ITAR20130041A1 - AUXILIARY PROPULSION SYSTEM FOR TAKE OFF AND VERTICAL LANDING OF AIRPLANES THAT USES RECHARGEABLE ENERGY STORAGE SYSTEMS - Google Patents

Description

TITLE: Auxiliary propulsion system for vertical take-off and landing of airplanes that uses rechargeable energy storage systems.

FIELD OF APPLICATION OF THE INVENTION

The present invention refers to an auxiliary propulsion system for piloted airplanes or UAVs (Unmanned Aerial Vehicles) with primary thermal engine based on one or more rechargeable energy storage systems capable of providing high specific powers for a sufficiently long discharge time. to be used with dedicated thrust generators, which give vertical thrust levels higher than the weight of the aircraft, so that it can take off and land vertically or almost vertically. In this broad sense, the total power system of the airplane is here defined as "hybrid" as it consists of at least one primary aircraft engine and additional non-endothermic engines that use stored energy in kinetic, electrochemical, electrical form.

BACKGROUND

One of the elements that most impact both economically and logistically and on the total travel time in the use of airplanes is the necessary presence of airports or airfields that must meet specific criteria and be suitable for the type of aircraft that must use them.

In particular, the length of the runways is very binding, which is a function of various environmental parameters (height above sea level, windiness, ...) and specific to each aircraft (speed, weight, ...) and that in any case, even in the case of small touring aircraft , is never less than a few hundred meters. Furthermore, typically light aircraft capable of operating from confined spaces require large wing surfaces and therefore have low cruising speeds.

The take-off / landing surfaces are generally quite distant from homes, offices or other points of interest for the traveler and therefore lead to an extension of the travel time, penalizing the fast cruising and economy characteristics of air vehicles.

In parallel, for UAVs (Unmanned Aerial Vehicles) that exceed a reasonable weight to be launched by hand, a suitable surface for take-off and landing is not always available. Hand-launching light UAVs also often have a similar problem on landing.

At the same time, helicopters, aircraft with a vertical thrust / weight ratio higher than one that allows them to take off and land vertically without the need for runways and airports, have not spread massively because they have very high acquisition and operating costs. In fact, the rotor or rotors with which they are equipped (propellers with two or more blades), in order to effectively carry out the support and translation, require, in addition to various constructive devices, mechanisms for the rotation of the blades along their axis and for the inclination of the rotor plane with the continuous and cyclical variation of their pitch, which require precision mechanisms highly stressed with fatigue which therefore entail high overhaul and maintenance costs. Furthermore, the power of the engine (s) (reciprocating or turbines) is relatively higher than the airplanes because they must guarantee a thrust higher than the weight while in cruising conditions the typical aerodynamic configuration of the rotor limits its operating speed and worsens its consumption per kilometer by limiting it. hence the range of action. The rotor also needs to be connected to the propeller by means of a large reduction gear and a long transmission stressed by a very high and pulsating torque. Helicopters are therefore used when there are no alternative means or in any case when there are no cost problems. In essence, the helicopter, in order to operate and take off / land vertically, has high production and maintenance costs while it cannot have the speed, efficiency and autonomy of airplanes of comparable cost.

To overcome some of these difficulties, vertical take-off aircraft have been built over the years for both civil and military uses. This experimentation started in the 30s for the helicopter and in the 60s for VTOL (Vertical Takke-Off and Landing) jet aircraft and tiltrotors with internal combustion engines has had modest successes despite a very high cost in terms of human lives. and loss of investment. The VTOL / STOL (Short Take-Off and Landing) airplane did not spread much due to very high operating costs and consumption. Apart from the helicopters, only some military VTOL and Convertiplani aircraft are operational: the Harrier AV8B and recently a version of the new F-35 (F-35B capable of short take-off and vertical landing both with jet turbofan engines) and the Bell Boeing V 22 Typical Osprey tiltrotor with rotors capable of maneuvering even in stationary flight (albeit with various limitations compared to a conventional helicopter) while a civil tiltrotor is still being tested, the Agusta Westland AW 609, already in testing for some years and of which it is certification expected in 2016. In addition to extremely high operating costs, all these machines have some critical issues for normal civil use that make certification problematic and in any case extremely expensive.

Briefly, the production of a sustaining thrust greater than the weight is reduced between the choice between extremely powerful endothermic engines, relative to cruising requirements, which accelerate a relatively limited air flow rate to very high speed through a certain number of small nozzles and the choice of accelerating a very large air flow by accelerating it with a modest increase in speed by means of a moderately more powerful engine than that typical of a conventional aircraft of the same total weight. The first solution is typical of VTOL aircraft while the second is typical of helicopters. Tiltrotors represent an intermediate solution with large steerable propellers with somewhat higher disc load than helicopters in order to allow moderate cruising speeds.

While in helicopters the area of the propulsive flow (area of the rotor or rotors) is very high and the dynamic pressures generated by the rotor are usually between 10 and 40 Kg / m2 (98-392 Pascal), which allow excellent propulsive efficiency (i.e. low values of installed power with respect to the weight of the aircraft) in convertiplanes the propulsive areas are reduced and the pressures vary between 70 and 150 Kg / m2 (680-1470 Pascal) with a reduction in propulsive efficiency particularly at low speed where, for more maximum vertical thrust is required. And in vertical take-off aircraft, with thrust obtained from the jet of the engines, the flow areas are limited and the pressures reach values of 1 kg / cm2 (100 kPascal) with extremely modest propulsive efficiency, particularly in low or zero speed operations.

It is clear that if there were the availability of vertical take-off aircraft with acceptable and extremely safe and reliable purchase and management costs, they could spread rapidly.

