Pivotable aircraft nose portion

The present invention relates to a method for reducing the length of the aircraft during operation. The present invention also relates to an aircraft of which the length may be reduced during operation.

BACKGROUND

The present invention relates generally to methods and apparatus for actuating an aircraft nose portion. Some conventional transport aircraft have nose portions that move relative to the rest of the aircraft. For example, the European Concorde supersonic aircraft has a nose portion that droops downwardly during approach and landing to give the pilot increased downward visibility when the aircraft is at a high angle of attack. Other aircraft have nose portions that move to allow access to the interior of the aircraft. For example, the Lockheed C-5 aircraft has a nose portion that swings upwardly to open the fuselage for loading and unloading. Other aircraft, such as those disclosed in U.S. Patent Nos. 3,150,849; 4,116,405; and 4,379,553 disclose nose portions that swing to the side to allow access to the aircraft interior. However, none of the foregoing designs address the issues addressed by the present invention.

US 3 335 981 discloses a retractable front landing gear for cargo aircraft, the aircraft having a removable nose pivotally attached thereto for movement thereof in a vertical plane. The nose is pivoted upward so as to able to access an opening to permit on-and-off loading of cargo through the opening. The known front landing gear does not address the issue of the constrainment of the size of the aircraft because of airport gate size limitations.

US 3 171 620 discloses a fighter jet provided with a nose portion hinged to the cockpit of the aircraft about a transverse horizontal axis so as to be capable of being lowered preparatory to landing so as to increase the pilot's downward vision and also hinged about a vertical axis capable of hinging said nose portion so that it can be swung back on the ground so as to shorten the length of the fuselage, particularly for use on board of an aircraft carrier. The known aircraft fuselage therefore has two hinges, one hinge for displacing the nose portion upward and downward and one hinge for displacing the nose portion backward and forward. Also this known aircraft fuselage does not address the issue of the constrainment of the aircraft because of airport gates size limitations.

It is therefore an object of the present invention to obviate the above identified drawbacks and to provide a commercial aircraft having a nose that is more optimally efficient aero dynamically while still being able to fit the aircraft at existing airport gates.

This object is achieved in the method as claimed in claim 1 and the aircraft as claimed in claim 14.

The present invention is directed toward methods and apparatus for actuating an aircraft nose portion. An aircraft in accordance with one aspect of the invention includes a fuselage having a longitudinal axis and a pitch axis generally transverse to the longitudinal axis. The fuselage includes a pressure bulkhead, a pressurized payload portion aft of the pressure bulkhead, and a nose portion forward of the pressure bulkhead. The nose portion is pivotable relative to the pressurized payload portion about a pivot axis generally parallel to the pitch axis while the pressurized payload portion is capable of being pressurized relative to a region external to the aircraft. The nose portion is pivotable between a first position and a second position, with the nose portion being generally aligned with the longitudinal axis when in the first position, and with the nose portion being inclined upwardly relative to the longitudinal axis when the nose portion is in the second position.

The aircraft can include a pivot support member projecting forward from the pressure bulkhead, with the pivot support member being received in a corresponding slot of the nose portion. A pivot pin can be pivotably coupled between the pivot support member and the nose portion, and an actuator can be operatively coupled to the nose portion to move the nose portion between the first and second positions.

The nose portion changes from a first configuration with the nose portion and the fuselage having a combined first length to a second configuration with the nose portion and the fuselage having a combined second length of 5 percent or more shorter than the first length. The nose portion pivots between the first and second configurations. In still a further aspect of the invention, the nose portion can be inclined upwardly at an angle of approximately 90 degrees relative to the longitudinal axis when it is in its second configuration.

The present invention is also directed toward a method for reducing a length of an aircraft during operation. The method includes flying the aircraft while the aircraft has a first length, landing the aircraft, and pivoting a nose portion of the aircraft upwardly to reduce the length of the aircraft to a second length 5 percent or more shorter than the first length. The method includes moving the aircraft with the second length relative to an unloading area, and unloading the aircraft at the unloading area only through one or more openings that are spaced apart from the nose portion.

