Raced a Scion tC this weekend...

[GarySheehan]

It was pretty damned awesome!

[Chris H.]

What the hell?

It's got two wings?

[watkins]

Hey its that thing. Very cool Gary! Facebook tells me you did well?

[theholycow]

What the hell?

It's got two wings?

Word. I'm surprised that it needs a rear wing.

[FDSpirit]

There was a tC in an auto article a while back I read about. Is this the same one?

[AHTOXA]

Looking at this car makes me imagine a front loader with his scoop up.

[ra64t]

nice job, awesome car.

interesting to see what people come up with with an open rulebook. with all the major pro series moving to more spec, there's not this type of innovation there anymore. of course there are pros and cons to either way.

i remember 10 years ago when the talk on all the forums was about chris rado's sub 10 second, sub 9 second production unibody intregra. Then they build one of those crazy pro FWD drag cars with the engine IN FRONT of the front axle! of course now import drag racing is dead!

[fa22raptorf22]

Sure its got a functional front wing...but I sure as hell wouldn't get caught looking like that.

[GarySheehan]

Lot's more photos on my Facebook page.

The gentlemen that came up with the World Racing Scion tC dual-wing design and other aero and mechanical bits have quite a history working with this stuff. Here's some background:

Ron Mathis
Ron is a mechanical engineer with nearly three decades of experience in professional motor racing. He has worked on flagship projects for Audi, Jaguar, and Dodge. While at Doran Enterprises, he was responsible for the ground-up design of the JE4 Daytona Prototype and the American Le Mans Series Ford GTR. Away from the drawing board, Ron has served as race engineer for championship winning teams, most recently with Audi Sport North America. Among many wins and championships, Ron has achieved two 24 Hours of Daytona outright victories and a class win at the 24 Hours of Le Mans.

Barnaby Wainfan
Barnaby is the aerodynamics Fellow at Northrop Grumman, working on both classified and unclassified projects. Barnaby is a leading thinker and teacher of aerodynamics at one of the world’s premier aircraft design firms. Uniting with Ron Mathis on the Audi R10 program, Barnaby has made a lasting impact on that historic sports car project by introducing a new perspective from his experience in high performance aircraft design.

Both Ron and Barnaby have leadership roles at Edison2, one of the finalist teams in the Progressive Automotive X Prize, which is a $10 million competition to build a production-capable, clean, well-performing and safe 100+ mpg car. Very cool stuff, by the way. You can see more at www.edison2.com.

Ron was showing me the downforce data of the car as well as the speed vs. thrust capacity graphs the front tires could support with a given aero setting. I'm not sure if the downforce numbers are confidential, but I will say that the downforce numbers that this car produces at 150mph are SIGNIFICANT for a "touring car".

In fact, one of the most challenging aspect of driving the car this weekend was learning the limits of aero grip through turn 2 and turns 8 & 9. This car sticks at speed and exploring the limits gets much riskier as speed goes up. This was also complicated by the team telling me we were very limited on spares, and chucking the car off the track would most likely end our weekend . Furthermore, we had a few other issues that limited track time quite a bit. Looks like I turned a total of 8 timed laps. Of course there were some out and in laps as well, but not enough consecutive screaming laps to give me the time I needed to feel completely comfortable in the car.

So I turned to Christian's data to help speed up my learning curve. He's got a lot of time in this car with the aero, and his data showed me where the car could clearly carry more speed, even if I didn't yet have the seat time and confidence to find that out on my own.

Christian's data and Ron's advice helped a ton. I ended up turning a 1:22.649 lap at 18psi (we were having some boost control issues and couldn't run huge power). And I know that I was still giving up time in turn 2 and turn 8. I think there's a 1:21 in the car as is, with no further adjustment or power, just driver acclimation. I believe the car could get into the teens with more seat time and big power.

Anyway, I can tell you first hand, the wings work.

Gary

[gizmo]

That's a great post Gary. You are an invaluable asset to this forum. I'm glad to still see you frequent here. I like to think I'm a good a driver (with stick) as I am, many thanks to you.

Since we're on the topic of downforce, I would like to see if I understand it correctly: from what I understand, the rubber compound used in most racing tires, alone, cannot grip beyond 1.3Gs without additional downforce above the weight of the car. With sufficient body effects, ideally a vacuum would be created underneath the car, and that vacuum would provide ridiculous amounts of additional downforce that would make it is very easy to generate far more grip than the weight of the car alone provides. Obviously a vacuum is likely inacheivable, but the notion of generating grip that otherwise doesn't exist from downforce strikes me as a very intriguing subject, as I believe that's the only way formula cars are pulling 4Gs under braking (downforce), because heck knows they have the same tire compound as most other race cars.


