WO2009008012A1

WO2009008012A1 - Simplified helicopter drive system

Info

Publication number: WO2009008012A1
Application number: PCT/IT2007/000489
Authority: WO
Inventors: Gaetano Perugini
Original assignee: Aviointeriors S.P.A.
Priority date: 2007-07-06
Filing date: 2007-07-06
Publication date: 2009-01-15

Abstract

A helicopter drive system for controlling main rotor (10) collective pitch; main rotor cyclic pitch; throttle, and tail rotor pitch, comprising one single, all integrated control arrangement (1); comprising a main control column (2), said column being ratable about a forward and backward cyclic pitch control axis (f-f) and about a left and right cyclic pitch control axis (r-r); first throttle grip means (3d, 3s) associated to said main control column (2), ratable about a throttle control axis (t-t); second collective grip means (3d, 3s) associated to said main control column (2), rotable about a collective pitch control axis (1-1); the overall configuration being such that said all integrated control arrangement has at least four degrees of freedom (β, γ, δ, α) respectively for the control of main rotor collective pitch; main rotor fore and aft cyclic pitch; main rotor left and right cyclic pitch; throttle; and optionally said tail rotor pitch; and is operable by a pilot (50) by either or both of the hands as desired; said main control column (2) feeling the overall fore-aft and left-right movements imparted by said pilot (50) by operation on said first and second grips means (3s, 3d); the selective movement of said main control column (2) and/or of said grip means (3s, 3d) affecting respective output means apt to responsively provide said main rotor (10) and/or said throttle, and/or said tail rotor pitch, with a respective control command.

Description

SIMPLIFIED HELICOPTER DRIVE SYSTEM

SPECIFICATION

The present invention relates to a simplified helicopter drive system; as well as to a helicopter incorporating such a drive system.

This invention relates to the field of the manufacturing of integrated flight control systems, specifically conceived for helicopters but optionally adaptable to general means of transport. More particularly, this invention relates to a unified, optimized flight attitude control system comprising a single, multi-task all integrated flight control arrangement means, for simplified control of the main rotor collective pitch; of the main rotor cyclic pitch and of the throttle; and optionally also of the tail rotor pitch.

More specifically, the present invention concerns the production of helicopter drive systems which are operational through manoeuvre by the pilot of substantially one single command interface.

To date, the drive systems commonly issued on the means of transport, and typically on flying vehicles and more specifically on helicopters, generally require that the driver, and typically the pilot, be acquainted with a plurality of command interfaces.

To date, flying an helicopter requires that the pilot constantly hold his left hand on the collective pitch lever, whose handle incidentally also operates the throttle; that his right hand on the cyclic pitch stick; and that in the meantime his feet constantly control the tail rotor pitch by applying differential pressure on pedals. Consequently, potential new users may be put off by the above, well assessed but complicate driving technique, and may therefore feel reluctant to approach helicopter piloting due to the established, peculiar, asymmetrical and stressing driving procedure it implies.

Currently, helicopter driving requires the control of three basic flight attitude inputs, such as the collective pitch control; the cyclic pitch control and the antitorque control.

The collective pitch control is for the regulation of the lift exerted by the main rotor, and thus for the increase or decrease in altitude of the helicopter and for its vertical motion, by equally changing the pitch angle of all main rotor blades simultaneously, regardless of the blades' rotational position in the swing about the rotor head.

A collective lever is customarily located on the left side of the pilot's seat and is thus normally actuated by the pilot's left hand.

At the end of this collective lever is conventionally mounted a handgrip, normally a twist grip handle, which, when rotated by the pilot's hand, acts on the engine throttle and thus sets the desired engine power, typically adjusting it for compensation of a change in the collective pitch and maintenance of a constant number of revolutions per minute of the main rotor.

The cyclic pitch control substantially tilts the main rotor disc by cyclically changing the pitch of the rotor blades in their cycle of rotation.

The pitch of a given blade is thus different depending upon its instantaneous rotational position in the swing about the rotor head.

