Answers To Unanswered Questions

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Last Saturday, I ran a series of “unanswered questions” and asked for readers to help answer them. I was pleasantly surprised at the comments and e-mails that I got over the next few days. Many people requested that I publish the answers that I got. After a week, I’ve decided to post some of the answers. As a refresher, I’ll post some of the questions again. Thanks to all that participated.

First, a couple of aerodynamic questions – with all of the speculation of the new exhaust outlets being the culprits of the lack of racing, I got to wondering about some other things possibly making a difference in aerodynamics. First of all…if a wickerbill can make such a huge difference, what about the camera that is mounted on the end plate of Dan Wheldon’s rear wing. Yes, it’s small but it isn’t flush. Could this cause significant aerodynamic drag on long straightaways? I also wonder about the “flat” (non-glossy, non-polished) paintjob that the William Rast cars have carried (i.e. Ed Carpenter’s car this weekend). So much care goes into make a car slip through the air on straightaways. Does a flat paintjob produce more drag than slick polished finish?

Does Dallara still build these current cars or are there just a finite number of these cars available?

When a car crashes on a race weekend, how do the teams get the car repainted so meticulously? I know they use a lot of decals, but are there any type of painting facility that the teams use? Or is there no painting involved at all?

On consecutive race weekends like we are in right now? Did most of the teams take the cars straight from Watkins Glen to Toronto, or did they take them back to their respective shops?

Do the drivers stay in their motor homes at all of the tracks at every race weekend or just Indy?

Why did Justin Wilson run the first race this season in Dale Coyne’s #19 Sonny’s BBQ car, then switch to the #18 Z-Line Design car for very race since?

Why is Robert Doornbos running McDonald’s livery now? Did McDonald’s put up additional money?

Now, here are some of the answers I received…

From Jim in Wilmington:

A wing produces lift (and drag) by turning the airflow from its original direction (forget all the Bernouli stuff you were taught in grade school). The more the flow is turned, the more lift is produced. A wicker really acts like a tiny flap on the trailing edge of the wing and kicks the flow up a last little bit. It changes the lift and drag coefficients. Lift is calculated by multiplying the lift coefficient times one half the air density times the air velocity squared times the wing area. Since the wing area is fairly large any change in the lift coefficient has a significant affect. In the case of the camera pod, the drag produced is what is known as form drag. The formula is similar the lift formula except for a couple of things; you substitute the drag coefficient of the form for the lift coefficient and the area you use is the area of the device. Since the area of the camera is small, so is the affect. I have to confess that I hadn’t noticed Wheldon’s camera. Does this mean that he doesn’t have the normal Dallara camera o top of the air plenum? If so and the area of his camera is smaller, it may be an advantage. It shouldn’t affect the performance of the tip plate.

Incidentally, the tip plate’s mission in life is to fool the air into thinking that the wing is longer (long thin wings are more efficient) than it actually is. It does this by breaking up the flow of high-pressure air from the top of the wing down to the low-pressure air on the bottom of the wing. This flow forms a vortex, which trails behind the car and creates a lot of drag and is identical to the wing tip vortex that forms behind a large airliner that can actually flip a small plane following in its wake.

Finally, there are opposing theories on the affect of rough paint. However, most sources agree that as long as the roughness is thinner than the boundary layer (the thin layer of air next to the surface of the car that is not moving relative to the car), it has no affect at all. The kicker is that the boundary layer gets thinner as the speed increases. I know that when I used to wax my small plane, I could never see any affect at all on speed. On the other hand, during World War II, the British had some special DeHavland Mosquitoes (400 mph top speed) painted with a special radar absorbing paint that was rough and reduced their top speed by 40 mph! My guess is that the affect on an Indy car is minimal.

Tim In Florida writes:

My understanding of the paint issues is that there is a fairly recent development in graphics technology where the cars are covered with a vinyl paint replacement the colors graphics and stickers are all incorporated in a thin light protective WRAP that bonds to the car surfaces. The final product is lighter than paint and stickers and can be applied with amazing speed on site. I think I saw something on cable about it. Some call it superwrap but a team with revolving sponsors can change a car over in a few hours…http://www.motorsportsdesigns.com/ Dallara is still building and selling IndyCars….the prices are fixed ($350,000 I think) http://www.dallara.it/ The cars are periodically refined with the latest updates, so the newest tubs with all the updates incorporated are slightly lighter than tubs that have been updated after manufacture.

JP writes:

Could be a couple reasons why NHL added McD’s stickers to Doornbos’s car. It is sponsorship silly season and with Newman gone – the sponsorship may not be guaranteed anymore. The second car could be a show of good will for negotiations (like Will Powers Verizon car) or to increase the likelihood of recall if there is any research being done based on brand recall from these races. I think NHL may be pitching a deeper relationship with McD’s around activation of Graham in some sort of endorsement role. Leading up to the race, the restaurants in upstate NY were distributing cups with Graham on them. Perhaps a trial balloon for a wider campaign next year that follows the series from market to market or nationally around May.
I suspect if they get McD’s on for both cars, they may have to find someone a little more cordial and less apathetically disinterested than Robert has been this year. With the likely race(s) in Brazil next year it could be someone that MdD’s could activate down there.

And finally, Brian in Malaysia writes:

After most races, racecar transporters/mobile shops are driven back to bases in Indy (or elsewhere) for resupply and to offload cars for rebuilding/repainting. They’re seen departing racetracks a couple hours after each race unless a Monday test day follows. Even then, one of a team’s two transporters will likely roll back to Indianapolis.
Drivers’ employment contracts provide for hotel rooms at/near race venues. Owned or leased motor coaches in Indy’s infield are a sensible exception for 3-4 weeks.
NHL Racing likely applied McDonald’s decals to Robert’s car rather than run a plain black car or one reading only, “Hole In The Wall Gang Camps” or “Your Ad Here.” Probably fostering some feel-good with McD’s marketing czar(s) after Mr. Newman’s passing and Sebastian’s departure. Maybe McD’s trickled-out a little extra money if it was told that Bobby D. is a hot shoe who might get his car camera time.
After Justin Wilson and Bill Pappas and the rest of DCR performed in Saint Petersburg, Z-Line was likely urged to $tep-up $pon$orship.

Thanks to all of those who participated. It was a fun, yet educational exercise. I was especially intrigued with Tim’s comments about the “superwrap”. We’ll do this again soon.

Since we have no race this weekend, there will be no article as I’ll take tomorrow off. I’ll be back Monday with a special article of a slightly different nature. Enjoy the weekend.

George Phillips

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