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Title:
AIRCRAFT USING DUCTED FAN FOR LIFT
Document Type and Number:
WIPO Patent Application WO/2011/041991
Kind Code:
A2
Abstract:
An aircraft using ducted fan to create lifting force, containing control flaps (7) that produce at the bottom surface of the ring (4) surrounding the rotor (2), from a part of the air leaving the rotor (2), a wall jet held to the surface by the Coanda effect and flowing towards the outer perimeter of the ring (4). The bottom surface of the ring (4) is shaped in such a way that near the outer perimeter of the ring (4) the wall jet flows downwards to the ground. With a change of their position and/or shape of their surface with regard to the opposite surface of the ring (4), the control flaps (7) change the velocities and/or mass flow values of the wall jet in various places of the trailing edge (11) of the bottom surface of the ring (4). This way, changes of aerodynamic forces at different sides of the aircraft (1) are controlled and therefore its tilt and flight in the required direction.

Inventors:
JANDA ZDENEK (CZ)
Application Number:
PCT/CZ2010/000102
Publication Date:
April 14, 2011
Filing Date:
September 24, 2010
Export Citation:
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Assignee:
JANDA ZDENEK (CZ)
International Classes:
B64C39/00; B64C21/08
Domestic Patent References:
WO2005032939A12005-04-14
Foreign References:
GB912087A1962-12-05
DE29914928U12001-02-08
US20040164203A12004-08-26
Other References:
None
Attorney, Agent or Firm:
HAINZ, Miloslav et al. (Ruzicka & GuttmannVinohradska 37, Praha 2, CZ)
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Claims:
P a t e n c l a i m s

1. An aircraft using ducted fan to create lifting force comprising a rotor (2) surrounded by a ring (4), characterized in that the bottom surface of the ring (4) is shaped continuously from the rotor (2) towards the outer perimeter of the ring (4) in such a way that in the axial - radial cross-section it contains three consecutive path segments where in the first segment the tangent of the bottom surface of the ring (4) directs downwards from the rotor (2), in the second segment it directs upwards and in the third segment, up to the trailing edge (11), it directs downwards again, inside the central opening of the ring (4) there is a group of control flaps (7) arranged in such a way that between their surface and the opposite first segment of the bottom surface of the ring (4) they form a slot (12) for conversion of a part of the air flow leaving the rotor (2) to a wall jet held by the Coanda effect at the bottom surface of the ring (4) , and the control flaps (7) have controllably adjustable position and/or shape of their surface with regard to the opposite bottom surface of the ring (4) to ensure a change of the slot (12) geometry and therefore also the velocities and/or mass flow .values of the wall jet in various places of the trailing edge (11) of the bottom surface of the ring (4) .

Description:
Aircraft using ducted fan for lift

Field of Invention

This invention deals with aircraft in which the lifting force is produced by one central ducted fan (rotor in a ring) drawing air from above and pushing it downwards to the ground.

The flight direction of this aircraft is controlled by tilting of the aircraft, which produces a horizontal component of the total lifting force, inducing the aircraft to lateral, horizontal, movement in the required direction.

Background of the Invention

At present, aircrafts using a ducted fan to produce lifting force are made in diameters of up to one metre. Means of their control known so far are not sufficiently safe and effective for use in larger aircraft and for flights with a human crew.

Conventionally used means of controlling the tilt of a aircraft using ducted fan for lift are adjustable stator vanes for deflection of the air flow leaving the rotor from the axial axis. To achieve sufficient control moments, the centre of gravity of the aircraft must be over the ducted fan, with this type of control. This can only be ensured with the use of heavy body over ducted fan; however, this at the same time cause considerable resistance of the aircraft during flying, affect stability of the flight and limit air flow to the rotor and therefore its efficiency. Cyclic control of the rotor blades has been tested in the world for the tilt control, similarly to helicopters, but aircrafts using ducted fan for lift have a considerably smaller diameter of the rotor as compared to helicopters with comparable useful load, and therefore cyclic aerodynamic control forces take effect in a small distance from the aircraft's centre of gravity. This leads to big problems with flight stability and moreover this type of control is very complicated and subject to high dynamic stresses.