The result is the substantial tilting of the main rotor disk in a particular direction, the horizontal component of the differential lift thus developed by said main rotor moving the helicopter in the direction of tilt.

A vertical cyclic stick is usually located frontally between the pilot's legs, so as to be actuated by the pilot's right hand.

With respect to its neutral position, the stick can be moved forward and backward, left and right, in order to have the helicopter move in corresponding directions.

The direction in which the nose of a helicopter is pointed, otherwise adversely affected by the torque effect of the main rotor, is generally controlled by anti-torque pedals.

Such pedals are apt to adjust the vectorial value of the thrust produced by the tail rotor by determining a variation in the pitch angle of the tail rotor blades, so as to cause the nose of the helicopter to yaw in the desired direction as instructed by pedal manipulation.

Two anti-torque pedals are traditionally located on the cabin floor, so as to be actuated by the pilot's feet.

Driving a helicopter according to the state of the art therefore requires that the pilot constantly hold his left hand on the collective pitch lever, through whose handle the throttle is also operated; that he concomitantly keep his right hand on the cyclic pitch stick; while concurrently keeping his feet on the pedals for controlling the tail rotor pitch.

Owing to that, the resulting position of the pilot is asymmetrical and, if one hand leaves its assigned position, the abandoned control(s) cannot be operated by the other hand.

Even though the above scheme is universally accepted as the standard way to control a helicopter, it is most likely to be an obstacle, or even a deterrent, to potential new users, generally accustomed to driving car or to flying light airplanes which prove much simpler to be controlled than helicopters.

A remarkable limitation of the conventional actuation of helicopter controls lies in that it is not sufficiently user-friendly and fully instinctive and it besides constrains the pilot to an unnatural position, with all main limbs busy, which needs to be kept at any flight instant, least a control remains temporarily but dangerously vacant/unattended .

To date, there is not a simplified helicopter drive system providing the pilot with one compact, substantially single-lever, all integrated control arrangement, apt to effectively and completely control the helicopter by a fully instinctive actuation, such as to allow the adoption of a jointly straightforward, precise, versatile, relaxed and comfortable piloting technique.

Moreover, in the known art of the reference field, there is no drive system, either based on electro-mechanical kinematic schemes or fly-by-wire schemes, such as to attain a substantially symmetrical piloting position and wherein the whole of the controls can be equivalently operated by one hand only, allowing the pilot to optionally release one of his hand's hold from the controls and thus to divert it from actual manoeuvring.

Hence, object of the present invention is to solve said problems, by proposing a helicopter drive system for controlling main rotor collective pitch; main rotor cyclic pitch and throttle, and optionally tail rotor pitch, comprising one compact, substantially single-lever, all integrated control arrangement;, as well as a helicopter incorporating said drive system, as set forth in claim 1 and in claim 19, respectively.

The helicopter drive system according to the present invention proposes an innovative, fully instinctive control arrangement incorporating at least all of the main rotor controls, making helicopter piloting simpler, more user-friendly and thus more approachable, substantially similar to that of a car or of a light airplane.

Thanks to its versatility, the drive system according to the present invention may advantageously and inexpensively be fitted to any typology and configuration of means of transport, and particularly to any helicopter model on the market, for its installation entailing no carrying out of costly and complex modifications on the original structure of the means of transport.

Hence, the drive system according to the present invention is of easy installation and use, as well as of simple design and inexpensive production, being implementable in already produced helicopters with very little changes to the design project of existing plants and structures, since interfaces are not substantially altered. During cruising in steady condition, the pilot can advantageously relax, holding the handle bar by one hand only, either left or right thanks to suitable kinematics mirroring all movements from one handle to the other.

In a model with optionally integrated tail rotor pitch control, the pilot's feet area being freed from pedals, a better downward visual range is allowed.

The drive system according to the present invention therefore ensures enhanced safety for the pilot and occupants of the helicopter to which the system is applied, as well as advantageously favourable to an agile manoeuvring of said helicopter. The drive according to the present invention advantageously implements an effective all-in-one control interface.

