The minimum airspeed of an aircraft. How fast is the plane flying

Despite the fact that the American corporation produced the first Boeing 737 half a century ago, the aircraft is still in demand among air carriers. The liner continues to be manufactured to this day, with more than 9,500 units already produced. Aircraft of the 737th series have a narrow fuselage and are designed for flights on medium-haul routes.

Boeing 737 modifications

Behind long history liner developed and produced several modifications of the aircraft belonging to four generations.

Original

The first-generation Boeing 737 liners did not gain much commercial success, as they consumed a lot of fuel, were noisy and expensive to maintain. The last 737-100 aircraft has been out of service since 2007, and the 737-200 is still used by air carriers in Africa and some other countries.

On the basis of the Boeing 737-200, cargo and passenger-and-freight variants were created, and the 737-200 Executive Jet was produced for private owners.

Interesting! Prior to the release of the Boeing 737, a passenger aircraft was piloted by 3 people, including a flight engineer. Here, for the first time, a cockpit with two pilots was used, which became a revolutionary decision and was taken as the basis in all subsequent models of passenger liners.

classic

Despite all the improvements of the Original generation aircraft, they began to lose significantly to their competitors. New model was developed with significant changes. The aircraft received new engines, the fuselage became longer, and the number of passengers carried increased. The aerodynamics have changed, the liner was equipped with new digital avionics (on-board electronic systems).

The model 737-400, due to the enlarged cabin, changed the internal air conditioning system and added a second pair of emergency exits in the wing area.

Version 737-500 has a shortened fuselage, less capacity, but greater range.

new generation

The new generation Boeing 737 has been redesigned even more radically. The wingspan not only grew, but their geometry changed. Amendments have been made to the tail unit. The passenger cabins of New Generation aircraft and Boeing 757, 767 have much in common, since the design of the interior space of the Boeing 737 was based on design developments for these liners.

Each subsequent version of the New Generation has a greater length with a practically unchanged fuselage diameter, and the engines of the latest modification 737-900ER, thanks to an improved wing design, consume less fuel at cruising speed.

Interesting! Based on the Boeing 737-700, 737-800 and 737-900, BBJ, BBJ2 BBJ3 (Boeing Business Jet) are produced, which are the most popular in the world among private customers. On board, at the request of the customer, a bedroom, a shower room (bath), a hall for business meetings, etc., are arranged).

The layout of the passenger compartment

Device passenger cabin depends on its dimensions, which can differ significantly in various modifications. In addition, different layout options are ordered by airlines. The most common cabin option is a two-class one:

• Business Class;
• Economy class.

There are options with one economy class cabin. The total capacity ranges from 103 passengers in the 737-100 version to 220 people in the 737 MAX-9.

Business Class

The business class has soft comfortable seats with a large folding angle. The location of seats in most layout options is according to the 2-2 scheme. In total, there are from 2 to 5 rows in the bow cabin. Most often - 4 rows.

In front of the aircraft, in front of the seats, there is a kitchen for clients of the elite cabin and toilets. The quietest places are the seats of the 2nd and 3rd rows. Seats in the 1st and 4th row may not seem as comfortable due to the presence of nearby toilets, a kitchen, and in the case of the last row, a more crowded economy class. On some airlines, economy class is separated only by a curtain.

Economy class

In almost all economy class cabins, the seats are arranged according to the 3-3 pattern. Above are luggage racks. Toilets and a kitchen are located at the tail of the aircraft.

All airlines consider the seats of the first row, immediately behind the business class, to be the most comfortable in the Boeing 737. There provided more space for legs. Often tickets for this row are more expensive or sold to holders of bonus cards.

Inside the cabin, in the middle part, there is one pair of emergency exits or two, depending on the version of the liner. Seats near emergency exits also have an increased distance between the seats, but passengers can be uncomfortable with the rigid fixation of the seatbacks and side bulges on the aircraft wall. But the seats immediately behind the emergency exits recline completely and have expanded space. Row numbering is specified by the carrier.

Important: Worst Places are in the last row of the aircraft. The proximity of the bathrooms and the kitchen creates fuss and noise, and the seat backs do not fold out or recline slightly.

Design Features and Benefits

Each aircraft component has its own characteristics and associated benefits:

1. The design of the liner is a monoplane with two engines placed on pylons and swept wings.
2. Tricycle chassis have a front swivel leg. The main support is not closed by the flaps after folding is completed. This can be seen from the visible wheels. This solution simplified the design and reduced the weight of the liner, but somewhat worsened the aerodynamics.
3. Since the engines are located low, it was necessary to slightly reduce their vertical dimensions. To do this, partially lower equipment for the engine was placed on the sides and the air intake was slightly extended horizontally. The engines received a flattened shape, especially noticeable in the latest versions.
4. Winglets (wingtips) on the wings underwent changes in the course of the evolution of the Boeing 737. At first, winglets of minimal size were made on the 737-200 modification. Subsequent generations of Classic and New Generation received large endings, which are now widespread. MAX generation aircraft use twin winglets.