The method may include at least partially sealing a pressurized portion of an aircraft fuselage so that the pressurized portion is capable of being pressurized relative to a region external to the fuselage. The fuselage has a longitudinal axis and a pitch axis generally transverse to the longitudinal axis, and the method includes pivoting a nose portion of the aircraft relative to the pressurized portion about a pivot axis that is generally parallel to the pitch axis. Pivoting the nose portion includes pivoting the nose portion from a first position with the nose portion generally aligned with the longitudinal axis to a second position with the nose portion inclined upwardly relative to the longitudinal axis while the pressurized portion is capable of being pressurized relative to a region external to the fuselage. In a further aspect of the invention, the nose portion can be pivoted downwardly while the aircraft is in flight or in preparation for flight.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a rear isometric view of an aircraft having a movable nose portion in accordance with an embodiment of the invention.

Figure 2 is a front isometric view of an aircraft having a movable nose portion in accordance with another embodiment of the invention.

Figure 3A is a partially schematic, side elevational view of an aircraft having a movable nose portion generally aligned with a longitudinal axis of the aircraft.

Figure 3B is a partially schematic, side elevational view of an embodiment of the aircraft shown in Figure 3A with the nose portion inclined upwardly in accordance with an embodiment of the invention.

Figure 3C is a partially schematic, side elevational view of an aircraft having a nose portion inclined downwardly in accordance with another embodiment of the invention.

Figure 4A is a partially schematic, side elevational view of an aircraft having a movable nose portion aligned with a longitudinal axis in accordance with yet another embodiment of the invention.

Figure 4B is a partially schematic, side elevational view of the aircraft shown in Figure 4A with the nose portion inclined upwardly in accordance with an embodiment of the invention.

Figure 5 is a partially schematic, top plan view of an aircraft having a movable nose portion and being positioned at a terminal in accordance with an embodiment of the invention.

DETAILED DESCRIPTION

The present disclosure describes methods and apparatus for moving an aircraft nose portion to effectively shorten the length of the aircraft and allow the aircraft to be parked at terminals that have a limited capacity for long aircraft. Many specific details of certain embodiments of the invention are set forth in the following description and in Figures 1-5 to provide a thorough understanding of these embodiments. One skilled in the art, however, will understand that the present invention may have additional embodiments, and that the invention may be practiced without several of the details described below.

The aerodynamic efficiency of an aircraft depends, in part, upon the shape of the aircraft nose. Longer, "skinny" noses generally result in lower aircraft drag, but also extend the total aircraft length if all other parametric variables are held constant. Total aircraft length is typically constrained by airport gate size limitations. Accordingly, conventional aircraft designs typically include a compromise between aircraft length, seat count, and high-speed drag. For example, many commercial transport aircraft have noses that are less than optimally efficient because they are blunted in order to fit the aircraft at existing airport gates.

Figure 1 is a rear isometric view of an aircraft 110 having a pivoting nose portion 120 in accordance with an embodiment of the invention. In one aspect of this embodiment, the aircraft 110 can be configured for cruise at supersonic Mach numbers, and can include a fuselage 130 elongated along a longitudinal axis 131. The aircraft 110 can further include a swept delta wing 115, canards 114, tails 111, and propulsion systems 113 integrated with an aft body 112. In other embodiments, the aircraft 110 can include other configurations and/or can have other cruise Mach numbers, such as a subsonic cruise Mach number above about 0.95. In any of these embodiments, the aircraft 110 can yaw about a yaw axis 132 and pitch about a pitch axis 133. The nose portion 120 is pivotable about an axis generally parallel to the pitch axis 133 to effectively shorten the length of the aircraft 110 on the ground, as described in greater detail below with reference to Figures 2-5.

