Design methods for mobility

This work investigates the flexural behavior of a composite sandwich made of flax fibers reinforced skin facings and an agglomerated cork core, to be employed as an eco-friendly solution for the making of structural components of small sailing boats. An experimental mechanical characterization of the strength and stiffness flexural behavior of the proposed sandwich is carried out, providing a comparison of performances from three implemented assembling techniques: hand-lay-up, vacuum bagging and resin infusion. Sandwich beams have been tested under three point bending (TPB) at various span lengths. A procedure is also proposed and implemented to consider the potential influence of the local elastic indentation in the experimental evaluation of the flexural stiffness. This procedure is based on the analytical solution of an indented beam resting on a fully backed Winkler foundation.

Keywords: Agglomerated Cork Core , Composite Sandwich , Flexural Behaviour , Indentation , Long Flax Fibres , Winkler foundation

The high number of hull losses is a main concern in the UAV field, mostly due to the high cost of on-board equipment. A crashworthiness design can be helpful to control the extent and position of crash impact damage, minimizing equipment losses. However, the wide use of composite materials has recently put the accent on the lack of data about the behavior of these structures under operative loads, such as the crash conditions. This paper presents the outcome of a set of tests carried out to achieve a controlled crush of UAV structures, and to maximize the Specific Energy Absorption. In this work, a small-scale experimental test able to characterize the energy absorption of a Carbon-fiber-reinforced polymer under compression was developed introducing self-supporting sinusoidal shape specimens, which avoid the need for complex anti-buckling devices. The specimens were produced with different auto-triggering configurations and fibers' continuity was interrupted in selected position and for different extent in order to investigate the Specific Energy Absorption of the weakened laminates. The auto-triggering configuration was able to control the position of the initial failure of the specimen without any decrease in safety performance. This new kind of very light crash absorber can be used in small UAV to reduce the crash loads in the avionic and payload bay. With reference to a small UAV designed and manufactured at University of Bologna, an optimization of the crash absorbers positions has been carried out in order to achieve the best results in terms of energy dissipation.

The aim of this paper is to develop a new concept of unconventional airship based on morphing a lenticular shape while preserving the volumetric dimension. Lenticular shape is known to have relatively poor aerodynamic characteristics. It is also well known to have poor static and dynamic stability after the certain critical speed. The new shape presented in this paper is obtained by extending one and reducing the other direction of the original lenticular shape. The volume is kept constant through the morphing process. To improve the airship performance, four steps of morphing, starting from the lenticular shape, were obtained and compared in terms of aerodynamic characteristics, including drag, lift and pitching moment, and stability characteristics for two different operational scenarios. The comparison of the stability was carried out based on necessary deflection angle of the part of tail surface. The comparison results indicated that new shape concept possesses much better aerodynamic and stability characteristics and could be used for detailed optimisation studies.

Wind tunnel experiments are performed to investigate the aerodynamic characteristics of unconventional airships docking in-flight. The aim is to provide wind tunnel data for multiple feeders docking to a cruiser and to identify key issues in docking approach strategies. The conceptual design of a docking mechanism and its integration into a baseline configuration is also addressed. Force and moment data are collected on a 1:7.5×10-4 scale model for the cruiser configurations and at various cruiser-feeder vertical separation distances to simulate docking. Results indicate that the there is a trade-off between drag performance and the implementation of the docking mechanism. Drag decrease is measured when the modified cruiser is docked with the feeders. Best docking practices are also identified from the pitching moment coefficients showing that the cruiser-feeder can be trimmed during docking.

The monitoring of vital parameters for athletes of all disciplines is becoming more and more essential, to improve performances and to ensure a constant control of athletes' physical conditions, thus preventing health risks and injuries. However, especially in amatorial competitions, the low available budget limits leads to the use of inexpensive and thus ineffective instrumentation. In this paper, a low-cost system, based on a commercial smartdevice, for monitoring purposes in the context of amatorial car races is proposed. A single-lead electrocardiographic trace, body temperature, and driver acceleration profile are simultaneously acquired, locally stored and preprocessed, and periodically sent to a cloud service, allowing data sharing and remote processing. Experimental tests operated by means of a Formula SAE car in a test track have demonstrated the effectiveness of the proposed approach for the acquisition of important data to evaluate the degree of stress of a driver during the race.

