FR3078681A1 - METHOD FOR PUTTING A POWER DEFICIT IN THE EVENT OF AN ENGINE FAILING ON A MULTI-ENGINE ROTARY WING AIRCRAFT - Google Patents

Abstract

The present invention relates to an aircraft (1) having at least one rotary wing (3) which requires mechanical power supplied by a power plant comprising at least two motors (16). The at least two motors (16) are controlled by at least one computer (50) to be able to operate under a temporary emergency regime that can be used continuously for a limited time and a predetermined number of times only when one of the at least two motors (16) is down. The aircraft (1) comprises at least one rocket booster (20) controlled at least by said at least one computer (50), said at least one computer (50) being configured to require the ignition of a said booster rocket (20) when said at least one computer (50) controls the implementation of said temporary emergency regime on one of said at least two engines (16).

Description

Method for overcoming a power deficit in the event of an engine failure on a multi-engine rotary wing aircraft

The present invention relates to a method for overcoming a power deficit in the event of an engine failure on a multi-engine rotary wing aircraft, and a multi-engine rotary wing aircraft.

An aircraft may comprise a rotary wing as well as an anti-torque device for controlling the yaw movement of this aircraft. For example, a helicopter may include a main rotor participating in its lift and its propulsion as well as an anti-torque device for yaw movement control, such as a rear rotor or NOTAR® type. A hybrid aircraft can comprise a rotary wing and an anti-torque yaw movement control device which comprises, for example, at least one propellant or towing propeller.

The aircraft may also include a back-up device operating in the event of a breakdown of the yaw movement anti-torque device.

In particular, document US 7032860 describes a system provided with a propellant. This thruster is powered by a fuel tank to perform an anti-torque function in the event of a fault with a main anti-torque device.

Document EP1787907 describes the use of a solid fuel engine for this purpose.

Document US 2009/0101753 describes an emergency system comprising a pressurized gas tank. This tank is connected to an outlet nozzle by a valve.

Furthermore, a rotary wing aircraft comprises a power plant setting in motion the rotary wing and the anti-torque device for yaw movement control. The yaw movement anti-torque device may require significant power to be deducted from the power delivered by the power plant, at least during certain flight phases. On a helicopter, a tail rotor may require significant power delivered by the power plant during the hover and high speed flight phases.

According to another aspect, the power plant can comprise several motors.

The thermal limitations of the motors or even the torque limits of power transmission boxes allow normal engine operating regimes to be defined. These normal diets include for example:

- a take-off regime, usable for five to ten minutes, during which each engine can provide maximum take-off power PMD,

- a maximum continuous speed which can be used without restriction of time during which each engine can supply a maximum continuous power PMC less than the maximum take-off power PMD,

- maximum speed in transient operation usable for a limited time during which each engine can provide maximum power in transient PMT operation greater than the maximum take-off power PMD.

On a multi-engine aircraft, there are also emergency boost systems that are used in the event of an engine failure. These emergency overpower regimes may include:

- a continuous emergency regime which can sometimes be used for thirty minutes or without time restriction during which each engine in operation can provide continuous emergency power to OEICONT,

- a maximum emergency mode that can sometimes be used for thirty consecutive seconds at most, and three times during a flight, each engine in operation being able to provide a maximum emergency power OEI30 ”greater than the continuous emergency power OEICONT during this regime maximum emergency;

- an intermediate emergency mode which can sometimes be used for approximately two minutes after the maximum emergency power OEI30 ”or two minutes thirty seconds consecutively, each engine in operation being able to provide an intermediate emergency power OEI2 'greater than the emergency power continuous OEICONT and less than the maximum emergency power OEI30 ”.

The emergency powers to be provided to achieve the performance required in the event of an engine failure are then used to size the aircraft. Engines can in particular be oversized to be able to supply the required powers to the rotary wing in the event of an engine failure. Such oversizing can be penalizing in terms of mass.

The document US8683933 does not belong to the technical field of the invention relating to a solid fuel engine used to brake a vehicle.

Likewise, document US4676457 is far from the invention relating to a landing system which is provided with rockets.

The invention aims in this context to equip an aircraft fitted with an engine which rotates a rotary wing of at least one rocket propellant. The rocket propellant can be ignited to improve the performance of the aircraft.

