Some secrets of flying on a passenger airplane
The aircraft is an aircraft intended for flight in the atmosphere with the help of a propulsion system that generates traction and is stationary relative to other parts of the wing device creating a lift. The fixed wing distinguishes the aircraft from the mahole (ornithoptera) and helicopter, and the presence of the engine - from the glider. From airship and balloon aircraft differs in that it uses aerodynamic rather than aerostatic way of creating lift.
The word "airplane" was used to designate aircraft in the XIX century. So, in 1857, Captain 1st Rank N. M. Sokovnin used this word to refer to a controlled balloon. In a sense close to the modern, the word "airplane" was first used by the journalist and writer Arkady Vasilievich Evald in the article "Aeronautics," which was published in 1863 in the newspaper Golos, where he first proposed the idea of such an aircraft in Russia.
Everyone who flew on a passenger plane at least once was probably wondering what is happening now and for what it's needed. We will try to answer some of the questions.
Quite often it happens that the first sit down those who sit in front of the salon, and then - those who sit in the tail. And this is not the whim of the airline - otherwise the airplane can just roll over without even leaving the terminal. This is especially important for those aircraft in which the engines are in the tail and the center of gravity is shifted far back. For example, an additional tail support was provided for IL-62 to prevent overturning, and even, moreover, a balancing water tank in the front part of the aircraft.
However, the rear location of the engines has its pluses. First, it reduces the noise level in the cabin during the flight. Secondly, such engines are higher than those located under the wings, and are less susceptible to "sucking" foreign objects from the runway. And finally, if one of the engines fails, the airplane will retain better controllability - due to a smaller "shoulder" it is less developed. However, the tail engines also have quite serious disadvantages: they are more difficult to maintain (especially in Tu-154 or MD-10 aircraft, where the engine is located directly in the fuselage). In addition, in this case, a T-shaped stabilizer is used, which, with an increase in the angle of attack, can get into the vortex trail of the wing, which is fraught with loss of control. Therefore, in modern aircraft, the engines try to place under the wings. This gives serious advantages - simple access to the engines facilitates their maintenance, and due to an even load distribution, it is possible to simplify and facilitate the design of the wing.
Passengers are seated and fastened, the plane taxiing to the beginning of the runway, and the pilots are allowed to take off. Look in the porthole: the "fluffy" wing produces an unforgettable impression, although the sight is not for the faint-hearted. The advanced mechanization of the wing changes its profile, increasing the lift and shortening the take-off length. Almost immediately after the ground drifts down, a quiet hum can be clearly heard: the chassis is retracted into the fuselage or wings. But first you need to stop the heavy wheels, which after spinning off from the ground are still spinning: the gyroscopic effect creates a big load on the mechanism of cleaning the chassis. Then the plane slightly "sits down". But it is not necessary to be frightened - it occurs at the moment when the sliding elements of the mechanization of the wing are folded. This reduces the lifting force of the wing and its resistance, which allows achieving high speeds.
At the time of climbing, the passengers lay their ears. Pressure outside falls, and without an oxygen mask already at an altitude of more than 5-6 km (and flights of modern airliners are held at altitudes of about 9-11 km), a person experiences oxygen starvation, altitude decompression and is not able to survive. Therefore, the aircraft cabin is relatively tight, but still it must be constantly "inflated". The pressure in the cabin is less than "at sea level" (but not below 0.75 atm, this corresponds to air pressure at a level of 2400 m above sea level) - and that is why, when climbing (and dropping pressure), passengers put their ears .
Why can not life be eased for passengers and maintain a sea level pressure? This is due to the strength of the materials of the fuselage. One of the first passenger aircraft with a sealed cabin - De Havilland Comet - was pressurized almost to normal atmospheric pressure. However, after a while a series of inexplicable accidents followed - 4 aircraft literally collapsed in the air. One of them fell into the Mediterranean Sea, and when the rescuers lifted the debris from the bottom, it turned out that the largest fragment measured only about half a meter. The conducted studies showed that all these catastrophes were due to the "fatigue" of the metal: the stresses arising from the difference in pressure inside and outside the fuselage accumulate and eventually destroy the aircraft.
However, progress does not stand still, and the newer the aircraft, the more sophisticated materials in it are used and the closer the pressure in the cabin to the normal. And in the new Boeing 787, in the design of which high-strength composite materials are widely used, pressure is promised to maintain at sea level throughout the flight.
Finally, the signs "fasten your seat belts" go out and the plane turns into a horizontal flight - the safest part of the trip. It's time to get up from the chair, stretch your legs, go to the toilet. By the way, we want to dispel the widespread "toilet" myth. Waste in modern airliners is not completely discharged. They enter the tank, from which already on the ground are pumped out by a special sewage machine. Therefore, a shot from the movie "The Incredible Adventures of Italians in Russia", when the passport, thrown into the toilet, sticks outside to the porthole, is just an invention of the screenwriter.
