Patent Application
20230060580
Field of the Invention: This invention relates generally to commercial aircraft. More specifically, the invention is directed to the conversion of passenger aircraft to cargo aircraft and facilitating the carriage of increased main deck payload.
Description of Related Art: There are many passenger aircraft that for various reasons sit parked and unused at locations around the world. In contrast, there is a substantial need for commercial cargo aircraft. However, the cost of a new cargo aircraft is substantial and may not be an economically viable option for many cargo carriers.
One option for cargo carriers is to pay for the aircraft manufacturers conversion centers to convert a passenger aircraft to a cargo aircraft. Unfortunately, aircraft manufacturers and passenger-to-cargo conversion companies charge large fees for this conversion. For example, the conversion cost for a modern wide-body aircraft may be on the order of $30 Million or more.
Accordingly, it would be an advantage over the prior art to provide a system and method for conversion of passenger aircraft to cargo aircraft at a substantially reduced cost. It would be a further advantage if the conversion method also minimized the alterations that are made during conversion to keep the conversion costs as low as possible while still meeting the needs of a cargo aircraft.
The present invention is a system and method for modifying a passenger aircraft and converting it for use as a cargo aircraft, wherein the steps include removing all structures that were previously put into the aircraft to accommodate passengers including walls, storage, and seating, wherein the seat tracks are left in the floor to function as secure attachment points, moving pallet sections into the aircraft that can fit through the existing doorways, and assembling the pallet sections together to create pallet assemblies, wherein the pallet assemblies function as a bridging system upon which cargo loads may be disposed without causing damage to the existing unreinforced floor of the aircraft, wherein each of the pallet assemblies is connected to the existing seat tracks in the floor in order to secure the pallet assemblies to the aircraft frame.
In a first aspect of the invention, multiple pallet sections are disposed a together using a plurality of channels, wherein the channels are secured to the pallet sections and to the seat tracks of the aircraft.
In a second aspect of the invention, top mount anchor fittings or seat tracks are disposed on a top surface of the pallet assemblies to provide a plurality of anchor points for securing loads to the pallet assemblies and to the aircraft structure.
In a third aspect of the invention, the existing aircraft doors may be increased in height or altered in order to accommodate larger loads within the aircraft or to facilitate the loading of cargo.
These and other embodiments of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in combination with the accompanying drawings.
Reference will now be made to the drawings in which the various embodiments of the present invention will be discussed so as to enable one skilled in the art to make and use the invention. It is to be understood that the following description illustrates embodiments of the present invention and should not be viewed as narrowing the claims which follow.
There may be substantial differences between a passenger aircraft and a cargo aircraft. These differences include structural differences that make an aircraft suitable for passengers but not suitable for high cargo loads and their required restraint systems. For example, access to a passenger aircraft is typically provided through a relatively small doorway. In contrast, cargo aircraft typically have a larger doorway that enables larger loads to be moved in and out of the aircraft more conveniently.
Another relevant structural difference may be attributed to the load bearing capacity of the pressurized compartment within an aircraft. While cargo loads are typically heavier than passengers for a given amount of floor space, passenger aircraft are not configured for handling the larger or distributed loads of cargo because passengers and their seats are typically lighter or confined to a smaller footprint.
In summary, commercial passenger aircraft are typically designed and certified to carry a particular type of load that may be defined as point loads and density through the seat tracks and into the aircraft structure. Point loads of passenger aircraft may therefor create a load limitation because of the inherent design, which is primarily based on the requirements of, but not limited to, passenger seats, passengers, and various lightweight cabin structures.
The present invention introduces a supplementary structure that can be readily installed, removed, and quickly reconfigured in a converted passenger aircraft to enhance the load carrying capability and configuration options of a cargo aircraft.
The prior art describes the cost of the conversion by aircraft manufacturers. One of the reasons for the high cost is that to increase the load carrying capability required for the carriage of heavier freight loads, it is common to modify the pre-existing passenger aircraft structure to strengthen the affected cargo carrying areas. However, this typically requires a permanent and costly modification to the aircraft structure. Accordingly, one of the advantageous aspects of the present invention is the ability to convert passenger aircraft to cargo aircraft in a manner that does not require costly modification of existing aircraft structure.
Thus, the first embodiment of the invention requires fewer and less expensive modifications to a passenger aircraft. The first step in the process of conversion in the first embodiment of the invention is to remove a substantial portion of the existing structure that is typically present in the passenger compartment of a passenger aircraft. The extent to which the structure is removed may depend upon the specific requirements of the customer. While most of the structure is removed, there may be some structure that is left in place, such as selected lavatories.
More specifically, the structural items removed include but are not limited to, overhead luggage bins, kitchen galleys, lavatories, closets, carpet, cabin monuments, and all of the passenger seating from the proposed cargo compartment. Other items may include flooring materials that have been put down over the basic floor structure of the passenger compartment, and an inner wall of the aircraft. In the first embodiment, insulation disposed between the inner wall and an outer wall of the aircraft is left intact.
