Belly pans for aerodynamics

[Guest needwaymorespeed]

Race car engineering?? do they have a web site ? do you have a phone number for them

Thanks

[Drax240z]

Oh yeah, now everyone found my secret. (racecar engineering) Its a great magazine.

[randy 77zt]

i have been getting race car engineering at local book store.lots of really cool stuff but mostly good high tech reading.i did download a sample efi program from a company called datafast that is really easy to use -i might email them about efi system.about going 200 mph-i know a place where there is 30 miles of open dry lake-land is federal blm.no permit needed.i hit 90 mph on my dirt bike out there.

[johnc]

Racecar Egineering's editorial office is at:

 

Focus Network

Racecar Engineering

Dingwall Ave.

Croydon CR9 2YA England

+44 020.8774.0600

 

I buy the magazine off the newsrack at Barnes and Noble ($7.95). I used to have a subscription, but when RE moved to their new offices I stopped getting it.

 

Another good resource is Race Tech. They publish 6 times a year. Again, I get it off the newsstand but both magazines are distributed by:

 

Eric Waiter Associates (EWA)

205 US Hwy 22

Green Brook, NJ 08812

732.424.7811

 

You can probably contact EWA and get a subscription going.

 

Race Tech is happy to publish well written and photographed car engineering/design stories from regular racers like us. Their editorial office is at:

 

Race Tech

841 High Road

Finchley

London N12 8PT England

+44 020.8446.2100

 

FYI... Both recent magazines have a great discussion about Ackerman steering.

 

[ June 20, 2001: Message edited by: johnc ]

[pparaska]

I found Eric Waiter Assoc. book page at: http://ewa1.com/cgi-bin/webcartb/webcart-frames.cgi

 

Racecar Engineering US 1st class /yr is $116.00

 

US 2nd class is $79 /yr

 

Ouch

[Drax240z]

I had to scan one article out of racecar engineering for my FSAE team, so since i had it scanned I figured I'd put it up for you guys to take a gander at, so you can decide if its your 'cup of tea' or not. 5 pages.

 

http://members.home.net/drax77/Ackermann1.jpg http://members.home.net/drax77/Ackermann2.jpg http://members.home.net/drax77/Ackermann3.jpg

http://members.home.net/drax77/Ackermann4.jpg http://members.home.net/drax77/Ackermann5.jpg

 

[ June 20, 2001: Message edited by: Drax240z ]

[randy 77zt]

good belly pan material is aluminum road signs-light and tough.have used them to make skid plates for dirt bikes.

[DavyZ]

Great idea--only getting one legally may be a problem...

 

David

[Guest MM_280Z]

Frank Rich: Thanks for posting that! That's exactly why hearing of a 200 MPH Z attempt with bellypan made be so nervous.

 

The Z has such a nice airfoil shape on top that allowing a laminar airflow below it will cause... liftoff!

 

What you need to do is "spoil" the laminar (smooth) airflow over the top of the car.

 

As long as we are trading crazy ideas, here is mine:

 

Cut 2 holes in the floorpan on either side of a trans, around the shifter position. Cut a slot 1.5 inches wide in the hatch around the top of the glass position, traversing the car.

 

Now, create a piece of ducting of carbon fiber or aluminum. Place 2 LARGE ducts/scoops under the car. Run the ducting from the scoops on the floor to the slot in the hatch! Join the ducting from the scoops in a Y-joint fashion round about elbow level in the ****pit, and make a smooth transition to the flat portion of the duct going to the center of the car. You'd need some baffles of diverters in this area to get the exiting airflow even across the width of the car. (otherwise it would mostly exit the center)

 

This way, you have solved your problem on several levels:

1. You have disrupted the laminar airflow below the car (Venturi effects)

2. You have disrupted the laminar airflow ABOVE the car (spoiled lift)

3. With the slanted ductwork, you have created an in-car wing smack dab in the middle of the car, which also tends to keep the car on the ground.

 

If you wanted to get really insane, you could place a large powered turbine-like fan in the ducting to FORCE air through, enhancing the effect.

[Guest Anonymous]

does anyone know of a web site for the people who run at bonneville each year? some one must have tried to run Z faster than mr K ever planned on and solved some of these problems.

[Guest Frank Rich]

That's a good point Kirk - does "TonyD" (all I remember is his "handle" from zcar.com posts) ever hit this site? He's been involved in some LSR attempts at Bonnevile with a Z-car running in the appropriate class, and I bet he would have some great input on this subject. Does anyone know the guy I'm talking about?

