Summer school. Airspeeds - tutorial

true airspeed (TAS)

The actual speed at which the aircraft is moving relative to the surrounding air due to the thrust of the engine(s). The velocity vector generally does not coincide with the longitudinal axis of the aircraft. Its deflection is affected by the angle of attack and aircraft glide;

instrument speed (IAS)

The speed indicated by an airspeed instrument. At any height, this value unambiguously characterizes the carrying properties of the airframe at a given moment. Meaning indicated speed used in aircraft piloting;

Ground speed ()

V1 depends on many factors, such as: weather conditions (wind, temperature), runway pavement, aircraft takeoff weight and others. In the event that the failure occurred at a speed greater than V1, the only solution would be to continue the takeoff and then land. Most types of GA aircraft are designed in such a way that even if one of the engines fails on takeoff, the remaining engines will be enough to, after accelerating the car to a safe speed, rise to the minimum height from which you can enter the glide path and land the aircraft.

Va

Estimated maneuvering speed. The maximum speed at which full deflection of the control surfaces can be performed without overloading the aircraft structure.

VR

The rate at which the front landing gear lift begins.

V2

Safe takeoff speed.

Vref

Estimated landing speed.

Vtt

The specified runway edge crossing speed.

Vfe

Maximum allowed speed with flaps extended.

Vle

Maximum allowed speed with landing gear extended.

vlo

Maximum landing gear extension/retraction speed.

vmo

V maximum operating - maximum operating speed.

Vne

Unbeatable speed. The speed marked with a red line on the airspeed indicator.

Vy

Optimal climb rate. The speed at which an aircraft reaches maximum altitude in the shortest time.

Vx

The speed of the optimal angle of climb. The speed at which the aircraft will gain maximum altitude with minimum horizontal movement.

Vertical speed

Change in flight altitude per unit of time. Equal to the vertical component of the speed

The Boeing 737 is not a Cessna Skyhawk, flying it involves many different procedures and complex systems.

To fly a Boeing 737, it is necessary to learn various key concepts, diagrams and procedures. Careful planning is the key to successful jet piloting. In this lesson, you will take off, make a simple flight with several turns, descend and land the plane. After the first landing of this kind, you will not be the same. No, I don't mean that you will be completely mangled and need a chiropractor. What I meant to say is that after that you will have such a big smile on your face that the neighbors will think that you are showing off your new teeth to them.

Jet Pilot Basics

To better understand the principles of piloting a Boeing 737-800 in the Flight Simulator game, let's study this aircraft and its flight modes in more detail. The information we need covers various airspeed parameters, flight modes and instruments. Below are ordered descriptions of the general stages of flight. For a simplified flight description, see the Quick Start section.

flight profiles

A flight profile is an aircraft configuration that includes speed, engine power, pitch angle, flap angle, and landing gear position. The side view of the plane has nothing to do with it. At each individual stage of flight (takeoff, cruise, descent, approach and landing), the aircraft is assigned a specific profile. Fine-tuning the profile parameters is the key to a successful flight. Let's take a closer look at each flight stage and the configuration used in it.

What is a flight profile?

A flight profile is a predetermined aircraft configuration used during a particular phase of flight. The words "preset" mean that the airline or aircraft manufacturer has set the profile parameters to ensure a safe and controlled flight. Typical flight phases are takeoff, departure, cruise climb, approach initiation and various instrument approach systems for which the aircraft is certified (UIS, VOR, GPRS, GPS, CAT III, etc.).

Profiles help the pilot to set up the aircraft configuration, control it at each point in the flight and move from one phase of flight to another. The actual speeds and masses that the pilot is expected to look for in the charts are usually not shown in the profile - they list "standard" speeds. To make it easier for you to fly a training flight (and keep your brain from boiling over), the following is the minimum necessary information. To go to a quick guide to any of the profiles described in this section, select the appropriate link:

Take the time to study each profile (you can even print them out), and then feel free to try out the knowledge in practice. If you feel that you need to think about your plan of action better, feel free to pause the game, otherwise your heart may stop from an overabundance of information. Remember, these profiles are needed to make it easier for you to understand the principles of controlling the Boeing 737-800 in Flight Simulator. They do not cover every single issue, parameter, or standard action plan for any airline or aircraft manufacturer. Have fun and think about what will happen the next time you take the controls of a commercial airliner.

Takeoff

• Takeoff Weight Calculation
• Setting the flaps to the takeoff position
• Determination of takeoff speed
• Determination of the time or speed at which flaps should be retracted

cruising flight

• Choice of altitude and cruise speed
  (or flying in a circle over the airfield)

Decrease (refer to activity 2 for details)

• Selecting the start of the descent
• Landing weight determination
• Choice of flap configuration during descent
• Determining Approach Speed ​​Based on Weight and Conditions

Approach

• Speed ​​control
• Aircraft configuration management

Landing

• Changing the configuration
• ILS approach or visual approach
• Sliding along the center line
• Aircraft stop

About takeoff weight

One of the most important characteristics of the Boeing 737-800 is its weight. The mass of an aircraft is taken into account at various stages of flight to determine parameters such as takeoff speed, landing speed, and flap extension and retraction speed. In flight, the aircraft burns fuel. The more fuel an aircraft uses, the lighter it becomes. The key point here is that the mass of the aircraft decreases from the beginning to the end of the flight.

First of all, you need to know takeoff weight And aircraft landing weight. Both of these parameters, in combination with the outside air temperature and density altitude, are used to determine takeoff and landing speeds. Too difficult? Maybe so, but we will simplify everything by using certain assumptions and settings for the Boeing 737-800, set by default in Flight Simulator.

Operating restrictions used in Flight Simulator by default

You may have noticed that the maximum taxi weight exceeds the maximum takeoff. This discrepancy is taken into account the fuel that you will burn while taxiing on the airfield and waiting for your turn to take off.

