15 knots is how many kilometers per hour. How much is one sea knot in terms of speed equivalent in kilometers? Example of calculating ship speed

) - unit of speed. Equal to the speed of uniform motion at which a body travels a distance of one nautical mile in one hour. It is used in maritime and aviation practice, in meteorology, and is the basic unit of speed in navigation.

By international definition, one knot is equal to 1852 m/h exactly or 0.51444... m/s. This unit of measurement, although non-systemic, is allowed for use along with units of the International System of Units (SI). In the Russian Federation, the unit is approved for use as an off-system unit without a time limit with the scope of application “marine navigation”. The unit is included in the All-Russian Classifier of Units of Measurement.

The prevalence of the knot as a unit of measurement is associated with the significant convenience of its use in navigation calculations: a ship moving at a speed of 1 knot along the meridian passes one arc minute of geographic latitude in one hour.

The origin of the name is related to the principle of using a manual sector log, which in its simplest form was a plank tied to a long thin cable (lagline) in such a way that when thrown overboard of a moving vessel, it would be braked by the water. Knots were tied on the laglin at equal distances from each other; the distance was selected such that the number of knots on the lagline being etched overboard, escaping from the lag view and passing through the measuring hand in a certain time, was numerically equal to the speed of the vessel, expressed in nautical miles per hour.

A knot is an independent unit of speed. To say: “The ship is moving at a speed of 36 knots per hour” is incorrect. The fallacy of such an expression is illustrated in the story “The Flying Dutchman” by L. S. Sobolev, an excerpt from which is given below:

Tell me, captain, what is our speed? - Raising his glasses from his notebook, the guest asked again.
Guzhevoy already opened his mouth to answer with his usual wit, that there were six knots per hour - in the first, and in the second they didn’t pull even three, but Piychik warned him:
Allowed: full speed, twelve knots.

- Leonid Sergeevich Sobolev. Stories of Captain 2nd Rank V. L. Kirdyaga, heard from him during the “Great Seat”

Knot and nautical mile are widely used in maritime and air transport. The knot is the only widely used unit of speed that has its own name. Decimal prefixes (kilo-, milli-, etc.), which are used to form multiples and submultiples, are not used with the “knot” unit.

Knots and miles per hour should not be confused. A knot is one nautical (or nautical) mile (1852 meters) per hour, and "mile per hour" (English mph, miles per hour), widely used in Great Britain and North America, is a statute mile (1609 meters) in hour.

Before the introduction of the international knot, similar knot definitions were also used, based on different definitions of the nautical mile. In the USA, until 1952, a knot based on the American nautical mile (1852.249 m) was used. In Great Britain until 1970 (as well as in the countries of the British Commonwealth), a unit based on the British or Admiralty nautical mile (1852.184 m) was used. The difference between both definitions and the modern definition of a node is about 0.01% and is insignificant in almost all practical cases.

There is a simple mnemonic for quickly mentally converting knots to kilometers per hour: “multiply by two and subtract 10 percent.” For example, speed 15 knots, 15×2 = 30 km/h, subtract 10% = 3 km/h, we get 27 km/h. The rule gives values with an error of less than 3%. To recalculate km/h → nodes, the reverse algorithm is used: the speed in km/h is divided by 2 and 10% is added to the resulting value. For example, 20 km/h → 10 knots → 11 knots(the exact value is 10.799136... nodes).

Notes

Regulations on units of quantities allowed for use in the Russian Federation. Approved by Decree of the Government of the Russian Federation No. 879 of October 31, 2009.
The international designation “kn” (from the English “knot”) is established by the ISO 80000-3 standard.
Not recommended as it is the same as the international designation for kiloton.
Dengub V. M., Smirnov V. G. Units of quantities. Dictionary-reference book. - M.: Standards Publishing House, 1990. - P. 117. - 240 p. - ISBN 5-7050-0118-5.
Stanyukovich K. M. .
OKEY 327 - Knot (mph).
Traditional measurement times varied across different navies: 15 seconds, 28 seconds, 30 seconds or 1 minute. Time was recorded using

