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A comparison was done of the prediction capabilities for lightning indirect effects of two two-dimensional (2-D) computer codes using two graphite structural test fixtures. The two codes evaluated were an internal Boeing Method-of-Moments code and a commercially available Boundary Element method code. The codes were compared against each other and against test data. The purpose was to evaluate the prediction capabilities of both codes for use in predicting lightning indirect effects on internal components of graphite structure. Since 2-D codes are much easier to use than 3-D codes, they could be widely used in trade studies and design evaluations for lightning indirect effects protection of composite aircraft. The first code, REDIST, is a Method-of-Moments code developed in the 1980’s for use on the B-2. The REDIST code has short run times and is somewhat easier to use than the second code that was investigated.

Airplane level lightning testing is used to verify lightning protection effectiveness of airplane systems. Time domain pulse and frequency domain swept-frequency transfer function tests are two acceptable airplane level ground test methods available to the aircraft manufacturer. Although both methods offer an acceptable verification means, both methods pose their own technical challenges. The intent of this paper is to present data collected from lightning pulse and swept-frequency transfer function tests conducted on a 777 airplane, and to compare these tests results. The data collected for this comparison includes several pulse and transfer function measurements made on flight control wiring routed along the rear spar of the 777 graphite vertical and horizontal stabilizers. The pulse measurement involved injecting 20 kA damped sinusoid pulse into the tip of the stabilizer while measuring the induced voltage on an individual wire within select shielded flight control bundles.

Both humans and onboard radiosensitive systems (electronics, materials, payloads and experiments) are exposed to the deleterious effects of the harsh space radiations found in the space environment. The purpose of this paper is to present the space radiation environment extended to deep space based on environment models for the moon, Mars, Jupiter, and Saturn and compare these radiation environments with the earth's radiation environment, which is used as a comparative baseline. The space radiation environment consists of high-energy protons and electrons that are magnetically “trapped” in planetary bodies that have an intrinsic magnetic field; this is the case for earth, Jupiter, and Saturn (the moon and Mars do not have a magnetic field). For the earth this region is called the “Van Allen belts,” and models of both the trapped protons (AP-8 model) and electrons (AE-8 model) have been developed.

Nickel-5 Aluminum (95 % Nickel-5 % Aluminum) is widely used in the aircraft engine industry. The excellent adhesive and cohesive strength of the coating, oxidation resistance and machinability make it an ideal material as both a bond coat for subsequent topcoats and as a build up material for dimensional restoration of worn or mismachined components. Plasma spraying has traditionally been the thermal spray process used to apply nickel aluminum, and the technical properties and performance characteristics are well documented. More recently, wire arc sprayed nickel aluminum is becoming widely used as an alternative to plasma spraying due to higher bond strengths, reproducibility, better machinability and more favorable economics. This paper presents the results of a testing program designed to compare the technical properties of arc sprayed versus plasma sprayed Nickel-5 Aluminum coatings.

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.

Technological advances have made it possible to advance assembly of aircraft from the days of “Rosie the Riveter” to automated manufacturing facilities of the future. Improvements in CNC controlled machines, called Positioners, and tooling, called End Effectors, have enabled the assembly process to pass from, two people, to robots working on opposite sides of a panel. Further developments with Multi-functioning End Effectors and stiffer more accurate Positioners have reduced the station to station cycle times of completely assembled panels. New generation systems show even greater promise for, not only lower cycle times, but lower investment costs and higher reliability.

This paper deals with the Complex Simulation Model of Human Organism (HOCSM) intended for various problems' solutions of the Manned Space Objects Ecological and Technical System (ETS) development. Among the fundamental problems of the ETS development requiring the HOCSM adaptation are: (a) forming the mass and energetic loads of spacecraft crew for the simulation of the ETS functions; (b) the investigation of environment effects on a human organism and its responses; (c) the analysis of interactions between the crew and the individual life support system or its functional blocks; (d) the decisions of design problems for development of the anti exposure and space suits. The HOCSM, under consideration, is based on the general theory of functional systems and includes formalistic descriptions of following human organism functional systems: a cardiovascular systems, an external respiration system, a thermoregulation system and a water-salt balance system.

The paper defines a “best” estimate of system effectiveness or reliability as one that minimizes the potential loss due to either overestimating or underestimating such a system figure of merit. A loss function is expressed in terms of the decision maker's order of preference for the consequences of either overestimation (underkill) or underestimation (overkill). However, in order for an estimate to be optimal, sufficient information at the system level should be provided. This lack or abundance of information is reflected in the variability of the measurement of system effectiveness or reliability. The variability and central tendency of this measurement are obtained from the variability and central tendency of the component data. This is achieved through the combined use of effectiveness or reliability models, Monte Carlo simulation and/or probability moments, and Bayesian statistics.

As space flights tend to be more prolonged problems of oxygen generation by physicochemical means assume greater importance. The paper deals with the water, electrolysis process, CO2 concentration and processing organisation schemes. Some operational results of the system for electrolysis of aqueous alkali solution and CO2 removal on Mir space station are presented. Expected characteristics of the complex system for oxygen generation from carbon dioxide are considered.

During the certification of an airplane, the chances of encountering icing conditions as defined in the Federal Aviation Regulations (FAR) are so small that the satisfactory performance of an anti-icing system has to be established by methods other than flight tests in FAR icing conditions. The regulations, however, do not specify a set of standard procedures for evaluating the anti-icing capability of a system. The methods used within the industry, therefore, vary very widely in type, scope, and accuracy. This paper describes an approach used by Gates Learjet that is simple and inexpensive to be within the reach of any manufacturer, and accurate enough to contribute towards the creation of a standard procedure within the whole industry.

