Steve Wolf might be the world’s first person to hold the title of “Stunt Scientist.” He’s like a magician who reveals how he pulls off illusions, but he’s not hiding tricks, just good science and smart use of numbers! Steve spoke with us about the explosive math behind movie stunts.
BTM: How did you decide you wanted to be a Stunt Scientist?
Steve: I probably knew from the time I was 5 or 6. I liked climbing, fire, jumping my bike, building go-carts, crashing toy cars and blowing them up, all while being careful not to get hurt. Stunt work may look dangerous, but it’s actually about safely using science to create the illusion of danger.
BTM: Could you give me an example of how you use math in creating a special effect?
Steve: It depends on the effect, but let’s say we want to create a snow scene for a movie. First we would find out how much area needs to be covered in snow, and how deep the snow should be. From those measurements we can find the volume of snow needed – if we’re laying down 2 feet of snow over a 10 by 10 foot area, then we need 200 cubic feet of snow. And we know that 30 pounds of ice turns into 1 cubic foot of snow when we put it into our snow maker, so we could figure out that we need 6000 pounds of ice to cover the space once. If the snow melts away four times in a day, we’ll need 24,000 pounds of ice to get through the day. And since an ice truck can hold 40,000 pounds of ice, we’ll only need parking for one truck.
BTM: What about making smoke for movies, how do you use math for that?
Steve: Creating a smoke effect has similar math to snow – we calculate the volume of the room to know how much smoke liquid we’ll need. Our smoke machines work by adding heat to liquids to turn the liquids into gas. And gasses take up much more space than the liquids they are made from. Smoke “juice” expands 1.3 billion times in volume when it turns into smoke. If you do the math, you’ll find that one gallon of smoke fluid makes a cloud of smoke 556 feet tall, wide and deep. That’s enough smoke to fill the pyramid of Giza twice!
We do many calculations for every stunt we do. Time and distance measurements are particularly important to safely set up a stunt or effect. For example, if we do a scene in which someone jumps from a helicopter onto a roof, we need to calculate how long the stunt person will be in the air, and how hard will they will hit the surface (we multiply speed times their weight to know their landing impact). That’s important so that we can make sure our airbags will be large and strong enough to absorb their force and cushion their fall.
BTM: How else do numbers help you stay safe?
Steve: Numbers help us quantify the action we’re creating. When we’re setting up a fireworks show, spectators must be at least 70 feet away from a firework that is 1 inch in diameter, and another 70 feet for each additional inch of diameter. That also helps us know how much caution tape we need to bring – we just calculate the circumference of a circle with a radius of 70 or 140 feet. If we’re making someone fly around on a system of pulleys and ropes, then we need to know how much weight the ropes and harnesses can support, and how we can distribute that weight across a number of pulleys. If there’s a scene where someone runs through fire, we need to know the temperature of the gas we’re burning and the amount of heat that the stunt person’s fireproof clothing can handle.
And we always show our work too, so that we can all double-check and triple-check each other’s calculations. That way we know we’ve planned correctly and everyone will stay safe.
BTM: So what sort of math should kids learn if they want to work in special effects and stunts when they grow up?
Steve: We use different math depending on what we’re doing, so the more math skills you have, the more stunts you can set up. My favorite math has always been geometry, because I like all its real world applications, and area, volume and angle calculations are the ones I use most.