It is fear, primarily, that draws crowds to watch daredevils risk life and limb – the chest-tightening sense that a death-defying act could go wrong. It was a thrill that quickly evaporated in a horrible instant on Sunday afternoon, when a 23-year-old human cannonball died in front of hundreds of families.
The death of Matt Cranch – whose safety net failed, causing him to sustain horrific injuries in an accident that some disbelieving eyewitnesses thought was part of the act – has shocked a tiny community of men and thrown a spotlight on a world tied up in decades of tradition and secrecy.
One thing that separated Mr Cranch, who until two weeks ago was working as a barman in Newquay before leaving in a flurry of excitement to pursue his new adventure, was his route into what is a highly nepotistic profession. Chilean Rodrigo Perez, who is one the leading human cannonballs based in Britain, followed his uncle into the game. American Dave Smith Jnr recently took the world record for longest human cannonball "flight" – 185ft – from his father Dave Smith Snr, who at aged 67 hasn't ruled out getting the record back.
Raw nerve is far from the only skill required. "You have to be very strong in mind," says Mr Perez, 27, who is taking time off to build his new cannon – the parts of which he is sourcing from all over the world. "You have to have acrobatic skills. You have to understand physics, mathematics and engineering. And the very important one: you can't be scared of anything. That is the rule."
These stuntmen are also united by a code of silence about the mechanics of their art. "It's a secret," Mr Perez says. "It's magic." But cursory research reveals that early cannons were powered by coiled springs; today compressed air is used to fire men at speeds of up to 70mph. Gunpowder is only used to create the bang designed to get hearts racing.
Invented by the Canadian William Leonard Hunt, aka "The Great Farini", the first human cannonball was a 14-year-old girl, fired outside London's Royal Aquarium in 1877. The girl later toured with the renowned PT Barnum circus and left in her wake a peculiar art. No stuntman will even speculate on the number of people who can call themselves cannonballs. None can escape the risks.
"You've got to make sure you fly straight and true," says Mr Smith Jnr, 38, who has worked as a human cannonball for 13 years. "It's about positioning and focus. You've got a split second under very intense pressure. You've got to be ready for that split second. The first movement when you come out is very important. That's what sets you straight for the rest of the flight. You have to learn how to fly."
It's the thrill of flight that draws these men to their cannons. "I have a tremendous life," Mr Smith Jnr says. "And at the end of my day's work, everybody claps. It's a great feeling."
That is, until the unthinkable happens. A few years ago, during a live show, Mr Perez's safety net broke as he landed in it. He went straight through into the crowd below. "I can't remember anything about it," he says. "Apparently two ambulances arrived and one of them took me to hospital. I'm very lucky to be alive."
The net can often be the weakest link in a stunt that relies on guts as much as sharp shooting. "The net is about 50ft wide by about 20ft, but you have to hit the right part of it – about two-thirds of the way forward," Mr Smith Jr says. "You bounce quite a way back, and you have to remain inside. If you're off, you cannot hit a steel beam in a ceiling and walk away. You cannot miss your net and walk away. You cannot hit a stadium scoreboard and walk away."
Two weeks after his near-death experience, Mr Perez was back in the cannon. "I thought at the time: 'am I right to carry on?' But it's what I love to do. It's my passion," he says.
Now Mr Perez has one extra part to his build-up: "When I get into the cannon, I pray. One very short but very good prayer. The countdown has started, there isn't time for a long one."
Mr Perez and his wife don't have children yet, but if they eventually do he hopes they will follow him down the barrel. Would this not give his wife some concern? "No, my wife loves it," he says. "She pushes the fire button."
Mr Smith Jnr, who says he was saddened to hear of Mr Cranch's death, says he will not quit his peculiar pastime. "My son Maverick, he's four, he wants to be a cannonball, too and his twin sister, she wants to fire him out," he says.
Meanwhile, tributes came in yesterday for Mr Cranch, including one from his friend James White: "I know you went doing something that you absolutely loved, with your trademark smile on your face."