BUBBLE VS PEEL
I listened to the story about the stickers on Sebastian Saavedra's car blowing off during practice make the rounds all week, but I asked Dragon Racing team owner Jay Penske if that is indeed what happened to his No. 6 car that was chrome blue before the chrome blue blew away.
“No, actually, it had nothing to do with stickers or a [car] wrap,” he told RACER. “It was paint. We wrapped [Sebastien] Bourdais' car in the chrome and red, but Saavedra's car was actually a new paint process that went wrong.
“There was some sort of curing problem that we discovered after it came off; the paint didn't adhere to the bodywork properly and it formed tiny bubbles everywhere. However it happened, something allowed the paint to start to separate from the body and then it all went.”
Saavedra has been sporting a plain white livery since the incident.
INSIDE POLE AND RACE DAY ENGINEERING
Teams spent the better part of a week working on their race day chassis and aerodynamic setups before switching to searching for outright speed for Pole Day. With two distinctly different approaches to finding stability and consistency for the race and bad-fast pace for time trials, I asked Simon Pagenaud's engineer how teams go about executing both performance programs shortly before they went out to qualify.
“For race day, we basically, we run all week basically trying to find out what level of downforce we need to run in traffic and then we adjust based on ambient conditions for the race what the wing angle it is,” said Schmidt's Ben Bretzman, who worked previously worked with Pagenaud at Highcroft Racing.
“So the big thing for qualifying is: can you get all the drag off the car and still be flat for four laps? Another issue you start running into in qualifying is: as you pull drag off, is your car good enough or does it start scrubbing speed? You might be able to run around flat but it's going to slide around more, and is it faster or slower to do that? Right now we're to the point where we've got the wing all the way laid back and all the wickers off the car and it's just kind of see what she's got.
“One thing we can play with is basically the attitude of the car, the rake, to try to get drag out. You start messing with how is the downforce made by the underwing? That's a big thing – where do you want to place the ride heights mid-corner in qualifying, and basically down the straightaway to get the most drag out of the car? Whereas, on race day it's all about getting the most efficient downforce you can possibly make.
“Another thing you'll see people doing, you'll see front wing end plates angled down, angled level. That's all a little bit of drag but it's also just kind of balance shifts from where your car is at.”
For qualifying, most teams remove the wickers off of the front wing and atop the underwing tunnel exits, as well as tilt the rear wing back as far as permissible – negative 10.5 degrees. Teams also run the front wing in the range of negative four degrees to shed downforce, along with using various radiator inlet blockers.
A newly common practice of removing one or both underwing sidewall exit pieces – effectively shortening the length of the tunnels – was seen in qualifying, with most teams pulling one wall and a few, including the Team Penske cars, pulling both, resulting in something like 300 fewer pounds of downforce.
Power held on for dear life in qualifying, but also used that same both-walls-off setup to set the fastest speed during the top 24 on Saturday. With so many variables, it's hard to always hit the right setup based on the weather conditions, and as Bretzman explains, there are certain handling and performance goals an engineer strives for, but driver preference is also vital.
“Yeah there's a definite difference between being oversteer and being free,” he said, referring to what he tries to give the fearless Pagenaud. “The key is to get the car as free as you can without going into oversteer. So yeah, you can mess with tire alignment, you can mess with tire cambers, which will certainly help the car free up; you've slightly reduced contact patch on the tire, so how well you can use the smaller contact patch to try to gain speed?
“Those are all aspects if you run a stiffer car or softer car; a stiffer car will certainly not move as much and you certainly don't get as much ride height variation from straight to corner then. And so if your right height variation is lower you can kind of set your platform better. But you do give up trim from it. Certainly, what we found with Simon this week is: where's his oversteer versus where's he free, and I think he's got a good idea of that now.”
Bretzman has an additional engineering aspect to consider, and that's his driver's supreme adaptability. With his background in everything from sports cars to rallying, Pagenaud is known for being able to drive a car to its limits even if it's not handling to his liking. That bravery, while certainly an asset on a road or street course, is something his engineer does not want to trigger at Indy.
“Yeah, you have to manage expectations here,” said a smiling Bretzman. “You have to really respect Indy. We're able to look at numbers on the computer to understand where his balance is at. And so we make sure we never overstep his mechanical balance or his aero balance. Because he'll go out there and if you tell him to be flat, he'll be flat...
“He does not overstep the bounds of the car as we see it in the data, and trust ourselves as engineers not to get too aggressive with it. He is very good at feeling what the car is doing. And this week he's learned so much. He's so confident now. That's the other key: managing his confidence level.”
The final area of Pole Day engineering Bretzman touched on was running on low fuel levels. Every team looks to save weight and increase speed by running the bare minimum amount of fuel, but how far does that limit get pushed?
“I wouldn't say it's the drop but we definitely go to the edge of the envelope,” he confirmed. "Obviously, you saw a couple years ago you can push the envelope a little too far and run out of fuel, and you don't want to make that mistake. But we'll be within two-tenths of a gallon [left in the tank] when he crosses the line…”