• Messier-Bugatti equipped the liner in 2008 with carbon brakes. This allowed to reduce the weight by 320 kg and reduce fuel consumption by about half a percent.
• The cockpit with seats for two pilots originally had analog devices and instruments. Now all aircraft are equipped with digital control systems with liquid crystal displays. Previously, there were additional windows on top of the cockpit, which improved visibility when maneuvering and made it possible to navigate through the starry sky. Later they were removed due to the installation of modern orientation devices.
• The most serious changes were made to the internal structure of the cabin. For almost every generation of liners, it was redesigned taking into account the increase in comfort and the optimal location of passenger seats.

General advantages of the Boeing 737:

• ease of takeoff, climb, landing;
• high load capacity;
• reliability and long term operation;
• low maintenance costs;
• comfortable, well-equipped interior.

Specifications

The operational and technical characteristics of the Boeing 737 have undergone the most significant changes with each new generation.

Original

new generation

History of creation

When did it start design work with the creation of the new Boeing 737 in 1964, competitors from the British Aircraft Corporation and Douglas Aircraft had already made significant progress in the production of their machines. They were ready to certify new short haul aircraft with small capacity. Boeing, in an effort to reduce the development time of the liner, took as a basis the technologies used in the production of aircraft of previous models - 707 and 727. But tests showed the unsuitability of the previous wings for new version. The newly created wing helped the aircraft fly on higher altitude by reducing the consumption of aviation kerosene.

Seats in the Boeing 737-100 were located 6 in each row, providing more seating than competing aircraft manufacturers.

Interesting! Initially, 60 passenger seats were designed inside the Boeing 737-100 cabin, but subsequently settled on the 103-seat version at the insistence of the first customer, Lufthansa.

The development program was completed quickly and without the investment of large material resources. The assembly of the first aircraft was completed in the winter of 1967. In April, the liner took to the air for the first time, and in August it made a test flight of the Boeing 737-200.

The decision to operate the aircraft with a two-pilot crew caused serious discussions and resistance from trade unions, as the unit of a flight engineer or a third pilot was reduced. However, after trials and flight tests, the company proved the possibility of using two people for piloting, and airlines were even interested in this because of the cost savings.

At the end of 1967, both versions of the new Boeing were certified, and after 2 months Lufthansa began operating the liner.

In parallel, the aircraft was being finalized so that it could land on an unpaved runway. The tests were completed successfully and the Boeing 737 immediately became in demand for flights to distant towns in the northern United States and Canada. The extended model 737-200 was in great demand and was produced until 1988.

In the 80s of the last century, the Boeing 737 was redesigned, equipped with new engines and improved cabin. The first flight of the next generation Classic aircraft took place in 1984. Subsequently, two more were added to the 737-300 modification - 737-400, 737-500.

In the 1990s, the European airliner A-320 replaced the Boeing 737 in the narrow-body segment. aircraft with technical excellence. And the airline corporation began to create a new series of modifications - New Generation. A total of 5 modifications were released - 737-600/700/800/900/900ER. Increased cruising speed, more fuel on board allowed long flights with reduced travel time. Thanks to this, the company opened up new markets.

Interesting! New Generation aircraft, except for the fuselage structure, are completely different from the first 737 liners. They have modified engines, completely new wings, and different avionics. Ideas for the interior of the cabin for passengers were even borrowed from the design of the Boeing 777.

The latest version of the NG Boeing 737-900 ER was released in 2007.

In January 2016, the Boeing 737 MAX 8 took off for its maiden flight. Aircraft of this series are designed to replace the New Generation liners.

Place of production

The geography of production of aircraft components is extensive. These are many European and Asian countries. Assembly work is carried out in the United States.

1. The fuselage for the Boeing 737 is assembled at the company's plant in Wichita, Kansas.
2. At the second stage, the aircraft body is transported to Renton (Washington State), where the final assembly is carried out. Final assembly takes approximately 2 weeks.

Operating companies

Boeing 737s are operated by world airlines in 115 countries. The largest number of liners of this type belongs to air carriers:

The aircraft is used both for transcontinental flights and for ultra-short flights. This is the main liner for flights to Alaska, to the northern regions of Canada, to the Pacific Islands.

Interesting! The shortest route operated by the Boeing 737 is 14 km. Transportation is carried out by the Japanese Japan TransOcean Air between two islands in the Pacific Ocean (Minami Daito - Kita Daito). Air Tanzania serves flights from Dar es Salaam to Zanzibar (65 km).

The cost of different models

The cost of the first generation models started at $ 49.5 million, but the price may vary depending on the configuration. Now only New Generation and MAX modifications are produced.

Development prospects

Prospects for the development of the 737 model are associated with a new generation of aircraft - MAX. Their production has already started.

Main changes and features:

1. New powerful engines have been installed. With increased power, they consume less fuel.
2. Changes have been made to the geometry of the airframe of the aircraft.
3. Chevron teeth are installed on the rear of the engines, which significantly reduce the noise of operation.
4. The cockpit will remain almost unchanged, but the interior of the passenger cabin will be produced with luggage racks and LED lighting, like the Dreamliner.

Recent improvements breathed new life in the already popular Boeing liners 737. The company's portfolio of orders is continuously replenished. Increasing comfort for passengers is added to reliability and safety.

Dear visitors of the Aviawiki site! There are so many of your questions that, unfortunately, our specialists do not always have time to answer all of them. As a reminder, we answer questions absolutely free of charge and on a first-come, first-served basis. However, you have the opportunity to get a guaranteed prompt response for a nominal amount..

