Some secrets of flying a passenger plane
Aircraft - an aircraft designed to fly in the atmosphere with the help of a thrust propulsion system and a wing, which is stationary relative to other parts of the apparatus, creating lift. A fixed wing distinguishes an airplane from a flywheel (ornithopter) and a helicopter, and the presence of an engine from a glider. An airplane differs from an airship and a balloon in that it uses an aerodynamic rather than aerostatic way to create lift.
The word "airplane" was used to designate aircraft in the 19th century. So, in 1857, captain 1st rank N. M. Sokovnin used this word to mean a controlled balloon. In a sense close to modern, the word “airplane” was first used by journalist and writer Arkady Vasilievich Ewald in the article “Ballooning”, which was published in 1863 in the newspaper “Voice”, where he first proposed the idea of such an aircraft in Russia.
Everyone who at least once flew a passenger plane was probably interested in what was happening now and what it was for. We will try to answer some of the questions.
It often happens that the first to sit up are those who are sitting in the front of the cabin, and then those who are sitting in the tail. And this is not a whim of the airline - otherwise the plane may simply 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, on the IL-62, to prevent rollover, an additional tail support was provided, and even, moreover, a balancing water tank in front of the aircraft.
However, the rear engine has its advantages. Firstly, 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 prone to "sucking" foreign objects from the runway. And finally, if one of the engines fails, the aircraft will maintain better controllability - due to its smaller “shoulder” it deploys less. At the same time, 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 fall into the vortex track of the wing, which is fraught with loss of control. Therefore, in modern aircraft engines try to place under the wings. This gives serious advantages - easy access to the engines facilitates their maintenance, and due to the even distribution of the load, the wing structure can be simplified and simplified.
Passengers are seated and fastened, the plane is taxiing to the beginning of the runway, and the pilots receive permission to take off. Look through the window: the “fluffy” wing makes an unforgettable impression, although it is not a sight for the faint of heart. Extended wing mechanization changes its profile, increasing lift and shortening the take-off run. Almost immediately after the earth goes down, a low rumble is distinctly audible: the landing gear retracts inside the fuselage or wings. But first you need to stop the heavy wheels, which still rotate after taking off from the ground: the gyroscopic effect creates a big load on the chassis cleaning mechanism. Then the plane slightly “draws down”. But you don’t need to be scared - this happens at the moment when the retractable elements of the wing mechanization are folding. This reduces the lifting force of the wing and its resistance, which allows to achieve high speeds.
During the climb, passengers lay their ears. The pressure outside falls, and without an oxygen mask already at an altitude of more than 5-6 km (and flights of modern airliners take place at altitudes of about 9-11 km), a person experiences oxygen starvation, high-altitude decompression and is unable to survive. Therefore, the cabin is relatively tight, but still you need to constantly "blow it". The pressure in the cabin is less than “at sea level” (but not lower than 0.75 atm., This corresponds to an air pressure of 2400 m above sea level), and that’s why when passengers climb (and drop in pressure) they put their ears in .
Why is it impossible to make life easier for passengers and maintain pressure corresponding to sea level? This is due to the strength of the fuselage materials. One of the first passenger aircraft with a pressurized cabin - De Havilland Comet - was inflated to almost normal atmospheric pressure. However, after a while a series of unexplained accidents followed - 4 aircraft literally fell apart in the air. One of them fell into the Mediterranean Sea, and when rescuers lifted the debris from the bottom, it turned out that the largest fragment was only about half a meter in size. Studies have shown that all these disasters occurred due to the "fatigue" of the metal: stresses arising from the pressure difference inside and outside the fuselage accumulate and can eventually destroy the aircraft.
However, progress does not stand still, and the newer the aircraft, the more advanced materials are used in it and the closer the pressure in the cabin to normal. And in the new Boeing 787, in the design of which high-strength composite materials are widely used, the pressure is promised to be maintained at "sea level" throughout the flight.
Finally, “fasten your seatbelts” signs go off and the plane goes into horizontal flight - the safest part of the trip. It's time to get out of 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 dumped at all. They enter the tank, from which they are already pumped out on the ground by a special sewage machine. Therefore, the frame from the film “The Incredible Adventures of Italians in Russia”, when a passport thrown into the toilet, sticks outside to the porthole, is just a fiction of the screenwriter.
