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The paper describes a numerical study, supported by experiments, on light aircraft 2-Stroke Direct Injected Diesel engines, typically rated up to 110 kW (corresponding to about 150 imperial HP). The engines must be as light as possible and they are to be directly coupled to the propeller, without reduction drive. The ensuing main design constraints are: i) in-cylinder peak pressure as low as possible (typically, no more than 120 bar); ii) maximum rotational speed limited to 2600 rpm. As far as exhaust emissions are concerned, piston aircraft engines remain unregulated but lack of visible smoke is a customer requirement, so that a value of 1 is assumed as maximum Smoke number. For the reasons clarified in the paper, only three cylinder in line engines are investigated. Reference is made to two types of scavenging and combustion systems, designed by the authors with the assistance of state-of-the-art CFD tools and described in detail in a parallel paper.

Offering aircraft fuel efficiency improvements of 30 to 40% over the powerplants it will replace, PW2037 retrofit in the 727-200 Advanced and B-52 aircraft is attracting heightened interest. A comparison of PW2037 technical characteristics with current aircraft powerplants substantiates the improvement potential.The engine installation and modifications necessary for aircraft system compatibility do not impose significant increases in complexity or cost. The resultant improvements in aircraft capability (727 and B-52) and economic viability to airlines (7271 produce aircraft uniquely suited to today's operational requirements and constrained equipment budgets.

The 912 engine is a well known 4-cylinder horizontally opposed 4-stroke liquid-/air-cooled aircraft engine. The 912 family has a strong track record: 40 000 engines sold / 25 000 still in operation / 5 million flight hours annually. 88% of all light aircraft OEMs use Rotax engines. The 912iS is an evolution of the Rotax 912ULS carbureted engine. The “i” stands for electronic fuel injection which has been developed according to flight standards, providing a better fuel efficiency over the current 912ULS of more than 20% and in a range of 38% to 70% compared to other competitive engines in the light sport, ultra-light aircraft and the general aviation industry. BRP engineers have incorporated several technology enhancements. The fully redundant digital Engine Control Unit (ECU) offers a computer based electronic diagnostic system which makes it easier to diagnose and service the engine.

In the course of CRYOSYSTEM phase B (development phase) financed by the European Space Agency, AIR LIQUIDE (France) and Astrium Space Infrastructure (Germany) have developed an optimized design of a −183°C freezer to be used on board the International Space Station for the freezing and storage of biological samples. The CRYOSYSTEM facility consists of the following main elements: - the CRYORACK, an outfitted standard payload rack (ISPR) accommodating up to three identical Vial Freezers - the Vial Freezer, a dewar vessel capable of fast and ultra-rapid freezing, and storing up to approximately 900 vials below −183°C; the dewar is cooled by a Stirling machine producing > 6 W at 90 K. The Vial Freezer is operational while accommodated in the CRYORACK or attached to the Life Science Glovebox (LSG). One CRYORACK will remain permanently on-orbit for several years while four Vial Freezers and two additional CRYORACKs support the cyclic upload/download of samples.

A hydrogen economy is an increasingly popular solution to lower global carbon dioxide emissions. Previous research has been focused on the economic conditions necessary for hydrogen to be cost competitive, which tends to neglect the effectiveness of greenhouse gas mitigation for the very solutions proposed. The holistic carbon footprint assessment of hydrogen production, distribution, and utilization methods, otherwise known as “well-to-wheels” carbon intensity, is critical to ensure the new hydrogen strategies proposed are effective in reducing global carbon emissions. When looking at these total carbon intensities, however, there is no single clear consensus regarding the pathway forward. When comparing the two fundamental technologies of steam methane reforming and electrolysis, there are different scenarios where either technology has a “greener” outcome.

This paper attempts to assess the benefits of a unique distributed propulsion concept, known as the Multi-Gas Generator Fan (MGGF) system, over conventional turbofan engines on civilian vertical takeoff and landing (VTOL) applications. The MGGF-based system has shown the potential to address the fundamental technical challenge in designing a VTOL aircraft: the significant mismatch between the power requirements at lift-off/hover and cruise. Vehicle-level performance and sizing studies were implemented using the Grumman Design 698 tilt-nacelle V/STOL aircraft as a notional personal air vehicle (PAV), subjected to hypothetical single engine failure (SEF) emergency landing requirements and PAV mission requirements.

