Daytona aerodynamics question

[Lifsgrt]

 I'm building a streetable Daytona-style racecar for a high-speed run at the Maxon Mile and Bonneville.  I've done some research, but does anyone know of a good source of info on the effects of removing the side rain gutters, etc?  I've studied the WW/NBOA website, there is a lot of info there.  Thanks

[FJMG]

    Make some models and make friends with some engineering students at a university with a windtunnel.

[triple_green]

You have friends here 

One of my job's in the past was managing (Business not technical) the Boeing Co's Wind Tunnels. I emailed our Philly tunnel manager and here is his response:

"I'm not the expert on this topic but it's hard to believe that the gutters will have a significant impact on the overall speed of the car.  I would think tire pressure would have a bigger effect.  Removing the rain gutters might also weaken the roof line.  The gutters must add some significant stiffening.  The guys that run the Lockheed low speed wind tunnel are pretty smart about all of this.  They've test a lot of cars in their wind tunnel. .

Merry Christmas!

Bill"

Hope this helps! Note: LMCO not IMCO (Lockheed Martin Co.)

Mark

[0X01B8]

You oughta remove Marks e-mail address from the post and PM it instead.  Otherwise he's gonna get a torrent of spam.   

[Redbird]

There was a really good article on aerodynamics in Hot Rod a couple of months ago. If you want to go cheap fast buy a '82 Firebird. If you have money to burn then build a wing car: too tall, too wide, too big. Stand next to a '82 Firebird that is slammed to the ground and see how tall it is, plus a great back window.

[Daytona Craig]

I am building a clone of the K@K #71 as it ran at Bonneville in 1971. I am removing the gutter as they did on the #71. As a Aerospace Engineer I think it could help pick-up only a couple of miles per hour, but it looks cool! They did a lot of other little things to the "Bonneville Car" that look a lot of work, such as removing door seams, bondowing up window seams, removing rain gutters, removing the external supports of the rear window,smoothing out the front window pillars, it does all add up.They probably picked up 5 mph with the mods. I don't know why they didn't cover the wheels with moon discs, that would had made a far greater aerodynamic improvement on the vehicle, I figure it must have been the stock car rule for the record run.

[daytonalo]

Let see some pics !!!!!

[Redbird]

Read Hot Rod March 2007. I watched Larry Lindsley go 217 in his Superbird in 1981. He went 333 in his Firebird a couple of years ago. The Firebird did have a Les Leggett engine. The only way the Superbird would have gone 333 is if it would have been dropped from a plane. My Superbird went 198 at Bonneville. I believe it was the fastest a normally aspirated Max-Wedge has ever gone. If you need 5 mph you take off the front brakes. Duct taping the body seams, well I tried that, only did that once. Gary Eaker, who has the wind tunnel in the Hot Rod article, pitted next to us one year. He went so fast in his Firebird too.

[Highbanked Hauler]

There was a really good article on aerodynamics in Hot Rod a couple of months ago. If you want to go cheap fast buy a '82 Firebird. If you have money to burn then build a wing car: too tall, too wide, too big. Stand next to a '82 Firebird that is slammed to the ground and see how tall it is, plus a great back window.

   The roof on a Firebird probably isn't much higher than the top of the door on  a Charger

[Mike DC]

Firebirds & Daytonas are apples & oranges. 


And "Aerodynamics" is a pretty broad category. 
Drag resistance?  Downforce/vacuum?  Directional stability?   Those are 3 totally different things to study about a car's shape.



The Firebird probably kicks the crap out of the Daytona in terms of the net amount of drag resistance.  The Firebird gets the nod at Bonneville, no question. 

But a Daytona's vertical wing supports have more directional stability than a Firebird could ever dream of.  The Daytona's shape would kick the crap out of the Firebird if we're talking about being crossed-up at 190 mph on a NASCAR track.     

   

[learical1]

Firebirds & Daytonas are apples & oranges. 


And "Aerodynamics" is a pretty broad category. 
Drag resistance?  Downforce/vacuum?  Directional stability?   Those are 3 totally different things to study about a car's shape.



The Firebird probably kicks the crap out of the Daytona in terms of the net amount of drag resistance.  The Firebird gets the nod at Bonneville, no question. 

But a Daytona's vertical wing supports have more directional stability than a Firebird could ever dream of.  The Daytona's shape would kick the crap out of the Firebird if we're talking about being crossed-up at 190 mph on a NASCAR track.     

   

Remember, it's the co-efficient of drag multiplied by the frontal area.  Both the winged cars and the Firebird have low c/d, but the Firebird is smaller, with a lower frontal area. 

Storytime: My brother and I were returning to Phoenix from Los Angeles after a photo shoot (the courtyard pictures of the 500, etc.)  We were driving our Tor-Red SuperBird, the one that Redbird owns now and took to Bonneville.  We were cruising eastbound around 10 PM along a heavily tree-lined section of I-10.  We're moving at a decent clip (National speed limit at this time was still 55MPH, we were doing about 70) when I see a VW bug up ahead.  The guy was obviously drunk, weaving all over the road, unable to stay in one lane.  I cranked the speed down, trying to figure out how I'm going to get around this with jerk.  All of a sudden, we came up to a break in the trees, I saw we had a cross wind of about 50 MPH blowing.  I couldn't see the wind blowing, I couldn't even feel the wind affecting the 'Bird as I drove, but that poor VW was being pushed all over the road.  THAT'S what the wing's vertical supports do!