How the reverse is running by the aircraft. Why reversal engines is dangerous for certain aircraft

Yes, where I work now is a contractor. And not only Boeing, but also Eirbas, Bombardia, ARZH-21, Augusta Westland, etc.

Fischer Advanced Composite Components. Abbreviated FACC.

Together with Goodrich, we cooperate with Boeing on this project and maybe we will cooperate on A350.

, posted several descriptions with pictures
I think because not everyone is connected here with aviation, it will be useful to look.
And who is connected - it is interesting to look, how it works on specifically 787

Thanks to a great deal in the form of a new model of Boeing 787 Dreamliner and information support of our Nestor's Battiki, a number of comrades are divecha in general and in a dream of B-787 in particular. I understand that LJ can read completely different people with a very different level of awareness and spheres of interest, therefore the answer to break three parts.
For those who are "in the subject"TRANSLATING SLEEVE is the back of the Motogonal with the elements of the reverse.
For beginners and those who are more interesting to know more, I will try to describe the simplest. If something is not clear - ask, and if it is written too naive, then do not judge strictly. And for those who do not need to tell about the aircraft, but it is enough to tell about the reverse, you can simply read the final part of my opus.

What is a reverse?
The landing speed of modern liners is about 200-240 km / h, which is of course much lower cruising speed, but still quite a lot for multi-torque cars. At this speed, the aerodynamic steering wheel controls is still effective and terrestrial movement control means are still very ineffective. With a sharply turned on the brake at such a speed, the aircraft will slow down, and simply "goes out" - breaks the chassis tires.

Such a situation is very dangerous for the loss of controlling the position of the aircraft, which threatens the fatal consequences (the incidence of the aircraft from the strip, damage to the fuel tanks, etc.). In order for this not happened, at speeds up to 150-180 km / h, aerodynamic means of lowering speed are used. All of them either increase the frontal resistance of the aircraft (landing panels, aerodynamic brakes, brake parachutes), or create reverse reactive traction (reverse engines), or combine these means.

In this case, we are talking about the development of a reverse for the Boeing 787 Dreamliner aircraft.
Reverse - This is a system that allows the engines to create reverse reactive traction, to brake the aircraft during the mileage by the strip.

Translating Sleeve Reverse Thrust On Boeing 787 Dreamliner. Part 3.

How does the reverse act?
In the 60-70s. The reverse is most often designed as the back of the Motogondal, in the form of two "buckets", simply overlapping the path of the jet jet jet and guide it in the opposite direction. A similar reverse was used in the design of airplanes up to the 70s (Fokker-100, B737-200, Tu-154 and An-72/74). The obvious plus is the simplicity of the design. Minus is the need to develop "television-loaded" structures, additional protection of adjacent elements (wing or fuselage trim).

In the 80s due to the appearance large number The engines with a high degree of dual-circuit, such a constructive solution finally lost its appeal. The new concept of the reverse does not imply the overlap of the first "hot" engine circuit. Overlapping only the second - "cold" contour. At the same time, the reverse system itself is now hidden inside the fairing, which significantly reduces the likelihood of damage to its unauthorized objects. Obviously, the reactive jet in this case works on the reverse not completely, but only the "second contour". However, the principle of such a reverse lies not so much in the direct effects of a reactive jet, as in the creation of a kind of airbag in the creation in front of the airbag, which greatly increases the aerodynamic resistance of the aircraft and the aircraft slowly slows down to 130 km / h. This pillow is clearly visible on photographs of landing aircraft on wet stripe. Water drops raised from concrete perfectly visualize this effect.

Translating Sleeve Reverse Thrust On Boeing 787 Dreamliner. Part 4.
How is the reverse?

Motogondol in general on modern liners consists of an air intake (INLET COWL), a fan fairing (Fan Cowl), and the rear of the Motogondel, where the second engine circuit is located and directly reversed (Reverse Thrust). The latter, as well as the fan fairing consists of two halves, capable of moving for access to the engine with operational and repair work. Under the term Translating Sleeve in this case it is understood as the outer fairing of the second circuit, which includes the outer cover and the outer cover of the second engine circuit (Outer Cowl, Outer Duct).
C-17, Tu-334 and An-148 and many other aircraft, including DreamLainer.

Directly Translating Sleeve Airplane Boeing 787 Dreamliner looks like this.

