Air Extractors - it's a done deal for me - listen to this

[Daytona Guy]

This Hell-Cat intro explains it all (7:14) - just place yourself 44 years earlier and have a Daytona sitting there - and it is a done deal for me. It's all about air control.  There is NO WAY in this test mule they had tire clearance in view using these air extractors.

https://www.youtube.com/watch?v=xZ66boFL5Qs

Dane

[Indygenerallee]

Yep same thing I have always thought, gotta let that air out of the engine bay or you might as well be pulling a open parachute behind the car.

[Mike DC]

 
I think history suggests that it was both issues.  Tire clearance started the idea and then later air extraction finished it.  


They were having tire clearance problems on the 1968 "2+2" cars which were pretty far lowered in front.  That started the idea of putting something on top of the fenders.  Then NASCAR banned the severely lowered bodies.  But the air-extracting benefit of the scoops had been proven by testing in the meantime, so the scoops stayed on.


IMO it's pretty clear that the engineers always had air-extraction in mind for those scoops.  If not, the scoops would have been just "lumps" without the open hole in back.  The only reason to have the bulges over the wheels end in a reverse-facing open scoop is to let air out.  It's an aero disadvantage compared to a smooth lump if there is no air-extraction going on.  And aside from some clay mockup shots, I have never seen any early pics of 1:1 scale cars on the track with smooth lumps over the fenders - they were always carried out as open holes.  

[Daytona Guy]

I can't see how it could logically start with the a tire issue when the test mule (when they started testing) clearly did not have that in mind. Even the shape is a classic aerodynamic outlet (inlet). It really can't get any clearer for me. If it was a tire issue - then use a hammer like the way they solved all the other sheet metal issues

We have 4 factual evidences for airflow -
1. Historical documentation stating a gain in aero
2. Their historical name "extractors"
3. The test mule shape - is an aerodynamic air outlet - (that does not allow for tire clearance).  
3. Present day functionality of the location and factual benefits of air extraction.

[Ghoste]

I think its air too.

[TUFCAT]

Hence the name "air extractors" - versus some other name like, oh I don't know..... "tire clearance cutout bump cover thingies"  

[odcics2]

"Exhausters"  =   3% drag reduction.   

That's what it says on the John Pointer authored vintage documentation. 

[rnjump]

 

[C5X DAYTONA]

Dane,  Your looking into the future.      Think as if you are in late 1968..   There is something missing in the original drawing..  Extractors....     Odd thing is the 3/8 scale wind tunnel car has never been fitted with "Exhausters."  There is NO paperwork to my knowledge that shows a E-Series test date or test number for the extractors.   

[C5X DAYTONA]

"Exhausters"  =   3% drag reduction.   

That's what it says on the John Pointer authored vintage documentation. 

Greg,   When was that tested?        Gary Romberg and George Wallace both are very adamant that was not the case.
   

Gary talks about it on the Aero Warriors page.
http://aerowarriors.com/aw99.html      Audio only..   Bottom of page on left side.
Gary discusses the fender scoops found on the Daytona and SuperBird. (85 sec. - 1.36MB   

I could not figure out a way to post the audio video for some to hear but the audio is posted on that page.  I know you have heard it.

[C5X DAYTONA]

This was the car ALL wind tunnel testing was to be done on.   My father had this very 3/8 scale car in our garage for years.   There has never ever been any holes drilled into it over the tires for anything.    Remember this car also had an electric motor with a fan to simulate air being sucked into the grill...  But no extractors..

[C5X DAYTONA]

This is EXACTLY what George Wallace told me in 2004 on our way to Talladega.  Off subject a tad but good read about how they came to be on the street version..    Below is a quote from the Aero Warriors site:   

On a related subject, winged car guru Dave Patik recently confirmed that he had asked Chrysler engineers in the late 1970's why street Daytonas had holes cut in the fenders, while SuperBirds did not. Dave was told that Chrysler wasn't confident enough about how NASCAR might interpret its own rules when it came to racing Daytonas' scoop holes, and thus holes appeared on street Daytonas as a strict interpretation of the Homologation Rule would demand. Once Daytonas had made several race appearances during the 1969 race season, Chrysler apparently got a feel for the degree of latitude NASCAR would allow in its rules interpretation for the winged cars, and the decision was made not to cut the street SuperBird fenders. This saved time and expense on a program that was short on time and long on expense. And of course Chrysler's call on this was correct, as all NASCAR racing SuperBirds were allowed to compete with holes cut in the fenders under the scoops. Interestingly, Chrysler Technical Service Bulletin No. 70-23-6, dated January 6, 1970, instructed dealers on how to put holes under the street SuperBird scoops if the buyer requested it. Perhaps this bulletin was an attempt on Chrysler's part to hedge its bets a bit, in case NASCAR got a little more stringent with its rules for the 1970 season. With the bulletin having been published before SuperBirds were even officially deemed eligible for NASCAR competition (this happened January 14, 1970), it may have served to bolster whatever arguments Chrysler might have presented on why the racing SuperBirds should sport fender holes even though the street cars did not.

