Design
For more design details, see Boeing 747-400, 747-8, and 747SP.The Boeing 747 is a large, wide-body (two-aisle) airliner with four wing-mounted engines. The wings have a high sweep angle of 37.5 degrees for a fast, efficient cruise of Mach 0.84 to 0.88, depending on the variant. The sweep also allows the 747 to use existing hangars. Seating capacity is more than 366 with a 3–4–3 seat arrangement (a cross section of 3 seats, an aisle, 4 seats, another aisle, and 3 seats) in economy class and a 2–3–2 arrangement in first class on the main deck. The upper deck has a 3–3 seat arrangement in economy class and a 2–2 arrangement in first class.
Raised above the main deck, the cockpit creates a hump. The raised cockpit allows front loading of cargo on freight variants. The upper deck behind the cockpit provides space for a lounge or extra seating. The "stretched upper deck" became available as an option on the 747-100B variant and later as standard on the 747-300. The 747-400 cockpit roof section also has an escape hatch from which crew can exit in the event of an emergency if they cannot exit through the cabin.
The 747's maximum takeoff weight ranges from 735,000 pounds (333,400 kg) for the −100 to 970,000 lb (439,985 kg) for the −8. Its range has increased from 5,300 nautical miles (6,100 mi, 9,800 km) on the −100 to 8,000 nmi (9,200 mi, 14,815 km) on the −8I.
The 747 has multiple structural redundancy including four redundant hydraulic systems and four main landing gears with four wheels each, which provide a good spread of support on the ground and safety in case of tire blow-outs. The redundant main gear allows for landing on two opposing landing gears if the others do not function properly. In addition, the 747 has split control surfaces and was designed with sophisticated triple-slotted flaps that minimize landing speeds and allow the 747 to use standard-length runways. For transportation of spare engines, 747s can accommodate a non-functioning fifth-pod engine under the port wing of the aircraft between the inner functioning engine and the fuselage.
Read more about this topic: Boeing 747
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—Henry David Thoreau (1817–1862)
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