Further advantages, as well as the features and the operation modes of the present invention will be made apparent in the following detailed description of two embodiments thereof, given by way of example and without limitative purposes, making reference to the figures of the annexed drawings, wherein:

Fig. 1 is a perspective view apt to schematically reproduce a helicopter drive system according the prior art;

- Figures from 2 to 5 are perspective views of the controls of the helicopter drive system of Fig. 1, apt to schematically display the activation modes thereof by a pilot of said helicopter;

- Figures 6 and 7 are schematic views apt to illustrate the manoeuvres resulting from the activation of the controls of the drive system of Fig. 1 respectively according to the modes of Fig. 3 and Fig. 5;

Figure 8 is a perspective view of an all-in-one, compact, integrated control arrangement of a helicopter drive system according the present invention;

- Figure 9 is a perspective view apt to schematically reproduce a helicopter drive system according to a first embodiment of the present invention;

- Figures from 10 to 13 are schematic representations of the controls of the all-in-one, compact, integrated control arrangement of Fig. 8, apt to schematically display four possible activation modes thereof by a pilot of said helicopter;

- Figure 14 is a perspective view apt to schematically reproduce a helicopter drive system according to a fly-by-wire variant of the first embodiment of the present invention reproduced in Fig. 9;

- Figure 15 is a perspective view apt to schematically reproduce a helicopter drive system according to a second embodiment of the present invention;

- Figure 16 is a schematic representation of the controls of the all-in-one, compact, integrated control arrangement of Fig. 8, apt to schematically display one further possible activation mode thereof by a pilot of said helicopter, according to the second embodiment of the present invention reproduced in Fig. 15;

Fig. 17 is a perspective view apt to schematically reproduce a helicopter drive system according to a fly-by-wire variant of the second embodiment of the present invention reproduced in Fig. 15; - Fig. 18 contains a frontal view, a side view and two respective cross section views A-A and B-B of the all-in-one, compact, integrated control arrangement of Fig. 8, apt to schematically display a possible mechanism for the implementation of the activation mode of Fig. 10; Fig. 19 contains a frontal view, a side view, two respective cross section views A-A and B-B, and one plan view of the all-in-one, compact, integrated control arrangement of Fig. 8, apt to schematically display a possible mechanism for the implementation of the activation mode of Fig. l i;

Fig. 20 contains a frontal view, a side view, two respective cross section views A-A and B-B, and one plan view of the all-in-one, compact, integrated control arrangement of Fig. 8, apt to schematically display a possible mechanism for the implementation of the activation mode of Fig.

13;

Fig. 21 contains a frontal view, a side view, two respective cross section views A-A and B-B, and one plan view of the all-in-one, compact, integrated control arrangement of Fig. 8, apt to schematically display a possible mechanism for the implementation of the activation mode of Fig.

12;

- Fig. 22 contains a frontal view, a side view, two respective cross section views A-A and B-B, and one plan view of the all-in-one, compact, integrated control arrangement of Fig. 8, apt to schematically display a possible mechanism for the implementation of the activation mode of Fig. 16, according to the second embodiment of the present invention reproduced in Fig. 15 ; - Fig. 23 is a schematic representation of the helicopter drive system according to an electrically-activated, fly-by-wire variant of the present invention, suitable to both the first embodiment of Fig. 14 and to the second embodiment of Fig. 17.

In order to describe a preferred embodiment of the present invention, hereinafter reference will be made to the above indicated figures.

The helicopter drive system according to the present invention is described hereinafter according to two embodiments thereof, and to respective electrically- actuated variants of said two embodiments.

Of course, the drive system according to the present invention could undergo modifications functional to the application to helicopters with features different with respect to those exhibited by the one hereinafter considered for simply illustrative and not for limitative purposes.

The helicopter drive system according to the present invention comprises one single, all integrated, multi-task flight control arrangement means 1 for simplified control of the main rotor 10 collective pitch; of the main rotor 10 cyclic pitch and of the throttle; and optionally also of the tail rotor 11 pitch. The single, all integrated, multi-task flight control arrangement means 1 according to the presente invention effectively replaces conventional command interfaces, and specifically replaces at least collective pitch lever 23 and cyclic pitch stick 24.

