airplane

US and Canadian a heavier-than-air powered flying vehicle with fixed wings

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

What does it mean when you dream about an airplane?

Airplanes in dreams may carry the same connotations as air (e.g., ideas, intellect) or simply represent flying dreams. Particularly if one is the pilot, an airplane may represent one’s body, freedom, the power to “rise above” a situation, soaring to new heights, or even escape from everyday concerns.

airplane

[′er‚plān]

(aerospace engineering)

A heavier-than-air vehicle designed to use the pressures created by its motion through the air to lift and transport useful loads.

Airplane

A heavier-than-air vehicle designed to use the pressures created by its motion through the air to lift and transport useful loads. To achieve practical, controllable flight, an airplane must consist of a source of thrust for propulsion, a geometric arrangement to produce lift, and a control system capable of maneuvering the vehicle within prescribed limits. Further, to be satisfactory, the vehicle should display stable characteristics, so that if it is disturbed from an equilibrium condition, forces and moments are created which return it to its original condition without necessitating corrective action on the part of the pilot. Efficient design will minimize the aerodynamic drag, thereby reducing the propulsive thrust required for a given flight condition, and will maximize the lifting capability per pound of airframe and engine weight, thereby increasing the useful, or transportable, load. See Airframe, Flight controls

airplane

A power-driven, heavier-than-air aircraft that derives its lift in flight chiefly from aerodynamic reactions on surfaces, which remain fixed under given conditions of flight. It excludes gliders and rotor planes but includes VTOLs (vertical takeoff and landing) and convertiplanes.

Airplane

(dreams)

We received an interesting amount of mail about dreams containing planes and plane crashes. It appears that people often dream about being in a plane crash, witnessing a crash, or being bombed or shot at from planes. Airplanes, like all other vehicles, symbolize a portion of your life’s journey. The part of your life that is represented is usually a memory, material from your unconscious mind, or something that is physically far away from you. Since we use planes to travel to places that are far away, the logical progression of this interpretation is that the airplane is symbolic of an event, individuals, or emotions that are either in the past, physically apart from you, or deep in the unconscious and far from conscious thought. Disturbing dreams in which you are being bombed or where you see a bloody crash scene may be trying to bring up issues and feelings that have been buried in the unconscious mind (from the past or the present) but are still powerful and disturbing to you. The more powerful, vivid, and disturbing this dream is, the greater the necessity to interpret and obtain a satisfactory meaning.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Airplane

a heavier-than-air aircraft for flights in the atmosphere using engines and, usually, fixed wings. Because of its high speed, carrying capacity, effective range, operational reliability, and maneuverability, the airplane has become the most widely used type of aircraft. It is used to transport passengers and cargo and for military and special purposes. (See AVIATION for the historical development of the airplane and basic information.)

Classification. According to function, airplanes are classified as civil or military. Civil airplanes include transports (passenger, cargo-passenger, and cargo airplanes); sports airplanes; airplanes for setting speed, rate-of-climb, altitude, range, and other records; commuter, executive, training, agricultural, and special-purpose airplanes (such as rescue airplanes and remote-controlled airplanes); and experimental airplanes. Military airplanes are designed to destroy airborne and ground or naval targets or to carry out other combat missions. They are subdivided into fighter-bombers, bombers, and reconnaissance, transport, liaison, and ambulance airplanes. (SeeAIR FORCE, FIGHTER AVIATION, FIGHTER-BOMBER AVIATION. BOMBER AVIATION, RECONNAISSANCE AVIATION, and MILITARY TRANSPORT AVIATION.)

External features are the basis for the classification of airplanes according to design. Such features include the number and position of wings and engines and the shape and position of the empennage. Figure 1 illustrates the principal types of airplanes. Depending on the number of wings, a distinction is

Figure 1. Principal types of airplanes

made between monoplanes—airplanes with a single wing—and biplanes—airplanes with two wings positioned one above the other. Biplanes with one wing shorter than the other are called sesquiplanes. Biplanes are more maneuverable than monoplanes, but they have greater drag, which reduces the flying speed. Most modern airplanes therefore use the monoplane design.

Depending on the position of the wing with respect to the fuselage, airplanes are classified as low-wing, midwing, or high-wing.

Depending on the position of the empennage, a distinction is made between airplanes of the classical design, where the empennage is located behind the wing, airplanes with a “canard” configuration, where the horizontal control surfaces are located in front of the wing, and “tailless” airplanes, where the control surfaces are incorporated into the wing. The classical design may feature a single fin, multiple fins, or a V-shaped empennage.

Depending on the type of landing gear, airplanes are classified as land-based airplanes, seaplanes, or amphibians (seaplanes equipped with wheeled landing gear).

Depending on the type of engines, airplanes are classified as piston-engine, turboprop, or turbojet airplanes.

Depending on flying speed, airplanes are classified as subsonic (with a speed corresponding to a Mach number M < 1), supersonic (5 > M≥ 1), or hypersonic (M≥ 5).

Aerodynamics. Aerodynamic force R arises as a result of the action of the air flow on the wing (see AERODYNAMIC FORCE AND MOMENT). The vertical component of this force with respect to the flow is called lift Y, and the horizontal component is called drag Q (seeAERODYNAMIC DRAG). The drag is the sum of the forces of air friction against the surface of the wing Q_fr and the pressure of the air flow Q_pre (which are combined in a quantity called the profile drag Q_pro = Q_fr + Q_pre) together with the induced drag Q_ind, which arises when lift is present on the wing. Induced drag is caused by the formation of air vortices at the ends of the wing as a result of the flow of air from the region of positive pressure below the wing to the region of negative pressure above it. At a flying speed close to the speed of sound, wave drag Q_w may arise. The lift of an airplane is usually equal to the lift of the wing, and the drag is equal to the sum of the resistances of the fuselage, empennage, and other parts of the airplane over which the airstream flows, together with the interference drag g_int (the mutual influence of these parts). The lift-to-drag ratio K = Y/Q is an important characteristic of airplanes; the maximum value of the ratio for modern airplanes reaches 10–20.