Aircraft speed was, is and remains its very important factor, which allows not only to move between cities, regions or countries with great comfort, but also makes the flight time as fast as possible.

The very first civilian aircraft "Ilya Muromets" had flight speed only 105 kilometers per hour, this limit today can easily be overcome by a conventional car, and in some cases by international bus, and therefore, such a movement cannot be called comfortable.

As for the usual passenger aircraft, then their flight speed has already exceeded the milestone of 500 kilometers per hour, and is far from the limit, but as it turns out, this is far from real comfort.

Modern passenger aircraft have lost the pleasure of flying at supersonic speeds, and, moreover, this had very good reasons, consisting in the following factors:

Reliability. When flying at supersonic speeds, the aircraft is forced to have the most streamlined shape, and as you know, than more length airliner, the more difficult it is to achieve. Otherwise, the aircraft upon reaching supersonic speed can literally fall to pieces, which is naturally unsafe and can have disastrous consequences.

Profitability. In fact, supersonic aircraft have low fuel efficiency, and consequently, flights on them will be much more expensive than on slower airliners.

Narrow specialization. By this factor it should be understood that not every airport can afford to accept a supersonic airliner because of its large mass and speed, that is, a large runway is needed.

Frequent Maintenance. In view of the fact that the aircraft moves at ultra-fast speeds. It must be constantly maintained, that is, after almost every flight, check the condition of the fuselage, rivet fasteners, etc., which also causes a number of inconveniences for air carriers.

If the current speed of the aircraft civil aviation is about 800 kilometers per hour, then for supersonic passenger airliners, it was over 2100 kilometers per hour, which is more than 2.5 times faster than modern air travel. However, due primarily to safety, there are currently no operational passenger supersonic airliners, of which there are only a few in history. civil aircraft industry there were two - the Soviet Tu-144 and the Anglo-French Concorde.

It is quite possible that in the near future we will again be able to observe supersonic aircraft in the sky, and it is worth noting that a number of aircraft manufacturers and design bureaus are working on this issue. Nevertheless, one should not expect any innovations in the next few years, if only because the safety of passengers remains an important factor, and aircraft speed taken into account later.

It is known that different aircraft models have different flight speeds. Thus, combat strike aircraft have significantly higher speed indicators than civil aviation vehicles.

Speed ​​indicators of passenger airliners

Nevertheless, passenger aircraft have a low cruising and maximum speed flight, although there are exceptions to the rule. So, for example, the Concorde or Tu-144 aircraft can boast of high speed performance. More recently, the Boeing Corporation announced the creation of a new high-speed passenger vehicle, which was tentatively dubbed Zehst. The plans of the company's management and designers to bring the speed of this model to 5029 km / h.

The highest flight speeds have newer military vehicles that reach supersonic speeds.

Otherwise, the rate of climb. Depends on the model and the glide path (trajectory) set by the controller, depending on the flight conditions. Average jet liner climbs a kilometer in about a minute (about 15 m / s), and the rules for using the airspace of the Russian Federation indicate that this value should be “... 10 m / s or more”. If you are interested in how high a passenger liner can rise, we suggest reading this article.

Features of military aircraft

Fighters, attack aircraft, interceptors do not always rise from the runway. The conditions for their takeoff are often extreme. For example, it can occur from the deck of a ship, where there is no way to accelerate to the required performance.

Therefore, the military often uses additional devices, namely:

• An ejection device that launches an aircraft and gives it acceleration. When landing in a confined space, hooks are used, with which the vehicles cling to a steel brake cable stretched across the deck.
• Additional devices that create vertical traction. For example, these can be fan-type devices that form a powerful directional oncoming air movement above the deck. The result is lift.
  

  Note: The same airflow is used for landing.

The video shows the process of takeoff and landing through the eyes of pilots.

The flight of a colossus weighing several tens or hundreds of tons is a complex process. It depends on many factors, determined by the speed of the aircraft. The greater the mass and the more difficult the conditions, the greater the speed required for separation and movement. In particularly difficult conditions, auxiliary mechanisms are used. Maintaining speed is one of the factors of safe flight.

Profile at midspan

• Relative thickness (the ratio of the maximum distance between the upper and lower profile bow to the length of the wing chord) 0.1537
• Relative radius of leading edge (ratio of radius to chord length) 0.0392
• Relative curvature (the ratio of the maximum distance between the middle line of the profile and the chord to the length of the chord) 0.0028
• Trailing edge angle 14.2211 degrees

Profile at midspan

Wing profile closer to the tip

• Relative thickness 0.1256
• Relative radius of the leading edge 0.0212
• Relative curvature 0.0075
• Trailing edge angle 13.2757 degrees

Wing profile closer to the tip

End wing profile

• Relative thickness 0.1000
• Relative radius of the leading edge 0.0100
• Relative curvature 0.0145
• Trailing edge angle 11.2016 degrees

End wing profile

• Relative thickness 0.1080
• Relative radius of the leading edge 0.0117
• Relative curvature 0.0158
• Trailing edge angle 11.6657 degrees

Wing parameters

• Wing area 1135 ft² or 105.44m².
• Wingspan 94’9’’ or 28.88m (102’5’’ or 31.22m with wings)
• Wing aspect ratio 9.16
• Root chord 7.32%
• End chord 1.62%
• Wing taper 0.24
• Sweep angle 25 degrees

Auxiliary control includes wing mechanization and adjustable stabilizer.

