Heavier than Air
This type of aircraft must have a power source to provide the thrust necessary to obtain lift. Simple heavier-than-air craft include kites. In heavier-than-air aircraft, there are two ways to produce lift: aerodynamic lift and engine lift. In the case of aerodynamic lift, the aircraft is kept in the air by wings or rotors. With engine lift, the aircraft defeats gravity by use of vertical thrust.
Examples of engine lift aircraft are rockets, and VTOL aircraft such as the Hawker-Siddeley Harrier. Among aerodynamically lifted aircraft, most fall in the category of fixed-wing aircraft, where horizontal airfoils produce lift, by profiting from airflow patterns determined by Bernoulli’s equation and, to some extent, the Coanda effect.
Lighter than Air
Examples of lighter-than-air aircraft include non-steerable balloons, such as hot air balloons and gas balloons, and steerable airships (sometimes called dirigible balloons) such as blimps (that have non-rigid construction) and rigid airships that have an internal frame.
By Design
Overall, aircraft types can be divided into four classifications, as
- Single-engine, Prop-driven Aircraft: Single-engine, prop-driven aircraft are the heart and soul of general aviation. They can be broken down into two categories: high-wing and low-wing. High-wing designs, such as the Cessna 172, feature a wing that is located above the fuselage, providing low stall speeds, strong stability and good visibility below the aircraft. Low-wing designs, such as the Piper Cherokee and Mooney 301, feature a wing that is located below the fuselage, providing better aerodynamics and higher air speeds. Another distinction is the layout of the landing gear–tricycle or tail-dragger. These aircraft can also feature pressurized cabins and turboprop engines, such as the Mooney 301.
- Twin-engine, Prop-driven Aircraft: Twin-engine, prop-driven aircraft form the heart of business aviation. These aircraft vary in size from smaller models, such as the Cessna 340, to larger models, such as the Beech King Air. They can be equipped with standard engines or turbo-prop engines and can have pressurized cabins. This category also includes larger aircraft that serve as the workhorses of commuter aviation. The Bombardier Dash 8 aircraft is a popular example, carrying up to 78 passengers (400 Series).
- Jet-driven Aircraft: Jet aircraft are represented in business aviation, commercial aviation and military aviation. Business jets are generally designed with two engines and carry between six and 15 passengers. They feature high cruise speeds, high operating ceilings and extremely long ranges.
- Jet aircraft also make up the bulk of regional airlines. The Bombardier CRJ700 is a popular example, carrying up to 78 passengers with a maximum speed of 556 miles per hour, maximum ceiling of 41,000 feet and a maximum range of 2,250 miles.
- Larger jet aircraft make up the bulk of commercial aviation. Capitalizing on advances in composite materials, aircraft manufacturers are now delivering commercial aircraft that are larger, quieter and more fuel efficient than ever. For example, the soon to be released Boeing 787 Dreamliner is a long-range, wide-body, twin-engine aircraft that will carry up to 290 passengers over 9,000 miles, while using 20% less fuel than a Boeing 767 of similar size.
- Specialized Aircraft: Specialized aircraft include gliders, helicopters and V/STOL aircraft. Gliders feature long, thin wings that produce high lift-to-drag ratios, allowing them to glide great distances.
- Helicopters utilize one or two engines and provide access to areas that are unreachable by traditional aircraft. Vertical and short takeoff aircraft feature the ability to vector their thrust downward for takeoff and landing, transitioning to a standard configuration for level flight. Examples include the Harrier jet and the Bell/Boeing V-22 Osprey. The Osprey provides vertical takeoff capability, twice the speed of a helicopter and the ability to transport up to 20,000 pounds of troops or equipment.
By Propulsion
Aircraft use propulsion for their forward (or onward) motion that is to move between distant points on the ground. Some aircraft use artificial sources of propulsion, while others do not need them.
For example, many lighter-than-air aircraft use the wind for propulsion. Many heavier-than-air aircraft, however, need engines for propulsion. Therefore, attending to their method of propulsion, aircraft can be classified into two main categories: powered aircraft and unpowered aircraft.
- Unpowered aircraft: Unpowered aircraft do not use any source of artificial energy for propulsion (although many need some sort of mechanical help to become airborne1).
- Glider: Gliders glide from one place to another without the need for a source of propulsion. Gliding is a way of managing the lift produced by wings while the aircraft is falling due to the effect of gravity. Although they don’t need a source of propulsion, gliders need some source of power to become airborne in the first place, such as forward-launching from high altitude, pulling into the air on a tow-line or using a powered ‘tug’ aircraft. Gliders, hang-gliders, paragliders and rotor-kites are typical gliders.
