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The tandem rotor configuration is particularly convenient for the lift-compound approach in helicopters. In fact, the additional wing is positioned between the two rotors in an area that is marginally interested by the airflow in vertical flight. On the contrary, in horizontal flight, the airflow accelerated by the frontal rotor directly invest the wing improving its lift. A very thin wing with a short chord and a relatively large span can be manufactured with the same technology of the rotor blades. If this wing is fixed without control surfaces, the additional weight can be extremely limited. A concaveconvex high lift airfoil can be used. This airfoil is relatively stiff due to the large bending moment of inertia. A skin stressed structure can be used for the additional wing to obtain also a large torsional stiffness. This lightweight wing can be installed on the helicopter when required and it can be optimized to a defined flight condition. In our case the optimization was performed for cruise. With a very limited weight increment and with a lift penalty within the simulation approximations, the cruise fuel consumption can be halved. The result is impressive for ferrying and long range passenger transport operations, where load capacity can be fully exploited only by increasing the fuel load. In this case a helicopter like the Chinook can perform long range missions with a significant increase in operational capability.

CRDID (Common Rail Diesel Engine) main advantage is the extremely high efficiency (up to 52%), the enormous amount of hours run and the flight readiness. Moreover, diesel fuel is safer than jet fuel and it is available everywhere. Therefore, refuelling flights to airports or dedicated supply lines can be avoided. However, diesel engines are generally heavier than turboshafts and require an additional cooling system. This requirement is particularly stringent during near stationary operations of the helicopter. In fact, if fans are used for the cooling system, the available power is reduced with an increased penalty weight for the installation. For this reason the ejector exhaust system can be successfully used in CRDID powered helicopters. A feasibility study of the cooling system for a CRDID (Common Rail Diesel Engine) on a common light helicopter (Eurocopter EC 120-class) is introduced. Optimization of this system is performed. The total mass available for the CRDID is evaluated starting from fuel consumption and helicopter data. A derivative of an automotive engine is proposed for the turboshaft replacement. The result is that the ejector exhaust (augmenter) is extremely effective. Solid Works Flow Simulation confirms the ejector choice and the design criteria.

The new RPAS (remotely piloted aerial systems) are mostly video cameras with wings whose ownership isn't enshrined in any constitution. Rulers are rushing to do regulate the lack of safety and accountability for RPAS. In Italy ENAC (aviation authority) legislated against random acts of stupidity and probable failures. For the current year of 2015, there is a forecast to sell $1bn worth of RPAS product. For these reasons the installation of RPS (Recovery Parachute System) on commercial RPAS is particularly interesting. A few RPS manufacturers have manufactured specific RPS systems for "drones" both rotary and fixed wing. However, these systems are designed with the same criteria of manned aerial vehicle. This paper demonstrates that the design criteria of RPAS are sensibly different from other applications. In particular the rate of descent during recovery should be reduced from 6m/s to 2m/s. This fact poses new challenges in parachute design. In fact RPS mass depends on parachute diameter that increases with low descent rates. This paper demonstrates that it is possible to design effectively RPS for RPAS up to 80kg by using nonwoven fabric in parachutes. In this way the RPS mass is a small fraction of the RPAS one. Deployment systems are not a problem for RPAS since masses are extremely small and the power necessity are accordingly limited.

Many papers for the analytical solution of the lift distribution on a semi in semi-elliptical wing have been published. These works [1] usually approximate the solution by series expansion. This paper introduces an original method for the closed-form solution of this problem. The solution is possible through the use of symbolic manipulators. The wing of the WWII fighter "Reggiane Re 2005" has been solved analytically with the proposed method. The results are similar to the ones obtained by the panel-method and CFD. A CFD simulation of the Re 2005 at maximum speed demonstrates that these results are reasonable.

