AI Aerodynamics Discussion

[Jeff F]

My $.02:

 

Disclaimer- I'm in the "very little aero" club. Just an airdam under my radiator, and a grille opening blocked off: http://hyperperformance.smugmug.com/gallery/4962878_rhUzr#297692521_kkxKm-A-LB

 

I don't mind seeing rules that close up areas that could be potentially expensive/advantageous that haven't been explored yet. (Don't call it a loophole. A loophole is a way to skirt (pun intended) around something. Right now all the aero is legal). But even though it doesn't effect me, I don't want to see rules put in place to take away what other guys have done, such as skirts, splitters, etc. Why should we tell Jay Andrew he has to remove his skirts or rear diffuser-looking-thingy, or Mark Luna that he has to trim his splitter, or Ryan Walton/Agent47 that the Fox side skirts that they developed and have tooling for can't be used??? That's a good way to drive off longtime participants and supporting series sponsors.

 

Why not come up with a set or specs that allows everything out there, but keeps it from getting any further out of hand:

 

-Any splitter/airdam is allowed, but must not extend more than (insert number here)" outside of the bumper profile as viewed from above.

-Splitters/airdams must end at the front axle centerline

-No mimimum height on airdams or splitters. There are aleady splitters out there that are very close to the ground. (My airdam is made of cheap plastic and is sacrificial, it just wears away and I replace it every so often)

-The only aerodynamic devices allowed between the front and rear axle centerlines must not be any further inward than the inside of the front tires. This allows any kind of side skirt, but gets rid of anything that uses under-car air flow.

-Aerodynamic devices on the rear, with the exception of wings/spoliers, must remain within the rear bumper profile as viewed from above. No minimum height. Might need to make some clarifications to prevent non-stock rear bumper covers that stick way out, as this is a potential loophole for diffusers as well as wings.

-Keep existing rules for wings/spoilers

[swhiteh3]

"My splitter does stop at the CL of the front axle, but my belly pan starts there!"

Good catch. My intent (and I *assume* the intent of BPT as well) was that this rule wording was in addition to the "no aero modifications, including belly pans behind the rear axle CL" sentence. That sentence should have appeared in the above proposal, but it did not care because I was careless. Sorry.

[horsewidower]

A 3" minimum height rule requirement causes me to have to raise the front of my car. Thus requiring me to rerun the geometry calcs, possibly causing me to have to R&R the suspension mounting points, and on and on. I proposed 2". Other than that item, I like the way the discussion is going.

 

Bob

[ST#97]

A 3" minimum height rule requirement causes me to have to raise the front of my car. Thus requiring me to rerun the geometry calcs, possibly causing me to have to R&R the suspension mounting points, and on and on. I proposed 2". Other than that item, I like the way the discussion is going.

 

Bob

 

I second the 2" rule for min height....for reference my 2000R nose is 1 7/8" off the ground with the wear plates under it and I am still 1/2" from getting to min ride height....

 

Just data for reference.

 

I also like nothing in a "box" between the axle centerlines and side pinchwelds, no rear diffusers and nothing related to removing the trunk well and installing a revised fire wall under the vehicle like the WC cars... The GTO at nationals this year had me a little peeved about how they were exhausting air from the rear of the car....

[pbr96]

I don't have a dog in this fight, but one of the rules another series used was that "no part of the vehicle can touch the ground with 2 tires flat on either side of the vehicle." My wording may not be exact, but it's simple and easy for everyone to check. I think part of the rule was from guys damaging the race tracks with suspension, body and exhaust components with flat tires from offs or contact.

 

Carry on.

[SNAKBITN]

Thats to simple it will never work

[swhiteh3]

Thats to simple it will never work

I'd say it's ANYTHING but simple. (And of course, this is not aimed as Paul, since it's not really his recommendation....) You need to know how low a flat tire goes. Do you deflate the tire completely and risk damaging the tire to prove a point? Not to mention the hassle of deflating tires on every car that goes through tech.

 

No, so you need to know how low the tires can go. So for every combination of tire size and wheel size, you need to measure how low the tire can go. For simplicity you might be able to get people to agree to just consider the edge of the rim, but I'm sure someone will (and rightly so) argue that the car will not go all the way down to the rim with a flat (but still intact) tire.

 

Now you need to use some reference pressure for the tires going through tech. Because if we determine my tire and wheel combination drops 2" when flat (just for arguments sake), then I could simply add another 10 or 20psi when I go through tech to increase the radius of the tire slightly and get whatever my questionable component is to clear the rule. Sounds silly, yes?

 

Now how about the idea that when two tires on the same side go flat, the whole car does not drop that "agreed upon amount". The car only drops that amount along the CL of the two wheels (approximately). Outside that point it drops slightly more than that, while features along the CL of the car (say the transmission) only drops about half that amount. Getting confusing yet?

 

Sure, I'm nitpicking details. But the first time someone is DQ'ed for this rule, you don't think they'll start nitpicking too??

