Black Ops for the '04 Open Track Challenge
 

Well, we don't need to be too sneaky, since none of the M3s dared to show up this year. We're pretty much assured of a first place finish in our class, even without any clever tricks.

But the TRE Motorsports team of Jack Olsen and Tyson Schmidt is testing out a new idea of Tyson's this year, which is to improve the aerodynamics of the part of the car not covered in smooth paint.

http://forums.pelicanparts.com/uploa...1082049814.jpg

It's an 8-foot-long sheet of .90-mil ABS (technically: Acrylonitrile Butadiene Styrene, I learned from the salesgal at the plastics warehouse), and it runs from the back of the front condenser all the way to the rear swaybar. It undoes some of the aerodynamic damage done by the pre-964 underbelly design, and -- in my particular case -- the big AC condenser I keep down there.

Weather forecasts call for 70-degree highs for most of the week, so sacrificing some AC functionality is a minor concern. And in a pinch, the thing unscrews and rolls up for storage.

You have A/C in that thing? I never knew that. What a panzy! ;)

That's a cool trick. Let's see how it helps.

Looks good but I would think a screw at each corner by the front torsion bar covers might be some added insurance to make sure those corners don't catch air and bend down at high speeds.

BB2 has A/C, a cup holder, and 9 second delay dome lights. It's a true pimpmobile. :cool:

Don't forget the full leather interior. ;)

Look very clean and should smooth out some of the turbulence under there.

I have a question, where the ABS ends, it seems as though something is dropping down below the sheet, is that just the bottom of the motor or an optical illusion caused by the exhaust or rear bumper???

Re: Black Ops for the '04 Open Track Challenge
 

Wow - I hope you knocked on wood about a hundred times as you wrote this. Talk about tempting fate -



Bill

Every time I think I have a really cool car, Jack posts something to put me back in my place.

I like it!

Any worry about high tranny temps? Can't see back that far but it looks like you may be far enough back to block air from circulating around it and letting the cooling fins do their work. Maybe you have a tranny cooler somewhere and I'm barking up the wrong tree or the plastic doesn't reach as far back as it looks.

I commend you on your creativity and thinking outside the box.

You should shave those tires too. I bet all those tread blocks create a ton of drag ;)

Good luck out there!

Jack, what is going to happen when you are at speed and air gets trapped between the floor and the abs? I would think that there would be enough force to rip the sheet away from the fastners. Imagine this flapping abs getting caught up in the frear wheels while in a turn no less. Just a thought for safety. Best, Aaron

Hmm, lots of valid points, I wonder how this is going to work out.

I've wondered about trying to smooth out the bottom of the car myself, some of the tricks that I have heard of (primarily from either Porsche or Ruf) is 1) a lip spoiler in front of the engine area (Ruf CTR), 2) deflectors in front of each rear tire (used, I think, on stock GT2's), and 3) an underbody tray kind of like Jacks, but I was thinking thin Al, not ABS and possibly something near the engine (ala 964, CGT, several other cars Porsche and not).

Too, what about a deeper rubber front lip like you see on so many track cars?

Maybe, f/g or carbon fiber sheet epoxied to 1/8 inch alluminum flat bar for reinforcement.

Is it a safe assumption that this will help the overall aerodynamic package? Agreed that well designed cars have flat bottoms. Is it a stand alone improvement or does it require/allow for additional changes to other areas (wings, splitters, overall top side profile) to get necessary benefits while keeping the chassis dynamics as you expect (mechanical grip)?

I guess I am thinkng along the lines of the front lip and the rear wing. Front lip is okay alone. Rear wing is okay with front lip. Rear wing alone is BAD. Could this have a similar effect?

Still worth testing for sure.....

Jack, do you use street tires or DOT approved ones? Hoosiers?

Actually, I think, yes just smoothing out the bottom of the car (or side, or top, etc...) will improve aerodynamics. I guess just the right kind of non-smooth surface would be better (think golf ball), but I don't think the bottom of our cars is that surface.

That will make the car more slippery, it may or may not reduce lift, but at higher speeds it should be a good thing.

well it WILL make the airflow smoother, therefore faster, under the car... the quicker the air from under the car exits, the more efficient the "push" from above (downforce) becomes

Nice Work Tyson.
 

One thing that might be of minor concern is if it increases the amount of air "spilling" out the sides. You might try experimenting with side skirts (rocker extensions) and/or vanes.


This reminds me of a spiffy front under-tray I saw on an ebay car recently:

http://forums.pelicanparts.com/uploa...1082059728.jpg

what are the two naca ducts for?? Cooling the steering rack?

Look under a 964 and you'll get the idea! Next TRE/jlmpro product is a true one piece bolt on bottom with venturis to induce downforce. See it here in 90 days! Be the first on your block with a smooth bottom! The'll market it as the concrete terminator for Nostatic.

