How does an ejection seat work? In the simplest sense, they remove the canopy to the plane and then launch the pilot on their seat into the sky before a parachute deploys.
Ejection seats are a lot more advanced than they were when they were first invented. The first ejection seats were first used during the Second World War. During the First World War, planes were in their infancy and they didn’t have a canopy. If a plane was shot down, the only option for the pilot was to bail out over the side with their own parachute. This wasn’t easy and a lot of pilots went down with their planes. In the 1920s, planes became faster and they started to have canopies. The first basic ejection seat was developed in 1929. They were developed during World War 2, but most WW2 planes didn’t have any ejection system. Pilots had to manually open the canopy and then jump out, which was all but impossible. They had to roll over the side of the plane, because kicking off would put them in line with the tail, then count to ten to clear the plane and pull their ripcord. Not many pilots survived being shot down.
Once the jet was invented by the end of WW2, there was no way a pilot could manually eject. The planes flew too fast for them to be able to jump out and companies started developing ejection systems. The early systems basically just shot the pilot out of the plane, but modern systems are very sophisticated.
It is very difficult for a pilot to make the decision to eject because the planes they are flying are usually multi-million-dollar planes. They also run the risk of severe injury if they eject at high speed. However, no plane is worth more than a life and people can recover from injuries. Pilots sometimes have time to make the decision to eject, sometimes they have to react very quickly.
Once the decision to eject has been made, the pilot pulls the lever that is usually on the chair between the legs. If there is a rear copilot, in modern aircraft, that seat automatically starts the ejection sequence as well. To the human eye, once the lever is pulled it appears as though ejection is instant, but the computers on the chairs go through several steps in milliseconds. The first step is to launch the canopy. We have all seen Top Gun and know what happens if the canopy doesn’t launch. The canopy is designed to blow up so that it gets caught in the air racing past the plane, which will have enough force to rip it off. Some canopies are designed to shatter.
Once the canopy is gone, the chair makes some rapid calculations. A tube behind the pilot measures aerodynamic pressure to work out the speed of the airplane. The chair is independent of the controls of the airplane and makes its own calculations in case the plane controls are not functioning. The chair also samples the ambient air pressure to work out the altitude.
The chair is launched up a rail and out of the plane by a catapult. As soon as the chair has left the plane a rocket fires to carry the chair up and away. The rocket is there to get the pilot away from the plane, but it is also there to stabilize the chair. If the chair just ejected into the passing air, it would be tossed and rolled all over the place. The rocket keeps the chair up and is why the chair needed to know the air speed. If there is a copilot, the copilot’s chair will eject first so that the copilot isn’t burned by the rocket on the pilot’s chair.
When the rocket has finished firing, either the main parachute will open, or a drogue parachute will open, depending on the height. This is why the chair needed to know the altitude. If the pilot is low, the parachute will open straight away. If the pilot is high, they need to get down to breathable air quickly, so a drogue will open to stabilize the chair, but to still allow freefall. The chair does have an 8-minute backup oxygen supply if it is needed.
When the parachute opens, it pulls out some pins so that the chair falls away from the pilot. However, it is still connected to the pilot by a tether. It needs to swing out of the way so that the pilot can make a safe landing, but it still needs to be connected because it contains a lot of safety equipment that the pilot will need when they land. One thing it has is a water activated survival raft in case the pilot lands in the water.
90% of pilots who eject survive these days, compared to less than 50% when ejection seats were first invented. The main problem is that planes fly even faster these days. The fastest ever recorded ejection was at Mach 1.3. The pilot was hit by the wind like a sledgehammer and he broke his arm, his leg in five places, dislocated both his knees, and a host of other injuries, but he survived. Some people are working on a plane where the whole cockpit can eject, but I don’t know how practical that is.
Helicopters can have ejection seats as well. The ejection seat works in the same way as a plane, with one difference. When the explosives blow the canopy off, they also sever all of the rotor blades. This makes it safe for the pilot to eject upwards. And this is what I learned today.
Photo by Hilmi Işılak: https://www.pexels.com/photo/gray-fighter-plane-on-airport-4311318/
Sources
https://www.smithsonianmag.com/air-space-magazine/how-things-work-ejection-seats-29088450/
https://science.howstuffworks.com/transport/flight/modern/ejection-seat.htm
https://en.wikipedia.org/wiki/Ejection_seat
https://www.wearethemighty.com/mighty-history/wwii-pilots-bail-from-planes/
https://www.popularmechanics.com/military/aviation/a26193/how-pilots-eject-from-fighter-jet/