Mastering the skies: The impact of g-forces on pilots and aircraft

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27-01-2024

    g-force, often called a type of force, measures how quickly earth's gravity accelerates an object or person

    The term is written in lowercase and italicized as g force.

    g-force works in a number of ways

g-force, often called a type of force, measures how quickly earth’s gravity accelerates an object or person. The term is written in lowercase and italicized as g force.

It’s crucial to remember that g-force is shown with a lowercase ‘g’ to set it apart from the Gravitational Constant, which is ‘G’. It’s also in italics to distinguish it from the symbol for gram, which is also ‘g‘.

The most recognized g forces are 0 g, found in places without gravity, like space; and 1 g, which is the force felt by everything on earth’s surface above sea level.

■ Acceleration is the change in speed, direction, or both. It describes how quickly an object speeds up, slows down, or changes its direction of movement.The unit of acceleration is metres per second squared (m/s²). 

  • A simple example: If a car speeds up from 0 to 60 metres per second in 10 seconds, its acceleration is 6 m/s².
  • So, the car’s acceleration is 6 metres per second squared, meaning its speed increases by 6 metres per second every second for 10 seconds.

How does g force work?

■ While seated in a moving car, we encounter g forces with any speed or direction change.

  • For instance, when the car speeds up (accelerates) or stops, we feel g forces along our body’s length (longitudinal g-force), either pushing us back or forward .
  • And when the car turns, g forces push us from side to side (lateral g force ).
  • The more sudden the car’s movement, the greater the g force we feel.

How do g forces affect us when flying in an airplane?

It may sound straightforward, but in order for an airplane to fly, an amount of upward g-force that matches or exceeds its own weight must be applied. 

In reality, whenever an airplane undergoes changes in speed, altitude, or direction along its axes, it will experience additional g-forces that can either partially counteract its weight or, conversely, amplify it.

Indeed, the ability to handle and manage g-forces is an integral part of a pilot’s training. Pilots undergo specialized training to develop the necessary skills to effectively handle and control the effects of g-forces during maneuvers and flight operations.

How to calculate g-force

It is a relatively simple task for a pilot to determine the level of g-forces they are being subjected to when initiating a turn.

To calculate the g-forces generated during a turn, a straightforward formula is used that relates the degrees of pitch of the aircraft, represented by 

1/cos(alpha) = g forces.

where alpha is the aircraft’s degrees of pitch.

  • The degree of pitch indicates the angle at which the front of the aircraft is tilted upwards or downwards relative to the horizon. It is used to calculate the g-forces generated during a turn.
  • In aviation, the term “horizon” refers to the imaginary line that separates the sky from the earth’s surface. It serves as a visual reference for pilots to determine their aircraft’s orientation and attitude relative to the ground.

By plugging in specific values into the formula, it becomes evident that a 45-degree turn corresponds to 1.41 g-forces, while a 60-degree turn yields 2 g-forces

Fortunately, pilots do not need to perform these calculations in real-time as most aircraft are equipped with g-force meters.

g-force and pilots 

Pilots experience significant impacts from g-forces. For instance, in a 60-degree turn, a pilot weighing 80kg would effectively double their weight to 160kg, making movements of the arms and legs more challenging. 

However, there is no need to be concerned as pilots undergo training to effectively cope with and adapt to these effects.

Under intense or strong g-forces, a condition often referred to as a blackout may occur, also known as g-loc, an acronym for g-force induced loss of consciousness.This is when blood is forced to the lower part of the body, leading to a temporary loss of sight. This effect is depicted in the movie “Top Gun: Maverick“.

While commercial flights experience minimal g-forces, military pilots regularly face them. 

To counteract this, they wear specialized suits that compress the lower body, making it less easy for blood to flow downwards.

Through proper training and methods, military and acrobatic pilots can endure forces up to 10 g. It’s quite astonishing, isn’t it?

Pilot Training to withstand g-forces

That funny feeling in your stomach when you’re in a fast elevator, on a roller coaster, or driving down a ramp? That’s caused by g-forces on your body.

Initially, the sensation might surprise you, but with repetition, your body adapts and the feeling lessens. Pilots experience something similar. Their training to handle g-forces is based on this principle. As they accumulate more flight hours, the impact of g-forces on them decreases.

In the military, there are high-speed rotating devices that enable pilots to experience and simulate the effects of g-forces.

Positive g-forces and negative g-forces

g-forces are classified into two types: positive g-forces and negative g-forces.

Positive g-forces occur during maneuvers  like sharp turns or steep ascents (climbs), resulting in blood accumulating in the lower regions of the body.