It is also worth paying attention to the fact that the maximum landing weight is less than the maximum takeoff. This means that you can't just pick up and land the plane immediately after takeoff - it's too heavy, so you need to fly in a circle before landing.

Weight without fuel is the total weight of the aircraft fully loaded with baggage and passengers, but absolutely without fuel. Knowing this mass allows you to determine the actual weight of the aircraft at any given time. To do this, add the mass of the current fuel supply to the mass without fuel.

In Flight Simulator, you can easily change the fuel load level. The Boeing-737-800 aircraft has three fuel tanks: left, right and center.

The numbers show us that the total mass of fuel is 46,063 pounds (20,894 kg). To calculate the mass of the aircraft without fuel (which we will use later as a base value), subtract the mass of fuel from the maximum takeoff mass (174,200 lbs or 79,016 kg) and get 128,137 lbs (58,122 kg).

Flaps on takeoff: retract or release?

On takeoff, commercial airline pilots use different flap profiles depending on aircraft weight, runway length, temperature, density altitude, and surface conditions. For each set of takeoff conditions, the optimal flap angle is calculated (it is possible that airlines hire additional pilots for these calculations). But we will not go into the math, but we will extend the flaps to an angle of 5 degrees on takeoff and take off using the default settings of the game.

Takeoff speed control

Determination of takeoff speed

Speed ​​control is very important when flying a Boeing 737. To determine the exact takeoff and landing speeds, you need to look at various tables (like in a mirror, to the point of insanity), take into account the configuration of the aircraft, mass, temperature and density altitude. In this training flight, we will take the easy way and set the external conditions equal to the so-called. "standard day".

Speeds in special cases

The three speeds most important for takeoff are V1, Vr and V2. This is the so-called. "velocities in special cases". The correct choice of this speed depends on the mass of the aircraft, external conditions and the takeoff profile of the flaps. By setting the weight of the aircraft to the model's standard weight in Flight Simulator, standard conditions, and a 5-degree flap angle, we can simplify the selection of speeds to a single set of values.

V1 is takeoff decision speed. The length of a runway that provides a safe takeoff depends on the aircraft takeoff weight, temperature and density altitude. While moving in takeoff mode, the aircraft reaches a certain point at which it is necessary to make a decision to take off or stop. When piloting a Boeing 737, this point is determined by the speed of the aircraft and is designated V1. Before the plane has reached V1, you could theoretically rev the engine, brake, and stop within the runway without letting the plane become an oversized all-terrain vehicle. Exceeding the speed, V1 you are doomed to rise. Based on the assumptions made above, we will take the speed V1 in this training flight equal to 150 knots.

VR is nose landing gear lift speed. At this speed, the pilot takes over the yoke, raises his nose to the desired pitch angle (+20 degrees) and takes off. Let's take Vr as an indicated airspeed of 154 knots. It should be borne in mind that by raising the nose of the Boeing too high during takeoff, you can accidentally touch the tail with the strip, thereby slightly shortening it. To keep the tail from hitting the ground, increase the pitch gradually, bringing it up to 20 degrees no faster than 3 degrees per second.

V2 is minimum safe takeoff speed. Even if the engine fails immediately after V1 picks up speed, the generated thrust will be enough to take off at a given vertical speed and height above the terrain. Since take-offs can be made with different flap configurations, the climb speed for a twin-engine aircraft, which is considered the minimum allowable while maintaining control, is set to V2+15 knots. This speed is suitable for any takeoff flap configuration.

If during takeoff you listened to the instructor, you heard him report the situation:

Power setting

Now we know how takeoff speed depends on the mass of the aircraft and external conditions. But how to set the power of the engines in such a way that the plane moves at a given speed?

Rice. 1-2. Motor indicators

The power of a turbojet aircraft engine is not measured in absolute revolutions per minute, as in piston aircraft, but as a percentage of the maximum number of revolutions, that is, of the rated engine power. The two main power ratings for a Boeing 737-800 engine are the low pressure turbine shaft speed (N1) and the high pressure turbine shaft speed (N2).

The value of N1 is measured in %% of the maximum speed of the low pressure turbine shaft. This value best describes the engine power. It changes by moving the throttle, which allows you to set a given airspeed.

The value of N2 is measured as %% of the maximum speed of the high pressure turbine shaft and indicates the speed of rotation of the compressor blades. This speed must not exceed the maximum allowable design speed. The display of the N2 value on the indicator allows you to monitor compliance with the limit.

In this training flight, we will focus on controlling the N1 value.

We take off

Now that we know enough about mass, flap deflection, and target airspeeds, we can move onto the runway and take off. You can start the training flight right from the center line of the runway of the departure airfield or from the loading point, but before that, you should set up the radio navigation instruments and the autopilot, run your eyes over the checklist, set the flaps to 5 degrees, and only then ask ATC for taxi clearance and takeoff.

Regardless of how you ended up on the runway, it is worth checking and adjusting all the equipment, as well as making a plan for taking off. Typically, crews follow a standard departure procedure to obtain an instrument clearance. The game also simplifies the process of giving speed and runway runway. Departure always follows a certain pattern, among the points of which there is an airspeed limit of 200 knots below 3,000 feet and 250 knots between 3,000 and 10,000 feet.

