GB2330561A

GB2330561A - Rotating undercarriage wheels prior to landing

Info

Publication number: GB2330561A
Application number: GB9722516A
Authority: GB
Inventors: Muhammed Abdul Bashar
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-10-24
Filing date: 1997-10-24
Publication date: 1999-04-28
Also published as: GB9722516D0

Abstract

Landing gear for aeroplanes are provided comprising means for driving at least one wheel in a direction corresponding to the trajectory of the aeroplane. Either vanes or a motor 4, may be used to drive the wheels. The motor may be controlled by a logic circuit comprising means 3 for producing a signal indicating that the landing gear is down and a sensor 1, indicating that the wheel has touched the ground. A true airspeed sensor 5, may be used to control the motor so that the wheels are caused to spin so that the peripheral speed of the wheels matches the air speed of the aeroplane immediately before touchdown. Reference is made to mechanical connections between wheels so that a single motor may drive all the wheels. Alternatively, separate, selectively operable, motors may drive respective wheel sets.

Description

AEROPLANE LANDING GEAR The invention relates to the landing gear of conventional aeroplane and, in particular, to three axis aeroplanes.

Due to the excessive wear of tyres during landing, aviation laws require that aeroplane tyres are replaced on a regular basis after a certain number ofjourneys.

Whilst some wear does occur on take off, most of the wear occurs on landing due to the sudden impact of the tyres on the landing strip.

It is an object of the present invention to substantially reduce the arnount of wear on the tyres caused on landing and thereby to increase the service life of the aeroplane tyres.

In the landing gear of a conventional aeroplane, the wheels are free to rotate but are idle until touch down. The relative speed of the tyre at the point of contact and the ground is equal to the speed of the aeroplane over the ground The present inventor proposes to reduce the wear on aeroplane tyres, therefore, by rotating the wheels before touch down and thereby reducing the relative speed between the periphery of the tyre, at point of contact, and the ground.

Accordingly, the invention provides aeroplane landing gear comprising at least one wheel having means for driving said wheel or at least one wheel to rotate in a direction corresponding to the trajectory of the aeroplane. By ensuring that the or each wheel is rotating before touching the ground, there is a reduction in the impact on the wheel and a corresponding reduction in the wear on the tyre.

In its simplest form the invention is achieved by attaching a vane to the or each wheel which is constructed so that, once the landing gear is lowered from the plane the wheel rotates in the appropriate direction.

In an embodiment, the landing gear comprises a motor associated with at least one wheel for driving at least one wheel to rotate in a direction corresponding to the trajectory of the plane. The motor may be controlled so as to drive the wheel shortly before landing and to disconnect once the wheel or all the wheels have touched the ground It is intended that the term 'landing' relates to a period of time extending before touch down as the aeroplane approaches the ground The invention also provides apparatus for use with aeroplane landing gear, comprising a motor adapted to drive at least one wheel of an aeroplane and operative to drive the or each wheel during a time period during landing and before the wheels touch the ground The apparatus may comprise control means adapted to switch the motor on and off so as to disconnect power from the wheels once the or each wheel has touched the ground. The apparatus may comprise a wheel touch down sensor or one for each wheel or set of wheels; power to the or each motor being disconnected dependent on a signal from the or each wheel touch down sensor.

In a particularly advantageous embodiment control means are provided whereby the speed of rotation of the wheels is matched to the speed of the plane. The control means may receive air speed data from an air speed sensor of the aeroplane and thereby the motor or motors can be controlled so as to drive the wheels to rotate at a speed corresponding to the velocity of the plane over the ground The relative speed of the tyre, at the point of contact, and the ground can be reduced substantially to zero if the peripheral speed of the wheel immediately before touch down is equal to the air speed of the aeroplane.

Whilst a motor may be provided for each wheel or each set of wheels, in a preferred embodiment a single motor is associated with a first wheel or set of wheels which touch the ground first on landing. The provision of only one motor will result in a considerable weight saving The remaining wheels may be drivingly connected or connectable with the first wheel or wheels. In particular a second wheel or set of wheels may be connectable with the first wheels only once the first wheels have touched the ground. Thus the motor is not required to drive the second wheels, which are driven by the first wheel or wheels which are in contact with the ground. There is a considerable weight saving as a less powerful motor is required The invention will now be described in more detail and with reference to the accompanying drawings, in which: Figure 1 is a schematic of a control circuit forming part of the landing geai- for the front wheel of a plane, operative in accordance with the present invention.

Figure 2 is a schematic of a control circuit operative in accordance with the present invention and forming part of the landing gear of the rear wheels.

Figure 3 is a schematic side view of an embodiment ofthe present invention.

When conventional aeroplanes come in to land, they decelerate to as low a speed as possible within specific safety limits. During the landing procedure, the landing gear, which is usually raised into the body of the plane during the flight, is lowered ready for touch down. Presently, the wheels of the landing gear are not driven and are idle until the aeroplane touches down.

In an embodiment of the present invention one or more motors are used to drive the wheels before landing.

Referring now to the drawings, figures 1 and 2 show logic diagrams for front and rear landing gear respectively, operative in accordance with the present invention.

In the present embodiment, the front and rear landing gear have individual motors driving the wheels under the control of a control circuit.

The landing gear are conventional and can take any known form. In the present embodiment the aeroplane is provided with a set of wheels at the front, left side rear wheels and right side rear wheels, however, the invention is equally applicable to aeroplanes having different arrangements.

