You might wonder how a human cannonball can survive the act unscathed by gunpowder burns. The fact is, there's actually no gunpowder used in these big cannons (and, historically, never has been), which can be more than 30 feet (9 meters) long [source: American Profile]. Instead, modern cannons employ the power of compressed air or springy bungee cords. Performers keep the exact mechanics a secret to add to their mystique and to prevent others from copying their machines.
There's nothing cryptic, though, about the basic life-or-death mechanics involved in becoming a fleshy projectile. Inside the barrel of the cannon is an empty cylinder, into which the performer climbs. This cylinder acts as a sled of sorts.
When it fires, the cannon pushes the sled forward at a force of 3,000 to 6,000 pounds per square inch (psi) of pressure [source: New York Times]. The sled stops once it reaches the muzzle of the cannon, but the person inside just keeps right on going, often sending its warm-blooded bomb to a horizontal distance of nearly 200 feet (61 meters), or 200 feet high, at speeds of up to 60 to 70 miles per hour (96.5 to 112.6 kilometers per hour).
When workers or performers set up the cannon, they have to take into account a slew of factors, including wind speed, body weight, potential obstacles (such as tree branches or guy lines, the anchoring lines that help hold the net in place), distance, humidity and even temperature. They also have to take great care in their calculations of barrel angle.
Body weight, especially, plays a major role in the act. Smaller, lighter people are easier to accelerate (and decelerate), which means that very large and heavy people do not generally pursue cannonballing as a career path.
Circus performers are keen to point out that it's not really that hard to launch a human being into the air, even to very great heights or long distances. It's the landing that causes problems. To that end, most acts use a large net or even airbags to absorb the forward energy of the "cannonball."
But even very large nets, which measure about 50 by 25 feet (15 by 7.6 meters), make for frighteningly small targets when your life depends on their proper placement and solid construction. That's why workers and performers do test runs before every performance by stuffing a weighted dummy into the barrel and launching it to see where it lands.
If their calculations are correct, the dummy makes a safe landing in the net. If not, they make careful adjustments until they've ensured that both the cannon and the net are working just right. On an off day, when the mechanics of the cannon just don't seem to be working quite right, cautious performers have been known to cancel their acts until every potential problem has been fixed.
In spite of the careful calculations, human cannonballing is still a risky endeavor. So, why do people still do it -- and why do their families let them? Surprisingly, this performance is often a family affair that spans generations. Keep reading to see how some families have not only survived a multitude of salvos but also parlayed their resulting fame into lasting careers.