The steering surfaces of the main control are deflected by hydraulic actuators, the operation of which is provided by two independent hydraulic systems A and B. Any of them ensures the normal operation of the main control. Steering actuators (hydraulic actuators) are included in the control wiring according to an irreversible scheme, i.e. aerodynamic loads from the steering surfaces are not transferred to the controls. Forces on the steering wheel and pedals create loading mechanisms.

In case of failure of both hydraulic systems, the elevator and ailerons are manually controlled by the pilots, and the rudder is controlled by a standby hydraulic system.

Transverse control

Transverse control

Lateral control is carried out by ailerons and spoilers deflected in flight (flight spoilers).

In the presence of hydraulic power on the steering drives of the ailerons, the lateral control works as follows:

• the movement of the control wheels of the helms along the cable wiring is transmitted to the steering drives of the ailerons and further to the ailerons;
• in addition to the ailerons, the aileron rudder drives move the spring rod (aileron spring cartridge) associated with the spoiler control system and thus set it in motion;
• The movement of the spring rod is transmitted to the gear ratio changer (spoiler ratio changer). Here, the control action decreases depending on the amount of deflection of the spoiler control handle (speed brake lever). The more the spoilers are deflected in the air brake mode, the lower the transfer coefficient of the roll movement of the steering wheels;
• further, the movement is transmitted to the spoiler mixer control mechanism, where it is added to the movement of the spoiler control handle. On a wing with aileron up, the spoilers are raised, and on the other wing, they are lowered. Thus, the functions of air brake and lateral control are simultaneously performed. The spoilers are activated when the steering wheel is turned more than 10 degrees;
• also, together with the entire system, the cable wiring moves from the gear ratio change device to the gearing device (lost motion device) of the handwheel linkage mechanism.

The engagement device connects the right steering wheel to the cable wiring for controlling the spoilers in case of a mismatch of more than 12 degrees (turning the steering wheel).

In the absence of hydraulic power to the aileron steering drives, they will be deflected manually by the pilots, and when the steering wheel is turned at an angle of more than 12 degrees, the cable wiring of the spoiler control system will be set in motion. If at the same time the steering machines of the spoilers will work, then the spoilers will work to help the ailerons.

The same scheme allows the co-pilot to control the spoilers by roll when the commander's control wheel or the aileron cables are jammed. At the same time, he needs to apply a force of the order of 80-120 pounds (36-54 kg) in order to overcome the spring preload force in the aileron transfer mechanism, deflect the steering wheel more than 12 degrees, and then the spoilers will come into operation.

When the right steering wheel or cable wiring of the spoilers is jammed, the commander has the ability to control the ailerons, overcoming the spring force in the steering wheel linkage mechanism.

The aileron rudder is cable-wired to the left steering column via a loading mechanism (aileron feel and centering unit). This device simulates the aerodynamic load on the ailerons, when the steering gear is working, and also shifts the position of zero forces (trim effect mechanism). The aileron trim mechanism can only be used when the autopilot is disabled, as the autopilot controls the rudder directly and will override any movement of the loading mechanism. But at the moment the autopilot is turned off, these efforts will immediately be transferred to the control wiring, which will lead to an unexpected roll of the aircraft. To reduce the chance of unintentional trimming of the ailerons, two switches are installed. In this case, trimming will occur only when both switches are pressed simultaneously.

To reduce effort during manual control (manual reversion) ailerons have kinematic servo compensators (tabs) and balancing panels (balance panel).

The servo compensators are kinematically connected to the ailerons and deviate in the direction opposite to the aileron deflection. This reduces the pivot moment of the aileron and the force on the yoke.

Balancing panel

Balancing panels are panels connecting the leading edge of the aileron to the rear spar of the wing using hinged joints. When the aileron deviates, for example, downwards, a zone of increased pressure appears on the lower surface of the wing in the aileron zone, and a rarefaction zone appears on the upper surface. This differential pressure extends into the area between the leading edge of the aileron and the wing and, acting on the balance panel, reduces the hinge moment of the aileron.

In the absence of hydraulic power, the steering drive works like a rigid rod. The mechanism of the trim effect does not provide a real reduction in effort. You can trim the forces on the steering column using the rudder or, in extreme cases, by varying the thrust of the engines.

pitch control

Control surfaces longitudinal control are: an elevator provided with a hydraulic steering drive, and a stabilizer provided with an electric drive. The pilots' controls are connected to the hydraulic actuators of the elevator using cable wiring. In addition, the input of the hydraulic drives is affected by the autopilot and the M-number trim system.

The normal control of the stabilizer is carried out from the switches on the steering wheels or the autopilot. The backup control of the stabilizer is mechanical using the control wheel on the central control panel.

The two halves of the elevator are mechanically connected to each other by means of a pipe. The elevator hydraulic actuators are powered by hydraulic systems A and B. The hydraulic fluid supply to the actuators is controlled by switches in the cockpit (Flight Control Switches).

One working hydraulic system is sufficient for the normal operation of the elevator. In case of failure of both hydraulic systems (manual reversion), the elevator is deflected manually from any of the steering wheels. To reduce the hinge moment, the elevator is equipped with two aerodynamic servo compensators and six balancing panels.