Keywords: amatorial car race , smartphone-based system , Vital parameters monitoring

The new trends in the design of race catamarans has introduced new innovations as huge vertical wings instead of main soft sails, and foiling underwater wings. The scope of the paper is the development of a mathematical model of these new features to be implemented in a simulator designed for training purpose. The paper describes the principal assumptions, the simplifications, and the modeling strategies that were adopted in order to obtain a real time simulation. The mathematical model is implemented in an already existing SIMULINK simulator developed at the University of Southampton and exploits its graphical interfaces. The main new feature is the “flying” simulation. The simulator is designed to interact with the in-training team and to feedback the crewmen with realistic cues. Beside training purpose, the simulator could also be a useful tool in comparing different race strategies in order to select the most promising one.

Keywords: America's cup , Crew training , Human interface , Real-time , Sailing simulator , Simulator

In order to optimize the design of the thermodynamic cycle of a turbine (Brayton cycle) for using modern common rail as an “active” combustion chamber, it was intended to write the present paper. About the present case, the “active” combustion chamber produces a large amount of the mechanical energy that drives the fan. The incoming air is compressed by the compressor, then it is refrigerated and inputted in the diesel engine. A high pressure common rail system optimizes the combustion in the diesel combustion chamber and the expansion begins inside the diesel engine. At the exhaust of the combustion chamber, a turbine completes the expansion of the hot gases. A nozzle accelerates the exhaust from the turbine to increase the overall thrust.

Keywords: Aircraft , Diesel engines

Back to the 1997 when this activity began, it was generally though that CRDIDs (Common Rail Direct Injection Diesel) would have completely replaced the piston gasoline engines used in aircrafts within a decade. This fact did not happen for several reasons. This paper tries to individuate these reasons. The more updated solutions to the many problems that almost stopped this application are also introduced. In this third part, maintenance and cost effectiveness related issues are introduced. Automotive OBD concept is described as a method to reduce maintenance costs and risks.

Keywords: Automotive and aerial-vehicle , Common rail direct injection diesel , On board diagnostic (OBD)

Electric turbocompounding in racing spark ignition engine is focused on transient operation. Classical compressor and turbine maps should be adapted for this particular condition. Electric turbocompounding has limited torque and power available on the electric side. For this reason, an ad hoc solution should be devised. A low inertia solution is proposed in this paper with the advantage of minor modifications on existing commercial highly optimized turbochargers. A large advantage over the current solution may be achieved. In this solution, a very low inertia electric/motor generator is magnetically coupled to the turbocharger on the compressor side of the shaft. The electromagnetic coupling acts also as a torque limiter allowing extremely large slips between turbocharger and generator shafts.

Keywords: Electric turbocompound , Spark ignition engines

Piston engines with power up to 1000HP (735.5 kW) are becoming popular in the aeronautical field for the high efficiency and the possibility to work with Diesel, jp4 and jp8 fuels up to altitudes up to 20,000m (65,000 ft). This paper updates a secondary advantage of piston engines: the Meredith effect. The Meredith duct is a ramjet powered by the heat wasted in cooling. In this way the efficiency of the original piston engine that can be higher than 50% which is the normal in common rail diesel engines. Even if the efficiency of this ramjet is lower than 30%, an accurate Design of this secondary engine can add a significant amount of thrust to the fan or the propeller powered by the piston engine. This effect, well known since the beginning of WWII, is being thoroughly analysed in this paper with regard of the efficiency. Previous papers introduced and a new radiator, with wing section tubes. As it will be seen the main design variable for the Meredith ramjet it the air temperature increase. This paper demonstrates that it is not convenient to increase this temperature over 200°C for aircrafts flying at about 600km/h@6000m (~330knots@20,000ft). The in-wing duct appears to be slightly better than the in-fuselage or the in-nacelle ones.

Keywords: Piston engine cooling

Back to the 1997 when this activity began, it was generally thought that CRDIDs (Common Rail Direct Injection Diesel) would have completely replaced the piston gasoline engines used in aircrafts within a decade. This fact did not happen for several reasons. This paper tries to individuate these reasons. The more updated solutions to the many problems that almost stopped this application are also introduced. In this second part of this paper engine selection concepts and TBO (Time between Overhaul) are introduced.

Keywords: Avionization , Conversion , Diesel common rail

Back to the 1997 when this activity began, it was generally thought that CRDIDs would have completely replaced the piston gasoline engines used in aircrafts within a decade. This fact did not happen for several reasons. This paper tries to individuate these reasons. The more updated solutions to the many problems that almost stopped this application are also introduced. In this first part FADEC related issues are introduced. Torsional vibration control is also briefly discussed.

