US 6,607,161 B1Granted

Convertible aircraft with tilting rotors

AssigneeEurocopter

InventorsTomasz Krysinski, Rogelio Ferrer, Thomas Manfredotti, Eric Magre, Jean-Marc Klein

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Abstract

Improving convertible aircraft of the aforementioned type mainly in terms of the active control of vibrations, while at the same time avoiding the addition of significant additional masses for essentially countering the excitations caused by the rotors and, secondarily, of making such an aircraft easier to control in terms of roll in airplane mode. In this secondary objective, these improvements aim to allow simplifications to the maneuvering and command means for controlling the aircraft in terms of roll in airplane mode and preferably, at the same time, a simplification of the command and maneuvering means performing the functions of augmenting lift and reducing offsetting power. The invention also relates to improvements made to the convertible aircraft of the aforementioned type to give them the ability to land in airplane mode (without converting beforehand from airplane configuration to helicopter configuration). This possibility makes it possible to reduce the critical nature of the rotor tilt mechanisms in that landing remains possible without damage to the aircraft, whatever the position of the rotors. Furthermore, if both engines fail in airplane mode it is advantageous, particularly from the safety point of view, to be able to make a descent in airplane mode and in gliding flight and to land without having to tilt the rotors into helicopter mode before setting down, hence reducing the workload on the crew.

Claims20

Dependent claims

A method for the active control of the vibrations of a convertible tilt-rotor aircraft which can travel in airplane mode and in helicopter mode, and comprising at least one fuselage, at least one empennage with at least one stabilizer, a fixed wing structure comprising at least two wings extending laterally on each side of said fuselage and, in helicopter mode, a rotary wing structure comprising at least two rotors, each of which is supported and driven in rotation by a respective one of two drive nacelles each supported by a respective one of the two fixed wings extending from the fuselage as far as the corresponding nacelle, each rotor being mounted so that it can tilt with at least one front part, which supports said rotor, of the corresponding nacelle on the corresponding fixed wing and about an axis of tilt which is substantially transversal with respect to the fuselage, so as to switch between helicopter mode and airplane mode, in which mode the rotors act as propellers, each fixed wing being extended, substantially in the direction of its span and toward the outboard side of the corresponding nacelle with respect to the fuselage, by at least one outboard wing portion, at least part, of which pivots, independently of the rotor and of at least the front part of the corresponding nacelle, about an axis of articulation substantially transversal to the aircraft and constitutes an orientable surface which is at least one of a command surface and a control surface, whose pivotings about the axis of articulation are commanded, by at least one driven actuator, the method comprising the step of commanding the pivotings of said orientable surface at least at a frequency of the order of KbΩ, where b and Ω are, respectively, the number of blades and the frequency of rotation of each rotor, and K is a whole number at least equal to 1, so as to at least attenuate, at the fuselage, the fixed wings and the empennage and stabilizer, at least the vibrations generated naturally by the rotation of each rotor.

A convertible tilt-rotor aircraft which can travel in airplane mode and in helicopter mode, and comprising at least one fuselage, at least one empennage with at least one stabilizer, a fixed wing structure comprising at least two wings extending laterally on each side of said fuselage and, in helicopter mode, a rotary wing structure comprising at least two rotors, each of which is supported and driven in rotation by a respective one of two drive nacelles each supported by a respective one of the two fixed wings extending from the fuselage as far as the corresponding nacelle, each rotor being mounted so that it can tilt with at least one front part, which supports said rotor, of the corresponding nacelle on the corresponding fixed wing and about an axis of tilt which is substantially transversal with respect to the fuselage, so as to switch between helicopter mode and airplane mode, in which mode the rotors act as propellers, each fixed wing being extended, substantially in the direction of its span and toward the outboard side of the corresponding nacelle with respect to the fuselage, by at least one outboard wing portion, at least part of which pivots, independently of the rotor and of at least the front part of the corresponding nacelle, about an axis of articulation substantially transversal to the aircraft and constitutes an orientable surface which is at least one of a command surface and a control surface, whose pivotings about the axis of articulation are commanded, by at least one driven actuator, the convertible aircraft comprising a self-driven active anti-vibration system with at least one active vibration control computer commanding said at least one driven actuator causing said orientable surface to pivot about said axis of articulation at least at a frequency of the order of KbΩ, where b and Ω are, respectively, the number of blades and the frequency of rotation of each rotor, and K is a whole number at least equal to 1, so as to at least attenuate, at the fuselage, the fixed wings and the empennage and stabilizer, at least the vibrations generated naturally by the rotation of each rotor.

Dependencies are inferred from the claim text.