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Takeoff is the phase of flight in which an
aerospace Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astrona ...
vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff. For
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines. ...
that take off horizontally, this usually involves starting with a transition from moving along the ground on a
runway According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made surface (often asphalt concrete, as ...
. For balloons,
helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attribut ...
s and some specialized fixed-wing aircraft (
VTOL A vertical take-off and landing (VTOL) aircraft is one that can take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust-vectoring fixed-wi ...
aircraft such as the
Harrier Harrier may refer to: Animals * Harrier (bird), several species of birds * Harrier (dog) Media * Harrier Comics, a defunct British publisher * Space Harrier, a video game series Military * Harrier jump jet, an overview of the Harrier family: ...
and the Bell Boeing V22 Osprey), no runway is needed.


Horizontal


Power settings

For light aircraft, usually full power is used during takeoff. Large transport category (airliner) aircraft may use a reduced power for takeoff, where less than full power is applied in order to prolong engine life, reduce maintenance costs and reduce noise emissions. In some emergency cases, the power used can then be increased to increase the aircraft's performance. Before takeoff, the engines, particularly piston engines, are routinely run up at high power to check for engine-related problems. The aircraft is permitted to accelerate to rotation speed (often referred to as Vr). The term '' rotation'' is used because the aircraft pivots around the axis of its main landing gear while still on the ground, usually because of gentle manipulation of the flight controls to make or facilitate this change in aircraft attitude (once proper air displacement occurs under / over the wings, an aircraft will lift off on its own; controls are to ease that in). The nose is raised to a nominal 5 °–15° nose up pitch attitude to increase lift from the wings and effect liftoff. For most aircraft, attempting a takeoff without a pitch-up would require cruise speeds while still on the runway. Fixed-wing aircraft designed for high-speed operation (such as commercial jet aircraft) have difficulty generating enough lift at the low speeds encountered during takeoff. These are therefore fitted with high-lift devices, often including slats and usually flaps, which increase the camber and often area of the wing, making it more effective at low speed, thus creating more lift. These are deployed from the wing before takeoff, and retracted during the climb. They can also be deployed at other times, such as before landing.


Required speeds

The ''takeoff speed required'' varies with aircraft weight and aircraft configuration (flap or slat position, as applicable), and is provided to the flight crew as indicated airspeed. Operations with transport category aircraft employ the concept of the takeoff V-speeds: V1, VR and V2. These speeds are determined not only by the above factors affecting takeoff performance, but also by the length and slope of the runway and any peculiar conditions, such as obstacles off the end of the runway. Below V1, in case of critical failures, the takeoff should be aborted; above V1 the pilot continues the takeoff and returns for landing. After the co-pilot calls V1, they will call VR or "rotate," marking speed at which to rotate the aircraft. The VR for transport category aircraft is calculated such as to allow the aircraft to reach the regulatory screen height at V2 with one engine failed. Then, V2 (the safe takeoff speed) is called. This speed must be maintained after an engine failure to meet performance targets for rate of climb and angle of climb. In a single-engine or light twin-engine aircraft, the pilot calculates the length of runway required to take off and clear any obstacles, to ensure sufficient runway to use for takeoff. A safety margin can be added to provide the option to stop on the runway in case of a rejected takeoff. In most such aircraft, any engine failure results in a rejected takeoff as a matter of course, since even overrunning the end of the runway is preferable to lifting off with insufficient power to maintain flight. If an obstacle needs to be cleared, the pilot climbs at the speed for maximum climb angle (Vx), which results in the greatest altitude gain per unit of horizontal distance travelled. If no obstacle needs to be cleared, or after an obstacle is cleared, the pilot can accelerate to the best rate of climb speed (Vy), where the aircraft will gain the most altitude in the least amount of time. Generally speaking, Vx is a lower speed than Vy, and requires a higher pitch attitude to achieve. The speeds needed for takeoff are relative to the motion of the air ( indicated airspeed). A headwind will reduce the ground speed needed for takeoff, as there is a greater flow of air over the wings. Typical takeoff air speeds for jetliners are in the range of . Light aircraft, such as a Cessna 150, take off at around .
Ultralight Ultralight aviation (called microlight aviation in some countries) is the flying of lightweight, 1- or 2-seat fixed-wing aircraft. Some countries differentiate between weight-shift control and conventional three-axis control aircraft with aile ...
s have even lower takeoff speeds. For a given aircraft, the takeoff speed is usually dependent on the aircraft weight; the heavier the weight, the greater the speed needed. Some aircraft are specifically designed for short takeoff and landing (STOL), which they achieve by becoming airborne at very low speeds.