Keywords: Aeronautical engines , Conversion of automotive engines , Diesel engines

Common rail automotive (Direct Injection) Diesels (DID) are always turbocharged. This engine works at limited altitude and should output torque at low rotational speeds. Not so for engines that work coupled to propeller and fans. This is the case of aircraft and helicopter engines. In this case it is important to have high output power at high rpm and to keep throttle authority and power at the higher altitude possible. Some basic concepts to achieve this result are introduced in this paper. Single turbocharging systems are introduced and an option to improve the altitude performance is discussed. Far from being exhaustive, this paper is an initial step in the long and awkward technology of turbocharging automotivederived engines. The basic concepts for efficiency are also discussed.

Keywords: Common rail automotive Diesels (DID) , Turbocharging

This paper analyzes the design process of an aircraft propeller for a piston engine. The propeller should also damp the main critical torsional frequency of the crankshaft. The first step was the calculation of the geometrical parameters of two different blades: one according to Larrabee's procedure and the other one according to the Theodorsen's theory. The evaluation of the effect of aerodynamics and centrifugal loads has required the union of the results come from CFD (Computational Fluid Dynamics) and the ones come from the CSM (Computational Structural Mechanics), through the execution of several one way FSI (Fluid Structure Interaction) analyses. The results allowed making pre-stressed modal analyses, which gave the opportunity to identify the kinds of propeller having the fundamental frequency coincident with the main resonance frequency of the crankshaft. The final design is a blade having the deformed shape of the optimum aerodynamic design.

Keywords: Aircraft propeller , Crankshaft , Torsional vibrations , Tuned damper

Multiple-speed gearboxes with computer controlled automatic gear selection devices are a common possible choice in cars. Robotized gear insertion of one tenth of a second is possible. Economical and weight consideration are to be made to verify if it is convenient to use a smaller engine and a larger gearbox with a wider choice of speeds. In this paper, an automotive application for a public transport vehicle based on a Class S chassis with the choice of common-rail direct injection engines. This choice is particular unfavorable for the multispeed gearbox since common-rail engines have very flat specific fuel consumption curves. The lumped mass model implemented is conceived to estimate velocity, acceleration and fuel consumption starting from aerodynamic, inertia and thermodynamic data of the vehicle. The estimated data of performance and fuel consumption were compared with measured values. A Genetic elitarian Algorithm (GA) was used to optimise the engine choice and the gearbox speeds distribution. A maximum reduction of 15% was then calculated with a 16-speeds gearbox and a 140 HP/300Nm engine in comparison with the standard 5-speeds 204 HP/500Nm engine. This fuel reduction was obtained on the mixed city-motorway cycle. In this case, maximum speed is limited to 180km/h and the 0-100km/h acceleration is reduced to 11s (from the original 8.6s). The weight remains almost unaltered since the 204 HP engine is heavier than the 140 HP and this largely compensates the gearbox weight increase. The multiple speed solution seems to be very interesting also for public transports vehicles and for trucks.

Keywords: Automatic selection system , Automotive , Multiple-speed gearbox

Starting from a good automotive engine is always a good idea, also for brand new automotive design. In the case of automotive to aircraft conversions, the automotive engine is modified as little as possible. This approach has several advantages: reduced development time, good reliability and availability of cheap and worldwide spare parts. What it may appear a good idea is to tune up the original ECU (electronic control unit) by using one of the several softwares available on the market. However, this approach is not feasible even for ultra light aircrafts. This is due to the lack of control on the software of these ECUs. In fact, automotive software timing or ECU set-up is performed in the following way. The final ECU manufacturer (who holds the responsibility of the hardware and the software in the final car ECU) supplies to the car manufacturer a “development ECU” with a “development Software”. This system is tuned on the engine and on the car to fulfill the car manufacturer requirement. When the tuning is considered satisfactory, the “maps” (the data inputted by the manufactured) are given to the ECU manufacturer. This later translates the data into the software of a “production ECU”, that is given back to the car manufacturer for final validation prior to serial production of ECU and car. In this case, even the car manufacturer does not have a full control of what happens inside his ECU. This is logical since the full responsibility is given to the ECU part supplier. So the tuning of a serial production ECU is more than a true programming. Results are unpredictable to a certain extent that depends on the level of knowledge of the person who performed the tuning and of the software house that implemented the software. The software that truly runs on serial production ECU is a well kept secret of the ECU manufacturer, since it is the knowledge of ECU. The simpler is the software the less expensive will be the ECU and the larger the profits of the ECU supplier. Tricks are hidden inside the ECU to obtain these results; these tricks multiplied per millions of ECU give the supplier a competitive advantage. So, even the car manufacturer has a limited control on what happens inside the real-time software of the ECU, what emerges is the engine and the car behavior. Aircraft conversions require the replacement of ECU, wirings and sensors with appropriate units. This assembly with its own software constitutes the aircraft FADEC.