The front landing gear is provided with a front wheels touch down sensor (FWTS) , I, which provides a positive output, i.e. a one, until touch down when the output thereof changes to a zero. The output of the FWTS is one input of a logical AND gate, 2. The other input of the AND gate is a front landing gear down (FLGD) signal 3, from either the flight instruments of the aeroplane or a separate sensor provided in the landing gear. The FLGD gives a zero during flight when the landing gear are raised and a positive one signal when, for example, the landing gear are fully lowered.

During landing, once the front landing gear are lowered, two positive signals are fed to the AND gate, 2, producing a positive output and switching on a front motor, 4. The motor, 4, spins the wheels under the control of a signal from the aeroplane's flight instruments, namely the aeroplane's true air speed (ATAS), 5 Thus in this embodiment, shortly before landing, the front wheels are rotating in a direction corresponding to the direction of the plane at an equal speed to the speed of the plane.

On touch down, the FWTS 1, signals a zero which together with the positive from the FLGD 3, produces a zero through the AND gate 2 and the motor 4 is effectively switched off so that no power is supplied to the motor whilst the aeroplane is on the ground. The zero through the AND gate 2 is also used to reset the FLGD ; via a reset connection 6. The FLGD signal 3 is reset so that take-offcan occur without the wheels being powered. The FLGD signal 3 remains zero until the landing gear are lowered again.

The logic diagram for the rear landing gear is shown in figure 2. In a similar fashion to the front landing gear logic diagram, a rear landing gear down (RLGD) signal generator 7 produces a positive one when the landing gear is lowered Two touch down sensors are provided for each set of wheels. The left (LRWDS) and right (RRDS) rear wheel down sensors, 8 and 9 respectively produce a positive one up to when touch down occurs for each set of wheels respectively. The outputs from the sensor 8 and 9 are the inputs of a logical NOR gate, 10. The NOR gate output is zero until both sensors 8 and 9 change to zero on touch down when the output from NOR gate 10, changes to a positive one. This positive one together with the positive one from the RLGD 7, produces a zero through the NAND gate 11 of figure 2, this effectively switches offthe rear motor or motors, 12. Similarly to the logic diagram for the front wheels, the zero from the NAND gate 11 also resets the RLGD 7 via reset line 13 The rear motor(s) may also be controlled to match the aeroplane true air speed by means of ATAS 14.

Figure 3 shows the side view of the wheel only of the landing gear. A vane 15 on one or both sides of the wheel drives the wheel to rotate in the direction of arrow A as the aeroplane moves through the air in the direction of arrow B. The vane can take any convenient form as long as the wheel thereby rotates in a direction corresponding to the trajectory of the aeroplane, that is, that the direction of rotation of the wheel reduces the relative speed between the periphery of the wheel at the point of contact and the ground. One or more vanes can either alone to achieve the desired rotation of the wheels or can be used in combination with one or more motors so as to assist the motors and thereby reduce the power requirements of the motors.

The foregoing description of the invention is by way of example only and modifications may be made which will suggest themselves to those skilled in the art, without departing from the scope of the invention which is defined in the claims which follow In particular either the front or rear systems can be omitted or replaced by a mechanical connection between the wheels such that a single motor drives all the wheels. If separate motors are used for left and right rear wheel sets, then the motors can be selectively operated to remove power from their respective wheel sets dependant on whether those wheels have touched the ground.

Claims

CLAIMS 1. Aeroplane landing gear comprising a set of wheels, at least one wheel having means for driving said wheel, or at least one said wheel, to rotate in a direction corresponding to the trajectory of the aeroplane.
2. Aeroplane landing gear as claimed in claim 1, wherein at least one wheel or set of wheels comprises a vane or vanes thereon constructed such that the vanes drive said wheel or wheels to rotate in a direction corresponding to the trajectory of the aeroplane.
3. Aeroplane landing gear as claimed in claim 1 or 2, wherein at least one wheel or set of wheels has a motor associated therewith for driving said wheel or wheels to rotate at least during a time period during landing and before the wheels touch the ground
4. Apparatus for use with aeroplane landing gear comprising a motor adapted to drive at least one wheel of an aeroplane and operative to drive the or each wheel during a time period during landing and before the wheels touch the ground
5. Apparatus as claimed in claim 4, and comprising control means adapted to switch said motor on and off so as to disconnect the power from the wheels once the wheel or all the wheels have touched the ground.
6. Apparatus as claimed in claim 5, comprising a wheel touch down sensor, power from the motor being disconnected dependent on a signal from the wheel touch down sensor
7. Apparatus as claimed in any one of claims 4 to 6, wherein control means are provided whereby the speed of rotation of the wheels is matched to the speed of the plane.
8. Apparatus as claimed in claim 7, wherein the control means receives air speed data from an air speed sensor of an aeroplane, whereby the motor can be controlled so as to drive said at least one wheel to rotate at a speed corresponding to the velocity of the plane over the ground
9. Aeroplane landing gear as claimed in claim 3, comprising a single motor associated with a first wheel or set of wheels which touch the ground first on landing
10. Aeroplane landing gear as claimed in claim 9, wherein the remaining wheels or wheel sets are drivingly connected or connectable with the first wheel or wheels
11. Aeroplane landing gear as claimed in claim 10, wherein a second wheel or set of wheels is connectable with the first wheel or set of wheels only once the first wheels have touched the ground.
12. Apparatus and landing gear as herein before described with reference to the accompanying drawings.