Figure 2 is a front isometric view of another embodiment of the aircraft 110 having a single tail 111 and no canards. The aircraft fuselage 130 includes a forward pressure bulkhead 134 which defines the forwardmost extent of a pressurized payload portion 138 of the aircraft 110. The pressurized payload portion 138 can include a flight deck 136 and a cabin portion 180 positioned aft of the flight deck 136. The flight deck 136 can include a windshield 135, and the cabin portion 180 can include windows 182 and doors 181. In one embodiment, at least one of the doors 181 on the left side of the aircraft (not visible in Figure 2) can be accessed by a jetway 141 in a conventional manner to allow passengers to enter in and exit the aircraft 110.

The aircraft 110 can further include a pivot support member 150 projecting forward of the forward pressure bulkhead 134. The pivot support member 150 can be pivotably coupled to the nose portion 120 to allow the nose portion 120 to rotate relative to the pressurized payload portion 138. Accordingly, the nose portion 120 can include a slot 124 that receives the pivot support member 150, as described in greater detail below with reference to Figures 3A-5. In other embodiments, the aircraft 110 can include other arrangements that also allow motion (such as rotational motion) of the nose portion 120 relative to the rest of the aircraft 110.

Figure 3A is a partially schematic, side elevational view of a forward portion of an aircraft 110 having a pivotable nose portion 120 that pivots in accordance with an embodiment of the invention. The nose portion 120 of the aircraft 110 can include an external skin 121 which, for purposes of illustration, has been shown partially removed in the region where the nose portion 120 joins with the rest of the fuselage 130. The nose portion 120 can be joined to the pivot support member 150 with a pivot pin 152 so as to rotate relative to the fuselage 130 about a pivot axis 151 that is at least approximately parallel to the pitch axis 133 (Figure 1) of the aircraft 110. In a further aspect of this embodiment, the aircraft 110 can further include an actuator 153 coupled between the pivot support member 150 and the nose portion 120 to rotate the nose portion 120 relative to the fuselage 130. In other embodiments, the aircraft 110 can include other arrangements for moving the nose portion 120. In any of these embodiments, the nose portion 120 is movable between a first position (shown in Figure 3A) with the nose portion 120 generally aligned with the longitudinal axis 131 of the aircraft 110, and a second position with the nose portion inclined relative to the longitudinal axis 131, as described in greater detail below with reference to Figure 3B.

In one aspect of an embodiment of the aircraft 110 shown in Figure 3A, the nose portion 120 can be unpressurized and can house components, such as a radar 122, that do not require a pressurized environment during aircraft operation. In an alternative embodiment, the nose portion 120 can be pressurized to the same level as the pressurized payload portion 138. For example, the nose portion 120 can be coupled with a flexible, fluid-tight coupling to the pressurized payload portion 138. In another alternate embodiment, the nose portion 120 can be pressurized to an intermediate level above the pressure external to the aircraft 110, but below the pressure in the pressurized payload portion 138. In either alternate embodiment, the nose portion 120 can house components that operate in a pressurized or partially pressurized environment.

In a further aspect of an embodiment of the aircraft 110, a restraint 160 (shown schematically in Figure 3A) can be operatively coupled to the nose portion 120 to prevent inadvertent movement of the nose portion 120 from the first position shown in Figure 3A. For example, the restraint 160 can include a mechanism generally similar to a conventional latch for an aircraft access door or landing gear hatch. The restraint 160 can be selectively engaged with the nose portion 120 to prevent movement of the nose portion 120 relative to the fuselage 130, and disengaged with the nose portion 120 to allow for movement of the nose portion 120 relative to the fuselage 130.

The aircraft 110 can further include a camera 170 positioned to capture a forward-facing image from the aircraft 110: Accordingly, the camera 170 can be coupled to the flight deck 136 to provide the pilot with a video image of the region forward of the aircraft 110 when the pilot's view is obstructed by the nose portion 120 in its raised position. In one aspect of this embodiment, the camera 170 can be mounted to the fuselage 130. Alternatively, the camera 170 can be mounted to a landing gear 116 or a part of the nose portion 120 that becomes exposed when the nose portion 120 is moved to its second or raised position. In any of these embodiments, the camera 170 can move between a deployed position (shown in Figure 3A) and a stowed position (for example, with the camera 170 retracted into the fuselage 130).

