Weight and Lift

747-400 Facts Length: 232 feet (~ 71 meters) Height: 63 feet (~ 19 meters) Wingspan: 211 feet (~ 64 meters) Wing area: 5,650 square feet (~ 525 square meters) Max. takeoff weight: 870,000 pounds (~ 394,625 kilograms) Max. landing weight: 630,000 pounds (~ 285,763 kilograms) (explains why planes may need to dump fuel for emergency landings) Engines: four turbofan engines, 57,000 pounds of thrust each Fuel capacity: up to 57,000 gallons (~ 215,768 liters) Max. range: 7,200 nautical miles Cruising speed: 490 knots Takeoff distance: 10,500 feet (~ 3,200 meters)

Weight
This one is the easiest. Every object on earth has weight (including air). A 747 can weigh up to 870,000 pounds (that's 435 tons!) and still manage to get off the runway. (See the table below for more 747 specs.)

Lift
Lift is the aerodynamic force that holds an airplane in the air, and is probably the trickiest of the four aerodynamic forces to explain without using a lot of math. On airplanes, most of the lift required to keep the plane aloft is created by the wings (although some is created by other parts of the structure).

A principal concept in aerodynamics is the idea that air is a fluid. Let's investigate that concept more closely.