This work presents a comprehensive numerical model for ice accretion and Ice Protection System (IPS) simulation over a 2D component, such as an airfoil. The model is based on the Myers model for ice accretion and extended to include the possibility of a heated substratum. Six different icing conditions that can occur during in-flight ice accretion with an Electro-Thermal Ice Protection System (ETIPS) activated are identified. Each condition presents one or more layers with a different water phase. Depending on the heat fluxes, there could be only liquid water, ice, or a combination of both on the substratum. The possible layers are the ice layer on the substratum, the running liquid film over ice or substratum, and the static liquid film between ice and substratum caused by ice melting. The last layer, which is always present, is the substratum. The physical model that describes the evolution of these layers is based on the Stefan problem. For each layer, one heat equation is solved.

This paper presents an approach to numerically simulate greenhouse windnoise. The term “greenhouse windnoise” here describes the sound transferred to the interior through the glass panels of a series vehicle. Different panels, e.g. the windshield or sideglass, are contributing to the overall noise level. Attached parts as mirrors or wipers are affecting the flow around the vehicle and thus the pressure fluctuations which are acting as loads onto the panels. Especially the wiper influence and the effect of different wiper positions onto the windshield contribution is examined and set in context with the overall noise levels and other contributors. In addition, the effect of different flow yaw angles on the windnoise level in general and the wiper contributions in particular are demonstrated. As computational aeroacoustics requires accurate, highly resolved simulation of transient and compressible flow, a Lattice-Boltzmann approach is used.

For most car manufacturers, wind noise from the greenhouse region has become the dominant high frequency noise contributor at highway speeds. Addressing this wind noise issue using experimental procedures involves high cost prototypes, expensive wind tunnel sessions, and potentially late design changes. To reduce the associated costs as well as development times, there is strong motivation for the use of a reliable numerical prediction capability early in the vehicle design process. Previously, a computational approach that couples an unsteady computational fluid dynamics solver (based on a Lattice Boltzmann method) to a Statistical Energy Analysis (SEA) solver had been validated for predicting the noise contribution from the side mirrors. This paper presents the use of this computational approach to predict the vehicle interior noise from the windshield wipers, so that different wiper placement options can be evaluated early in the design process before the surface is frozen.

A Non-Planar Vortex Lattice Method (VLM) has been combined with a Two-Dimensional Surface Panel Method for computing the aerodynamic characteristics of finite wings in incompressible inviscid flow. This numerical model can be applied to wings with thickness and arbitrary planform, and requires very little computing time when compared to Three-Dimensional Surface Panel Methods currently in use. The formulation of the present method is described in detail, and results from its application to three wing configurations are presented. The results obtained using the present method are compared with results obtained using the VSAERO code and with experimental data. Good correlation is demonstrated in all cases.

A computational process for early stage vehicle shape assessment for automotive front window buffeting and greenhouse wind noise is presented. It is a challenging problem in an experimental process as the vehicle geometry is not always finalized. For example, the buffeting behavior typically worsens during the vehicle development process as the vehicle gets tighter, leading to expensive late counter measures. We present a solution using previously validated CFD/CAA software based on the Lattice Boltzmann Method (LBM). A CAD model with realistic automotive geometry was chosen to simultaneously study the potential of different side mirror geometries to influence the front window buffeting and greenhouse wind noise phenomena. A glass mounted mirror and a door mounted mirror were used for this comparative study. Interior noise is investigated for the two phenomena studied. The unsteady flow is visualized and changes in the buffeting and wind noise behavior are explored.

Computerized Aided Engineering (CAE) techniques currently used in the design of impellers is presented. Both computerized flow performance analysis and structural integrity analysis methods are discussed. Computer graphic capabilities used in the design cycle are also listed. An approach to evaluate the structural integrity of impellers under steady state and dynamic loading is given. Correlation between analytical and test results is presented. The emphasis of the paper is placed on the structural integrity aspects.

This paper presents an overview of the Computer Aided Systems Engineering and Analysis (CASE/A)-ECLSS series which is designed as a generalised ECLSS design and analysis package. This system was developed under NASA MSEC contract NAS8-36407 to meet the Systems Analysis requirements of the Space Station ECLSS. The Space Station represents an order of magnitude increase in complexity over current Spacecraft technologies and will seriously tax current analysis techniques. This program is capable of simulating atmospheric revitalization systems, water recovery and management systems, and single phase active thermal control systems. The program evolved from both the G189A and the SINDA programs and shares the G189A architectural concepts. The designer/ analysis interface is graphics based and allows the designer to build a model by constructing a schematic of the system under consideration.

In designing large booster structures, a major area requiring extensive stress analysis is the discontinuous region, such as the skirt intersection, the sculptured joint, and the reinforced opening. This paper presents a computer solution of stresses and displacement in a typical skirt intersection consisting of (1) a variable-walled transition cylinder, (2) a skirt cylinder, (3) a spheroidal dome, and (4) an infinitely long cylinder. The solution of the variable-walled cylinder is accomplished by integrating numerically a fourth-order differential equation. From the computer analysis the theoretical stresses at the intersection of a typical large-diameter rocket motor case are obtained.

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.