Such control arrangement means 1 comprises a main control column 2. The main column 2, preferably substantially pivotably floor mounted, is made ratable about a forward and backward cyclic pitch control axis f-f.

A rotation γ imparted by a pilot 50 on the main column 2 about said forward and backward cyclic pitch control axis f-f is such as to produce a proportional variation in the pitch attitude of the helicopter. The main column 2 is also made ratable about a left and right cyclic pitch control axis r-r.

A rotation δ imparted by a pilot 50 on the main column 2 about said left and right cyclic pitch control axis r-r is such as to produce a proportional variation in the roll attitude of the helicopter, and to have thus the helicopter move in the corresponding direction.

First throttle grip means 3d, 3s are associated to said main control column 2, and made ratable about a throttle control axis t-t.

A rotation α imparted by a pilot 50 on the first throttle grip means 3d, 3s about said throttle control axis t-t is such as to proportionally regulate the engine power, or load, and correspondingly determine a set number of rounds per minute of the main rotor 10

Second collective grip means 3d, 3s are associated to said main control column 2, and made ratable about a collective pitch control axis 1-1.

A clockwise or counter clockwise rotation β imparted by a pilot 50 on the second throttle grip means 3d, 3s about said collective pitch control axis 1-1 is such as to proportionally collectively regulate the angle of attack of the totality of the main rotor 10 blades and consequently the value of the lift force thereby generated.

Such a movement of the second throttle grip means 3d, 3s about said collective pitch control axis 1-1 is substantially instinctive, in that the collective pitch increases, and the lift concomitantly grows bringing about a proportional elevation in the helicopter altitude, when the grip means go up; and vice versa. The overall configuration is such that the all integrated control arrangement 1 has at least four degrees of freedom β, γ, δ, α, respectively for the control of main rotor collective pitch; main rotor fore and aft cyclic pitch; main rotor left and right cyclic pitch and throttle.

The integrated control arrangement 1 is operable by a pilot 50 by either or both of the hands as desired.

, The configuration is such that the main control column 2 feels the overall fore-aft and left-right movements imparted by the pilot 50 by operation on said first and/or second grips means 3s, 3d.

The first and second grip means preferably are concomitantly seizable handle levers 3s, 3d, having for instance a substantially cylindrical configuration.

The first throttle grip means 3d, 3s and/or the second throttle grip means 3d, 3 s are preferably linked by a mechanism which mirrors the movement of the corresponding seizable handle levers.

Therefore, if just one handle lever is rotated, then the other handle lever can automatically follow the same path.

The selective movement of the main control column 2 and/or of the grip means 3s, 3d affects respective output means apt to responsively provide the main rotor 10 and/or said engine throttle body with a respective control command.

Conventionally, said output means comprise a swashplate 70, both connected to the cyclic and the collective controls, translating the pilot's, or autopilot's, commands via the helicopter flight controls into motion of the main rotor 10 blades, respectively by tilting in all directions with respect to the main rotor 10 mast and by vertically moving along the mainshaft.

The one single, all integrated, multi-task flight control arrangement 1 is designed and mounted to the structure of the helicopter so as to be symmetrically disposed and symmetrically operable with respect to the driving position of the pilot 50. The driving position of the pilot 50 is therefore made highly ergonomic, assuring efficient, smooth, straight-forward execution of all driving maneuvers.

Such maneuvers can be thus advantageously executed in a combined mode, acting on the integrated, multi-task flight control arrangement 1 by applying thereto one only, comprehensive movement, so as to couple, for instance, the abovementioned rotations γ and δ respectively for the control of the pitch and roll attitude.

The first and second grip means 3s, 3d are preferably associated to said main control column 2 through an intermediate control head assembly 4, mounted on said main control column 2, preferably centrally on the upper end of said substantially floor mounted column.

