Interesting Batmobile fact

[corsachili]

I'm a collector of automobilia and motorsports literature. Generally, I'll collect magazine articles, posters, and ads of motorcycles or cars that I own. And so over the years I've been collecting magazines that feature CSLs and building a small library. I was recently perusing the October 2005 issue of Octane magazine, which featured a story of a Batmobile vs. a Carrera RS, being driven at Spa Francorchamps of all places. One of the interesting facts mentioned in the story (other than the point that RSs go for insane amounts of money compared to Bats, despite many more being made) was that the body kit fitted to Bats reduced aerodynamic drag by 16% which they claim is an equivalent to a 50BHP gain. I don't know if that's true, cause I'm not an engineer, but if it is, that's pretty compelling.

 

[x_atlas0]

That number depends on the speed. The higher the speed, the more the aerodynamics come into play, both in terms of lift and drag.

Based on my understanding, they made the bat kit not so much to reduce the drag, but to reduce lift. As you may have noticed, the front of the E9 isn't exactly good at keeping the front planted at high speed, due in part to the shape. Much like many of the cars of the time, while the shape is pretty, it also causes lift at speed. Putting the bat kit on the car significantly reduced front end lift and increased downforce in the back via the three primary spoilers. (roof, duck bill, and triple-support)

 

[timt]

Downforce, or lack of it was the key problem. In his 1979 book Walton quotes Braungart, BMW, as saying that the standard car "had rear end lift of about 60 kg at 200 kmph (approx 124 mph)". The wing converted this to 30 kg downforce and reduced the Nurburgring 14 mile circuit lap time by nearly 15 secs a lap - from behind the Capris to well in front! The dramatic benefit of the wing was reported in the motorsport press at the time - but many, many years ago now. The wing also helped them solve other problems and reduced drag, a little. So even at less than 200/124 k/mph there is some benefit in the rear wing although not much below say 130/80.

Before I put my front spoiler on I didn't feel any "lack of confidence" in the front end although the rear end was always feeling light - even at low speed where pure physical weight was lacking versus the front. The bonnet (hood) lifted slightly at speed but that was on the fixings although clearly indicated pressure in the engine compartment, and therefore lift, subsequently reduced by the spoiler.

PS Spa-Francorchamps is much loved in Europe and rated by drivers as one of the most challenging circuits post the Nurburgring. Sadly it too has been slightly emasculated but is still hanging on in the Formula One calendar though far more interesting in saloon cars!