Convertible aircraft with tandem rotors that are stopped during flight on transition to airplane mode and restarted on conversion back to helicopter flight mode

Abstract

The present application pertains to a VTOL aircraft with tandem rotors, each rotor comprising at least one hub connected to a rotational power source and brake units that control the rotation of the hubs, stopping them in predefined positions during flight, wherein each hub comprises a pair of opposing hinges incorporated into grips that have longitudinal cavities in which rotor blades are accommodated, sandwiched between bearings. Actuators move the blades through the grips until they are centred and locked or locked by the roots. Collective pitch mechanisms tilt the grips around the hinges, and the blade edges are interchangeable during flight. In helicopter mode, yaw is controlled by tail fans, and propulsion means generate a force in a direction parallel to the axis of symmetry of the aircraft.

Description

Convertible aircraft with tandem rotors that are stopped during transition to airplane mode and restarted when converting back to helicopter mode. Field of invention

[0001] The invention relates generally to VTOL (vertical takeoff and landing) aircraft and more particularly to a convertible aircraft whose tandem rotary wings act as lift rotors in helicopter mode, are stopped during the transition from flight to airplane mode, hereinafter referred to as "transition flight," and restarted during the conversion back to helicopter mode, hereinafter referred to as "conversion flight." It is also an object of the invention to provide a thrust vector control nozzle for turbine engines. State of the art

[0002] Aerodynamic limitations inherent in the main rotor prevent conventionally designed helicopters from flying as fast as fixed-wing aircraft. In a hover, the halves of the rotor disc, where the blades rotate along the sides of the fuselage, have equal speeds and therefore generate the same lift. But as airspeed increases with the aircraft's forward speed in straight-line flight, flight balance is progressively affected by an aerodynamic phenomenon known as lift dissymmetry or asymmetric lift. The half of the rotor disc, where the blades rotate in the direction of flight, upwind of the relative wind, produces more lift than the other half, where they rotate in the opposite direction, downstream.

[0003] Even counteracted by means such as automatic cyclic feathering and intermittent blade flapping, lift dissymmetry can only be effectively controlled up to a certain speed above which helicopters Single-rotor helicopters are incapable of flight. So much so that conventionally designed helicopters typically reach speeds of 150 knots or less, while turboprops can fly above 300 knots, and turbofans can fly above 450 knots. Furthermore, while helicopters typically operate at a ceiling below 20,000 feet, business jets cruise at an altitude of 36,000 to 45,000 feet with considerably greater fuel capacity and range than a helicopter with an equivalent payload.

[0004] However, it is a known fact that the performance of helicopters in vertical flight has never been equaled by any other aerial vehicle in terms of takeoff and landing range, hovering capability, maneuverability, nor lift or fuel efficiency, which explains their frequent use in a variety of civil and military applications that include corporate services, oil and gas, air ambulance with emergency medical services, defense operations, submarine / maritime surveillance and border security, in addition to a wide range of missions including search, rescue and recovery operations with direct intervention requirements in hard-to-reach areas.

[0005] Since 1934, when United States Patent US 1,951.817 was awarded to Earle Blount's "helicopter aircraft", over fifty VTOL and STOVL (short take-off and vertical landing) types were tested or proposed, but only three survived to see production production: i) the discontinued British military aircraft informally referred to as the Harrier Jump Jet; ii) the United States Lockheed Martin F-35B Lightning II STOVL fighter, whose vertical lift is provided by a single turbine engine that, in addition to generating thrust through a vector control nozzle at the tail end, powers a 50-inch diameter vertical lift fan mounted just behind the cockpit and a pair of vertical wingtip roll control blowers supplied by ducts vented by an engine fan; and iii) Earle Blount's tilt-rotor powered aircraft, which after extensive redesign, improvement, and testing became. The first tilt-rotor aircraft to be manufactured on a production scale, it is now known as the Bell Boeing V-22 Osprey and is currently in service with the United States Air Force, Navy, and Japan Self-Defense Forces.

[0006] Each rotor, sometimes called a proprotor, on a twin tilt-rotor aircraft is driven by a turboshaft engine housed in a wingtip nacelle, which can be configured to tilt with the rotor (V-22 Osprey and Leonardo AW609) or not. For example, on the U.S. military Bell V-280 Valor aircraft still in testing, the rotor tilts on its own while the engine remains parallel to the fuselage under all flight conditions. Aircraft supplied with twin tilt rotors, such as the military V-22 Osprey and the civil AW609 pending certification, are a subset of the convertible aircraft category, and although aircraft of this specification are also convertible aircraft, they do not belong to the tilt-rotor aircraft segment.

[0007] In the well-known Wikipedia graph titled "Suspended vertical lift efficiency as a function of disk loading" where five VTOL concepts are compared, the conventionally designed helicopter is shown as the most efficient vertical takeoff and landing aircraft, while the convertiplane with tilt-rotors on the tips of one wing appears in an intermediate position, and a direct-lift fighter similar to the aforementioned Lockheed Martin F-35B Lightning II, which is capable of taking off in short distances and landing vertically like a helicopter, is seen in the lower range of the same y-axis as the least efficient of the five aircraft.

[0008] Since the disc loading of a VTOL aircraft is determined by the weight of the aircraft divided by the total vertical thrust area of ​​the rotor, rotors, or thrust vector control nozzles, the larger the vertical thrust area, also referred to as disc area, the greater the lift efficiency—defined as the mass of the aircraft divided by the horsepower of its powertrain. Greater Lift efficiency means that less power is required for the aircraft's hovering vertical lift, leading to lower power requirements, smaller and less robust engines, lighter drivetrains, and correspondingly lower carbon and noise footprints.

[0009] While the impact of airflow deflected downward by the aerodynamic action of rotor blades or downwash over large wing areas remains a challenge for tilt-rotor twin-rotor aircraft, such as the aforementioned military and civil Bell Boeing V-22 Osprey and AW609 aircraft from the Italian manufacturer Leonardo, on the other hand, the ideal VTOL aeromechanical configuration must not only avoid the incidence of downwash from rotor blades over large horizontal surfaces of the aircraft itself, but also provide the lowest possible disk load, preferably even lower than that of a conventionally designed helicopter.

[0010] Considering three aeromechanical architectures with roughly equivalent capabilities—a conventionally designed aircraft, a single-rotor helicopter, and a convertible twin-rotor tilt-rotor aircraft—in terms of machine cost, the tilt-rotor aircraft costs twice the price of a helicopter and four times the cost of an airplane. Its range will be greater than that of a helicopter but considerably shorter than that of an airplane, and its typically twisted rotor blades for propulsion—in addition to being inadequately large for higher horizontal speeds and relatively small for vertical lift—require nearly twice the power of a helicopter.

[0011] Besides being the most mechanically complex and the most expensive of the three aircraft, the tilt-rotor twin-rotor aircraft places specific constraints on the position of a wing-mounted interconnecting shaft along the wingspan that is configured to power both rotors by either engine should the other engine fail. In such an arrangement of nacelles and tilting engines together, it is crucial that the power take-offs of the nacelles that connect the ends of the interconnection shaft are coaxial with the inclination axes of the nacelles which, due to such architectural restriction, are typically positioned at the rear of the wing's aerodynamic profile, whose aerodynamic center is far in front of the aircraft's center of gravity in airplane mode, making it inevitable to use a forward-swept fixed wing system, which is well known for the negative effects it can cause in structural, aerodynamic and aeroelastic terms.

[0012] It is well known that forward sweep and the mounting of heavy turboshaft engines at the wingtips increase the wing's structural mass, necessitating a correspondingly more rigid fixed-wing system, as well as the provision of a complex structure by which such a heavier and more rigid wing is incorporated into the fuselage. Furthermore, in tilt-rotor twin-engine aircraft, the interconnecting shaft is more complex and expensive than a conventional shaft because it is segmented into segments joined by couplings that allow it to misalign to accommodate the aeroelastic deformations experienced by the wing during flight.

[0013] Another factor that increases mass in forward-swept wing systems on twin-rotor tilt aircraft concerns the aforementioned forward-shifted aerodynamic center. High angles of incidence during flight tend to destabilize the aircraft, on the one hand, and, on the other, exacerbate the so-called "shake stall," a self-excited oscillation that cannot be overcome except by substantially increasing the rigidity of the fixed-wing system, which obviously would not be achieved without the increased mass.

[0014] A thrust reverser for turbine engines is an integral part of this patent application because the thrust vector control nozzle in the turbofan embodiments of the invention can be configured for exhaust bypass capabilities at angular ranges from zero to 180 degrees from the horizontal—not just the 90 degrees sufficient for vertical flight. Therefore, in some In some applications, if desired, in order to be provided with redundant landing capability, the convertible aircraft with tandem rotors proposed by the invention may be capable not only of vertical landing, but also of landing on a runway like an airplane. Given that the thrust reverser is configured to divert the exhaust thrust of a turbofan engine for both helicopter flight and airplane landing, alternatively, an aircraft according to at least one embodiment of the invention may be provided with a thrust reverser in place of a nozzle for up to 90 degrees of vectoring of the thrust generated by the engine.

[0015] As will be appreciated in detail, the thrust reverser of the invention has advantages over prior art models, notably regarding the direction of the deflected thrust. In practice, current thrust reversers are not capable of reversing 100% of the engine exhaust during aircraft deceleration on the ground, because the air jet exiting each exhaust nozzle is typically deflected into two streams that, instead of following parallel paths opposite the aircraft's motion on the runway as would be desirable, are directed obliquely up and down or sideways, so that the horizontal component of the aerodynamic deceleration force represents only a fraction of the thrust generated by the engine. The operation of the thrust vector control nozzle for turbine engines is discussed in the detailed description in conjunction with the accompanying drawings. Brief description of the invention

[0016] In a preferred embodiment, a convertible aircraft is disclosed with tandem rotors that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, the convertible aircraft being provided with a fuselage comprising a mid-section to which a fixed wing system is symmetrically attached; a forward section having a nose and a rear section having a tail assembly provided with an empennage, which comprises aerodynamic stabilizers provided with movable directional control surfaces, the front section and the rear section being provided with respective front and rear vertical lift units comprising front and rear rotor supports configured to operationally support the front and rear rotors, which rotate synchronously in opposite directions, each rotor being provided with a rotor hub comprising a rotor mast substantially vertical with respect to the attitude corresponding to level flight, the rotor mast being provided with a rotor brake unit, which controls the rotation speed of the rotor hub until stopping it at a predefined position in transition flight to airplane mode;a pair of handles integrated with cylindrical hinges provided on opposite symmetrical sides of the rotor hub, the handles being elongated to hold rotor blades, the cross-section of which is compatible with longitudinal cavities formed in the respective handles where the rotor blades fit sandwiched between bearings; an actuator configured to longitudinally move the rotor blades sandwiched between bearings until they are centered and locked in the respective handles in transition flight to airplane mode or until their roots are housed and locked in the same handles in conversion flight to helicopter mode; a collective pitch control mechanism in which an actuator tilts the handles by rotating them about the cylindrical hinges;an edge conversion system configured to alternately interchange leading edges with trailing edges of convertible rotor blades in transition flight to airplane mode or conversion flight to helicopter mode; at least one fan, electric or driven in rotation by mechanical energy, symmetrically embedded in the tail section to provide yaw control in helicopter mode and good aerodynamic properties in airplane mode after deactivation in transition flight; a rotational power source comprising at least one internal combustion engine, at least one electric motor, or at least one of each, with output shafts engaged with transmission and coupling mechanisms that power the front and rear rotors or disengage from them; and at least one propulsion means configured to produce; a propulsive force acting on the fuselage in a direction parallel to the axis of symmetry.