The intermediate control head assembly 4 is preferably operable as a hand wheel.

According to a first embodiment of the present invention, a conventional antitorque pedal device 25 may be used for controlling the pitch, and therefore the vectorial thrust, of the tail rotor blades.

According to a second embodiment of the present invention, represented in Figures 15, 16, 17 and 22, the all integrated control arrangement 1 is also apt to control the tail rotor pitch, and thus the yaw attitude of the helicopter, preferably through said intermediate control head assembly 4.

To this avail, the intermediate control head assembly 4 is rotably mounted on the main control column 2 so as to be pivotable about a yaw control axis y-y.

A rotation ε, imparted by a pilot 50 on the intermediate control head assembly 4 about said yaw control axis y-y, is such as to produce a proportional variation in the yaw attitude of the helicopter, as it can be derived from Fig.16.

The intermediate control head assembly is operable on said control column 2 as a ratable hand wheel 4, the selective rotational movement ε of the hand wheel 4 with respect to said main control column 2 affecting respective output means apt to responsively provide the tail rotor 11 with a respective, proportional control command.

When the hand wheel 4 is rotated clockwise, the helicopter yaws clockwise; when the hand wheel 4 is rotated counter clockwise, the helicopter yaws counter clockwise; just as simply as in the case of the operational mode of a steering wheel of a car. Preferably, the yaw control axis y-y is symmetrically positioned substantially in correspondence of the ratable mounting of said intermediate control head assembly 4 on said main control column 2, and is substantially parallel to said collective pitch control axis 1-1.

The throttle control axis t-t, about which are made rotable each of the handles 3s, 3d, substantially is the respective longitudinal axis t_s-t_s, t_d-t_d of each of said handles 3s, 3d. In figure 8, 11 and 19, with reference to the embodiments herein described as a way of illustrative example but not intended to be construed as limitative of the scope of protection, it is shown how each of the handles 3 s, 3d is respectively rotable about a collective pitch control axis l_s-l_s, Id-I_d-

Said collective pitch control axes are substantially orthogonal to the plane formed by the longitudinal axes t_s-t_s, t_d-t_d respectively of said handles 3s, 3d.

In fig. 21 it can be understood how the left and right cyclic pitch control axis r-r preferably passes through a roll pivot section P of said main control column 2, located on a substantially intermediate sector thereof.

The left and right cyclic pitch control axis r-r is preferably substantially parallel to the collective pitch control axis 1-1.

The forward and backward cyclic pitch control axis f-f is preferably substantially orthogonal to the left and right cyclic pitch control axis r-r.

Preferably, the forward and backward cyclic pitch control axis f-f is substantially inferiorly positioned with respect to the pivot section P through which the left and right cyclic pitch control axis r-r passes, in correspondence of the mounting of the main column 2 on the floor of the helicopter.

When controlling the roll attitude and/or the pitch attitude of the helicopter, respectively by rotating said main control column 2 of an angle δ and/or γ around the left and right cyclic pitch control axis r-r and/or the forward and backward cyclic pitch control axis f-f, preferably the intermediate control head assembly 4 moves rigidly with the moving part of the main control column 2.

Accordingly, the main control column 2 feels the overall forward and backward and left and right movements, imparted by operation of the pilot 50 on said first and second grips means 3s, 3d. The output means, apt to responsively provide the main rotor 10 and/or the throttle body and/or the tail rotor 11 with a respective control command thanks to an interconnection to transmitting means apt to transmitting said control commands to the main rotor 10 and/or the throttle body and/or the tail rotor 11, may be of the displaceable kind. With reference to a drive system incorporating substantially mechanical or electro-mechanical transmitting means, push-rods 16 or ropes are pivotally attached to movement redirection and/or conversion means, such as levers 17. The levers 17 can have multiple arms forming an angle, with a fulcrum at the apex of said angle.

These angle-shaped levers typically are crank bells pivotally connected at either arm to a first and a second reciprocating push-rods, so that when the first push- rod is pulled, the bell crank rotates about its fulcrum, proportionally pulling at the second push-rod.

