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In analyzing charged particle spectra in space due to galactic cosmic rays (GCR) and solar particle events (SPE), the conversion of particle energy spectra into linear energy transfer (LET) distributions is a convenient guide in assessing biologically significant components of these spectra. The mapping of LET to energy is triple valued and can be defined only on open energy subintervals where the derivative of LET with respect to energy is not zero. Presented here is a well-defined numerical procedure which allows for the generation of LET spectra on the open energy subintervals that are integrable in spite of their singular nature. The efficiency and accuracy of the numerical procedures is demonstrated by providing examples of computed differential and integral LET spectra and their equilibrium components for historically large SPEs and 1977 solar minimum GCR environments. Due to the biological significance of tissue, all simulations are done with tissue as the target material.

The collision of two or more liquid jets may provide considerable atomisation and efficient mixing of injected substances at the same time. This phenomenon is used, among others, in rocket engines, where the fuel and oxidiser are introduced separately and almost immediately mixed through self-impingement. Depending on the injection and operating conditions, diverse configurations of impinging jets are used, such as doublets, triplets, etc. The appropriately designed injectors and operating conditions ensure the short length of the liquid structures that are developed as a result of the jets’ collision, as well as lead to intensive atomisation. The following work presents a numerical analysis of some impinging jets with relatively high Reynolds numbers. Two different nozzle diameters were considered, which were designed for fuels with different calorific values and stoichiometric ratios.

This paper presents an innovative solution of portable drilling machine, lightweight and low cost, dedicated to drilling operations on single and double curved aircraft structure. Aircraft Standard drilling process mainly uses drilling templates combined with Automated Drilling Units (ADU) which is a very efficient solution. However, the management of templates and ADUs is a time consuming and costly task in regards to the large quantity of existing references spread over every aircraft production sites. Therefore, to help reducing those costs and also workload, the concept of the Numerical Template (NCT) has been designed, using classic and robust mechanical devices, hand-held, lightweight and universal. NCT architecture concept could led to a family of NCT with different dimensions of frame parts(X,Y,Z), fitted to the targeted area geometry. The system is able to guaranty an accuracy of ± 0.5 mm and a normality of ±0.5°.

Recently a new emphasis has been placed on engineering applications of space radiation analyses and thus a systematic effort of Verification, Validation and Uncertainty Quantification (VV&UQ) of the tools commonly used for radiation analysis for vehicle design and mission planning has begun. There are two sources of uncertainty in geometric discretization addressed in this paper that need to be quantified in order to understand the total uncertainty in estimating space radiation exposures. One source of uncertainty is in ray tracing, as the number of rays increase the associated uncertainty decreases, but the computational expense increases. Thus, a cost benefit analysis optimizing computational time versus uncertainty is needed and is addressed in this paper. The second source of uncertainty results from the interpolation over the dose vs. depth curves that is needed to determine the radiation exposure.

This paper describes the thermal modeling and analyses performed on the LISA Technology Package (LTP), with special attention to the frequency domain requirements on the sensitive instrumentation. The new approach is presented, and the modeling and analysis phases are described in detail. Results about LTP thermal stability in the frequency domain are shown, and obtained though two alternate approaches. The first one consists in the study of the transient response of the system to a periodic input with a frequency equal to the minimum frequency of interest, using the well known low-pass filtering properties of the thermal systems. The second is based on the generation of a time dependent input, starting from its Power Spectral Density definition: this input is used to run a transient thermal analysis and finally transform its results into the frequency domain. Thermal stability assessment studies have been performed also at spacecraft level and are well described in [ref. 3].

Structures in cold weather environments are susceptible to atmospheric ice formation. A fracture mechanics based approach is proposed for in situ characterization of the interfacial fracture energy of ice on different substrates. This paper summarizes the development of the experimental and analytical framework to measure the ice adhesion energy, calibrated on static ice. The testing configuration utilizes a shaft-loaded blister test to produce stable crack propagation, from a well-defined pre-crack at the interface of the ice layer and the substrate. Measurements of the fracture energy are taken over a range of ice thicknesses and surface roughnesses. The developed analytical framework to estimate adhesion energy are verified and calibrated via finite element numerical simulation of the proposed geometric configuration and employing cohesive surfaces along the interface to simulate the crack nucleation and propagation process.