The present invention relates in particular to a method for overcoming a power deficit in the event of an engine failure on a multi-engine rotary wing aircraft.

The invention thus relates to an aircraft, this aircraft having at least one rotary wing and an anti-torque device for controlling yaw movement, said at least one rotary wing and said anti-torque device requiring mechanical power supplied by a power plant of the aircraft. , said power plant comprising at least two motors, said at least two motors being controlled by at least one computer which is configured to drive at least one of said at least two motors by applying a regime chosen from among a plurality of memorized regimes, said plurality of regimes comprising at least one normal regime which can be implemented when no engine has failed and a temporary emergency regime which can be used continuously for a limited time and a predetermined number of times and only when engine is faulty, said predetermined number being greater than or equal to two. This aircraft comprises at least one rocket propeller, said at least one rocket propeller or even each rocket propeller being positioned to exert a complementary thrust, said at least one rocket propeller being controlled at least by said at least one computer, said computer being configured to require ignition of a rocket propellant when said temporary emergency regime is used on a said engine.

For example, at least one computer can store the parameters relating to the normal and emergency regimes described above, and controls at least one engine to apply one of these regimes at all times. In particular, each computer can be configured to adjust a fuel metering device in order to achieve with the engine the power PMC, PMD, PMT, OEICONT, OEI2 ’, OEI30” required by the speed applied at a given time.

A rocket propellant is sometimes called a "rocket engine". A rocket propellant can be of the type known by the English expression "solid rocket engine" or the expression "solid propellant engine"

Thus, the aircraft comprises one or even rocket boosters each exerting a thrust qualified as complementary when they are switched on. Such a complementary thrust acts directly or indirectly on the yaw movement of the aircraft.

According to one example, the additional thrust is exerted on a fuselage of the aircraft, for example on a tail boom or a tailplane or a fin, to generate on this fuselage a force in order to counter the yaw torque induced by the wing rotating.

According to another example, the additional thrust is exerted on a blade of the rotary wing to participate in the rotation of this rotary wing in order to reduce the yaw torque induced by the rotation of the rotary wing by the power plant . At isopower developed by the anti-torque device, the aircraft's yaw movement is therefore modified.

Regardless of the embodiment, when an engine failure is detected, at least one computer may require the passage of an engine still in operation in a mode implementing a temporary emergency regime with limited duration of use. This temporary emergency regime may for example be the maximum emergency regime and / or the intermediate emergency regime described above. Such a computer can be an "engine computer" of a system known by the acronym FADEC and the English expression "Full Authority Digital Engine Control".

This aircraft then comprises one or even rocket boosters which are ignited on the order of an engine computer. Possibly, two rocket boosters are never ignited and in operation at the same time. Each rocket thruster may be ignited before, at the same time, or after the start of the use of a temporary emergency regime with limited use period when this temporary emergency regime is used.

When an engine failure is detected, a computer may require the ignition of a rocket thruster and then a modification of the engine operating regime to implement a temporary emergency regime, or may require at the same time the ignition of a rocket propellant and a modification of the engine operating regime to implement a temporary emergency regime, or else may require a modification of the engine operating regime to put in operates a temporary emergency regime and then the ignition of a rocket propellant. The engine speed can be modified by modifying the power developed by this engine, for example by modifying the flow of fuel transmitted to the engine with a fuel metering device.

For example, each time an engine operates at OEI30 ”maximum emergency speed, a single rocket propellant is fired.

The main purpose of rocket boosters is not to replace a faulty anti-torque device. Apart from specific breakdowns, the anti-torque device remains functional when the rocket boosters are fired. The main purpose of the rocket boosters is then to exert an additional thrust aimed at reducing the thrust to be generated with the anti-torque device. The expression "complementary thrust" is used voluntarily to indicate that a rocket thruster provides additional thrust, and not a thrust intended to replace the thrust generated by the anti-torque device.

The contribution of the additional thrust reduces the power necessary for the operation of the anti-torque device. A human or automatic pilot can then act on commands to reduce the power delivered to the anti-torque device in order to maintain a yawning position of the aircraft, possibly using gyroscopic sensors. With regard to the prior art, a greater part of the power delivered by the power plant can therefore be used for the rotary drive of the rotary wing. If an engine failure occurs during forward flight, a rocket propellant is fired when the emergency system is activated. The pilot can then reduce the power consumed by the aircraft by reducing its speed to a safe speed, or can maneuver its controls instantly to generate more lift with the rotary wing.