The transmitting means preferably comprise servomechanisms comprising velocity and/or position feedback devices, and preferably actuators, in order to affect the motion of said main rotor 10 and/or said throttle body and/or of said tail rotor 11, according to the regulation settings as imposed by the pilot.

More specifically, in a fly-by- wire variation of the drive system according the present invention, wherein physical controls of the aircraft are replaced with a substantially electrical interface, the above servomechanisms can comprise transducers 18 connected to respective output means; substantially electrical control lines 20 connecting said transducers 18 to an integrated control unit 19; actuators 22 connected to the mechanical functions of the main rotor 10 and/or the throttle body and/or the tail rotor 11; and substantially electrical power lines 21 connecting the actuators 22 to the integrated control unit 19.

The actuators 22, apt to transform an electrical input signal into motion, can be of any conventional type suitable to perform the required function.

Incidentally, such actuators can be for instance electromechanical actuators, pneumatic actuators; hydraulic actuators; piezoelectric actuators; of the step-by-step kind or similar.

The integrated control unit 19 is substantially a central processing unit comprising a power converter box.

A further objective of the present invention is to introduce a helicopter, comprising a drive system such as claimed hereafter and hereabove described according to two embodiments and respective variants thereof.

In a helicopter incorporating a drive system according to the present invention, the resulting operative position of the pilot is substantially symmetrical.

Moreover, by virtue also of the introduction of suitable kinematics mirroring all movements from one handle to the other, even when one hand leaves its operative position, all controls can be easily reached for and operated by the other hand remaining on the all integrated arrangement 1. During cruising in steady conditions, in particular, the pilot 50 can advantageously relax holding the single, integrated control arrangement 1 at one handle only of the two possible handles, by one sole hand. A broad panel of new possible users could be captured in the relevant market thanks to the fact that the present invention makes helicopter piloting advantageously much more user-friendly than the conventional fashion of the prior-art system.

Advantageously, virtually no substantial, expensive design change is needed to accommodate the drive system according to the present invention in an already existing helicopter, since interfaces are not substantially altered.

To the above-described helicopter drive system, as well as to a helicopter incorporating such a system, a person skilled in the art, in order to satisfy further and contingent needs, may effect several further modifications and variants, all however encompassed by the protective scope of the present invention, as defined by the appended claims.

Claims

1. Helicopter drive system for controlling main rotor (10) collective pitch; main rotor cyclic pitch; throttle and tail rotor pitch, comprising one single, all integrated control arrangement means (1); comprising: - a main control column (2), said column being rotable about a forward and backward cyclic pitch control axis (f-f) and about a left and right cyclic pitch control axis (r-r); first throttle grip means (3d, 3s) associated to said main control column (2), rotable about a throttle control axis (t-t); - second collective grip means (3d, 3s) associated to said main control column

(2), rotable about a collective pitch control axis (1-1); the overall configuration being such that said all integrated control arrangement has at least four degrees of freedom (β, γ, δ, α) respectively for the control of main rotor collective pitch; main rotor fore and aft cyclic pitch; main rotor left and right cyclic pitch and throttle; and is operable by a pilot (50) by either or both of the hands as desired; said main control column (2) feeling the overall fore-aft and left-right movements imparted by said pilot (50) by operation on said first and second grips means (3s, 3d); the selective movement of said main control column (2) and/or of said grip means (3s, 3d) affecting respective output means apt to responsively provide said main rotor (10) and/or said throttle with a respective control command.

2. Helicopter drive system according to claim 1, wherein said one single, all integrated control arrangement (1) is symmetrically disposed with respect to the operative driving position of said pilot (50).

3. Helicopter drive system according to claim 1 and 2, wherein said first and second grip means (3s, 3d) are associated to said main control column 82) through an intermediate control head assembly (4), mounted on said main control column (2).

4. Helicopter drive system according to one of claims from 1 to 3, said one single, all integrated control arrangement (1) being apt to also control the tail rotor pitch, and thus the yaw attitude of said helicopter, through said intermediate control head assembly (4).