In hypersonic aircrafts, the necessity of operating at speed lower than Mach 1.0 obliged the designers to use the complicate propulsion plant of the mixed compression turbojet. Fast commercial passenger transportation will probably shorten the flight time by a factor 5, from the actual 6 hours to 1 hours for the London-NYC flight route. Therefore, the engine will work for a shorter time. The subsonic part of the flight is very limited. For this reason, a possible solution can be to substitute the turbojet with a pulsejet in the ramjet duct. Valveless pulsejets are extremely, simple, reliable, lightweight, fully throttable jet engines. The main limitations of the pulsejet are very low efficiency, relatively low "thrust density" and noise. Noise is naturally reduced as the main working frequency passes from the 150Hz of small pulsejet to the 40Hz of larger ones. Efficiency can be increased inserting the pulsejet in a ramjet-duct. This solution increases the pressure at the pulsejet intake and efficiently recovers heat from the pulsejet walls. Finally, it is possible to decelerate the jet with an ejector exhaust thrust augmenter. The feasibility of this concept is investigated in this paper. For this purpose, it was imagined to develop a transport aircraft with the aerodynamic of the Valkyrie and the new propulsion system. A cruise speed of MACH 3.5@25,000m was simulated with CFD. In this cruise condition the pulsejet works as a combustion stabilizer for the ramjet. Also, the take-off condition was simulated. At take off the thrust is obtained only by the pulsejet.

Aircraft fuel consumption depends on engine, engine installation, propeller and aircraft efficiency. The matching of the installed propeller is optimized for a design point and it is a compromise for the other working points. The matching of aircraft optimum lift/drag, the minimum engine fuel consumption and the maximum propeller efficiency is rarely achieved. The hyper simplified model on books does not reach the result. Practically very few aircrafts truly match the three conditions The champion of matching are current airliners that, at least in cruise and with half the fuel, reach the optimum at least at the nominal density altitude. In addition, a few fighters and record aircrafts also achieve the maximum possible speed at the nominal conditions. The large majority of the general aviation aircrafts are far from the optimum matching. Even Unmanned Aerial Vehicles are not champions of propulsion efficiency. Ultralight and sport aircraft are the worst. Turbines are very difficult for matching since their optimum efficiency is reached in a very limited working area. Even spark ignition engines are not efficient in off-design conditions. In fact, the spark ignition engine works with an air to fuel ratio by mass that can ran from 16:1 (lean mixture) down to 12:1 (rich mixture). Even spark ignition direct injection engines the combustion takes place within this range. At the relatively high torque settings typical of aircraft engines, the air inside the combustion chamber is burnt entirely and the power output depends on the engine volumetric efficiency. In diesel engines, the air inside the combustion chamber is never burnt entirely. The minimum air to fuel ratio is around 17:1, but the engine works well with any air to fuel ratio below this value. This means that CRDID (Common Rail Direct Injection Diesel) efficiency or BSFC (Brake Specific Fuel Consumption) curve is flatter than the spark ignition engine one. This fact gives a decisive advantage in the propeller matching and in the fuel consumption. In fact, off-design performance is the strongest point in favour of CRDIDs in general aviation. Therefore, the fuel consumption of CRDID takes advantage not only from the extremely high efficiency of the engine, but also from the better matching. In fact, it is possible to map the CRDID FADEC (Full Authority Digital Electronic Control) to optimize SFC (Specific Fuel Consumption). In the example shown in this paper, a CRDID needs nearly half the fuel necessary to a very good spark ignition engine.

Composite structures such as CFRP offer significant weight reduction over the conventional aluminum alloys for aircraft. Weight reduction improves fuel efficiency of the aircraft by approximately 20% which results in cost savings and simultaneously reduces the operational environmental footprint. However, the new aluminum-lithium alloys offer significant improvements and are viable alternatives to CFRP. Aluminum lithium alloy 2195 with Friction Stir Welding is introduced as a successful alternative to CFRP primary structures. A "thick skin" monocoque design with integral stringers as crack stoppers is discussed. An old Macchi 205 WWII fighter plane has been redesigned both in CFRP and 2195-FSW for comparison. The final designs are comparable in weight, but 2195-FSW is more competitive based on mass production costs, reparability, and environmental impact. Macchi 205 airplane is used due to in-depth experience with the original aircraft geometry and loads. Knowledge gained here can be directly transferred to larger structures, from corporate jets to large transport category airplanes [1].