The passenger liner racing at an altitude of 10,000 meters and overcoming many hundreds of kilometers per hour should once smoothly pay off its speed to zero, frozen on the platform of the airport. Only then can be considered successful. Alas, sometimes it happens that so popular in Russia applause to pilots after touch by plane of the earth can mean premature joy. Non-standard situations after landing - Beach civil aviation.

Just the wheels of any outstanding design features of the wheels of chassis and their braking systems are not. Almost everything is in a good car: disc brakes and a system that prevents the movement of the SMOS.

Oleg Makarov

Immediately I want to make a reservation that this article does not intend to infect anyone aerophobia. Serious aviation AccidentsMoreover, with victims, instantly fall into the headlines of world news, and this is the best evidence that the air transport is a high degree of security: an airplane catastrophe is a rare event and non-ordinary. The more interesting to figure out what is happening when there is a modern aircraft with electronics, nor the high qualifications of crews do not save from situations like the one that several years ago spoiled the pre-New Year mood to the inhabitants of our country. We are talking about the death of the Tu-204 liner - the fact that December 29, 2012 could not pay off the speed after the landing, rolled out beyond the limits of the strip, struck the airfield fencing and collapsed with a partial removal of debris on the Kiev highway. Rolling out the aircraft outside the band - one of the most common causes of the air crash (i.e., airfire with human victims) Sometimes it is called the "number one killer" in civil aviation. According to IATA statistics (International Air Transport Association), approximately 24% of the dead falls on this type of incident.

Brake in the air

Before talking about the causes of these regrettable events, it is worth a little to dwell on the technical side of the question, briefly tell us about what the modern passenger liner has opportunities for timely and managed speeding. When the aircraft is in the air, there are only two main ways to reduce the speed of the liner: remove the gas by reducing the power of the engines, and increase the windshield. To solve the last task there are several specialized devices. Experienced aircraft belongs that the wing has a large number of moving parts, which (with the exception of the aileron - the roll of the roll) are combined into the concept of "wing mechanization". Dejected by different corners of the panels that are responsible for increasing the windshield (as well as a decrease in the lifting force of the wing) are called spoilers. In the domestic aviation literature, they are customary to divide the spoilers, interceptors and aileron interceptors, as a result of which confusion arises between these concepts. How we were explained in one of russian airlinesThe general term "spoilers" is more correct today, which on modern aircraft operate in three modes.

The first mode is the air brake mode (Speed \u200b\u200bBrakes). Used to reduce flight speed and / or increase vertical reduction rate. Manages this mode of the pilot, moving the steering wheel or the handle to the desired angle, while not all spoilers are deflected, but only some of them.

The second mode is a collaboration with the aileron to improve the Roll Spoiers control characteristics. The deviation occurs automatically at the corners to seven degrees with the corresponding movement of the steering wheel (control knobs) on the roll, and only external (those further from the fuselage) are deflected or only internal spoilers (it depends on the design of a particular type of aircraft).

There are no outstanding design features of the wheels of chassis and their braking systems. Almost everything is in a good car: disc brakes and a system that prevents the movement of the SMOS.

Finally, the third mode - ground braking (Ground Spoilers) - represents the greatest interest. In this mode, all spoilers are automatically deflected on the maximum angle, which leads to a sharp decrease in lifting force. After the car actually ceases to keep the air, an effective load on the brake wheels occurs and braking with the disbursement machine begins. This machine, called Antijo, is in fact no other than the anti-lock system, is functionally similar to the one that these days are installed on cars: ABS came from aviation.

Reverse? Can be without it

In addition to spoilers, the aircraft has two more speeds of velocity. First, these are already mentioned wheeled brakes. They are made on the disk scheme, and to increase wear resistance, they often use discs not from steel, but from composite materials (carbon fiber). The brakes are powered by hydraulics, although options with electric actuators have already appeared.

This aircraft did not leave the strip and is still subject to serious risk. The front rack has jammed the front rack, and the wheels are not rolling, but dirty by the strip and, erasing, burn. The main thing is that the rack does not break.

Finally, the reverse is the word, so often sounded in connection with the catastrophe in Vnukovo. In the reverse device, the portion of the reactive jet is deflected by the methods driven by hydraulics. Thus, the reactive traction no longer pushes the plane forward, but, on the contrary, it slows down. So can be a faulty reverse culprit of the catastrophe?