Of course, you can not "go outside." Ordinary doors, through which landing and disembarkation take place, are blocked in flight. And the emergency exit doors that open inwards are reliably held back by the pressure difference.
Management in a horizontal flight, as a rule, is headed by an autopilot. And in general the manual piloting mode for modern aircraft is extremely uncharacteristic. However, calling it "manual" will also not be exactly accurate. Extreme (aviators do not like the word "last") Russian aircraft with real manual control was IL-62: there the mechanical control rods went through the entire aircraft. Later, the control became remote, using hydraulics, but the linear relationship (ie, direct proportionality) between the angle of deflection of the steering wheel and the angle of deflection of the control planes was preserved. In this case, the pilot himself decides how much to turn the helm to, say, tilt the aircraft to one corner or another. In the aircraft of the last generation there is no steering wheel as such - only a joystick, the inclination of which is set by the angle of the deviation of the aircraft itself, and all intermediate calculations are performed by the computer.
The signs "Fasten your seat belts" and the airplane starts to decrease. According to statistics, landing is the most dangerous phase of the flight. The lights of the airfield are already visible ... The airplane reduces the speed, the elements of the mechanization of the wing are put forward to save the lifting force - in general, everything is like taking off, only in the reverse order. A quiet rumble, the plane starts to shake gently - this released chassis creates instability of flow.
Together with the chassis, the headlights are extended and automatically ignited (they are usually mounted on the landing gear rails). It would seem, why the aircraft lights? Aviators jokingly answer this question: "To the pilot saw where to fly!" And although, of course, the headlights are used for landing and taxiing, in fact, their main task - to scare away the birds. When the bird hits the engine, the latter is most likely to fail, and this can cause even an airplane crash. Therefore, birds are a serious danger: According to ICAO (International Civil Aviation Organization), bird collision with aircraft annually causes damage of about $ 1 billion. Therefore, there is an uncompromising struggle with birds at airfields: deterrent equipment is installed, special bird services are engaged in shooting, at some airports (For example, in Domodedovo) even use specially trained hunting birds. The same purpose is served by the white "commas" painted on the cocks (fairings) of the engine fans - they create a deterrent "flashing" effect when they rotate: the birds take it by the eyes of a predator (like the headlights).
In addition to the headlights, the aircraft carries air navigation lights to indicate the flight path and prevent dangerous approach to other aircraft: on the right wing - green, on the left - red, and on the keel - white. Remember this arrangement is simple - pilots joke that there is a mnemonic rule: "To the right of the experienced commander is a green co-pilot." In addition, on the fuselage and wings are located red or white flashing lights. And recently the airlines began to highlight the keel of the aircraft at the approach to landing - firstly, visibility improves (for other aircraft), and secondly, which is no advertising.
And finally, the wheels touch the strip. A light smoke at the first moment accompanies their transition from rest to rapid rotation. At this point, passengers usually applaud. However, it's too early to rejoice: the plane is still moving at a speed of about 250 km / h, and it needs to extinguish this speed before the 2-2.5-kilometer strip ends. And in general, aviators are a superstitious people, and it is hardly appropriate to show any emotions before the end of the flight (it is better to thank cabin crew when leaving the plane). By the way, applause can be superfluous for one more reason: when landing the pilot may not participate at all in management! Modern airliners allow a fully automatic landing with zero visibility and automatic tipping to the terminal (at IIIC airports according to ICAO standards). True, there are no such airports in Russia yet. Determine who planted the aircraft is quite simple. A very soft landing is a characteristic sign of manual control: the pilot gently "rubs" the aircraft to the ground. Automatic landing is more rigid, because the autopilot should simply meet the tolerances at the maximum vertical speed.
To brake, the aircraft is equipped with several systems. The first is air brakes - aerodynamic flaps, which the aircraft "razpusaet" to increase the resistance. The second is the reverse of the engines (although, for example, the Yak-42 does not have it). The third system is the wheel brakes themselves. However, there were more exotic options: on some older aircraft (for example, Tu-134 first series) even brake parachutes were used.
Wheel brakes on old passenger airplanes - kolodochnye (motorists would call them drum), and on new ones - disc (on the newest models even discs of composite materials are used, as in Formula 1), with a hydraulic drive. And the chassis is mandatory equipped with anti-lock braking system ABS. Actually, in the car this system came from aviation - for the aircraft, uneven braking is fraught with skidding and descent from the runway.