The presence of balancing panels leads to the need to set the stabilizer to full dive (0 units) before dousing against icing. This setting prevents slush and anti-icing fluid from entering the vents on the trim panels (see aileron trim panels).

The hinge moment of the elevator, when the hydraulic actuator is operating, is not transmitted to the steering wheel, and the forces on the steering wheel are created using the spring of the trim effect mechanism (feel and centering unit), which, in turn, is transmitted forces from the hydraulic aerodynamic load simulator (elevator feel computer) .

Trim effect mechanism

When the steering wheel is deflected, the centering cam rotates and the spring-loaded roller leaves its “hole” on the side surface of the cam. In an effort to return back under the action of the spring, it creates a force in the control leash that prevents the steering wheel from deflecting. In addition to the spring, the actuator of the aerodynamic load simulator (elevator feel computer) acts on the roller. The higher the speed, the stronger the roller will be pressed against the cam, which will simulate an increase in the dynamic pressure.

A feature of the twin piston cylinder is that it acts on the feel and centering unit with the maximum of the two command pressures. This is easy to understand from the drawing, since there is no pressure between the pistons, and the cylinder will be in the drawn state only at the same command pressures. If one of the pressures becomes greater, then the cylinder will shift towards higher pressure until one of the pistons hits a mechanical barrier, thus excluding the cylinder with a lower pressure from work.

Aerodynamic load simulator

The input of the elevator feel computer receives the flight speed (from the air pressure receivers installed on the keel) and the position of the stabilizer.

Under the action of the difference between the total and static pressures, the membrane bends down, displacing the command pressure spool. The greater the speed, the greater the command pressure.

The change in the position of the stabilizer is transmitted to the stabilizer cam, which through the spring acts on the command pressure spool. The more the stabilizer is deflected to pitch up, the lower the command pressure.

The safety valve is activated when the command pressure is too high.

In this way, the hydraulic pressure from hydraulic systems A and B (210 atm.) is converted into the corresponding command pressure (from 14 to 150 atm.) acting on the feel and centering unit.

If the difference in command pressures becomes more than acceptable, the pilots are given a FEEL DIFF PRESS signal, with the flaps retracted. This situation is possible if one of the hydraulic systems or one of the branches of the air pressure receivers fails. No action is required from the crew as the system continues to function normally.

Speed ​​Stability Improvement System (Mach Trim System)

This system is a built-in function of the Digital Aircraft Control System (DFCS). The MACH TRIM system provides stability in speed at M more than 0.615. With an increase in the M number, the MACH TRIM ACTUATOR electromechanism shifts the neutral of the trim effect mechanism (feel and centering unit) and the elevator automatically deviates to pitch up, compensating for the dive moment from the shift of the aerodynamic focus forward. In this case, no movements are transmitted to the steering wheel. Connection and disconnection of the system occurs automatically as a function of the number M.

The system receives the M number from the Air Data Computer. The system is two-channel. If one channel fails, MACH TRIM FAIL is displayed when Master Caution is pressed and goes out after Reset. In case of a double failure, the system does not work and the signal is not extinguished, it is necessary to maintain the M number no more than 0.74.

The stabilizer is controlled by trim motors: manual and autopilot, as well as mechanically, using the control wheel. In case of jamming of the electric motor, a clutch is provided that disconnects the transmission from the electric motors when forces are applied to the control wheel.

Stabilizer control

The manual trim motor control is carried out from the push switches on the pilots' controls, while with the flaps extended, the stabilizer is shifted from more speed than when removed. Pressing these switches disables the autopilot.

Speed ​​Trim System

This system is a built-in function of the Digital Aircraft Control System (DFCS). The system controls the stabilizer using the autopilot servo to ensure speed stability. Its operation is possible shortly after takeoff or during a go-around. Triggering conditions are light weight, rear centering and high engine duty.

The speed stability improvement system works at speeds of 90 - 250 knots. If the computer detects a change in speed, the system automatically turns on when the autopilot is turned off, the flaps are extended (at 400/500 regardless of the flaps), and the N1 engine speed is more than 60%. In this case, more than 5 seconds must elapse after the previous manual trim and at least 10 seconds after liftoff from the runway.

The principle of operation is to shift the stabilizer depending on the change in the speed of the aircraft, so that during acceleration the aircraft tends to nose up and vice versa. (When accelerating from 90 to 250 knots, the stabilizer is automatically shifted 8 degrees to pitch up). In addition to changes in speed, the computer takes into account engine speed, vertical speed and approach to stall.

The higher the engine mode, the faster the system will start to work. The greater the vertical rate of climb, the more the stabilizer works out for a dive. When approaching stall corners, the system automatically turns off.

The system is two-channel. If one channel fails, the flight is allowed. With a double refusal, you can not fly. If a double failure occurs in flight, the QRH does not require any action, but it would be logical to increase speed control during the approach and missed approach phases.

Track control

The directional control of the aircraft is provided by the rudder. There is no servo compensator on the steering wheel. Rudder deflection is provided by one main steering gear and a backup steering gear. The main steering drive is powered by hydraulic systems A and B, and the backup drive is from the third (standby) hydraulic system. The operation of any of the three hydraulic systems fully provides directional control.