The riveting process in the aerospace industry underlies high requirements to achieve the expected manufacture quality. Process parameters, the choice of materials, and the joint configuration are some influencing factors that can affect the mechanical properties of riveted joints. These high requirements constitute challenges that drive manufacturers to a better understanding of the riveting process. The numerical study of the effect of the installation parameters on the mechanical properties of mechanically fastened joints is one tool to achieve this aim. Usually, three-dimensional finite element simulations of both installation process and mechanical loading of the joint in service must be performed to make detailed numerical predictions of the joint behavior. This paper aims at the reduction of the computational effort.

This article presents a structural analysis of the Unmanned Aerial System UAS-S4 ETHECATL. Mass, center of gravity position and mass moment of inertia are numerically determined and experimentally attested using the pendulum method. To determine the mass moment of inertia, a bifilar torsion-type pendulum is used for the Z-axis and a simple pendulum for the X and Y axes [14]. A nonlinear dynamic model is developed for the rotational motion about the center of gravity (Gs) of the tested system, including the effects of large-angle oscillations, aerodynamic drag, viscous damping and additional mass effects. MATLAB genetic algorithms are then used to obtain the values of mass moment of inertia that would validate the experimental data with the numerical results. The experiment used data gathered by three sensors: an accelerometer, a gyroscope and a magnetometer. Therefore, a method is used to calibrate these three sensors.

This paper presents a coupled numerical and experimental study of an unconventional wing profile such as cp-180-050-gn (Cambered plate C = 18% T = 5% R = 0.78). This wing profile deals with low speeds. It is not currently used on any aircraft model. Otherwise, it presents interesting performances that can be exploited for the design of low-speed STOL or VTOL aircraft by mean of the very high lift that it can generate and can fit with different uses such as VAWT, cyclorotors drones, which are designed explicitly for low-speed operations. After a preliminary CFD assessment of the wing a complete experimental characterisation also at high angles of attack has been performed. The excellent agreement between CFD and experiments has allowed producing a complete analysis of the behaviour of the wing profile both before and after stall conditions. This study has the objective of analysing the viability of such an unconventional wing in traditional or over-stalling conditions.

Hybrid laminar flow control (HLFC) is one of the most practically promising aircraft drag reduction technologies. We have investigated both numerically and experimentally aerodynamic characteristics of HLFC airfoil and wing at high subsonic, high Reynolds number conditions. In this paper we report the result of a wind tunnel test on drag characteristics of two-dimensional HLFC airfoils with porous and slot suction approach under some adverse factors against laminar flow, and a numerical analysis of the wind tunnel data, which is based on the boundary layer calculation with new transition prediction method allowed for the adverse factors and the Squire-Young drag formula.

The present work aims to use complex tools for the calculation of vehicle dynamics, using optimization analysis. The study was applied to a single seat off-road prototype that has independent suspension, Double A or WishBones type, both on the front and rear axles and whose main objective will be the analysis of the prototype suspension arms fixing points. A multi-body model was created by MotionView software and straight-line acceleration and deceleration analyzes were applied to obtain better longitudinal load transfer ratios for the axes, besides the force measurements for the arm connections during these events. After the creation of the multi-body model, some studies using optimization tools, through HyperStudy software, were performed in order to obtain the new positions of the attachment points in the chassis, achieving a better dynamic suspension design.

The nature of aerospace innovation has changed dramatically in the past few decades, including some subtle changes that might go unnoticed to a casual observer outside our industry. The achievements of the 1950s through the 1990s were often epitomized by events that made headlines throughout the world - for example, breaking the sound barrier, walking on the Moon, receiving the first images from a roving vehicle on Mars, or launching the first airliner designed solely using computers. Aerospace engineers today are creating feats that are no less innovative or impressive but that often lack the universal sensational appeal of those past “miracles.” Now the accomplishments are likely to be concerned with using data more effectively to reduce risk and enhance the safety and affordability of products and services rather than flying faster, higher or more stealthily.