Takeoff

Airspeed limit

The rules of the air prescribe certain speed limits. Their observance, by the way, will be checked during your control flight. When departing from an aerodrome surrounded by Class B airspace, the speed below 10,000 feet must not exceed 250 knots. In Class C and D spaces, the limit is reduced to 200 knots (aerodrome airspace is generally defined as an area within a 4-mile radius and up to 2,500 feet), and from the moment you leave the airfield until you reach 10,000 feet, it is 250 knots. These limitations are the key to understanding the pilot's actions during takeoff. For details contact Dictionary and articles on air traffic control.

takeoff clearance

Having set up all the instruments and received permission to take off, bring the engine speed to 40-50% of the nominal, keeping the aircraft on the brakes. This procedure serves two purposes. Firstly, you can review the instruments to make sure that they work and their readings are normal (yes, pilots have other norms besides the nutritional norm). Secondly, the resulting pause gives the engines the opportunity to pick up speed to an average level, and at the same time you do not risk overheating the brakes by examining the instruments. After making sure that the power of both engines is the same and the instrument readings are normal, release the brakes and set the speed to 95 percent of N1. Please note that the throttle on this aircraft is much more sensitive than on the Cessna Skyhawk SP or Beechcraft Baron 58. Instead of immediately moving the throttles to full power, set them to three-quarters of the power and slowly increase the power until it reaches 95% of N1. Or move the throttle forward until it stops, and then slow down the thrust so that it does not exceed 95%.

Now, as the aircraft accelerates along the center line of the runway, you need to monitor its speed. The first milestone speed is the speed of making a decision when there is no going back. Make sure all devices are in good working order. If so, continue your takeoff. The next important speed is the front strut lift speed. At 154 knots, take the helm and take off. Bring the pitch up to +20 degrees with a nose up speed of about 3 degrees per second. It is easy to calculate that it will take approximately 6.5 seconds to reach this pitch angle.

Parameters are normal - remove chassis

After gaining a pitch of 20 degrees and leveling the plane in roll, check the variometer and altimeter. If their parameters are normal, then the rate of climb is maintained and you can retract the landing gear. This should not be done without a proper climb rate as the aircraft is too close to the ground and could touch the runway again due to wind shear, nose-pillar up at too low a speed, excessively high pitch angle, alien force field (just kidding, just kidding) and others. reasons. The landing gear is retracted with the key G or the corresponding button on the joystick.

Flap retraction

At the initial stage of departure, pilots establish the appropriate profile of the aircraft in order to protect it from collisions with the ground and obstacles, as well as to ensure sufficient rate of climb in the event of an engine failure. To perform this procedure, you must be 400 feet above the ground with flaps extended 5 degrees while maintaining a speed of 180 knots. This will help you set the pitch angle to 20 degrees. The second main element of departure is climbing to a safe altitude of 1000 feet above ground level with sufficient climb and airspeed. Having reached the set values, you can proceed to the next stage of takeoff.

After reaching 1000 feet above ground level, retract the flaps according to the takeoff profile. At this point you should be flying at V2+15 (162+15) while gaining altitude. Now you can start cleaning the flaps. Decrease the flap angle from 5 to 1 degree by pressing the F6 key twice. Set the engine power to 90% of nominal, reduce the pitch angle to 15 degrees and pick up speed. After climbing above 2500 feet above ground level, reduce the pitch to 10-12 degrees and gain speed to 250 knots. When the speed exceeds 200 knots, complete the retraction of the flaps. It also helps to complete the "After takeoff" checklist.

cruising flight

Cruise climb

Maintain a pitch of 10-12 degrees and a speed of 250 knots at 90% of N1 until you are above 10,000 feet. Then reduce the pitch to 6 degrees and increase the speed to 280-300 knots. The higher you climb, the thinner the air becomes, which affects the performance of the engines. Adjust the thrust to keep it at 90%. As you climb, you may need to lower your pitch to 5-6 degrees to maintain a speed of 280 knots.

Before reaching 1,000 feet of cruising altitude, lower your nose and maintain a vertical speed of 1,500 feet per minute. When you are 150 feet from cruising altitude, begin leveling off by reducing the pitch to 2 degrees while dropping RPM to 70-72%. Don't forget to level the plane in pitch with the trim tabs. You can now turn on the autopilot to maintain heading, altitude, and airspeed (although I personally prefer to fly the Boeing 737 myself on short flights). On long flights, the autopilot will help you even more than the co-pilot - except for coffee.

decline

We've covered the basic steps of takeoff, climb, and flare. Now we should take care of the decline and how we get to the right place with the right speed and height. Descending is all about session 2, but here we'll take a quick look at your actions on this training flight.

When it's time to descend, there are a few important things you need to do to be in the right place at the right time. Here is what the aircraft crew must do before the start of the descent.

• Schedule the start of the descent.
• Obtain an Automatic Information Service (ATIS) summary and other approach and landing information.
• Calculate the approximate landing weight of the aircraft.
• Determine flap position and approach speed.
• Determine arrival runway and approach route.
• Instruct the crew on the landing approach features.
• Perform control operations of the checklist for the "Reduction" section.

When should you slow down?

Maintaining speed is very important for piloting. It plays a role at two points: during descent, at the entry into the denser atmosphere, and at the leveling point, where speed reduction may be required to comply with the speed limit (for example, a 250 knot limit).

As we descend into the denser layers of the atmosphere, instead of percentages of the speed of sound (Mach number), the unit of measurement of the indicated speed will again become nautical miles per hour (knots). You can determine the transition threshold by the red and white striped bar or arrow. This arrow shows maximum allowed speed aircraft. On descent, the striped needle approaches the airspeed needle and, if left unattended, may cross it. This means that the aircraft has exceeded the permissible speed, which will be announced by the clicks of the horn (and strange sounds made by the co-pilot). To avoid overspeeding, reduce thrust to 45% and maintain 310-320 knots for the rest of the descent.

When descending from cruising altitude, the aircraft retains its driving force - after all, its speed exceeds 300 knots. You do not need such acceleration at all, the speed should decrease. This is not at all difficult to do, passengers do not even have to put their hands out of the windows. When planning a descent, add 5 nautical miles to level off and reach a given speed in idle mode (yes, here, unlike the Baron, you can immediately move the throttle to idle without fear of overcooling the engine). The result is something like this: descend at about 300 knots, level off at about 10,000 feet, idle, and coast for about 5 nautical miles until speed drops to 250 knots. Then we set the thrust to 52-55% and maintain this speed.