Trimming the rudder using the knob on the central console is carried out by shifting the neutral of the trim effect mechanism.

On aircraft of the 300-500 series, a modification of the rudder control scheme (RSEP modification) was made. RSEP - Rudder System Enhancement Program.

The external sign of this modification is an additional display "STBY RUD ON" in the upper left corner of the FLIGHT CONTROL panel.

Path control is carried out by pedals. Their movement is transmitted by cable wiring to the pipe, which, rotating, moves the control rods of the main and backup steering gears. A trim effect mechanism is attached to the same tube.

Wing mechanization

Wing flaps and control surfaces

Transient motor

The figure shows the nature of the transient processes of the engine with the RMS switched off and running.

Thus, when the RMS is running, the position of the throttle determines the given N1. Therefore, during takeoff and climb, the engine thrust will remain constant, with the throttle position unchanged.

Features of motor control when RMS is off

With the PMC turned off, the MEC maintains the set N2 RPM, and as the takeoff speed increases, the N1 RPM will increase. Depending on the conditions, the increase in N1 can be up to 7%. Pilots are not required to reduce power during takeoff as long as engine limits are not exceeded.

When engine mode is selected on takeoff, with PMC disabled, the technology of simulating the outside air temperature (assumed temperature) cannot be used.

In the climb after takeoff, it is necessary to monitor the N1 revolutions and correct their growth in a timely manner by tidying the throttle.

automatic traction

The autothrottle is a computer-controlled electromechanical system that controls the thrust of engines. The machine moves the throttles in such a way as to maintain the specified RPM N1 or the specified flight speed during the entire flight from takeoff to touching the runway. It is designed to work in conjunction with an autopilot and a navigation computer (FMS, Flight Management System).

The autothrottle has the following modes of operation: takeoff (TAKEOFF); climb (CLIMB); occupation of a given altitude (ALT ACQ); cruise flight (CRUISE); decrease (DESCENT); landing approach (APPROACH); missed approach (GO-AROUND).

The FMC communicates to the autothrottle the required operating mode, N1 RPM set, maximum continuous engine RPM, maximum climb, cruise and missed approach RPMs, and other information.

Features of the autothrottle operation in case of FMC failure

In the event of an FMC failure, the autothrottle computer calculates its own N1 RPM limit and displays the "A/T LIM" signal to the pilots. If the autothrottle is in takeoff mode at this moment, it will automatically disengage with an “A/T” failure indication.

The N1 RPM calculated by the machine can be within (+0% -1%) of the FMC calculated Climb RPM (FMC climb N1 limits).

In the go-around mode, the N1 revolutions calculated by the machine provide a smoother transition from approach to climb and are calculated from the conditions for ensuring a positive climb gradient.

Features of the autothrottle operation when the RMS is not working

When the RMS is not working, the position of the throttle no longer corresponds to the specified speed N1 and, in order to prevent overspeed, the autothrottle reduces the front throttle deflection limit from 60 to 55 degrees.

Airspeed

Speed ​​nomenclature used in Boeing manuals:

• Indicated airspeed (Indicated or IAS) - the indication of the airspeed indicator without corrections.
• Indicative ground speed (Calibrated or CAS). The indicated ground speed is equal to the indicated speed, in which aerodynamic and instrumental corrections are made.
• Indicated speed (Equivalent or EAS). The indicated speed is equal to the indicated ground speed corrected for air compressibility.
• True Speed ​​(True or TAS). The true speed is equal to the indicated speed corrected for air density.

Let's start with explanations of speeds in the reverse order. The true speed of an aircraft is its speed relative to the air. The measurement of airspeed on an aircraft is carried out using air pressure receivers (APS). They measure the total pressure of the stagnant flow p* (pitot) and static pressure p(static). Let us assume that the air pressure regulator on the aircraft is ideal and does not introduce any errors and that the air is incompressible. Then the device that measures the difference between the received pressures will measure the velocity air pressure p * − p = ρ * V 2 / 2 . The velocity head depends on both the true speed V, and on the air density ρ. Since the scale of the instrument is calibrated under terrestrial conditions at standard density, then under these conditions the instrument will show the true speed. In all other cases, the device will show an abstract value called indicator speed.

Indicated speed V i plays an important role not only as a quantity necessary to determine the airspeed. In horizontal steady flight for a given aircraft mass, it uniquely determines its angle of attack and lift coefficient.

Considering that at flight speeds of more than 100 km/h, air compressibility begins to appear, the real pressure difference measured by the device will be somewhat larger. This value will be called the terrestrial indicator speed V i 3 (calibrated). Difference V i − V i 3 called the compressibility correction and increases with altitude and airspeed.

A flying plane distorts the static pressure around it. Depending on the installation point of the pressure receiver, the device will measure slightly different static pressures. The total pressure is practically not distorted. Correction for the location of the static pressure measurement point is called aerodynamic (correction for static source position). An instrumental correction for the difference between this device and the standard is also possible (for Boeing it is taken equal to zero). Thus, the value shown by a real device connected to a real HPH is called the indicated speed.

On the combined indicators of speed and number M, the ground indicator (calibrated) speed is displayed from the computer of altitude and speed parameters (Air data computer). The combined speed and altitude indicator displays the indicated speed, obtained from pressures taken directly from the HPH.