[C5X DAYTONA]

More from the Aero Warriors site:

Chrysler Perpetuates The Tire Clearance Explanation
          The seed of Chrysler's tire clearance explanation was planted in the automotive press in the late 1960's and it has born a great deal of fruit. If any article about the winged cars from the last 30 years is reviewed and the scoops are discussed, it will almost certainly mirror the Chrysler tire clearance scenario. As part of the research for this article, it took the author less than one hour to locate the following excerpts from several different automotive sources:
•   Winged Warrior Newsletter, August, 1976:
          "...the scoops on the front fenders are not to let air out, but to allow clearance for the tires on a race car! Gary [Romberg] said that the scoops alone baffled the competition for a long time as to just exactly what they were for."
•   Winged Warrior Newsletter, August, 1977:
          "Probably the main question asked of John [Pointer] in the question and answer session again this year was what the purpose of the fender scoops [was]? John said it was found in the Charger 500 that in super speedway cornering the right front tire was rubbing up against the fender causing the terrible smelling smoke to enter the driver's compartment making it unpleasant to drive. So to get the extra one inch of tire clearance they needed for the right front tire they put the scoops on the car, and for no other reason."
•   Winged Warrior/B-Body Review, September, 1996: (question to John Pointer)
          "(Q) OK, if the Daytona racecar's fender scoop is for clearance, why doesn't the fender look as wide as the tire?

          (A) Tires are not straight up and down when turning. It was only the top outer edge of the turning tilted tire that rubbed so the scoop was enough to let it clear."
•   Supercars: The Story of the Dodge Charger Daytona and Plymouth SuperBird, by Frank Moriarty:
          "Curiously, one aspect of the press preview seemed to cause endless fascination and speculation among the witnesses. Why did the wing car have rearward facing scoops on the fenders above the front wheels? To this day, articles and books about that era still come up with a bizarre array of explanations for the scoops, ranging from alleged aerodynamic benefits to engine heat ventilation. In reality, the purpose of the scoops is considerably less exotic.
          At the NASCAR super speedways, front tire clearance in the wheel well was often a problem. The tires would be forced into contact with the fenders when the car passed through a high-banked turn at nearly 200 MPH. To solve that problem on the Daytona, Larry Rathgeb came up with an idea -- a backwards facing air scoop that would do nothing more than provide room to prevent the tire from coming in contact with the fenders.
          'I worked furiously on those things to make sure they didn't do anything aerodynamically,' John Pointer says. 'They were just there to provide an extra inch or two of tire clearance'.
          As Gary Romberg notes, 'There were myths around those things all the way to the racetrack for years! All during the time that the cars were on the race tracks, that was supposed to be one of the major tricks. And that was no more than tire clearance!'"

[pettybird]

Odd thing is the 3/8 scale wind tunnel car has never been fitted with "Exhausters." 

I would think it would be difficult to show airflow through a thick clay shell in a way that sheetmetal could. 

Did the full scale test cars have them?

[RallyeMike]

1. The entire bottom of the engine bay, fender area, and wheel well is open to relieve pressure. A small hole in the top of fender is absolutely nothing in comparison.

2. If in fact they were looking for every small gain (which racers are known to do), they would have put the relief ports at the back of the fenders or hood near the firewall where the pressure is greatest, not halfway to the front of the car where they are not nearly as effective.

It's definitely 100% about tire clearance.

[pettybird]

they would have put the relief ports at the back of the fenders or hood near the firewall where the pressure is greatest, not halfway to the front of the car where they are not nearly as effective.

you'll have to tell nearly every LeMans prototype team since the 70's that they're doing it wrong.

[Daytona Guy]

Dane,  Your looking into the future.      Think as if you are in late 1968..   There is something missing in the original drawing..  Extractors....     Odd thing is the 3/8 scale wind tunnel car has never been fitted with "Exhausters."  There is NO paperwork to my knowledge that shows a E-Series test date or test number for the extractors.  

