The future of human exploration in the solar system is contingent on the ability to exploit resources in-situ to produce mission consumables. Specifically, it has become clear that the success of a manned mission to Mars will likely depend on fuel components created on the Martian surface. While several architectures for an unmanned fuel production surface facility on Mars exist in theory, a simulation of the performance and operation of these architectures has not been created. In this paper, the framework describing a simulation of one such architecture is defined. Within this architecture, each component of the base is implemented as a state machine, with the ability to communicate with other base elements as well as a supervisor. An environment supervisor is also created which governs low level aspects of the simulation such as movement and resource distribution, in addition to higher-level aspects such as location selection with respect to operations specific behavior.

A new method of analyzing the kinematics of joint motion is developed in this study. Magnetic Resonance Imaging (MRI) offers several distinct advantages. Past methods of studying anatomic joint motion have usually centered on four approaches. These methods are x-ray projection, goniometric linkage analysis, sonic digitization, and landmark measurement of photogrammetry. Of these four, only x-ray is applicable for in vivo studies. The remaining three methods utilize other types of projections of inter-joint measurements, which can cause various types of error. MRI offers accuracy in measurement due to its tomographic nature (as opposed to projection) without the problems associated with x-ray dosage. Once the data acquisition of MR images was complete, the images for this study were processed using a 3-D volume rendering workstation. In this study, the metacarpalphalangeal (MCP) joint of the left index finger was selected and reconstructed into a three-dimensional graphic display.

The objective of this work is to better understand freezing fog/drizzle conditions using observations collected during the Fog Remote Sensing and Modeling project (FRAM-S) that took place at St. John's International Airport, St. John's, NL, Canada. This location was ~1 km away from the Atlantic Ocean coast. During the project, the following measurements at one minute resolution were collected: precipitation rate (PR) and amount, fog/drizzle microphysics, 3D wind speed (Uh) and turbulence (Uh'), visibility (Vis), IR and SW radiative fluxes, temperature (T) and relative humidity (RH), and aerosol observations. The reflectivity and microphysical parameters obtained from the Metek Inc. MRR (Microwave Rain Radar) were also used in the analysis. The measurements were then used to obtain freezing fog/drizzle microphysical characteristics and their relation to visibility.

The quantification of aircraft survivability in modern battlefield environments is a complex mathematical problem. In general, consideration must be given to the quantification of aircraft vulnerability to individual weapon systems, single encounter aircraft survivability, and the mathematical mapping of single encounter aircraft survivability into mission attrition. A methodology for quantifying the impacts of electronic warfare (EW) upon aircraft survivability is realized by the General Effectiveness Methodology (GEM) which is based upon a hierarchy of computer models. This paper describes this hierarchy of computer simulation tools which extensively employs probability theory to estimate the various engagement events such as aircraft detection, acquisition, missile launch, missile intercept, and probability of aircraft kill.

This paper describes a model-based tool for analyzing the activities of glass cockpit flight crews. The tool is based on the Crew Activity Tracking System (CATS). CATS has been extended to provide visualization and data playback capabilities to support analysis of pilot-automation interaction. Use of the tool for analyzing high fidelity flight simulator data from a NASA Air Traffic Management simulation as part of a model-based design process is described.

Over the last few years, many aircraft production lines have seen their production rate increase. In some cases, to avoid bottlenecks in the assembly lines, the productivity of processes needs to be improved while keeping existing machine-tools. In this context, the case of drilling machine-tools tends to require particular attention, especially when multi-material parts are drilled. In such instances, the Vibration Assisted Drilling (VAD) process can be a way to improve productivity and reliability while keeping quality standards. This article presents a case of a drilling/countersinking process for stainless steel and titanium stack parts. Firstly, the article assesses the feasibility and benefits of using Vibration Assisted Drilling and Countersinking with the current cutting-tools. Secondly, it studies the consequences of introducing a new tool holder in the process, which combines the V.A.D. function, a new declutching function and the ability to control countersink depth.

The Far Infrared and Submillimetre Space Telescope is one of ESA's cornerstone missions in the “horizon 2000” programme. One option to cool the scientific instruments of this satellite is a superfluid helium (He II) cryostat. A trade-off analysis was performed about different sizes and configurations of a cryostat such as to meet the operational lifetime requirement of 2 - 4 years on either a highly elliptical 24 hours orbit or on a far-away from earth orbit. The possible size alternatives for a cryostat using to a maximum extent existing ISO-technology are presented. Upon ESA-decision a final cryostat size for the 24 hours orbit which provides at least 3 years operational lifetime was selected. This cryostat is described and presented.

An advanced development helmet mounted display (HMD) was designed and fabricated under NASA-Johnson Space Center (NASA/JSC) contract, NAS 9-17543, by Hamilton Standard Division of United Technologies, Windsor Locks, CT. The work was initiated in December 1985 and culminated in June 1988 with the delivery of an extravehicular mobility unit (EMU) HMD demonstration unit as an alternative to the current low-resolution, chest-mounted display and cuff-mounted checklists. Important design goals achieved with this HMD include the use of transmissive liquid crystal display (LCD) image sources with fairly high resolution (i.e., text, graphics, and video compatible), binocular viewing with total image overlap, virtual image projection, low profile packaging, low power design, and demonstration of voice control of the HMD data.

The AV-8B Harrier II V/STOL strike aircraft for the U.S. Marine Corps features an advanced design, limited authority digital Stability Augmentation and Attitude Hold System (SAAHS). Utilization of this single channel electronic flight control system required an extensive self-test and monitoring system. New techniques to detect failures were based on extensive simulation, Iron Bird and flight test results. Self-test capabilities are provided for maintainability as well as safety. SAAHS monitoring is implemented in three primary categories: hardware, software monitor of hardware, and software monitor of performance. Total system health is determined in a comprehensive preflight Built-in-Test (BIT). System performance during flight is continuously monitored by In-Flight-Monitoring (IFM).

Heat pipes, loop heat pipes and capillary pumped loops are heat transfer devices driven by capillary forces with high-effectiveness & performance, offering high-reliability & flexibility in varying g-environments. They are suitable for spacecraft thermal control where the mass, volume, and power budgets are very limited. The Canadian Space Agency is developing loop heat pipe hardware aimed at understanding the thermal performance of two-phase heat transfer devices and in developing numerical simulation techniques using thermo-hydraulic mathematical models, to enable development of novel thermal control technologies. This loop heat pipe consists of a cylindrical evaporator, compensation chamber, condenser along with vapor and liquid lines, which can be easily assembled/disassembled for test purposes. This laboratory setup is especially designed to enable the visualization of fluid flow and phase change phenomena.