Nautical mile - the average arc length of one minute of the earth's meridian.
Arc length of one minute of the earth's meridian 1" = 1852.23 - 9.34 cos 2φ,
where φ is the latitude of the vessel in degrees.
The length of a nautical mile adopted in Russia is 1852.00 meters. Approximately 6080 feet.
Why 1852? If we take the shape of the Earth as a sphere, then the circumference along the meridian will be 40,000,000 meters. Hence 40,000,000 m: 360° = 40,000,000: 360*60" = 40,000,000: 21,600" = 1851, 85 meters in 1".

Example: distance to port 48 miles.
Or: 43 miles 8 cables. Or: 43.8 miles.

Cable - one tenth of a nautical mile, rounded equal to 185 meters. 1 mile = 10 kbt.

Example:the distance to the ship is 14 cables.

Knot - one nautical mile per hour (1.852 km/h) or 0.514 m/s (meters per second).

Example:ship speed 23 knots.

Knot is a linear speed of 1 nautical mile per hour. The term “knot” appeared in the era of sailing, when the speed of a ship was measured using the so-called sector lag - a sector-shaped wooden shield released from the stern of the ship into the water on a lagline (braided rope). Such a sector was held by the extensions of the lagline at three points, due to which it maintained a perpendicular position in the water to the direction of the vessel's progress. Since the sector is slowed down by water, the lagline was etched approximately at the speed of the ship. If the lagline was divided into sections of 50.7 feet with the help of knots, that is, equal to 1\120 miles (6080\50.7 = 120), then at a speed of 1 knot the lagline will be etched in 1 minute or 1\60 hours by 1/60 miles (2 knots), and in 0.5 minutes - by 1 knot. If, for example, 9 knots were etched in 0.5 minutes, then it was considered that the ship was moving at a speed of 9 knots.
On English maps they are also used

Sometimes the notation is also used kt) - unit of speed. Equal to the speed of uniform motion at which a body travels a distance of one nautical mile in one hour. It is used in maritime and aviation practice, in meteorology, and is the basic unit of speed in navigation.

Tell me, captain, what is our speed? - Raising his glasses from his notebook, the guest asked again.
Guzhevoy already opened his mouth to answer with his usual wit, that there were six knots per hour - in the first, and in the second they didn’t pull even three, but Piychik warned him:
Allowed: full speed, twelve knots.

- Leonid Sergeevich Sobolev. Stories of Captain 2nd Rank V. L. Kirdyaga, heard from him during the “Great Seat”

Notes

Regulations on units of quantities allowed for use in the Russian Federation. Approved by Decree of the Government of the Russian Federation No. 879 of October 31, 2009.
The international designation “kn” (from the English “knot”) is established by the ISO 80000-3 standard.
Not recommended as it is the same as the international designation for kiloton.
Dengub V. M., Smirnov V. G. Units of quantities. Dictionary-reference book. - M.: Standards Publishing House, 1990. - P. 117. - 240 p. - ISBN 5-7050-0118-5.

Used in maritime and aviation practice.

By international definition, one knot is equal to 1.852 km/h (1 nautical mile per hour) or 0.514 m/s. This unit of measurement, although non-systemic, is allowed for use along with units of the International System of Units (SI). In the Russian Federation, the node is approved for use as an off-system unit without a time limit with the scope of application “maritime navigation”.

The origin of the name is related to the principle of using sector lag. The speed of the vessel was determined as the number of knots on the line (thin cable) that passed through the hand of the measurer in a certain time (usually 15 seconds or 1 minute). In this case, the distance between adjacent nodes on the line and the measurement time were selected in such a way that this amount was numerically equal to the speed of the vessel, expressed in nautical miles per hour. A knot is an independent unit of speed. To say: “The ship is sailing at a speed of 36 knots per hour” is incorrect. The absurdity of such an expression is very well described in the story of L.S. Sobolev “The Flying Dutchman”, an excerpt from which is given below.