It should also be noted that, unlike a helicopter, a tourist or light transport aircraft capable of operating from very small surfaces is not required to be fully operational in hovering (e.g. to rescue shipwrecked people or mountaineers in difficulty or for operations with loads hanging, as with a helicopter) but they are only required to be able to land and take off safely from small surfaces and that this phase, which can also be managed automatically by an adequate guidance system, in which a strong vertical thrust is required , is limited to a few tens of seconds and requires a modest surplus of energy (a few KWh) while requiring considerable power for a short time. It should also be noted that currently flying tiltrotors, although they can operate in hovering flight, are not suitable for the recovery of people in difficulty or things with a winch due to the excessive violence of the jet of the rotors, much higher than that of a helicopter. The same goes for UAVs with VTOL capability even with much lower energy storage requirements.

Recent technological developments in the field of batteries, capacitors and inertia wheels appear to make it feasible and convenient to use high energy density (Wh / kg) storage systems that can also give the high power required by airplanes to generate the thrust required in the vertical take-off and landing phases. These systems can be recharged by the aircraft's thermal propulsion system, by an on-board auxiliary generator, by ground-based generators or by the network using suitable adapters.

Sectors that promote a lively development of these technologies are the competitive car industry and in particular Formula 1 or endurance speed races such as the 24 Hours of Le Mans and the renewable energy sector.

In fact, in recent years, KERS (Kinetic Energy Recovery System) systems have been developed for cars with a very high power / weight ratio that allow to recover part of the kinetic energy generated during braking to then return it in the acceleration phases, increasing it thus performance and at the same time decreasing consumption. A substantial boost to this technology has been given by Formula 1, where since 2009 it is possible to use KERS with an additional maximum power of 60 kW for 6.6s.

There are some types of KERS; the electric one with batteries and / or capacitors (Ultracapacitors), the mechanical one with flywheel and CVT (Continuos Variable Transmisssion), and the electromechanical one with flywheel and high-speed electric motors / generators that differ in how the energy is stored and returned.

As mentioned, in addition to batteries and flywheels, capacitors or combined coil and capacitor systems can also be used as storage systems. In particular, according to a DOE / EPRI (Department of Energy / Electrical Power Research Institute) publication, Electricity Storage Handbook of July 2013, current technologies for high power and energy densities are in addition to High Speed flywheels , the new capacitors based on nanotechnologies (Nano Supercapacitors), the new Lithium batteries (Li-Ion, Li-Air) or in general the metal-air batteries (Metal-Air)

In view of the new F1 regulation for 2014, recovery systems called ERS (Energy Recovery System) have already been developed capable of producing 120 kW for 33s, that is, storing approximately 1.1 kWh of energy, 10 times greater than the "old" KERS of the current regulation.

These new ERS weigh about 8 kg, allowing power density of 15 kW / kg, and have the possibility of recovering, in addition to the mechanical energy of braking through a unit that is now called MGUK (Motor Generator Unit - Kinetic), also part of the thermal energy dissipated by the heat engine, through a unit called by analogy MGUH (Motor Generator Unit - Heat).

The renewable energy sector also requires energy storage capacity to increase the usefulness of renewable energy sources, typically discontinuous, such as solar and wind generators. Such systems must have large storage capacities at moderate costs, guaranteeing excellent performance and low operating costs for many cycles and for many years of service, for this purpose a lot of research is underway and systems with excellent characteristics are being defined.

Battery performance is improving over time while rapid and radical progress is expected both in mechanical storage systems that use flywheels in special materials and reversible electric machines capable of very high speeds and in storage systems based entirely or in part on new ultracapacitors. generation.

Using these rechargeable, kinetic and / or electrical / electrochemical elements and matching them appropriately to both the engine part of the airplane (to derive the energy required for charging before takeoff and before landing and also part of its power during the initial phase take-off and final landing) and to the operating one (transfer of energy, through impellers of fans, compressors or blowers and / or propellers, to the surrounding air, accelerating it and making it flow in the desired direction or directions) it is possible to obtain the necessary propulsive thrust, higher in modulus than the weight of the aircraft, for the time necessary for the vertical take-off and landing of the aircraft, also guaranteeing excellent ability to control the attitude and movements along the three axes, thus eliminating the need for a conventional airport.

The quantities involved are already compatible with the use at demonstration level of the current energy storage systems developed in competitive motoring which are capable of providing the auxiliary power required for the vertical or ultrashort take-off and landing phases of aircraft from light transport and / or UAVs.

In addition, the ongoing activity both in the automobile sector and in the renewable energy sector is leading to mass-production and therefore cost-effective construction of elements such as batteries, capacitors, flywheels, magnetic bearings and high-speed motors / generators. Several manufacturers are already proposing products which are very suitable for use in the present invention. As an example, SKF is marketing both magnetic bearings and a permanent magnet reversible electric motor for speed ranges up to 70,000 rpm.

SUMMARY

The present invention refers to an auxiliary propulsion system for airplanes equipped with a traditional primary engine, piloted or UAV, which will be called RAPS (Rechargeable Auxiliary Propulsion System) based mainly on rechargeable high-density energy storage devices and which can provide high power per unit of weight, which consists of:

• a storage section with one or more RRSU (RAPS Rechargeable Storage Unit) rechargeable energy storage devices both in kinetic form (flywheels), and in electrochemical or electrical form (batteries and / or super-capacitors). An accumulation section can also consist of a combination of the various types of units;

• a recharging section consisting of one or more RRU devices (RAPS Recharge Units) capable of deriving mechanical energy from the airplane engine or from auxiliary turbines, electrical energy from the airplane engine, from external generators, from photovoltaic cells, from the network o from the recovery of thermal energy from the primary heat engine;