5. Helicopter drive system according to claim 4, wherein said intermediate control head assembly (4) is rotably mounted on said main control column (2) so as to be pivotable about a yaw control axis (y-y) for controlling said yaw attitude (ε) of said helicopter.

6. Helicopter drive system according to claim 4 or 5, wherein said intermediate control head assembly is operable on said control column (2) as a rotable hand wheel (4), the selective rotational movement (ε) of said hand wheel (4) with respect to said main control column (2) affecting respective displaceable output means apt to responsively provide said tail rotor (11), and transmit thereto, with a respective, proportional control command.

7. Helicopter drive system according to claim 5 or 6, wherein said yaw control axis (y-y) is substantially in correspondence of the ratable mounting of said intermediate control head assembly (4) on said main control column (2), and is substantially parallel to said collective pitch control axis (1-1).

8. Helicopter drive system according to one of the claims from 1 to 7, wherein said first and second grip means are concomitantly seizable handle levers (3s, 3d).

9. Helicopter drive system according to claim 8, wherein said handles (3s, 3d) are respectively ratable about said throttle control axis (t-t), said throttle control axis (t-t) substantially being the respective longitudinal axis (t_s-t_s, td-ta) of each of said handles (3s, 3d).

10. Helicopter drive system according to claim 8 or 9, wherein said handles (3s, 3d) are respectively ratable about said collective pitch control axis (1-1), said collective pitch control axis (1-1) being substantially orthogonal to the plane formed by said longitudinal axes (t_s-t_s, ta-ta) of said handles (3s, 3d).

11. Helicopter drive system according to one of the claims from 1 to 10, wherein said left and right cyclic pitch control axis (r-r) substantially passes through a roll pivot section (P) of said main control column (2), located on a substantially intermediate section of said main control column (2).

12. Helicopter drive system according to one of the claims from 1 to 11, wherein said left and right cyclic pitch control axis (r-r) is substantially parallel to said collective pitch control axis (1-1).

13. Helicopter drive system according to one of the claims from 1 to 12, wherein the forward and backward cyclic pitch control axis (f-f) is substantially orthogonal to said left and right cyclic pitch control axis (r-r).

14. Helicopter drive system according to one of the claims from 11 to 13, wherein said forward and backward cyclic pitch control axis (f-f) is substantially inferiorly positioned with respect to said pivot section (P) through which said left and right cyclic pitch control axis (r-r) passes.

15. Helicopter drive system according to one of the claims from 3 to 14, wherein, when controlling the roll attitude (δ) or the pitch attitude (γ) of said helicopter respectively by rotating said main control column (2) around said left and right cyclic pitch control axis (r-r) and/or said forward and backward cyclic pitch control axis (f- f), said intermediate control head assembly (4) moves rigidly with the moving section of said main control column (2), said main control column (2) feeling the overall forward and backward and left and right movements imparted by operation of said pilot (50) on said first and second grips means (3s, 3d).

16. Helicopter drive system according to one of the claims from 4 to 15, wherein said output means, apt to responsively provide said main rotor (10) and/or said throttle and/or said tail rotor (11) with a respective control command, are displaceable and interconnected to transmitting means apt to transmitting said control commands to said main rotor (10) and/or said throttle and/or said tail rotor (11).

17. Helicopter drive system according to claim 16, wherein said transmitting means comprise servomechanisms comprising velocity and/or position feedback devices (18,22) to affect motion of said main rotor (10) and/or said throttle and/or said tail rotor (11).

18. Helicopter drive system according to claim 17, wherein said servomechanisms comprise transducers (18) connected to respective output means; substantially electrical control lines (20) connecting said transducers (18) to an integrated control unit (19); actuators (22) connected to the mechanical functions of said main rotor (10) and/or said throttle and/or said tail rotor (11); and substantially electrical power lines (21) connecting said actuators (22) to said integrated control unit (19).

19. Helicopter comprising a drive system according to one of the claims from 1 to 18.