Factory 48

[nulrich]

Yeah, but then I have to RAISE the whole rest of the car 1/4 inch. A thought experiment: would that make the CG higher or lower?

(And if you don't have to raise the car after adding the 1/4 inch steel plate, then you were running it too high in the first place!)

Nathan

[RussMcB]

If you already have rub blocks/plates, there is no ride height penalty for making them larger (more surface area, not thicker).

This sounds like a pretty good idea. Not only do you get all that weight as low as possible, you can really protect the bottom of the car.

I like having robust rub blocks. Less cringing when you scrape bottom.

Damn the torpedoes (curbs)! Watch out. I'm coming through. :-).

[john f]

Yeah, but then I have to RAISE the whole rest of the car 1/4 inch. A thought experiment: would that make the CG higher or lower?

(And if you don't have to raise the car after adding the 1/4 inch steel plate, then you were running it too high in the first place!)

Nathan

the cg heigth is going to be somewhere in the 10"-16" range. if you raise the car a 1/4" and the add 100# at a heigth of about 2" your overall cg heigth will be lower. also, as stated by RussMcB most cars have some sort of rub blocks on the bottom that are at least 1/4" thick so you replace them with the plate. years ago when i needed ballast i used large chunks of steel plate or bar to make min weight and also balance the car the way i wanted it.

john f

[nulrich]

Sorry, I stated the problem poorly. You are of course correct that adding a 1/4 thick steel plate to the bottom of the car and raising the car to compensate will lower the CG height.

But adding any sort of ballast will lower the CG (assuming it's below the CG). The real question is what is the best way to add weight? Adding 100 lbs of lead just above the existing floor without raising the car will lower the CG more than adding the steel floor and raising it up to compensate.

There are aero implications to changing our rub block configuration, don't want to go there.

I agree that a steel floor is nice, but we already have that. Just making it thicker is one option. I'm leaning towards thin sheets of lead in certain places, which both lowers the CG and allows us to change the weight distribution (front/rear and side to side). 1/2 thick lead sheet weighs about 30 lbs per square foot, so that's still a lot of lead. One more parameter to optimize.

Sorry to hijack the thread.

Nathan

[captaineddie1975]

How about 100-120 lbs of ballast? Trying to figure out how to place that safely has me scratching my head a bit, although I've got a couple of ideas. Of course, we won't need that much for certain unnamed drivers but there is one 150 lb kid who'll need a lot of lead in the car! I don't see anything prohibiting depleted uranium in the GCR...hmmm.

Nathan

Pardon my ignorance but wasn't spent Uranium used in the armor piercing shells for the tanks that did so much damage to enemy tanks in Desert Storm and wasn't one of the problems that soldiers who had helped to load shells got sick later? Do we really want spent uranium around us in racecar chassis? I thought I knew what Tim Richmond died of but after Froggies comment how long had using spent uranium in Nascar chassis been going on?

[Purple Frog]

Let's be clear here, spent uranium was never legal in NASCAR.

NASCAR only allowed ballast to be installed in the two square frame rails that run along the bottom of each side of the chassis between the wheels.

But, if one were to machine a chunk of 'metal' down to fit inside a chassis tube, before the chassis was welded, engineers could strategically place ballast where they wanted it. Until they were caught. Usually detection was through the inspection of crash damage.

NASCAR cars are stone axes, but they are highly engineered stone axes.

Their fine system is highly inventive. Suppose your team was caught cheating in a Cup race back in the early days of Grand Am taking over the Daytona 24 hour. Well, you could pay a hefty fine... or maybe it would be waived if your popular driver decided to race in the Daytona 24.

[jim morgan]

So that's why everything glows purple.

[Purple Frog]

The purple glow is from the neon lights i mounted in the diffuser tunnels.

OBTW, I heard on the 11 o'clock news that two refugees crossed into Georgia on I-75. One appeared to be Ho Che Min's great grandson, the other a door-hanger from Central Florida. It is belived they had to un-titled cars in a trailer, and were last seen speeding north around Macon.

Beartrax, i see you lurking. Are you jealous of your father getting the opportunity of a lifetime this weekend?

[Beartrax]

Beartrax, i see you lurking. Are you jealous of your father getting the opportunity of a lifetime this weekend?

Frog, at 12:27am I was in bed. I guess Apex had not logged me out. Gotta work in the morning you know.
In response to your question, I am, as we say in New England, Wicked Jealous. I wish you the best of luck this weekend and hope y'all have a great time.

I had a nice time crewing for "RobLav" at Lime Rock last weekend. Hopefully Fat Boy Finelli will run with the F2000 circus at Lime Rock and Watkins Glen. If he doesn't, I'll have to make my self available to another team. Need to get my fix of race fuel fumes!