• One or more RTG thrust generators (RAPS Thrust Generator) capable of transforming the energy supplied to it into an acceleration of an air flow to obtain a total thrust greater than the weight of the airplane. The RTG units will essentially be propellers and / or fans also ducted and / or counter-rotating and will have sufficiently high flow areas to ensure good propulsive efficiency, they will be placed in the most convenient positions of the aircraft and can be both fixed and deployable in the phases take-off and landing and then be folded and / or screened by suitable hatches at the end of these phases in order not to penalize the aerodynamics of the aircraft during normal flight phases. The airplane will therefore have a take-off and landing configuration with the RTGs open and / or deployed and a cruise configuration with the RTGs closed and / or folded. The propulsive flow of each RTG can be oriented around axes parallel to the pitch axis of the airplane and / or modulated in module in order to generate the desired total thrust and the rotation torques around the pitch, roll and yaw axes to control the aircraft attitude and its trajectory. Given the lightness and compactness of its components, the RTGs can be driven by a double motor and possibly be counter-rotating, and connected to the motors in order to tolerate engine failure and have negligible reaction torques. The RAPS system will also allow you to interrupt the landing or take-off maneuver at any stage and bring the aircraft back to safe operating conditions. The thrust generators can be either of the mechanical type activated by means of a motor shaft, or of the electric type and therefore activated by a dedicated electric motor.

An RCU (RAPS Control Unit) control section consisting of all those elements necessary to manage the system in total autonomy and / or partial and / or total direct control of the pilot which include sensors and actuators for:

o switch from the cruise configuration to the take-off and landing configuration,

o check the attitude of the aircraft and its trajectory during take-off and landing,

o switch from take-off and landing configuration to cruising configuration,

o monitor and charge the RAPS storage units.

An APTOL (Assisted Precision Take Off and Landing) system can also be provided to which the pilot can superimpose moderate changes or corrections and, if necessary, abort the assisted maneuver. The bearing surfaces of the aircraft may be equipped with suitable flaps in order to facilitate the transition from vertical to horizontal flight and vice versa.

Part of the power to power the RTGs during the first phase of take-off and the final phase of landing can also be derived from the internal combustion engine of the airplane similarly to the hybrid systems used in automotive and this will also allow for greater margins both on power and on the energy required for take-off and landing. The storage section (and its capacity) is the most important part of the present invention and therefore further quantitative and qualitative considerations are necessary: it includes at least one rechargeable energy storage device (RRSU) of much higher capacity both in terms of stored energy and available power than airplanes usually have (to start engines and some onboard functions). In particular helicopters, which among the vertical take-off aircraft are those that have the greatest propulsive efficiency thanks to the very high area of the rotor disc (or discs) (the ratio between the total area of propulsive flow and the maximum weight at take-off is about 0.025 m2 / kg), have a ratio between the installed power of the engine or engines that rarely falls below the value of 0.30 kW / kg. For convertiplanes that have smaller flow areas (in this case the ratio between the total flow area and the maximum take-off weight is about 0.008 m2 / kg), installed power to weight ratios of about 0.35 kW / kg. Naturally the installed power values on helicopters and tiltrotors are higher than those strictly necessary to take off and land vertically. For the present invention, as already mentioned, it will not be possible to realistically have high flow areas as for helicopters but being able to dispose of several propulsion units, also deployable, it will be possible to realistically approach the values of convertiplanes (total flow area ratios with respect to the maximum weight at take-off of about 0.008 m2 / kg) and have ratios between the power that will feed the RTG propulsion units of the present invention and the maximum take-off weight of the airplane similar to those of tiltrotors. Furthermore, this power must be supplied for a sufficient time to guarantee vertical or near vertical take-off and landing maneuvers with a certain margin. Furthermore, considering that in light airplanes there are generally values of the ratio between the installed power of the internal combustion engine (s) in kW and the maximum take-off weight which varies on average between 0.10 and 0.20 kW / kg, one can think of also exploit this power, in addition to that supplied by the accumulators, during the initial take-off or final landing phase, to power the RTGs. In order to also exploit the power of the primary motor to drive the RTG units, there should be on-board electrical generators capable of transforming a large part of the mechanical power generated by the motor into electrical power or a mechanical coupling between the endothermic engine and at least one unit. propulsive RTG. And therefore it may also be necessary to exploit the power of the primary engine during take-off that the horizontal thrust generators or traditional propellers can be disengaged or rotated at practically zero pitch during the first phase of take-off and the final phase of landing. .

The present invention can assume different configurations given by the possible combinations of the elements that compose it; however, this does not affect the dynamics of the take-off and landing phases, which remain practically unchanged whatever the configuration adopted.

Using RAPS, three take-off phases can be considered:

to. a first phase of vertical or almost vertical flight up to a certain height, which depends on the surrounding obstacles present, on the weather conditions (wind speed in particular) and on any air traffic during which the RAPS is in action which provides a resulting thrust , mainly facing upwards, controlled in module and direction. In this phase it will also be possible to exploit the power of the traditional primary engine to drive the dedicated RTG propulsion units;

b. a subsequent transition phase in which, once a certain height has been reached, while maintaining the RAPS in operation, the traditional propulsion system of the aircraft is also used to accelerate the aircraft until a sufficient translation speed is reached to have the necessary lift of the wings to support the aircraft. During this phase the total thrust provided by the RAPS can be progressively oriented from the vertical to the horizontal direction as the progressive lift of the wings will progressively reduce the need for the vertical thrust generated by the RAPS. Alternatively, it is possible to reduce the thrust module of the RAPS and maintain its orientation mainly upwards.

c. the traditional flight phase with only the traditional propulsion system.

As for the reactions and inertial effects of the RAPS system on the aircraft, they depend on the number of flywheels and impellers present, on their arrangement and on the rotating / counter-rotating couplings that will be created and which can be managed to the advantage of the maneuverability and stability of the aircraft. airplane itself.

The amount of energy to be stored can be obtained by using, before take-off, the engine of the aircraft for a certain time (for example 30 kW for 5 min, or 50 kW for 3 min) and / or by recovering part of the heat produced by combustion through MGUH type units recently developed for motor racing. The energy required to charge the accumulations before take-off can also be obtained with the use of an external charging device.