As a last resort, spoilers can always be used by releasing and retracting them with the key / . Accurate action planning will prepare you well for approach and landing.

Approach planning

From the information reported by the automatic information service (ATIS), of particular interest are: local weather conditions, airfield pressure (which you will set the altimeter to when descending from FL180), active runway, aircraft reception restrictions, occupied runways and taxiways. This information will help you prepare for your landing approach.

landing weight

The descent calculation is usually made 100-120 miles (approximately 20-25 minutes) before touchdown. To calculate landing weight, click ALT+A+F and find out your current fuel capacity. If you're above 25,000 feet, it's pretty safe to say that you'll burn 1,700 pounds of fuel during your descent, approach, and landing. Subtract 1,700 pounds from your current fuel capacity and then add 100,000 pounds to the result to get an approximate landing weight.

Landing flap position

Landing flap position depends on many factors such as runway length, approach parameters, runway conditions, weather conditions and fuel efficiency. In order not to deviate from the easy path, we will extend the flaps at 30 degrees on all landings in these training flights.

Landing speed

As you approach and land, you will continually decrease your airspeed while maintaining the airspeed limit for your aircraft configuration. A good landing is a soft landing, and if you fly too slowly, the plane will just flop into the runway. You now need to maintain the desired airspeed, taking into account the position of the flaps and the mass of the aircraft. At too low a speed, the aircraft will become difficult to control, or worse, stall and land sooner than desired. Here, as well as on takeoff, there are certain speeds that provide optimal flight performance and protect the aircraft from stalling and other undesirable incidents. The airspeed that defines the line between controllable and not-quite-controllable flight is called "approach speed for weight and conditions" (Vref).

For greater safety and better flying qualities, an additional 5 knots are added to this speed. Therefore, if the speed determined for a given aircraft landing weight and flap deflection is Vref, the actual approach speed will be Vref+5 knots. In strong crosswinds or wind shear, another 10 knots can be added to this value. Do you remember flying on the Skyhawk SP fondly now? I understand you. All this is not easy, but such is jet aviation.

And when are all these calculations carried out? At the descent planning stage, the crew calculates the landing weight and selects the desired flap angle. Knowing the mass of the aircraft and the deflection of the flaps, you can calculate the speed Vref.

landing briefing

Now that you know the weather conditions of the airfield, the pressure on it and the working runway of arrival, you can prepare for the landing approach. It's time to look at the entry scheme.

It is unlikely that you will now tune the radio and the entrance course. These actions are included in the "Approach" section of the screening chart. We still need to follow the standard arrival procedure and follow the instructions of the controllers who direct us to the approach path.

Approach

We've covered the principles of descent planning and speed control, now it's time to learn more about the arrival airfield. HUD approach is covered in session 3, and here you will learn the basics of landing on a runway. If you have turned on ATC in the game, then you will be "guided" (set the flight course) to the approach trajectory. If you are flying "on your own", you will have to time your flight to land on a landing course at a certain altitude and speed.

The general rule here is this: at a distance of 10 nautical miles from the airfield, you should fly at an altitude of 3000 feet above ground level; the aircraft must be properly configured and oriented to a localizer or visual glide path indicator. When approaching the 10-mile mark, reduce speed so that it does not exceed 170 knots, set the flaps to 5 degrees. When the glide path indicator bars go off scale, you need to extend the landing gear, increase the flap angle to 15 degrees and reduce the speed to 150 knots. At this distance and altitude, you will soon acquire (if not already acquired) the glide path. Keep in mind that these values ​​are approximate and are meant to get you closer to a 3 degree glide path. At the checkpoint of the last stage of the approach, set the flaps to the landing configuration (30 degrees), RPM to 53-55% and smoothly descend along the glide path.

You can also study (and even print) the look-up tables for approach and landing: Visual straight-in approach.

So, you're following the localizer beam exactly, glide path indicator needles off scale, landing gear extended, flaps at 15 degrees, speed reduced to 150 knots (or to your Vref, if you prefer a more realistic game). You are ready to grab the glide path and land on it onto the runway. At the moment when the glide path rises one point above the center, set the flaps to 30 degrees and the RPM to 53%. Begin to decrease the pitch to zero and keep an eye on the instruments so that you do not go left or right off the course and down or up from the glide path.

Landing alignment and landing

After passing over the end of the runway, set the idle throttle and gradually increase the pitch to 3 degrees. This is called landing alignment. Hold pitch as you decelerate and you will land on the runway. When leveling off, do not stop correcting your course so as not to drift off the center line; the plane must be under your control at all times. Be sure to align your heading so that the letters "GPS" on the instrument panel are on centerline - this will help you stay on course when touched down. Don't let yourself look at the nose of the plane. Focus on the opposite end of the runway. When the main landing gear touches the strip, slowly lower the nose gear. Engage thrust reverser (press and hold the F2) and brakes (key "Dot" [.]) to slow down and steer out of the lane on the nearest free taxiway. To make it easier to stop the aircraft after touchdown, you can use automatic braking.

OK it's all over Now. Now you are almost a fac. You have learned a lot, but there is still a lot to learn. To better absorb all the information presented here, you may need to repeat this flight several times. It's okay, I'll wait for you. If you feel ready, take to the skies. The main thing is that you like it.

You can also study (and even print out) the look-up tables for approach and landing: Circling Approach and How to HUD Approach.

That's it, see you in the cockpit. To apply the acquired knowledge in practice, select the link Start training flight.

When determining the maximum take-off mass of an aircraft and take-off speeds, a number of new definitions are used:

1) Location height- atmospheric pressure, expressed in units of height in accordance with the international standard atmosphere.

