How is the speed of a plane calculated when it’s on its cruising altitude?
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There are multiple speeds.
There’s indicated airspeed, which is the speed on your dials.
There’s calibrated airspeed, which corrects for .. you guessed it. Instrument calibration.
There’s equivalent airspeed, which is calibrated airspeed plus math because air does funny things when you go *really fast*.
Then there’s true airspeed, which is equivalent airspeed corrected for temperature and altitude.
All the “airspeeds” measure your speed through the air. The air is usually also moving.
Then there’s ground speed, which is your true airspeed adjusted for the movement of the mass of air you’re flying in. It measures… your speed over the ground.
There are multiple speeds.
There’s indicated airspeed, which is the speed on your dials.
There’s calibrated airspeed, which corrects for .. you guessed it. Instrument calibration.
There’s equivalent airspeed, which is calibrated airspeed plus math because air does funny things when you go *really fast*.
Then there’s true airspeed, which is equivalent airspeed corrected for temperature and altitude.
All the “airspeeds” measure your speed through the air. The air is usually also moving.
Then there’s ground speed, which is your true airspeed adjusted for the movement of the mass of air you’re flying in. It measures… your speed over the ground.
There are multiple speeds.
There’s indicated airspeed, which is the speed on your dials.
There’s calibrated airspeed, which corrects for .. you guessed it. Instrument calibration.
There’s equivalent airspeed, which is calibrated airspeed plus math because air does funny things when you go *really fast*.
Then there’s true airspeed, which is equivalent airspeed corrected for temperature and altitude.
All the “airspeeds” measure your speed through the air. The air is usually also moving.
Then there’s ground speed, which is your true airspeed adjusted for the movement of the mass of air you’re flying in. It measures… your speed over the ground.
At least on the small planes I’ve flown, many years ago. it’s through what’s called a pitot tube. It’s an L-shaped tube that comes down from the wing and points forward in the direction of travel, and as the air flows past the wing the pitot tube captures some of that airflow and measures the speed. If the pitot tube freezes and air can’t get in, then your airspeed indicator on the instrument panel will not function.
At least on the small planes I’ve flown, many years ago. it’s through what’s called a pitot tube. It’s an L-shaped tube that comes down from the wing and points forward in the direction of travel, and as the air flows past the wing the pitot tube captures some of that airflow and measures the speed. If the pitot tube freezes and air can’t get in, then your airspeed indicator on the instrument panel will not function.
At least on the small planes I’ve flown, many years ago. it’s through what’s called a pitot tube. It’s an L-shaped tube that comes down from the wing and points forward in the direction of travel, and as the air flows past the wing the pitot tube captures some of that airflow and measures the speed. If the pitot tube freezes and air can’t get in, then your airspeed indicator on the instrument panel will not function.
Do you mean how is it measured?
A computer, appropriately called an Air Data Computer, takes in information from sensors outside the aircraft and calculates the plane’s true airspeed. It’s typically the difference between dynamic pressure (what you would feel against your hand if you stuck it out the window) and static pressure, which is what you’d feel standing still. This may seem trivial but keep in mind that at altitude the static pressure is much much less than down at sea level.
As far as how we describe our speed, there are a few ways. There’s indicated airspeed, which is what the “speedometer” shows. Then there’s true airspeed, which is how fast the plane is actually travelling through the air. And then there’s also ground speed. Which is how fast the plane is moving over the ground. This is simply the true airspeed plus or minus the tailwind/headwind.
If you’re asking why indicated airspeed and true airspeed are not the same it’s a rather long explanation. But it’s essentially because indicated airspeed is a function of dynamic pressure and at altitude the dynamic pressure is much less (air molecules are farther apart). But this speed is still very important to pilots because it’s a measurement of what the airplane is “feeling “.
The last airspeed we use is Mach number. This is just plane’s speed divided by the speed of sound. Airliners typically fly around Mach 0.75-0.85. Our Mach speed is important because as you start getting close to Mach 1 weird things start happening to the airflow over the wing.
Do you mean how is it measured?
A computer, appropriately called an Air Data Computer, takes in information from sensors outside the aircraft and calculates the plane’s true airspeed. It’s typically the difference between dynamic pressure (what you would feel against your hand if you stuck it out the window) and static pressure, which is what you’d feel standing still. This may seem trivial but keep in mind that at altitude the static pressure is much much less than down at sea level.
As far as how we describe our speed, there are a few ways. There’s indicated airspeed, which is what the “speedometer” shows. Then there’s true airspeed, which is how fast the plane is actually travelling through the air. And then there’s also ground speed. Which is how fast the plane is moving over the ground. This is simply the true airspeed plus or minus the tailwind/headwind.
If you’re asking why indicated airspeed and true airspeed are not the same it’s a rather long explanation. But it’s essentially because indicated airspeed is a function of dynamic pressure and at altitude the dynamic pressure is much less (air molecules are farther apart). But this speed is still very important to pilots because it’s a measurement of what the airplane is “feeling “.
The last airspeed we use is Mach number. This is just plane’s speed divided by the speed of sound. Airliners typically fly around Mach 0.75-0.85. Our Mach speed is important because as you start getting close to Mach 1 weird things start happening to the airflow over the wing.
Do you mean how is it measured?
A computer, appropriately called an Air Data Computer, takes in information from sensors outside the aircraft and calculates the plane’s true airspeed. It’s typically the difference between dynamic pressure (what you would feel against your hand if you stuck it out the window) and static pressure, which is what you’d feel standing still. This may seem trivial but keep in mind that at altitude the static pressure is much much less than down at sea level.
As far as how we describe our speed, there are a few ways. There’s indicated airspeed, which is what the “speedometer” shows. Then there’s true airspeed, which is how fast the plane is actually travelling through the air. And then there’s also ground speed. Which is how fast the plane is moving over the ground. This is simply the true airspeed plus or minus the tailwind/headwind.
If you’re asking why indicated airspeed and true airspeed are not the same it’s a rather long explanation. But it’s essentially because indicated airspeed is a function of dynamic pressure and at altitude the dynamic pressure is much less (air molecules are farther apart). But this speed is still very important to pilots because it’s a measurement of what the airplane is “feeling “.
The last airspeed we use is Mach number. This is just plane’s speed divided by the speed of sound. Airliners typically fly around Mach 0.75-0.85. Our Mach speed is important because as you start getting close to Mach 1 weird things start happening to the airflow over the wing.
Ground speed: GPS coordinates
Indicated air speed: The most common way is a pitot-static system. The plane will have one or more “static ports” with calm air from outside and one or more “pitot tubes” where outside air comes rushing into a chamber at full speed, creating a pocket of higher pressure. (It’s literally called “ram air pressure” because the air is ramming itself in.) Using the difference between static air pressure and ram air pressure, the plane’s computers can calculate the speed of the ram air – which is also the plane’s air speed.
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