Flight Vehicle is a type of transportation device which capable of traveling in the air/atmosphere or to the outer space. In simple words, all transportation devices that flies are considered flight vehicle. It includes the simple hot air balloon, the conventional airliner, fighter aircraft, rockets, and even the sophisticated space shuttle.
Nowadays, there are a lot of flight vehicles operated. Each has their own unique characteristic from the other and can be easily distinguished from the others, while several may look very similar but completely different. In order to distinguish one with another and to make one easier to studies a specific type, classification has been made for the flight vehicle based on several characteristics, such as region of operations, the source of the lifting force, etc. Here are several classifications of flight vehicle along with a brief description for each class of flight vehicle.
Flight Vehicle Classification based on Its Operation Domain
Aircraft is a type of flight vehicle that operates inside Earth’s atmosphere. As it operates inside Earth’s atmosphere, aircraft always operates under the influence of Earth gravity field and Earth’s atmosphere field, which causes the aircraft to experience Earth’s gravitational pull (weight) and aerostatic/aerodynamic forces in their operation. Thus, in order fly, an aircraft needs to generate lift force equal to its weight (by using aerostatic forces, aerodynamic forces or propulsion’s reaction force). Aircraft is also usually shaped in streamline in order to minimize drag forces.
Spacecraft is a type of flight vehicle that operates outside Earth’s atmosphere. Since it operates outside Earth atmoshpere, spacecraft no longer experience aerostatic/aerodynamics force, hence, a spacecraft is not required to have a streamlined shape (although some spacecraft is designed with streamlined shape because some of their region of operation is inside Earth’s atmosphere). In the outer space, a spacecraft is influenced by the gravity field of all space objects, such as planets, satelite, and stars, although the effect may become negligible after a certain distance. These gravity field is usually being used by the spacecraft to accelerate or decelerate without its propulsion system. Aside from the space obects’ gravity field, a spacecraft is also influenced by other environment such as electromagnetic field (from sun or other stars).
Flight Vehicle Classification based on Its Main Source of Lifting Force
1. Airship (Aerostatic Craft)
Airship (aerostatic craft) is a type of aircraft that uses buoyant force generated from the air around it as its lifting force. An airship is usually characterized by a big air container called envelope that carries light-than-air air (such as hot gases or helium). These light-than-air air produces a buoyant force that cause an airship to fly/float on the air as if it is a foam floating on the water.
In general, there are only two types of airships, which are hot air balloon and zeppelin. The difference between hot air balloon and zeppelin lies on their propulsion system. Hot air balloon does not have any propulsion system and relies on wind to move, while zeppelin usually has piston powered propeller as its propulsion. Zeppelin also has an empenage its rear section to maintain its stability.
2. Airplane (Aerodynamic Craft)
Airplane (aerodynamic craft) is a type of aircraft that uses aerodynamics force generated by moving airplane’s wing relative to the wind as its lifting force. An airplane is usually characterized by a long span object called wings. These so-called wings are designed with a certain cross-section shape called airfoil, causing wings to generate aerodynamic lift force if it moves relative to the wind.
In general, airplane can be classified again based on the relative movement between airplane’s wing and fuselage. The classification consists of fixed-wing airplane, rotary-wing airplane, and mixed-fixed-rotary-wing airplane.
a. Fixed Wing Airplane
Fixed wing airplane is an airplane with one or more pairs wing commonly attached simmetrically to the left and right side of its fuselage permanently, thus not allowing wing any relative movement to the fuselage. In order to generate its lift, fixed wing airplane generate wing’s relative movement to the wind by moving the whole airplane forward. As the consequence, a fixed wing airplane must keep moving forward with a minimum velocity called stall speed so that the airplane’s wing can generate enough lift force to counteract aircraft’s weight and fly.
b. Rotary Wing Airplane
Rotary wing airplaneis an airplane with a pair of wing and its wing axis commonly attached to the upper section of its fuselage, thus allowing the wing to rotate around its axes and move relative to the fuselage. These rotating wing is commonly called rotor. By rotating its rotor, rotary wing airplane is capable of generating wing’s relative movement to the wind without the needs to move the whole airplane. Consequently, rotary wing airplane is capable of vertical take-off and hovering in the air.
c. Mixed Fixed-Rotary Airplane
Mixed fixed-rotary airplane is an airplane with certain configuration that allows it to act as fixed wing airplane or rotary wing airplane at certain condition.
3. Surface-Effect Craft
Surface-effect craft or ground effect craft is a type of aircraft that use aerodynamics force enhanced with surface effect as its lifting force. Similar to airplane (aerodynamic craft), surface-effect craft is also characterized by a long span object called wings (although its wing planform differs from the one commonly used in the airplane). Surface-effect craft’s wings are also designed with certain cross-section shape (airfoils) that will generate aerodynamic lift force when it moves relative to the wind. However, surface-effect craft’s wings are placed very close to the ground/sea surface so that it experience surface effect that enhances surface-effect craft’s aerodynamics. Thus, surface-effect craft commonly flies very close to the ground/sea surface.
4. Rocket (Propulsion-Lifted Craft)
Rocket (propulsion-lifted craft) is a type of aircraft that uses reaction force from its propulsion system as its lifting forces. A rocket is characterized by its long cylindrical shaped body with a conical shape at its front end and a nozzle at its rear end that exerts very hot fluids at extreme speed. As the reaction of the hot fluids exertion, the rockets experience forward reaction force (as stated in the third law of Newton) which is used to lifting force that counteracts rocket’s weight and flies the rocket itself.
Flight Vehicle Classification based on Its Operator
1. Manned Aerial Vehicle
Manned aerial vehicle is a type of flight vehicle that is operated by humans (pilots and/or crews) inside the aerial vehicle itself.
2. Unmanned Aerial Vehicle (UAV)
Unmanned aerial vehicle is a type of flight vehicle that is operated automatically by artificial intellegences inside the aerial vehicle or remotely by humans outside the aerial vehicle.