A simulation campaign, EXEMSI, organized by the ESA Long Term Programme Office was held from Sept. 7th to Nov. 6th 1992 in Germany. The crew- three men and one woman- was placed in confined and isolated living conditions in an hyperbaric chamber, thus simulating a space environment. During this two-month period, a nutritional investigation was conducted with a twofold objective: from an operational standpoint, to define and setup the food system; from a scientific standpoint, to collect data on the spontaneous nutritional behavior of the crew. In this scope, a well-defined food system was implemented. For food management and on line nutritional data collection, dedicated software has been developed. This software based on using barcodes permitted an accurate recording of food consumption for each crewmember. Nutritional assessments were then performed daily for each crewmember -or EMSInaut- by summing the nutritional values of all the foods consumed.

This paper shows how an “Airport City”, Chicago-O'Hare International Airport, has acted as a magnet and catalyst for industrial, commercial and residential growth in the Chicago area. Land surrounding the airport has appreciated 250 times the 1942 rate. O'Hare is the sixth leading employer in the Chicago area, though Chicago is the second most populated consolidated area in the U.S. Only three of fourteen communities near O'Hare had greater disposable incomes than those generated by air transportation at O'Hare in 1970.

Measurements were made of helium permeation rates for O-rings subjected to helium pressure on one side and vacuum on the other. Helium pressures up to 1000 psi were used in the investigation. Gland designs included grooves for O-ring squeezes from 25 to 75 percent, dual O-ring grooves, and two tongue-and-groove configurations. Calculations were made of the expected permeation rates based on material permeability data. The results of this study indicate that dual O-rings and close-fitting tongue-and-groove designs provide permeation rates that are lower than the rates that are calculated by conventional methods.

The on-board production of oxygen is demanded for future long-term missions such as International Space Station, Lunar base and missions to Mars. The needed oxygen can be recovered by electrolysing the water produced by the carbon dioxide processing system or other on-board water sources like water condensate. This way the oxygen loop will be closed. Since 1985 in a harmonised programme sponsored by the European Space Agency (ESA) and the German Space Agency (DARA), the required technology for an air revitalisation system (ARS) is being developed. The system is based on carbon dioxide concentration using solid amine water steam desorption, carbon dioxide hydrogenation (Sabatier) and fixed alkaline electrolysis. This paper reports on the manufacturing and testing of the fixed alkaline electrolyser (FAE) system designed for a 3-person capability and it discusses the current status of the ARS.

Advanced technology air separation modules for use in on-board Inert gas generation systems (OBIGGS) were investigated in a recently completed Air Force development program. These modules use hollow fiber permeable membranes that are compatible with a fighter aircraft environment and have no moving parts. Extensive ground testing revealed that the advanced modules offer an order of magnitude savings of weight and volume compared to other air separation modules. Hence, the advanced modules were used in an in-dapth study of OBIGGS for fighter aircraft applications. A best choice OBIGGS for a generic ATF configuration and a comparison of the best choice OBIGGS with other aircraft fuel tank fire protection systems are discussed.

Fuel on-board dehydration during flight technologies has been modeled and experimentally studied on a laboratory testing setup in normal specific gas flow rates range of 0.0002-0.0010 sec-₁. Natural air evolution, ullage blowing and fuel sparging with dry inert gas have been studied. It has been shown that natural air evolution during aircraft climb provides a significant, substantial, but insufficient dehydration of fuel up to 20% relative. Ullage blowing during cruise leads to a constant, but a slow dehydration of fuel with sufficient column height concentration gradient. Dry inert gas sparging held after the end of the natural air evolution or simultaneously with natural air evolution provides rapid fuel dehydration to the maximum possible values. It potentially may eliminate water release and deposition in fuel to -50°C. It has been found that for proper dehydration, necessary and sufficient volume of dry inert gas to volume of fuel ratio is about 1.