Assistance

Assisted takeoff is any system for helping
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines. ...
into the air (as opposed to strictly under its own power). The reason it might be needed is due to the aircraft's weight exceeding the normal maximum takeoff weight, insufficient power, or the available
runway According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made surface (often asphalt concrete, as ...
length may be insufficient, or a hot and high airfield, or a combination of all four factors. Assisted takeoff is also required for gliders, which do not have an engine and so are unable to take off by themselves. Hence assisted takeoff is required.


Vertical

Vertical takeoff refers to aircraft or rockets that take off in a vertical trajectory. Vertical takeoff eliminates the need for airfields. Most vertical take off aircraft are also able to land horizontally, but there were certain rocket-powered aircraft of the ''
Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German '' Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the '' Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabt ...
'' that only took off vertically, landing in other ways. The Bachem Ba 349 ''Natter'' landed under a parachute after having taken off vertically. Other late projects developed in
Nazi Germany Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...
, such as the Heinkel P.1077 ''Julia'' or the Focke-Wulf ''Volksjäger'' 2, climbed to their ceiling at a nearly vertical angle and landed later on a skid.


VTOL

Vertical take-off and landing (VTOL)
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines. ...
include
fixed-wing aircraft A fixed-wing aircraft is a heavier-than-air Aircraft, flying machine, such as an airplane, which is capable of flight using wings that generate Lift (force), lift caused by the aircraft's forward airspeed and the wing configuration, shape of ...
that can hover, take off and land vertically as well as
helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attribut ...
s and other aircraft with powered rotors, such as
tiltrotor A tiltrotor is an aircraft which generates lift and propulsion by way of one or more powered rotors (sometimes called ''proprotors'') mounted on rotating shafts or nacelles usually at the ends of a fixed wing. Almost all tiltrotors use a t ...
s."Straight Up - A History of Vertical Flight," Steve Markman and Bill Holder, Schiffer Publishing, 2000. Some VTOL aircraft can operate in other modes as well, such as CTOL (conventional take-off and landing),
STOL A short takeoff and landing (STOL) aircraft is a conventional fixed-wing aircraft that has short runway requirements for takeoff and landing. Many STOL-designed aircraft also feature various arrangements for use on airstrips with harsh conditio ...
(short take-off and landing), and/or
STOVL A short take-off and vertical landing aircraft (STOVL aircraft) is a fixed-wing aircraft that is able to take off from a short runway (or take off vertically if it does not have a heavy payload) and land vertically (i.e. with no runway). The ...
(short take-off and vertical landing). Others, such as some helicopters, can only operate by VTOL, due to the aircraft lacking landing gear that can handle horizontal motion. VTOL is a subset of
V/STOL A vertical and/or short take-off and landing (V/STOL) aircraft is an airplane able to take-off or land vertically or on short runways. Vertical takeoff and landing (VTOL) aircraft are a subset of V/STOL craft that do not require runways at a ...
(vertical and/or short take-off and landing). Besides the helicopter, there are two types of VTOL aircraft in military service: craft using a
tiltrotor A tiltrotor is an aircraft which generates lift and propulsion by way of one or more powered rotors (sometimes called ''proprotors'') mounted on rotating shafts or nacelles usually at the ends of a fixed wing. Almost all tiltrotors use a t ...
, such as the Bell
Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and ...
V-22 Osprey, and some aircraft using directed jet thrust such as the Harrier family.


Rocket launch

The takeoff phase of the flight of a
rocket A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entire ...
is called "rocket launch". Launches for orbital spaceflights, or launches into interplanetary space, are usually from a fixed location on the ground, but may also be from a floating platform such as the San Marco platform, or the Sea Launch launch vessel.


See also

* Balanced field takeoff * Climb (aeronautics) * Cruise (aeronautics) * Descent (aeronautics) * Landing * V speeds


References

{{Flight phases Flight phases Articles containing video clips * Aircraft performance