Tuesday, September 8, 2009

Up, up and Away!

Most of the jet aircraft at the Cold War Air Museum were equipped with ejection seats when they were in military service.
One of the first actions on arrival is to check and insure that these seats have been disarmed or disabled. While this makes the aircraft safe to work on and to move around in, it begs the question- “Hot or Cold”?

Should the seats be “hot” during flight or “cold”? Because the use of the ejection seat has a training requirement prior to useage, the consensus has been to leave the ejection seats “cold” and rely on the robust nature of the airframe and the skills of the pilot should an emergency occurr and require an emergency landing. After all, no one is shooting at us over Lancaster.

In fact, the general consensus is that barring an on board fire, or the total loss of control function, the occupants are better off “riding it down” in the event of an emergency as the aircraft we fly are exteremely durable and robust. But enough of this, lets talk about where ejection seats came from and how they were developed.

A bungee-assisted escape from an aircraft took place in 1910. In 1916 Everard Calthrop, an early inventor of parachutes, patented an ejector seat using compressed air.
The modern pattern for a plane was invented by Romanian inventor Anastase Dragomir and its design was successfully tested on August 25, 1929 at the Paris-Orly Airport near Paris and in October 1929 at B─âneasa, near Bucharest.

The first ejection seats were developed independently during World War II by Heinkel and SAAB. Early models were powered by compressed air and the first aircraft to be fitted with such a system was the Heinkel He 280 prototype jet fighter in 1940.

After World War II, the need for such systems became pressing, as aircraft speeds were getting ever higher, and it was not long before the sound barrier was broken. Manual escape at such speeds would be impossible. The United States Army Air Forces experimented with downward-ejecting systems operated by a spring, but it was the work of Sir James Martin and the British company Martin-Baker that was to prove crucial.
Early seats used a solid propellant charge to eject the pilot and seat by igniting the charge inside a telescoping tube attached to the seat. Effectively, the seat was fired from the aircraft like a bullet from a gun. As jet speeds increased still further, this method proved inadequate to get the pilot sufficiently clear of the airframe and increasing the amount of propellant risked damage to the occupant's spine, so experiments with rocket propulsion began. The F-102 Delta Dagger was the first aircraft to be fitted with a rocket-propelled seat, in 1958. Martin-Baker developed a similar design, using multiple rocket units feeding a single nozzle. This had the advantage of being able to eject the pilot to a safe height even if the aircraft was on or very near the ground.

1 comment:

  1. I would have to disagree with your consensus that ejection seats should be left inactive in your tactical display aircraft. If you are planning actively flying such aircraft, you will come across many senarios within the flight envelope of the MiG-21/MiG-23 aircraft where "riding it out" is not an attractive option! The KM-1M seat might be known as not being kind to one's back but it's a better alternative to finding oneself with an inflight fire situation and sitting on a "cold" seat.