Conversely, negative g-forces arise when controls are pushed forward or during steep descents. Unlike positive g-forces, these cause blood to move towards the head.This can make you see red spots or lose vision, because your eyes get too much blood pressure. This is called redout, which stands for red vision due to negative g-force. 

In negative g-force you feel less than 1g of gravity, which makes you feel lighter than normal and would be pulling you out of your seat

Negative g-forces are the most challenging and uncomfortable to endure, as we are less accustomed to them in our daily lives.

Classification of Aircraft based on g-force tolerance

Just like individuals, different aircraft have varying capabilities to endure g-forces. 

To guarantee the safety of aircraft operations, it is crucial that they are constructed to withstand specific ranges of g-forces as excessive amounts can strain the structure and result in potential structural failures.

Aircraft design is essential in reducing the effects of g-forces during flight, with manufacturers carefully considering several factors to enhance safety and comfort for pilots and passengers. Maintaining the structural integrity of the aircraft is a major aspect that is given significant attention.

Manufacturers can enhance aircraft strength while reducing weight by utilizing materials with high strength-to-weight ratios, like carbon composites. This allows for the construction of lighter yet stronger aircraft capable of withstanding higher g-forces without compromising safety.

The position of the center of gravity is a crucial design consideration that can help mitigate the impact of G-forces during aircraft maneuvers. A well-balanced aircraft can minimize the effects of g-forces. Furthermore, the incorporation of advanced avionics systems and flight control technologies can provide pilots with assistance in effectively managing and mitigating g-forces.

There are multiple classifications or categories based on their tolerance to these forces.

■ Normal

  • Maximum positive: 3.8 g
  • Maximum negative: -1.52 g

■ Utility

  • Maximum positive: 4.4 g
  • Maximum negative: -1.76 g

■ Acrobatic

  • Maximum positive: 6 g
  • Maximum negative: -3 g

Commercial aircraft

  • Maximum positive: 2.5 g (2 g if flaps extended)
  • Maximum negative: -1 g

Pilots must possess knowledge about their aircraft’s limitations to prevent excessive stress. Moreover, increased levels of g-forces experienced by an aircraft necessitate more meticulous and precise maintenance procedures.

 (The author Girish Linganna, is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach out to him at: girishlinganna@gmail.com)

Mastering the skies: The impact of g-forces on pilots and aircraft

https://newsfirstprime.com/wp-content/uploads/2024/01/WhatsApp-Image-2024-01-26-at-5.25.30-PM.jpeg

    g-force, often called a type of force, measures how quickly earth's gravity accelerates an object or person

    The term is written in lowercase and italicized as g force.

    g-force works in a number of ways

g-force, often called a type of force, measures how quickly earth’s gravity accelerates an object or person. The term is written in lowercase and italicized as g force.

It’s crucial to remember that g-force is shown with a lowercase ‘g’ to set it apart from the Gravitational Constant, which is ‘G’. It’s also in italics to distinguish it from the symbol for gram, which is also ‘g‘.

The most recognized g forces are 0 g, found in places without gravity, like space; and 1 g, which is the force felt by everything on earth’s surface above sea level.

■ Acceleration is the change in speed, direction, or both. It describes how quickly an object speeds up, slows down, or changes its direction of movement.The unit of acceleration is metres per second squared (m/s²). 

  • A simple example: If a car speeds up from 0 to 60 metres per second in 10 seconds, its acceleration is 6 m/s².
  • So, the car’s acceleration is 6 metres per second squared, meaning its speed increases by 6 metres per second every second for 10 seconds.

How does g force work?

■ While seated in a moving car, we encounter g forces with any speed or direction change.

  • For instance, when the car speeds up (accelerates) or stops, we feel g forces along our body’s length (longitudinal g-force), either pushing us back or forward .
  • And when the car turns, g forces push us from side to side (lateral g force ).
  • The more sudden the car’s movement, the greater the g force we feel.

How do g forces affect us when flying in an airplane?

It may sound straightforward, but in order for an airplane to fly, an amount of upward g-force that matches or exceeds its own weight must be applied. 

In reality, whenever an airplane undergoes changes in speed, altitude, or direction along its axes, it will experience additional g-forces that can either partially counteract its weight or, conversely, amplify it.

Indeed, the ability to handle and manage g-forces is an integral part of a pilot’s training. Pilots undergo specialized training to develop the necessary skills to effectively handle and control the effects of g-forces during maneuvers and flight operations.

How to calculate g-force

It is a relatively simple task for a pilot to determine the level of g-forces they are being subjected to when initiating a turn.