[0017] According to such preferred embodiment, the fuselage comprises a longitudinal roof portion projecting upwards with respect to the attitude corresponding to level flight, which is referred to as the angled longitudinal apex, extends on the axis of symmetry along the fuselage and is intended to improve the flow of the air flow diverted by the rotor blades that impacts on the fuselage in helicopter mode.

[0018] A fixed wing is a high wing, which can be a gull wing.

[0019] Aerodynamic stabilizers comprise a symmetrically centered horizontal stabilizer, the lateral ends of which are extended in the form of two inclined stabilizers such as two laterally downwardly inclined flat surfaces provided with inclined rudders.

[0020] The rear rotor support is symmetrically embedded in the rear section, while the front rotor support comprises supporting elements such as vertical pillars and horizontal beams with respect to the attitude corresponding to level flight, the pillars being symmetrically integrated into the front section and braced by a first beam, which is braced with a roof portion over a flight deck by a second beam.

[0021] The rotation planes of the front and rear rotors are separated by at least the length of a wing root chord.

[0022] The front and rear rotor masts alternately tilt to the sides of the fuselage assisted by elastic elements.

[0023] Alternatively, the front and rear rotor masts are fixed relative to the front and rear rotor mounts that support them.

[0024] The actuator that moves the rotor blades longitudinally through the grips comprises sets of electromagnets arranged both in the grips and in the rotor blades.

[0025] Alternatively, the actuator that moves the rotor blades longitudinally via the grips is electromechanical.

[0026] The collective pitch control mechanism comprises a concentric three-rod yoke, two counter-positioned toothed side rods meshing with corresponding toothed rings of the cylindrical hinges and a telescopic central rod actuated by said actuator.

[0027] The blade edge conversion system comprises a controller, a magnetic actuator and the convertible rotor blade, which comprises a spar box-type support member, the cross-section of which is that of a longitudinally symmetrical hollow chassis, such as a flattened rhombus or a geometric figure with two inclined upper and two lower flat longitudinal faces, the spar box being the length of the convertible rotor blade; a longitudinally inner section, having the same constitution and cross-section as a rotor blade of a conventionally designed helicopter and being as long as a handle;two twin convertible longitudinally outer sections, each section measuring half the difference in length of an inner longitudinally section to the length of a whole blade, the four inclined plane faces of the stringer box of the outer longitudinally sections being magnetized and each outer longitudinally section comprising a first upper skin or covering of flexible magnetized sheet detached from the stringer box and spliced ​​at the sides with a second lower skin or covering as long as both the upper skin and the outer longitudinally section, the upper skin being wider than the total width of the upper inclined faces; and said lower skin of rigid magnetized sheet being wider than the total width; of the lower inclined faces of the stringer box, the lower skin being cantilevered by a longitudinal hinge over the axis of symmetry at the boundary of the lower inclined faces.

[0028] Alternatively, the blade edge conversion system comprises a controller, an electromechanical actuator and the convertible rotor blade, which comprises a spar box-type support member, the cross-section of which is that of a longitudinally symmetrical hollow chassis, such as a quadrilateral in which the upper side is curved and the lower side is straight or nearly straight, the spar box being the length of the convertible rotor blade; a longitudinally inner section having the same constitution and cross-section as a rotor blade of a conventionally designed helicopter and being as long as a handle;two twin convertible longitudinally outer sections, each outer section measuring half the difference in length of an inner longitudinally section to the length of a whole blade and comprising a pair of lateral support elements of cross-section in the general shape of a right triangle and as long as an outer longitudinally section, the lateral support elements being attached to or integral with the sides of the stringer box of each outer longitudinally section; an upper skin and a lower skin, both adhered to the stringer box and as long as an outer longitudinally section, the lower skin being wider than the upper skin to cover the lateral support elements;a pair of twin upper skin appendages or plates of the same thickness and length as the upper skin, the twin appendages hanging attached by elastic hinges to the upper apexes of each symmetrical side of the spar box of each longitudinally outer section and serving to maintain the flow over the trailing edge in a laminar regime; and a pair of twin rotating appendages as long as a longitudinally outer section, the elongated cross-section of which illustrates the leading edge as rounded and the trailing edge as tapered, the twin rotating appendages being; attached to opposite symmetrical sides of the lateral support members and configured to be rotated by the actuator about their own axes of the rounded edges or leading edges.

[0029] Alternatively, the rotor blades of both the front and rear rotors are provided with fixed or immovable leading and trailing edges.

[0030] The engine is a turbine engine.

[0031] Alternatively, the rotational power source that drives the front and rear rotors and the means of propulsion are electric.

[0032] In a second preferred embodiment, a convertible aircraft is disclosed being provided with a fuselage comprising a mid-section to which a fixed wing system is symmetrically coupled;a forward section having a nose and a rear section having a tail assembly provided with an empennage, which comprises aerodynamic stabilizers provided with movable directional control surfaces, the forward section and the rear section being provided with respective forward and rear vertical lift units comprising forward and rear rotor struts configured to operationally support the forward and rear coaxial rotors, each coaxial rotor being provided with two counter-rotating rotor hubs comprising concentric rotor masts substantially vertical with respect to the attitude corresponding to level flight, an inner mast and an outer mast being provided with rotor brake units, which control the rotation speed of the rotor hubs until stopping them in a predefined position in transition flight to airplane mode;a pair of handles integral with cylindrical hinges provided on opposite symmetrical sides of each rotor hub, the handles being elongated to hold rotor blades, the cross-section of which is compatible with longitudinal cavities formed in the respective handles where the rotor blades fit sandwiched between bearings; actuators configured to move; longitudinally the rotor blades sandwiched between bearings until they are centered and locked in their respective grips in transition flight to airplane mode or until their roots are housed and locked in the same grips in conversion flight to helicopter mode; collective pitch control mechanisms in which actuators tilt the grips by rotating them about cylindrical hinges; an edge conversion system configured to alternately interchange leading edges with trailing edges of the convertible rotor blades in transition flight to airplane mode or conversion flight to helicopter mode; at least one fan, electric or driven in rotation by mechanical energy, symmetrically embedded in the tail section to provide yaw control in helicopter mode and good aerodynamic properties in airplane mode after deactivation in transition flight;at least one rotational power source comprising at least one internal combustion engine, at least one electric motor, or at least one of each, with output shafts engaged with transmission and coupling mechanisms that power the front and rear coaxial rotors or disengage from them; and at least one propulsion means configured to produce a propulsive force acting on the fuselage in a direction parallel to the axis of symmetry.;

[0033] According to such a preferred embodiment, the front rotor strut comprises a single-piece column symmetrically integrated from the nose to a first roof portion of the fuselage.

[0034] Each front and rear coaxial rotor comprises two rotor blades configured to be stopped, centered, and locked at their respective grips in airplane mode transition flight, while the other two rotor blades are parked over the fuselage.

[0035] The collective pitch control mechanisms comprise an upper rotor hub integrated with the inner mast and a lower rotor hub integrated with the outer mast, the inner mast being provided with a first yoke concentric comprising a telescopic central rod connected with a first actuator and two counter-positioned toothed side rods meshing with corresponding toothed rings of the cylindrical hinges; the outer mast being provided with a second concentric yoke comprising two twin rings joined by rolling bodies, a lower (stationary) ring being provided with telescopic side rods connected with a second actuator and an upper (rotary) ring provided with two counter-positioned toothed side rods meshing with corresponding toothed rings of the cylindrical hinges.

[0036] Alternatively, the internal combustion engine is a turbofan engine.

[0037] A drive shaft of a front fan or turbofan engine fan feeds an output shaft meshed with a drive shaft, both housed upstream of the front fan in a stationary fairing, which comprises a longitudinally elongated conical portion forward of the front fan, being configured to support the output shaft, and an aerodynamically tapered portion extending in a direction perpendicular to the conical portion, being configured to support the drive shaft.

[0038] Alternatively, the output shaft and drive shaft are positioned downstream of the front fan of the turbofan engine.

[0039] The turbofan engine is provided with a nacelle, an exhaust nozzle and a thrust vector control system comprising an articulated duct referred to as a vectoring nozzle, which is configured from the interconnection of a plurality of nozzle segments obtained from the radial sectioning of a toroidal tube and joined together by symmetrically centered hinges, a first nozzle segment being integrated with a pair of twin side plates, in the form of one or two quadrants integrated with twin side pulleys of a central shaft or two lateral ones, which are symmetrically integrated with a lower outer edge of the exhaust nozzle just below the engine exhaust, and a last nozzle segment connected with an actuator by a rod intended to manipulate the nozzle. vectoring at any angle of curvature, from fully unrolled and extended within a fairing symmetrically arranged over the nacelle, to fully rolled around its own axis, outside the fairing and within a vertical plane with respect to the attitude corresponding to level flight downstream of the exhaust nozzle.

[0040] The actuator is provided with a telescopic rod or, alternatively, the actuator is provided with a rod of a device comprising a ball nut screw shaft. Brief description of the drawings

[0041] For a better understanding of the invention and to show more clearly how it can be carried out, reference will now be made to the attached drawings, not necessarily to scale, in which similar parts and components are typically identified with similar reference characters in the different examples of embodiment revealed throughout the various views, of which:

[0042] FIGS. 1-3 are two complete views and one partial view of a small convertible turboprop hybrid-electric aircraft with tandem rotors;

[0043] FIG. 4 is a perspective view of a front rotor mount;

[0044] FIGS. 5-7 are perspective views of a front rotor hub provided with a rotor blade collective pitch control system;

[0045] FIG. 8 is a perspective view of the preceding aircraft provided with an intermittent rotor mast tilt system by the aerodynamic action of alternately flapping front and rear rotor blades in rotary wing flight;

[0046] FIG. 9 is a front view of an exemplary embodiment of the rotor mast intermittent tilt system of FIG. 8;

[0047] FIG. 10 is a perspective view of the exemplary embodiment of the rotor mast intermittent tilt system of FIG. 9;

[0048] FIG. 11 is a perspective view of a second embodiment of the intermittent rotor mast tilt system;

[0049] FIGS. 12-13 are a perspective and side elevation of an exemplary embodiment of a rotor blade handle;

[0050] FIGS. 14-15 are cross-sections of two exemplary embodiments of rotor blades configured to convert leading edges to trailing edges, and vice versa, during flight;

[0051] FIGS. 16-18 are perspective views of the exemplary embodiment of the rotor blade illustrated in cross-section in FIG. 15;

[0052] FIGS. 19-23 are three full and two partial views of an unmanned convertible aircraft with tandem coaxial rotors and two twin tail turbofan engines provided with thrust vector control nozzles;

[0053] FIGS. 24-25 are perspective views of a rotational power transmission system from a turbofan engine output shaft;

[0054] FIGS. 26-28 are perspective views of a thrust vector control nozzle for turbine engines; and

[0055] FIGS. 29-30 are a partial and a complete view of a thrust reverser for turbine engines; Detailed description of examples of embodiment of the invention

[0056] The objects of the invention and the means and methods for carrying them out will be described below in such detail as to be recognizable to one skilled in the art. Before being discussed in detail, however, it should be It is understood that the invention is not limited to the specific constituent parts of the devices described, as such devices may vary. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. Furthermore, it is fully recognized that the different components of the aeromechanical configurations discussed may be employed separately or in any suitable combination to produce the desired results. Therefore, the disclosed embodiments are not individual arrangements that would not be interrelated, but may also be taken in conjunction with other arrangements.Thus, if a specific characteristic is not covered by a first modality, but is covered by a second, the person skilled in the art will understand that this does not necessarily mean that such characteristic cannot appear in said first modality, as he would understand that the essence of this application is to report the mentioned characteristic for any modality and that this was done not only for the sake of clarity, but also to keep the descriptive report in a manageable volume.