Summary of the Invention

The above mentioned disadvantages of the present state of the art are solved by an aircraft using ducted fan to produce lifting force, comprising a rotor surrounded by a ring, the substance of which consists in that the bottom surface of the ring is shaped continuously from the rotor towards the outer perimeter of the ring in such a way that in the axial - radial cross-section it contains three consecutive path segments where in the first segment the tangent of the bottom surface of the ring directs downwards from the rotor, in the second segment it directs upwards and in the third segment, up to the trailing edge, it directs downwards again, inside the central opening of the ring there is a group of control flaps arranged in such a way that between their surface and the opposite first segment of the bottom surface of the ring they form a slot for conversion of a part of the air flow leaving the rotor (2) to a wall jet held by the Coanda effect at the bottom surface of the ring, and the flaps have controllably adjustable positions and/or shape of their surface with regard to the opposite bottom surface of the ring to ensure a change of the slot geometry and therefore also the velocities and/or mass flow values of the wall jet in various places of the trailing edge of the bottom surface of the ring.

An aircraft according to the invention contains a group of control flaps inside the central opening of the ring that direct a part of the air leaving the rotor to a thin wall jet flowing on the bottom surface of the ring from the rotor to the trailing edge of the bottom surface of the ring and from there to the free space downwards to the ground. The wall jet is held at the bottom surface of the ring by the effect of underpressure caused by the so called Coanda effect.

The bottom surface of the ring means such a part of the ring surface that lies below the plane passing through the rotor blades. The bottom surface of the ring is shaped continuously from the rotor towards the outer perimeter of the ring in such a way that in the axial - radial cross-section it contains three consecutive path segments where in the first segment the tangent of the bottom surface of the ring directs downwards from the rotor, in the second segment it directs upwards and in the third segment, up to the trailing edge, it directs downwards again.

The control flaps are arranged in such a way that the position and/or shape of their surface can be adjusted in a controlled way with regard to the opposite first segment of the ring surface, e.g. by swivelling, moving or deformation.

Therefore, the control flaps determine the volume of air that flows from the rotor to the slot between each flap and the ring, changing the mass flow and/or velocities of the wall jet in the corresponding places of the trailing edge of the bottom surface of the ring. This causes changes of aerodynamic forces at the corresponding sides of the aircraft, which produce the required tilting moment for tilt and movement of the aircraft in the required direction.

The control of the tilt and therefore the flight direction of the aircraft in accordance with the invention does not require any heavy body over ducted fan or complicated cyclic mechanisms, and as the aerodynamic forces produced this way act near the outer perimeter of the aircraft, the new control is effective and precise. Therefore, the new control is suitable even for aircrafts with a human crew.

Brief Description of the Drawings

The invention ' will be further explained in a more detailed way with the use of its sample embodiment with reference to drawings where: figure 1 schematically shows a perspective view of an example of embodiment of an aircraft in accordance with the invention, and figure 2 shows a cross-section of the example of embodiment of an aircraft in accordance with the invention from fig. 1.

Description of the preferred Embodiment

As fig. 2 shows, in the middle of the aircraft I there is a rotor 2 driven by the engine 3_. The trailing edge 11_ of the bottom surface of the ring 4 is positioned on the outer perimeter of the ring _4. The ring is connected to the reinforcing ring 8_ through fixed radial vanes 5_. Swivelling radial vanes 6, ensuring control of heading of the aircraft around the axial axis, are attached to fixed radial vanes. The engine _3 is connected to the reinforcing ring 8 ^ through connection elements _9. Landing gear parts 10_ are connected to the reinforcing ring _8.

In this sample embodiment the aircraft 1 contains the swivelling control flaps 7_ that are connected to the fixed radial blades _5 in a rotary way. Between the swivelling control flaps 1_ and the bottom surface of the ring _ there is a slot 12.

The invention is not limited to its described and illustrated example of embodiment only, but it also comprises all adjustments and modifications that fall within the scope of the attached patent claim.




 
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