How Fast Does Plane Go to Take Off

How Fast Does Plane Go to Take Off: A Quick Guide

How Fast Does Plane Go to Take Off?

Have you ever wondered how fast does plane go to take off? If you are a frequent flyer or an aviation enthusiast, you might be curious about the speed and physics behind this amazing feat of engineering.

In this article, we will explain the factors that affect the takeoff speed of different types of planes, and how you can calculate it using some simple formulas.

What is Takeoff Speed?

Takeoff speed is the minimum speed that an airplane needs to generate enough lift to overcome its weight and drag, and become airborne. Lift is the upward force that is created when air flows over and under the wings of the plane. The amount of lift depends on the shape and size of the wings, the angle at which they meet the airflow, the density of the air, and the speed of the plane.

The takeoff speed varies for each airplane model, depending on its weight, wing design, engine power, and other factors. Generally, smaller planes have lower takeoff speeds than larger ones, and jet planes have higher takeoff speeds than propeller planes. For example, a Cessna 172, a popular small plane, has a typical takeoff speed of about 55 knots (63 mph or 102 km/h), while a Boeing 747, a large jet plane, has a typical takeoff speed of about 180 knots (207 mph or 333 km/h).

What Factors Affect Takeoff Speed?

There are many factors that affect the takeoff speed of an airplane, both internal and external. Some of the most important ones are:

  • Weight: The heavier the plane is, the more lift it needs to take off, and therefore the higher the speed it needs to reach. Weight depends on the fuel load, passengers, cargo, and equipment on board. As a rule of thumb, a 10% increase in weight increases the takeoff speed by 5%.
  • Altitude: The higher the altitude of the airport, the less dense the air is, and therefore the less lift it provides. This means that planes need to go faster to take off at higher altitudes than at lower ones. For example, Denver International Airport in Colorado has an elevation of 5,430 feet (1,655 meters) above sea level, and therefore planes need about 10% more speed to take off there than at sea level.
  • Temperature: The hotter the air is, the less dense it is, and therefore the less lift it provides. This means that planes need to go faster to take off in hot weather than in cold weather. For example, Phoenix Sky Harbor International Airport in Arizona has an average high temperature of 106°F (41°C) in July, and therefore planes need about 7% more speed to take off there than at standard temperature (59°F or 15°C).
  • Wind: The wind can either help or hinder the takeoff speed of a plane, depending on its direction and speed. A headwind (wind blowing against the direction of travel) increases the airflow over the wings and therefore increases the lift. This means that planes need less speed to take off with a headwind than with no wind. A tailwind (wind blowing in the same direction as travel) decreases the airflow over the wings and therefore decreases the lift. This means that planes need more speed to take off with a tailwind than with no wind. A crosswind (wind blowing perpendicular to the direction of travel) has little effect on the lift, but can make steering and balancing more difficult during takeoff.
  • Runway: The length, slope, surface, and condition of the runway also affect the takeoff speed of a plane. A longer runway allows more time and distance for acceleration and deceleration. A sloped runway can either increase or decrease the effective gravity force on the plane, depending on whether it is uphill or downhill. A smooth and dry runway reduces friction and drag on the wheels. A rough or wet runway increases friction and drag on the wheels, and can also reduce traction and braking.

How to Calculate Takeoff Speed?

There are different methods to calculate the takeoff speed of an airplane, depending on its type and model. Some of them are:

  • Group Rating System: This is a simple method that assigns a group number to each airplane model based on its weight and wing area. The group number ranges from 1 to 6 for light airplanes (up to 12,500 pounds or 5,670 kilograms), and from A to F for heavy airplanes (above 12,500 pounds or 5,670 kilograms). The group number determines a reference takeoff speed that can be adjusted for altitude and temperature using correction tables. This method is conservative and easy to use, but not very accurate for specific conditions.
  • P-Charts: These are graphs that show how different factors affect the takeoff performance of an airplane model. They usually include curves for different weights, altitudes, temperatures, wind speeds and directions, and runway slopes and surfaces. To use this method, you need to find the intersection of the curves that correspond to your conditions, and read the takeoff speed from the horizontal axis. This method is more precise and detailed than the group rating system, but requires more time and data to use.
  • Approved Aircraft Flight Manual Data: This is the most accurate and reliable method to calculate the takeoff speed of an airplane model, as it is based on the data and tests provided by the manufacturer. The Aircraft Flight Manual (AFM) contains tables and charts that show the takeoff performance of the airplane for different configurations, weights, altitudes, temperatures, wind speeds and directions, and runway slopes and surfaces. To use this method, you need to follow the instructions and procedures in the AFM, and apply the appropriate corrections and factors to your conditions. This method is the most complex and comprehensive, but also the most specific and accurate.

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Conclusion

The takeoff speed of an airplane is an important parameter that affects its safety and performance. It depends on many factors, both internal and external, that can vary for each flight. There are different methods to calculate the takeoff speed of an airplane, depending on its type and model.