Of course, you can’t even “go outside.” Ordinary doors through which landing and disembarkation take place are blocked in flight. And the emergency exit doors that open inward are reliably held by the pressure difference.
Management in horizontal flight, as a rule, manages the autopilot. And indeed, the manual piloting mode for modern aircraft is extremely uncharacteristic. However, calling it “manual” will also not be entirely accurate. The last (aviators do not like the word "last") Russian plane with real manual control was the Il-62: there mechanical traction control went through the entire plane. Subsequently, the control became remote, using hydraulics, but the linear relationship (i.e. direct proportionality) between the angle of deviation of the helm and the angle of deviation of the control planes was preserved. In this case, the pilot himself decides how much to turn the helm in order to, say, tilt the plane to one or another angle. The latest generation aircraft no longer have the helm as such - just a joystick, the slope of which sets the deflection angle of the aircraft itself, and all the intermediate calculations are performed by the computer.
Fasten your seat belts again, and the plane begins to descend. According to statistics, landing is the most dangerous stage of flight. The lights of the airfield are already visible ... The plane slows down, the wing mechanization elements are put forward to maintain lift - in general, everything is just like on take-off, only in the reverse order. A soft rumble, the plane begins to shake lightly - this landing gear creates instability of the flow around.
Together with the chassis, the headlights extend and automatically light up (usually they are mounted on the struts of the chassis). It would seem, why does an airplane need headlights? Aviators jokingly answer this question this way: “So that the pilot sees where to fly!” And although, of course, the headlights are used for landing and taxiing, in fact their main task is to scare away the birds. If a bird enters the engine, the latter is likely to fail, and this may even cause the plane to crash. Therefore, birds are a serious danger: according to ICAO (International Civil Aviation Organization), collisions of birds with airplanes cause damage of about $ 1 billion annually. Therefore, there is an uncompromising struggle with birds: airborne equipment is installed, special ornithological services are engaged in shooting, at some airports (for example, in Domodedovo) they even use specially trained hunting birds. White “commas” painted on cocoons (fairings) of engine fans serve the same purpose. When rotated, they create a frightening “blinking” effect: birds take it for the eyes of a predator (as well as the headlights).
In addition to the headlights, the aircraft carries aeronautical lights - to indicate the flight path and prevent dangerous proximity with other aircraft: on the right wing - green, on the left - red, and on the keel - white. It’s easy to remember such an arrangement - the pilots joke that there is a mnemonic rule: “A green co-pilot sits to the right of an experienced commander.” In addition, red or white flashing lights are located on the fuselage and wings. And recently, airlines began to illuminate the keel of an airplane when approaching - firstly, visibility is improved (for other planes), and secondly, there is no advertising.
And finally, the wheels touch the strip. A light haze at the first moment accompanies their transition from rest to rapid rotation. At this point, passengers usually applaud. However, it is 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. Anyway, aviators are superstitious people, and it is hardly appropriate to show any emotions before the flight is completed (it is better to thank the flight attendants when leaving the plane). By the way, applause may be superfluous for one more reason: when landing, the pilot may not participate at all at all! Modern airliners allow fully automatic landing at zero visibility and automatic taxiing to the terminal (at airports of category IIIC according to ICAO standards). True, there are no such airports in Russia yet. Determining who landed the plane is quite simple. A very soft landing is a characteristic sign of manual control: the pilot gently “grinds” the plane to the ground. Automatic landing is tougher because the autopilot just has to keep within the tolerances of maximum vertical speed.
To slow down, the aircraft is equipped with several systems at once. The first is air brakes - aerodynamic shields that the aircraft “fluffs” to increase drag. The second is the reverse of the engines (although, for example, it is not on the Yak-42). The third system is the actual wheel brakes. However, there were more exotic options: on some older aircraft (for example, the Tu-134 of the first series) even brake parachutes were used.
Wheel brakes on old passenger planes are shoe brakes (motorists would call them drum), and on new ones - disc brakes (on the newest models even wheels made of composite materials are used, as in Formula 1), with a hydraulic drive. Moreover, the chassis is mandatory equipped with anti-lock braking system ABS. Actually, this system came to the car from aviation - for an airplane, uneven braking is fraught with skidding and leaving the landing strip.