[0057] As to the spatial orientation of the devices described in this patent document, the terms vertical and horizontal refer to directions relative to the convertible aircraft of the invention when in level flight.

[0058] According to the invention, a structural, functional, aerodynamic, and operational approach is disclosed for a convertible tandem aircraft, also referred to as a VTOL aircraft, capable of flying either like a helicopter, in which case the rotors rotate about substantially vertical axes to lift and support the aircraft in flight, or like an airplane, in which case the rotors are intermittently arranged to provide good aerodynamic properties. The convertible aircraft comprises a fuselage with forward, mid, and rear sections. A fixed wing system and an empennage extend laterally on either side of the fuselage, and power units (herein understood as rotational power sources) may be housed in the forward and rear sections or only in the rear section, comprise at least one internal combustion engine, such as a turbine engine, at least one electric motor, or at least one of each. A vertical lift unit (herein understood as the set of means for generating vertical thrust) comprises said rotors in tandem mechanically coupled to the power units along drive paths comprising gearboxes and an eventual interconnecting shaft, each rotor being provided with at least one rotor hub comprising a number of rotor blades. A propulsion unit (herein understood as the set of means for generating thrust parallel to the axis of symmetry of the aircraft) comprises at least one propeller provided with a number of propeller blades or, if at least one turbofan engine is present, at least one thrust vector control nozzle.

[0059] In a first configuration, front and rear single-hub rotors rotate synchronously in opposite directions over the front and rear fuselage sections. In another embodiment, instead of just one hub per rotor, each front and rear rotor comprises a pair of coaxial hubs. Coaxial or non-coaxial, the rotors of the invention are positioned on the aircraft's axis of symmetry in such a way relative to the fixed wing that, during VTOL, transition, and conversion flight, the downwash induced by the aerodynamic action of their rotating blades does not collide head-on with substantially horizontal surfaces of the aircraft. In addition to operating all flight modes free of aerodynamic overloads from rotor blades, the convertible aircraft of the invention is characterized by a remarkably low disk load—equivalent to or even lower than the average of around 45 kg / m. 2 of a conventionally designed helicopter with two or three engines.

[0060] On the other hand, its cruising speed should be the same as that of a prior art turboprop or turbofan aircraft because, due to its characteristics and architecture, the aircraft proposed by the invention can be provided with turboprop, turbofan, electric, or hybrid-electric propulsion like an airplane. Therefore, Unlike helicopters and twin tilt-rotor aircraft, which require horizontal thrust from lift rotors, an aircraft configured according to the invention does not depend on propulsion from a vertical lift unit, since after deactivating its tandem rotors it is propelled in a direction parallel to the axis of symmetry by an independent propulsion system as used in today's most efficient aircraft.

[0061] Pivotally mounted around substantially vertical axes, the front and rear rotors are supported by bearing-equipped support structures aligned with the aircraft's axis of symmetry. These support structures, configured to provide mechanical strength, allow the front and rear rotors to lift and support the aircraft's weight safely, stably, and maneuverably under all rotary-wing flight conditions. The rotational planes of the two rotors are preferably coplanar, or the rear rotor is mounted above the front rotor's level line, and the longitudinal distance separating the areas of the two dynamic circles described by the tips of the front and rear rotary blades is at least the length of a wing root chord.

[0062] In preparation for a helicopter flight already on approach, a controller engages a rotational power source with the counter-rotating rotors via transmission and coupling mechanisms, which may be provided with gearboxes. Or, as mentioned, this can be done with a front and rear pair of coaxial hubs. Similarly, in preparation for an airplane flight from vertical flight, the controller disengages the rotational power source from the front and rear single-hub or coaxial rotors, which are then selectively decelerated by a rotor brake until their blades are parked at predefined positions.

[0063] Provided with masts comprising tabs or shoulders similar to pipe flanges, both the front rotor and its rear counterpart are supported by thrust or ball bearings supported on struts integral to the forward and rear fuselage sections, providing a suitable and secure operational connection to the front and rear rotors. Each rotor is provided with at least one hub of an unconventional design comprising cylindrical hinges that hold unconventional grips provided with also unconventional rotor blades. Although it is important to be firmly attached and supported by the grips in both helicopter and aircraft flight, the rotor blades of the invention are configured to be slid by an actuator during transition and conversion flights using the same grips that hold them firmly in fixed-wing and rotary-wing flight.

[0064] In a specific embodiment of single-hub rotors, each rotor comprises a pair of handles fitted with respective rotor blades, while in another embodiment, a coaxial rotor comprises a pair of two-blade, counter-rotating hubs, with four blades per rotor. By rotating in opposite directions, the blades of each coaxial rotor counteract the aforementioned lift dissymmetry that affects single-rotor helicopters. However, to counteract the asymmetric lift in embodiments with only two blades per rotor, in the absence of counter-rotating coaxial hubs, means are provided for the blades to cyclically flap up and down while rotating on opposite sides of the fuselage in straight-rotary flight.

[0065] In one embodiment, a rotor blade is inserted into a parallel rectangular grip hollowed out by a longitudinal cavity, linear motion bearings with raceways and rolling element cages arranged within the grip allow the rotor blade to slide longitudinally through the grip during transition and conversion flights. In another embodiment, instead of linear motion bearings, inner and outer race bearings, such as ball, roller, or needle bearings, are embedded on both sides of a grip, with their outer rotating races facing inward into the grip where a blade is housed. For For example, two bearings can be mounted, spaced longitudinally and centered perpendicularly on each side of the handle, so that the pair of bearings on one side matches a pair of counter-positioned bearings on the other side of the handle. With such an arrangement of four counter-positioned bearings in pairs, each rotor blade is sandwiched between two sliding bearing bases provided by the two pairs of counter-positioned bearings, which are longitudinally spaced at a distance suitable for the blade to be cantilevered across or firmly held by the handle in any flight condition.

[0066] In a specific embodiment of actuators that move the front and rear rotor blades through their respective grips during transition and conversion flights, the blades are provided with a magnetic induction motor system similar to the Maglev rail transit system. Since the blades do not need to be levitated like trains, but simply moved longitudinally through the grips, sets of superconducting electromagnets, fitted to both the blades and the grips, alternately attract and repel each other, causing the blades to slide sandwiched between bearings embedded in the grips. However, it should be understood that, without departing from the spirit of the invention, other systems and actuators can be provided, such as electric motors meshed with worm gears, which are known in the art and can longitudinally move a rotor blade housed in a grip sandwiched between bearings.

[0067] In one embodiment where the rotor blades are deactivated in transition flight and then arranged to provide good aerodynamic properties, at least one blade is positioned on the fuselage, while in another embodiment all the interrupted blades are used as fixed wings.

[0068] In another aspect, for both two-blade and four-blade rotor embodiments, in order to maintain the surrounding flow in laminar regime, a A blade edge reconfiguration system is used to convert the leading edges into trailing edges, and vice versa, on at least one front and one rear blade during a transition or conversion flight, the stages in which the aircraft is configured for the subsequent flight mode. Thus, after being left in autogyro and then selectively braked by a rotor brake device to a predefined rotational speed, the convertible blades of the invention have their leading and trailing edges inverted during rotor deceleration. Conversely, upon restarting in a conversion flight, their leading edges are reconfigured back to the rotary wing arrangement.

[0069] The two convertible aircraft that illustrate the various aspects and advantages of the invention are hybrid-electric, and one of them may be electric. In both cases, the front rotor is powered by an electric power unit housed in the nose of the aircraft, while the rear rotor is driven by a tail power unit, which may be electric, internal combustion, or hybrid. This arrangement of rotors with dedicated adjacent engines has the advantage of avoiding an interconnecting shaft along the fuselage intended to drive the front rotor. For example, the front rotor may be powered by at least one electric motor housed in the forward section of the fuselage, while the rear rotor is powered by a tail thermal power unit, which may be configured to also drive an attached or integrated electric generator and, possibly, a tail propeller.With such an engine arrangement, the generator can be configured to power one or each forward electric motor installed in the aircraft's nose. However, without deviating from the spirit of the invention, an interconnecting shaft similar to that of the Boeing CH-47 Chinook tandem helicopter can simultaneously drive the front and rear rotors from a power unit comprising at least one internal combustion engine housed in the rear fuselage.

[0070] Alternatively, or in addition, an electrical energy storage device, such as a battery or high-energy-density capacitor, may be provided for recharge by the in-flight generator or any other device on the ground. The battery may independently supply one or each electric motor driving the front rotor or supplement the generator. Power from the electrical energy storage device may be supplied to one or each front electric motor, for example, in the event of increased power requirements, such as during hovering or vertical takeoff. Additionally, the battery may be replaced or recharged on the ground after cooperating with the generator during a vertical landing.

[0071] Regarding sustained and controlled fixed-wing and empennage flight, the flight control mechanisms of the convertible aircraft proposed by the invention may be identical to those of a conventionally designed aircraft and, therefore, will not be discussed. For flights in a rotary-wing configuration, obviously neither pitch nor roll are movements of the aircraft of this specification to be considered. Therefore, only the yaw movement in helicopter mode remains, which can be obtained as a reaction torque exerted on the fuselage in response to the differentiated operation of the rotors, a well-known operation performed by a controller autonomously managed by an electronic microcontroller. Alternatively, or in addition, yaw movements may be provided by a ventilation system comprising at least one electrically or mechanically driven tail fan.

[0072] For aircraft of this specification with two blades per rotor, the tail rotor blades rotate clockwise when viewed from above, while the front rotor blades rotate counterclockwise, as previously mentioned. With these synchronized rotational directions for single-hub rotors, each blade pass through the leading edge of the front rotor corresponds to a blade pass through the trailing edge of the tail rotor on the opposite side of the fuselage.

