The Negative G Reflex

Negative G Reflex

 The Wright Brothers taught themselves to fly. Many others had tried and failed, some killing themselves. The Wrights began with kites and progressed to gliders. Only when they had mastered gliding did they fit an engine to make the first successful, fully controlled aeroplane flights.

Long before the outbreak of World War 1, methods of training pilots in two seat aeroplanes with dual controls had been developed.

In retrospect it seems extraordinary that when gliding began as a sport in 1920, there was a reversion to learning in single seaters. The pupil pilot got into, or rather onto, the primary training glider and was strapped to the seat. The instructor explained the exercise, stood back, and the glider was launched.

 

A primary glider similar to those used for solo training.

This was not quite so ridiculous and dangerous as it sounds. The first trials were brief slides along the ground, with enough speed through the air to make the ailerons and rudder effective. After a few such slides the beginner, having learned to keep the wings level and go straight, would be launched a little faster and might get a metre or two off the ground, to glide down to land within a few seconds. By using the control stick, moving it back or forward, the nose-up or nose-down attitude could be controlled. You couldn’t hurt yourself this way, it was said.

Try falling onto your bottom from a couple of metres or three.

A nervous pupil could push the stick forward too hard, pitch nose down and hit the ground hard. The primary gliders had no springing in the keel. The seat, a simple plank of wood, was glued rigidly to the solid wooden keel. In a bad landing the shock was transmitted instantly to the pilots’ spine. Compressed vertebrae were not uncommon.

I once saw a young woman at this stage of her flying, clutch the stick back hard, pitching the glider steeply up to about three metres, causing the wing to stall. The whole thing rolled over sideways into a bundle of matchwood. She, fortunately, escaped uninjured but we never saw her at the gliding club again.

I witnessed this incident in 1947 when I was seventeen and was myself a trainee. The solo method was still in use at almost all gliding clubs in the world at this time. (It was still being used in 1950, thirty years after it had been introduced.)

After a few low hops, the strength of the launch was increased and the pupil progressed to slightly higher hops, and, if all seemed to be going well, higher. Each time, the instructor would explain, then stand back and watch with interest as the glider was launched. The idea was to climb with the control stick slightly back to about 100 or 150 feet, then ease the stick forward to return to level flight, release the launching cable and glide down gently to land. There were no instruments so the pupil had to guess the height and judge the speed by the pressure and sound of the airflow.

A pupil who managed this would move on to learn how to make turns, using the stick rudder and ailerons in coordination to bank the wing over to one side, so causing a turn, then level the wings again to go straight, then bank and turn the other way, straighten up and land straight ahead.

I reached this stage in August 1947. I was very nervous and not wise enough at that age, to ask for more low and gentle hops before going on to the higher ones with the complications of turning.

I was pulled up by the winch to a height greater than I had ever been before, levelled out and attempted to make the turns, which were certainly not well done. I landed safely.

‘That was very clumsy, Martin,’ said Bernard, the instructor. ‘This time, go higher to give yourself more time and then ease more gently into the turns.’

Off I went, climbing steeply until I was sure I was high enough. Too high! Higher than I had ever been before! To stop going up I hastily pulled the knob to release the cable. I should have used the stick to get into a level attitude first. Dropping the line while climbing caused the nose of the glider to pitch up. I remember pushing the stick forward to level out.

The next thing I remember was hearing a rush of air screaming past. I opened my eyes. The ground was immediately in front of me, coming up very rapidly. I pulled the stick hard back., which saved my life.  Then I was lying on the ground looking up at shattered bits of glider wing above me. My left leg, I saw, was in a very strange and distorted position with the foot still attached by the stirrup to the rudder pedal. There was a pain in my back.

‘I’ve broken my leg!’ I said.

‘By God, you have,’ said the voice of Tony Benson, the first person to reach me.

‘Lie still, Martin, don’t try to move.’ He was, fortunately for me, a fourth year medical student and knew what to do. I think he saved the leg from developing into a very dangerous compound fracture as the muscles contracted after the shock. I diagnosed the back injury myself. I had read of this kind of injury. I had crushed three vertebrae.

I did not know why I crashed and nor did anyone else, but I was far from the first to have this kind of accident. At another club on the South Downs of England, on that same weekend, another young fellow was killed outright in exactly similar circumstances. I definitely had a moment of unconsciousness as I pushed the stick forward. If I had not opened my eyes when  I did I would have hit the ground vertically and that would have been the end of me.

Many years later an explanation of these accidents emerged. The cause became known as the negative G reflex. Changing suddenly from a steep climb to level flight lifts the pilot’s bottom off the seat. This happens on some kinds of fairground ride. For a moment, one is weightless. It is a falling sensation. Very young children, at the toddling stage, sometimes have this feeling. When they do, they close their eyes and push their hands forward to save themselves in the fall. It is a reflex action.

The trouble is, in any kind of aircraft, one hand at least is holding the control stick. Pushing that forward makes the sensation worse, the weightlessness becomes a strong negative force, one is thrown hard against the shoulder straps. The reflex becomes stronger. The aircraft pitches violently nose down and into the ground. That is what happened to me.

You can guess what my father said.

It took me a while to get back into the air again, and I thereafter learned to fly the sensible way in two seaters with instructors to correct my wildest movements.

About fifty years later I had some bothersome sensations in my left hand. It was discovered that I had more than crushed lumbar vertebra. I had two crushed bones in my neck as well. They did not examine these in 1947. Fortunately the bones had fused together but apparently my neck movement has never been quite normal! I didn’t know. Nor did I know until last year, when I had some minor knee surgery, that my left leg is half an inch shorter than the right.

I don’t recommend learning to fly without an instructor sitting with you.

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