Figs. 1 and 2 give an example, indicative only for demonstration purposes of the necessary energy balance, of the ability of the RAPS soon to be introduced in Formula 1 to obtain the take-off trajectories, assumed for an aircraft weighing about 500 kg, with thrust from the primary engine of 1,000 N and minimum acceptable speed of 100 km / h and for an aircraft weighing 3000 kg, with traditional thrust of 7,500 N and minimum acceptable speed of 150 km / h.

In the examples shown in Figures 1 and 2, to highlight the good margins allowed by the invention, a power / weight ratio of about 0.50 kW / kg was assumed to be much higher than that of helicopters and tiltrotors. For the 500 kg aircraft, the analyzes therefore considered a RAPS comprising 2 storage units of 120 kW / 33 s to give a maximum additional thrust of 6,000 N and for that of 3,000 kg a RAPS comprising 4 units of 360 kW / 33 s to obtain a maximum additional propulsive thrust of 36,000 N

The take-off trajectories chosen in these examples are far more extreme and binding than those usually used by helicopters and this to highlight the advantages of the innovative idea proposed and the margins it would allow for the vertical take-off of airplanes.

Once in flight and before landing, the units can be recharged in two ways:

• By means of the engine of the aircraft itself, using part of its available power (generally the engines have higher powers than those required for cruising) and / or by recovering part of the thermal energy produced by the engine through MGUH units.

• By means of on-board generators. It can therefore be specially mounted turbines such as RATs (Ram Air Turbines), commonly installed on large aircraft and used as emergency power sources in the event of total engine loss. The RATs are usually extracted only if their use is required, generating energy thanks to the air flow that hits them due to the speed of the aircraft. It is also possible to use photovoltaic cells mounted on the plane, a solution considered useful mainly in some types of UAVs.

The power used to recharge the batteries in flight must be compatible with the flight time and will also depend on the remaining charge level of the batteries after take-off.

Similarly, with regard to landing, three phases can be considered:

to. The first traditional flight phase in which it is still necessary to descend to a height and speed compatible with the characteristics of the airplane, with any local air traffic and surrounding obstacles;

b. A subsequent phase in which the additional propulsion system is brought into take-off / landing configuration and then activated to provide, by modulating its value, an additional thrust such as to achieve the desired flight trajectory in deceleration up to stationary flight, then realizing the rate of flight. desired descent possibly also deriving energy from the primary motor. During the transition from the cruise configuration to the take-off / landing configuration, depending on the chosen solutions, there will be variations in the lift and drag of the airplane which must be adequately considered to keep the flight safe during this transition;

c. A final phase in which the primary propulsion system is deactivated and the additional thrust of the RAPS is gradually decreased, in order to make the airplane descend following the trajectory with the desired descent speed, controlling attitude and direction through the maneuvering mechanisms. Similarly to the initial take-off phase, in this phase it will also be possible to exploit the power of the primary engine to operate the RTGs.

Figs. 3 and 4 report as pure example of the ability of the RAPS soon to be introduced in Formula 1 to obtain the desired landing trajectories for a 500 kg aircraft, which is carried in normal flight up to a height of 100 m with a speed of 100 km / h and for an airplane of 3000 kg, which is similarly raised up to a height of 150 m with a speed of 150 km / h.

Also in this case, the chosen landing trajectories are much wider than those usually made by helicopters to highlight the advantages of the innovative idea proposed and the margins it would allow for the vertical landing of airplanes.

The RAPS system will also make it possible to interrupt the landing or take-off maneuver at any stage and return the aircraft to safe operating conditions.

Although it is not theoretically necessary to specify a minimum number of propulsive elements, reference will be made in the text and drawings, for descriptive purposes only and without any loss of generality, to versions with four or six RTG units suitably arranged in a to allow easy management of the aircraft during take-off and landing without affecting too much on the construction complexity.

In a first version of the invention, the airplane is equipped with:

• a number of kinetic type RRSUs equal to that of the additional thrust generators;

• one or more mechanical RTGs, also of the deployable type;

• one or more RRUs;

• an RCU;

The flywheels are positioned in the immediate vicinity of the thrust generators (RTGs) (ideally in a coaxial position). The configuration is completed by an electric motor and a CVT for each flywheel.

During the charging phase, the electricity from the RRUs is transferred to the electric motors and transformed into kinetic energy; then through the CVT it is sent to the flywheels for accumulation.

During the discharge phase, the mechanical energy taken from the flywheels through the CVTs is sent to the propellers or fans. The control of the same speed is carried out by checking the mechanical torque exchanged between the input and output of the variator.

In another version of the invention, the aircraft is equipped with:

• A number of kinetic RRSUs driven by electric motors equal to that of the additional thrust generators;

• One or more electrical RTGs, also of the deployable type;

• One or more RRUs;

• An RCU;

The configuration is completed by a number of MGU units (Motor Generator Units) equal to that of the additional thrust generators and by power management devices for controlling the electrical energy between the system components.

Also in this case the flywheels are positioned in the immediate vicinity of the thrusters (ideally and if appropriate coaxial).

During the charging phase, the electricity from the RRU is sent to the individual MGUs to be converted into kinetic energy and stored in the flywheels.

During the discharge phase, the MGU units carry out the reverse transformation on the energy taken from the flywheels and it, after treatment operated by the power management devices, is transferred to the additional electrical thrust generators RTG's.

In this version, the energy distribution is carried out through electrical connections, which allows the thrust generators to be distributed in the most suitable positions, as their connection is particularly easy.

In another version of the invention, the airplane is equipped with:

• One or more kinetic RRSUs;

• One or more electrical RTGs, also of the deployable type;

• One or more RRUs;

• An RCU;

In this case the flywheel, or the bank of flywheels, will be placed as close to the reloading units as possible.