Importantly and advantageously, one item that is not removed or substantially modified from the proposed cargo compartment are the seat tracks. Seat track is commonly installed on the floor of the passenger compartment allowing passenger seats and other cabin monuments to be attached to the seat track rather than directly to the floor beams, panels or other aircraft structure. This allows for secure attachment of the seats and other cabin monuments, providing the option of moving or removing these items quickly and simply by removing them from the seat tracks as needed. Seat tracks are typically anchored directly or indirectly to the structure of the aircraft and thus form inherently strong attachment points and are a structural load carrying element of the aircraft structure (with inherent load carrying limitations).
The first embodiment of the invention removes most or all of the structures that are put into the aircraft for flight attendants to use when taking care of passengers. However, pilot seating will remain intact as may a few seats in front of a smoke barrier that may be disposed between the pilot area and the cargo area. Removed structures include storage areas for food and lockers for passenger items such as coats and other odd sized items. This may also include lavatories at various locations within the fuselage, with at least one lavatory remaining intact for pilot and crew (if any).
While obvious structural elements for passenger comfort and care are removed, other structural items that may be removed include the inner compartment walls that typically cover the insulation between the inner and outer walls. Passenger compartments may also include overhead baggage bins, ceiling structures that hide hoses for oxygen masks, ductwork used for routing air to passenger seats, and wiring for lights, in-flight entertainment systems, and various other passenger accommodation requirements.
However, some of these existing structures on the walls and in the ceiling may be left intact if they are useful for the customer and do not interfere with the installation of the pallet assemblies and cargo.
Essentially, the passenger area may be stripped bare. All modifications to the aircraft at this point are to remove all of the items that are installed to sustain passengers. This is all seating, food preparation and storage areas, general and overhead stowage, passenger and cabin crew emergency equipment, and ductwork for carrying air to all passenger areas of the aircraft. However, it should be understood that while most passenger area ductwork will be removed, some of the ductwork may just be modified for the cargo area.
It should be noted that the cockpit and any supporting structure is not removed or modified. Essentially, all that is left of the passenger compartment is a bare floor and wall framing with insulation. Passenger lavatories may also be removed, while leaving at least one lavatory for the pilots and crew near the cockpit.
It is noted that the doors 28 in the crew compartment 22 are the original doors of the aircraft 20. The doors 28 have not been modified in any way in the first embodiment of the invention.
Because of the design of some passenger aircraft, the original seat tracks 10 may not be continuous from the front of the cargo compartment all the way to the rear. In this situation, seat tracks 10 may need to be installed in order to obtain the desired continuous seat track 10 through the entire cargo compartment.
It is noted that the spacing between the seat tracks 10 may not be uniform. However, this spacing is a function of the existing seat tracks 10 in the passenger aircraft that are being converted by the present invention. However, it does not matter if the seat tracks 10 have uniform spacing or not, as the bridging system may be manufactured to match the seat tracks 10 spacing of any aircraft.
The next step in the first embodiment of the invention is to add a minimal amount of structure to the cargo compartment 18 to enable cargo that is heavier or of a different load distribution (direct load and/or for load restraint) than passengers to be supported by the existing floor. However, instead of adding permanent and expensive structural reinforcement to the floor, an important aspect of the first embodiment of the invention is to add a bridging system to compensate for any lack of reinforcement. This aspect of the invention may result in a substantial cost savings in the conversion process and complexity of the structure for operational and maintenance purposes.
It is noted that by using the existing seat tracks 10, in conjunction with the invention, the capacity for total load are increased. While the point loads are unchanged, the loads are spread over the span of seat tracks 10 that are covered by a pallet assembly. Advantageously, the bridging system is installed without making any permanent changes to the floor in the cargo compartment 18. Thus, reconfiguration of the cargo compartment 18 is as easy as moving the bridging system as will be shown.
Another aspect of the first embodiment is that additional seat tracks 10 may be installed or replaced to suit specific aircraft variances. By using existing structural hardpoints of the aircraft frame or floor beams, no modification of the frame is possible.
One of the purposes of dividing the pallet assembly 40 into multiple pallet sections 42 is to avoid having to increase the size of a door into the aircraft 20. In other words, each pallet section 42 of the pallet assembly 40 will fit through the existing door of the aircraft 20. Then the pallet sections 42 may be brought together to form a larger pallet assembly if necessary, and in a manner to be explained to form the pallet assembly 40. However, it should be understood that a pallet assembly may be comprised of a single pallet section.
One advantage of having a pallet assembly comprised of multiple pallet sections is that if any of the pallet sections are damaged, the damaged pallet section may simply be removed and replaced.
The bridging system may be comprised of any high load bearing materials. These materials include such things as metal, fiberglass, composites, plastic, some types of hardened rubber, or any other materials with suitable load bearing properties.
