Search Results

Sundstrand is investigating 270-Vdc/hybrid 115-Vac electrical power generating and distribution systems technology so as to be well prepared to offer such systems for future aircraft applications. The approach taken has been to design, build, and test a representative system that meets or exceeds the tightest of the performance standards as defined by miliary standards. This paper describes a single-channel, 120-kW hybrid system and presents some typical performance data. The dc bus supplies a 30-kVA, 400-Hz, 115-Vac inverter; constant power load banks of up to 150 kW; and a resistive load bank of up to 90 kW. System simulation studies indicated the potential for unstable operation due to the negative impedance of the constant power load in conjunction with the source ripple filter and the load EMI filters. Unstable voltage and current were observed in system testing when the magnitude of the source impedance was not sufficiently below that of the load impedance.

Sundstrand has been investigating 270-Vdc/hybrid 115-Vac electrical power generating systems (EPGS) technology in preparation for meeting the electrical power generating system (EPGS) requirements for future aircraft (1). Systems such as the one being investigated are likely to be suitable for the More-Electric Aircraft (MEA) concepts presently under industry and military study. The present Sundstrand single-channel testbed is being further expanded to better understand the electrical system performance characteristics and power quality requirements of an MEA in which traditional mechanical subsystems are replaced by those of a “more-electric” nature. This paper presents the most recent Sundstrand 270-Vdc system transient performance data, and describes the modifications being made to the 270-Vdc/hybrid 115-Vac testbed.

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.

An optical sensor for the detection of carbon dioxide concentrations and stable isotope ratios is described. Either a continuous wave, fiber-coupled distributed feedback laser or an external cavity laser is used to pump an optical cavity absorption cell in cw-Cavity Ringdown Spectroscopy (cw-CRDS). This technique exploits the sensitivity enhancements provided by the long effective pathlength from the optical cavity created between two highly reflective mirrors (R>0.9999). The inherently high precision of the technique combined with its rapid data throughput allows for reliable measurements of both concentration and the isotopic composition of the sampled carbon dioxide. Data collected using a prototype of this sensor could be useful for monitoring module occupancy, crew health (through breath tests), and plant growth chambers.

As mission length and the number and complexity of payload experiments increase, so does the probability of thermodegradation contingencies (e.g. fire, chemical release and/or smoke from overheated components or burning materials), which could affect mission success. When a thermodegradation event occurs on board a spacecraft, potentially hazardous levels of toxic gases could be released into the internal atmosphere. Experiences on board the Space Shuttle have clearly demonstrated the possibility of small thermodegradation events occurring during even relatively short missions. This paper will describe the Combustion Products Analyzer (CPA), which is being developed under the direction of the Toxicology Laboratory at Johnson Space Center to provide necessary data on air quality in the Shuttle following a thermodegradation incident.

The paper compares the size, weight and performance characteristics of hydraulic, pneumatic and electro-mechanical actuators for general aviation flight controls. Mathematical models for each type are presented. Actuator designs for specific control tasks in realistic light airplane applications are compared with each other. It is shown that electro-mechanical actuators utilizing the recently developed samarium-cobalt technology have significant advantages in terms of size and weight requirements while yielding very fast response.

Ice adhesion characterization relies heavily on experimental data, especially when dealing with fracture parameters. In this paper, a complementary framework encompassing experimental testing with the numerical treatment of the fracture variables is proposed to provide a physical description of adhesive fracture propagation at the interface of an iced structure. The tests are based on a quasi-static flexural testing setup composed of a displacement-driven actuator and an iced plate. The measured crack length and plate deflection provide the data to be analyzed by the Virtual Crack Closure Technique in order to approximate the critical energy release rate required to study adhesive fracture propagation. The critical energy release rate in mode II is under-predicted and its value is approximated using its counterpart in mode I.

An automated nutrient replenishment system has been developed in order to provide a constant electrical conductivity (EC) value for the nutrient solution over the period of plant growth. A single nutrient film technique (NFT) system developed by the Tuskegee University NASA Center was equipped with the EC control system for growth trials with sweetpotatoes. The system is completely controlled and monitored by a PC through the use of LabView instrumentation and data acquisition software. A submersible EC probe driven by an EC controller measures the EC of the nutrient solution reservoir. EC values are passed from the controller to the PC through analog outputs. If the EC is outside a given range, the PC sends a signal to one of two solenoid valves that allow concentrated stock solution or deionized water to enter the reservoir to either raise or lower the EC respectively. For this application the set point is 1200μS cm-1, with a dead band from 1180 to 1220μS cm-1.

