Everything You Want To Know About Ejection Seat

In today’s era of modern warfare, the safety of pilot is assuming even greater importance. Probably because training a pilot is very high and most importantly we cannot afford to lose a dedicated man.  In today’s era when air force dominates the war scene, the chances of an aeroplane getting damaged are still greater. Hence it is quite important to make a way for safe escape of the pilot. The solution for ensuring this is nothing but the ejection seat. To make my point clear an ejection seat is nothing but the chair of pilot which can be detached from the plane whenever the need be.



However the scheme is not as simple as it seems to be. The system has evolved from a basic idea into a highly complicated system which in turn includes many more subsystems. An ordinary seat is mounted on rails which guide it on its initial trajectory. Mostly the seat consists of a padded bucket, back and a headrest. The ejection system can be activated by pulling a fire handle. The principle behind it is rocket propulsion. The system also has an inbuilt parachute.

The seat ejection system in a T-37 type of seat has a back-type parachute and is equipped with what is called as an inertial reel shoulder harness, a lap belt which operates automatically and a mechanism to separate to remove the seat called as a ‘seat separator’. The whole system is also provided with quick disconnecting fittings and an Oxygen hose. The whole arrangement can be manually adjusted if the need be and the seat is equipped with a canopy piercer which breaks the canopy. This is located on top of the seat. The whole assembly is activated in just 0.33 sec.

Now there are certain predefined stages of seat ejection. Namely:

1) Pre-Ejection
2) Primary acceleration
3) The parachute descent stage.

The pre-ejection stage is a very critical stage and exists for a very short time. The time required by the system until ejection from the need to exit an aeroplane is called pre-ejection time. The next stage is the primary acceleration. In this stage numerous factors play a key role. The factors are the temperature, weight of the pilot, the velocity of aeroplane, velocity and direction of wind etc. This is such a critical stage that most of the injuries happen during this period. G forces of magnitude of 12 to 20 Gs are common. However if they increase beyond 25 Gs then there is a remarkable increase in the probability of spinal injury.

Then there is another type of force called Q-force. These forces are produced either by wind-blast. These things matter so because the pilot is under a constant threat of retinal or conjunctive hemorrhages. However as compared to losing a precious life these are nothing! A pilot can always recover from these injuries. The important task in our hand is to minimize the possibility of such injuries.

The last stage is parachute landing stage. The high-speed escape close to ground is the most difficult ejection sequence. As a thumb rule, the initial thrust produced must be adequate to clear rapidly moving tail section. The time delays will always be necessary to minimize the loss of altitude because the wind blast will be high.

Even after such modern equipments, the system is still in a developing stage mostly using rocket propulsion but in future we may expect a controllable propulsion system. In today’s era a research on high altitude ejection at a high speed is still going on. It always so happens that the thing at which we laugh at present becomes a necessity in the future!