Abstract:
A less-than-200-seat-class passenger airplane includes a passenger cabin with two longitudinal aisles, and at least six economy class seats abreast the cabin. The cross-section of the cabin perpendicular to a longitudinal axis of the airplane fuselage has a horizontal diameter value in excess of a vertical diameter value.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to airplanes and, more specifically, to passenger airplane configurations. 
     BACKGROUND OF THE INVENTION 
     Current “small” commercial airplanes such as the Boeing 737 and 717, the Airbus A320 family, and regional jets in the less-than-100-seat class being designed by Bombardier, Embraer and Fairchild Dornier, all feature a passenger cabin with a single-aisle. A single-aisle configuration used in current airplanes in these smaller classes minimizes drag, weight, fuel bum, and economic penalties. However, the single-aisle fails to provide spacious cabins, desirable ambiance and interior architecture, and easy mobility in flight for both passengers and cabin crew. As a result, the passenger appeal of single-aisle aircraft is significantly less than that of larger twin-aisle aircraft. 
     Current larger commercial airplanes such as the Boeing 747, 767, and 777, and the Airbus A340 family feature a passenger cabin with a twin-aisle. A twin-aisle configuration used in current airplanes in these larger classes provides increased passenger comfort over a single-aisle configuration. 
     Due to economic and performance constraints, small aircraft currently known in the art are limited to single-aisle configurations at the expense of increased passenger comfort, such as that available in twin-aisle configurations. Therefore, there exists a need to improve passenger comfort in small commercial aircraft while minimizing drag, weight penalties, fuel burn, and economic penalties. 
     SUMMARY OF THE INVENTION 
     The present invention provides a twin-aisle small airplane. The airplane of the present invention provides the passenger comfort of a twin-aisle configuration that is usually only provided by airplanes in larger classes. At the same time, the airplane of the present invention minimizes drag, weight penalties, fuel burn, and economic penalties. 
     A less-than-200-seat-class passenger airplane includes a passenger cabin with two longitudinal aisles, and at least six economy class seats abreast the cabin. The cross-section of the cabin perpendicular to a longitudinal axis of the airplane fuselage has a horizontal diameter value in excess of a vertical diameter value. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
     FIG. 1 is a cross-section view of an airplane formed in accordance with the present invention; 
     FIGS. 2 and 3 are x-ray top views of the airplane shown in FIG. 1; 
     FIG. 4 is an x-ray top view of the airplane from FIG. 1 showing cargo compartments; 
     FIG. 5 is a side view of the airplane from FIG. 1; 
     FIGS. 6 and 7 are cross section front views of the airplane from FIG. 1; 
     FIG. 8 is a cross-section front view of an airplane formed in accordance with an alternate embodiment of the present invention; and 
     FIG. 9 illustrates an alternate embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides a twin-aisle cabin interior in an efficient configuration of a small airplane  18 . As shown in FIG. 1, a horizontal oval fuselage  20  is implemented in a small airplane configuration. Shown in FIG. 1 is a cabin deck  22  that separates a passenger cabin  24  from a cargo compartment  26  defined by sidewalls  28  and a floor  30 . The passenger cabin  24  preferably accommodates seven economy seats abreast in a 2-3-2 arrangement (outboard groups of two seats  40 , and an inboard group of three seats  42 ) with two aisles  38  separating the groups. Other embodiments may have six seats abreast in a 2-2-2 configuration, or eight abreast in 2-4-2 configuration. In one embodiment the seat bottom width is 18.5 inches (777 comfort level) and aisle widths are 19 inches. Head, shoulder, armrest, and foot level clearances from outboard seat centerline to the cabin sidewall also meet typical payload criteria for an outboard seat passenger. Air ducts  50  are located at the top of the fuselage  20  above central stowage bins  48  that are located above the inboard group of seats  42 . Outboard stowage bins  46  are positioned above the respective outboard groups of seats  40 . The cargo compartment  26  is sized to receive containerized cargo called Unit Load Devices (ULDs), such as LD3-46 containers, or “two-winged” variants of LD3-46 containers. 