Keywords: Aircraft , Diesel , Electronic control unit , Helicopters , Mapping optimization

All future power developments should consider as primary tasks the achievement of the required emission levels and CO2-values, while still providing optimum torque-to-rpm curves, the lowest SFC (Specific Fuel Consumption) over the widest range possible, good power-to-weight and affordable costs. One method to achieve these objectives is the downsizing. To achieve the levels of engine performance that are required, a significant increase in the rated speed and in the boost pressure is mandatory. In this case, the result is an increase in the flow rate through the intake and exhaust ports and valves. Considering the impact of these changes, the port layout of the system is reanalyzed. Another physical limit to the maximum speed depends on the CR (Common Rail) injector dynamic performances. These performances decrease with size for inertia problems and they depend on the amount of effort involved in their development. Automotive engines in the range of 10 to 100 HP per cylinder are the most common. For this reason, these injectors are the most advanced and costeffective. Furthermore, their small size and inertia is favorable to the best dynamic performance. The larger number of nozzles improves combustion performance. In fact the better surface to volume ratio or the spray improves heat transfer. For this reason, multiple injection systems can be used in the modern HSDI (High Speed Direct Injection) CR large diesels. This solution was commonplace before WWII, but has been progressively abandoned with the introduction of mechanical high-pressure injection systems and the bowl combustion chamber. In this paper, a dual combustion chamber per cylinder engine is considered. The primary purpose of this study is to examine the best port layout on a modern diesel combustion system and to introduce a new promising concept. The study included flow measurements of intake flow and CFD simulations of the flow field during intake. This design enables the formation of two homogenous swirls centered onto the injectors, with excellent flow coefficient. The design also allows an increase in volumetric efficiency combined with a reduction in flow losses.

Keywords: Diesel engines , Multiple injections , Multiple swirls

A feasibility study for the installation of a CRDID (Common Rail Diesel Engine) on a medium helicopter is introduced. The total mass available for the CRDID is evaluated starting from fuel consumption and helicopter data. A derivative of an automotive engine was considered. The installation of the new CRDID was then studied. The result was the evaluation of the power plant installation mass that proved to be lower than the maximum admissible. The installation is then possible. Care should be taken in the cooling system to avoid large penalties in power and efficiency. For CRDID powered helicopters, the ejector exhaust system can be successfully used. With CRDIDs, huge advantages can be obtained on operating costs due to reduced fuel consumption, safety and helicopter availability. In fact, diesel fuel is available everywhere and flights to airports just for refueling can be avoided.

Keywords: Common rail diesel , Helicopter power unit

It is shown that a CRDID (Common Rail Direct Injection Diesel) turbo compound design is a highly over constrained problem. Very few options are available to the designer, even from the metallurgical point of view. The process of the preliminary design is fully described and the preliminary performance evaluation is fully described. A comparison with the original turbo shaft installation of a Hercules C130J aircraft is performed and the results are analyzed. The CRDID turbo compound seems an extremely convenient option since it can halve the fuel consumption, with increased safety and reduced logistical problems. CRDID emissions, with SCR (Selective Catalytic Reduction) may easily reach the automotive Euro 6 standard.

Keywords: AE2100 , Common rail direct injection diesel (CRDID)

The Prolonged Autonomy e-bike o PA-bike is a e-bike that can use a traditional fuel to charge the battery during run or at rest. In this way it is possible to prolong the autonomy of the e-bike. A fuel cell with a reformer or a traditional very small catalyzed piston engine can be used. In both cases the emissions are very limited and the efficiency is very high, since the "traditional fuel" motors work at constant optimum condition. This paper tries to optimize the PA-bike by assembling commercial components. Outsourcing for bicycles should be very easy since commercial part availability is very high. Customization is a very common practice for bikers, since it does not require authorizations. However the problem proved to be over constrained. The commercial components, in particular the electric motor, proved to be an important boundary condition. The result is a single possible solution, or a category of solutions, all similar. This is due to the fact that commercial components are highly standardized for marketing reasons.

Keywords: Autonomy , E-bike , Optimization