Tell me, captain, what is our speed? - Raising his glasses from his notebook, the guest asked again.
Guzhevoy had already opened his mouth to answer with his usual wit that there were six knots per hour - in the first, and in the second they didn’t pull even three, but Piychik warned him:
Allowed: full speed, twelve knots.

The lag cable, released while moving from the stern, broke into knots at a distance of 1/120 of a mile (50 feet). By counting the number of knots that travel in half a minute (1/120 of an hour), you can find out the speed in nautical miles per hour. It follows that the expression “30 knots per hour” is clearly meaningless: it turns out that the ship, instead of a decent speed of 56 km/h, drags 1500 feet (~460 m) per hour, which is incorrect.

Knot and nautical mile are widely used in maritime and air transport.

Knots and miles per hour should not be confused. A knot is one nautical (or nautical) mile (1852 meters) per hour, and "mile per hour" (mph, miles pro hour), widely used in Great Britain and North America, is a statute mile (1609 meters) in hour.

Encyclopedic YouTube

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✪ Mach number

✪ Combination of units of measurement -ours- and -imperial-

✪ How to convert kilometers per hour to meters per second?

Subtitles

You may have heard something like: “the speed of a certain aircraft is Mach 2.” Or in some science fiction movie or maybe an action movie you heard something like: “we will go to Mach 1 or 8.” Surely you understood from the context that we are talking about speed. These numbers characterize a certain speed. If you think so, you are absolutely right. And these numbers represent multipliers, or parts of the speed of sound in a particular medium. If the Mach number is known to be 2, this tells us that the speed is twice the speed of sound in a certain environment under certain conditions. So, I will repeat, if you know that the Mach number is 2, it means that the speed is twice the speed of sound in a certain environment under certain conditions. These are important clarifications because the speed of sound is not always the same. The speed of sound depends on where it travels, whether it is in air or perhaps water, and even whether it depends on the composition of the air. And even if sound propagates in air of a certain composition, a mixture of gases, its speed also depends on temperature. So if you're at sea level and the temperature is 20 degrees Celsius, the speed of sound is 300. So sea level, I'll take a different color, blue for sea level, here the speed of sound is about 340 meters per second. So, the speed of sound is 340 m/s. At 20 degrees Celsius, a comfortable temperature at sea level, the speed of sound is about 760 miles per hour. And if the temperature drops, the same happens with the speed of sound. If the temperature drops, so does the speed of sound. We'll write this down. Wonderful. If the temperature increases, the speed of sound also increases. So if you are told that something is moving at Mach 2, they mean that it is moving twice the speed of sound in a certain environment. Usually it means something moving in the air. And the speed of sound for a certain temperature. If we are talking about a high altitude, and usually, in order to move at such a speed, you have to rise quite high, where the air is less dense. And the temperature there can be well below 20 degrees Celsius. Now, if something is moving at Mach 2, does that mean its speed is 680 meters per second or 1520 miles per hour? And of course, when air speed is reported, it means relative to the air. And the answer will be no. Surely this speed will be a little less, because at such an altitude the speed of sound will also be lower. There are speed records on earth that allow us to talk about speed in terms of Mach number. In such cases, the Mach number is equivalent to 760 miles per hour or 340 meters per second. By the way, you are probably wondering whose portrait this is, copied from Wikipedia? This is Ernst Mach. The one after whom the Mach number is named. Ernst Mach - Austrian physicist and philosopher. He was researching shock waves, sound waves and things like that. So the Mach number is named after him. Get acquainted. Subtitles by the Amara.org community

Let's start with the basics: the speeds of most modern aircraft are measured in knots. A knot is a nautical mile (1.852 km) per hour. This is due to navigational tasks that have come since the times of sailors. A nautical mile is a minute of latitude.

Indicated airspeed is displayed in the left column on the main flight display (PFD), and takeoff speeds V1, Vr and V2 are also displayed here. The navigation display shows TAS (true speed) and GS speeds. Let's look at each speed separately.

