|How to Jump a Car Like a Stunt Pro, Popular Mechanics, August, 2010|
Some people have a knack.
Travis Pastrana has jumped out of a plane, sans parachute. He has also logged more miles airborne in a car than you've probably spent in first gear. Sometimes, he's merely aloft, like when he set a world record by jumping a Subaru WRX STi 269 feet at 2010's Red Bull: New Year, No Limits event. Other times, he is upside down, like when he executed the world's first double backflip on a motorcycle at the X Games in 2006.
In the microcosm of extreme sports, there are many poseurs. But Pastrana is the real deal. So when PM wanted the scoop on how to jump a car, we knew who to call.
"Anything Can Fly"
Though the Subaru WRX STi Pastrana competed with at the X Games is heavily modified, don't assume you need a specially customized vehicle to achieve liftoff. Pastrana insists that any four-wheeler can fly, adding "We've pretty much jumped everything from shifter karts to buses."
But that's not to say that some cars aren't inherently better at launching and landing than others. "I once did a 50 foot FMX-style jump on a Jeep CJ5, but came up short. Short wheelbase cars are easier to control in the air, but if they bounce [on landing], they flip a lot easier." Fortunately for Pastrana, he installed a roll cage just before the jump, which likely saved him from serious injury. "I was slightly concussed," he admits, "but I was fine."
That's not to say that highly imbalanced vehicles aren't capable of flight. Consider, for instance, Nitro Circus producer Gregg Godfrey, who flew a tractor trailer nearly 90 feet at Pastrana's compound. "All the weight's in front, and it still flew perfect. That tells you that pretty much anything can fly."
Before You Step on the Gas: Math!
When it comes to approach, Pastrana says his technique is specific to the type of car he's jumping. And while weight distribution, aerodynamics, and Newtonian physics are inescapable—even for Pastrana—he insists that, "For the most part, it's just mass and speed. It's math."
There are three parts: takeoff, flight, and landing:
Clear for Takeoff
Too much takeoff velocity, and you face plant. Too little, and you won't even clear the ramp. Launch speed can dramatically alter your landing point, and each mile per hour can translate to as much as 15 or 20 feet. But our guru dictates that acceleration, not just speed, is key to setting up your car for a correct airborne trajectory. "If you're accelerating on takeoff, the front end will raise," he explains. "And if you're decelerating on takeoff, the front end will drop."
When it comes to determining launch speed, Pastrana—at least while setting up for the X Games—says that a dry run on a motorcycle is the best way to ascertain proper takeoff velocity, since it's easier to make mid-air corrections on two wheels. The test jumper's speed is first recorded using a radar gun. "Usually Ken Block, me, or Tanner [Foust] will go first because [the test jumps] can be judged by eyesight." Once an optimum speed is determined, the radar gun's reading is used as a reference for the jump.
After avoiding excessive upward or downward pitch as you exit the ramp, the next task at hand is mid-air car control. No, that is not an oxymoron. Strategic throttle or brake application during flight can affect the orientation of the car, due to the gyroscopic effects of the wheels. "You can probably control the car up to 90 degrees either way," Pastrana explains. "If you're flying normal, you can get the car up to 45 degrees up, or 45 degrees down." Of course, the initial attitude depends on the car's weight distribution. Mitsubishi EVOs, for instance, tend to be nose heavy at takeoff, whereas Subaru WRX STis have a tendency to "fly more level," according to Pastrana.
Mid-air car control is limited by a number of factors, including engine horsepower, polar moment of inertia, and most crucially, drivetrain layout. For instance, high horsepower cars have more juice on tap with which to affect the car's pitch. As Pastrana puts it, "If you're jumping a dog like a [Honda] Civic and give it gas, it's really not going to do anything." For reference, the Subie he recently jumped at X Games 16 had a modified engine that produces 303 horsepower and 451 lb-ft of torque, with a 34mm restrictor mandated for Rally America's Open Class.
While a rear wheel drive vehicle will respond more immediately to throttle application, front wheel drive cars are capable of correcting errant flight angles through steering input, since the relatively heavy, spinning wheels at the front corners can alter the yaw aspect of the vehicle's momentum.
Though front and rear wheel drive vehicles each have their own peculiar strengths when it comes to jumps, all wheel drive cars offer the ultimate level of mid-air car control, since powering all four wheels enables both yaw and pitch correction.
Not surprisingly, there is a limit to the amount of attitude adjustment a car can experience during its brief time between ramps. "In theory, if you had a big nosedive with enough time in the air, you could shift to top gear, rev the engine, and dump the clutch. But you'd have to be in the air for quite some time to pull that off," Pastrana says. In layman's terms, you'll need lightning fast reflexes to make the most of your limited time in the air.
Once you've reconnected with earth, your suspension does the rest of the work by mitigating your vehicle's momentum with immovable tarmac or dirt. Bottoming out is an inevitable in all but the most robust of vehicles, though racers like Pastrana's Open Class Subaru WRX STi rally car (which has been prepped by Vermont SportsCar) come equipped with heavy duty dampers that help absorb much of the impact of landing.
If you've managed to land on all fours after briefly transforming your car into a surface-to-surface missile, congratulations—you've cheated death, and hopefully, injury.
Don't forget that while a pro like Travis Pastrana makes car jumps look effortless, it's taken years of practice to perfect his technique—not to mention so many injuries that he's practically a walking compendium of scar tissue.
Our advice? Save car jumping for video games and leave automotive flight to the experts.