There is also a single MGU unit which, during the charging phase, transforms the electrical energy from the RRU into mechanical energy to be stored in the flywheel (or flywheels).

During the discharge phase, the MGU takes mechanical energy from the flywheel (or flywheels) and converts it into electrical energy. The latter, after being treated by the power management devices, is then sent to the additional thrust generators.

In this version, as in the previous one, the energy distribution is carried out through electrical connections, which allows the thrust generators to be distributed in the most suitable positions, as their connection is particularly easy.

In another version of the invention, the aircraft is equipped with:

• One or more RRSU of electrochemical or electrical type;

• One or more electrical RTGs, also of the deployable type;

• One or more RRUs;

• An RCU;

Also in this case the storage units can be positioned in the immediate vicinity of the charging units.

The configuration is completed by an adequate number of power management devices to control the transfer of electrical energy between the system components.

During the charging phase, the electricity from the RRUs is suitably treated by the power management devices and then stored in the RRSU.

During the discharge phase, the electricity taken from the RRSU is adapted to the needs of the loads by means of power management devices and sent to the additional thrust generators. Since, as before, the distribution of energy is achieved through electrical connections, the additional thrust generators can be distributed on the surface of the airplane in the most suitable positions, making their connection to the rest of the system particularly easy.

In another version of the invention, the aircraft is equipped with:

• Two or more RRSU of both kinetic and electrochemical / electrical type;

• One or more electrical RTGs, also of the deployable type;

• One or more RRUs;

• An RCU;

During the charging phase, therefore, the electrical energy of the RRUs is partially or completely converted into mechanics by MGU units integrated with the flywheels in order to recharge them, and partially or completely adapted by the power management devices to be stored in the accumulators electrochemicals. The distribution of energy between the RRSUs will be decided by the user or by the control unit itself, based on predefined preferential parameters, the available capacity of the individual RRSUs, etc ...

While discharging:

• the MGU takes kinetic energy from the flywheels, transforms it into energy and, suitably conditioned by the power management units, is sent to the additional thrust generators (RTG);

• the electrochemical accumulators directly supply electricity which, possibly adapted by the power management units, is sent to the additional thrust generators.

Also in this case, the distribution of energy takes place only through electrical connections and the additional thrust generators can therefore be distributed on the surface of the airplane in the most suitable positions.

In all the versions described above, it will also be possible to use the power supplied by the engine or the traditional primary engines of the airplane during the first phase of take-off and the final landing phase. This is possible if there is a device that allows you to disconnect the traditional horizontal thrust system or allows you to bring the propeller to a minimum pitch in order to take advantage of the mechanical power generated by the internal combustion engine to drive the electric generator.

In all the versions described above, the arrangement of the various elements may be, compatibly with their dimensions and overall dimensions, the one that best suits the characteristics of the airplane. For illustrative purposes only, some of the possible solutions will be reported in the description of the patent and in the attached tables.

In all previous versions, the RTG units can be fixed or placed on deployable supports. In any case, they may be in an open and ready-to-operate landing / take-off configuration or in a closed cruise configuration.

DESCRIPTION

In a first version of the invention, the additional propulsion system provides for an energy storage of the kinetic type and can be schematized as in Fig. 5: overall there are a number of flywheels 100 equal to the number of additional thrust generators 106 with mechanical drive and the configuration is completed by suitable energy conversion and speed control devices.

During the charging phase, the charging unit (or units) 105 generate electricity through the methods currently available on the airplane and which include:

• withdrawal of electricity from the primary propulsion system of the aircraft, from generators or from photovoltaic cells;

• conversion of thermal energy generated by the aircraft's primary engine into electrical energy;

• withdrawal of mechanical energy from the primary propulsion system or from auxiliary turbines;

If there is, in addition to electricity, also (or only) mechanical energy which in this case is converted into electricity by a generator 102. The electricity is then sent to the storage units. Immediately before them, 103 electric motors are positioned whose function is to convert electrical energy into mechanics and the latter is used to recharge the flywheels (increase their rotation speed) by means of a CVT 104 continuous speed variator.

During the discharge phase, energy is taken from the flywheels 100 by means of the continuous speed variator 104 and sent directly to the respective thrust generators 106, controlling the power sent by controlling the torque delivered.

In this phase it is also possible to use the power of the airplane's primary engine (or engines) 101.

The operations indicated are carried out using the sensors and actuators of the control unit which constitutes the interface between the user and the system.

As mentioned earlier, there are many alternatives for the arrangement of the additional thrust generators and other system components. They will depend on their number, on the structure and type of aircraft as well as on the chosen system configuration. By way of example only and without loss of generality, some of them will be illustrated.

In particular, for the version of the invention just described, various installations are possible. A possible installation is shown in Fig. 6a, which shows the arrangement of the various elements that make up a RAPS system on an airplane 200. In this case the additional thrust generators 106 are mounted on special deployable arms 201, which can rotate around axes parallel to the y axis to pass from the take-off / landing configuration illustrated in Fig.6a to the cruise configuration illustrated in Fig.6b with the additional propulsion devices in a rest position which, even using suitable hatches, allows maintain good aerodynamic efficiency of the airplane.

Another possible installation can be with the additional thrust generators 106 mounted on special deployable arms 201, which can rotate around axes parallel to the z axis to switch from the take-off / landing configuration shown in Fig.7a to the cruise configuration. shown in Fig. 7b with the additional propulsion devices in a rest position which allows to maintain good aerodynamic efficiency of the airplane.

In a further installation illustrated in Fig. 8a the additional thrust generators 106 are mounted on movable arms 201, hinged to the wings 202 with the possibility of rotating along the x axis (pitch). This allows them, in a cruise configuration, to position themselves within or under the wings themselves so as not to affect the aerodynamics of the airplane, possibly through reclosable hatches (Fig. 8b). In addition, small additional tail thrust generators may also be present.