To calculate the g-forces generated during a turn, a straightforward formula is used that relates the degrees of pitch of the aircraft, represented by 

1/cos(alpha) = g forces.

where alpha is the aircraft’s degrees of pitch.

  • The degree of pitch indicates the angle at which the front of the aircraft is tilted upwards or downwards relative to the horizon. It is used to calculate the g-forces generated during a turn.
  • In aviation, the term “horizon” refers to the imaginary line that separates the sky from the earth’s surface. It serves as a visual reference for pilots to determine their aircraft’s orientation and attitude relative to the ground.

By plugging in specific values into the formula, it becomes evident that a 45-degree turn corresponds to 1.41 g-forces, while a 60-degree turn yields 2 g-forces

Fortunately, pilots do not need to perform these calculations in real-time as most aircraft are equipped with g-force meters.

g-force and pilots 

Pilots experience significant impacts from g-forces. For instance, in a 60-degree turn, a pilot weighing 80kg would effectively double their weight to 160kg, making movements of the arms and legs more challenging. 

However, there is no need to be concerned as pilots undergo training to effectively cope with and adapt to these effects.

Under intense or strong g-forces, a condition often referred to as a blackout may occur, also known as g-loc, an acronym for g-force induced loss of consciousness.This is when blood is forced to the lower part of the body, leading to a temporary loss of sight. This effect is depicted in the movie “Top Gun: Maverick“.

While commercial flights experience minimal g-forces, military pilots regularly face them. 

To counteract this, they wear specialized suits that compress the lower body, making it less easy for blood to flow downwards.

Through proper training and methods, military and acrobatic pilots can endure forces up to 10 g. It’s quite astonishing, isn’t it?

Pilot Training to withstand g-forces

That funny feeling in your stomach when you’re in a fast elevator, on a roller coaster, or driving down a ramp? That’s caused by g-forces on your body.

Initially, the sensation might surprise you, but with repetition, your body adapts and the feeling lessens. Pilots experience something similar. Their training to handle g-forces is based on this principle. As they accumulate more flight hours, the impact of g-forces on them decreases.

In the military, there are high-speed rotating devices that enable pilots to experience and simulate the effects of g-forces.

Positive g-forces and negative g-forces

g-forces are classified into two types: positive g-forces and negative g-forces.

Positive g-forces occur during maneuvers  like sharp turns or steep ascents (climbs), resulting in blood accumulating in the lower regions of the body.

Conversely, negative g-forces arise when controls are pushed forward or during steep descents. Unlike positive g-forces, these cause blood to move towards the head.This can make you see red spots or lose vision, because your eyes get too much blood pressure. This is called redout, which stands for red vision due to negative g-force. 

In negative g-force you feel less than 1g of gravity, which makes you feel lighter than normal and would be pulling you out of your seat

Negative g-forces are the most challenging and uncomfortable to endure, as we are less accustomed to them in our daily lives.

Classification of Aircraft based on g-force tolerance

Just like individuals, different aircraft have varying capabilities to endure g-forces. 

To guarantee the safety of aircraft operations, it is crucial that they are constructed to withstand specific ranges of g-forces as excessive amounts can strain the structure and result in potential structural failures.

Aircraft design is essential in reducing the effects of g-forces during flight, with manufacturers carefully considering several factors to enhance safety and comfort for pilots and passengers. Maintaining the structural integrity of the aircraft is a major aspect that is given significant attention.

Manufacturers can enhance aircraft strength while reducing weight by utilizing materials with high strength-to-weight ratios, like carbon composites. This allows for the construction of lighter yet stronger aircraft capable of withstanding higher g-forces without compromising safety.

The position of the center of gravity is a crucial design consideration that can help mitigate the impact of G-forces during aircraft maneuvers. A well-balanced aircraft can minimize the effects of g-forces. Furthermore, the incorporation of advanced avionics systems and flight control technologies can provide pilots with assistance in effectively managing and mitigating g-forces.

There are multiple classifications or categories based on their tolerance to these forces.

■ Normal

  • Maximum positive: 3.8 g
  • Maximum negative: -1.52 g

■ Utility

  • Maximum positive: 4.4 g
  • Maximum negative: -1.76 g

■ Acrobatic

  • Maximum positive: 6 g
  • Maximum negative: -3 g

Commercial aircraft

  • Maximum positive: 2.5 g (2 g if flaps extended)
  • Maximum negative: -1 g

Pilots must possess knowledge about their aircraft’s limitations to prevent excessive stress. Moreover, increased levels of g-forces experienced by an aircraft necessitate more meticulous and precise maintenance procedures.

 (The author Girish Linganna, is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach out to him at: girishlinganna@gmail.com)

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