The answer will be more negative, because, as the practice is evidenced, the sole "culprit" of serious airframes in civil aviation does not happen at all. A catastrophe is always a bad set of several circumstances, among which both technical factors and human. The fact is that the device of reverse traction is, in fact, a system of emergency, abnormal braking.

1. The wing is reducing the wing reduces the windshield, created by the swirl with the end of the wing, and thus increases the lifting force of the wing. Different manufacturers produce endressing forms of different forms and even assign them special names: "Winglets", "Sharkers", etc. 2. Aleons relate to aerodynamic steering (driven roll) and are not part of the wing mechanization. 3. High Speed \u200b\u200bAileron. 4. The appointment of a number of gondolas located under the wing often causes questions from air passengers. Everything is simple - these are precipitators of the drives that change the position of the flaps. 5. The prejournal of the Kruger (inner forekinding) has the form of a drop-down shield. 6. The preds change the configuration of the wing in such a way as to increase the angle of the attack without breaking the aircraft. 7. The extended flaps increase the lifting force of the wing, allowing the aircraft to stay in the air at low speeds (during takeoff and landing). 8. Cloud. 9. External spoiler. 10. Internal spoiler.

Western types of aircraft, of course, are equipped with reverse devices, but are certified as if it is not. The basic requirement is presented to the energy intensity of the brakes of the main chassis racks. This means that in the absence of piloting errors and with all serviceable systems, the plane must, without resorting to the reverse, sit down on a dry strip and reveal the speed to roll up to roll on the taxi track. Moreover, due to the increased noise level when the jet rejects at all airports of the European Union, the application of the reverse is not allowed during nightly flights (23:00 - 06:00) with the exception of the poor WFP state and / or emergency situation. Modern types of aircraft can be operated both with one reverse, and in general without them, provided that there is enough WFP length, even if it is covered with precipitation. In other words, when a number of unfavorable factors contributing to turning out the aircraft outside the runway, the reverse may turn out to be latest hope For a prosperous outcome. But if he refuses him, it can hardly be considered the only reason for the airfire.

The spoiler not only increases the windshield, but also organizes the breakdown when flowing around the wing air, which leads to a decrease in the lifting force of the latter. During the flight, the spoilers are used, for example, to increase the vertical velocity of the aircraft without changing pitch. The automatic release of spoilers on the runway is provided with their "reinforcing" - translation into the Armed position prepared for release. It's like a split smoke on a rifle - if you do not weigh, then the shot will not be. The signal to the release is a combination of data from radio suitomer (height 0), compression sensors of basic racks, position ore - 0 (small gas). Unmail (mistaken or forgetfulness) spoilers are quite often featured in parsing cases associated with turning out of the strip.

Do not rush to land!

One of the main reasons for turning off the aircraft outside the runway is the so-called unstabilized approaching approach. This concept includes a flight on a preset straight at elevated speeds, with the wrong position of the wing mechanization (it comes first of all about the flaps), with a deviation from the course. Among other reasons, it is possible to name the use of wheel brakes (pilot postulate - "Do not leave the brake to the end of the strip!"). There are also cases when pilots received inaccurate data on the state of the runway and landed on a slippery strip, counting on dry.

According to domestic aerodynamic textbooks, the landing distance with the use of reverse is reduced by 25-30%, but modern types of aircraft are certified without taking into account the possibilities of the reverse. The launch of the reverse is rigidly tied to the triggering of the stroke sensor. Such a binding is caused by the bitter experience of several plane crash, the reason for which the response of the reverse in the air was. In one of these disasters, a mentally ill-sick Japanese pilot, which turned on the reverse when entering the landing was guilty.

