Daytona - Wind Tunnel Test - UPDATED

[Stevearino]

Would be interesting to see without the front chin spoiler how much lift the front end would generate.

[odcics2]

 

waiting for some numbers!!   

[maxwellwedge]

I left all the charts at home - but can offer a little more today.

This from the fellow that organized the day......

To give you a quick recap of what we learned: the stock '69 Charger we enlisted had its rear end bouncing up and down quite a bit when "driven" at a simulated 200 km/h. Discotona, on the other hand, was pretty steady, largely because of the rear window plug, according to the aerodynamicist—maybe a slight lateral side-to-side wiggling.
The car was of course massively more slippery than the stock Charger: the aero aids added the equivalent of roughly 40 horsepower by reducing overall drag. In terms of downforce and drag, Discotona was also roughly on par with the new Hellcat Charger in almost every respect—it made slightly better downforce over the rear than the Hellcat, probably thanks to the wing, of course.
Unfortunately the aerodynamicist determined it would be impossible to isolate the effect of the fender scoops and prove exactly how aerodynamic they were without having the front wheels rotating at the proper speed—the tunnel had the feature but there was not enough time to prepare for this simulation.......... though that didn't stop Jeff from trying to stick the wand of the smoke machine up in the fender!

[maxwellwedge]

Some smoke....

[charger_fan_4ever]

Awesome.

[JB400]

Hope you have a similar pic with the base Charger   I, for one, am excited that this was done.  Thanks for sharing

[Stevearino]

Time to take it to the Wind Shear tunnel here in the Charlotte N.C. area. They have a rolling deck and wind speeds in excess of 160 mph. Only hitch is it is around $37,000.00 per 12 hr shift in there. Maybe we could get up a collection and put the fender scoop issue to bed once and for all

Great pictures by the way. Thank you for sharing. Can't wait for the data.

[kiwitrev]

  Lacking original design in nose seals area where air could have been diverted or escaped by. As Daytona nose is molded in.Cause any variations in readings

also has different wheels

[tan top]

 this is good stuff          ..........

[XS29L9B2]

very nice picture

[Ghoste]

Its interesting to me that the Daytona was on par with the Hellcat and yet when it was engineered Chrysler didn't even have a wind tunnel of their own.  It also occurs to me that said Daytona engineering was done in a university wind tunnel back in the day.

[maxwellwedge]

Here is some data at 155.5 MPH (250 KPH)...........

[68pplcharger]

great data, show how different the street car is from the race car... 

[Stevearino]

Okay.  I am used to looking at downforce as negative lift or positive lift. Since this sheet is calling out the downforce as downforce  does the negative number in the front indicate lift or is that negative lift indicating downforce. The reason I ask is because there is a positive number on the rear which says depending on the data interpretation there is lift on one end of this car. I would not think it would be on the wing end. 

[Mike DC]

  
(Somebody correct me if I'm wrong here)  


The wing & nosecone were designed to work at the body rake angle that they had already determined was best during the C500 project.  Something like 1.5 degrees down.  So in practical terms the Daytona street car was angled too far up in front (at normal ride height) for the aero mods to really shine.  



I suspect this street/race discrepancy would have been much more pronounced on the Superbirds.   They were raking the winged Plymouth NASCARS much more severely than the Dodges.  The C500 project was allowed to do anything they wanted with the rear window plug.  So they made a very low-angle window and extended the plug into the trunklid real estate.  

The Plymouth wing car project was subject to some cost-cutting compromises with their higher mandated production number.  So the engineers weren't allowed to slope the Plymouth rear window back nearly as far as on the Dodge (the Plymouth trunklid opening had to stay stock).  This demanded a more sharply raked stance on the whole car to keep the airflow sticking to the rear window as it trailed back off the roof.      

---------------------------


As for the fender scoops, I still say data pulled off a street car is not really viable.  The NASCARs had no inner fenderwells, bigger tires, much lower front stances, and the under-scoop holes were about 3x as large.  

[maxwellwedge]

I agree on the scoops because of the absence of inner fenders etc.

The exercise was basically a comparison between a Daytona, the old Charger and a new Charger......and considering what wind tunnel time costs.....it was an opportunity that had to be jumped on no matter what......even for just the "cool factor".

