AU4452099A - Airpressure rotated aviation tyre - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT a a a a.

o* a oo Airpressure Rotated Aviation Tyre The following statement is a full description of this invention, including the best method of performing it known to me: -2- Airpressure Rotated Aviation Tyre (APRAT) This invention relates to improvements in devices to rotate aircraft wheels prior to touchdown.

On touchdown of an aircraft the at that point stationary tyres are accelerated within a very short period of time, resulting in extreme wear and tear of the tyres. Methods to rotate the wheels prior to touchdown by other means (motors etc.) require extensive and expensive modification of existing aircraft.

However there are previous patents dealing with the problem.

US Pat. 3529792 discloses an aircraft tyre with wedge-shaped bar structures as side profiles. Straight profiles are aerodynamically less efficient than curved profiles, they have less surface area.

US Pat. 3773283 covers profiles in the tread surface. The tread area is fairly small to be very efficient as well as the tyre has to be restructured to offer enough strengh.

US Pat. 3814354 is a power operated device, which is entirely different.

15 US Pat. 4061294 uses an auxiliary device to rotate the wheel.

US pat. 4385739 again uses an external device to affect wheel rotation.

US Pat. 5213285 Stanko used profiles within the tread pattern and shoulder profiles not extending past the widest part of the tyre. To enhance the efficiency of those profiles he is using a shute auxiliary device) to direct air flow unto the profiles.

Most other patents cover rim modifications. Since the rim is the centre of the wheel, and hence in an aerodynamically turbulent area, those modifications are probably more costly and less efficient.

These problems can be significantly reduced by the present invention which provides an airpressure rotated aviation tyre which has C-shaped profiles at the sidewalls of the tyre which increase the drag at the lower part of the tyre while reducing the drag on the upper part of the tyre respectively when exposed to airpressure produced by the slipstream of the landing aircraft, thus assisting tyre rotation in the desired direction prior to touchdown.

In the invention the tyre has multiple C-shaped profiles spread out preferably over both sidewalls so arranged that the imagined vertical axis through the C always points to the centre of the wheel, resulting in the rounded side of the C facing in the direction of the aircraft movement at the top of the sidewall and the open side of the C facing in the direction of the aircraft movement at the bottom of the tyre sidewall, thus resulting in increased drag at the bottom of the tyre and consequently rotation in the desired direction.

-3- The profiles are preferably curved inverted towards the sidewalls of the tyre at the leading edge in crossection and gradually sloping back to the sidewall at the trailing edge of the profile in crossection to enhance and reduce dragfactors respectively for the tyre.

The number of sideprofiles may vary due to type of wheel, aircraft undercarriage, operating conditions or any other factor as is deemed necessary, but should preferably take up as much as possible of the hight of the tyre sidewall(s) and be in sufficient numbers and size to be aerodynamically effective.

The profiles can be integral part of the tyre and manufactured in the same process with the tyre and be on both sides or either, depending on application.

To assist with understanding of the invention reference will now be made to the accompanying drawings which show an example of the invention.

In the drawings: :Fig. 1 shows an example of an APRAT viewed from the side Fig. 2 shows an APRAT from the top Fig. 3 shows an APRAT from the bottom Referring to Fig. 1, it illustrates the arrangement, size and shape of the sidewall profile 1 of the APRAT and the tyre position in relation to aircraft movment 2, airflow 3 and the resulting tyre rotation 4.

20 When the airflow meets the sidewall profile, the profile at the top of the sidewall will produces a lot less drag because of ist shape and crossection then the one at the bottom of the sidewall. The imbalance in forces will assist in rotation of the tyre by airpressure.

Referring to Fig. 2, is a view of the tyre from above 7 to illustrate the preferred crossection 5 of the sideprofile in relation to aircraft movement 2 and airflow 3.

Fig. 3 is a view of the APRAT from underneath 8 to illustrate the preferred shape of the sideprofile in crossection 6 to aircraft movement 2 and airflow 3.

The touchdown speed of a commercial airliner being in the vicinity of approx. 300 km ph, the at that point stationary tyres experience a very sudden acceleration resulting in extreme wear and tear.

Any amount of previous rotation will help to reduce this wear and tear and prolong tyre life respectively.

Claims (4)

1. An airpressure rotated aviation tyre which has C-shaped profiles at the sidewall(s) of the tyre which increase the drag at lower part of the tyre while reducing the drag at the upper part of the tyre respectively when exposed to airpressure produced by the slipstream of the landing aircraft, thus producing tyre rotation in the desired direction prior to touchdown.

2. An APRAT of claim I where the tyre has multiple C-shaped profiles spread out preferably over both sidewalls so arranged that the rounded side of the C-faces in the direction of the aircraft movement at the top of the tyre sidewall and open side of the C- faces in the direction of the aircraft movement at the bottom of the sidewall, thus resulting in an increased drag at the bottom of the tyre and consequently tyre rotation in the desired direction.

3. An APRAT of claim 1 with the sideprofiles being an integral part of the tyre, with the leading edge of sideprofiles being preferably sharp edged or inverted towards 1 5 the tyre sidwall and the trailing edge preferably gently sloping back to the sidewall taking up as much of the hight of the sidewall as practical and in sufficient numbers and size to be aerodynamically efficient.

4 A ug. 1999