 

I see the intent of the rule, but it's enforcement would be nothing short of a nightmare, in my opinion. However, preventing components from digging in or dragging is yet another advantage of having a minimum ground clearance rule.

[pbr96]

Well Scott I can tell you from past experience with thus rule I can't think on a single instant that it was as difficult as you say. I know it was used in a pro series for about 10 years, and then they went to a 3" ride height on everything. They would spend countless hours rigging up scale pads with blocks and levels along with other test pieces at exactly 3" that the cars had to be pushed over with the driver in place, the tires set at a certain pressure and a fuel level. Think the crews liked pumping out the tanks and jumping through all that, they all wanted to go back to the tire deflation test.

 

On the tire deflation test, the tech guys would randomly pick a car or cars in tech, pull the valve stems out of one side of the car (left or right side only, not the whole car) and when it stopped bleeding off they would check. I never damaged a wheel and can't think of anyone ever claiming that there $1500 magnesium BBS got hurt doing this or even pop the bead. Yes you do need to refill the tire, some have bubbles or nitrogen tanks and that adds a little, but as far as the car goes, this is simple. Besides, don't you think you should know if your car could limp back to the pits on two flat tires instead of being high centered on you body work or another extremity?

 

OK, back to the cheap seats. If nothing else you guys are entertaining.

[swhiteh3]

I didn't think it would harm a wheel, but rather a tire. Sidewalls generally don't like to be pinched over that much, but if it was done for that long, maybe it's not an issue.

 

In Grand-Am we always used a set ride-height rule. It was very simple to enforce by sweeping a bar under the car while it was on the scales. The scales need to be set-up anyway, don't they? Done just before, or just after a session, it was expected to pass regardless of the fuel load or tire pressure at the time.

 

How were the WC guys making any more complicated?

[92MNstanger]

It was very simple to enforce by sweeping a bar under the car while it was on the scales.

 

 

Wouldn't this give a roughly 2" ride height advantage to the Griggs cars with throught the frame SFCs vs the MM SCFs? Wouldn't this also encourage people to cut/weld new exhaust that exits through the body work to keep piping tucked up nice and high? The current rules allow floor mods for exhaust clearance (7.3e).

[swhiteh3]

The quote you chose was from my discussion of Grand-Am enforcement and WC enforcement.

 

My previous posts make it clear that there might need to be certain things that need exemptions, such as low hanging exhausts. Personally, I think people should be able to move these things up above the minimum, but I understand people don't want to re-fabricate things that they've already done.

 

My intent certainly is not to outlaw existing common aftermarket parts, which is why I included things like torque arm mounts in my list of possible exceptions. I would not think that subframes would be an issue, but if a concensus about a 3" rule, causes an issue for certain SFC brands when cars are at the current minimum ride height rule, then yes, SFCs might need to be added to the list. But I would certainly want to do everything possible to make this list does not become any longer than it needs to be.

[ST#97]

Again for reference from my car....exhaust, MM g-load brace, K-member and SFC's are LESS than 2.5" off the ground and I am NOWHERE near min ride height as currently measured in the rules....I am using all stock/repro parts, nothing a 2000 R would not have had.

 

Leave the under car stuff alone and have a 2" min on the splitter... Nice and simple and won't cost any current racers any money!

[D Algozine]

My thoughts listed below are going to have to be written better, but here's the basic principals.

 

Splitter -

Min 2" ground clearance

Can not extend rearward beyond the center of the front wheel

Can not protrude more then 3" from stock location of front bumper cover

Must not be wider then the track width of car. Also, no pieces wider then the track width, ie, canards, splitters, etc..

 

Underside of car

No aero compontents from the mid point of the front wheels back. ie, flat panels, diffusers, canards (sp), etc....

 

Wings

Current rules

 

Front bumper covers

Must appear stock looking from the middle of the bumper upward. Modifications below the mid point of the bumper cover are ok, as long as they meet all other rules.

 

Have at it !

[horsewidower]

What's the purpose of the proposed bumper cover rule?

[onralz]

I've kept out of ALL the rule discussions here because I don't think it matters. It's just semantics unless they are able to be enforced at EVERY race. That's not going to happen with the current numbers of people working the events. At least not here in the Midwest. I'm not blaming anyone here. Just presenting the reality. Our director and his people work hard at every event and I appreciate the work they do. They simply can't do the enforcement needed with their numbers.

Do we have dyno's at every race? No. Is there someone checking the AI blocks to make sure the 302 based ones aren't aluminum? no. Is anyone measuring anything? Very rarely. So what's the point in debating some of these rules? These are rules in place now and they aren't being enforced.

 

For the record. My AI car would fit in the rules proposed here. My front bumper is stock dimension GT bumper cover. My aluminum splitter is 4" from the outside lip of that bumper at the farthest point. It's like 3" at most points. It sits 3 1/4 inches from the ground and rubs under braking with 500 lb front coil over springs.

My rear wing is 62" wide well within the rules. It is 1 1/2 farther back than the bumper cover. Again within rules. It's also aluminum.