If an engine failure occurs in a phase close to hovering, the pilot can instantly request more lift from the main rotor.

In this context, the motors or even certain mechanical assemblies can be dimensioned to provide a lower power compared to the prior art during certain temporary emergency regimes since the rocket boosters minimize the power necessary for the operation of the anti-torque device when these temporary emergency schemes are used. Such sizing can tend to optimize the mass of the installation.

A rocket thruster is therefore not necessarily used to compensate for a failure of the anti-torque device, but so that a maximized part of the power developed by the power plant is called upon for the rotary wing drive.

Furthermore, the anti-torque device remaining active, a human or automatic pilot can always maneuver the aircraft by controlling this anti-torque device.

Such a system is particularly advantageous for rotorcraft whose anti-torque function requires significant power, for example of the order of 20% of the total power generated by the power plant except in the event of engine failure.

In addition, sharing control of the yaw movement between the anti-torque device and the rocket boosters can tend to secure the rocket propellant system. Indeed, in the event of inadvertent triggering of a rocket propeller, the additional thrust generated by this rocket propeller can be compensated by the anti-torque device.

According to another aspect, apart from an engine failure, it is possible to ignite the rocket boosters following a malfunction of the anti-torque device requiring an emergency landing, for example a stopping of an anti-torque rotor. It is also possible to ignite the rocket boosters to temporarily improve the performance of the aircraft, for example to perform an avoidance maneuver.

This aircraft may further include one or more of the following characteristics.

According to one aspect, the anti-torque device can be configured to be able to generate a predetermined nominal thrust, said additional thrust possibly being less than the nominal thrust.

The additional thrust can be limited to a power much lower than the nominal power developed by the anti-torque device to maintain good yaw handling of the aircraft regardless of the flight phase. In addition, on the ground, this characteristic can tend to allow the aircraft to be kept in a position of static equilibrium.

According to one aspect, the aircraft may include an arming device, said arming device being configured to prohibit the operation of said at least one rocket propellant as long as this arming device is not controlled by a human pilot or automatic.

By default, the arming device can prohibit the operation of all rocket boosters. When the arming device is operated, a computer then has the possibility of controlling the ignition of the rocket boosters.

In order to ensure safety, the arming device can be used to inhibit rocket boosters when the aircraft is on the ground with the engines stopped.

The arming device may include a member located as close as possible to the rocket boosters in order to limit the risks of interference, and / or the risks linked to static electricity which can create an inadvertent triggering of the rocket boosters.

For example, the arming device may include at least one button maneuverable by a pilot and controlling a system breaking on request a link between a rocket propellant and a computer, such as a switch or equivalent, if necessary.

According to one aspect, said at least one or even each fused propellant can be for single use and devoid of a regulation system.

When a rocket propellant is fired, a pilot has no additional thrust control action to perform. The pilot can on the other hand adjust a collective pitch control of the blades of the rotary wing to increase the lift generated by the rotary wing and / or can control the anti-torque device.

The absence of system regulation can make it possible not to disturb the avionics or autopilot systems.

According to one aspect, said at least one or even each fused propellant may comprise a tubular envelope, said tubular envelope extending from a closed end to an open end, said envelope containing a solid fuel surrounding a hollow channel, said at least one rocket propellant comprising an igniter connected by a link to said at least one computer.

Such a solid fuel can for example be propellant. A conventional igniter can also be used.

When the system is if necessary armed by an arming device and a temporary predetermined emergency regime is used, a computer controls the firing of a propellant by transmitting a signal to the dedicated igniter of this propellant -rocket.

This architecture can avoid the simultaneous firing of rocket boosters.

Optionally, the hollow channel has a geometry of the fynocil type.

This geometry can tend to obtain a regular complementary thrust over time.

Such geometry is illustrated at the following internet address: https://en.wikipedia.org/wiki/Solid- propellant_rocket # / media / Fi le: Fi no_ex.jpg

According to one aspect, the aircraft may comprise a tail, said at least one or even each rocket propellant being at least partially arranged in the tail, said at least one or even each rocket propellant comprising a gas ejection opening opposite an external environment located outside the aircraft.