In all these cases, in the take-off / landing configuration it is possible to control the rotation of the arms 201 around the x axis (pitch) and the speed of the fans 106 (independently for each) to control the attitude of the airplane;

An installation is also possible as illustrated in Fig. 9. In this case the thrust generators 106 are integrated into the structure of the airplane 200 and are fixed (on the wings 202 and on the fuselage 203). In particular, in this configuration, the openings for the propellers / fans are equipped with special closing mechanisms for the cruise phases and which, on the other hand, in the take-off / landing configuration in the exit part have elements that can direct the air flows to control of the airplane. Fig. 10a shows a lateral section of an airfoil in correspondence with a thrust generator: the covering mechanism 204 is completely open, with the fins 204a that constitute it arranged vertically. The air flow 204b generated by the blades is therefore directed perpendicular to the wing.

By varying the angle of the fins 204a you can change the direction of the air flow as shown in Fig. 10b. When the airplane is in a cruise flight phase (or in any case when the use of additional thrust generators is not required) the flaps 204a are brought horizontally, closing the opening (Fig.10c).

The storage units 100 with their set of engines 103 and CVT 104, given their limited size, are mounted immediately above the additional thrust generators 106.

The control unit 109 is located in the cockpit, to integrate the on-board instrumentation. Through this unit it will be possible to switch from the take-off / landing configuration to the cruise configuration, check the state of charge and the charge of the accumulators 100 and control the rotation speed and flow orientation of each thrust generator 106.

A second version of the invention provides for accumulation devices of the kinetic type in a number equal to the additional thrust generators operated, in this case, electrically, and is shown in Fig. 11: compared to the previous case there is no interaction with the flywheels by means of a variator speed but through Motor / Generator Units (MGU) 107.

An MGU unit is a reversible electric machine capable of functioning both as an electric motor (and therefore transforming electrical energy into mechanical energy) and as a generator (and transforming mechanical energy into electrical energy).

During the charging phase, the charging unit (or units) 105 operate exactly as in the previous case, including the possible conversion of mechanical energy into electrical by the generator 102. The resulting electrical energy is converted into kinetic energy by the individual MGU 107 and stored in flywheels.

During the discharge phase, the MGU 107 take kinetic energy from their respective flywheels and convert it into electrical energy: before this is used to drive the additional thrust generators 106 it passes through a power management unit 108 which regulates it suitably parameters so that it is compatible with the load (adjustment of voltage levels, current levels, smoothing of waveforms, etc…).

As in the previous case, in this phase it is also possible to use the power of the airplane's primary engine (or engines) 101.

Also this version of the invention lends itself to an arrangement of the elements similar to the first, with the storage units 100 (including MGU 107 and power electronics 108) in the immediate vicinity of the additional thrust generators 106.

As previously mentioned, also for this version the additional thrust generators and the other components of the system can be placed in the most convenient positions. The configuration chosen will depend on the number of units, the structure and the type of airplane.

In another version of the invention, the system has a flywheel (or a bank of flywheels) located in the immediate vicinity (or in any case as close as possible) to the charging section, while the additional thrust generators are electrically operated as shown. in Fig. 12.

During the charging phase, the electricity from the charging section is converted into mechanical energy by the MGU 107 and stored in the flywheel or flywheels 100.

During the discharge phase, the MGU 107 takes mechanical energy from the flywheel 100, to send it to the additional thrust generators 106, to which it arrives after being suitably processed by the power electronics 108.

As in the previous cases, in this phase it is also possible to use the power of the airplane's primary 101 engine (or engines).

As with previous versions, there are several possibilities to place additional thrust generators and other system components.

In another version of the invention, the storage section is of the electrochemical / electrical type (for example batteries or ultra-capacitors) while the additional thrust generators are electrically operated. The diagram can be seen in Fig. 13: during the charging phase, the charging section 105 with possible generator 102 operates in the same way as the previous versions. The electricity coming from it is duly conditioned by dedicated power management devices 108a and then stored in the electrochemical / electrical storage device 100a.

During the discharge phase, the electrochemical / electric accumulator 100a delivers electricity to the additional thrust generators 106 which it reaches after treatment in the power management units 108 (present in a number equal to that of the propellers).

As in the previous cases, it is possible to use the power of the airplane's primary 101 engine (or engines).

As in the previous versions it will be possible to place the additional thrust generators and the other components of the system in the most convenient places and they can be both fixed and deployable as illustrated in Figs. 6, 7, 8 and 9.

A solution particularly suitable for this application but which can be used by all the versions illustrated can be constituted by particular propulsive elements shown in Fig. 14. It consists of a propeller or fan 203 with a certain number of blades 203a, located in a circular space that can be fixed with the aircraft or mounted on deployable stands. Within this space there is a stator-type winding 203b, while the tips of the blades are connected to each other by means of a metal ring 203c on which permanent magnets 203d are fixed. An external electric motor is therefore formed which can allow weight savings and which can reach high rotation speeds.

Obviously, this technological solution for the propellers / fans is also applicable in all other cases. Otherwise the electric motor can be placed in the hub of the fan possibly by means of a reducer.

In another version of the invention, the storage system consists of both kinetic accumulators and electrochemical / electrical accumulators and is shown in Fig. 15.

During the charging phase, the electricity coming from the charging section 105 is conveyed in proportions established by the user or, automatically, by the control unit (based on parameters such as residual charge of the individual accumulators, etc ...) towards the flywheel (or flywheels) 100 and towards the electrochemical / electrical accumulators 100a. As for the kinetic accumulation, the MGU 107 unit takes care of converting the electrical energy in order to be able to store it in the flywheel (or flywheels) 100. As regards the electrochemical / electrical accumulation, the electrical energy may require to be suitably conditioned by a power management unit 108a before being collected in the batteries or capacitors.

