The RACER Mailbag, March 9

The RACER Mailbag, March 9

Insights & Analysis

The RACER Mailbag, March 9

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Welcome to the RACER Mailbag. Questions for any of RACER’s writers can be sent to mailbag@racer.com. Due to the high volume of questions received, we can’t guarantee that every letter will be published, but we’ll answer as many as we can. Published questions may be edited for length and clarity.

Q: When it comes to whether or not IndyCar will have an entirely new chassis in 2024 when it goes hybrid, it seems that we have an incredibly short timeframe to realistically make that happen. Is there any chance that a manufacturer like Dallara has had team members doing some side-of-desk, “Suppose we came up with a new IndyCar…” plans they could pull out and present on short notice?

Matt Philpott

MARSHALL PRUETT: Jay Frye told me late last year that ideas for the next car have been batted around with Dallara, but I couldn’t get a definitive word as to whether that meant lines had been drawn in CAD or if it was concepts done in crayon on a napkin over lunch at the Working Man’s Friend (that’s more my style). A lot of initial work could be done right now, but until all of the final weights for the hybrid drivetrain components come in, it would be hard to make key decisions on packaging and placement of the componentry to create a favorable front/rear weight distribution.

Q: YouTube has live coverage of WEC, ELMS and AsLMS races (including practice and qualifying sessions) and I suspect a number of your readers would like to know that it’s available. The coverage is free to watch (as in no fees) and is also commercial-free.  The commentary is informed, knowledgeable and excellent.  If you subscribe to the various YouTube channels, you can watch all of the races in replay — either the full races or highlights — which is a nice option if you don’t want to get up at dawn (or earlier) to watch live.

Gordon Taylor, Asheville, NC

MP: If there’s one segment of racing fandom that tops the others in regard to knowing how/when/where to get their international endurance fix, it’s sports car lovers. Thanks for the prompt here, Gordon, for those who want to join in.

Q: Hey Marshall, maybe you or RACER can get a request to Mr. Penske about the inability of RE scanner owners to get the radio frequencies “over the air.” This is affecting countless numbers of IndyCar race fans. Having to manually input the frequencies is antiquated. Surely an agreement can be had to provide this service at each track for RE scanner owners.

Jeff, Florida

MP: I’ll be honest, Jeff: of all the things I’m going to bug Roger about, this isn’t one of them. He’d send a drone strike my way if I started bothering him about radio frequencies. His communications team are aware of the suboptimal situation since Racing Electronics opted to discontinue supporting the series. If having to manually input frequencies is what’s necessary, I’m sure folks will spend the time to do so. It isn’t great, but it isn’t the end of the world.

Q: For NASCAR, “Drivers start your engines” is certainly OK. But for IndyCar? No! Here’s how to do it right and consistent with the ‘Gentlemen…’ call back in the day: “RACE TEAMS START YOUR ENGINES!” 

I’ve never seen an IndyCar driver start an engine for a race, at least by himself.  When women weren’t in the pits “gentlemen” was technically correct, but it was never the “drivers.” Even so, in NASCAR, I’d call them “racers,” not “drivers.” Hell, I can drive a car.

I hope Roger fixes this before Memorial Day.

John Langston, Edmond, OK

MP: We’re three consecutive Mailbags into the “What to call the starting of an IndyCar” conversation. Can we make it an even four?

You can tell by the expression on this kid’s face that he’s just tried using his scanner. Michael Levitt/Motorsport Images

Q: I read your recent article on the growing support to introduce a new Dallara at the same time as the delayed hybrid power units with great interest. Two questions: First, what’s the drop-dead date for a decision to allow enough lead time for Dallara to design, test and manufacture enough units to be ready for the start of 2024? I’m sure cost will enter into the decision. What’s the cost of a new chassis versus the cost of adapting the current DW12 to the new power unit?

Bill Carsey, North Olmsted, OH

MP: I reached out to Dallara with no luck on the first question, and since you read the article, you would have seen the projected DW12 upgrade costs and a suggested new-chassis cost. But since a new chassis has not been commissioned, there’s no way to answer what it will go for.

Q: Can you explain what in-car sensors the engineers in the pits use to calculate CoP, what the ideal location is, and the adjustments they can make to move it around?

Also, I noticed there are several back to back weekends in this year’s schedule. Robin often wrote about the burden this put on crew members. Could you explain what a typical week’s schedule looks like for them and how this changes when there’s no open weekend between races? 

John from Madison

MP: I’ll handle the first one and fire in the second a few weeks from now; the Mailbag is already overflowing with post-St. Pete and topical questions.

For those who are reading about Center of (aerodynamic) Pressure, or CoP, for the first time, it’s a measurement where the focal point of downforce is positioned on the car. If you look at an IndyCar from the side, it’s the point fore or aft where the downforce is most concentrated. Front and rear wings are used to tune CoP with an increase in front wing/decrease in rear wing moving the CoP forward towards the nose, or a decrease of front wing/increase in rear wing moving CoP to the back. There are other factors to consider, such as spring rate, third spring/ride height control to limit or allow CoP to move, plus the use of strakes in the diffuser and other aero options at the various tracks, etc., but the topside wings are the main tuning tool for CoP.

A CoP number is generated through the data system with strain gauges (also known as load cells) placed in the car’s four corners inside the suspension pushrods. The aero weight (downforce) shown across the front axle is compared to what is being generated across the rear axle, and with some quick math thrown in, a channel that calculates the front/rear weight gives teams a CoP number to track and use to make adjustments as the driver or tires needs.

It’s easiest to get clean CoP data when a car is on the straights, but less so entering and navigating through the corners thanks to bumps, curbs, and big braking or acceleration moments that mess with the strain gauge data. To help remove those braking/cornering/accelerating disturbances, teams will use data from their G sensors (acceleration sensors) to filter out those events as much as possible and generate clean-ish CoP numbers in the corners.

There’s no magic CoP number since we go to all manner of tracks in a variety of wing/downforce packages.

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