Takeoff

Source: Wikipedia, the free encyclopedia.
For other uses, see Takeoff (disambiguation).
An F/A-18 taking off from an aircraft carrier
Embraer E-175
taking off

Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff.

For

Bell Boeing V22 Osprey
), no runway is needed.

Horizontal

Power settings

For

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.

Three airliners taking off simultaneously (note similar pitch attitudes)

Fixed-wing aircraft designed for high-speed operation (such as commercial

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.

Boeing 737-800 retracting its undercarriages
during takeoff

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 (

short takeoff and landing (STOL)
, which they achieve by becoming airborne at very low speeds.

Assistance

Main article:
Assisted takeoff
Tow line and towing aircraft seen from the cockpit of a glider

Assisted takeoff is any system for helping

maximum takeoff weight, insufficient power, or the available runway 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

Takeoff of a hot air balloon

Vertical takeoff refers to aircraft or rockets that take off in a vertical

Bachem Ba 349 Natter landed under a parachute after having taken off vertically. Other late projects developed in Nazi Germany, 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.[2]

VTOL

Main article: VTOL
The Harrier jump jet, a VTOL aircraft

Vertical take-off and landing (VTOL) aircraft include fixed-wing aircraft that can hover, take off and land vertically as well as helicopters and other aircraft with powered rotors, such as tiltrotors.[3][4][5][6] Some VTOL aircraft can operate in other modes as well, such as CTOL (conventional take-off and landing), STOL (short take-off and landing), and/or STOVL (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 (vertical and/or short take-off and landing).

Besides the helicopter, there are two types of VTOL aircraft in military service: craft using a

V-22 Osprey, and some aircraft using directed jet thrust such as the Harrier family
.

Rocket launch

Main article: Space launch
Space Shuttle Columbia in the process of lifting off from the launch pad during STS-1

The takeoff phase of the flight of a

San Marco platform, or the Sea Launch
launch vessel.

See also

References

Look up takeoff or take off in Wiktionary, the free dictionary.
Wikimedia Commons has media related to Starts in aviation.
  1. ^ Scott, Jeff (4 August 2002) "Airliner Takeoff Speeds". Aerospace Web. Retrieved 12 August 2015
  2. ^ Ulrich Albrecht: Artefakte des Fanatismus; Technik und nationalsozialistische Ideologie in der Endphase des Dritten Reiches Archived 2020-04-13 at the Wayback Machine (in German)
  3. ^ "Vertical Takeoff & Landing Aircraft," John P. Campbell, The MacMillan Company, New York, 1962.
  4. ^ Rogers 1989.
  5. ^ Laskowitz, I.B. "Vertical Take-Off and Landing (VTOL) Aircraft." Annals of the New York Academy of Sciences, Vol. 107, Art. 1, 25 March 1963.
  6. ^ "Straight Up - A History of Vertical Flight," Steve Markman and Bill Holder, Schiffer Publishing, 2000.
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