The question of what speed the plane develops during takeoff is of interest to many passengers. Opinions of non-professionals always differ - someone mistakenly assumes that the speed is always the same for all types of a given aircraft, others correctly believe that it is different, but cannot explain why. We will try to understand this topic.
Takeoff is a process that takes the timeline from the start of the aircraft movement to its complete separation from the runway. Takeoff is possible only if one condition is met: the lift must acquire a value greater than the mass of the object taking off.
Various "interfering" factors that have to be overcome to lift the aircraft into the air (weather conditions, wind direction, limited runway, limited engine power, etc.) prompted aircraft designers to create many ways to get around them. Improved not only the design of flying vehicles, but the very process of their takeoff. Thus, several types of take-off were developed:
- From brakes. The acceleration of the aircraft begins only after the engines have reached the set thrust mode, and until then the aircraft is held in place by means of the brakes;
- Simple classic takeoff, assuming a gradual increase in engine thrust while the aircraft is moving along the runway;
- Aids take off. Typical for aircraft carrying combat service on aircraft carriers. The limited runway distance is compensated by the use of ramps, ejection devices, or even additional rocket motors installed on the aircraft;
- Vertical take-off. It is possible if the aircraft has vertical thrust engines (for example, the domestic Yak-38). Such devices, similar to helicopters, first gain altitude from a place vertically or during acceleration from a very short distance, and then smoothly transition into horizontal flight.
Consider the takeoff phase of a Boeing 737 turbofan aircraft as an example.
Takeoff of the Boeing 737-800
Passenger Boeing 737 take off
Almost every civil aircraft takes off according to the classical scheme, i.e. the engine picks up the required thrust directly in the very process of takeoff. It looks like this:
- The aircraft starts moving after the engine reaches about 800 rpm. The pilot gradually releases the brakes while keeping the control stick neutral. The takeoff run begins on three wheels;
- To begin liftoff, the Boeing must acquire a speed of about 180 km / h. When this value is reached, the pilot smoothly pulls the handle, which leads to deflection of the flaps and, as a result, to the nose of the apparatus. Then the plane accelerates on two wheels;
- With the nose up on two wheels, the aircraft continues to accelerate until the speed reaches 220 km / h. When this value is reached, the airplane takes off from the ground.
Take-off speed of other typical aircraft
- Airbus A380 - 269 km / h;
- Boeing 747 - 270 km / h;
- Il 96 - 250 km / h;
- Tu 154M - 210 km / h;
- Yak 40 - 180 km / h.
The given speed is not always sufficient for a lift-off. In situations where strong winds are blowing in the direction of takeoff, a high ground speed is required. Or, conversely, with a headwind, a lower speed is sufficient.