Narrow-Body, Single-Aisle Aircraft

Figure 6.5 shows a typical seating arrangement for single-aisle, narrow-body air­craft carrying up to about 220 passengers (all economy class). Section 6.3.1 lists the general considerations regarding doors, fineness ratio, closure angles, seat and aisle dimensions, internal facilities, and so forth for each type.

Table 6.1 provides typical dimensions for establishing narrow-body fuselage widths. All dimensions are in inches. Figure 3.50 defines the symbols used. Addi­tional fuselage interior details follow. Figure 6.5 shows examples of seating arrange­ments from two to six passengers abreast.

Two abreast (4 to 24passengers). Two-abreast seating is the lowest arrangement. The passenger comfort level demands relatively large variations in fuselage width. The typical passenger capacity extends from 4 to 19 (e. g., Beech 1900D) and could expand to 24 passengers in an extreme derivative version.

A circular cross-section is ideal to obtain the minimum weight for a pressurized cabin; however, a circular cross-section may not always prove to be best. The air­craft fuselage diameter for two-abreast seating does not provide enough space for passengers to straighten their legs when seated; therefore, a widening of the bottom half could provide more comfort, as shown in Figure 6.7. The fuselage top is semi­circular, making headroom clearance a fallout of the design. Cabin height is on the order of 60 inches and most passengers would have to bend down during boarding. A toilet facility is preferred.

Figure 6.7. Example of configuring the fuselage for the medium comfort level (in inches)

Current regulations do not require a cabin crew for up to 19 passengers, but some operators prefer to have one crew member, who uses a folding seat secured in a suitable location. An expanded variant of 2-abreast seating can exceed 19 passen­gers, but a new high-capacity design should move into 3-abreast seating, described next. The baggage area is at the rear, which is the preferred location in smaller aircraft.

Summary. A typical two-abreast fuselage would have the following features:

Cabin Width: This consists of one seat on each side of the center aisle. To

avoid tightness of space in a smaller aircraft, seats could be slightly wider, sacrificing aisle width where there is little traffic. Typically, cabin width is between 64 and 70 inches.

Cross-Section: The fuselage cross-section is typically circular or near circular (i. e., the overall width is greater than the height). Designers must compromise their choices to maximize the sales. The bot­tom half could be opened up for better legroom. There is no payload space below the floorboards but it could be used for aircraft equipment and fuel storage. Luggage space is located in the aft fuselage.

Front/Aft Closure: See Table 4.4 for the range of dimensions.

Fuselage Length: This depends on the number of passengers and facilities pro­vided (see Figure 6.5). Add front and aft closures to the fuse­lage midsection.

Family Variants: Addition or subtraction of fuselage plugs, to a maximum of

four rows, conveniently distributed on each side of the wing, is possible. The worked-out example baseline version starts with ten passengers (see Figure 6.7).

Three abreast (24 to 50 passengers). A typical 3-abreast seating arrangement accommodates 24 to 45 passengers, but variant designs change that from 20 to 50 passengers (e. g., ERJ145). Full standing headroom is possible; for smaller designs, a floorboard recess may be required (see Figure 4.12). A floorboard recess could trip passengers when they are getting to their seat. Space below the floorboards is still not adequate for accommodating any type of payload. Generally, space for luggage in the fuselage is located in a separate compartment at the rear but in front of the aft pressure bulkhead (the luggage-compartment door is sealed).

At least 1 cabin crew member is required for up to 30 passengers. With more passengers, 2 crew members are required for up to 50 passengers. A new design with potential for growth to more than 50 passengers should start with 4-abreast seating, described next.

Summary. A typical three-abreast fuselage would have the following features:

Cabin Width: This consists of two seats in a cluster and one seat on each side

of the aisle. The aisle width could be increased to ease cabin – crew access. Cabin width is from 82 to 88 inches, depending on the customer’s demand for the comfort level.

Cross-Section: The fuselage cross-section is typically circular but follows the cabin-section contour with added wall thickness. There is no payload space below the floorboards, but it can be used for aircraft equipment and fuel storage.

Front/Aft Closure: See Table 4.4 for the range of dimensions.

Fuselage Length: This depends on the number of passengers and facilities pro­vided (see Figure 6.5). Add front and aft closures to the fuse­lage midsection.

Family Variants: Addition or subtraction of fuselage plugs, to a maximum of five

rows, conveniently distributed on each side of wing, is possible. The baseline version could start with 36 passengers and range from 24 to 50 passengers (Figure 6.5 shows the largest in the family).

Four abreast (44 to 80passengers). A typical 4-abreast seating arrangement accom­modates 44 to 80 passengers, but variant designs could change that number from 40 to 96 passengers (e. g., the Bombardier CRJ1000; the Canadair CL-600 is an executive version that accommodates 19 passengers – another example of a deriva­tive). The cabin crew increases to at least three for higher passenger loads. The increase in the fuselage diameter can provide space below the floorboards for pay­load, but it is still somewhat limited. To maximize the below-floorboard space, the fuselage height could be slightly oval, with the upper-half semicircular and the bottom half elongated to suit smaller container sizes. Figure 4.12 shows a four – abreast seating arrangement; note the facilities and luggage-compartment arrange­ment. As the fuselage radius increases, the gap between the elbowrest and the fuselage wall can be reduced to 1 inch (2.54 cm) on each side, increasing the seat width.