Some of them are simple and easy to use, but not very accurate. Others are complex and comprehensive, but very precise. The best method to use is the one that is approved by the manufacturer and provided in the Aircraft Flight Manual.

Frequently Asked Questions

Q: How do I find the group number for my airplane model?

A: You can find the group number for your airplane model in the [FAA Advisory Circular 61-21A], which provides a list of common light airplanes and their corresponding group numbers.

Q: How do I find the Aircraft Flight Manual (AFM) for my airplane model?

A: You can find the Aircraft Flight Manual (AFM) for your airplane model in the [FAA Type Certificate Data Sheets], which provide the specifications and limitations of each certified airplane model. You can also contact the manufacturer or the owner of the airplane to obtain a copy of the AFM.

Q: What is the difference between indicated airspeed and true airspeed?

A: Indicated airspeed is the speed that is shown on the airspeed indicator in the cockpit, which measures the pressure difference between the static and dynamic air around the airplane. True airspeed is the actual speed of the airplane relative to the surrounding air, which depends on the density and temperature of the air. True airspeed is usually higher than indicated airspeed at higher altitudes and lower temperatures.

Q: What is the difference between takeoff speed and rotation speed?

A: Takeoff speed is the minimum speed that an airplane needs to generate enough lift to become airborne. Rotation speed is the speed at which the pilot pulls back on the control column to raise the nose of the airplane and initiate liftoff. Rotation speed is usually slightly lower than takeoff speed, and depends on the weight and balance of the airplane.

Q: What is V1 speed and why is it important?

A: V1 speed is the maximum speed at which a pilot can abort a takeoff and stop safely on the runway. It is also known as the decision speed or critical engine failure speed. It is important because it determines whether a pilot can continue or reject a takeoff in case of an emergency, such as an engine failure, a bird strike, or a tire blowout.

What is the difference between takeoff and landing speed?

The difference between takeoff and landing speed is not very large for most commercial airplanes, but it can vary depending on the type and model of the airplane, as well as the weight, altitude, temperature, wind, and runway conditions. Generally, the takeoff speed is slightly higher than the landing speed, because the airplane needs more lift to overcome its weight and drag during takeoff. However, the landing speed is also affected by the angle of descent and the braking system of the airplane.

According to one source, the average takeoff speed for a commercial jetliner is around 130-160 knots (150-200 mph or 240-320 km/h), while the average landing speed is around 150-165 knots (170-190 mph or 275-305 km/h). However, these are only rough estimates, and the actual speeds may vary for different airplane models and flight conditions. For example, a Boeing 737-800 has a typical takeoff speed of about 180 knots (207 mph or 333 km/h), while a Cessna 172 has a typical takeoff speed of about 55 knots (63 mph or 102 km/h).

To calculate the exact takeoff and landing speed for a specific airplane model, you need to use the data and charts provided by the manufacturer in the Aircraft Flight Manual (AFM). The AFM contains tables and graphs that show how different factors affect the takeoff and landing performance of the airplane, such as weight, altitude, temperature, wind speed and direction, runway slope and surface, wing flap setting, and engine thrust.

You need to follow the instructions and procedures in the AFM, and apply the appropriate corrections and factors to your conditions. This method is the most accurate and reliable, but also the most complex and comprehensive.

How does altitude affect takeoff and landing performance?

Altitude affects takeoff and landing performance in the following ways:

  • Increased takeoff distance: The higher the altitude of the airport, the less dense the air is, and therefore the less lift it provides. This means that planes need to go faster to take off at higher altitudes than at lower ones. As a rule of thumb, the takeoff distance is increased by one percent for every 100 feet of aerodrome pressure altitude above sea level1.
  • Reduced rate of climb: The higher the altitude of the airport, the less dense the air is, and therefore the less power and thrust the engines can produce. This means that planes have a lower rate of climb at higher altitudes than at lower ones. As a rule of thumb, the rate of climb is reduced by 10 percent for every 1,000 feet of density altitude above sea level2.
  • Increased landing roll distance: The higher the altitude of the airport, the less dense the air is, and therefore the less drag it creates. This means that planes have a higher true airspeed on approach and landing at higher altitudes than at lower ones, but the same indicated airspeed. As a rule of thumb, the landing roll distance is increased by one percent for every 400 feet of aerodrome pressure altitude above sea level.
  • Increased true airspeed on approach and landing: The higher the altitude of the airport, the less dense the air is, and therefore the less accurate the airspeed indicator is. This means that planes have a higher true airspeed on approach and landing at higher altitudes than at lower ones, but the same indicated airspeed. As a rule of thumb, the true airspeed is increased by two percent for every 1,000 feet of density altitude above sea level.

To calculate the exact takeoff and landing performance for a specific airplane model and condition, you need to use the data and charts provided by the manufacturer in the Aircraft Flight Manual (AFM). The AFM contains tables and graphs that show how different factors affect the takeoff and landing performance of the airplane, such as weight, altitude, temperature, wind speed and direction, runway slope and surface, wing flap setting, and engine thrust. You need to follow the instructions and procedures in the AFM, and apply the appropriate corrections and factors to your conditions.

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