Figure 3B is a partially schematic, side elevational view of the aircraft 110 described above with the nose portion 120 in its second, raised position. In one embodiment, the nose portion 120 can be rotated relative to the longitudinal axis 131 by extending the actuator 153. When the nose portion 120 is in the raised position, it can have a non-zero inclination angle 123 relative to the longitudinal axis 131. In one aspect of this embodiment, the inclination angle 123 can be approximately 90 degrees, and in other embodiments, the inclination angle 123 can have other values. In any of these embodiments, raising the nose portion 120 effectively shorters the overall length of the aircraft 110, as described in greater detail below with reference to Figure 5.

Figure 3C is a partially schematic, side elevational view of the aircraft 110 with the nose portion 120 moved to a third, drooped position. For example, the nose portion 120 can have a negative inclination angle 123a relative to the longitudinal axis 131. Accordingly, the pilot's visibility through the windshield 135 can be improved during high angle of attack operation, such as during approach and landing.

Figures 4A and 4B illustrate an aircraft 110 having a nose portion 420 that is movable between two positions in accordance with another embodiment of the invention. Referring first to Figure 4A, the aircraft 110 can include a fuselage 130 having a forward pressure bulkhead 434 that supports a pivot support member 450. The nose portion 420 can be pivotably coupled to the pivot support member 450 to rotate about a pivot axis 451 in a manner generally similar to that described above with reference to Figures 3A-B. Accordingly, the aircraft 410 can include an actuator 453 coupled between the pivot support member 450 and the nose portion 420 to rotate the nose portion 420 between a lowered position (shown in Figure 4A) with the nose portion 420 generally aligned with the longitudinal axis 131, and a raised position (described in greater detail below with reference to Figure 4B).

Referring now to Figure 4B, the nose portion 420 can be moved to its raised position by extending the actuator 453 to rotate the nose portion 420 about the pivot axis 451. In one embodiment, the nose portion 420 can be rotated to an inclination angle 423 that is approximately 90 degrees relative to the aircraft longitudinal axis 131. Alternatively, the inclination angle 423 can have other values, greater or less than 90 degrees, in other embodiments. In another embodiment, the nose portion 420 can have an aft-facing surface 425 (such as a rim) that engages (and optionally seals against) a corresponding forward-facing surface 437 of the fuselage 130 to prevent the nose portion 420 from over-rotating downwardly when it is returned to its first position (Figure 4A). In any of these embodiments, raising the nose portion 420 effectively decreases the overall length of the aircraft 110, which can enhance the compatibility of the aircraft with conventional terminal structures, as described below with reference to Figure 5.

Figure 5 is a plan view of the aircraft 110 described above with reference to Figure 1 having a nose portion 120 generally similar to that described above with reference to Figures 2-3C. Alternatively, the aircraft 110 can have an overall configuration generally similar to that shown in Figure 2, and/or a nose portion generally similar to that described above with reference to Figures 4A-B. In any of these embodiments, the aircraft 110 can be positioned proximate to a terminal structure 540 for loading and/or unloading. The region adjacent to the terminal structure 540 can include a parking area (for aircraft loading and unloading) extending for a distance P away from the terminal structure 540. A taxi area T can be positioned immediately behind the parking area and can be sized to allow other aircraft to pass behind the aircraft 110 while the aircraft 110 is parked at the terminal structure 540. Accordingly, aircraft regulations (for example, those promulgated by the International Civil Aviation Organization, or ICAO) require that the aircraft 110 not extend aft into the taxi area T while parked at the terminal 540. For example, many conventional aircraft parking areas have a distance P of 80 meters. Thus, aircraft having a length of greater than 80 meters cannot park at the terminal structure 540 without encroaching on the taxi area T. Even aircraft having a length slightly less than 80 meters may not be able to park at the terminal structure 540 without encroaching on the taxi area T because the aircraft must typically be separated from the terminal structure 540 by a selected offset distance, such as from about 4.5 meters to about 9 meters or more.