[0073] Furthermore, it should be appreciated that the exemplary turbofan aircraft of this specification is equipped with thrust vector control nozzles for up to 90 degrees from the horizontal, not thrust reversers. As stated above, both the nozzle and the thrust reverser of the invention are capable of providing a duct with an adjustable tubular bend within a vertical plane downstream of an engine exhaust, both capable of directing thrust at angular intervals up to 90 degrees from the horizontal. Although, as already discussed, the thrust vector control nozzle is sufficient for helicopter flight, a thrust reverser instead of a thrust vector control nozzle for up to 90 degrees has the advantage of enabling the aircraft with redundant horizontal landing in addition to the standard vertical landing.Therefore, if desired in some applications, thrust reversers for turbine engines can be provided, as they are capable of adjusting the direction of thrust generated by the engine for both vertical flight and horizontal landing.

[0074] It will also be appreciated that the two exemplary aircraft of this specification are provided with a high gull-wing fuselage configuration, which is typically positioned above the level line of the nose rotor's rotation plane, such that, from a certain forward speed, the wing temporarily flies over the downwash or downdraft deflected by the nose rotor blades, which rotate below the level line of the fixed wing. The combination of such a nose rotor arrangement with the fixed wing system of the invention is expected to be useful in transition and turning flights due to the aerodynamic interaction of the wing with the air volume deflected by the nose blades.

[0075] As mentioned in the chapter dedicated to the state of the art, conventionally designed helicopters have never been able to fly as fast as airplanes. Having been invented almost a century ago and their first prototype flown for the first time in 1941, even with the advent of turboshaft engines, their cruising speed has been limited to just over 150 knots for decades. Among the causes of their poor performance is the aforementioned lift imbalance, which, despite all recent technological advances, prevents them from The best and most sophisticated helicopters today, such as the Italian Agusta AW169 and the American Sikorsky S-92 and Bell 525, fly faster than 165 knots.

[0076] Another architectural constraint that has been challenging in the aeronautics field concerns the aforementioned tilt rotors. Although their cruise performance can be considered satisfactory when compared to that of a single-rotor helicopter, the aircraft with large propellers incorporated into the tips of a fixed wing, which has its most successful version in the US military model known as the V-22 Osprey, flies far below the cruising speeds of modern turbofan aircraft. In other words, in terms of cruise flight, the tilt rotor flies faster than a helicopter but much slower than a turbofan system.

[0077] Therefore, although the twin tilt-rotor design arose with the definite purpose of designing an air vehicle that could provide both the vertical flight capabilities of a helicopter and the high speeds of an airplane, strictly speaking this never happened, since the two tilt-rotor wingtip propellers were capable of achieving all the vertical capabilities of a helicopter, but not the higher speeds of an airplane, at least not in terms of the high-speed performance of contemporary turbofan aircraft.

[0078] In contrast, the aeromechanical configuration of the convertible aircraft with tandem rotors of the nature described will be the first to achieve the purpose that has inspired and continues to inspire inventors and aircraft manufacturers around the world for almost a century, namely: from the drawing board to the market, to design an aerial vehicle that combines the agility provided by the vertical flight capabilities of the best helicopters combined with the high cruising speeds and range of today's fastest and most efficient aircraft.

[0079] Given the above, given the performance and limitations of the prior art aircraft discussed, the objective of the invention is to provide an aircraft convertible with tandem rotors that, due to its unique aeromechanical configuration and flight parameters, is capable of providing capabilities and solutions, among which the following can be highlighted as the most relevant: a rotor area considerably larger than current ones, or even larger than the largest of all, which is that of a conventionally designed helicopter, leading to a correspondingly lower disk load and a proportional reduction in fuel consumption, net emissions and noise footprint; the ability to fly, both in transition and conversion, at a level of stability and safety never before achieved by any convertible aircraft, taking into account the cooperation between the fixed and rotary wing lift means during such transitional stages of flight, in addition to the advantages arising from the operational independence of the propulsion and vertical lift units, an attribute of the unique architecture of the aircraft proposed by the invention;elongated spacing between the nose and tail lift rotors to provide a wider center of gravity range and a longitudinal balance also not yet demonstrated by any aerial vehicle in vertical and hovering flight (the only exception is the Boeing CH-47 Chinook tandem helicopter, which, however, is limited in many respects when compared with the convertible aircraft of the invention), since, as is known, conventionally designed helicopters are lifted into flight from a single lifting point on the fuselage, whereas twin tilt-rotor aircraft, although they are lifted by the tips of a wing, in practice it is as if they were lifted from a single lifting point, since such lifting points extend in the perpendicular direction and not along the fuselage;capabilities only found in tandem configurations for movement in weather, altitude and crosswind conditions that normally prevent conventional helicopters from flying, in addition to the stability resulting from the operational independence of the propulsion and yaw means in vertical flight; cruise efficiency never achieved by any other VTOL aircraft, being identical to that of the best modern aircraft; since the cruise flight parameters of the invention are comparable to those of a prior art turboprop or turbofan system; fuel efficiency in both helicopter and airplane mode due to the aforementioned low disk load in helicopter mode and aerodynamic drag in cruise flight compatible with that of the most efficient airplanes today; remarkably low stall speed, since in airplane flight the rotary wings of the invention provide extra lift operating as fixed wings; vertical and hovering flight capability free from the impact of downwash on the wing (it is estimated that the V-22 Osprey loses about 10% of its power to the downwash of the rotors on the wing in helicopter flight); ability to fly in VTOL mode without anti-torque tail rotors, which, as is known, are mandatory in conventional helicopters and also demand around 10% of the power of their powertrain;alternative or redundant yaw control capabilities in helicopter mode, one of them through electric or mechanical fans, which can be configured in a manner dedicated to the part of the aircraft's powerplant; a thrust vector control nozzle for turbine engines considerably lighter and simplified than the only known thrust vector control nozzle, Rolls-Royce LiftSystem, which equips the aforementioned North American fighter F-35B; and a thrust reverser for turbine engines capable of reversing 100% of the turbine jet during the deceleration of the convertible aircraft of the invention in an alternative horizontal landing or, even, for an airplane of conventional design.;

[0080] These and other advantages, aspects and characteristics of the invention will become more evident from the description of preferred operational configurations, given solely as examples of embodiment and not restrictive in any respect, which will be appreciated in connection with the attached drawings and the claims that accompany them.

[0081] FIGS. 1-18 relate to a small turboprop hybrid-electric, or electric-only, aircraft capable of flying in both rotary-wing and fixed-wing configurations, hereinafter referred to as “convertible aircraft 100,” which is illustrated in rotary-wing flight in FIGS. 1-3, 5-6, 8, and 16 and in fixed-wing flight in FIG. 17. FIG. 4 addresses a front rotor strut 115 of convertible aircraft 100, while FIGS. 5-7 emphasize a front rotor 150 and its collective pitch control mechanism 158. FIGS. 8-11 illustrate two examples of embodiments of rotor masts 151, 152 supported by a pair of counter-rotating supports 151c, 152c provided with bearings (not shown) which, combined with a flexible suspension system assisted by a set of elastic elements or springs 151e, 152e (FIGS.10-11), allow the mast 151, 152 to tilt as a result of a rotor blade 156, 157 cyclically flapping upwards in the relative wind, while the opposite rotor blade 156, 157 of the same rotor hub 154 flaps downwards, in order to counteract the so-called lift dissymmetry in the convertible aircraft 100 in rotary wing flight (FIG. 8). FIGS. 12-13 illustrate an exemplary embodiment of a pair of handles 155 configured to support respective rotor blades 156, 157 sandwiched between bearings (not shown). FIGS. 14-15 are cross-sections of two preferred embodiments of a convertible blade, i.e., a blade capable of alternating its leading and trailing edges during flight, hereinafter referred to as “rotor blade 157,” while FIGS. 16-18 illustrate the rotor blade 157 of FIG. 15 and a non-convertible blade, hereinafter referred to as “rotor blade 156.”

[0082] Referring first to FIG. 9, a fuselage 110 of convertible aircraft 100 in rotary wing flight is revealed in a front view, where for clarity the rear rotor 150 is not illustrated. Behind the forward rotor support 115 (115a, 115b) provided with the mast 151, both in transparency, a central roof portion of convertible aircraft 100 is seen higher than the same roof portion of the prior art. Referred to as angled longitudinal apex 114, such roof portion projects upward about the axis of symmetry to the along the fuselage 110 is intended to improve the flow of air flow diverted downwards by the aerodynamic action of the rotor blades 156, 157 or downwash that impacts on the fuselage 110 in rotary wing flights.

[0083] As discussed in FIG. 1, convertible aircraft 100 comprises a forward section 111, a midsection 112, and an aft section 113 of fuselage 110, a gull wing system 120, and an inverted 'V' tail assembly provided with an empennage 130 (FIG. 3). A vertical lift / propulsion unit comprises an internal combustion engine referred to as engine 140, transmission and coupling mechanisms (not shown), an electric generator (not shown) mechanically connected to or incorporated in engine 140, at least one electric motor (not shown) housed in front section 111, two rotors 150 in tandem, which rotate synchronously in opposite directions, and a tail propeller 143 centered at the end of rear section 113. The rear rotor 150, the electric generator and the tail propeller 143 are connected with engine 140 by transmission and coupling mechanisms, which may be provided with at least one gearbox (not shown).

[0084] The empennage 130 comprises in its central portion a horizontal stabilizer 131 extended laterally in the form of a pair of tilted stabilizers 132, which are directed downward and provided with movable directional control surfaces or tilt rudders 134 useful in airplane flight. A pair of yaw control fans 116, either electric or driven in rotation by the engine 140, is illustrated in FIGS. 1 and 3 with their pair of sliding doors 117 (one door not shown) open for possible fan operation in helicopter mode. The open sliding doors 117 indicate that the convertible aircraft 100 flies on rotary wings and that the fans 116 are available for yaw movements while the horizontal speed is insufficient for directional control by the tilt rudders 134.

[0085] The front rotor support 115 and its rear counterpart are configured to provide mechanical strength to the connections of the front and rear rotors 150 to the convertible aircraft 100, with the rear rotor support 115 being embedded in the rear section 113 of the fuselage 110. FIG. 4 illustrates the front rotor support 115 comprising a pair of radially flattened cylindrical pylons 115a, which are symmetrically tapered at the leading and trailing edges so as to provide good aerodynamic properties. Integrated at their lower ends with the front section 111, the pylons 115a are braced at their upper ends by a first beam 115b also configured to provide good aerodynamic properties. A second beam 115c of rectangular cross-section connects the beam 115b to the roof of the convertible aircraft 100 in the form of a T.

[0086] The front rotor support 115 should not, however, be considered too strictly as just described, but merely as another example of an embodiment or means for supporting the front rotor 150. Therefore, without departing from the scope of protection, another type of support, this time in the form of a column centered on the axis of symmetry of the forward section 111 of the fuselage 110, could be provided for the same function. For example, a one-piece support could extend symmetrically upward from the nose and from there to an inclined column between windshields projecting to a first portion of the roof of an aircraft, as is the case with the front rotor support 115. Such an alternative embodiment of a one-piece rotor support is expected to provide greater rigidity and consequently less vibration to the front rotor 150 compared to the column-and-beam rotor support 115 discussed.Furthermore, on an aircraft that does not have a well-defined nose, its front rotor may be supported directly on a forward fuselage section and a separate structure, such as the rotor supports mentioned, may not be necessary.

