It was definitely not the time to be having second thoughts.

For the driver attempting the world's largest loop-the-loop, a moment's hesitation could have been fatal.

If stuntman Steve Truglia had been too timid in his acceleration, his yellow Toyota would have reached the top of the track and dropped like a stone.

Loopy: Stuntman Steve Truglia successfully completes the first British attempt at the loop-the-loop by car

But if he had driven in too fast, the G-force generated could have knocked him unconscious.

Either way, his route down from the high point of the 40ft loop would have been, shall we say, less than graceful.

But as this extraordinary picture shows, Mr Truglia's timing and speed were perfect.

The breathtaking stunt - planned with the help of a Cambridge physicist - was filmed at a Suffolk airbase for Channel Five's car show Fifth Gear.

It will be shown in a special episode next Saturday at 11.30am.

I'm going in: Mr Truglia approaches the loop, driving at 37mph

John Nolan, of North One Television, which produces Fifth Gear, admitted that Mr Truglia was dicing with death by taking on the challenge - known to stuntmen as the 'death loop'.

'This is definitely the highest loop-the-loop in a real car ever,' he said. 'If he had blacked out he might not be here now.'

Success: Mr Truglia after his achievement

To stop this happening, Mr Truglia took part in endurance training in an aircraft to get his body used to the stresses of the G-forces involved.

Fighter pilots are trained to tense the muscles in their legs, arms and abdomens to restrict the flow of blood away from their brains, which could cause a blackout.

Mr Truglia also had to overcome his natural urge to bail out.

But after successfully completing the stunt, he is now ready for his next adventure - skydiving from space.

Life or death precision

Steve Truglia successfully completed the stunt by precise control of centripetal  - often incorrectly known as centrifugal  - force.

The Toyota had to be travelling fast enough that the centripetal force generated by its circular motion 'offset' the downward pull of gravity. This required the stuntman to enter the loop at exactly 37mph, immediately change out of gear and slow to 16mph as the vehicle swung round the top.

He was helped by the fact that the front and back of the car had been carved off to stop it scraping the track and slowing down.

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