What is an airplane

What is the difference between aircraft and airplane? Aircraft is the more general term, and refers to any heavier-than-air craft that is supported by its own buoyancy or by the action of air on its structures. An airplane is a heavier-than-air craft that is propelled by an engine and uses fixed aerodynamic surfaces (i.e. wings) to generate lift. So, every airplane is an aircraft, but not every aircraft is an airplane! Gliders are aircraft that are not airplanes. The Space Shuttle is definitely an aircraft, but it is not an airplane. It does not carry engines for propulsion. Helicopters are also aircraft that are not airplanes because their aerodynamic surfaces are not fixed - they rotate.

Why are there so many different types of airplanes?

The characteristic that most readily identifies the type, performance and purpose of an airplane is the shape of its wings. There are four basic wing types: straight wings, sweep wings (forward-sweep/sweepback), delta wings and the swing-wing (or variable sweep wing). Each shape allows for premium performance at different altitudes and at different speeds.

Another important discriminator between airplanes is speed. Airplanes fly at subsonic, transonic, supersonic and hypersonic speeds. These speed classifications are called the "regimes" of flight. The suffix -sonic refers to the speed of sound, which is dependent on altitude and atmospheric conditions (nominally 340 meters per second). "Mach" is a term used to specify how many times the speed of sound an aircraft is traveling. Mach 1 is one times the speed of sound. Mach 2 is twice the speed of sound, and so on. Mach numbers less than 1 are speeds less than the speed of sound.

Subsonic refers to all speeds less than Mach 1. Transonic refers to all speeds from approximately Mach .9 to Mach 1.5 - that is, the speeds at which an aircraft is going through the speed of sound or "breaking the sound barrier". Supersonic refers to all speeds greater than the speed of sound, which is the same as saying all speeds above Mach 1. Hypersonic refers to all speeds greater than Mach 5. Note that an aircraft flying at hypersonic speeds can also be said to be flying at supersonic speeds.

Every modern aircraft that is built today is built for a specific purpose. Airplanes are designed for different altitudes, different speeds, different weight-carrying capacities, and different performance. Jet fighters are relatively lightweight, highly maneuverable and very fast.

They are designed to carry a relatively small amount of weight, including fuel, which necessitates refueling on long flights. Passenger airplanes are larger, carry more weight, and can fly longer distances. However, they are less maneuverable and slower than jet fighters. Other aircraft like the SR-71, are designed to fly at very high altitudes and high speeds for very long periods of time. Every aircraft fills a particular niche in the gigantic matrix that is modern aviation.

Airplane structure

Definition: A means of air transportation that is propelled by an internal combustion, turboprop, or jet engine.

Nature and Use

Airplanes fly with the help of the laws of physics and engineering. They come in all shapes and sizes and serve different purposes. Some aircraft are used for training; others are used for transporting goods and freight. Military aircraft are used in waging warfare. Passenger airliners are used for the daily transportation of travelers. Although airplanes have different designs and functions, all airplanes share common traits. The fuselage, or body of the aircraft, carries people, cargo, and baggage. Attached to the fuselage are the wings, which provide the lift to carry the aircraft and its payload. To balance the airplane in flight, the tail, or empennage, is very important. The landing gear allows the airplane to operate on the earth’s surface. The flight controls are used to maneuver the aircraft in flight. Flaps provide additional lift and drag for takeoffs and landings

Fuselage

The primary job of the fuselage is to provide space for the flight crew and passengers. The attachment of the wings and other load-bearing structures is also an important function of the fuselage.

Wings

Wings are as varied as other parts of the airplane. They come in different shapes and sizes, depending on the aircraft’s speed and weight requirements. A slower airplane may have a rectangular wing or a tapered wing. A rectangular wing is one in which the chord line, or cross section, of the wing, remains constant from the root of the wing near the body of the aircraft to the wingtip. A tapered wing is one that becomes narrower toward the tip. High-speed aircraft, such as jet transports, airliners, or fighter aircraft, have swept-wing designs. The purpose of the swept wing is to allow the airplane to fly at higher airspeeds.

Empennage

The empennage is the tail structure of the aircraft, which includes the vertical stabilizer and rudder, along with the horizontal stabilizers and elevator. These essential components provide stability for the airplane in flight.

Landing Gear

In order to move around on the earth’s surface, all aircraft have landing gear. The most common arrangement of the landing gear is the tricycle landing gear, in which the aircraft has two main wheels that extend from either the wing or the fuselage and a third wheel that extends from the nose of the aircraft.

Flight Controls

The flight control system controls the aircraft in flight and comprises the devices that command movement of the aircraft around all three axes: longitudinal, lateral, and vertical. The elevator controls the airplane’s longitudinal movement about its lateral axis. In other words, it causes the airplane’s nose to go up or down. Finally, the rudder controls the airplane about the vertical axis.

Flaps

Airplanes have flaps for both takeoffs and landings. Located on the inboard portion of the wing at the rear, flaps change the shape of the wing in a way that creates both lift and drag. The first half of travel, after takeoff, creates more lift than drag, whereas the last half of travel, before landing, creates more drag without a noticeable increase in lift.

The Power Plant

The internal combustion engine powers many of today’s light airplanes. The most popular arrangement of the engine is in the horizontally opposed configuration. The engine is air-cooled and typically arranged in a flat four- or six-cylinder configuration, allowing the best cooling for all of the cylinders.

"Aero" is a Greek prefix signifying air. Air is made up of a mixture of gasses, and thus is itself a gas. However, in all the reading about aeronautics you have done air is referred to as a fluid. For instance, air obeys the laws of fluid dynamics. The technical definition of a fluid states that a fluid is any substance that flows. Obviously water flows, but so does air and so do powders! So, technically speaking, air and powders are fluids. Most important to our study of aeronautics is the fact that air obeys the physical laws of fluids.