Rotating blades are used in different connections, inter alia for helicopters. Usually the intention with rotating blades is to provide lifting or thrusting power. Normally the power is transferred to the rotor blades by means of mechanical devices. Mechanical power transmission is bound by disadvantages in the form of mechanical loss in the power transferring mechanisms and mechanical loads that can result in wear and tear and material rupture.

Hub motors of several types are known and utilised in different occasions in order to obtain energy effective and space-saving drive systems. In such systems one attempts to avoid transmission systems having gears, axles, couplings etc. in order to reduce friction, weight and space requirements.

It is of particular interest to use electrical drive systems in which mechanical gear systems are completely avoided by using modern electronic control/management of the electric drive system. Such systems are inter alia known in electric cars and vehicles.

US 4,955,560 and US 4,702,437 illustrate examples of helicopters having electric motor operation, but conventional power transmission is indicated.

The publication US 4,807,830 shows an aircraft having an annular rotor in which it is a magnetic field to obtain a"frictionless"support during operation. The operation appears to be jet nozzles, but operation with electro magnets is indicated. However, any adequate solution in connection with helicopters of the type disclosed by the present invention is not described.

JP A2 6165479 describes an electric motor in which an annular rotor is driven by means of magnetism and electric power, but that this can be used in relation to a vertically/horizontally flying craft is not indicated.

One of the objects with the present invention will be to avoid mechanical friction and loads that can result in fracture in the rotor structure of a vertically/horizontally flying craft, in addition to simplify the transmission mechanism and minimise gears between the drive motor and the propulsion means (rotor, propeller, etc.). Moreover is the object to be able to regulate the position of the rotor centre in an easy way in connection with the manoeuvring of the craft.

Modern electric motor systems makes it possible today to"support"the rotor of the drive system in a magnetic field and thus avoid, in some instances, a comprehensive and expensive journalling system for the rotating axle, which in turn constitutes the drive shaft/transmission to a wheel, propeller, rotor or similar. In that this rotor portion for example consists of a permanent magnetic material, can electric transmission to this portion by use of brushes or other means likewise be avoided.

This magnetic field support will also contribute to a more soft transmission of impacts or else against the drive wheel, since a direct mechanical transmission of such impacts against the drive means is avoided and this will in turn reduce the number of wear parts in the system. The magnetic field gap can also be increased and be designed such that an optimal balance between the efficiency of the motor and the power/impact absorption that the magnetic field should be able to receive is obtained.

One feature of the invention is that by moving the stator system of the motor, then the rotor portion will follow and this may in an easy way be used for controlling or adjusting the propeller/rotor or similar in order to obtain the desired effect in respect of influencing the craft.

For example can this system be utilised in a helicopter of the type disclosed in WO 01/56879 Al, with the same applicant as the present invention, in which a helicopter can be adjusted and controlled by adjusting/displace the rotor centre relative to the gravitational axis of the helicopter.

This displacement/movement of the rotor centre can for example be performed by a set of actuators that displace the stator rings of an electric motor in the rotor hub. Thus a possibility for a very simplified complete drive system for a helicopter is provided in that the motor is laying within/forms the hub of the rotor and the"suspension"for the rotor is less friction and omit support points, gear or conventional suspension.

This invention thus also provides a possibility for a completely electric driven helicopter in which also a tail rotor can be electric driven. As current/energy source a generator driven by a turbine is a possibility, or a fuel cell, in which a very noiseless craft with extremely reduced, respectively none pollutive emissions is obtained.

In the following the invention will be described in detail with reference to the drawings, where: Fig. 1 shows from above the craft including the drive means according to the invention, Fig. 2 shows a cross sectional view along the line A-A in fig. 1.

The drive system operates in a body consisting of an upper portion 1 and a lower portion 2. The upper portion 1 and the lower portion 2 are kept in position by a connecting structure 3, such that the portions 1, 2, and 3 constitute the integrated body of the craft.

A number of rotor blades 4 are fixed to a rotor in the form of a magnetic ring 7. The magnetic ring 7 with the rotor blades 4 are initially resting on the lower portion 2.

Within the upper portion 1 of the body is an electromotor ring 5 arranged, which is able to generate a rotating electromagnetic field. A corresponding ring 6 is provided in the lower portion 2 of the body. The rings 5,6 are initially positioned with their rotational

centres in the rotational centre of the body and such that the magnetic ring 7 is laying therebetween.

The rings 5,6 are supplied with electric current from a power source onboard the craft so that a rotating electromagnetic field is created within the space between the rings 5, 6. The electric power source can be created by a jet turbine with a generator and where the jet stream in addition can be used to stabilise the craft. The rotational speed of the rotating magnetic field is allowed to be varied by means of known electromagnetic principles. When a rotating electromagnetic field is set up between the rings 5,6 the magnetic ring 7 with the rotor blades 4 will be elevated from the lower portion 2 and adopt a hovering or suspending position between the rings 5,6 due to the electromagnetic forces that are introduced between said rings. The magnetic ring 7 with the rotor blades 4 will follow the same rotational speed as the magnetic field that is set up within the rings 5,6. In this way the rotor system 4,7 rotates with a rotational speed governed by the rings 5,6 and in such a way that the rotor system is not touching the body portions 1,2 and 3 of the craft.

The electromotor rings 5,6 will be aligned such that they always are positioned directly opposite each other in the vertical plane. By displacing the rotational centre of the rings in the horizontal plane by means of a set of actuators 8, 9 (schematically indicated on fig. 2) the rotor system 4,7 will follow the rings 5,6 and adopt the same position in the horizontal plane. In this way an eccentric rotation relative to the body of the craft is obtained, which in turn provides a possibility for manoeuvring the craft like that described in WO 01/56879 Al.