This paper introduces a method to simplify a nonlinear problem in order to use linear finite element analysis. This approach improves calculation time by two orders of magnitude. It is then possible to optimize the geometry of the components even without supercomputers. In this paper the method is applied to a very critical component: the aluminium alloy piston of a modern common rail diesel engine. The method consists in the subdivision of the component, in this case the piston, in several volumes, that have approximately a constant temperature. These volumes are then assembled through congruence constraints. To each volume a proper material is then assigned. It is assumed that material behaviour depends on average temperature, load magnitude and load gradient. This assumption is valid since temperatures varies slowly when compared to pressure (load). In fact pressures propagate with the speed of sound. The method is validated by direct comparison with nonlinear simulation of the same component, the piston, taken as an example. In general, experimental tests have confirmed the cost-effectiveness of this approach [1-4].

In fixed wind turbine installations, the optimal wind location is difficult to individuate, permissions are difficult to obtain and the production site is distant from the costumers. The large production scale of small wheeled wind turbines keep the cost at minimum and give the possibility to install the windmill close to the final costumers. CFD simulation makes it possible to optimize the matching of a small mobile wind turbine with an automotive commercial alternator. This paper proposes an innovative device to furl the wind turbine around the pole axis in such a way to optimize energy production and avoid over-speed. For this purpose a commercial shock-absorber and a cam mechanism are used. The CFD simulation, in this case with Flow Simulation of Solid Works, makes it possible to design the turbine, the tail vane and the mechanism to maximize energy production. The device includes a shock absorber and a cam mechanism. The system provides optimum matching of the turbine torque output to the generator shaft. The same mechanism also determines the cut-out speed. The automotive generator includes a system to charge a 24V standard battery. Then, a power inverter outputs the electric energy to the grid. The 4m-diameter three-blades-rotor is connected to the 3.6kW automotive alternator through a commercial 2.5:1 speed multiplier.

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. The mechanical energy from the diesel and from the turbine powers the compressor and the fan. The system can be seen as a turbocharged diesel engine with the turbocharger that outputs energy to the turbofan, increasing the output power and or the efficiency. A diesel-turbine compound can be realized in this way. The coupling of the two systems may be obtained in several different ways. The simplest is to put on the same shaft the compressor, the diesel crankshaft and the turbine. In front of the compressor a speed reducer drives the fan. A second example is to connect the turbine and the diesel on to electric generators. Electric engines are connected to the compressor and to the fan. The traditional turbodiesel has the compressor coupled to the turbine, and the diesel engine that moves the fan. In this latter case, however, the turbine does not energize the fan. Many other hybrid and nonhybrid solutions are possible. The problem is to optimize temperatures, pressures and rpm to the different machines that form the compound. The availability of many experimental data for diesel and turbines makes it possible to obtain a design of a "true" feasible optimum Diesel-Brayton cycle. This efficiency figure justifies the huge manufacturing and development costs of these turbocompound engines [1-4].

CRDID (Common Rail Direct Injection Diesel), automotive derived engine, main advantage is the enormous amount of experimental data. These engines are produced in millions of units and reliability data based trillions of hours are available. It is also possible to run automotive CRDIDs with jet fuel. It is also possible to mix the two fuels with a proper ECU (Electronic Central Unit) mapping. Therefore, the necessity to refuel in airports can be eliminated. Moreover, the additional mass of CRDIDs is largely compensated by the reduced fuel amount necessary to exploit the same mission/flight. However, an additional cooling system duct should be added. For this purpose, fans are replaced by ejector exhaust (augmenter) that does not need fan additional power. Solid Works Flow Simulation confirmed the feasibility of an ejector-exhaust-powered cooling. However, pressure fields around the helicopter varies in a very significant way in the different flight conditions. High cooling duct efficiency requires pressure and clean air at the intake port and negative pressure at the duct nozzle. Therefore, a optimization of the cooling duct positioning has been carried out on a common light helicopter (Eurocopter EC 120). Several different solutions have been simulated with Solid Works Flow Simulation. CFD confirms the ejector choice and the design criteria. The best configuration is a derivation of a Formula 1 intake duct. This solution proved to be the most effective for the CRDID-exhaust powered cooling duct. The result is that the ejector exhaust (augmenter) is extremely effective. With two small intakes at the side of the mast, the pressure differential between the intake and the nozzle of the duct proved to be extremely stable in every flight condition, even with crosswind.