First, let's look at the instrument speed (IAS). If you ask the pilot during a flight, “What is our speed?” - it will first point you to the speed indicator to the left of the attitude indicator on the main flight display (PFD). When piloting, this is perhaps the most important speed; it characterizes the load-bearing properties of the glider at the current moment, regardless of the flight altitude. It is used to calculate takeoff, landing, V-stall and other key aircraft speeds.

How is indicated speed determined? Air pressure receivers (APRs), also known as Pitot tubes, are installed on airplanes. Based on the dynamic pressure measured with their help, the instrument speed is calculated.

An important point is that the formula for calculating the indicated speed uses a constant, standard pressure at sea level. Do you remember that as altitude increases, pressure changes? Accordingly, the indicated speed coincides with the speed relative to the ground only at the surface.

Another interesting fact: what image comes to mind when you hear about aviation pioneers? A brown leather jacket, a helmet with goggles and a long white silk flowing scarf. According to some legends, the scarf was the first primitive indicator of instrument speed!

Now let's look at the top left corner of the navigation display. Our speed relative to the ground GS (Ground Speed) is displayed here. This is the same speed that is reported to passengers during the flight. It is determined primarily by data from satellite systems such as GPS. It is also used for control during taxiing, since at low speeds the pitot tubes do not create sufficient dynamic pressure to determine IAS.

A little to the right TAS (True Air Speed) is the true airspeed, the speed relative to the air surrounding the aircraft. All photographs were taken at approximately the same point in time. As you can see, the speeds vary significantly.

The IAS indicated speed is just under 340 knots. True airspeed TAS is 405 knots. Speed relative to the surface GS - 389. Now, I think you understand why they are different.

I also want to note the Mach number. Simplifying a little, this is the speed of a body relative to the speed of sound in a given medium. It is displayed under the indicated speed column and in our situation is 0.637.

Now let's discuss takeoff speeds. The three main takeoff speeds V1, Vr and V2, designations are standard for all aircraft that have more than one engine, from the little Beechcraft 76 to the giant Airbus A380, they are always located in this sequence. Let's imagine that our A320 is on the runway, the checklist has been completed, the controller's permission has been received, and we are completely ready for takeoff.

You move the engine controls to 40%, make sure the rpm is stable, and set the takeoff mode. The first speed to be reached will be V1 (148 knots in our conditions). This is the speed of decision making, in other words, after reaching V1, the takeoff can no longer be interrupted, including in the event of a serious failure. Even if you have an engine failure and V1 has already been reached, you must continue to take off. Before V1 in this situation, you initiate the aborted takeoff procedure, engage reverse, automatic braking is activated, spoilers are released, and you manage to stop before the end of the runway.

But everything is fine with us, the engines are working normally and, after V1, the pilot takes his hand off the engine control levers. Vr speed (rotate speed, 149 knots) is approaching. At this speed, the flying pilot pulls the control wheel (in our case, the sidestick) towards himself and lifts the nose landing gear into the air.

At the same moment V2 arrived, in our situation Vr and V2 were calculated the same, but often V2 exceeds Vr. V2 - safe speed. In the event of failure of one of the engines, it will be V2 that will be supported; it guarantees a safe climb gradient. But, as you remember, everything is fine with us, the SRS mode is active, and the speed is V2+10 knots.

On the PFD during takeoff, V1 is indicated by a blue triangle, a magenta dot by Vr, and a magenta triangle by V2.

So, you have learned what takeoff speeds are and what they are eaten with, and now let’s find out how to prepare them, and what they depend on. We've now got our beautiful A320 in the air, but let's rewind the clock a little.

Let's imagine that we are preparing for departure, and it is time to calculate the speeds V1, Vr and V2. It's the 21st century, and the miracles of progress have given us an electronic flight briefcase (EFB - a specially trained iPad with the necessary set of software). What exactly information needs to be added to this briefcase so that the magic of ones and zeros can calculate our speeds? First of all, the length of the runway. You and I are preparing to take off from runway 14, right, of the capital's Domodedovo Airport. Its length is 3500 meters.

