How Does an Ejector Seat Work?

STEP 1

ACTIVATE THE TRIGGER

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n an aircraft the ecjector seat (or ejection seat) is used during emergencies, where the pilot is required to exit the vehicle whislt it is still in flight.

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Gear stick triggers seem to be reserved solely for spy films.

Therefore this process is activated using a handle (either located between the pilots legs or on the side of the chair), in some cases a face covering is pulled down in order to activate the process instead.

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This is the case with Agent NAME RETRACTED, shown in the right hand diagram.

Ejection seats are usually grey to differentiate them from their black counterparts.

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STEP 2

SENSORS

Sensors in the chair determine how the seat should blow.

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It does this first by measuring speed using two pitot tubes (one for backup) to measure aerodynamic pressure. While a port behind the seat measures ambient pressure.

Then central processing takes this into account and calculates one of three possible modes to activate whilst firing the chair. This prevents the pilot from making contact with the plane on exit, and helps counteract detremental G-forces.

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STEP 3

HATCH RELEASE As soon as the ejection seat has been triggered, a hatch in the roof blows off.

An electrical pulse signals thrusters to unlock the hatch and throw up into the air.

All of this occurs before the chair is fired so as to avoid injury.

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This process, like the chair firing itself, is dictated by the central processing system.

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STEP 4

FIRING THE CHAIR The chair is violently thrust from the plane at speeds in excess of 810mph. This often results in compression fractures to the pilot’s spine.

The fore and pressure required to fire the chair is 1930 NEWTONS + 8870 PASCALS

Chairs used to be fired using a hydrolic pistons, but now commonly use multiple rocket units feeding into a single nozzle under the chair. They are a series of small white tubes filled with rocket fuel and burn for about 0.2 seconds.

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STEP 5

STABALISING SYSTEMS Ejection seats used to use weights to stabalise themselves (shown in the diagram on the right). But this was considered too risky as the pilot would have to be lifted from the chair when the parachute was deployed, as it was too heavy to take with it. Which may have cause further damage to compression fractures, as well as

A tiny parachute releases out of the top, prior to the main parachute releasing. This stabalises the chair and prevents it from spinning out of control.

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STEP 6

PARACHUTE DEPLOYeD The parachute releases a few seconds after departure using an automatic opening device. It is attached to the chair by a lanyard, and counteracts the G-force with its vast surface area, slowing down the pilot; preparing them for landing.

To determine the speed of the seat at any point in time as it slows down one would just have to apply the Newton equasion to it, taking into account the overall mass (pilot + chair).

Speed = Acceleration x Time + Initial Speed

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STEP 7

LANDING

A survival pack (called a bucket) hangs from the base of the chair, it is filled with food, medicine and other supplies for when the pilot lands, and can assist with judging the landing as it goes slack as it hits the ground.

CLASSIFIED Once the pilot has landed they have to unbuckle themselves, and release their leg restraints (which are activated to prevent themselves from being injured by the G-force and falling debris).

In the 1940s only 50% of ecjections were successful, today that number has risen to 90%

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UP TO WHEN THE PARACHUTE IS DEPLOYED

THE WHOLE PROCESS TAKEs 1/10th OF A SECOND

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Propery of MI6 Written by Alex Ruse & Jim Williamson

May contain CLASSIFIED information