Consider typical malfunctions associated with PVD. Typically, the crew recognizes problems during takeoff or shortly after liftoff. In most cases, these are problems associated with freezing of water in pipelines.

In the event of a blockage in the pitot probes, the airspeed indicator will not show an increase in speed during the takeoff roll. However, after liftoff, the speed will begin to increase as the static pressure decreases. The altimeters will work almost correctly. On further acceleration, the speed will increase through the correct value and then exceed the limit with the corresponding alarm (overspeed warning). The complexity of this failure is that for some time the instruments will show almost normal readings, which can give the illusion of restoring the normal operation of the system.

If the static ports are blocked during the takeoff run, the system will operate normally, but during the climb it will show a sharp decrease in speed down to zero. The altimeter readings will remain at the airfield altitude. If pilots try to maintain the required speed readings by reducing the climb pitch, then, as a rule, this ends up exceeding the maximum speed limits.

In addition to cases of complete blockage, partial blockage or depressurization of pipelines is possible. In this case, it can be much more difficult to recognize a failure. The key point is to recognize systems and instruments that are not affected by the failure and complete the flight with their help. If there is an indication of the angle of attack - fly inside the green sector, if not - set the pitch and rpm of the N1 engines in accordance with the flight mode according to the Unrelaible airspeed tables in QRH. Get out of the clouds as much as possible. Ask for assistance from the traffic service, given that they may have incorrect information about your flight altitude. Do not trust instruments whose readings were suspect, but in this moment seem to work correctly.

As a rule, reliable information in this case: inertial system (position in space and ground speed), engine speed, radio altimeter, stick shaker operation (approaching stall), EGPWS operation (dangerous ground proximity).

The graph shows the required engine thrust (aeroplane drag force) in level flight at sea level in a standard atmosphere. Thrust is in thousands of pounds and speed is in knots.

Takeoff

The take-off path extends from the starting point to a climb of 1500 feet, or the end of flap retraction at airspeed. V FTO (final takeoff speed), which of these points is higher.

The maximum takeoff weight of an aircraft is limited by the following conditions:

1. The maximum allowable energy absorbed by the brakes in the event of a rejected takeoff.
2. The minimum allowable climb gradient.
3. The maximum allowable engine operation time in take-off mode (5 minutes), in the event of a continued take-off to gain the required altitude and accelerate to retract mechanization.
4. Available takeoff distance.
5. The maximum allowable certified takeoff weight.
6. The minimum allowable clearance over obstacles.
7. The maximum allowable ground speed of separation from the runway (according to the strength of the tires). Typically 225 knots, but possibly 195 knots. This speed is written directly on the pneumatics.
8. Minimum evolutionary takeoff speed; V MCG (minimum control speed on the ground)

Minimum Permissible Climb Gradient

In accordance with the airworthiness standards FAR 25 (Federal Aviation Regulations), the gradient is normalized in three segments:

1. With undercarriage extended, flaps in takeoff position - the gradient must be greater than zero.
2. After gear retraction, flaps in takeoff position - minimum gradient 2.4%. Take-off weight is limited, as a rule, to the fulfillment of this requirement.
3. In cruising configuration, the minimum gradient is 1.2%.

takeoff distance

The takeoff field length is the operational length of the runway, taking into account the end safety strip (Stopway) and clearway.

The available take-off distance cannot be less than any of the three distances:

1. Take-off distances from start of motion to 35 ft screen height and safe speed V 2 at engine failure at decision speed V 1 .
2. Aborted takeoff distances, with engine failure at V EF. Where V EF(engine failure) - speed at the moment of engine failure, it is assumed that the pilot recognizes the failure and performs the first action to abort the takeoff at the decision speed V 1 . On a dry runway, the effect of running engine reverse is not taken into account.
3. Take-off distances with normally operating engines from the start of the movement to the climb of a conditional obstacle of 35 feet, multiplied by a factor of 1.15.

Take-off distance available includes runway operating length and stopway length.

The length of the clearway may be added to the available takeoff distance, but not more than half of the airborne takeoff path from the takeoff point to a climb of 35 feet and a safe speed.

If we add the length of the runway to the runway length, then we can increase the takeoff weight, and the decision speed will increase, to provide a climb of 35 feet over the end of the runway.

If we use a clearway, we can also increase the takeoff weight, but this will reduce the decision speed, since we need to ensure that the aircraft is stopped in the event of a rejected takeoff with an increased weight within the operating length of the runway. In the event of a continued takeoff, the aircraft will then climb 35 feet off the runway but over the clearway.

Minimum Permissible Obstacle Clearance

The minimum obstacle clearance allowed on the net take-off path is 35 feet.

A "clean" takeoff path is one whose climb gradient is reduced by 0.8% compared to the actual climb gradient for the given conditions.

When constructing a scheme for a standard exit from the aerodrome area after takeoff (SID), a minimum gradient of a “clean” trajectory of 2.5% is laid down. Thus, in order to fulfill the exit scheme, the maximum takeoff weight of the aircraft must provide a climb gradient of 2.5 + 0.8 = 3.3%. Some exit patterns may require a higher gradient, requiring a reduction in takeoff weight.

