Automated wheel turn speed adjustment system for aircraft landing aimed at reducing aircraft tire wear.

This patent refers to the aviation field, specifically to the landing phase of aircraft on the runway. Currently, there is no known system on any aircraft that resembles the one we're proposing. As such when an aircraft enters its landing phase its wheels have a rotation speed equal to zero upon contact with the runway.

Right now the main reason for tire wear that affects any type of aircraft ( be it for military or civilian use) is the contact between the aircraft's tires which have rotation speed of zero and the runway during landing.

Aircraft landing speed depends on a various set of factors however the most important ones are the speed and wingspan of the aircraft.

As a factor, landing speed varies inside a large interval, with a maximum of 160-170 knots ( around 300 km/h).

Aircraft wheels during landing have a rotation speed equal to zero, thus the tangential speed of the tire is also equal to zero.

The main cause that causes tire wear for aircraft is the contact of said tired with the runway during landing.

When the tire and runway make contact, the tire receives a tangential speed equal to that of the landing aircraft. All this happens within a very short time interval ( tenths of a second ) thus making the tire's tangential speed increase very rapidly from zero to nearly 300km/h.

Following this kinetic energy transfer to the tire a non-uniform wear phenomenon becomes manifest. This coupled with the powerful vibrations and rapid heating lead to a certain and progressive wear of the tire. In time this may lead to a tire explosion or other form of

malfunction that can in turn damage the entire landing gear assembly or even the aircraft itself.

The system we've designed proposes mounting an electric motor on each of the wheel axles ( the number of motors will be equal to the number of axles in the landing gear assembly) that are part of the landing gear. These motors will be commanded by a controller. After the landing gear is lowered the motor will spin the wheels thus giving the tire a tangential speed equal to the linear speed of the aircraft during landing.

This will happen for all the wheels that are part of the aircraft's landing gear assembly.

With this system in place when the tire makes contact with the runwasy the violent process that we've mentioned above will be greatly reduced or even completely absent. This in turn will lead to a reduction of tire wear that was a consequence of landing. ί The system is composed of a controller ( A - figure 1) which controls

electrical flow ( D - Figure 1) which in turns powers an electric motor (B - figure 1). The motor acts either directly or through a reductor / multiplicator on the wheel axle ( C figure 1) on which the wheels of the landing gear are fixed.

For larger aircraft there are multiple wheel pairs that are part of the landing gear and for that reason an electric motor will be assigned to each wheel pair.

The Controller ( A , figure 1) will have the following input parameters :

1 - landing speed, 2-landing gear position, 3 -information provided by pressure sensors on the landing gear assembly to be able to pinpoint the exact moment of contact with the runway , 4- altitude, 5-wheel spin speed provided by a rotation translator.

Depending on how the system is designed and on the type of aircraft other input parameters may be required.

When the landing gear is lowered the system starts up and enters a stand-by mode until the aircraft falls under a minimum flight altitude ( or awaits a different pre-set condition - this condition may be different depending on how the system is designed or on the type and size of the aircraft). The system then powers the electrical motors that will in turn begin spinning the landing gear wheels with a tangential speed equal to the linear speed of the aircraft.

Figure 2 presents a simplified schematic of an aircraft landing gear. Wheels (A-figure 2) are connected via an axle on which the breaking system (D-figure 2) is mounted. Also attached to the axle is the strut (B-figure 2)

The motor present in our proposed system (C-figure 2) will rotate the wheel axle allowing the wheels to reach a tangential speed equal to the landing speed of the aircraft.

Also attached to the wheel axle is a system of transmitters (F-figure 2)which will relay the wheel rotation speed back to the central controller thus creating a negative feedback within the system. The transmitters will also pinpoint the exact moment when the aircraft makes contact with the runway by transmitting the weight transmitted by the aircraft to the landing gear (E-figure 2). The rotation speed is maintained until the moment of contact between the landing gear and the runway. At that point in time pressure sensors will be triggered by the aircraft's weight pressing down on the landing gear.

Following this the controller can relay a signal to the motors, making them switch to a electric breaking mode. This in turn will assist the main breaking system reducing its wear. When the aircraft has completely stopped ( its forward speed is equal to 0) the system will deactivate.

Our system's fundamental principle permits the usage of a wide range of electric motors. These can be powered by alternating current or direct curent. Depending on the size of the aircraft one or more controllers might be needed.

The type and power of the motor that will be attached to the wheel axle as well as a possible energy reductor or multiplicator system will be decided upon in relation to the type of landing gear. By implementing this system the only source of tire wear will come from rolling across the runway. This will invariably lead to an increase in tire lifespan and a substantial cost reduction of costs for both the aircraft operating company as well as the airport administration.

In order to resist against the severe wear they are exposed to aircraft tires are very expensive and during a maintenance cycle they are replaced after approximately 240 flights.

The tires are usually changed every 8-12 months and a complete tire set for a Boeing 747 can cost upwards of 360.000 USD.

Of course these costs depend on the number of tires mounted on the landing gear and this in turn varies from one type of aircraft to another.

Also, another side effect of the severe tire wear during landing is the rubber deposits that are left behind on the runway after the aircraft itself has landed. Airport administrations periodically check for this rubber layer and execute extensive clean-ups to remove it which in turn adds high supplementary costs that could be avoided.