2) climb gradient the tangent of the slope of the climb path, expressed as a percentage. For the Il-86 aircraft, a full climb gradient of at least 35% is considered in the climb section from the moment the landing gear is retracted to the climb-altitude of 120 m with one failed engine and flaps deflected by 30 °, slats - by 25 °.

Gradient η n = tg θ n 100%

The total climb gradient is the maximum achievable climb gradient under the operating conditions under consideration.

The net climb gradient is the most probable value of the climb gradient under the considered operational conditions in the mass operation of the aircraft.

3) Full flight path- flight trajectory built on the full climb gradient. The full takeoff path is the takeoff path plotted from the full takeoff climb gradient.

4) Net flight path- trajectory constructed from a pure takeoff climb gradient.

5) Stall speed V Wed- the minimum speed of the aircraft, obtained in flight tests, when braking the aircraft in straight flight.

6) Safe Takeoff Speed V 2 - a speed that is at least 20% higher than the minimum stall speed. This is the minimum speed at which an aircraft with one engine failed can be brought into a roll climb without slipping.

7) Decision making speed V 1 - the highest speed at which the pilot, having detected a failure of one engine, must decide whether to continue or stop the takeoff (pilot reaction time 3s).

8) Aircraft nose gear break-off speed V R= V p st- 3% less aircraft takeoff speed.

9) Relative decision speed V1/V2 - the ratio of the speed of decision-making to the speed of separation of the front support. Needed to find the speed of decision making.

10) Available takeoff run– runway length reduced by the taxiway length (100m).

11) Slow takeoff distance available- a distance equal to the sum of the length of the runway, reduced by the length of the taxi section, and the length of the end safety strip (LSB), in the direction of which the take-off is made (Fig. 17).

12) Available Takeoff Distance (RDV)- a distance equal to the sum of the length of the runway, reduced by the length of the taxi section, the length of the landing zone, and the free zone of the air approach strip. The section of the free zone included in the WFD should not exceed 0.5 of the runway length.

PVP - a section from the end of the CPB, free from obstacles with a height of more than 10.7 m (35 ft) (Fig. 18).

13) Required rejected takeoff distance- the sum of the takeoff run length with four running engines from the starting point to the failure point of one engine, the acceleration length to V 1 , with three engines running and the length of the deceleration section until the aircraft comes to a complete stop (see Fig. 17).

14) Required extended takeoff length- the sum of the takeoff run with four engines running from the starting point to the point of failure of one engine, the length of the takeoff run on three engines from the point of failure to the takeoff point and the length of the air section of the takeoff distance to a climb of 10.7m (35ft) (see Fig. 17) .

15) Required takeoff run- this is a conditional value equal to the sum of the actual length of the takeoff run of the aircraft up to the take-off speed in the event of failure of one engine at a speed V 1 and 1/2 air leg lengths takeoff distance to climb 10.7 m (35 ft).

Note. The condition for determining the take-off mass is the requirements - the required takeoff run length does not exceed the available length of the runway for the runway, the required length of the continued take-off does not exceed the available length for the continuation of the take-off, the required length of the rejected take-off does not exceed the available length of the rejected take-off.

16) Balanced runway length- or balanced take-off distance D - available runway + CPB, on which in case of failure of one engine at speed V 1 aircraft can complete both an aborted takeoff to a complete stop, and a continued takeoff to a climb of 10.7 m with acceleration up to V without = V 2 (see fig. 17).

17) D consum- the required section of the aborted takeoff, equal to the required section of the continued takeoff. At m\u003d 210t and engine failure at V \u003d 240-260km / h D cont \u003d 3000m. The condition for determining the take-off mass according to D - is the requirement that D expended within D dist.

18) Under non-standard conditions, D - a parameter that depends on the available short takeoff distance (RWY + KPB - 100m), the available distance for continued takeoff (VSHYSHP-SHOM) slope, wind, runway condition. If the conditions are favorable, then D increases and the mass will be greater, if unfavorable, then D decreases and the mass of the aircraft will be less.

19) Balanced takeoff run P- available runway length, on which in case of failure of one engine at speed V 1 , the aircraft can complete both the takeoff run and the rejected takeoff.

20) Minimum evolutionary speed V min ev ≥ 1.05 V c in is the minimum speed at which there are enough rudders to balance the aircraft in level flight with one engine failing with a roll without slip.

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Airspeeds

What is airspeed?

Airspeed is the speed of the aircraft relative to the air. In other words: how fast the plane is moving relative to the air.

There are several measures of airspeed. Indicated (IAS) and true (TAS) speeds are most often used when flying in IVAO.

How to measure it?

The speed is displayed in flight on the speed indicators. It is connected to an air pressure receiver (APS) outside the aircraft and correlates the pressure of the incoming air flow with the pressure of the still air. The air pressure receiver is called a Pitot tube, it is located away from unstable air flows (away from screws and other nodes that cause air turbulence).

device

The main way to measure speed is to measure dynamic air pressure. This pressure corresponds to the speed of the air around the aircraft.

true airspeed,TrueAirspeed : TAS

The actual speed of the aircraft through the air
TAS is used for flight planning and navigation. It is used to calculate the estimated time of arrival and departure.
Note: see alsoGS(ground speed)

indicated airspeed,IndicatedAirspeed : IAS

This is the airspeed displayed on the instrument. This speed is identical to TAS under normal conditions (pressure 1013.25 hPa and 15° C)
IAS - speed for the safe control of aircraft. Stall speed and flap and landing gear limitation speeds are indicated airspeeds.

Effectheights

As altitude increases, pressure and temperature decrease. That is, at a constant airspeed in the set, the true speed will increase.

True airspeed cannot be measured, but can be calculated from airspeed, pressure, and temperature.