My only point was the Hellcat - and what was said. How would I answer your questions? Easy. At some point an aero engineer brought it up and they added it, and when they did it it was tested or we would not have the doc that talked about the added effect. Remember these aero guys that were brought in were not car guys. ANY air that you remove from going under the car, or is held captive in the car, is an advantage - these act like suction cups - not just drawing air out, but adding a draw down - for the car. Just like the Hellcat description states @ 7:14. Being in an engineer family (Not aero) ideas and additions are added anytime, if they can prove effective and are easily adaptable. What we are also leaving out, is that this is a "known" advantage to have in racing - They may have simply got this formula and numbers from known tests as well. Some of this can be done on paper with numbers (openings - air speed - extraction rates) If it was a tire issue initially we would not see such a "disregard" for that issue in the test mule, if so, someone had their head where it should not have been

Can anyone do a timeline?

Dane  

[Daytona Guy]

they would have put the relief ports at the back of the fenders or hood near the firewall where the pressure is greatest, not halfway to the front of the car where they are not nearly as effective.

you'll have to tell nearly every LeMans prototype team since the 70's that they're doing it wrong.

Pressure can be released in many places and still be effective - air pressure equalizes (Para shoot) more than just free air flow does. PLus, picking up the air flow right off the tire before it gets trapped, will give you a scavenging effect and aid in the extraction, as in the Le Mans cars. In the middle of the fender is more aesthetic and may have proven more effective in where the air comes out - that then is carried across the rest of the car, thus the Hellcat has them in the same location - just in the hood more because they do not have a top fender per-say.  (PS, I enjoy the dialoged, this is how things on both sides get exposed) Truth-facts- are their own defense.  Where was John Pointer when they where building the test mule, they did not get his memo

Also above,

Dane

[odcics2]

"Exhausters"  =   3% drag reduction.   

That's what it says on the John Pointer authored vintage documentation. 

Greg,   When was that tested?        Gary Romberg and George Wallace both are very adamant that was not the case.
   

Gary talks about it on the Aero Warriors page.
http://aerowarriors.com/aw99.html      Audio only..   Bottom of page on left side.
Gary discusses the fender scoops found on the Daytona and SuperBird. (85 sec. - 1.36MB   

I could not figure out a way to post the audio video for some to hear but the audio is posted on that page.  I know you have heard it.

I'll dig up the original piece of paper.   It was part of the recommended package for the Daytona.

Also - I have the John Pointer hand drawing of the "Daytona".  It has a date on it - I'll dig that up also.

Finally, my car was in the wind tunnel - the full scale Lockheed.   Fred Schrandt told me about that last year.
The lever on the dashboard controlled the 4 air shocks fitted on the car for the testing.
I also found the Romberg penned paperwork for how that was set up, where they bought the parts, etc.

Keep in mind my car rolled out of Nichels Engineering in Nov. 1968 as a Charger 500, going immediately to Daytona for it's first test session
with Baker driving.  (results are on the aerowarrior.com site in the document section)     

[Daytona Guy]

Ok, we have a timeline started...

odcics2, I snuck into your house and took a picture


image hosting free

[Daytona Guy]

Here is a timeline I started after some research - I would like to know when the aero guys were hired to help.

[RallyeMike]

they would have put the relief ports at the back of the fenders or hood near the firewall where the pressure is greatest, not halfway to the front of the car where they are not nearly as effective.

you'll have to tell nearly every LeMans prototype team since the 70's that they're doing it wrong.

The typical LeMans car for many years has had bubbled fenders tightly wrapped all around the tire that trap air. The blow over and drag issue is well known and discussed and is why these cars have fender air extractors. This is absolutely nothing like the wide-open front end of stock car, not to mention the outer aerodynamics also being totally different.

I could see that the initial idea on the Daytona may have been air, but the real world practicality was clearance.

[odcics2]

Ok, we have a timeline started...

odcics2, I snuck into your house and took a picture


image hosting free

 saved me the digging around!    

  (besides all the good stuff is in a bunker in an undisclosed location... seriously!)

[Ghoste]

As it should be, the only other suitable location is a museum and the ideal one is semi-closed.    I hope your bunker is fire resistant too.

[pettybird]

I could see that the initial idea on the Daytona may have been air, but the real world practicality was clearance.

read through previous threads on this topic and look at the pictures of the Isaac and Stott cars and show us how the tires would fit any better in the fenders with the cutouts.  the tire wouldn't fit in the hole...even part of it.