In recent years, a tremendous interest has spawned towards adapting Lithium-Ion battery technology for aircraft applications. Lithium-Ion technology is already being used in some military aircraft (e.g., the F-22, F-35 and the B-2) and it has also been selected as original equipment for large commercial aircraft (e.g., the Airbus A380 and Boeing B787). The advantages of Lithium-Ion technology over Lead-Acid and Nickel-Cadmium technologies are higher specific energy (Wh/kg) and energy density (Wh/L), and longer cycle life. Saving weight is especially important in aircraft applications, because it can boost fuel economy and increase mission capability. Disadvantages of Lithium-Ion technology include higher initial cost, limited calendar/float life, inferior low temperature performance, and more severe safety hazards. This paper will present a direct comparison of a 24-Volt, 28Ah Lead-Acid and a 24-volt, 28Ah Lithium-Ion aircraft battery.

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.

Field studies of agricultural airplane operations indicated that airplane design parameters significantly affected aircraft productivity. Limitation of material discharge rate, while still securing uniform distribution pattern of ejected material, appeared to be a serious factor in restricting markets and holding down productivity. A computer program was written to explore possible gains from optimizing design parameters in a given market, to determine improvements which would result from extending the range of design parameters, and to study the effects of different operating procedures. The program actually “flies” an airplane through all steps of a mission. A mission is defined as a complete working day from preparation for first take-off to shutting down after last landing. All flight operations are defined in terms of airplane specifications and design parameters.

This paper presents the results of an investigation to improve design/analysis techniques for aircraft hydraulic systems. A design/analysis tool was developed by integrating control-surface commands and loads obtained from Aircraft Dynamic Simulator Software (ADSS) with an enhanced version of the HYdraulic TRansient ANalysis (HYTRAN) program. Control-surface commands and loads from an ADSS simulation of a selected maneuver were used as dynamic input to the HYTRAN program so that the hydraulic system response could be predicted throughout the maneuver. Predicted hydraulic system pressures and control-surface positions from the HYTRAN simulation of the maneuver were compared to flight-test data and were found to be in excellent agreement. The successful coalescence of the two independent software programs gives engineers a concurrent design/analysis tool that can be used to optimize hydraulic system designs during the very early stages of design.

An optimization technique has been developed on the Flight Design System (FDS) which examines available target and instrument constraints to determine an optimal target launch time for maximum instrument viewing in a cooperative launch scenario. By definition, a cooperative launch is a coordinated mission between an orbiting viewing instrument and a target which is launched from the ground at a time specified by instrument viewing requirements. The technique is designed to evaluate instrument constraints such as range and slewing rate limitations and analyze them parametrically with the relative target launch time to determine the effect on the instrument viewing period. Using the FDS, this technique can be utilized in a real-time situation by updating the instrument's position and re-evaluating applicable parameters to obtain an updated target launch time.

It is logistically unfeasible to supply the crew of a long-term space mission with earth-borne food-products only. Thus, in order to provide sufficient food for space missions exceeding one year, it is necessary to implement a plant breeding system on board, which can at least partly cover the crew’s nutritional needs. In the frame of a European Space Agency (ESA) feasibility study on Closed Loop Food Systems (CLFS) for Low Earth Orbit (LEO), Transit to Mars and Mars Surface scenarios, a nutrition selection algorithm was developed to define well equilibrated and diverse menus able to meet dietary requirements. First, an extensive, diversified crop list was compiled from a broad range of literature sources. Secondly, a database was constructed, containing all gathered information for the selected crops. In the scope of this ESA project, follow-up studies on plant growth chamber design and Equivalent System Mass (ESM) analysis were carried out.

Modern air vehicles face increasing internal heat loads that must be appropriately understood in design and managed in operation. This paper examines one solution to creating more efficient and effective thermal management systems (TMSs): vapor cycle systems (VCSs). VCSs are increasingly being investigated by aerospace government and industry as a means to provide much greater efficiency in moving thermal energy from one physical location to another. In this work, we develop the AFRL (Air Force Research Laboratory) Transient Thermal Modeling and Optimization (ATTMO) toolbox: a modeling and simulation tool based in Matlab/Simulink that is suitable for understanding, predicting, and designing a VCS. The ATTMO toolbox also provides capability for understanding the VCS as part of a larger air vehicle system. The toolbox is presented in a modular fashion whereby the individual components are presented along with the framework for interconnecting them.