Aerodynamic effect

The only thing that matters to the pilot is how speed affects the behavior of the aircraft. The indicated speed best reflects the aerodynamic effect. However, as altitude changes, the error increases due to changes in air compression characteristics. Because of this effect, slightly more speed is required at high altitudes. The speed that takes this effect into account is the equivalent speed.

Equivalentspeed, Equivalent Airspeed:EAS

This speed is not used anywhere in the aircraft. It is used only by engineers to design aircraft components.

ground speed,GROUNDSPEED (GS)

Ground speed is the true wind speed and indicates the speed of the aircraft relative to the ground. It is displayed on the FMS or GPS and can be calculated from the true speed if the wind strength and direction are known.
This speed is needed to calculate the arrival time.

Example: Your TAS is 260 knots and headwind is 20 knots. Your ground speed is 260-20 = 240 knots. This means you are flying 4 miles per minute (240/60).

Numbermacha

Mach number is the speed of the aircraft relative to the speed of sound. The value is dimensionless and relative. It is calculated as the speed of an object relative to the medium divided by the speed of sound in that medium:

where is the Mach number; speed in this medium and the speed of sound in this medium.

Mach number is usually used above flight level 250 (7500 meters).

Other speeds

a) TAKEOFF:

V1 = Prior to reaching V1, the pilot may abort the takeoff. After V1, the pilot MUST take off.

VR = the speed at which the pilot, acting on the controls of the aircraft, increases the pitch and takes off.

V2 = safe speed to be reached in 10 meters.

b) ECHELON:

Va = The speed at which the aircraft will be fully controllable.

Vno = Maximum cruising speed.

Vne = Unreachable speed.

Vmo = Maximum allowable speed.

Mmo = Maximum allowable Mach number.

c) ENTRY and LANDING:

Vfe = Maximum speed with flaps extended.

Vlo = Maximum speed to use the chassis.

Vle = Maximum speed with landing gear extended.

Vs = Stall speed (with maximum weight)

Vso = Stall speed with landing gear and flaps extended (with maximum weight)

Vref = Landing speed = 1.3 x Vso

Minimum speed on clear wing = minimum speed with landing gear retracted, flaps and airbrakes, typically around 1.5 x Vso.

Minimum approach speed = Vref (see above), 1.3 x Vso.

Flight speed classification

According to the norms of the NLGS and the established practice, when piloting and navigating aircraft, the following flight speeds are distinguished: true airspeed, ground speed, vertical, relative true airspeed (number M), indicated speed, indicated ground speed, indicated speed .

true air v ist is the speed of the aircraft relative to the air.

ground speed w- this is the horizontal component of the speed of the aircraft relative to the Earth (Fig. 3.1).

It can be seen from the navigation triangle that the ground speed is equal to the geometric sum of the horizontal components v east and wind speed v V:

. (3.1)

Vertical speed v H is the vertical component of the aircraft's speed relative to the Earth, or the rate of change of true altitude

. (3.2)

Relative true airspeed is the true speed relative to the speed of sound at a given temperature. It's called a number M(Mach number):

. (3.3)

Indicated speed - the speed indicated by the speed indicator, calibrated by the difference between the total and static air pressures.

, (3.4)

Where P n is taken taking into account the compressibility of air.

The indicated ground speed is the indicated speed corrected for the instrumental error and the aerodynamic correction:

. (3.5)

Reference speed is the reference ground speed corrected for the compressibility correction associated with the difference in air pressure from standard sea level pressure:

. (3.6)

True airspeed is related to indicated airspeed as follows:

, (3.7)

Where ρ H - air density at flight altitude H; ρ 0 - standard air density at sea level.

Often, in the technical literature, no distinction is made between indicated and indicated speeds. In theoretical calculations, they mean the indicator speed. The indicated (indicator) speed is a purely aerobatic parameter. This parameter is especially responsibly and often used in such aircraft movement modes as takeoff, takeoff and landing. At each stage of the aircraft movement, the NLGS and ICAO standards assign characteristic values ​​of the indicated airspeed, which must be maintained from the safety condition. In this regard, there is a standard nomenclature of speeds:

Minimum evolutionary takeoff speed v min ER ( v MCG) is the speed at which, in the event of a sudden failure of a critical engine, it must be possible to control the aircraft using the aerodynamic controls to maintain the rectilinear movement of the aircraft (ICAO symbols are given in brackets);

Minimum Evolutionary Takeoff Speed v min EV ( v MCA) is the speed at which, in the event of a sudden failure of a critical engine, it must be possible to control the airplane using the aerodynamic controls to maintain the airplane in a straight line;

Minimum breakaway speed v min OTR ( v MU) is set for all aircraft configurations accepted for takeoff in the balance of balance range established by the Flight Operation Regulations (RLE). In this case, the angle of attack should not exceed the allowable value α add;

- v OTC ( v EF) is the speed at the time of engine failure;

Decision making speed v 1 is the take-off speed of the aircraft, at which both a safe termination and a safe continuation of the take-off are possible. The value of this speed is set in the AFM and must satisfy the following conditions: v 1 ≥ v min ER; v 1 ≤ v n.st;

Speed ​​at the time of lifting the nose landing gear v p.st - the speed of the beginning of the deflection of the steering wheel in the direction "toward" to increase the pitch angle on the takeoff run;

Safe Takeoff Speed v 2 must be at least: 1.2 v C1 in takeoff configuration; 1.1 v min EV; 1.08 vα add also in takeoff configuration;

Breakaway speed v OTR ( v LOF) is the speed of the aircraft at the time of separation of its main landing gear from the runway surface at the end of the takeoff roll;

Speed ​​at the time of the start of mechanization cleaning on takeoff v 3 ;

Takeoff flight speed v 4 . It must be at least 1.3 v C1 and 1.2 v min EV;

Minimum Evolutionary Approach Speed v min EP ( v MCL) is the speed at which, in the event of a sudden failure of a critical engine, it must be possible to control the aircraft using only aerodynamic controls;

Maximum approach speed v ZP max ;

Landing speed v ZP max ( v REF);

- v C( v S) is the stall speed, the minimum speed of the aircraft when braking up to the angle of attack α prev;

- v C1 ( v S 1) is the aircraft stall speed when the engines are running in idle mode;

- vα add ( v C y additional) speed at an acceptable angle of attack at n y=1;

- v max E - maximum operating speed. This speed must not be deliberately exceeded by the pilot in normal operation in all flight modes;

- v max max - design limit speed. It is set based on the possibility of its unintentional excess. v max max- v max ≥ 50 km/h. If this speed is exceeded, a catastrophic exception is not excluded.