[0087] As already noted, the front and rear rotors 150 rotate synchronously in opposite directions about substantially vertical axes supported by corresponding front and rear rotor supports 115, which are mounted on the axis of symmetry of the convertible aircraft 100, respectively above the front section 111 and embedded in the rear section 113. In the example embodiment of the rotor 150, each rotor is provided with two blades, one being a non-convertible rotor blade 156 and one being a convertible rotor blade 157. As appreciated in FIG. 2, the front and rear rotors 150 of the convertible aircraft 100 are separated from each other by such a distance along the fuselage 110 that the two dynamic circles described by the tips of their front and rear rotating rotor blades 156, 157 are spaced by at least the length of a wing root chord.

[0088] The internal combustion engine 140 of the convertible aircraft 100 is a turboshaft engine, which is a turbine engine configured to provide shaft power rather than jet thrust. The aft section 113 comprises inlet structures with two side openings 141 for air intake to the engine 140 (FIG. 3), which as noted comprises an output shaft (not shown) configured to drive a transmission and coupling mechanism that may comprise a gearbox (not shown). Provided with two twin exhausts 142, the engine 140 is configured to drive the tail rotor 150 about its substantially vertical axis, as well as to power or disengage the tail propeller 143 centered at the aft end of the fuselage 110.

[0089] One or each electric motor housed in forward section 111 is connected by electrical cable (not shown) to the generator housed with engine 140 in aft section 113. As discussed, aft rotor 150 is driven in rotation by transmission and coupling mechanisms, in turn powered by engine 140, which also powers the adjacent or incorporated generator and tail propeller 143. Meanwhile, front rotor 150 is driven in rotation by one or each electric motor housed in forward section 111, in turn supplied by the generator housed in aft section 113, which, as noted, is powered by the adjacent internal combustion engine 140. Alternatively, or in addition, front rotor 150 may be powered by engine 140 through an interconnecting shaft (not shown) disposed along fuselage 110.

[0090] As already discussed, the convertible aircraft 100 may alternatively be provided with an electrical energy storage device, such as a battery or a high-energy-density capacitor (not shown), which is recharged by the generator in flight, another device on the ground, or both. The battery may independently power the motor that drives the nose rotor 150 or do so in cooperation with the generator. In such an alternative operational configuration, the electrical energy storage device's power supply to the motor that drives the nose rotor 150 may be related to a possible increase in power requirements, such as during hovering or vertical takeoff, and the electrical generator may recharge the battery during flight, or the electrical energy storage device may assist the generator during landing and then be recharged or replaced on the ground.

[0091] FIG. 6 is an enlarged view of FIG. 5 to better illustrate the front rotor hub 154 and its counter-axled cylinders 154a, although without cylindrical hinges 155a of the grips 155 and hub fairing 154c. The collective pitch control mechanism 158 is provided with a concentric yoke 158a comprising a telescopic central rod intended to be driven in vertical movements by a hydraulic actuator (not shown) and two toothed side rods, which are engaged with respective toothed rings of the cylindrical hinges 155a of the grips 155 (FIG. 7). A blade root shoulder 156r, 157r, as seen at right, is but one example embodiment or means for holding rotor blades 156, 157 in their respective grips 155 against the centrifugal forces of rotary wing flight.This is necessary because a rotor blade according to the invention must either be firmly held in a grip 155 or be free to slide through the same grip 155 that holds it sandwiched between bearings (not shown). Alternatively, locking of the rotor blades 156, 157 in. corresponding grips 155 against centrifugal forces may be provided by other known means, such as hydraulic pins.

[0092] The concentric yoke 158a is shown in full length in FIG. 7, where for instructive purposes the pair of cylinders with opposing shafts 154a, the hub fairing 154c and one of the two cylindrical hinges 155a of the handle 155 seen at the left are not illustrated. Perpendicularly integrated with the upper end of the mast 151 is the pair of cylinders with opposing shafts 154a (FIG. 6), which are nothing more than two twin cylinders joined side by side in a single piece, each cylinder being provided at the ends with shafts aligned parallel to the handles 155. As already explained, each rotor blade 156, 157 is sandwiched between bearings embedded in the corresponding handle. 155, the lateral edge of which facing the center of the rotor hub 154 is parallelly integral with a pair of aligned spaced-apart hollow cylinders, referred to above as cylindrical hinges 155a, which are supported in bearings 154b of the aligned shaft pair of each counter-axle cylinder 154a, as illustrated in FIG. 6. So that the collective pitch of the rotor blades 156, 157 is changed whenever the grips 155 are tilted about the aligned shafts of the counter-axle cylinder pair 154a or rotor hub 154.

[0093] FIG. 8 illustrates the front and rear rotor blades 156 of convertible aircraft 100 being lifted by the upstream horizontal wind on opposite sides of the fuselage 110, while the rotor blades 157 are lowered downstream, which allows us to conclude that the rear rotor 150 rotates clockwise while the front rotor 150 rotates counterclockwise, as viewed from above. As already mentioned, in horizontal flights initiated at least partially by rotary wings, coaxial hubs do not require any means to counteract the so-called lift dissymmetry, since by rotating synchronously in opposite directions, their counter-rotating coaxial blades equalize the lift on both sides of the fuselage. However, for single-hub rotors 150 provided with two rotor blades 156, 157 of the convertible aircraft 100, means are employed to combat the mentioned lift dissymmetry, which is known to begin at a certain horizontal speed in direct flights in helicopter mode.

[0094] Revisiting FIG. 9, where for the sake of clarity the rear rotor 150 is not addressed, a first example of an embodiment of said flexible suspension system of the mast 151 is seen through the transparency of the front rotor support 115, which is provided with the beam 115b comprising a central casing intended to coaxially house the components of the flexible suspension system assisted by said elastic elements or springs 151e. As already mentioned, in order to counteract the so-called lift dissymmetry in the convertible aircraft 100 in horizontal rotary wing flights, the front and rear masts 151 alternately tilt towards the sides of the fuselage 110 by the aerodynamic action of the front and rear rotor blades 156, 157, which are cyclically lifted by the relative upstream wind.Intermittent tilting of mast 151 is a known expedient used to counteract the lift dissymmetry that affects non-coaxial rotorcraft above a certain horizontal speed. The image shows a drive shaft 145 connecting mast 151 to an electric power unit (not shown) housed in the nose of convertible aircraft 100. As already discussed, alternatively or in addition, front mast 151 may be driven by an interconnecting shaft (not shown) that, like a counterpart rear drive shaft 145, may be powered by engine 140 housed in the rear section 113 of fuselage 110 (FIG. 3). Front drive shaft 145, its rear counterpart, and the interconnecting shaft may be configured to brake front and rear rotors 150 until they are stopped at predefined positions during transition flights.

[0095] FIG. 10 is an enlarged perspective view taken from a front-to-side angle of the exemplary embodiment of the mast 151 discussed in connection with FIG. 9. Integrated with the beam 115b (not shown in FIG. 10) is a load support 151a in the form of a hollow cylinder supported on a bearing (not shown) that operatively supports a cylindrical bevel gear 151b, viewed from the front. sectioned by radial cuts that suppress % of its annular body. The mast 151 is tiltably supported by bearings (not shown) provided on the pair of opposing swivel supports 151c, in turn supported on the bevel cylindrical gear 151b. So, as appreciated in FIG. 9, the beam 151b supports the load support 151a, which operatively supports the bevel cylindrical gear 151b, which supports the pair of opposing swivel supports 151c (only one opposing swivel support 151c is seen in FIG. 10), which support the mast 151, which is tiltable within a tilting space radially internal to both the load support 151a and the bevel cylindrical gear 151b.

[0096] In addition to being tiltably supported by the opposing swivel brackets 151 c as discussed, the mast 151 is also supported by an inner tube 151 d inserted therein which is provided with at least one bearing, such as a double row ball bearing (not shown), intended to operationally support the mast 151. A non-inserted lower portion of the inner tube 151 d is seen in FIG. 10 comprising four inclined flanges or tabs supported on two pairs of elastic elements, a first pair being in the form of two long or lateral springs 151 e and a second pair being in the form of two short or central springs 151 e. Supported on a spring base or support 151 f, the general shape of which is that of a cylindrical plate integrated with the beam 115 b (not shown in FIG. 10), the central springs 151 and being aligned with the fuselage 110 and the lateral springs 151 and being perpendicular.Such an operational configuration of springs 151 both allows greater amplitude for the blades to strike the sides of the fuselage 110 and prevents them from touching the roof of the convertible aircraft 100.

[0097] FIG. 11 is an enlarged perspective view taken from a front-to-side angle of a second example of a mast 152 embodiment that, like the homologous mast 151 discussed, tilts to counteract the so-called lift dissymmetry from a certain forward speed of the convertible aircraft 100. A pair of long side springs 152e of this second example of The embodiment is identical to the pair of springs 151 and long sides of the first embodiment of FIGS. 9-10. However, in place of the short springs 152e of the first embodiment, a mast base axle 152g integrated into the lower edge of an inner tube 152d is engaged with bearings provided in two opposing columns supported by a spring support 152f, in turn integrated into the front rotor support 115. Such a flexible suspension arrangement allows the mast 152 to tilt when the rotor blades 156, 157 rotate along the sides of the fuselage 110, but not over the roof of the convertible aircraft 100.

[0098] FIGS. 12-13 illustrate an electric variant of the convertible aircraft 100. In a side perspective, FIG. 12 shows the nose 111 of the convertible aircraft 100 with a nose propeller 144 powered by an electric motor (not shown) housed in the nose, while in an enlarged side elevation, FIG. 13 illustrates in profile the front rotor 150 with its blades feathered or substantially horizontal at zero pitch. The electric convertible aircraft 100 is identical to the hybrid-electric convertible aircraft 100 described in nearly all respects except for the powertrain: instead of an internal combustion engine and at least one electric motor, the forward section 111 and the aft section 113 of the fuselage 110 house at least one electric motor (not shown); and instead of just one tail propeller 143, electric convertible aircraft 100 is provided with two propellers: nose propeller 144 and tail propeller 143 (not shown).

[0099] Since it does not have a thermal power unit like that found in the hybrid-electric convertible aircraft 100, the electric convertible aircraft 100 must obviously be provided with electrical energy storage devices, such as high-energy-density batteries or capacitors (not shown). As in the hybrid-electric convertible aircraft 100, power units housed in both the forward section 111 and the aft section 113 of the fuselage 110 engage / disengage respective counter-rotating front and rear rotors 150 via transmission and coupling mechanisms (not shown). But unlike the described convertible aircraft 100, in the aircraft electric convertible 100 one or each electric motor (not shown) housed in the forward section 111 drives in rotation the front rotor 150 and the nose propeller 144, while one or each electric motor (not shown) housed in the rear section 113 drives in rotation the rear rotor 150, the tail propeller 143 and eventually a pair of yaw control fans 1 16 (not shown).

