Classifications of Aircrafts

Aeronautical Techniques Engineering Assist lecturer: Ali H. Mutib rd Aircraft Engines 3 Class Classifications of Aircrafts 1.1Introduction. An aircraft may be defined as a vehicle which is able to fly by being supported by the air, or in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or dynamic lift. Although rockets and missiles also travel through the atmosphere, most are not considered aircraft because they use rocket thrust instead of aerodynamics as the primary means of lift. A cruise missile has to be considered as an aircraft because it relies on a lifting wing or fuselage/body, (Fig. 1.1). Based on method of lift, aircrafts may be classified as either lighter than air (AEROSTATS) or heavier than air (AERODYNES) (Fig. 1.2). Figure (1-1): Rocket and cruise missile Figure (1-2): Classifications of aircrafts 1 Aeronautical Techniques Engineering Assist lecturer: Ali H. Mutib rd Aircraft Engines 3 Class 1.2 Aerostats Aerostats use buoyancy to float in the air in much the same way that ships float on the water. They are characterized by one or more large gasbags or canopies, filled with a relatively low density gas such as helium, hydrogen or hot air, which is less dense than the surrounding air; Figure (1-3). Aerostats may be further subdivided into powered and unpowered types. Unpowered types are : 1- Kite which was invented in China 500 B.C. 2- Sky lanterns (small hot air balloons; second type of aircraft to fly as invented 300 B.C.), 3- Balloons 4- Blimps. Kite Sky lanterns Balloons Blimps Figure (1-3): Unpowered aerostats 2 Aeronautical Techniques Engineering Assist lecturer: Ali H. Mutib rd Aircraft Engines 3 Class A powered aerostat mostly denoted as airship or dirigible can be steered and propelled through the air using rudders and propellers or other thrust. The main types of airship are 1. Non-rigid airships: (sometimes denoted blimps) are small airships without internal skeletons. 2. Semi-rigid airships: slightly larger and have some form of internal support such as a fixed keel. 3. Rigid airships: larger with full skeletons such as Zeppelin. Although airships are no longer used for passenger transport, they are still used for other purposes such as advertising, sightseeing, surveillance, and research. As demonstrated in Fig. 1.4. Figure (1-5): Non-rigid airship (blimp) Figure (1-6): Rigid airship Figure (1-4): Powered aerostats 3 Aeronautical Techniques Engineering Assist lecturer: Ali H. Mutib rd Aircraft Engines 3 Class 1.3 Aerodynes Aerodynes, or heavier than air vehicles, resemble almost all types of aircrafts. It pushes air or gas in one direction, so that a reaction occurs (by Newton’s laws of motion) that pushes the aircraft in the other direction. There are four groups of aerodynes, namely:- Fixed wing aircrafts. Rotorcrafts. Hybrid fixed/rotary wing. Fourth group relying upon other methods for generating lift. 1. Fixed wing aircraft :generally denoted as airplane or aeroplane, aerodynamic lift is generated by forward movement of wings, Figure (1-7), and can be divided into Powered like airplane. Unpowered like gliders and sailplanes. Figure (1-7): Powered and Unpowered Fixed wing aircraft 2. Rotorcraft: generally denoted as rotary wing aircraft, lift is generated by spinning wing shaped rotors (sometimes called rotary wings) Figure (1-8), and can be divided into Powered like helicopters. Unpowered like auto-gyro. Figure (1-8): Powered and Unpowered rotary wing aircraft. 4 Aeronautical Techniques Engineering Assist lecturer: Ali H. Mutib rd Aircraft Engines 3 Class 3. Hybrid fixed/rotary wing aircrafts is sometimes identified as compound rotorcraft and may include additional thrust engines or propellers and static lifting surfaces. This group has several types, namely, Tilt-wing: tilt-wing aircraft features a wing that is horizontal for conventional forward flight and rotates up for vertical takeoff and landing. Tilt-wing aircraft are typically fully of VTOL operations. Figure (1-9): Tilt-wing aircrafts. Tilt rotor: represents a compound rotorcraft and vectored thrust .Examples for tilt-rotor are Ospery V-22. Figure (1-10): Tilt-rotor aircrafts. 5 Aeronautical Techniques Engineering Assist lecturer: Ali H. Mutib rd Aircraft Engines 3 Class Mono tilt rotor: A mono tilt-rotor aircraft combines the vertical lift capability and structural efficiency of a helicopter with the speed and range of an airplane. Figure (1-11): Mono tilt rotor. Mono-tilt-rotor rotary-ring: A mono-tilt-rotor rotary-ring VTOL aircraft is currently under development. It differs from previous tilt-rotors in that instead of each rotor consisting of long blades attached to a central rotary ring; it has a single rotary ring which has a diameter equal to the entire wingspan of the aircraft, with the ring being attached to the tips of the wings. Figure (1-12): Mono-tilt-rotor rotary-ring aircrafts. 6 Aeronautical Techniques Engineering Assist lecturer: Ali H. Mutib rd Aircraft Engines 3 Class Coleopter: is a type of vertical take-off and landing aircraft design where the fuselage is surrounded by an annular wing. The aircraft is intended to take off and land on its tail. SNECMA Coleopter machine may have been the first of this type of aircraft to actually be constructed; the approach itself was first put forward in Germany late in World War II. Figure (1-13): Coleopter aircrafts. 4. The fourth group may be subdivided into three groups, namely: Lifting body: a lifting body is an aircraft configuration in which the body itself produces lift. A lifting body is a fuselage that generates lift without the shape of a typical thin and flat wing structure. Lifting bodies generally minimize the drag and structure of a wing for very high supersonic or hypersonic flight or spacecraft re- entry. Figure (1-14): Martin-Marietta X-24. The X-24 was one of a group of lifting bodies flown by the NASA to demonstrate the ability of pilots to maneuver and safely land wingless vehicles designed to fly back to Earth from space and be landed like an airplane at a predetermined site. 7 Aeronautical Techniques Engineering Assist lecturer: Ali H. Mutib rd Aircraft Engines 3 Class Flapping-Wing (Ornithopter):- Flapping wing or ornithopter is an aircraft that flies by flapping its wings similar to the flight of birds, bats, and insects. Though machines may differ in form, they are usually built on the same scale as these flying creatures. Figure (1-15): UTIAS ornithopter no.1 flapping-wing aircrafts. Fan Wing: - The FanWing is a recent innovation (starting 2005 in United Kingdom) and represents a completely new class of aircraft. It uses a fixed wing with a cylindrical fan mounted spanwise just above the wing. As the fan spins, it creates airflow backwards over the upper surface of the wing creating lift. Specifications A prototype was tested in 2007. It was airborne after a ground roll of just 1 m and had a flight speed of 29 km/h and endurance of 80 min. Its maximum take-off weight was 12 kg and powered by a 1.2 kW electric motor. Figure (1-16): FanWing aircraft 8 .

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