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Technical Paper

A Description and Assessment of Intermodule Ventilation as Planned for International Space Station Alpha

The International Space Station Alpha (ISSA) conceptual design has several notable differences from previous Space Station design efforts. One key difference centers around the Intermodule Ventilation (IMV). While previous IMV designs incorporated standalone ducts at each element-to-element interface, the present approach includes several IMV ducts which are configured into the central Temperature and Humidity Control (THC) ducting networks. A simplified analytic technique is presented, which assesses compliance of the overall IMV approach to the established requirement which limits IMV short circuiting to a maximum of 40% at a fan flow rate of 140 cfm. Test results (from the Space Station Freedom IMV Test) and theoretical performance results are input to the analytic technique.
Technical Paper

Standards for Airborne Power Distribution Systems Used to Power Portable Medical Equipment

This paper accentuates the need for standards for airborne medical power supply system (AMPSS) installations. Potential electrical shock hazards through improperly designed AMPSS are discussed. The airplane electrical power system and the airplane environment are described and compared to that of a hospital. Regulatory bodies and medical device industry standards are discussed. Design safety requirements contained in the National Electric Code and ASTM standard for ground ambulances are identified. Federal regulations and standards for fixed wing medical transport units are compared to the above mentioned standards to demonstrate the lack of guidance material for medical airborne applications. This paper recommends that associations such as ASTM or SAE begin development of a standard for airborne applications based on existing standards.
Technical Paper

The Application of Grab and Time Integrated Sampling to the Characterization of Trace Contaminants Contributed by the Docking and Integration of the Priroda Module to Space Station Mir

The docking and integration of the Priroda module into the Space Station Mir Complex in 1996 provided a unique opportunity to assess the potential impact on the trace contaminant concentrations in the station complex. Since Priroda was substantially loaded with new US flight hardware, the data are potentially relevant to future similar operations associated with the buildup of the International Space Station. Grab samples were collected to assess the Priroda concentrations prior to integration and to capture the profile of concentrations after the start of Priroda inter-module ventilation. A long term time integrated sampler was configured for collection of canister samples over a time interval of seven days.
Technical Paper

Fabrication Techniques — HY-140 for Flight Type Pressure Vessels

This paper discusses fabrication results experienced with HY-140 steel flight type pressure vessels. HY-140 steel is a recently developed quenched and tempered alloy (5Ni-CR-Mo-V) structural steel with a yield strength of 140,000 psi. Fabrication techniques applied, the tooling used, and the problems encountered are described in detail.
Technical Paper

Identify/Utilize Process Capability Information to Predict Variation in Aircraft Early Design

Process capability information, combined with simplified component geometric models and assembly variation transfer functions built from Monte Carlo simulations, can give aircraft designers early estimations of product variability. Such predictions traditionally must wait for detailed component designs-after many important sourcing and production decisions have been made and when alternative designs are no longer an option. An additional benefit of early variation analysis is identification of major contributors to critical assembly variation. This information can alert downstream part designers of potential problem areas and also identify key manufacturing processes capabilities that must be verified, measured, and/or improved. This paper presents an efficient, top-down approach to move assembly variation analysis into early stages of aircraft development.
Technical Paper

Minimum Operation Performance Standard for Aircraft Batteries

At the request of the FAA, a committee was formed by the RTCA organization to prepare a Minimum Operating Performance Standard (MOPS) for Rechargeable Aircraft Lithium Battery Systems. This committee has being working for the last 2 years and completed the final draft during their 6th meeting in February 2008. Lithium Battery approval will be different than Nickel-Cadmium and Lead-Acid in that they will incorporate additional safety and documentation requirements. The MOPS, to be used by the FAA as the basis for a Technical Standard Order (TSO), includes the testing and evaluation criteria required for rechargeable lithium battery systems airworthiness demonstration.
Technical Paper

Minimum Operation Performance Standard for Aircraft Batteries

Radio Technology Commission for Aeronautics (RTCA) at the request of the Federal Aviation Administration (FAA) formed a committee to prepare a Minimum Operating Performance Standard (MOPS) for aircraft batteries. The MOPS was limited to rechargeable and starting batteries as power sources for equipment installed in aircraft. This committee has being working for the last 3 years and completed the final draft during their 6th meeting in April 2004. The MOPS, to be used by the FAA as the base for a Technical Standard Order (TSO) in preparation, includes the testing and evaluation criteria required for secondary Lead-Acid (Pb-A) and Nickel-Cadmium (Ni-Cd) batteries airworthiness demonstration.
Technical Paper

Commercial Aircraft Batteries

Advancements in commercial aircraft batteries have been driven by changes in licensing requirements. Early model aircraft needed batteries to comply with a five minute emergency power requirement. This short time requirement was later incremented to 30 minutes and was recently increased to one hour. These requirements have changed to meet the demands of emergency equipment which, over time, have grown in sophistication and number. Traditional flight-by-cable aircraft require emergency power mostly for instrumentation to help reach a zone were continued visual flight and landing is possible. With the advent of flight-by-wire aircraft, emergency power is not only necessary for instrumentation, but is critical to flight itself. There is no single method for choosing a battery. The requirements for a battery will depend on many factors, including the availability of alternate sources of emergency power.
Technical Paper

Achieving “One Up Assembly” by Reduction of Interface Burr Height in Aluminum, Graphite, and Advanced Titanium/Graphite Hybrid (TiGr) Material

In aircraft assembly, a burr left at the interface of any joint is considered a source of potential fatigue life degradation. Burrs can act as an additional stress concentration, leading to fretting, inducing failures. It could also open moisture paths resulting in corrosion. Burrs can affect the fatigue life of various structures differently depending on the type of joint, material, fastener, and installation process. Traditionally, we have disassemled and deburred the interface with various tools such as sand paper, file, chamfer tool, hook, or other tools. Disassembly and deburring of airplane major parts are time consuming and costly. In addition achieving “one up assembly” is not viable unless interfacial burr can be eliminated or reduced to the point where it will not affect fatigue life. In this investigation, the possibility of “one up assembly” via creation of concentric and adjacent clamping in various materials is studied.
Technical Paper

Summary of Resources for the International Space Station Environmental Control and Life Support System

The assembly complete Environmental Control and Life Support (ECLS) system for the International Space Station (ISS) will consist of components and subsystems in both the U.S. and International partner elements which together will perform the functions of Temperature and Humidity Control (THC), Atmosphere Control and Supply (ACS), Atmosphere Revitalization (AR), Water Recovery and Management (WRM), Waste Management (WM), Fire Detection and Suppression (FDS), and Vacuum System (VS) for the station. Due to limited resources available on ISS, detailed attention is given to minimizing and tracking all resources associated with all systems, beginning with estimates during the hardware development phase through measured actuals when flight hardware is built and delivered. A comprehensive summary of resources consumed by the U.S.