What happens when the plane moves along the glide with an exception to the specified (usually 220 km / h) speed? Usually this means the flight, the touch of the strip in the uncountable point (especially if the plane is empty, as it was with Tu-204). It is already in itself non-standard situationwhich involves the use of all braking tools, including the reverse, the "stock" of the strip is no longer. But the danger is also the fact that the liner even after touching the band continues to move with an unsurrified high speed, and the higher the speed, the higher the lifting force of the wing. It turns out that the car does not roll along the strip, leaning on it, and actually flies, touching the strip with wheels. In this situation, there could be no chassis precipitation sensors that are in English are called a more understandable term Weight-On-Weels (Wheel Weight). Thus, from the point of view of automation, the liner continues to fly and cannot perform such purely ground operations as the inclusion of reversal or the release of spoilers in ground braking mode. And if after touching the band, the spoilers will not be released or will be removed, the disaster is almost inevitable. Moreover, with a weak clutch of wheels with a strip, antiyuza automatics will dislarge the wheels, as it would do it on a slippery surface to avoid loss of wheels. The brakes will work properly, but ... they will not slow down. Well, if the band is still really slippery, then the chances of avoiding the rolling in the one described can be considered almost zero. The consequences of rolling depend on at what speed it happens and what was on the path of the aircraft. Thus, the circumstances leading to the catastrophe can grow avalanche-like, and the failure, say, the reverse cannot have a decisive value in this situation.

The frequency with which incidents in the world occur with turning out airplanes beyond the band, one can imagine according to the analytical report prepared by the Dutch National Aerospace Laboratory in 2005. For the preparation of the report, about 400 cases were analyzed with the repayment of the world in the world for the preceding 35 years. It is easy to calculate that these are more than ten cases per year, although the study emphasized that the number of such airflowers quickly decreases: the improvement of aviation and navigation equipment is affected. Fortunately, not all these cases developed according to the worst scenario described in the article, however, and from those that ended well, were very remarkable. In 2005, a huge A340, who had a huge flight of Toronto flight from Paris, touched the strip with a flight, rolled out of the runway, partially collapsed and caught fire. Fortunately, all three hundred people on board survived.

As follows from the preliminary conclusions of the poppy, the catastrophe in Vnukovo developed for a similar scenario, and the speed of the liner during the rolling was 190 km / h, only 30 km / h less speed on which the plane was to touch landing strip. Hence the tragic finale.

There is where to strive

Incidents with rolling outside the runway happen in different countries and on different continentsBut nevertheless, some socio-geographical dependence is visible. According to research, most often, such incidents occur in Africa, followed by South and Central America, then Asia. In developed countries, such incidents happen less than one two million landings. The best thing is North America, and this is with a colossal air movement In the sky over the USA. In this, in fact, there is nothing surprising: in developing countries, more old aircraft, it is worse serviced, there are many poorly equipped airports and outdated navigation equipment, and the technological discipline is lower. All this can be said to some extent about the aviation economy of Russia, and cases of rolling, including victims, we are not so rare. But rather, to leave this company outsiders.

Yes, where I work now is a contractor. And not only Boeing, but also Eirbas, Bombardia, ARZH-21, Augusta Westland, etc.

Fischer Advanced Composite Components. Abbreviated FACC.

Together with Goodrich, we cooperate with Boeing on this project and maybe we will cooperate on A350.

Thanks to a great deal in the form of a new model of Boeing 787 Dreamliner and information support of our Nestor's Battiki, a number of comrades are divecha in general and in a dream of B-787 in particular. I understand that LJ can read completely different people with a very different level of awareness and spheres of interest, therefore the answer to break three parts.
For those who are "in the subject"TRANSLATING SLEEVE is the back of the Motogonal with the elements of the reverse.
For beginners and those who are more interesting to know more, I will try to describe the simplest. If something is not clear - ask, and if it is written too naive, then do not judge strictly. And for those who do not need to tell about the aircraft, but it is enough to tell about the reverse, you can simply read the final part of my opus.

Translating Sleeve Reverse Thrust On Boeing 787 Dreamliner. Part 3.

In the 80s in connection with the advent of a large number of engines with a high degree of dualkets, such a constructive solution finally lost its appeal. The new concept of the reverse does not imply the overlap of the first "hot" engine circuit. Overlapping only the second - "cold" contour. At the same time, the reverse system itself is now hidden inside the fairing, which significantly reduces the likelihood of damage to its unauthorized objects. Obviously, the reactive jet in this case works on the reverse not completely, but only the "second contour". However, the principle of such a reverse lies not so much in the direct effects of a reactive jet, as in the creation of a kind of airbag in the creation in front of the airbag, which greatly increases the aerodynamic resistance of the aircraft and the aircraft slowly slows down to 130 km / h. This pillow is clearly visible on photographs of landing the aircraft on the wet stripe. Water drops raised from concrete perfectly visualize this effect.

