A show of hands, please.
Who here has gone fast in their car? Anyone wound on a ‘dab of oppo’ to balance an intentional powerslide? Burnouts? Skids? I’m going to assume that since we are all like-minded enthusiasts, the answers are a resounding ‘yes’.
For the most part, these skilled maneuvers can be called stunts, and we’ve all seen them performed thousands of times for the benefit of our entertainment on the big (and small) screen.
But there’s one stunt that tends to elude the majority of us enthusiasts, one which elicits a sense of concern for the mechanical sympathy of our cars. The jump.
Forget Hollywood, as we all know the General Lee which blasted the Dixie horn as it leaped over Hazard County lines was not the same car Beau and Luke sped away in. Some poor, orange Charger was bent like a banana for our benefit, a disposable prop unable to stick the landing.
But we all know a landable jump is possible, just ask the brave pilots of WRC and Rallycross who regularly defy gravity in front of a live crowd. Sure, their cars are built specifically for the task, but can you do it with a regular car? A regular car say, like a Mini Cooper…
Cunning Stunts
The Stunt Driving School in Melbourne, Australia says yes!
In fact, they say yes quite a lot as their R50 Coopers have been jumping clients for the past ten years. To put a counter on it, the Electric Blue ‘Skid’ car was built in 2004 and joined the Stunt School fleet in 2009. On a working weekend, it will perform an average of 100 jumps. Run an event about 15 times a year, over a near 10-year period, and the little R50 has defied gravity some 15,000 times.
The best part about this, is that the Minis are essentially standard and are still using their OEM suspension.
For their stunting duties, the cars have been fitted with an electronic speed limiter that makes it easier for first-time stunt drivers to nail the take-off speed of 40km/h (25mph), and the front strut towers have an M7 reinforcement plate installed, but that’s it.
No remote reservoir rally shocks, no mandrel-bent custom tube chassis. The blue R50 even has a full interior, complete with air conditioning and CD player. Even the OEM ‘welcome to Mini’ sticker is still in place!
The cars run the smaller-option 15-inch wheels with 55-profile tires at 45psi, but that’s as much about operating costs and comfort as it is for stuntability.
For what it’s worth, the team tried a Cooper with upgraded shock absorbers and a taller ride height, and while it handled the jumping very well, the change in the center of gravity made the car less manageable in the School’s other activities of spinning through 360-degrees and performing a handbrake stop.
How do they do it?
By the power of trigonometry. Or as you Americans like to say, math!
Education ahead!
The principles of projectile motion are what the team use to understand the way the Mini will travel from the launch ramp, through the air, and onto the downward slope. This makes the transition back to earth as smooth as possible, minimizing any impact to both car and driver.
When you lay out all the data in an Excel spreadsheet, it’s actually quite simple, providing, of course, you understand the metric system. So for readers in Liberia, Burma, and the US, you’ll have to bear with me…
The ramp is fixed at an 8-degree slope which ends about 1.1-meter (1100mm / 3.5 feet) above the ground. With the car approaching at 40km/h (25mph), or 11 meters per second, the incline splits the speed into 10.9 m/s horizontally and 1.5 m/s vertically (up). Remember the whole sin-angle-pi stuff from high school that you thought you’d never need? This is it.
Behaving as any projectile, the Mini follows a parabolic curve from the end of the ramp, and according to the laws of physics, will climb a further 12cm (5 inches) into the air before gravity returns it to the same level it left the ramp, some 3.4m (11 feet) away. Complexities like air density and wind resistance don’t come into play until you are dealing with much higher speeds, so our ‘math’ is actually quite straightforward.
That means the gap between the ramps can safely be about two Tom Cruises apart, but to account for the very technical ‘oh shit’ factor of Stunt School participants backing off the throttle at an inopportune moment, the void is just 2.8m (9 feet) wide. You’ll note an extended horizontal platform here, as the downward slope needs to match the position of the projectile arc.
Total airtime is only 0.3 of a second, barely time to feel that stomach rising sense of weightlessness when the car reaches the top of the parabola or the normal; when the upward acceleration of the Mini cancels out the downward force of gravity.
From there, it’s all physics as the Mini’s vertical velocity slips into negative value and the car lands safely, and softly on the other side.
The maths is so sound, and the theory so tested, that the Stunt School team parked a Lamborghini Gallardo Spyder (height 1184mm, or 84mm taller than the ramp) in the gap, and cleared it with room to spare.
That said, when customers are leaping around, the team install a safety deck between the two ramps, just in case…
So should you grab your Mini and just start jumping things?
In a way I think you may have already. You know those occasions where you hit a small crest or humpback bridge on a country road and feel a split second of weightlessness? That is essentially the same amount of lift you experience in the stunt Cooper.
As when you draw a line between the ramps, the car is barely off the ground at all, and it is only the vision of the gap underneath that makes the jump look more impressive.
Regardless, it is still a great deal of fun, more realistic than Cage’s Eleanor jump, and a testament to the engineering quality of the R50 that makes leaping from ramp to ramp such a thrill.
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Have you ever ‘jumped’ your car? How did it go?
Let us know in the comments below.
The article FEATURE: Yes Virginia, your MINI can fly… appeared first on BMW BLOG
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