The expression "said at least one or even each rocket propellant being at least partially arranged in the tail unit" means that a rocket propellant can for example be entirely arranged in a tail unit, can be entirely arranged in a tail unit empennage with the exception of a part of its nozzle, may be arranged in a tail unit of a closed end of this rocket propellant to a section located upstream of said opening, or may be arranged nowhere else but in the tail ...

The rocket boosters thus extend inside the tail box or even outside the tail, for example one next to the other. Thus, each rocket propeller is naturally directed at least transversely in the reference frame of the aircraft thus generating a complementary anti-torque thrust. In addition, this arrangement does not require an additional container which should be protected and streamlined.

According to another variant, a rocket thruster generates an additional thrust by being located at the end of a blade of the rotary wing. This position has the advantage of reducing the power to be supplied to the anti-torque device to counter the yaw torque induced by the rotary wing.

According to one aspect, the aircraft can comprise at least one emergency activation device maneuverable by a human pilot, said at least one emergency activation device being connected to at least one rocket propellant and being configured to control the ignition of this at least one rocket propellant.

In one aspect, the aircraft may include a number of rocket boosters at least equal to said predetermined number. For example, said predetermined number can be equal to three and said aircraft can comprise three identical rocket boosters.

Indeed, certain regulations require that you can trigger the OEI30 ”maximum emergency regime three times during a flight. On such an aircraft, three rocket boosters are then used for example, a rocket propeller being ignited each time a maximum emergency regime OEI30 "is activated.

According to one aspect, the anti-torque device can comprise at least one anti-torque rotor and / or a propellant or even tractive propeller and / or a blower ejecting a gas through a tail boom of the aircraft.

In one aspect, each rocket propellant can be removable to form optional equipment. For example, the aircraft can be equipped with this optional equipment only when the aircraft has to operate in an environment unfavorable to its performance.

The invention further relates to a method for overcoming a power deficit in the event of an engine failure on a rotary wing aircraft according to this invention. This process includes the steps of:

- detection of a failure of one of said at least two motors,

- Activation by said at least one computer of the temporary emergency regime and activation by said at least one computer of a said rocket-thruster which exerts a complementary thrust.

According to one aspect, the method may include a step of arming said at least one rocket propellant, said at least one rocket propellant being inhibited before said arming step.

According to one aspect, the anti-torque device can be configured to be able to generate a predetermined nominal thrust, said additional thrust being less than the nominal thrust.

The invention and its advantages will appear in more detail in the context of the description which follows with examples given by way of illustration with reference to the appended figures which represent:

- Figures 1 to 3, diagrams showing aircraft according to the invention,

FIG. 4, a diagram illustrating rocket boosters in a tailplane,

- Figure 5, a diagram illustrating a rocket propellant,

FIG. 6, a diagram illustrating a rocket thruster provided with a fynocil type channel, and

- Figure 7, a diagram illustrating the method according to the invention.

Figures 1 to 3 show various aircraft 1 each provided with an assistance system 200 according to the invention.

Regardless of the nature of the aircraft and with reference to FIG. 1, an aircraft 1 according to the invention comprises a fuselage 2 and at least one rotary wing 3. This rotary wing 3 comprises a plurality of blades 4 which participate at least in the lift of the aircraft 1 or even to the propulsion of the aircraft 1. The rotary wing 3 can be carried by a support structure of the aircraft 1, and can be arranged above the fuselage 2.

This rotary wing 3 is rotated by a multi-engine power plant 15, for example of a conventional type. This power plant 15 has at least two motors 16, for example turboshaft engines and / or piston engines and / or electric motors ... The motors 16 rotate the rotary wing directly or via a mechanical chain. Such a mechanical chain can comprise at least one main power transmission box 17, at least one transmission shaft, at least one coupling device, at least one freewheel or equivalent ... For example, the motors 16 put in movement of a main power transmission box 17 via at least one drive shaft and / or a freewheel, the main power transmission box 17 rotating the rotary wing via a rotor mast.

Furthermore, the engines are controlled by at least one engine computer more simply called "computer 50", for example a computer of a system of the type

FADEC.

Optionally, each engine is controlled by its own computer 50, the computers 50 communicating with one another.