3.2. Instrument for measuring indicator (indicated) speed

The IAS is used as a flight instrument to measure the aerodynamic forces acting on an aircraft in flight. It is known (2.18) that the aerodynamic lift force is determined by the formula

.

As the angle of attack increases α lift force increases up to its limit value. The greater the angle of attack, the less speed is needed to keep the aircraft in the air. As follows from paragraph 3.1, each flight mode corresponds to a certain minimum speed at which the aircraft can still stay in the air. For example, the condition for level flight is the equality of the weight of the aircraft and the lifting force

,

Where G is the weight of the aircraft. From here we find the speed of horizontal flight

.

The IAS is one of the most important flight instruments, it gives the pilot the opportunity to prevent the aircraft from falling at low speeds and destroying it at high speeds due to excessively large aerodynamic forces. According to the physical meaning, the indicated airspeed indicator does not measure the speed, but the difference between the total and static pressures (3.4), or the velocity head of the oncoming air, which depends on both the speed and the density of the air. Since it is more familiar and easier for the pilot to remember the characteristic values ​​of speed, and not the pressure of the velocity head, the pointer is calibrated in units of speed.

By definition (3.4), the indicator (instrument) speed is based on the manometric method, that is, on measuring the difference between the total and static pressure .

The relationship between velocity, total and static pressures is determined using the Bernoulli equation applied to the air flow perceived by the air pressure receiver (Fig. 3.2). At critical point 2, the air velocity drops to zero. Let us write this equation, without delving into its derivation, for the case of incompressible air:

, (3.8)

Where v 1 and v 2 – flow velocity in sections 1 and 2 in m/s; P 1 and P 2 - air pressure in sections 1 and 2 in kg / m 2; ρ 1 and ρ 2 - air density in sections 1 and 2 in kg s 2 /m 4.

Since section 1 is taken in an unperturbed medium, the velocity v 1 equals true airspeed v ist, pressure P 1 equals static pressure P Art. Pressure P 2 at the point of full braking is equal to the full pressure P n, since at this point the speed v 2 is zero. Considering that for an incompressible medium ρ 1 = ρ 2 = ρ , after the corresponding replacement in equation (3.8), we obtain

(3.9)

or
kg / m 2. (3.10)

Taking into account the compressibility of the air flow, equation (3.10) takes the form:

or finally
, (3.11)

Where
; q szh - velocity head, taking into account the compressibility of air.

Rice. 3.3. Pressure dependence P dyne from flow rate:

1 - without taking into account air compressibility; 2 - taking into account air compressibility

Figure 3.3 shows that taking into account the compressibility of the flow leads to an additional increase in dynamic pressure (line 2). In this case, the dependence of the dynamic pressure on the parameters of the air flow has the form:

, (3.12)

Where k is the ratio of heat capacities; g is the acceleration of gravity; R- gas constant, equal to 29.27 m / deg; T- temperature of the undisturbed atmosphere in o K. According to the formula (3.12), the indicator and true airspeed indicators are calibrated.

To calibrate the indicator speed indicator, values ​​are taken that correspond to normal conditions at sea level: R st = R o st \u003d 760 mm Hg. Art. (10332.276 kg / m 2), T = T o \u003d 288 o K ( t\u003d +15 ° C), R= 29.27 m/deg, mass density ρ o \u003d 0.124966 kg s 2 / m 4, k= 1.405. After that, it turns out that the indicator velocity according to formulas (3.11) and (3.12) depends only on the dynamic pressure R din. For practical use, there are standard tables that can be used to determine the value of dynamic pressure for each speed.

Special attention should be paid to the fact that the indications of the indicated airspeed indicator do not depend on the static pressure, and hence on the altitude of the aircraft. In this regard, they say that the indicator (as well as the sensor and signaling device) of the instrumental (instrumental) speed does not have a methodological error from a change in flight altitude. This is a valuable quality of a device that ensures flight safety regardless of altitude. It is important that there is always the required value of the velocity head at any height.

On fig. 3.4 shows a schematic diagram of an airspeed indicator with separate pressure receivers R n and R Art. Full pressure R n = R d + R st enters the sealed cavity of the manometric box 5 from the receiver 7 through the pneumatic line 6. Pressure enters the sealed cavity of the body 3 from the receiver 1 through the pneumatic line 2 R Art. Under the influence of pressure difference R P - R st = R d + R st - R st = R e the membrane of the manometric box bends and turns the pointer relative to the indicator - scale 4.

Rice. 3.4. Schematic diagram of the indicated speed indicator: 1 - static pressure receiver R st; 2 - pneumatic line of static pressure; 3 - body; 4 - indicator; 5 - manometric box; 6 – full pressure pneumatic line; 7 - full pressure receiver R P

Rice. 3.5. Structural diagram of the indicated speed indicator: 1 - pressure receiver R n and R st; 2 - pneumatic pipeline R P; 3 - pneumatic pipeline R st; 4 - settling tanks-filters of the channel R P; 5 - settling tanks-filters of the channel R st; 6 - the cavity of the box; 7 - body cavity; 8 - conditional link in the formation of dynamic pressure R d; 9 - decision device; 10 - indicator

Figure 3.5 shows a block diagram of the indicated airspeed indicator, compiled according to its concept diagram (Figure 3.4). Let us consider in more detail the role of each link in the operation of the indicator speed indicator.