Minimum evolutionary takeoff speed

This is the ground reference speed during the takeoff run at which, in the event of a sudden failure of a critical engine, it is possible to maintain control of the aircraft using only the rudder (without the use of nose gear wheel control) and maintain lateral control to such an extent as to keep the wing close to horizontal. to ensure a safe continuation of the takeoff. V MCG does not depend on the state of the runway, since its determination does not take into account the reaction of the runway to the aircraft.

The table shows V MCG in knots for takeoff with engines with 22K thrust. Where Actual OAT is the outside air temperature and Press ALT is the airfield elevation in feet. The underscript refers to takeoff with the engine bleeds off (no engine bleeds takeoff), as engine thrust increases, so does V MCG .

For A/C OFF increase V1(MCG) by 2 knots.

A takeoff with a failed engine may only be continued if the engine failure occurs at a speed of at least V MCG .

Wet runway takeoff

When calculating the maximum allowable takeoff weight, in the event of an extended takeoff, a reduced screen height of 15 feet is used instead of 35 feet for a dry runway. In this regard, it is impossible to include a clearway in the calculation of the takeoff distance.

IN technical specifications aircraft everything matters. Indeed, the viability of the liners and the safety of the people on board depend on literally every little thing. However, there are parameters that can be called basic. An example of this is the takeoff and landing speed of an aircraft.

For the operation of aircraft and their operation, it is extremely important to know what exactly the speed of the aircraft can be during takeoff, namely at the moment when it takes off from the ground. For different models of liners, this parameter will be different: for heavier cars, the indicators are larger, for lighter cars, the indicators are smaller.

Takeoff speed is important because designers and engineers involved in the manufacture and calculation of all aircraft characteristics need this data to understand how much lift will be.

Different models have different takeoff and takeoff speed parameters. For example, the Airbus A380, which today is considered one of the most modern aircraft, accelerates on the runway to 268 km per hour. The Boeing 747 will need a run of 270 km per hour. The Russian representative of the aviation industry Il 96 has a takeoff speed of 250 km per hour. For Tu 154, it is equal to 210 km per hour.

But these figures are presented as an average. After all, a number of factors affect the final acceleration speed of the liner along the strip, including:

• Wind speed
• Direction of the wind
• Runway length
• Atmosphere pressure
• Humidity of air masses
• Runway condition

All this has its effect and can both slow down the liner and give it a slight acceleration.

How exactly does takeoff happen?

As experts note, the aerodynamics of any air liner is characterized by the configuration of the aircraft's wings. As a rule, it is standard and the same for different types aircraft - the lower part of the wing will always be flat, the upper - convex. The difference is only in small details, and does not depend on the type of aircraft.

The air passing under the wing does not change its properties. But the air that is on top begins to narrow. This means that less air flows from the top. This ratio causes a pressure difference around the wings of the liner. And it is she who forms the same lifting force that pushes the wing up, and with it lifts the plane.

The lift off of the aircraft from the ground occurs at the moment when the lifting force begins to exceed the weight of the liner itself. And this can only happen with an increase in the speed of the aircraft itself - the higher it is, the more the pressure difference around the wings increases.

The pilot also has the opportunity to work with lift - for this, flaps are provided in the wing configuration. So, if he lowers them, then they will change the lift vector to a sharp climb mode.

The smooth flight of the liner is ensured when a balance is maintained between the weight of the liner and the lifting force.

What are the types of takeoff

To accelerate a passenger aircraft, pilots need to select a special engine operation mode called takeoff. It only lasts a few minutes. But there are exceptions, when some settlement is located near the airfield, the aircraft in this case can take off in the usual mode, which reduces the noise load, because. during takeoff, the aircraft engines roar very loudly.

Experts distinguish two types of take-off of passenger liners:

1. takeoff with brakes: it means that at first the aircraft is held on the brakes, the engines switch to maximum thrust, after which the liner is removed from the brakes and the takeoff begins
2. Takeoff with a short stop on the runway: in this situation, the liner begins to run along the runway immediately without any preliminary rearrangement of the engines to the required mode. After the speed increases and reaches the required hundreds of kilometers per hour

Landing nuances

By landing, pilots understand the final stage of the flight, which is the descent from the sky to the ground, the slowdown of the liner and its complete stop on the runway near the airport. The descent of the aircraft starts from 25 meters. And in fact landing in the air takes only a few seconds.

When landing, pilots face a whole range of tasks, because. It happens in fact in 4 different stages:

1. Leveling - in this case, the vertical rate of descent of the liner goes to zero. This stage starts 8-10 meters above the ground and ends at 1 meter
2. Soak: in this case, the liner's speed continues to decrease, and the descent remains smooth and continuous
3. Parachuting: during this stage, there is a decrease in the lift of the wings and an increase in the vertical speed of the aircraft
4. Landing: it is understood as direct contact with a hard surface of the chassis

It is at the landing stage that the pilots fix landing speed aircraft. Again, depending on the model, the speed also varies. For example, for a Boeing 737, it will be 250-270 km per hour. Airbus A380 sits down with the same parameters. If the plane is smaller and lighter, 200 km per hour will be enough for it.

It is important to understand that landing speed is directly affected by exactly the same factors that affect takeoff.

The time intervals here are very small, and the speeds are huge, which causes the most frequent disasters at these stages. After all, pilots have very little time to make strategically important decisions, and every mistake can be fatal. Therefore, a lot of time is devoted to practicing landing and takeoff in the process of pilot training.