1969 Z28 with unique rear spoiler seen at 1970 Orange County Int. Raceway

[SMKZ28]

Here are a couple of pictures of what appears to be a stock 1969 Camaro Z28 with a huge Top Fuel Dragster type rear spoiler grafted onto the rear.  It was photographed in the parking area for the 1970 Professional Dragster Association Championship held at Orange County International Raceway in Irvine, California. The car was obviously unique enough for a professional photographer assigned to cover the drag racing event to take a couple of pictures of it as he walked through the parking lot.  And you thought crazy rear wings were first seen on souped up 1990's Japanese cars LOL! 

The pictures are a part of the Petersen Automotive Museum Digitization Project: https://archive.petersen.org/pages/search.php

[crossboss]

OMG! This pre dates the 'Rickshaw' Rice Rocket wings! A bit of sarcasm on my part…lol

[firstgenaddict]

We would have called that a JC Whitney special! 
Put down the catalog before smoking that last crack rock...

[william]

These guys definitely didn’t do their homework. Back in the day, Car Life magazine wondered if spoilers worked. They hired an engineering firm to instrument and test several cars; a ’69 Z/28 was one. They tested it w/o spoilers, rear only, front only, both.

Z/28 numbers @115 mph:

No spoilers:    375 lbs lift front, 25 lbs downforce rear
Rear only:      400 lbs lift front, 125 lbs downforce rear
Front only:     225 lbs lift front, 25 lbs downforce rear
Both:             330 lbs lift front, 130 lbs downforce rear

They noted the Z/28 was noticeably unstable with the rear spoiler only. The contraption in the photo would have been a disaster.

They felt the best configuration for the Z/28 was the front spoiler only. The higher the rear downforce on the tires, the less grip available for lateral acceleration. The front spoiler was effective even at highway speeds.

[BULLITT65]

So I a not an engineer. what is the ideal down force? And how did the other cars of the era on the test perform?
thanks

[crossboss]

Boys,
I remember reading an old re-print from 1969/70 concerning the front and rear spoilers/wings. The difference was quite dramatic to say the least. IF memory serves me correctly the cars tested were a 1969 Z/28, a 1970 Mach-1, and a '70 GTO Judge.

[Jon Mello]

Here is said article, which I posted back in 2012...

http://www.camaros.org/forum/index.php?topic=10017.msg73888#msg73888

[crossboss]

Here is said article, which I posted back in 2012...

http://www.camaros.org/forum/index.php?topic=10017.msg73888#msg73888

Jon,
Thanks for posting. That is a different article than the one I have seen. However, it appears the test results are the same. An informative good read.

[BULLITT65]

Here is said article, which I posted back in 2012...

http://www.camaros.org/forum/index.php?topic=10017.msg73888#msg73888

Thanks Jon, I missed that post the first time around.

[william]

So I a not an engineer. what is the ideal down force? And how did the other cars of the era on the test perform?
thanks

Not sure there is one. Would have been interesting if they could have also measured the aerodynamic drag each spoiler added. That's the trade-off. Adding wings, etc. adds aerodynamic drag, slows car down. Front lift is complex to manage. It is produced not only by air flow under the car, but by the front tires revolving at high speed. Penske/Donohue cut a ducting system into the cowl, doors, quarter panels on their T/A Camaros trying to vent the engine bay but the SCCA made them remove it.

Get it right and at some speed, total aero downforce exceeds the weight of the vehicle. Theoretically, it could be driven upside down...

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

[MO]

It's all about G-force.