Each computer 50 may for example include at least one processor, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression "computer". Each computer can communicate or include various sensors measuring engine parameters, such as torque, temperature, rotation speed, position sensors, etc.

Each computer can control at least one engine so as to respect an operating regime. Optionally, a computer stores the parameters of several regimes, and drives an engine to follow one of these regimes, on the order of a human pilot or an autopilot for example. These regimes can include at least one normal regime which can be implemented when no engine is broken down as well as at least one emergency regime. Said at least one emergency regime can comprise at least one temporary emergency regime which can be used continuously for a limited time as well as a predetermined number of times and only when one of the motors 16 is out of order.

Thus, a computer can for example apply one of the normal regimes described above developing the powers PMC, PMD, PMT respectively. By way of illustration, each computer controls at least one engine to operate according to the take-off regime for take-off of the aircraft, then according to the maximum continuous regime or even according to the maximum regime in transient operation if necessary during specific flight phases. If a computer reports an engine failure making it unusable, the remaining engines in operation can be controlled by at least one computer to apply one of the emergency regimes. By way of illustration, each computer controls at least one engine to operate according to the continuous emergency regime or even according to a temporary emergency regime which includes the maximum emergency regime and / or the intermediate emergency regime if necessary during phases specific flight.

In this context and independently of the implementation of the power plant 15, the rotation of the blades 4 of the rotary airfoil under the action of motors 16 via a mechanical chain induces the creation of a torque in yaw on the fuselage of the aircraft 1.

Consequently, the aircraft comprises an anti-torque device 10 for controlling yaw movement, and in particular an anti-torque device 10 motorized by the power plant enabling a human or automatic pilot to control the yaw movement of the aircraft. The aircraft may also include a tailplane 6. The aircraft may also include a fin which participates in controlling the yaw movement, and which may be fitted with a flap.

According to another aspect, this anti-torque device 10 is configured to generate a predetermined nominal thrust. For example, the nominal thrust is around 80% to 90% of the maximum thrust that this anti-torque device 10 can exert.

According to Figure 1, the anti-torque device 10 comprises at least one propeller 11 carried by a wing. The propeller 11 is rotated by the motors 16, for example via the main power transmission box 17.

According to FIG. 2, the anti-torque device 10 comprises a "fan" 13 ejecting air via orifices 14 of a tail beam 5 of the fuselage 2. The fan 13 takes the form of a propeller rotated by the motors 16, for example via the main power transmission box 17.

According to FIG. 3, the anti-torque device 10 comprises a rear rotor 12 carried by a tail beam 5 of the fuselage 2. The rear rotor 12 is rotated by the motors 16, for example via the main power transmission box 17 and / or a rear power transmission 18.

Whatever the variant and by way of illustration with reference to FIG. 3, each rotary wing 3 and the anti-torque device 10 then each require a part of the mechanical power supplied by the power plant 15.

Furthermore, the aircraft 1 comprises at least one rocket propeller 20 to be ignited when a temporary emergency regime with a limited duration of use is activated.

Each rocket thruster can be for single use and without a regulation system. When a rocket propeller is ignited, it then exerts an additional thrust as long as the fuel contained in this rocket propellant is not consumed.

According to another aspect, the additional thrust exerted by a rocket propeller can be less than the nominal thrust exerted by the anti-torque device 10.

For example, the aircraft 1 comprises a number of rocket boosters which is at least equal or even strictly equal to the predetermined number of uses of the temporary emergency regime or of the temporary emergency regimes associated with the rocket boosters.

It is possibly possible to plan to ignite a rocket thruster during the implementation of each temporary emergency regime with a limited duration of use. When the engines can operate once under the maximum emergency regime OEI2 "and three times under the intermediate emergency regime OEI30" for example, the aircraft may include four rocket boosters.

It is possible to plan to ignite a rocket propellant during the implementation of each temporary emergency regime with a limited duration of use.

Alternatively, it is possibly possible to plan to ignite a rocket propellant only when using the limited-time emergency regime allowing the greatest power to be developed, ie the maximum emergency regime OEI30 ”according to the example. described. When the engines can operate once under the intermediate emergency regime OEI2 'and three times under the maximum emergency regime OEI30 ”, the aircraft may comprise three rocket boosters respectively ignited during the activation of the three uses of the regime maximum emergency OEI30 ”.