Full pressure receiver

For the indicator speed indicator to work according to the principle of its operation, it is necessary to perceive the total and static pressure in flight. In the practice of aircraft instrumentation, the use of separate receivers for total and static pressures takes place (Fig. 3.4). The pressures must be perceived accurately, since the dynamic pressure depends on the square of the speed.

The full pressure receiver (PPD) is designed to perceive only the full pressure of the oncoming air flow. The concept of "total pressure" refers to the pressure per unit surface of a body whose plane is perpendicular to the direction of the oncoming flow. For PPD, a cylindrical body is used, in the center of which a through hole is made.

From Figures 3.6 and 3.7 it can be seen that the total deceleration of the oncoming air flow will be only at the point A. If in the cylinder around the point A make a hole, then a pressure equal to the total pressure will be established along its cavity R n = R st + R e. Like any tool, PPD has a perception error R n, associated with the imperfection of its design.

From the very definition of total pressure, it follows that the best location of the PPD relative to the air flow is when the cross-sectional plane of the inlet of the receiver is perpendicular to the velocity vector. In this case, the receiver error will be caused only by flow losses in the channel cavity R n (Fig. 3.8). This installation condition is equivalent to when the longitudinal axis of the PPD receiver coincides with the direction of the air flow.

But even in this case, the receiver has an error of the order of 2%, which is defined as the ratio of the absolute value of the error Δ R n to velocity head 0.5 ρ v 2 .

Under these conditions, formula (3.11) can be rewritten as

, (3.13)

Where ξ is the receiver coefficient at α = β = 0. If the setting of the SPD is such that α ≠ 0, β ≠ 0, then there are additional angular errors Δ R n = ± Δ R P f(α ) and Δ R n = ∆ R P f(β ). The next reason for the appearance of the PPD error is the bevel of the air flow at the location of the receiver on board the aircraft. This error is normalized by the NLGS within no more than 10 km/h or 3% (whichever is greater) over the entire speed measurement range. Due to the choice of the installation site on board the aircraft, due to design techniques and calibration in wind tunnels, the PPD error can be reduced to ± (0.005 - 0.01) q.

Speed ​​range from 40 to 1100 km/h; weight 0.17 kg; error in the speed range up to 150 km/h no more than ± 0.05 q at angles α = β = ± 25 o; error at speeds over 150 km/h and angles α = β = ± 20 o no more than ± 0.025 q; heating with direct current up to 135 W.

Rice. 3.9. The design of the receiver PPD-4: 1 - tip; 2 - drainage hole;

3 - heating element; 4 - hole; 5 - cheek; 6 - base; 7 - socket; 8 - fork; 9 - wire; 10 - fitting

Rice. 3.10. Appearance of the total pressure receiver PPD-9V

Static pressure receiver

Static pressure is the pressure that would exist at a given point in the medium unperturbed by the device if the device were moving at the speed of the flow. The static pressure in a medium at rest is called barometric or atmospheric pressure and is measured with a barometer. It is measured as absolute pressure measured from absolute zero pressure. For measuring static pressure R st, a device of such a design is needed that would not distort the flow at the point under study. When measuring pressure R st the device moves relative to the air, and this, according to the laws of aerodynamics, leads to air disturbance. In this case, the shape of the device - receiver R st plays a major role on the measurement accuracy. The measured pressure will be the sum of the pressure in the flow unperturbed by the device and the additional pressure caused by the flow around the device, and depends on its shape. The flow conditions around the instrument may be such that the measured pressure may be greater or less than its true value (Fig. 3.11).

Rice. 3.11. Distribution of the pressure coefficient for a typical subsonic distribution along the line of the aircraft fuselage: 1 - only along the free fuselage; 2 - along the fuselage along with planes and tail

Most frequently measured R st applies a static probe (static hook). It is a hollow cylindrical tube with a diameter d with a streamlined closed toe.

On the side surface of the tube there are holes of small diameter. To improve the measurement accuracy in the device, increase the distance l 1 from the receiving holes to the toe and the other way - l 2 to the holder. The following ratios are recommended: l 1 = 3d, l 2 = 8δ .

In aviation, the role of a hollow cylindrical tube is often used by the aircraft fuselage itself (at subsonic), in which receiving holes are made (Fig. 3.13).

For convenience and reliability of perception R st instead of holes in the fuselage, a standard plate with holes is used. Together with the body, it forms a device for the perception of static pressure (Fig. 3.14). On the fuselage, such places are chosen for installing the tile receiver, where the smallest deviations of line 2 in Fig. 3.11 from the middle line 0-0. The receiver plate is mounted on the aircraft flush with the skin.

Rice. 3.15. Appearance of the PDS-V3 plated static pressure receiver R st up to 450 km/h; weight 0.25 kg; heating with DC voltage 27 V at power up to 60 W

In addition to the considered receivers R n and R st widely used in aviation have found combined receivers, which are called PVD. This device combines two devices: receivers R n and R st (Fig. 3.16). Separate receivers are mainly used at subsonic flight speeds. At supersonic flight speeds, the flow around the fuselage is so complex and unpredictable that it is impossible to find places to install pressure receivers.

Rice. 3.16. Schematic diagram of the receiver type PVD: 1 - full pressure chamber; 2 - opening of the static pressure chamber; 3 – static pressure chamber; 4 - static pressure pipeline; 5 - full pressure pipeline

On supersonic aircraft, the HPH is carried out with the help of a rod into the undisturbed space in front of the aircraft. In the same way, LDPE is installed on a helicopter.

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