[0100] The rotor blades 156, 157 of the tandem rotors 150 of the invention are configured to be stopped, centered, and locked in their respective grips 155 in transition flight or slid until their roots are fully inserted and locked in the same grips 155 in conversion flight. To support the rotor blades 156, 157 sandwiched between rolling elements, two bearing systems embedded in the respective grips 155 are disclosed. In the hybrid-electric convertible aircraft 100, linear motion bearings (not shown) are provided, while in the electric convertible aircraft 100, instead of linear bearings, each grip 155 comprises four inner and outer race bearings counterposed in pairs, the transversely centered and longitudinally spaced positions of which can be appreciated in FIG.12, taking into account that the four upper bearing fairings 155b illustrated correspond to four other opposing lower bearing fairings 155b, which are not seen in the image.

[0101] The forward convertible rotor blade 157 is illustrated in FIG. 12 outside its housing to show the profile of the handle 155 outlined internally by the longitudinal cavity housing the rotor blade 157, as well as to address the general appearance of the rotor blade 157 viewed as a whole in a fixed-wing configuration. Note that, longitudinally, the rotor blade 157 comprises a midsection or longitudinally inner section 157j and two side sections or longitudinally outer sections 157k, which are configured to invert their leading and trailing edges during flight. Thus, in rotary-wing flight, the longitudinally outer sections 157k maintain the same edge arrangement as the longitudinally inner section 157j, which, as is well known, is not convertible. However, during the transition from flight to the fixed wing configuration, the leading edges of the longitudinally outer sections 157k are inverted and are as shown in the image, where the profile of the longitudinally inner section 157j is seen with the same design as the longitudinal cavity formed in the handle 155, shown just above the mast 151, and the profile of the two longitudinally outer sections 157k is depicted with the leading edges facing the direction of flight.

[0102] Revisiting FIG. 13, an enlarged side elevation shows how the two handles 155 of one of the rotors 150, in this case the front rotor 150 mounted on the rotor support 115, have different profiles, one handle 155 having a rounded edge, such as a leading edge, and the other having a tapered edge in the form of a trailing edge. The image also shows the blades flattened at zero pitch, which gives the assembly of handles 155 and rotor blades 156, 157 a substantially horizontal overall appearance. Profiled from left to right in the figure are: a first pair of upper and lower bearing fairings 155b; the longitudinally outer section 157k; a portion of the longitudinally inner section 157j seen fully housed in the handle 155 behind the longitudinally outer section 157k; a pair of cylindrical hinges 155a; the concentric yoke 158a; the blade root shoulder 156r; and a second pair of upper and lower bearing fairings 155b.

[0103] FIG. 14 is a cross-section of one of the two longitudinally outer sections 157k of a first embodiment of rotor blade 157 configured to convert its leading edges 157a to trailing edges 157b, and vice versa, during flight. Note that longitudinally inner section 157j is not shown in cross-section. Extending in length from the root to the tip of rotor blade 157 is a transversely symmetrical spar box-type support member 157c. Spar box 157c in each longitudinally outer section 157k is covered by an unbonded upper skin 157d of flexible sheet metal spliced ​​laterally to a lower skin 157e of rigid sheet metal, in turn secured along spar box 157c. by a symmetrically centered longitudinal hinge 157f—the longitudinally outer section 157k, the lower skin 157e, and the upper skin 157d, which is considerably wider than the lower skin 157e, are of the same length. During an edge inversion, magnetic actuators (not shown) cause first longitudinal portions of the upper skin 157d and lower skin 157e to be adhered to the respective upper and lower faces of a same symmetrical side of the stringer box 157c in each longitudinally outer section 157k. With the simultaneous displacement of said first longitudinal skin portions, a second longitudinal portion of the upper skin 157d is bent and, simultaneously, a second longitudinal portion of the lower skin 157e is moved away from the stringer box 157c, as appreciated in the figure.That is, magnetic actuators (not shown) invert the leading edges of the convertible rotor blades 157 for the subsequent flight mode of the convertible aircraft 100 by simultaneously adhering longitudinal collateral portions of both the upper skin 157d and the lower skin 157e to the spar box 157c at each longitudinally outboard section 157k of the convertible rotor blade 157.

[0104] FIG. 15 is a cross-section of one of the two longitudinally outer sections 157k of a second embodiment of rotor blade 157 configured to convert its leading edges 157g to trailing edges 157h, and vice versa, during flight. Note that the longitudinally inner section 157j is not shown in cross-section. As in the embodiment shown in FIG. 14, a transversely symmetrical spar box 157i extends in length from the root to the tip of the rotor blade 157. But unlike the longitudinally outer section 157k just described, the longitudinally outer section 157k of this second embodiment of the rotor blade 157 is covered by an upper skin 157m and a lower skin 157p adhered to the spar box 157i, which is provided with lateral support members 1571. In addition, the leading edge 157g and the trailing edge 157h are two twin appendages provided with hinges (not shown) attached to opposite symmetrical sides of each spar box 157i of the longitudinally outer sections 157k—the longitudinally outer sections 157k, the upper skin 157m, the lower skin 157p, the lateral support members 157l, the twin appendages and the hinges being of the same length. The twin appendages rotate with said counterposed hinges about axes parallel to the rotor blade 157, so that in each longitudinally outer section 157k one appendage provides a leading edge 157g when retracted, while the other is extended to provide a trailing edge 157h.In addition to the twin leading edge appendages, each longitudinally outboard section 157k is provided with another pair of twin appendages 157n, which are nothing more than an extension of the upper skin 157m in the form of a pair of longitudinal plates attached by flexible hinges (not shown) to opposite symmetrical sides of the spar box 157i on each longitudinally outboard section 157k—the longitudinally outboard sections 157k, the twin appendages 157n, and the hinges being of the same length. The figure shows how the leading edge 157g retains and the trailing edge 157h releases the appendage 157n, which returns to its extended position when rotated by an elastic element (not shown) incorporated therein.

[0105] FIGS. 16-18 address an exemplary embodiment of the front rotor 150 provided with the non-convertible rotor blade 156 and the convertible rotor blade 157 of FIG. 15, which are seen locked to their respective grips 155 in rotary wing flight in FIG. 16 and centered and locked to the same grips 155 in fixed wing flight in FIG. 17. The views are two perspective views taken from a side angle showing a blade root shoulder 156r and an actuator 157q at the boundary of the longitudinally inner section 157j with one of the longitudinally outer sections 157k of the rotor blade 157. convertible, comprising interchangeable leading edge 157g and trailing edge 157h, as already explained. Note that the non-convertible longitudinally inboard sections 157j of the front and rear rotor blades 157 serve as airfoils only during rotary wing flight (FIG. 16). However, when the rotor blades 157 are centered with their longitudinally inboard sections 157j fully housed and locked into the corresponding grips 155 at the end of a transition flight, it is the grips 155 and the longitudinally outboard sections 157k that become airfoils, this time in a fixed wing arrangement as illustrated in FIG. 17.That is, while the rotors 150 are being decelerated while still in transition flight, the leading edges of the longitudinally outboard sections 157k are inverted and the four rotor blades 156, 157 of the convertible aircraft 100 are centered and locked with the longitudinally inboard sections 157j of the front and rear rotor blades 157 fully housed in their respective grips 155. Once inverted, the leading edge 157g and trailing edge 157h assume the same orientation as the leading and trailing edges in the grips 155 (FIG. 13), which are programmed to be stopped and locked in a fixed wing configuration for the airplane flight that is about to commence.

[0106] Through a transparent enclosure, the enlarged view of FIG. 18 addresses the same actuator 157q as in FIG. 17, seen adjacent to the handle 155 shown forward in the direction of flight. Actuator 157q is a rotational power source, such as an electric motor, provided at its ends by worm gear shafts meshed with parallel shafts on opposite, symmetrical sides of spar housing 157p (not shown). The leading edge 157g and trailing edge 157h of the two longitudinally outer sections 157k are reversed whenever actuator 157q rotates in the same direction along the parallel shafts, which, as seen in FIG. 18, intersect the longitudinally outer section. inner section 157j to invert the edges of the longitudinally outer section 157k not adjacent to the actuator 157q (FIGS. 17-18).

[0107] FIGS. 19-30 relate to an unmanned twin-engine turbofan hybrid-electric aircraft capable of flying in both rotary wing and fixed wing configurations, hereinafter referred to as “convertible aircraft 200,” which is illustrated in rotary wing flight in FIGS. 19 and 21, in transition or conversion flight in FIG. 22, and in fixed wing flight in FIG. 23. Like the convertible aircraft 100 just described, the convertible aircraft 200 comprises a fuselage 210 with a forward section 211, a middle section 212, and a rear section 213. A gull wing system 220 equipped with a pair of winglets 221 and a tail assembly provided with an empennage 230 are symmetrically coupled to the middle section 212 and rear section 213 of the fuselage 210, respectively.A vertical lift / propulsion unit comprises a pair of twin turbofan engines 240, transmission and coupling mechanisms (not shown), an electric generator (not shown) mechanically connected to or incorporated into the turbofan engines 240, and at least one electric motor (not shown) housed in the forward section 211 of the fuselage 210.

[0108] A front rotor support 215 and a rear rotor support 250 are configured to provide mechanical strength to the connections of a pair of front and rear coaxial rotors 250 to the fuselage 210. As in the convertible aircraft 100, the rear rotor support 215 is built into the rear section 213. The front rotor support 215 comprises a single-piece column aerodynamically tapered at the leading edge and symmetrically integrated with the fuselage 210 from the front section 211 or nose to a first roof portion of the convertible aircraft 200 (FIG. 20). Each front and rear coaxial rotor 250 comprises a pair of superimposed rotor hubs 254 configured to operate in counter-rotation, a lower hub being provided with a pair of non-convertible rotor blades 256 and an upper hub being provided with a pair formed by a rotor blade 256 and a convertible rotor blade 257.

[0109] Mechanisms 258, 259 for controlling the collective pitch of the front coaxial rotor 250 are illustrated in a front-to-side perspective of the convertible aircraft 200 in FIG. 20, where for clarity some components of the front coaxial rotor 250 are not shown, namely cylinders with counter-axles 254a, hub fairings 254b, handles 255 with respective cylindrical hinges 255a, non-convertible rotor blades 256, and the convertible rotor blade 257.

[0110] As already mentioned, each coaxial rotor 250 of convertible aircraft 200 is provided with two rotor blades 256 on the lower rotor hub 254 and one each on the upper rotor hub 254 (FIG. 19). The collective pitch of the upper rotor blades 256, 257 is controlled by a concentric yoke 258a, as seen at the top of FIG. 20, comprising a telescopic central rod and two counter-positioned toothed side rods. The mechanism of the concentric yoke 258a is identical to that of the concentric yoke 158a of convertible aircraft 100 and therefore will not be discussed in detail in this detailed description of the coaxial rotor 250. [0011 1] As seen in FIG. 20, two masts 251, 253 of coaxial rotor 250 are concentric tubes, the inner tube being mast 251 of upper rotor hub 254 and the outer tube being mast 253 of lower rotor hub 254. A concentric yoke 259a comprises two counter-positioned toothed lateral rods extending vertically from an upper ring 259b provided with a bearing (not shown), in turn supported on a lower ring 259c comprising three equidistant cylinders 259d extending vertically downward, which are actuated by a hydraulic actuator (not shown) housed in rotor support 215. As in helicopter rotor swash plates, lower ring 259c is stationary, or non-rotating, and upper ring 259b is rotatable. FIG. 20 does not show it, but like the toothed shanks of the concentric yoke 158a discussed in connection with FIG.7, the toothed rods of both the concentric yoke 258a and the concentric yoke 259a are engaged with corresponding toothed rings of cylindrical hinges 255a integrated with the handles 255. From. so that the collective pitch of the lower rotor blades 256 of the coaxial rotors 250 is changed whenever the concentric yoke 259a is actuated in vertical movements to rotate the cylindrical hinges 255a integrated with the lower handles 255 provided with the lower rotor blades 256.