As shown in Figure 5, the aircraft 110 can have an overall length L1 when the nose portion 120 is in its first or lowered position (shown in broken lines in Figure 5) and will accordingly encroach on the taxi area T. When the aircraft 110 has the nose portion 120 moved to its second or raised position (as shown in solid lines in Figure 5), the overall length of the aircraft 110 can be reduced by L3 (approximately the length of the nose portion 120), from L1 to L2. Accordingly, the aircraft 110 can be moved close enough to the terminal structure 540 so that the aft portion of the aircraft 110 does not extend into the taxi area T.

The length L3 is 5 percent or more of the overall length L1 of the aircraft 110. For example, in one particular embodiment, the length L3 can be approximately 10 percent of the overall length L1 of the aircraft 110. In another embodiment, the length L3 can approximately 13 percent of the overall length L1 of the aircraft 110. In a particular embodiment, the aircraft 110 can have a length L1 (with the nose portion 120 in its first position) of approximately 85 meters and a length L2 (with the nose portion 120 in its raised position) of approximately 74.5 meters. In other embodiments, the actual dimensions and the percentage of the overall aircraft length occupied by the movable nose portion 120 can have other values, so long as the overall length of the aircraft 110 can be reduced by 5 percent or more by moving the nose portion 120. In any of these embodiments, the distance P between the terminal structure 540 (or another obstacle at the same elevation as the nose portion 120) and the aftmost point of the aircraft 110 can be less than the initial length L1 of the aircraft 110.

Operation of an embodiment of the aircraft 110 is described below with reference to Figures 1-5. During cruise operation, the aircraft 110 can have the nose portion 120 in the first position, generally aligned with the longitudinal axis 131 as shown in Figures 1, 3A and 4A. When the aircraft is on landing approach, the nose portion 120 can be drooped, as shown in Figure 3C. Alternatively, the nose portion can remain in the position shown in Figure 3A or 4A. Upon landing, the aircraft 110 can taxi with the nose portion 120 in either the first position (Figure 3A or 4A) or the third position (Figure 3C). As the aircraft nears the gate area (for example, just prior to turning directly toward the terminal structure 540 shown in Figure 5), the pilot can issue a command to raise the nose portion 120 from the first position to the second position. The pilot's command can unlock the restraint 160 (Figure 3A) and activate the actuator 153 (Figure 3A). The nose portion 120 can accordingly move from the first position to the second or raised position shown in Figures 3B and 4B. The restraint 160 can then lock the nose portion 120 in the second position. The aircraft 110 can then continue forward toward the terminal structure 540 with guidance from either a ground lineman or the camera 170. After the aircraft 110 has been unloaded and/or loaded and pushed back from the terminal structure 540, the nose portion 120 can be returned to the lowered position for taxi and takeoff.

One feature of an embodiment of the aircraft described above with reference to Figures 1-5 is that the nose portion can be raised to an inclined position relative to the longitudinal axis of the aircraft while the aircraft is on the ground. An advantage of this arrangement is that the overall length of the aircraft can be reduced and can make the aircraft more manageable when on the ground. For example, the aircraft can be positioned at gates and/or other unloading areas that typically require an aircraft length shorter than the overall length L1 of the aircraft shown in Figure 5.

Another advantage of the foregoing features is that the aircraft can have an improved efficiency at cruise Mach numbers. For example, the aircraft can have a greater fineness ratio (aircraft length divided by aircraft diameter), which can improve the aerodynamic efficiency relative to a blunt nosed aircraft. Accordingly, the aircraft can be more efficient to operate and can therefore reduce operating costs.

Still another advantage of the foregoing features is that the nose portion can be configured as a separate sub-assembly and can be attached to the aircraft relatively late in the aircraft manufacturing process. For example, in one embodiment, the nose portion can be attached to the aircraft after all major internal and external sub-assemblies have been put together and/or after the aircraft has been painted. Accordingly, the aircraft can occupy less floor space during manufacture and can accordingly reduce the cost of manufacture.

From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made within the scope of protection defined by the appended claims.