The air flow from the wing of this agricultural plane is made visible by a technique that uses colored smoke rising from the ground. The swirl at the wingtip traces the aircraft's wake vortex, which exerts a powerful influence on the flow field behind the plane.
is a branch of dynamics
concerned with studying the motion of air, particularly when it interacts with a moving object. Understanding the motion of air (often called a flow field) around an object enables the calculation of forces and moments acting on the object. Typical properties calculated for a flow field include velocity
as a function of position and time. By defining a control volume
around the flow field, equations for the conservation of mass, momentum, and energy can be defined and used to solve for the properties. The use of aerodynamics through mathematical analysis, empirical approximation and wind tunnel experimentation form the scientific basis for heavier-than-air flight
External aerodynamics is the study of flow around solid objects of various shapes. Evaluating the lift and drag on an airplane, the shock waves that form in front of the nose of a rocket is an example of external aerodynamics. Internal aerodynamics is the study of flow through passages in solid objects. For instance, internal aerodynamics encompasses the study of the airflow through a jet engine.
The ratio of the problem's characteristic flow speed to the speed of sound comprises a second classification of aerodynamic problems. A problem is called subsonic if all the speeds in the problem are less than the speed of sound, transonic if speeds both below and above the speed of sound are present (normally when the characteristic speed is approximately the speed of sound), supersonic when the characteristic flow speed is greater than the speed of sound, and hypersonic when the flow speed is much greater than the speed of sound. Aerodynamicists disagree over the precise definition of hypersonic flow; minimum Mach numbers for hypersonic flow range from 3 to 12. Most aerodynamicists use numbers between 5 and 8. (Full article...)
The Boeing 777 is a long-range, wide-body twin-engine jet airliner manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet and is commonly referred to as the "Triple Seven". The aircraft has seating for over 300 passengers and has a range from 5,235 to 9,380 nautical miles (9,695 to 17,372 km) depending on model. Its distinguishing features include the largest diameter turbofan engines of any aircraft, six wheels on each main landing gear, a circular fuselage cross-section, and blade-shaped tail cone. Developed in consultation with eight major airlines, the 777 was designed to replace older wide-body airliners and bridge the capacity difference between the 767 and 747. As Boeing's first fly-by-wire airliner, it has computer mediated controls; it is also the first entirely computer-designed commercial aircraft.
The 777 is produced in two fuselage lengths. The original 777-200 model first entered service in 1995, followed by the extended range 777-200ER in 1997; the stretched 777-300, which is 33.3 ft (10.1 m) longer, began service in 1998. The longer-range 777-300ER and 777-200LR variants entered service in 2004 and 2006, respectively, while a freighter version, the 777F, debuted in 2008. Both longer-range versions and the freighter feature General Electric GE90 engines, as well as extended and raked wingtips. Other models are equipped with either the GE90, Pratt & Whitney PW4000, or Rolls-Royce Trent 800 engines. The 777-200LR ranks as the world's longest-range airliner and holds the record for longest distance flown by an unrefuelled commercial aircraft, with the demonstrated capability to fly more than halfway around the world.
United Airlines first placed the 777 into commercial airline service in 1995. As of October 2009, 56 customers have placed orders for 1,116 aircraft of all variants, with 822 delivered. The most common variant used worldwide is the 777-200ER, with 412 aircraft delivered, and Emirates operates the largest 777 fleet, with 78 aircraft. The airliner has had one hull-loss accident, with no passenger fatalities, attributed to a Trent 800 engine fuel component as of October 2009.
Through the 2000s, the 777 has emerged as one of its manufacturer's best-selling models. Because of rising fuel costs, airlines have acquired the type as a comparatively fuel-efficient alternative to other wide-body jets and have increasingly used the aircraft on long-haul, transoceanic routes. Direct market competitors include the Airbus A330-300 and the A340, with the upcoming A350 XWB and Boeing 787 programs currently in development.
- Span: 212 ft 7 in (64.8 m)
- Length: 242 ft 4 in (73.9 m)
- Height: 61 ft 5 in (18.7 m)
- Engines: 2 X GE 90-115B
- Cruising speed: 0.84 Mach (555 mph, 892 km/h, 481 kn) at 35,000 ft (11,000 m) cruise altitude
- First flight: 12 June 1994
- Number built: 649 as of August 2007