An important parameter for a plane is its speed. This is the indicator that worries both aviators and dispatchers, and, above all, passengers. Ordinary people using the services of aircraft are always interested in how fast they will fly. Modern liners easily reach 600-800 km / h. And this is far from the limit. Airspace clearance rates can be either lower or much higher. In general, science has been able to make a huge leap forward over the century. For example, “Ilya Muromets” at the beginning of the XX century could stably hold only a little more than 100 km /h.
Effects of parameters on the speed of plane
The aircraft speed depends on several basic values. These are the characteristics of the aircraft, the magnitude of its aerodynamic forces and those moments that act from the outside: air density, pressure, wind force and direction. Physically speaking, the speed of an airplane is equal to the ratio of distance to time. Usually, average indicators are considered and small intervals are taken for the calculation – most often it is customary to measure the speed in meters per second, which is then easy to translate into kilometers per hour (multiplying by 3.6).
There are several types of speeds:
- track – an indicator of the movement of the aircraft relative to the earth’s surface
- true – speed relative to the air; may coincide with the track in the absence of wind
- instrumental – an indicator determined using several pressure measurements by using special tubes.
The speed of a plane, in the air mass in which it is operating, is expressed in knots (kt). One knot = 1.852 km / h (90 kt = 167 km / h; 100 kt = 185 km / h). The speed of an airplane relative to the ground (called ground speed ), by simplifying the explanation, is equal to its own speed plus or minus the speed of movement of the air mass (wind) in which it is moving according to the direction of the wind (less in front, or more in rear).
Mach (pronounced “Mac”):
The Mach number is the ratio between the speed of the airplane in a mass of air and the speed of sound in this same mass of air. Thus, “Mach 1” represents the limit between subsonic flight (less than the speed of sound) and supersonic flight (greater than the speed of sound). Mach 1 corresponds, for a high altitude flight, to 1,060 km / h. From Mach 5 we speak of hypersonic speed. Airliners generally fly at cruising speeds that are within a range of approximately Mach 0.7 to Mach 0.85 depending on the type of aircraft.
A plane flies thanks to the relative wind (the flow of air that the aircraft undergoes by its speed in relation to the mass of air in which it operates). The air thus exerts a pressure on the lower surface of the wing (under the wing) and a depression on the upper surface of the wing (above the wing). The depression on the upper surface and the pressure on the lower surface generate a force on the wing, directed upwards and slightly backwards, called lift.. It is this lift that allows the aircraft to glide, provided of course that this force is close to the weight of the aircraft. If the lift is greater than the weight, the aircraft climbs; if the lift is less than the weight, the aircraft descends; if the lift is zero, the plane falls. In normal flight, the air flow is regular on the lower surface and on the upper surface. The air streams “stick” to the wing profile. Arrived at a certain value of angle of incidence (angle formed by the wing of the airplane and the trajectory of this airplane), variable according to the characteristics of the wing and therefore according to the planes, a “detachment” occurs. of the flow of the air streams on the and that the plane falls if the pilot is not able to catch up with it.
The takeoff is the instant when the aircraft is no longer in contact with the ground. In practice, take-off includes all the actions which allow the airplane to accelerate to a speed sufficient for the lift of the wing to be greater than the weight of the device. The take-off phase ends when the airplane is at sufficient altitude and speed to be able to maneuver; it is then in the ascent configuration. The airplane on take-off accelerates, until it reaches the rotation speed (Vr) generally close to the stall speed (Vs), the pilot then pulls on the control column, the airplane rears up slightly and takes off.
On landing , which is generally the most delicate phase of flight, the phase in which the airplane passes from flight to the ground, or the airplane will take up and make contact with the ground , is called rounding. This is often the first difficult obstacle in the training of a pilot. It requires several hours of training before being mastered: precision, flexibility, estimation of the height of the aircraft in relation to the runway. The purpose of the flare is to land the aircraft on the runway with the main gear in first with a low ground speed and the lowest vertical speed possible (if the vertical speed is high, the pilot risks damaging the landing gear. landing ).
Apart from the induced effects which we are not talking about here, when the pilot tilts the control stick to the right, the airplane tilts to the right and turns to the right; when the pilot tilts the control column to the left, the aircraft tilts to the left and turns to the left. When the pilot pushes the control stick forward, the airplane nose down and when the pilot pulls the control stick, the airplane nose up. The rudder pedals (two foot-operated pedals) allow the pilot to maintain the symmetry of the air flow on each side of his aircraft.
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