During the discharge phase, energy is requested from one or both of the storage sections on the decision of the user or the control unit based on the same parameters that regulate the flow. The one coming from the flywheels 100 needs to be converted into electricity by the MGU 107 unit. The resulting one is directed towards the additional thrust generators 106 which it arrives after appropriate treatment in the power management units 108.

As in the previous versions it will be possible to place the additional thrust generators and the other components of the system in the most convenient places and they can be both fixed and deployable as illustrated in Figs. 6, 7, 8 and 9.

As in the previous cases, it is also possible to use the power of the airplane's primary engine (or engines) 101 in the phases in which high horizontal traction is not required.

Fig. 16a shows a take-off phase using the system object of the present invention.

The 200 airplane is positioned at the take-off point. The additional propulsion system is set up in the take-off / landing configuration and, by feeding it, a thrust 111a greater than the weight of the airplane itself is generated (A), obtaining its elevation along the perpendicular to the ground up to a height h1 (B) , compatible with the maneuver of transition to the cruise flight and also dependent on any obstacles or air traffic present in the area.

Once this altitude is reached, the primary propulsion system is activated which gives rise to a horizontal force 111c whose purpose is to increase the translational speed of the aircraft and therefore the lift of the wings (C). Throughout this phase, the thrust of the additional propulsion system always remains oriented upwards even if it can be reduced in modulus. When the speed along the Y axis is such as to allow the achievement of the self-supporting condition, the normal cruise phase begins with the primary propulsion system only (D), while the additional one is deactivated and returned to the closed cruise configuration.

Also shown in Fig.16a is the other possibility offered by the present invention: once the height h1 has been reached and the primary propulsion system is activated, as the horizontal speed and therefore the lift of the wings increase, the thrust of the additional system can be gradually oriented forward and positioned as in 111b (ie forming an angle α with the vertical). In this way it gives rise to two components: a vertical one that roughly equals the difference between the weight of the airplane and the lift of the wings at that moment and a horizontal one that adds to that of the primary propulsion system and therefore increases the speed of horizontal translation, allowing the achievement of self-sufficiency in a shorter time.

In Fig. 16b another take-off maneuver is shown in which it is highlighted how by varying the various propulsive flows, the attitude of the airplane can be varied. In this case there could be propulsive flows that do not require mechanisms to orient them with respect to the airplane (orienting the generators themselves if they are deployable or diverting the flow in the case of fixed thrust generators) as the orientation of the flows with respect to the vertical can be obtained by varying the attitude of the airplane itself.

Fig. 17a shows a landing phase using the system object of the present invention.

While the airplane 100 is in flight moved by the force 111c of the primary propulsion system only (A), the additional propulsion system is set up in the take-off / landing configuration. The airplane begins the descent towards a h2 altitude compatible with the transition maneuver from the cruise flight, with any local air traffic and the surrounding obstacles, simultaneously slowing down the speed (B) until a safe condition of slow flight; the additional propulsion system is then activated which generates thrust 111a.

The intensity of this thrust 111a will be modulated to allow a descent at the desired speed. Once on the ground, the additional propulsion system is deactivated and returned to the cruise configuration (rest position).

Also in Fig. 17a another possibility of the present invention is shown: in the first phase of the landing maneuver, the additional propulsion system can be activated and oriented in a way (111b) to contribute to the slowdown of the airplane (B). As the horizontal speed decreases, the thrust 111b is gradually oriented upwards, forming an angle α with the vertical (C), to help support the vehicle, and then proceed to descend at a controlled speed. During this last phase of descent, the flows produced by the additional propulsion system will not necessarily be vertical but can be oriented as needed to maintain the correct attitude of the aircraft (D).

In Fig. 17b a landing maneuver is again represented in which it is shown how by modifying the various thrusts it is possible to change the attitude of the aircraft. As previously indicated for Fig.16b, also in this case it is possible to have propulsion flows that do not require mechanisms to orient them with respect to the aircraft (orienting the generators themselves if they are deployable or divert the flow in the case of fixed thrust generators) but the orientation of the propulsive flows from the vertical can be obtained by varying the attitude

same as the plane.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows the take-off trajectory of an aircraft weighing 500 kg, equipped with a primary propeller of 1000N and with an additional propulsion system consisting of 2 storage units of 120kW / 33s, until reaching a horizontal speed of 100 km / h.

Fig. 2 shows the take-off trajectory of an airplane weighing 3000 kg, equipped with a primary thruster of 7500N and with an additional propulsion system consisting of 4 storage units of 360kW / 33s, until reaching a speed of 150 km / h.

Fig. 3 shows the landing trajectory of an aircraft traveling at a speed of 100 km / h, weighing 500 kg, equipped with a primary propeller of 1000N and with an additional propulsion system consisting of 2 storage units of 120kW. / 33s.

Fig. 4 shows the landing trajectory of an airplane traveling at a speed of 150 km / h, weighing 3000 kg, equipped with a primary propeller of 7000N and with an additional propulsion system consisting of 4 storage units of 360kW. / 33s.

Fig. 5 shows a version of the invention with kinetic type storage units equal to the number of additional mechanically operated thrust generators.

Figs. 6a and 6b show a possible installation of the invention using foldable and adjustable arms respectively in the take-off / landing and in the cruise configuration.

Figs. 7a and 7b show a possible installation of the invention for canard aircraft respectively in the take-off / landing and in the cruise configuration.

Figs 8a and 8b show another possible installation of the invention.

Fig. 9 shows a possible installation of the invention with the additional fixed thrust generators integrated into the aircraft structure.

Figs. 10a, 10b, 10c show a possible lower mechanism for covering the additional thrust generators in the open, partially open position to divert the air flow, closed.

Fig. 11 shows a version of the invention with kinetic type storage units equal to the number of additional electrically operated thrust generators.