Front splitter cost. Under $300.

Dive planes (also aluminum)$140 I know this after having to replace one from Nationals one of the three hits I took.....

Rear wing $650

 

No doubt people can spend the world on aero. I haven't. I haven't even tested the new splitter thoroughly.

There are lots of places people CAN spend money on in other areas that would do more at this time in my opinion. I do think there needs to be some kind of rules regarding aero but time needs to be spent planning enforcement first. I'd be happy to discuss my car in length if it helps this discussion.

 

On and TJ, my Stoptech brakes only cost me $1200.

[ST#97]

Splitter -

Min 2" ground clearance

Can not extend rearward beyond the center of the front wheel

Can not protrude more then 3" from stock location of front bumper cover

Must not be wider then the track width of car. Also, no pieces wider then the track width, ie, canards, splitters, etc..

 

Underside of car

No aero compontents from the mid point of the front wheels back. ie, flat panels, diffusers, canards (sp), etc....

 

Wings

Current rules

 

Front bumper covers

Must appear stock looking from the middle of the bumper upward. Modifications below the mid point of the bumper cover are ok, as long as they meet all other rules.

 

Have at it !

 

2000R nose has the lower splitter 5" beyond the face of the vertical bumper...and on New Edge cars, the stock fenders and 2000R nose can easily cover and extend past the current 73" track width. Only issues I have with what you posted...again, just facts from my current setup. If someone were running the tiger racing nose, they would not be legal. Also, I think Canards should be allowed...as long as someone can tell me where to buy them!

[Red Tornado]

I would be hard pressed to think any aero rule would make a stock cobra r splitter illegal.

 

I think the aero rules have worked fine so far. Honestly I think folks are missing the real play at Miller. You want a good drag coef here and some big hp (even with the weight penalty) to get some serious speed down the straight.

[King Matt]

Speaking of that, if the aero rules are going to be cleaned up, it might be a good time to clarify to subject of adjustable wings. All the rule says is "spoilers and airdams ... must be fixed for competition." Maybe that means a cockpit adjustable wing is legal?

[D Algozine]

I had a feeling my specific dimensions would be attacked. But, generally speaking, I think some type of parameters should be laid out.

Just to clarify, I'm not advocating a show room stock class, but I think it would be a good idea to set some guidelines, regarding aero and panel modifications.

[ST#97]

I had a feeling my specific dimensions would be attacked. But, generally speaking, I think some type of parameters should be laid out.

Just to clarify, I'm not advocating a show room stock class, but I think it would be a good idea to set some guidelines, regarding aero and panel modifications.

 

Agreed! Just giving facts for reference!

[D Algozine]

I had a feeling my specific dimensions would be attacked. But, generally speaking, I think some type of parameters should be laid out.

Just to clarify, I'm not advocating a show room stock class, but I think it would be a good idea to set some guidelines, regarding aero and panel modifications.

 

Agreed! Just giving facts for reference!

 

No worries.

I just picked dimensions from previous posts that I thought sounded good. I don't claim to know what the parameters should be, just that I think there should be some. Currenlty the way I read it, you could do just about anything to the front of a car. I think cars should resemble their orginal "look".

Same thing goes for the fenders.

Can they be pulled out? If so, how?

Can they have vents and/or holes? If so, what details?

[horsewidower]

I think the rule should begin and end with "no aerodynamic devices from axle centerline to axle centerline"

 

The horse is out of the barn on the fenders, hoods, bumper covers, minimum height, etc.

 

And I agree with Matt, under the current rules you could have a cockpit adjustable wing.

[Red Tornado]

Has the aero thing been an issue really???

 

I hear what folks are saying but I think power to weight limits you and I would love to get advanced thinking going on the aero as I think that would be an edge.

 

In my mind until someone beats everyone by several seconds at nationals running one of these "sweet dream setups" it's all a worthless discussion.

 

I am sure someone could massively improve on my aero setup but more power to them for $5k plus more money and a tenth or two.

[swhiteh3]

In my mind until someone beats everyone by several seconds at nationals running one of these "sweet dream setups" it's all a worthless discussion.

So our approach to rule making should be... "wait until someone does it successfully, then send them home?"

 

When there were no AI cars, and the AI rulebook was first being worked on, maybe we should have had no rules, since no one had proved that anything needed to be outlawed?

 

Creating a rulebook which sets a level playing field BEFOREHAND is the only fair way to do it. Creating rules after-the-fact when someone has success is just an example of discriminatory rulemaking. As we wait longer and longer, we risk pissing off more and more people because they've already violated the rule.

[King Matt]

Again, I bring up the Can-Am example. Red's approach is a great way to kill a series. There are two inevitable outcomes: 1) The team that perfects the "Unfair Advantage" will drive everyone else out and the series will eventually die from lack of participation, or 2) You penalize success and force out those who develop advantages. That may not kill the series, but it will certainly stunt its growth and leave a lot of unhappy people in its wake.

 

Or you can be proactive and avoid either of the above outcomes by establishing some limits beforehand.