The moment of truth is coming. We enter our take-off weight and balance. We are deciding whether we can even take off from this runway, or whether we will have to leave a couple of hundred bottles from duty free and the four most obese passengers on earth :)

Since 3500 meters is more than enough for takeoff, we continue to enter data. Next in line are Airfield elevation above sea level, Wind component, Air temperature, Runway condition (wet/dry), Takeoff thrust, Flap position, Use of packs (air conditioning system) and anti-icing systems. Voila, the speeds are ready, all that remains is to add them to the MCDU.

Okay, we discussed calculating speeds using an electronic flight bag, but if you threw too many angry birds before the flight or, which is completely shameful for a pilot, played with tanks and discharged your miracle device? What if you are a representative of the school of obscurantism and deny progress? You are about to embark on a fascinating quest into the world of documents with scary names and the tables and graphs they contain.

First, we check whether we will take off from the selected runway: we open a graph in which the necessary variables are laid out along the axes. We move our finger to the intersection, and if the desired value is inside the graph, the attempt promises to be successful.

Next, take the next document and begin to calculate V1 Vr and V2. Based on the weight and the selected configuration, we obtain the speed values. Moving from plate to plate, we make adjustments, depending on the cell we add or subtract several nodes.

And so on over and over again until you get all the values, and there are many of them. Just like in first grade - he moved his finger and read the symbol. Very entertaining.

There is very little left: take off, turn on the autopilot at a thousand feet and wait just a little longer. And then the girls will bring a roller-coaster with food and you can immerse yourself in school memories. And the Airbus itself flies well, the main thing is not to interfere with it.

But we were daydreaming again. Meanwhile, we took off from the ground, maintained a speed of V2+10 knots and even managed to retract the landing gear so that they would not freeze. It's cold at the top, remember? We will gain altitude without applying noise reduction procedures, let everyone know that we have taken off! Once again, the old ladies on the upper floors will begin to vigorously cross themselves, and the children will joyfully point their fingers into the sky at our liner shining in the sun.

Before we could blink an eye, we reached an altitude of 1500 feet. It's time to put the Motor Control levers into Climb mode. The nose drops lower, and we begin to accelerate to S-speed, at which we remove the mechanization (Flaps 0), the next speed limit is 250 knots. 10,000 feet, the nose drops even lower, the speed continues to increase faster and the altitude slower. We turn off the Landing Lights, and the most impatient ones already have their hand ready to turn off the “fasten your seat belts” sign.

Top of climb, the specified flight level has been reached, the plane is leveling off, we are moving at cruising speed. It's time to replenish your calories!

Dinner at an altitude of several kilometers with panoramic views of the surrounding area is wonderful. Yes, the food is not Michelin star worthy, but they will pay your bill! But all good things, as we know, tend to come to an end, so it’s time for us to decline. We lower the nose and begin our descent. After 10,000 feet the speed drops to 250 knots and we continue to decrease altitude.

It's time to move into the approach phase. Using the magic of the airbus (which itself calculated all the speeds), we slow down to Green dot speed (clean wing speed). Flying at this speed is as economical as possible for us, but you remember that everything good has the property...

We lower the flaps to the first position, the speed is reduced to S-speed. Next - flaps 2 and smoothly reach F-speed. Flaps 3 and finally full flaps, slowing down to Vapp. Vapp - minimum speed (VLS), but adjusted for wind and gusts (minimum 5 maximum 15 knots).

1000 feet, we check that the stabilized approach criteria are met, and if everything is normal, we continue our descent. Before touching down, the plane will demonstrate its attitude towards you by proclaiming “Retard! Retard! Retard!” (If you are not good at English-language name-calling, you can use the urbandictionary online dictionary). Set the throttle to idle and after a moment gently touch the runway.