For example, a rocket thruster can be ignited when an OEI30 ”maximum emergency mode is activated. When the aircraft comprises a computer authorizing an engine to operate under the maximum emergency regime three times during the flight, the aircraft may then comprise three rocket boosters, a single rocket propeller being ignited each time the intermediate emergency regime is used.

In one aspect, each rocket propellant 20 is arranged in the aircraft so as to exert a complementary thrust having an effect on the yaw movement of the aircraft.

According to a variant, each rocket propeller is arranged on a blade 4 of the rotary wing.

According to FIG. 4, at least one rocket propellant 20 can be at least partially arranged in the tail unit 6. For example, each rocket propellant is at least contained in a box 64 of the tail unit 6. Such a box 64 can be delimited in a rope direction of the empennage by two longitudinal members 61, in a major direction of the empennage by at least one or even two ribs 62 and in a thickness direction by skins 63. An area 66, for example a rib, is further pierced so that each propellant has an opening 65 for ejecting gas opposite an external environment EXT. For example, a nozzle of a rocket propellant leads to the opening 65 or passes through an opening 65.

According to another aspect, a rocket propellant 20 can be of the type described in FIG. 5

Such a rocket propellant 20 then comprises a hollow tubular casing 21. This tubular envelope 21 extends along its length from a first end called "closed end 22" to an end called "open end 23". The first end is qualified as "closed end" because of the presence of a bottom 220 which closes this first end. Conversely, the second end is qualified as "open end" due to the presence of an access 230 to the external environment EXT.

The rocket propellant further comprises a solid fuel 24 which is contained in the envelope 21. This solid fuel 24 can be attached to a wall of the envelope.

Alternatively, this solid fuel may have a longitudinal cavity forming a hollow channel 25 which passes through this solid fuel. Consequently, the solid fuel surrounds the channel 25, this channel forming a combustion chamber. According to FIG. 5, this channel 25 can have a geometry of the fynocil type.

A rocket propellant devoid of such a channel is also possible depending on the level of power to be produced and / or the operating time to be reached.

Referring to Figure 5, the rocket propellant 20 may include a nozzle 35. This nozzle 35 may for example be provided with a convergent 351 arranged in the casing 21, optionally against the solid fuel 24, then a divergent 352 which extends at least partially into the external environment EXT. According to the example illustrated, a neck 353 of the nozzle 35 interposed between the convergent 351 and the divergent 352 is positioned substantially in the access 230.

Furthermore, the rocket propellant 20 may include a conventional igniter 30. For example, this igniter is arranged in the casing 21, between the bottom 220 and the solid fuel 24. This igniter can be connected by a link 40 to at least one computer 50. Such a link can comprise at least one wire, at the minus a switch ...

Indeed and in accordance with FIG. 7, each rocket propeller 20 can be controlled by at least one computer 50, each computer 50 being configured to require the ignition of a said rocket propeller 20 during the implementation of a regime temporary emergency with limited duration of use.

For example, each engine 50 computer is connected directly or indirectly by a link 40 to the igniter of each rocket propeller 20. Each link 40 illustrated has wires 41 and a switch 42.

Furthermore, the aircraft 1 may include an arming device 55. For example, the arming device 55 includes one or more buttons 56 connected to switches 42 of the connections 40. Otherwise, the switches are open which prevents ignition of the rocket boosters. By cons, when a pilot operates the button or buttons, the arming device 55 closes the switches by conventional means. Thus, the arming device is configured to prohibit the operation of the rocket boosters 20 as long as this arming device 55 is not controlled by a human or automatic pilot.

According to another aspect, the aircraft 1 may comprise at least one emergency activation device 70. For example, the emergency activation device 70 comprises several buttons 71 connected respectively to the igniters 30. The operation of a button 71 then causes the associated rocket propellant 20 to ignite.

Therefore, the invention also relates to a method for overcoming a power deficit in the event of an engine failure 16.