- Drifter: Drifters use the wind as a source of propulsion, letting it push the aircraft in the general direction of travel. Balloons are the typical drifters. Balloons manage lift in order to ascend or descend to different levels in the atmosphere until they find winds propitious to their direction of travel.
- Powered aircraft: Powered aircraft use the energy provided by engines for propulsion. Many aircraft also achieve lift in the same manner
- Propeller aircraft: Propeller aircraft use propellers (i.e. engines with vertically-mounted blades) for propulsion. The blades in the propeller form a helical surface and, when spinning, “cuts” the air in front of the blades in a screwing fashion. This, in turn, generates a forward motion on the aircraft. The power from the engines is also used for controlling the speed of the aircraft, which is achieved by adjusting the propeller’s rotational speed and/or its angle of attack. Typical propeller aircraft are propeller airplanes, which also use the forward motion generated by the propeller to lift the aircraft and sustain flight. Propellers are also a common source of propulsion used by airships, autogyros and gyrodynes, which don’t need them for lifting but only for navigating.
- Jet aircraft: Jet aircraft use jet engines for propulsion2. Jet engines takes air at the front of the engines compresses it at intense pressure and release it through a narrow end at the back of the engines, thus generating a forward motion. The power from the engines is also used for controlling the speed of the aircraft. Typical jet aircraft are jet airplanes, which also use the forward motion generated by the engines to lift the aircraft and sustain flight.
- Rocket aircraft: Rocket-powered aircraft use rockets for propulsion. Rockets work with stored fluids, which are ignited and released through a narrow end at the back of the engine, thus generating a forward motion. Rockets are typically used in spacecrafts.
- Helicopter: Helicopters use rotors (i.e. engines with rotating top-mounted blades) in order to achieve both lift and onward motion (i.e., to move forward, backwards, upwards, etc).
By Usage
Classification of aircraft by use may fall into four main categories: military, civil, experimental, and model aircraft as detailed below.
- Military Aircraft
- Fighters: Fighters are small highly maneuverable aircraft designed for air-to-air combat. Today fighters are powered with turbofan engines and equipped with radar and missiles.
- Bombers: Bombers are designed to carry and drop bombs both on ground and sea targets.
- Ground-attack aircraft: These aircraft are specifically designed for attacking both stationary and moving targets on the ground. Whenever the target requires a precision that bombers cannot achieve, ground-attack aircraft are employed.
- Rescue planes: These types of planes are normally used to rescue war victims during war. They are not normally equipped with any form of weaponry. Their main function is solely to rescue victims and bring them to the nearest help point.
- Reconnaissance Plane: These were used quite often in World War II as a form of surveillance of the enemy. These planes only and main task is to monitor the enemy’s movement and activity, and also see whether it is safe for the ground troops to make a move.
- Drop off supply planes: They were widely used during WW II, as they are faster and more efficient. They drop off supplies to the ground troops. These supplies could be food, weapons, and ammunitions.
- Dropping Troops planes: Their functions are similar to those of the planes that drop off supply. The only different is that these planes carry parachute troops and the troops are often front-line soldiers that are to attack and shock enemies.
- UAV (Unmanned Aerial Vehicle): some of them are remotely guided. They also carry weapons. They are now frequently used in areas where there are many mountains, in order to reduce risks of a pilot being killed.
- Civil Aircraft
- Commercial aviation aircraft: Although there is no clear distinction between commercial and general aviation aircraft, here commercial aircraft refers to wide-body airliners used in air transport. Some of these aircraft are designed only to carry cargo.
- General aviation aircraft: This category includes a variety of aircraft such as private airplanes, business jets, gliders, fire fighters etc. Commonly found in this category are the small aircraft own by the pilot.
- Experimental Aircraft
- Experimental aircraft an experimental aircraft is one that is under development but not yet certified to be operated. Also, those aircraft used in scientific research (such as atmospheric research) can also be considered as experimental aircraft.
- Hybrid aircraft (still an experimental aircraft): These are aircraft that will close the operational gap between air and land, or air and water.
- Model Aircraft
- Model aircraft are small-size replicas of original aircraft, and can be flying or non-flying. Flying model aircraft are used to test certain flight instruments or parameters before developing the actual aircraft. Others are sold commercially for radio-control flying. Non-flying model aircraft are used for research purposes (e.g. in wind-tunnels). Non-flying replica model aircraft are also sold for marketing purposes, etc
Dimensions of Aircraft
The various parameters that define the aircraft dimensions are.
- the length (of the fuselage),
- the wingspan, and
- the height make up the overall dimensions of an aircraft
These influence the size of the hangars and the parking aprons, as well as the taxiway side clearances. The typical dimensions are given in the illustration.