 

"Lead me not into Temptation, I'm getting there just fine on my own"

 

Frank

[Mikelly]

Well if someone else has already overcome these hurdles, I'm all ears. I'm NOT for re-creating the wheel when at all possible. I only know of one 1st generation Zcar that has reached speeds in excess of 180 miles per hour. That was the vehicle discussed in the two installments of the ZCAR mag article.

 

One thing I was looking at was possibly using air ducts to plumb air into the trans tunnel, and out the back of the car, using the air to cool the trans and the rear diff... I saw this in a race tech article I have from Grass Roots Motorsports, and have another blirb on this type of design from a "SALT FLATS" news letter (Or something like that sent out to subscribers and members of the timing association). It is very interesting reading, as has been this thread... Maybe the software simulation is the best idea based on Michael's, and other comments here...

Mike

[Guest needwaymorespeed]

Mike what year and months is that car featured in the z car mag,I would very much like to read about it.Hopefully eric will have it available as a backissue

Thanks

[Mikelly]

Curtis,

Do a search here on this topic and you will find the issues that Zcar printed these specific stories on one mans quest to break 185MPH. The car was a black 76Z (I think...) with side skirts, a Gnose, and a turbo.

 

Mike

[johnc]

Frank,

 

I don't want to sound like an *******, but as I've posted before in this thread:

 

> And the recent discussion about the

> Advantage CFD software in the June issue

> of Racecar Engineering confirms that,

> without a rolling ground plane, wind

> tunnels are inaccurate by some significant

> numbers when testing underbody aero.

 

Your wind tunnel idea would be great for overbody testing but when you start working under the car, the road, spinning tires, suspension movement, ride height changes, et. al. are very significant contributor's to your ultimate results.

 

Everyone,

 

At 200 mph you are taking a big risk relying on bent up street signs and yarn tuft testing. Aerodynamics are the big issue, but there are a lot of other things you have to check:

 

1. What happens to the rear hatch, door, hood, rear 1/4 windows, cowl finisher, fuel door, and inspection panels at speed?

2. Can a stock windshield and gasket handle that air pressure without blowing out?

3. Can the wheel bearings, spindles, stub axles, differential, halfshafts, brake drums, rotors, wheel studs, etc. handle the rpms they will be experiencing at 200 mph?

4. What happens to the car if a side window blows out at speed?

 

If you are going to do this, work up to that speed slowly over a period of a few weeks. Kinda like what the Thrust SSC team did on their quest to break the sound barrier.

 

Going 200 mph in a Z is a similar accomplishment.

[Guest Frank Rich]

JohnC, I don't think you're being an ******* at all, and I completely agree with what you're saying - now, if you'll look at my previous post again, you'll see that all I plan to use my low-tech, low-speed setup for is a baseline for general conformations (and by the way - yarn-tuft testing is still used not only by a lot of experienced homebuilt aircraft designers/builders, but also by a lot of automotive racing teams in wind tunnel testing because the direction(s) in which a yarn tuft points or moves in an airflow can tell you a lot about several characteristics of that airflow. If you cover the surfaces of a body shell, or fuselage or underbelly pan or whatever with several hundred 80mm tufts of yarn attached with high-tack tape dots in evenly spaced rows, then videotape the patterns that they form and the motions which they exhibit under exposure to various velocities of air flow, you can learn a lot about what that airflow is doing as it moves across the surface(s) in question).

 

I also think that a carbon fibre/kevlar composite is the way to go with this project, not used aluminum signage (just kidding - not taking shots at anyone...), and I fully realize the need for testing over a moving (rolling) ground plane that changes contours and causes the accompanying changes in suspension configuration frontal area, ground effect air cushion density, etc.. The variables involved here are numerous and all have a significant impact on the final results. If you go back to my earlier post again, you'll see that I talked about incremental advances - not hopping in a car and trying to go all-out based on partial data. (And incidentally, having talked to a friend who designs boat hulls for a living, I have severe doubts about relying too heavily on fluidic dynamics data to solve an aerodynamic problem - apparently very different compression factors, boundary layer characteristics, and a host of other variables make this an area where much caution should be exercised before assuming that a fluid stream moving at a given velocity will exhibit the same characteristics or exert the same forces as an airflow stream moving at that same velocity. For what its worth.

 

I would also expect that all mechanical components on a car aimed at 200 mph would be upgraded to the point of extreme reliability by anyone with enough sense to really understand what it takes to go that fast - a category that I'm sure Mikelly and several others on this forum fall well within.