Also, do you ever worry about crashing when you are out there driving? Obviously, if I want to win a race and I know other drivers are faster than I am, I need to find a way to push it harder. But it seems like if I'm concerned about wrecking, I never quite bridge that gap. And in talking with my instructors, who race professionally, they all say that if i'm worried about the cost of the car when i'm driving then I might as well pull in the pits and quit. Obviously, you naturally push the envelope without much trouble, but I was just wondering how cost comes into play when you're running confident but still trying to reduce your lap times.

congratulations again.

[theholycow]

Mind if I cut in?

With sufficient body effects, ideally a vacuum would be created underneath the car, and that vacuum would provide ridiculous amounts of additional downforce that would make it is very easy to generate far more grip than the weight of the car alone provides.

A 100% vacuum, which the underside of a car could never come close to, would provide 14.7psi on the sky-facing area of the car (at sea level). A tC would have 176,744 pounds of downforce.

I believe that's the only way formula cars are pulling 4Gs under braking (downforce),

Formula 1 cars have enough downforce, theoretically, to drive upside-down...though I don't know if anyone has tried it. Youtube has what appears to be computer simulations.

heck knows they have the same tire compound as most other race cars.

When I used to watch NASCAR, tire compound was a strategic choice, not a standard. Of course all the compounds used were racing compounds, but they varied enough that some teams could choose a compound that meant having to pit fewer times during the race, while other teams would choose a stickier compound for better cornering. The result was competitive both ways. I haven't watched in 13 years or so...so maybe things have changed.

they all say that if i'm worried about the cost of the car when i'm driving then I might as well pull in the pits and quit.

There's always going to be someone who cares less than you. In fact, there's always going to be lots of people who care less than you do. Some of them are also at least as good at driving as you are. They will usually beat you.

[theholycow]

Do you mean manhole covers? Those weigh over 100 pounds. F1 cars still have that lame fiberglass nose that offers zero protection to drivers who routinely end up with crushed feet, right?

[LHOswald]

F1 cars generate enough vacuum to rip pothole covers off the road. That's why they have to lock them down on road courses. Apparently there was an incident (in the 80s or 90s, can't remember) where one car sucked the cover off the road, and it hit the car behind it. That was that long ago... imagine how much more vacuum/downforce it coudl generate now.

Do you mean manhole covers? Those weigh over 100 pounds. F1 cars still have that lame fiberglass nose that offers zero protection to drivers who routinely end up with crushed feet, right?

+1 if he means manhole covers. but he said pothole covers...maybe the stuff they use to repair gashes in the road? but locking that stuff down doesn't make any sense. enough of a vacuum to pull up a manhole cover is absolutely ridiculous

[ra64t]

here's my input

about downforce and grip i'm no physicist or aero engineer but I think the amount of force the tire can hold to the road is dictated by many more things then just the grip from the tire, but also the size of the contact patch, surface type, suspension (it's ability to distribute the force to different corners of the car for example), weight of the car, etc. etc. As a reference in the rx7 on old shaved r-comp tires, which are pretty much as close to a racing slick and still DOT legal, I saw a max of 1.2-1.3gs cornering. In the skip barber formula car on full treaded street tires I saw a max around 1.4-1.5gs cornering. Both these cars have minimal downforce.

downforce, whether generated by "ground effects" like a sculpted underbody or rear diffuser, or by wings will obviously increase the amount of grip by "pushing" the car down to the ground. Modern f1 cars are required to have flat bottoms so little of the downforce is generated from a "ground effect" producing vacuum under the car; most of the downforce comes from the wings. Due to rule changes, a current F1 car does not necessary generate that much more downforce as one from 20 years ago as you may think.

Modern F1 cars do not have a fiberglass nose, but rather a carbon fiber one. Rules indicate the amount of crush space between the nose and the drivers feet and there are usually multiple bulkheads in this space to protect the drivers feet. They are much safer then the nose designs of 20+ years ago, when there was much less space between the feet and nose, and often either no crush space (just a rigid steel spaceframe) or just a flimsy aluminum monocoque which disintegrates to a major impact. The sketchier designs are still used in the lower levels of racing today - I would know, I've driven them.

[theholycow]

I agree about grip, and I'm glad to hear they've improved F1 safety.