According to this method, a computer 50 can detect a failure of one of the motors 16, and for example a failure rendering this motor unusable. If necessary, this computer 50 or another computer 50 then controls at least one engine in operation to apply a temporary emergency regime with a limited duration of use. At the same time, or before or after, this computer sends a signal to an igniter 30 of a rocket propeller 20 which exerts a complementary thrust 5 before going off completely. This process can possibly be repeated several times, for example three times using three rocket boosters respectively when the aircraft limits the use of the temporary emergency regime to three times.

If necessary, this process is only authorized if the arming device 10 has been operated during an arming step.

Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to identify exhaustively all the possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims (13)

1. Aircraft (1), said aircraft (1) having at least one rotary wing (3) and an anti-torque device (10) for controlling yaw movement, said at least one rotary wing (3) and said anti-torque device (10 ) requiring mechanical power supplied by a power plant (15) of the aircraft, said power plant (15) comprising at least two motors (16), said at least two motors (16) being controlled by at least one computer (50 ) which is configured to drive at least one of said at least two engines by applying a speed chosen from a plurality of stored speeds, said plurality of speeds comprising at least one normal speed which can be implemented when no motor is broken down as well as a temporary emergency regime which can be used continuously for a limited time and a predetermined number of times and only when one of said at least two motors (16) has failed, said pred number determined being greater than or equal to two, characterized in that said aircraft (1) comprises at least one rocket propeller (20), said at least one rocket propeller (20) being positioned to exert a complementary thrust, said at least one rocket engine (20) being controlled at least by said at least one computer (50), said at least one computer (50) being configured to require ignition of said at least one rocket engine (20) when used of said temporary emergency regime on one of said at least two engines (16). 2. Aircraft according to claim 1, characterized in that said anti-torque device (10) being configured to be able to generate a predetermined nominal thrust, said complementary thrust is less than the nominal thrust. 3. Aircraft according to any one of claims 1 to 2, characterized in that said aircraft (1) comprises an arming device (55), said arming device (55) being configured to prohibit the operation of said at least a rocket thruster (20) as long as this arming device (55) is not controlled by a human or automatic pilot. 4. Aircraft according to any one of claims 1 to 3, characterized in that said at least one rocket propellant (20) is for single use and does not have a regulation system. 5. Aircraft according to any one of claims 1 to 4, characterized in that said at least one rocket propellant (20) comprises a tubular casing (21), said tubular casing (21) extending from a closed end (22) to an open end (23), said tubular casing (21) containing a solid fuel (24) surrounding a hollow channel (25), said at least one rocket propellant (20) comprising an igniter (30) connected by a link (40) to said at least one computer (50). 6. Aircraft according to claim 5, characterized in that said hollow channel (25) has a geometry of the fynocil type. 7. Aircraft according to any one of claims 1 to 6, characterized in that said aircraft (1) comprises a tail (6), said at least one rocket propellant (20) being at least partially arranged in the tail ( 6), said at least one rocket propellant (20) comprising an opening (65) for ejecting gas opposite an external environment (EXT) located outside the aircraft (1). 8. Aircraft according to any one of claims 1 to 7, characterized in that said aircraft (1) comprises at least one emergency activation device (70) maneuverable by a human pilot, said at least one activation device emergency (70) being connected to said at least one rocket propellant (20) and being configured to control the ignition of this at least one rocket propellant (20). 9. Aircraft according to any one of claims 1 to 8, characterized in that said aircraft comprises a number of rocket boosters (20) at least equal to said predetermined number. 10. Aircraft according to any one of claims 1 to 9, characterized in that said anti-torque device (10) comprises at least one anti-torque rotor (12) or a propeller (11) or a blower (13) ejecting a gas through a tail boom (5) of the aircraft (1). 11. Method for overcoming a power deficit in the event of an engine failure (16) on an aircraft (1) with rotary wing (3) according to any one of claims 1 to 10, characterized in that the method comprises the stages of: - detection of a failure of one of said at least two motors (16), - Activation by said at least one computer (50) of the temporary emergency regime and activation by said at least one computer (50) of a said rocket propellant (20) which exerts a complementary thrust. 5 12. The method of claim 11 characterized in that said method comprises a step of arming said at least one rocket propellant (20), said at least one rocket propellant (20) being inhibited before said arming step. 10 13. Method according to any one of claims 11 to 12, characterized in that said anti-torque device (10) being configured to be able to generate a predetermined nominal thrust, said additional thrust is less than the nominal thrust.