 

I do understand your concerns - they are all valid - but I also think there is room for exploration here without crossing the line into foolhardiness or the need for NASA-like budgets. Besides, this gives me a great chance to use the new fiber optic "lipstick" cam that I just paid SONY waaay too much for! Little devil ought to tuck into just about any place I care to put it...Hmmm - that may be a whole different thread...

 

"lead me not into Temptation, I'm getting there just fine on my own"

 

Frank

[Guest Frank Rich]

Okay, I know that this is probably going to draw comments like "...cardboard wind tunnel" again, but here goes!

 

I think that one of the most important things to remember in this effort is that even the best - and I do mean the VERY best - computer simulations are just that - simulations. I have the utmost respect for hard-achieved, sophisticated data that is the result of hundreds of man-hours of code writing and programming, BUT (you knew that was coming didn't you ) even at NASA they lose a certain percentage of their prototypes during flight test because there are real world variables and unforseen conditions (or combinations thereof) that can only be encountered and hopefully addressed by the process of full scale, real time, physical prototype testing. The best CAD/CAM software in the world is nothing more or less than an extremely sophisticated tool to get a designer most of the way to the finished product. I think that you can gather a lot of very accurate, very useful data from any number of good software packages and custom programs, but the real determining factor for achieving high speed with reasonable safety(and that's all any rational person can expect at 200 mph - a reasonable amount of safety, because when you push the envelope that far, there are absolutely no guarantees, as I'm sure Mikelly is well aware)is going to be observing and recording the way a full size, running and completely functional prototype reacts to all the myriad inputs that will occur on the way to the target speed. And let's face it, we are all building prototypes here - no two of us have exactly the same cars, built in exactly the same way with exactly the same equipment, no matter how much good information we share!

 

Now, I've gotten pretty interested in this aerodynamic belly pan concept, and I got back in touch with my former sailing colleagues. The "cardboard wind tunnel" (40' x 72') about an hour outside Houston is still there, and Jack said that I could use it to test underbody panel designs on days when they're not testing sails if I'd just "clean up" after my self. (meaning any test stands, extra equipment and support crew are my responsibility - and don't break it or you buy it!!) Now this facility will "only" generate airflow speeds up to 83 mph (measured by digital anemometer)for testing storm sails in minimal hurricane conditions, but that should give me some baseline airflow conformations to videotape, and by using the tried-and-true yarn tufts and colored smoke technique, I can spot areas of boundary layer separation, loss of laminar flow, vortex turbulence, and all the other little gremlins just waiting out there to screw up my day! I may even be able to "tweak" the three 6' fans up to a higher max velocity - but my friends don't seem too keen on that idea ! Is this a crude setup compared to a major university or government facility? Abso-f*cking-lutely! Does it give me a real world starting point that I can expand upon with careful, incremental increases under controlled conditions on a track, videotaping from different vantage points all the while (I just love those big rubber suction cup mounts for the camera arm - they stick so hard that you can deform the sheet metal if you're not careful!!)? What do you think? Now where the heck did I lay down my Gtech???

 

"Lead me not into Temptation, I'm getting there just fine on my own"

 

Frank

[Mike kZ]

Mikelly, I was reading an old Hot Rod mag and came across an article on the ECTA (East Coast Timing Association).Not sure if you know this but there is a 10,000 ft deserted concrete runway from WWII in Maxton North Carolina, not to far from you. membership is $50/year, and $100/car entry fee. Most cars are running 180+, this would be a good place to test your car out. For more info call John Beckett at 828/684-3009

[Guest Anonymous]

There is more aerodynamics data on line than can be absorbed before your z returns to the soil. however, I found a great site to start. www.nas.nasa.gov/about/education/racecar/

After going into data I'm ill prepared to comprehend, it seems to me that a full bellypan would require to much engineering to avoid going ballistic. the good news is a minor cleanup of obvious areas of belly drag

combined with a very agressive front spoiler

should enable your z to pass the magic number. Damn, I make that seem easy. there are so many problems and varibles at 200mph that I feel like I need a legal disclaimer for urging you to do this. speed is so addictive. good luck.

[Guest Anonymous]

Whaaa?? I've been to the laurinburg / maxton airport before, I think I know the runway you speak of.. we were doing an autocross there..

 

Meaning, Mike Kelly isn't too far away from me?!?!?! Mike, I live in Sanford (a little bit north of Fayetteville), and work in Durham.. Where are you??