Translating Sleeve Reverse Thrust On Boeing 787 Dreamliner. Part 4.
How is the reverse?

Directly Translating Sleeve Airplane Boeing 787 Dreamliner looks like this.

The reverse is a mechanism for the direction of a piece of reactive or air jet in the direction of the aircraft movement and the creation of a reverse thrust. In addition, the reverse is called the operating mode of the aircraft engine, which will use a reversing device.

The device is used mainly after landing, on mileage or for emergency braking. In addition, the reverse is used for the movement by reverse without the help of a towing agent. Some aircraft include a reverse right in the air. Most often, the device is operated in transport and commercial aviation. After planting, the reverse is characterized by noise. It is used with a wheelchained brake system, which leads to a decrease in the load on the main brake system of the aircraft and reduces the distance, in particular with a small clutch coefficient from the runway, as well as at the very beginning of the run. The contribution of reversing thrust is very different in different situations and models of aircraft.

Jet engine

The reverse is made with the deviation of the whole or part of the jet, which comes from the engine, with the help of different shutters. In a variety of power plants, the reversing device is implemented in different ways. Special shifts are able to overlap the jet, which is created by a purely external circuit of the turbojet engine (as on A320), or jets of all contours (Tu-154m). Constructive features of the aircraft affect the equipment of the reverse. It can be both all engines and a certain part. For example, on a three-line Tu-154, the reverse can only create extreme engines, and the Yak-40 aircraft is medium.

Washing flaps - a special mechanism that redirects the air flow. There may be more than two and more on the engines. Externally, they look like buckets. For example, in an engine with a high degree of double-circuit with a flux overlapping throughout the plane as D-30KU-154 (Tu-154m).

The method of reverse, in which a special metal profile is installed in the nozzle and rear of the engine, called profiled grilles. The engine is activated on a straight line, and the rods in the lattice redirect the passage of the outgoing gases. Such a design is operated in many aircraft engines, in particular on power plants with a low degree of double-circuit with overlapping of the entire stream (Tu-154, Boeing 727).

Restrictions

But the reverse system has its drawbacks. Possible troubles include the use of reversal at low speeds (less than 140 km / h). The jet can be lifted from the surface of the WFP rubbish, which when the aircraft runs at low speeds can get into the air intake and cause damage to it. At high speeds, the raised garbage does not create interference due to the fact that he does not have time for the height of the air intake.

The reversing device is installed on four engines, but in practice the 2nd and 3rd engine reverse does not apply, because the process can damage the fuselage.

Air screw

The reverse of the screw air vessels is realized by turning the screw blades (the angle of attacking the blades is changed to the negative), namely, with the unnewable direction of rotation. Therefore, the screw creates a reverse craving. This type of reversing device is able to be used on piston and turboprop motors. Reverse is often planned on amphibians and hydrosaples.

For the first time, the application of the reverse began in the 1930s. Reversed equipped passenger planes Douglas DK-2 and Boeing 247.

Airplanes without a reversing device

A huge number of aircraft does not use the reverse on its unrequisite or technical complexity. For example, due to some abilities of the mechanization of the wing and high efficiency of air brakes in the tail of Wary 146-200, the inclusion of the reverse is not required. Accordingly, all 4 engines in reverse mode do not work. For the same reason, the Yak-42 plane does not need a reverse device.

Most aircraft With nozzles, it does not have a reverse due to the magnitude after the landing run. This circumstance is forced to build long runways, in the end of which the emergency devices should be installed for braking. Airplanes in this case are equipped with efficient wheel brakes and parachutes. It should be noted that pneumatics and brakes of such aircraft are subjected to strong wear and often require replacement.

Application reverse in the air

Part of the aircraft allows for the use of reversal thrust in the air, but this inclusion depends on the type of aircraft. In some situations, the reverse is turned on before planting, and in other - at the time of decline, which significantly reduces the vertical braking speed or makes it possible to avoid permissible speeds during dive, emergency decrease or execution of combat maneuvers.

ATR 72 is a turboprop airliner, a vivid example of using reversal in the air. In addition, the air reverse can apply the Trydent turbojet, the Concord Support Airliner, the C-17A military transport aircraft, SAAB 37 "Wiggen" fighter, Pilatus PS-6 and others.