The pallet sections 42 may also use structural shapes that increase the load bearing strength of the high load bearing materials. For example, the pallet sections 42 may have an internal honeycomb structure using the high load bearing materials, or use various extrusions to add strength.
The bridging system may be envisioned as a frame, platform or pallet structure that is mounted on the seat tracks 10 such as shown in
The pallet assemblies 40 are shown as being close to the walls 46 of the aircraft 20, but with sufficient space between the walls 46 and the pallet assemblies 40 and the pallet assemblies themselves to enable a person or mechanism to maneuver between them. In this way, it may always be possible to secure the cargo to the pallet assemblies 40 using a cargo net and make periodic checks or adjustments as needed.
For example, the pallet assemblies 40 may secure cargo to the top surface using cargo nets (not shown). The cargo nets may be secured to the pallet assemblies 40 by using attachment points provided by the top mount seat tracks 50 disposed on the top surface 52. Use of the top mount seat tracks 50 also provides attachment points along their entire length, and thus provide maximum flexibility for the placement and securing of loads to the pallet assembly 40. In other words, the distribution of the forces on the cargo loads and the pallet assembly 40 may be balanced for a variety of different load configurations.
While the top mount seat tracks 50 are a convenient system for providing multiple attachment points for cargo nets in the first embodiment, it should be understood that any cargo attachment system may be substituted for the top mount seat tracks 50 disposed around the pallet assemblies 40.
The dotted lines on each of the pallet sections 42 indicate the attachment points 48 that are used to attach the pallet sections to the Hat channel tracks 56 on the bottom surface 54 of the pallet sections. It is noted that while the bolts 48 may be used to secure the Hat channel tracks 56 to the pallet sections 42, any adequate means of securing them may also be used. For example, these alternate securing means may be rivets or any other adequate fastening device.
This layout also shows that there is space on all four sides of the pallet assemblies 40. This access may be crucial in order to secure the loads to the pallet assemblies 40 using cargo nets that are disposed over the loads and then secured to the top mount seat tracks 50.
Not all of the pallet assemblies 40 are the exact same size and shape. In this first embodiment, three pallet assemblies 64 at the rear of the aircraft 20 are modified in shape in order to fit within the available dimensions of the narrowing cargo compartment 18. It is also noted that a wider space is left between pallet assemblies 40 near the front of the aircraft 40 where cargo doors 58 are located so that the cargo doors are not blocked.
After experimentation, it has also been determined that pallet assemblies near a front end of the cargo compartment 18 may require modification because of narrow aircraft design at the front of the aircraft 20. A modification to pallet assemblies may also be required over the wing box joint areas 68 as shown in
However, in a second embodiment of the invention, the height or other features of the door 58 may be increased or changed. This is not a temporary but a permanent structural modification to the aircraft 20 to accommodate larger objects. This is illustrated in
It is noted that an added feature of the first embodiment allows the option to not install a 9G Bulkhead as is typical in large cargo aircraft. This further reduces the price of the conversion of the aircraft. Instead of having a 9G wall, 9G individual nets are used to secure the loads for each pallet assembly 40.
In summary, the first embodiment of the present invention may be described as a method for converting a passenger aircraft to a cargo aircraft, said method comprising the steps of 1) removing structures from the aircraft that are provided for passenger use in a passenger compartment to thereby create a cargo compartment, 2) stripping all floor covering material off of a floor and exposing seat tracks that are not removed from the floor, wherein the seat tracks extend a length of the cargo compartment, 3) installing a smoke barrier between the cargo compartment and a front end of the aircraft, wherein the front end is designated as a crew compartment and includes a cockpit, 4) providing a plurality of pallet assemblies for carrying cargo, wherein the pallet assemblies are coupled to the seat tracks, wherein the pallet assemblies are spaced apart to enable access to the plurality of pallet assemblies, and 5) wherein the floor is not reinforced but keeps a same structure that was created for the passenger aircraft, and wherein the plurality of pallet assemblies distributes weight of cargo over the seat tracks.
Furthermore, the first embodiment of the present invention may also be described as a system for converting a passenger aircraft to a cargo aircraft, said system being comprised of a cargo compartment disposed at a rear portion of the cargo aircraft, a crew compartment disposed at a front portion of the cargo aircraft, wherein the crew compartment includes a cockpit, a plurality of seat tracks disposed in a floor of the cargo compartment, wherein the seat tracks are disposed in parallel to each other and extending a length of the cargo compartment, a plurality of pallet assemblies for carrying cargo, wherein the pallet assemblies are coupled to the seat tracks, wherein the pallet assemblies are spaced apart to enable access to the plurality of pallet assemblies, and wherein the floor of the cargo compartment is not reinforced but keeps a same support structure as when the cargo compartment was used as a passenger compartment.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.
| Number | Date | Country | |
|---|---|---|---|
| 63236985 | Aug 2021 | US |