I know the f1 cars used to have enough downforce with their wings/underbelly to be able to run inverted at 100 mph.

cooling and/or suction?

Eric, the front bumper and splitter are not lower than the belly pan anyway, so there is nothing to try to keep from spilling. If we ran a deep front airdam, then that would definitely be a consideration.

The picture is an opticalk illusion, and the sheet ends right at the rear swaybar, so no blockage of the trans is going on. Jack has a trans cooler anyway.

Amir, the bellypan is quite a bit lower than the engine. It's the funny angle of the picture that makes it look like the engine is hanging low. It actually looks way better on the hoist in person. Looks very F1!

We'll have to do some back to back runs at Willow to see how effective it is at reducing drag.

BTW, if it does alter the downforce distribution, the rear wing angle can be adjusted to compensate.

I would echo the worries about picking up air in the front gap (right behind the condenser). I think you need to seal that front edge off, or have something extending from right behind the bumper then overlapping that front edge so it isn't exposed.

I wonder if we can pull your car into the wind tunnel at Caltech...

Hopefully shaped so not to collect fluids in the center

Yes, all you armchair engineers. We know about the gap, and we had tabs built in so we could strap it up to the body, but they tore.

Our next plan is to install block offs.

I can't wait to hear the results!! (it's just too bad Jack couldn't write himself out of a wet paper bag... ;) )

We should have known that Tyson would have all of the bases covered.

You should run a diffuser tray in the rear also. Look at all the Vipers, Vettes, etc.

Oh man, would I LOVE to be able to do that! But with a rear engined car, it's just not feasible. Porsche did their best with the 964 and 993, but there just isn't enough room for it. You'd have to raise the engine up in the car.

Dont disappoint this entire board,.... Make it happen,.. :)

Im sure a 1 or 2 inch vane would work.

Yes, the angle of the picture is pretty misleading. The engine is higher than the cover. The front condenser is lower. If you see it in person, you'd see that there is really no way air is going to get between the plastic and the car in front.

The sides, right behind the wheels, are another story. I'm working on a block-off for that -- although the wheels and brake cooling diverters all push air away from the opening. I suspect if we left it open, it would be fine. (But we won't.)

For this event, we need to run street tires with a wear rating of 140 or higher. That means no R-compound anything. Ordinary BFGoodriches. We shaved them last year, but didn't this year, since the competition won't be as close. ;)

Wouldn't a dimpled surface work better than a smooth surface (similar to the Lexus commercial)?

I think I'd add a smallish rubber lip at the back like the CTR's to reduce the turbulence around the engine, and maybe try to seal the front with some RTV to avoid it tearing off. I wouldn't be concerned about the extra drag if it did start to come off, but the black flag time could put you at a real disadvantge.

Black flags do not scare us.

http://forums.pelicanparts.com/uploa...1082071721.jpg

Boldly, I predict a first in class in this year's Open Track Challenge.

(Of course, as of this writing, we're the only entry in our class. :rolleyes: )

Jack Olsen, you're just too d@mn cool, buddy!!

I wanna be just like you when I grow up! :)

Unfortunately, the prospect of me ever growing up doesn't look good at this point, so I may just have to endure BB2 envy and leave it at that. ;)

Oh, do you play an instrument, paint and sculpt too? Writing, photography, driving, what artistic endeavor aren't you good at?? (besides not ending sentences with prepositions)

O.K., I nominate you to come over and install a thousand thumbtacks into the bottom of the undertray. ;)

having limited knowledge in this area wouldn't it be better to move the air around the outside of the car rather than smooth the air under the car? i would think that it would create more lift at higher speeds.

like an air plane wing the air splits at the front and that air that goes under is fast and dense. the air the goes over has to go faster and is streched out (thin less dense) the differential pressure creates lift. spoilers just disrupt the lift by spoiling the air flow.

more turbulence on the bottom would spoil lift wouldn't it?

good luck on the challenge......looking forward to a good read on the events Jack.

Actually, Tyson's the cool one. :cool:

I smell a Titlest sponsorship...

Yes and no. With a big, low front end, you move the air out of the way in advance -- but you also increase your frontal area, significantly. With twice the horsepower, this wouldn't matter so much.

But more essentially: I tend to go spinning off the track a lot, and low, aerodynamic front ends tend to get sheared off.

A past experiment:

http://forums.pelicanparts.com/uploa...lowOct25-M.jpg

And after:

http://forums.pelicanparts.com/uploads/44Remnants-M.jpg

I think you're missing the point. We're going after faster lap times by reducing the overall drag. Downforce isn't the limiting factor with Jack's car, since we can go flat-out through most high-speed sweepers.

With the wings and flares, Jack's car is burdened by lots of drag, which is costing us a lot of pulling power down long straights. The Viper and 'Vette guys spank us down the straights, even though we kill them in the corners. Just trying to get some of the top-end speed back.