Engine installation. The power plant of an airplane consists of aircraft engines and various systems and devices, such as propellers, fire-fighting equipment, and the fuel, induction, starting, lubrication, and thrust control systems. In selecting the point of installation of engines and the number and type of engines, it is necessary to take into account the aerodynamic drag produced by the engines, the rotational moment that arises if one of the engines fails, the complexity of the layout of the air intakes, the possibility of servicing and replacing engines, the noise level in the passenger compartment, and other factors.

Design. The basic parts of an airplane are the wing, fuselage, landing gear, and empennage. The general layout of an I1–62 turbojet passenger airplane is illustrated in Figure 2.

The wing creates lift as the airplane moves. It is usually rigidly fixed to the fuselage but can sometimes be rotated with respect to the lateral axis of the airplane, as in vertical takeoff and landing aircraft, or its configuration (sweep and span) can change. Roll control surfaces (ailerons) and high-lift devices are mounted on the wing. The fuselage houses the crew, passengers, cargo, and equipment, and structurally connects the wing, empennage, and sometimes the landing gear and power plant. The landing gear is used for takeoff and landing and for taxiing on the airfield. Wheeled landing gear, floats (on seaplanes), skis, and caterpillar tracks (on airplanes with cross-country capabilities) may be installed on airplanes. The landing gear may be retractable in flight or fixed. An airplane with retractable landing gear has lower drag but is heavier and more complex in design. The empennage provides stability, control, and balance for the airplane.

Control systems and equipment. The control systems of an air plane are divided into the primary and auxiliary systems. The control systems for the control surfaces are commonly listed as primary systems. The auxiliary systems are used to control the

Figure 2. 11–62 turbojet: (1) nose gear, (2) crew cabin, (3) entry door, (4) fuselage, (5) forward passenger compartment, (6) main landing gear, (7) wing, (8) engines, (9) equipment compartment, (10) stabilizer, (11) antenna, (12) fin, (13) rear passenger compartment, (14) galley, (15) wardrobe

engines, trim tabs, landing gear, brakes, hatches, and doors. The airplane is controlled by means of a control column or stick, pedals, switches, and other devices located in the crew cabin. Automatic pilots and on-board computers may be included in the control system to facilitate piloting and increase flight safety; dual-type controls are used. The loads acting on the controls when control surfaces are operated are reduced by hydraulic, pneumatic, or electrical amplifiers called boosters and by servomechanisms. If the control surfaces prove ineffective, for example, during flight in very thin atmosphere or on vertical takeoff and landing aircraft, control is accomplished by means of gas vanes.

The equipment of an airplane includes instrumentation, radio and electrical equipment, deicers, high-altitude and special-purpose equipment, and cabin furnishings. Additional equipment for military airplanes includes armament, such as cannon, rockets, and aerial bombs, and armor. Depending on the function, instrumentation is classified as flight-control and navigational equipment, including variometers, artificial horizons, compasses, and automatic pilots, equipment for monitoring engine operation, such as pressure and fuel consumption gauges, and auxiliary equipment, such as ammeters and voltmeters. The electrical equipment provides for the operation of instruments, control equipment, radios, the engine starting system, and lighting. The radio equipment includes radio communication, radio navigation, and radar equipment and automatic takeoff and landing systems. The high-altitude equipment, including air-conditioning and oxygen supply systems, is used to protect and ensure the safety of passengers and crew during flight at high altitudes. Cabin furnishings provide convenience and comfort for the passengers and crew. The special equipment includes systems that provide automatic monitoring of the operation of equipment and aircraft structures, aerial photography systems, and equipment for transporting the sick and wounded.

Vertical takeoff and landing (VTOL) and short takeoff and landing (STOL) aircraft. An increase in the flying speeds of airplanes results in an increase in takeoff and landing speeds. Consequently, the lengths of runways can reach several kilometers. STOL and VTOL aircraft are being developed in connection with this trend. STOL aircraft feature high cruising speeds (600–800 km/hr) and a takeoff and landing distance no greater than 600–650 m. The reduction in takeoff and landing distance is achieved primarily by using powerful high-lift devices, by controlling the boundary layer, by using acceleration assists during takeoff and speed-reducing devices during landing, and by deflecting the thrust vector of the main engines. In VTOL aircraft, vertical takeoffs and landings are accomplished by using special lift engines, by deflecting the jet nozzles, or by rotating the main engines, which are generally turbojets. Typical configurations for VTOL aircraft are illustrated in Figure 3.

Figure 3. Vertical takeoff and landing aircraft

REFERENCES

Palenyi, E. G. Oborudovanie samoletov. Moscow, 1968.
Kurochkin, F. P. Osnovy proektirovaniia samoletov s vertikal’nym vzletom i posadkoi. Moscow, 1970.
Shul’zhenko, M. N. Konstruktsiia samoletov, 3rd ed. Moscow, 1971.
Nikitin, G. A., and E. A. Bakanov. Osnovy aviatsii. Moscow, 1972.
Proektirovanie samoletov, 2nd ed. Moscow, 1972.
Sheinin, V. M., and V. I. Kozlovskii. Problemy proektirovaniia passazhirskikh samoletov. Moscow, 1972.
Schmidt, H. A. F. Lexikon Luftfahrt. Berlin, 1971.
Jane’s All the World’s Aircraft. London, 1909—.

G. A. NIKITIN and E. A. BAKANOV