     In one embodiment, the oval fuselage  20  has a width of about 201 inches and a height of about 187 inches, and uses an elliptical perimeter geometry. Somewhat different dimensions, and/or non-elliptical ovals with width exceeding height, could also be used within the spirit and scope of the invention. The perimeter of this example cross-section is 609.7 inches, and the perimeter per seat is 87.1 inches per seat. The cross-section perimeter value is virtually identical to that of a conventional single-aisle 6-abreast cross-section which also accommodates similar comfort seats and LD3-46 containers in the lower deck. The cross-sectional area of an example of a 7-abreast, twin-aisle “small” airplane according to the present invention is 206.3 sq. ft., or 29.5 sq. ft. per seat. 
     FIGS. 2 and 3 show x-ray top views of a 90-seat, dual-class, 7-abreast economy class, twin-aisle configuration of the airplane  18  shown in FIG.  1 . The fuselage  20  includes two forward passenger cabin doors  66 , two aft passenger cabin doors  64 , and emergency window exits  62  located over the wings. In another embodiment, the fuselage  20  includes an aft exit  60  located approximately on the airplane&#39;s centerline. However, the aft exit  60  could be located at other positions depending upon cabin layout. FIGS. 2 and 3 also show a representative 4-abreast twin-aisle first or Business Class seating zone at the front of the cabin, and representative galley and lavatory installations. 
     FIGS. 4 and 5 show the airplane  18  with a forward cargo door  70  located below the forward starboard passenger door  66 . The forward cargo door  70  provides access to a forward cargo compartment  72 . Also shown is an aft cargo door  78  located below the aft starboard passenger door  64 . The aft cargo door  78  provides access to an aft cargo compartment  80 . FIG. 5 shows the airplane  18  with a bulk cargo hold door  86  located aft of the passenger cabin  24 . The bulk cargo hold door  86  provides access to a bulk cargo hold. Copending U.S. patent application Ser. No. (pending), attorney docket no. BOEI-1-1015, filed Oct. 2, 2001, hereby incorporated by reference, discloses cargo-loading means suitable for the airplane configuration described above. 
     As shown in FIG. 6, an airplane  90  includes a T-tail configuration is shown for providing a greater lever arm to the horizontal tail. A low tail or other tail configuration could be used in alternate embodiments of the invention. 
     FIG. 7 shows a cross-section of an alternate fuselage  100 , which utilizes a flat underside to the fuselage cross-section. The perimeter of the fuselage  100 , with 7 seats abreast, is less than that of the fuselage shown in FIG. 1, and thus provides less room for containerized cargo below the passengers cabin. The reduced perimeter further reduces aerodynamic drag, at the cost of cargo capacity. 
     FIG. 8 shows a front view of a high-wing airplane  102  with a similar cross-section as that of the airplane  18  shown in FIG.  1 . In this embodiment, a cargo compartment  105  receives cargo containers (e.g., LD3-46) rotated sideways (90 degrees from that shown in FIG.  1 ). The cargo compartment  105  travels the full length of the lower deck without having a break for a wing box or landing gear wheel well. Main landing gear  115  retracts into fairings  120  on either side of the cargo compartment  105 . 
     In an alternate embodiment, as shown in FIG. 9, the present invention provides a section  150  of the fuselage with a substantially constant cross-section for a short distance forward of and immediately behind the wing. As a result, this airplane configuration can conveniently be “stretched” into longer body models by adding the constant cross-section sections  160  ahead of or behind the wing. Section  162  is a tail section that connects to the main section  150  or any numbered additional section  160 . A single size wing platform can accommodate fuselages with up to a certain number and size of constant cross-section fuselage sections. For example, a first wing platform accommodates bodies corresponding to 90, 105, and 120 dual-class seats. A second wing platform accommodates bodies corresponding to 135, 160, and 185 seats, and a third wing platform accommodates bodies corresponding to 210, 250, and 290 seats. In the longer body versions, structure is strengthened, more doors are provided in the constant cross-section fuselage sections, and bigger engines are used as required to meet payload-range mission requirements. Thus, this new twin-aisle “small” airplane cross-section could apply to a very large family of airplanes from around the 90 seat regional jet class all the way through the 757 and 767 “middle of the market” class. 
     While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.