Summary. A typical four-abreast fuselage would have the following features:

Cabin Width: A four-abreast arrangement is two seats in a cluster on both

sides of a center aisle. Cabin width is from 100 to 106 inches depending on the customer’s demand for the comfort level. The aisle width could be increased to ease cabin-crew access and passenger traffic.

The fuselage cross-section is typically circular but can be elon­gated. It follows the cabin-section contour with added wall thickness (see Table 6.1). Full standing headroom is easily achievable. There is aft-fuselage luggage space.

See Table 4.4 for the range of dimensions.

This depends on the number of passengers and facilities pro­vided. Add front and aft closures to the fuselage midsection. Addition or subtraction of fuselage plugs, to a maximum of seven rows, conveniently distributed on each side of the wing, is possible. The baseline version could start with 60 passengers and range from 40 to 96 passengers.

Five abreast (80 to 150 passengers). A typical 5-abreast seating arrangement can accommodate 85 to 130 passengers, but variant designs could extend that number somewhat on both sides. The number of cabin crew increases with passenger capac­ity. There are not many aircraft with five-abreast seating because the increase from four abreast to six abreast better suited market demand. A prominent five-abreast design is the MD-9 series (now the Boeing 717).

The fuselage diameter widens to provide more generous space. Space below the floorboards is conspicuous to accommodate standard containers (see Section 4.7.8).

The fuselage aft closure could affect seating – that is, the last row could be reduced to four abreast. To ease cabin access, the aisle width widens to at least 20 inches plus the armrest at each side. To maximize the below-floor space, the fuselage could be slightly elongated, with the bottom half stretched to accommo­date container sizes. A separate cargo space exists at the rear fuselage in the closure area.

Summary. A typical five-abreast fuselage would have the following features:

Cabin Width: Five-abreast is seating arranged as three in a cluster on one side

of the single aisle and two in a cluster on the other side. Very little gap is required between the armrest and the cabin wall because the fuselage radius is adequate. Cabin width is from 122 to 130 inches depending on the customer’s demand for the comfort level. The aisle width could be increased to facilitate passenger and crew traffic.

Cross-Section: The fuselage cross-section is typically circular but can be elon­gated. It follows the cabin-section contour with added wall thickness (see Table 6.1). Full standing headroom is easily achievable. There is potential for aft-fuselage luggage space.

Front/Aft Closure: See Table 4.4 for the range of dimensions.

Fuselage Length: This depends on the number of passengers and facilities. Add front and aft closures to the fuselage midsection.

Family Variants: Addition or subtraction of fuselage plugs, to a maximum of

eight rows, conveniently distributed on each side of the wing, is possible. The baseline version could start with 100 passengers and range from 85 to 150 passengers.

Six abreast (120 to 230 passengers). This class of passenger capacity has the most commercial transport aircraft in operation (more than 8,000), including the Airbus 320 family and the Boeing 737 and 757 families. The Boeing 757-300 has the largest passenger capacity of 230 and the highest fineness ratio of 14.7. There is considerable flexibility in the seating arrangement to accommodate a wide range of customer demands.

Figure 6.5 shows an aircraft family of variant designs to accommodate three different passenger-loading capacities in mixed classes. A typical 6-abreast seat­ing arrangement accommodates 120 to 200 passengers, but variant designs could change that number from 100 to 230 passengers. The number of cabin crew increases accordingly. The fuselage diameter is wider to provide generous space. Space below the floorboards can accommodate standard containers (see Section 4.7.8). To maxi­mize the below-floor space, the fuselage height could be slightly elongated, with the bottom half suitable for container sizes. A separate cargo space is located at the rear fuselage.

Summary. A typical six-abreast fuselage would have the following features:

Cabin Width: Six-abreast seating is arranged as three in a cluster on both

sides of the single center aisle. Very little gap is required between the armrest and the cabin wall because the fuselage radius is adequate. Cabin width is from 138 to 145 inches, depending on the customer’s demand for the comfort level. The aisle width is increased to facilitate passenger and crew traffic.

Cross-Section: The fuselage cross-section is typically circular but can be elon­gated. It follows the cabin-section contour with added wall thickness (see Table 6.1). Full standing headroom is adequate. There is potential for aft-fuselage luggage space.

Front/Aft Closure: See Table 4.4 for the range of dimensions.

Fuselage Length: This depends on the number of passengers and facilities. Add front and aft closures to the fuselage midsection.

Family Variants: Addition or subtraction of fuselage plugs, to a maximum of

ten rows, conveniently distributed on each side of the wing, is possible. The baseline version could start with 150 passengers and range from 85 to 210 passengers. The Boeing 757 base­line starts with a higher passenger load, enabling the variant to reach 230 passengers.

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