[0112] In a side elevation, FIG. 21 illustrates the empennage 230 comprising an aerodynamic stabilizer, in the form of a horizontal stabilizer 231, and a vertical stabilizer 233. The horizontal stabilizer 231 is seen just below the coaxial rotor 250 comprising a movable horizontal surface or elevator 235 for controlling the pitch of the convertible aircraft 200 in airplane mode in the well-known manner. The vertical stabilizer 233 is in the form of a substantially vertical structural extension of the fuselage 210, which extends about the axis of symmetry of the rear section 213 and comprises a movable directional control surface or rudder 234 for providing yaw control in airplane mode.The figure also shows a yaw control fan 216, either electric or powered by the twin turbofan engines 240, with its sliding doors 217 open (one door not shown), and a thrust vectoring nozzle 10, which is seen diverting thrust vertically downward from a propeller nozzle of the left turbofan engine 240. In the illustrated condition, the convertible aircraft 200 flies on rotary wings.

[0113] FIGS. 22-23 are perspective views of the convertible aircraft 200 in transition and fixed-wing flight, respectively. In practice, FIG. 22 could also represent a conversion flight, as the hubs of the front and rear coaxial rotors 250 are seen interrupted with the eight rotor blades 256, 257 centered on the corresponding handles 255, as in preparation for helicopter flight. The edges of the convertible rotor blades 257 of the upper front and rear hubs are already inverted for airplane mode, and the lower rotor blades 256 of the two coaxial rotors 250 can already be slid toward the gull wing 220 by a magnetic actuator or an electromechanical system (not shown).

[0114] FIG. 23 illustrates a subsequent flight of the convertible fixed-wing aircraft 200 in an operational configuration in which the rotor blades 256, 257 of the upper hubs of the front and rear coaxial rotors 250 serve as auxiliary fixed wings configured for airplane flight and the rotor blades 256 of the lower hubs remain retracted and inoperative until rotary-wing flight is requested.

[0115] It is worth recalling that the two hybrid-electric convertible aircraft 100, 200 are examples of embodiments with at least one thermal power unit housed in the rear section 113, 213, which also houses at least one adjacent or incorporated electric generator, while the front section 111, 211 houses at least one electric motor configured to drive in rotation the single-hub rotor 150 and the coaxial rotor 250, both of which are located at the front. Like the internal combustion engine 140 of the convertible aircraft 100 discussed, the two twin turbofan engines 240 of the convertible aircraft 200 comprise output shafts (not shown) that drive transmission and coupling mechanisms provided with at least one gearbox (not shown).As in the hybrid-electric convertible aircraft 100, the transmission and coupling mechanism of the convertible aircraft 200 is configured to drive in rotation the rear coaxial rotor 250 about substantially vertical concentric axes, as well as a yaw control fan 216, when this is not electric, and eventually an interconnecting shaft with the front coaxial rotor 250.

[0116] The left turbofan engine 240 of the convertible aircraft 200 will now be discussed in perspective in FIGS. 24-25, which illustrate an exemplary embodiment of a rotational power transmission system from the pair of twin turbofan engines 240 operatively integrated into the rear section 213 of the fuselage 210. The same image of a front fan or fan ducted through a nacelle and provided with a shaft fairing 246 depicted in FIG. 24 is seen enlarged in FIG. 25, where an output shaft 244 is appreciated through the shaft fairing 246 illustrated in transparency. Engaged with the output shaft output 244 is a transmission shaft 245, which is configured to transmit rotational energy to transmission and coupling devices intended to drive in rotation the rear masts 251, 253, at least one electric generator housed in the rear section 213 and an eventual interconnection shaft configured to move the front coaxial rotor 250.

[0117] As seen in FIG. 24 and in transparency in FIG. 25, the axle fairing 246 is nothing more than a non-rotating casing comprising an elongated conical portion, which is coaxially positioned upstream of the front fan, and a radially flattened cylindrical portion symmetrically tapered at the leading and trailing edges, which forms a substantially horizontal bridge in connection with a radially inner annular face of the turbofan engine nacelle 240. The output shaft 244 is provided with a bearing (not shown) intended to support an output shaft support 244a, in the form of a crosshead configured to support the conical portion of the axle fairing 246, while the drive shaft 245 is supported by a bearing 245b of the axle fairing 246, which flattened cylindrical portion is integral with said inner surface of the turbofan engine nacelle 240, which in FIG.25 is seen being pierced by the drive shaft 245 housed in the flattened cylindrical portion of the axle fairing 246.

[0118] In a preferred embodiment, a thrust vector control nozzle for turbine engines is disclosed, comprising a segmented tubular body manufactured in dimensions and materials resistant to the high pressure and high temperatures of the exhaust gases of a turbofan engine. Shaped to be curved within a vertical plane downstream of a propeller nozzle, such an articulated duct is configured to direct engine thrust from a vertical lift position, through intermediate positions, to a propulsion position in which the generated thrust follows a path parallel to the axis of symmetry of an aircraft.

[0119] Designed to be wound or unwound around its own axis by an actuator, this articulated tubular device is integrated from the interconnection of a plurality of segments obtained from radial sections of a toroidal tube (or truncated tubular torus) with 90-degree curvature or % of a full tubular torus, the torus segments being joined by hinges centered along the back of the assembly, such as a spine. A first torus segment and two twin flat side plates, which have the general shape of one or two quadrants, are integrated into a single body, which in turn is integrated with a pair of swivel supports supported on bearings on a transverse shaft below the lower edge of the propeller nozzle.The actuator is configured to: i) unwind the hinged nozzle into a cowling over the engine, in a nozzle position that does not interfere with the horizontal direction of thrust generated by the engine; ii) roll up to fully contract the hinged nozzle into a bend downstream of the engine exhaust, in a nozzle position in which thrust is deflected vertically downward; and iii) partially roll up or unroll the hinged nozzle to obliquely deflect engine thrust as required for transition or conversion flight.

[0120] FIGS. 26-28 illustrate turbofan engine 240 provided with a preferred embodiment of such a thrust vectoring control nozzle, hereinafter referred to as “vectoring nozzle 10.” Through a nozzle fairing 11 illustrated in transparency, vectoring nozzle 10 is seen in FIG. 26 fully unfurled over turbofan engine 240 in a nozzle position suitable for straight-ahead propulsion (no diversion of thrust from the engine's propeller nozzle), the position of vectoring nozzle 10 being in which thrust generated by turbofan engine 240 follows a course parallel to the axis of symmetry of a fuselage.

[0121] Configured to house the vectoring nozzle 10 when unrolled, the nozzle fairing 11 also houses a hydraulic actuator 16. The figures show a pair of twin side plates 13 integral with a first nozzle segment 12 or torus segment, a plurality of nozzle segments 12 not integral with the side plates 13, plus hinges 14 and a pair of pulleys side plates 15, which are supported on bearings (not shown) and integral with the twin side plates 13 of the vectoring nozzle 10.

[0122] As illustrated in FIG. 27, the vectoring nozzle 10 is seen fully rolled up by a telescopic rod 16a of the hydraulic actuator 16 in a position in which the vertical thrust diverted downward from an exhaust nozzle of the turbofan engine 240 is adequate for the aircraft to hover, climb, or descend vertically. In FIG. 28, the same vectoring nozzle 10 is partially outside the nozzle fairing 11, in a position intermediate between fully rolled up and fully unrolled, indicating that the aircraft is flying in transition or conversion.

[0123] FIGS. 29-30 show an example embodiment of a thrust reverser for turbine engines, hereinafter referred to as "thrust reverser 20." It should be noted that a thrust reverser according to the invention is nothing more than a thrust vector control nozzle with twice the tubular height, i.e., twice the number of segments, of a thrust vector control nozzle and that, therefore, instead of deflecting the exhaust thrust of a turbine engine in an angular range of zero to 90 degrees from the horizontal, it can deflect it in a range of zero to 180 degrees to reverse the direction of the thrust generated by the engine during a landing on a runway like an airplane.

[0124] An actuator 26 manipulates the direction of thrust generated by turbofan engine 240 by rotating a screw shaft 27 engaged with a ball nut (not shown) of a housing 28, in turn connected by a rod 28a to a last thrust reverser segment 22, as in the enlarged view in FIG. 29. By moving housing 28 along screw shaft 27, actuator 26 winds or unwinds thrust reverser 20 about a side pulley shaft 25 to control the direction of thrust generated by turbofan engine 240 according to the operational requirements of an aircraft, as in the deceleration reverse thrust of FIG. 30, where thrust reverser 20 is seen wound out of a fairing 21.

Claims

CLAIMS 1. A convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, characterized in that it comprises a fuselage (110) comprising: a mid-section (112) to which a fixed wing system (120) is symmetrically coupled;a forward section (111) having a nose and a rear section (113) having a tail assembly provided with an empennage (130) comprising aerodynamic stabilizers provided with movable directional control surfaces, the forward section (111) and the rear section (113) being provided with respective forward and rear vertical lift units comprising: front and rear rotor supports (115) configured to operationally support the front and rear rotors (150) rotating synchronously in opposite directions, each rotor (150) being provided with a rotor hub (154) comprising: a rotor mast (151, 152) substantially vertical with respect to the attitude corresponding to level flight, the rotor mast (151, 152) being provided with a rotor brake unit controlling the rotational speed of the rotor hub; (154) until stopping it in a predefined position in transition flight to airplane mode; a pair of handles (155) integrated with cylindrical hinges (155a) provided on opposite symmetrical sides of the rotor hub (154), the handles (155) being elongated to hold rotor blades (156, 157), the cross-section of which is compatible with longitudinal cavities formed in the respective handles (155) where the rotor blades (156, 157) fit sandwiched between bearings; an actuator configured to longitudinally move the rotor blades (156, 157) sandwiched between bearings until they are centered and locked in their respective handles (155) in transition flight to airplane mode or until their roots are housed and locked in the same handles (155) in conversion flight to helicopter mode; a collective pitch control mechanism (158) in which an actuator tilts the handles (155) by rotating them about cylindrical hinges (155a); an edge conversion system configured to alternately interchange leading edges (157a, 157g) with trailing edges (157b, 157h) of the convertible rotor blades (157) in airplane mode transition flight or helicopter mode conversion flight;at least one fan (116), electric or driven in rotation by mechanical energy, symmetrically embedded in the tail section (113) to provide yaw control in helicopter mode and good aerodynamic properties in airplane mode after deactivation in transition flight; a rotational power source comprising at least one internal combustion engine, at least one electric motor, or at least one of each, with output shafts engaged with transmission and coupling mechanisms that power the front and rear rotors (150) or disengage from them; and at least one propulsion means configured to produce a propulsive force acting on the fuselage (110) in a direction parallel to the axis of symmetry.; 2. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the The fuselage (110) comprises a longitudinal roof portion projecting upwards with respect to the attitude corresponding to level flight, which is referred to as the angled longitudinal apex (114), extends along the axis of symmetry along the fuselage (110) and is intended to improve the flow of the air flow diverted by the rotor blades (156, 157) that impacts on the fuselage (110) in helicopter mode.

3. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the fixed wing (120) is a high wing.

4. The convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 3, characterized in that the high wing (120) is a gull wing.

5. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the aerodynamic stabilizers comprise a symmetrically centered horizontal stabilizer (131), the lateral ends of which are extended in the form of two inclined stabilizers (132) such as two laterally downwardly inclined flat surfaces provided with inclined rudders (134).

6. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the rear rotor support (115) is symmetrically embedded in the rear section (113), while the front rotor support (115) comprises support elements such as vertical pylons (115a) and horizontal beams (115b, 115c) with respect to the attitude corresponding to level flight, the pylons (115a) being symmetrically integrated to the forward section (111) and locked by a first beam (115b), which is locked to a roof portion over a cockpit by a second beam (115c).

7. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claims 1 and 6, characterized in that the rotation planes of the front and rear rotors (150) are separated by at least the length of a wing root chord.

8. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the front and rear rotor masts (151, 152) alternately tilt to the sides of the fuselage (110) assisted by elastic elements (151 e, 152e).

9. The convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the front and rear rotor masts are fixed relative to the front and rear rotor mounts (115) that support them.

10. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the actuator that moves the rotor blades (156, 157) longitudinally through the grips (155) comprises sets of electromagnets arranged both in the grips (155) and in the rotor blades (156, 157).

11. The convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the actuator that moves the rotor blades (156, 157) longitudinally via the handles (155) is electromechanical.

12. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the collective pitch control mechanism (158) comprises a concentric yoke (158a) of three rods, two counter-positioned toothed side rods being engaged with corresponding toothed rings of the cylindrical hinges (155a) and a telescopic central rod driven by said actuator.

13. The convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the blade edge conversion system comprises a controller, a magnetic actuator and the convertible rotor blade (157), which comprises: a spar box-type support member (157c), the cross-section of which is that of a longitudinally hollow symmetrical chassis, such as a flattened rhombus or a geometric figure with two inclined upper and two lower flat longitudinal faces, the spar box (157c) being the length of the convertible rotor blade (157); a longitudinally inner section (157j) having the same constitution and cross-section as a rotor blade of a conventionally designed helicopter and being as long as a handle (155);two twin convertible longitudinally outer sections (157k), each section measuring half the difference in length of a longitudinally inner section (157j) to the length of a whole blade, the four inclined plane faces of the spar box (157c) of the sections; longitudinally external sections (157k) being magnetized and each longitudinally external section (157k) comprising: a first upper skin or skin (157d) of flexible magnetized sheet detached from the stringer box (157c) and joined at the sides with a second lower skin or skin (157e) as long as both the upper skin (157d) and the longitudinally external section (157k), the upper skin (157d) being wider than the total width of the upper inclined faces; and said lower skin (157e) of rigid magnetized sheet being wider than the total width of the lower inclined faces of the stringer box (157c), the lower skin (157e) being cantilevered by a longitudinal hinge (157f) about the axis of symmetry at the boundary of the lower inclined faces.

14. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the blade edge conversion system comprises a controller, an electromechanical actuator (157q) and the convertible rotor blade (157), which comprises: a spar box-type support member (157i), the cross-section of which is that of a longitudinally symmetrical hollow chassis, such as a quadrilateral in which the upper side is curved and the lower side is straight or nearly straight, the spar box (157i) being the length of the convertible rotor blade (157); a longitudinally inner section (157j) having the same constitution and cross-section as a rotor blade of a conventionally designed helicopter and being as long as a handle (155);two twin convertible longitudinally outboard sections (157k), each section measuring half the difference in length of one section; longitudinally internal (157j) for the length of an entire blade and comprising: a pair of lateral support elements (1571) of cross-section in the general shape of a right triangle and as long as a longitudinally external section (157k), the lateral support elements (1571) being attached to or integral with the sides of the stringer box (157i) of each longitudinally external section (157k); an upper skin (157m) and a lower skin (157p), both adhered to the stringer box (157i) and as long as a longitudinally external section (157k), the lower skin being wider than the upper skin to cover the lateral support elements (1571);a pair of twin appendages (157n) of upper skin (157m) or plates of the same thickness and length as the upper skin (157m), the twin appendages (157n) hanging attached by elastic hinges to the upper vertices of each symmetrical side of the stringer box (157i) of each longitudinally outer section (157k) and serving to maintain the flow over the trailing edge (157h) in laminar regime; and a pair of twin rotating appendages as long as a longitudinally outer section (157k), the elongated cross-section of which illustrates the leading edge (157g) as rounded and the trailing edge (157h) as tapered, the twin rotating appendages being attached to opposite symmetrical sides of the lateral support members (157l) and configured to be rotated by the actuator (157q) about the own axes of the rounded edges or leading edges (157g).; 15. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the rotor blades (156) of both the front rotor (150) and the rear rotor (150) are provided with fixed or immovable leading edges and trailing edges.

16. The convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the internal combustion engine is a turbine engine (140).

17. Convertible aircraft (100) with tandem rotors (150) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 1, characterized in that the rotational energy source that drives the front and rear rotors (150) and the propulsion means are electric.

18. A convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, characterized in that it comprises a fuselage (210) comprising: a mid-section (212) to which a fixed wing system (220) is symmetrically coupled; a forward section (211) having a nose and a rear section (213) having a tail assembly provided with an empennage (230) comprising aerodynamic stabilizers provided with movable directional control surfaces, the forward section (211) and the rear section (213) being provided with respective forward and rear vertical lift units comprising: front and rear rotor supports (215) configured to operationally support the front and rear coaxial rotors (250), each coaxial rotor (250) being provided with two counter-rotating rotor hubs (254) comprising: substantially vertical concentric rotor masts with respect to the attitude corresponding to level flight, an inner mast (251) and an outer mast (253) being provided with rotor brake units, which control the rotation speed of the rotor hubs (254) until stopping them in a predefined position in transition flight to airplane mode; a pair of handles (255) integrated with cylindrical hinges (255a) provided on opposite symmetrical sides of each rotor hub (254), the handles (255) being elongated to hold rotor blades (256, 257), the cross-section of which is compatible with longitudinal cavities formed in the respective handles (255) where the rotor blades (256, 257) fit sandwiched between bearings;actuators configured to longitudinally move rotor blades (256, 257) sandwiched between bearings until they are centered and locked in their respective grips (255) in airplane mode transition flight or until their roots are housed and locked in the same grips (255) in helicopter mode conversion flight; collective pitch control mechanisms (258, 259) in which actuators tilt the grips (255) by rotating them about cylindrical hinges (255a); an edge conversion system configured to alternately interchange leading edges (257a, 257g) with trailing edges (257b, 257h) of the convertible rotor blades (257) in airplane mode transition flight or helicopter mode conversion flight;at least one fan (216), electric or driven in rotation by mechanical energy, symmetrically embedded in the rear section (213) to provide yaw control in helicopter mode and good aerodynamic properties in airplane mode after being deactivated in transition flight; at least one rotational power source comprising at least one internal combustion engine, at least one electric motor, or at least one of each, with output shafts (244, 245) engaged with transmission and coupling mechanisms that power the front and rear coaxial rotors (250) or disengage therefrom; and at least one propulsion means configured to produce a propulsive force acting on the fuselage (210) in a direction parallel to the axis of symmetry.

19. The convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 18, characterized in that the forward rotor support (215) comprises a single-piece column symmetrically integrated from the nose to a first roof portion of the fuselage (210).

20. The convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 18, characterized in that each front and rear coaxial rotor (250) comprises two rotor blades (256, 257) configured to be stopped, centered and locked in their respective grips (255) in transition flight to airplane mode, while another two rotor blades (256) are parked on the fuselage (210).

21. The convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 18, characterized in that the collective pitch control mechanisms (258, 259) comprise an upper rotor hub (254) integrated with the inner mast (251) and a lower rotor hub (254) integrated with the outer mast (253), the inner mast (251) being provided with a first concentric yoke (258a) comprising a telescopic central rod connected with a first actuator and two toothed lateral rods. counter-positioned gears meshed with corresponding toothed rings of the cylindrical hinges (255a); the outer mast (253) being provided with a second concentric yoke (259a) comprising two twin rings joined by rolling bodies, a stationary lower ring (259c) being provided with telescopic side rods (259d) connected with a second actuator and a rotatable upper ring (259b) provided with two counter-positioned toothed side rods meshed with corresponding toothed rings of the cylindrical hinges (255a).

22. The convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 18, characterized in that the internal combustion engine is a turbofan engine (240).

23. Convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 22, characterized in that a drive shaft of a front fan or turbofan engine fan (240) powers an output shaft (244) meshed with a transmission shaft (245), both housed upstream of the front fan in a stationary fairing (246) comprising a longitudinally elongated conical portion forward of the front fan being configured to support the output shaft (244), and an aerodynamically tapered portion extending in a direction perpendicular to the conical portion being configured to support the transmission shaft (245).

24. The convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 23, characterized in that the output shaft (244) and the transmission shaft (245) are positioned downstream of the front fan of the turbofan engine (240).

25. Convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to flight Helicopter engine according to claim 22, characterized in that the turbofan engine (240) is provided with a nacelle, an exhaust nozzle and a thrust vector control system comprising an articulated duct referred to as a vectoring nozzle (10) or thrust reverser (20), which is configured from the interconnection of a plurality of nozzle segments (12) or reverser segments (22) obtained from the radial sectioning of a toroidal tube and joined together by symmetrically centered hinges (14, 24), a first nozzle segment (12) or reverser segment (22) being integrated with a pair of twin side plates (13, 23), in the form of one or two quadrants integrated with twin side pulleys (15, 25) of a central or two lateral shaft, which are symmetrically integrated with a lower outer edge of the exhaust nozzle just below the exhaust of the turbofan engine (240),and a last nozzle segment (12) or thrust reverser segment (22) connected to an actuator (16, 26) by a rod (16a, 28a) intended to manipulate the vectoring nozzle (10) or thrust reverser (20) at any bending angle, from fully unrolled and extended within a fairing (11, 21) symmetrically arranged on the nacelle, to fully rolled around its own axis, outside the fairing (11, 21) and within a vertical plane with respect to the attitude corresponding to level flight downstream of the exhaust nozzle., 26. Convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 25, characterized in that the rod (16a) is a telescopic rod.

27. Convertible aircraft (200) with tandem rotors (250) that are stopped in transition flight to airplane mode and restarted in conversion back to helicopter flight, according to claim 25, characterized in that the rod (28a) is connected with a housing (28) provided with a ball nut engaged with a screw shaft (27), which is driven into rotation by the actuator (26).

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