Funny tid-bit......the engineers did not want to do a 250 kph test fearing the car would fall apart or worse. Once they looked in the trunk and saw how securely the wing was mounted they went for it. A friend told them that this is old school great Chrysler engineering and it wasn't going to fall apart like some new plastic piece of crap...lol.

[68pplcharger]

 
(Somebody correct me if I'm wrong here)  


The wing & nosecone were designed to work at the body rake angle that they had already determined was best during the C500 project.  Something like 1.5 degrees down.  So in practical terms the Daytona street car was angled too far up in front (at normal ride height) for the aero mods to really shine.  



I suspect this street/race discrepancy would have been much more pronounced on the Superbirds.   They were raking the winged Plymouth NASCARS much more severely than the Dodges.  The C500 project was allowed to do anything they wanted with the rear window plug.  So they made a very low-angle window and extended the plug into the trunklid real estate.  

The Plymouth wing car project was subject to some cost-cutting compromises with their higher mandated production number.  So the engineers weren't allowed to slope the Plymouth rear window back nearly as far as on the Dodge (the Plymouth trunklid opening had to stay stock).  This demanded a more sharply raked stance on the whole car to keep the airflow sticking to the rear window as it trailed back off the roof.      

---------------------------


As for the fender scoops, I still say data pulled off a street car is not really viable.  The NASCARs had no inner fenderwells, bigger tires, much lower front stances, and the under-scoop holes were about 3x as large.  

Okay.  I am used to looking at downforce as negative lift or positive lift. Since this sheet is calling out the downforce as downforce  does the negative number in the front indicate lift or is that negative lift indicating downforce. The reason I ask is because there is a positive number on the rear which says depending on the data interpretation there is lift on one end of this car. I would not think it would be on the wing end. 

Stevarino you are correct with your initial thoughts. The front actually has lift and the rear has a downforce. This is due to the stance of the car in street form. The car is to high in the front to take advantage of the overall aerodynamic design of the Daytona. I believe Mike DC is also correct about the size of the underscoop holes. The holes would help reduce pressure under the car as well as evacuate hot air from the motor and radiator with the removal of the inner fenders in the race car version. The bigger holes would allow for better pressure reduction. I'm sure the hole sizes in the race car were optimized for the size scoop that was used.

[odcics2]

Maybe someone can do the math.

If we now know the drag of a Charger Hellcat, and it ran 204 on a 10 mile oval, with a claimed 707 HP,
what is the drag number of the race #88, which did 200 with 585 HP ?  (on a smaller track, too) 

[Aero426]

The Daytona street car small front spoiler and positioning of such would likely make a significant difference in the numbers.    

[odcics2]

The Daytona street car small front spoiler and positioning of such would likely make a significant difference in the numbers.    

Low = Fast

[Stevearino]

The Daytona street car small front spoiler and positioning of such would likely make a significant difference in the numbers.    

I work with a guy who worked on a restoration up in New Hampshire back in the 80's. They took the car out before it was totally done and it was a handful to drive at speed. They thought " Well these old cars......"and such and such. He said after it was done and the chin spoiler was installed the faster they went the better the car behaved so even that little thing is helping more than one would think.

[Ghoste]

Oh for sure.  Just look at all the new cars that have a tiny chin spoiler under there to help with fuel mileage.

[DAY CLONA]

The Daytona street car small front spoiler and positioning of such would likely make a significant difference in the numbers.    

I work with a guy who worked on a restoration up in New Hampshire back in the 80's. They took the car out before it was totally done and it was a handful to drive at speed. They thought " Well these old cars......"and such and such. He said after it was done and the chin spoiler was installed the faster they went the better the car behaved so even that little thing is helping more than one would think.

It's been some time since I've read the Chrysler/Wichita  G Series (1971) wind tunnel test results, (granted it was done on 3/8 scale models of the F  and proposed G series cars) but IIRC the front spoiler was never a design consideration, it became a necessity because the undercar air turbulence was having a negative effect on the rear wing downforce values

[odcics2]

the front spoiler was part of the recommended race package, even before they added the wing.   

[C5X DAYTONA]

the front spoiler was part of the recommended race package, even before they added the wing.   

When was the test done on the exhausters?   The 3/8 car never had any holes for exhausters on the fender.    As far as I know a full size Daytona was not put into a wind tunnel till after production started.