A rigorous study of physical phenomena that characterize the energy transfer in a radiative panel, presents serious problems when, aiming at optimizing feasible design solutions, is oriented to the prognostic evaluation of the overall system performance. Different thermal interaction modes among constitutive components (i.e. headers, tubes, fins, honeycombs) and an intrinsically complex geometry make extremely cumbersome, if not impossible, to operate with a mathematical model featuring infinite degrees of freedom, as is the case for the real system. The need thus arises to build up a model possessing limited degrees of freedom, capable of approximately portraying, yet with specifiable accuracy, the bulk of physical phenomena that actually evolve in the heat rejection system. In the given frame this work elucidates how the objective may be attained by utilizing the finite element method and how it is also possible to deal with non-linearities stemming from existing boundary conditions.

As the cost and complexity of modern aircraft systems increases, emphasis has been placed on model-based design as a means for reducing development cost and optimizing performance. To facilitate this, an appropriate modeling environment is required that allows developers to rapidly explore a wider design space than can cost effectively be considered through hardware construction and testing. This wide design space can then yield solutions that are far more energy efficient than previous generation designs. In addition, non-intuitive cross-coupled subsystem behavior can also be explored to ensure integrated system stability prior to hardware fabrication and testing. In recent years, optimization of control strategies between coupled subsystems has necessitated the understanding of the integrated system dynamics.

New technologies, evolving customer requirements, different process procedures, part changes, inequities between CAD model and actual fixtures and parts, and other problems all require a flexible process environment. However, increased process complexities place a burden on production operators. CIMCORP has developed a flexible environment for drilling, routing and waterjet cutting composites. The system accepts off-line CAD/CAM generated part programs, allows on-line creation and editing of programs, integrates customer expertise to help optimize production, yet maintains a simple production level environment. The environment utilizes pop-up menus and pull down interaction windows to reduce operator input to known values. An on-line RS-274 editor, communication with intelligent peripheral devices, and system administration screens for reconfiguration of process parameters are also included.

A method for thermally analyzing convectively cooled flight experiments is presented in this paper. A three-dimensional fluid flow analysis code was used to optimize air circulation patterns and predict air velocities in thermally critical areas. A comparison between a fan flow analysis using this code and the performance characteristics of a typical isothermal free jet was made. The velocity profiles and radial distribution agree well for downstream mixing of the flow. Predicted air velocities from the fluid analysis were used to calculate forced convection coefficients for the flight experiment. These convection coefficients were used in a finite difference thermal analysis code to describe the response of air temperature and heat loss for the LIDAR Atmospheric Sensing Experiment (LASE) during transient flight profiles. The performance of the existing thermal design is described and the analytical techniques used to arrive at this design are presented.

The present study aims at the implementation of a Matlab/Simulink environment to assess the performance (thrust, specific fuel consumption, aircraft/engine mass, cost, etc.) and environmental impact (greenhouse and pollutant emissions) of conventional and more electric aircrafts. In particular, the benefits of adopting more electric solutions for either aircrafts at given missions specifications can be evaluated. The software, named PLA.N.E.S, includes a design workflow for the input of aircraft specification, kind of architecture (e.g. series or parallel) and for the definition of each component including energy converter (piston engine, turboprop, turbojet, fuel cell, etc.), energy storage system (batteries, super-capacitors), auxiliaries and secondary power systems. It is also possible to setup different energy management strategies for the optimal control of the energy flows among engine, secondary equipment and storage systems during the mission.

A generic engineering trade study methodology has been developed to provide an effective framework for the system analysis of regenerative live support systems. The performance of engineering tradeoffs is a key technique in a rigorous system engineering process that is being used to develop advanced regenerative life support technology at NASA Ames Research Center. The trade study methodology consists of the following steps: 1) deriving relevant life support system functional requirements from a given space exploration mission scenario of interest; 2) developing a tradeoff decision methodology consisting of a set of evaluation criteria and corresponding weighting functions grouped into a relational hierarchy; 3) synthesizing a set of design options to be evaluated during the study; 4) modeling and analyzing each design option to generate data to input to a quantitative scoring scheme; and 5) evaluating each design option using the information developed in the preceding steps.

In this study, the authors concluded that a super energy-efficient vehicle (SEEV) with fuel economy more than 100km/liter could be possible with the present technology level. The new environmentally-compatible vehicle was designed to mitigate urban warming, air pollution and CO2 emissions in the urban area. The authors evaluated optimal specifications of the new concept energy-efficient electric vehicle (EV) equipped with flywheel and photovoltaic (PV) cell and also reported the results of the running simulations for the proposed vehicle. The proposed SEEV will be very promising to mitigate urban and global warming, and toconserve fossil fuel consumption.