The Ames Research Center initiated a program in 1975 to provide the critical information required for the design of integrated avionics suitable for general aviation. The program has emphasized the use of data busing, distributed microprocessors, shared electronic displays and data entry devices, innovative low-cost sensors, and improved functional capability. Design considerations include cost, reliability, maintainability, and modularity. As a final step, a demonstration advanced avionics system is being designed, fabricated, and flight tested. The purpose of this paper is to provide a functional description of the Demonstration Advanced Avionics System including a description of the system architecture in order to document the direction that the program is taking.

A questionnaire study was conducted to determine the present state-of-the-art in the field of design tool (research and development) flight simulators. The major concern at this time appears to be the simulation of realistic external displays for visual reference by the pilot. Advance study is vitally necessary in the fields of VTOL/ STOL performance.stability and control, and instrumentation and/ or displays for terrain clearance and avoidance during high speed, low altitude flight. Also required are studies of g forces, zero g environment, and the use of drugs or hypnosis to control specific channels of communication in man during studies of his more significant sensors.

This paper describes the design of an intelligent control software architecture for advanced life support (ALS) applications that is dynamically reconfigurable. Such an architecture will dramatically decrease the downtime of ALS systems due to subcomponent failure and will improve safety and operational efficiency by supporting reconfiguration of the control system with a minimum of deactivation or shutdown of the systems being controlled. In addition to increasing system reliability and safety in deployed ALS systems, this architecture will also support ALS technology advancement by allowing the rapid integration of newly developed sensors, actuators and/or control algorithms for evaluation or comparison purposes in ALS ground test beds. Detailed discussion is given for the motivation as well as the design of both the architecture and experiments to validate the architecture’s improvement over current designs.

A fail-operative stability augmentation system for the C141 jet transport aircraft yaw control axis is described. Triple-redundant sensors and signalling are used in conjunction with a dual-output, monitored servo system. Majority-rule voting logic, comprised of digital logic gates, operates directly upon conventional 400 cps suppressedcarrier data-modulated signals for fault rejection. Self-contained means for semi-automatic preflight checkout as well as operational failure warning and disconnect provisions are described. It is shown that the effect of redundancy is to reduce by several orders of magnitude the probability of a hardover failure occurrence.

The BRIC-LED (Biological Research In Canisters-Light Emitting Diode) PDFU (Petri Dish Fixation Unit) apparatus was originally developed to support the on-orbit growth and subsequent fixation of any biological material amenable to petri dish culture in space. The PDFU component has been modified to support a two-stage fluid provision option so that investigations can incorporate an initial injection of a biologically active solution followed by a subsequent fixative injection to terminate the experiment in space. Crew-operated actuator tools initiate the delivery of the liquid treatments. Aseptic protocols have been developed which permit the entire experiment to be conducted under sterile conditions.

For forty years, the Aerospace Industry has seen a 1 percent per week growth in the capabilities of its computers, memory devices, display generators, sensors, and signal processors. At first, this was led by the Aerospace Industry, but now the leadership has been taken over by commercial companies providing for consumer products, and aerospace companies have been falling behind because of low sales, no new product developments, drawn out development programs, and their related problems. Avionics companies can see that every year, one box can replace two, and so they have one of two strategies: Be the supplier of that one box, or claw out a niche that will require their box to continue to be required. As hardware costs drop, more and more of what they do is software and many of them have previously down-played software by buying it or by using warmed-up old software.

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.

This SAE Aerospace Information Report (AIR) is devoted to the challenges of applying optics to new advanced RF analog systems only; digital data link applications are covered elsewhere in protocol/architecture specific documents like Fibre Channel, ATM, Ethernet, Sonet, etc.

This document establishes training guidelines applicable to fiber optic safety training, technical training and fiber awareness for individuals involved in the manufacturing, installation, support, integration and testing of fiber optic systems. Applicable personnel include: Managers Engineers Technicians Logisticians Trainers/Instructors Third Party Maintenance Agencies Quality Assurance Shipping Receiving Production Purchasing

This document establishes training guidelines applicable to fiber optics engineer technical training for individuals involved in the manufacturing, installation, support, integration and testing of fiber optic systems. Applicable personnel include:

This document establishes training guidelines applicable to fiber optic fabricator technical training for individuals involved in the manufacturing, installation, support, integration and testing of fiber optic systems. Applicable personnel include:

This document establishes training guidelines applicable to fiber optic installer technical training for individuals involved in the manufacturing, installation, support, integration and testing of fiber optic systems. Applicable personnel include: Managers Engineers Technicians Trainers/Instructors Third Party Maintenance Agencies Quality Assurance Production