Fig. 12 shows a version of the invention with centralized kinetic type storage units and additional electrically operated thrust generators.

Fig. 13 shows a version of the invention with centralized electrochemical / electrical storage units and with additional electrically operated thrust generators.

Fig. 14 shows a particular type of thrust generator which can be used in the present invention.

Fig. 15 shows a version of the invention with both kinetic and electrochemical / electrical centralized storage units and with additional electrically operated thrust generators.

Fig.16a shows take-off maneuver using the claimed system.

Fig. 16b shows the execution of the take-off maneuver also controlling the attitude of the aircraft to direct the propulsive flows.

Fig. 17a shows the execution of the landing maneuver using the claimed system.

Fig. 17b shows the execution of the landing maneuver also controlling the attitude of the airplane to direct the propulsive flows.

Claims (1)

CLAIMS 1. An additional propulsion system for the generation of a predominantly vertical thrust for airplanes, piloted or unmanned, equipped with internal combustion engines or primary engines, which allows VTOL / STOL take-offs and landings and which is based on an energy storage system , also used in combination with the primary motor or motors to power additional suitably positioned thrust generators, comprising: to. at least one rechargeable device for energy storage; b. one or more thrust generators, distinct from the primary ones of the airplane and consisting of propellers and / or fans also ducted and counter-rotating, powered by mechanical or electrical energy, fixed and / or mounted on deployable elements, capable of being opened in the configuration of take-off / landing to produce an acceleration of the air flow and obtain a total thrust greater than the weight of the airplane, also by orienting the flows, and to be able to be closed in the cruise configuration with closing of the openings and / or the folding of the opening elements so as to maintain good aerodynamic characteristics of the aircraft for wing lift flight; c. a control unit for the management in total autonomy, in partial autonomy or on total control of the pilot, equipped with sensors and actuators to perform take-off and landing maneuvers; d. at least one charging section in which mechanical and / or thermal and / or electrical power is derived from the primary endothermic engine of the airplane and / or from auxiliary generators supplied to the airplane or external to recharge the energy storage device; 2. A system defined according to claim 1) wherein: to. the energy storage device (s) consists of flywheels; b. the additional thrust generators are powered by mechanical energy; c. the thrust generators are fixed; 3. A system defined according to claim 1) wherein: to. the energy storage device (s) consists of flywheels; b. the thrust generators are powered by electricity; c. the thrust generators are fixed; 4. A system defined according to claim 1) wherein: to. the energy storage device (s) consists of electrochemical or ultra-capacitor batteries; b. the additional thrust generators are powered by electricity; c. the thrust generators are fixed; 5. A system defined according to claim 1) wherein: to. the storage device (s) are a combination of flywheels, batteries and ultracapacitors; b. the additional thrust generators are powered by electrical energy or mechanical energy; c. the thrust generators are fixed; 6. A system defined according to claims 2), 3), 4) or 5) in which thrust generators instead of fixed ones are deployable; 7. A method for performing vertical take-off of piloted or unmanned airplanes equipped with a primary propulsion system, piloted or unmanned, having one or more rechargeable energy storage devices, one or more additional thrust generators, one or more charging mechanisms, a control unit, comprising: to. ground recharging of energy storage devices, using the recharging devices supplied, deriving energy from the primary internal combustion engine or from external generators; b. preparation of the aircraft take-off / landing configuration with the additional thrust generators open; c. activation of the additional thrust generators, using the energy available in the storage devices, possibly also deriving power from the primary internal combustion engine, to generate a vertical thrust greater than the weight of the airplane until reaching a height compatible with the transition maneuver to cruise flight, with any local air traffic and surrounding obstacles, appropriately controlling the various propulsive flows to maintain the desired attitude and trajectory; d. activation of the primary propulsion system in order to reach the translational speed necessary to generate sufficient lift of the wings; And. Deactivation of the additional propulsion system, closing of the additional thrust generators to switch to the cruise configuration; f. continuation of the flight using the primary propulsion system; g. recharging the storage devices, using the recharging devices and deriving energy from the primary engine of the airplane and / or from on-board auxiliary generators including any thermal energy recovery units or photovoltaic cells; 8. A method of vertical landing of airplanes equipped with a primary propulsion system, piloted or unmanned, having one or more rechargeable energy storage devices, one or more additional thrust generators, one or more recharging mechanisms , a control unit, comprising: to. verification, through the control unit, of the state of charge of the storage systems; b. if necessary, recharge the storage devices, using the recharging devices and deriving energy from the primary engine of the airplane and / or from on-board auxiliary generators including any thermal energy recovery units or photovoltaic cells; c. beginning of the descent towards an altitude compatible with the transition maneuver from the cruise flight, with any local air traffic and surrounding obstacles, simultaneously slowing the speed of the airplane up to a safe condition of slow flight; d. preparation of the take-off / landing configuration with the additional thrust generators open and activation of the additional propulsion system to provide additional thrust, modulating the value and direction of the propulsive flows, such as to achieve the desired flight path with deceleration up to flight stationary, with the desired rate of descent, deactivate the main engine possibly also deriving power from the primary engine; And. gradual decrease in the vertical thrust of the additional thrusters, in order to make the airplane descend following the desired trajectory and descent speed, controlling attitude and trajectory through the maneuvering mechanisms; f. after landing, deactivation of the additional propulsion system. Method according to claim 7) in which during take-off the direction of the thrust of the additional thrusters is not kept constant but, upon activation of the primary propulsion system, is gradually oriented or deflected in a horizontal direction so as to help increase the thrust. translational speed of the airplane, simultaneously reducing the vertical component as the overall lift of the wings increases; 10. Method according to claim 8) in which, during the landing phase, the thrust of the additional thrusters is initially directed forward to contribute to the slowing of the airplane, and is then gradually oriented downwards, until it becomes vertical when the vertical descent must begin;