STYLE AND FUNCTION
By Wayne D.
An inside look at the development of the Camaro's spoiler
equipment by the author of
"Camaro- Untold Secrets"
||The Camaro's optional spoiler system
is a true example of style and function... A harmonious addition that blends aesthetics
into real performance.
aerodynamics plays a large part in how a car handles on the highway, and an even larger
part on the race track. It's from actual racing experience that most high performance
options for the '67-'69 Camaro were derived and the Camaro's aerodynamic spoiler equipment
is one of the best examples of Chevrolet's race bred technology.
When it came to
making the Camaro competitive, Chevrolet was serious, at both the consumer level and on
the track. And it was through racing that Chevrolet was able to successfully promote the
Camaro and tap into the fast growing youth market.
The formula was simple, Chevrolet put
together the Camaro Z/28 package to compete against their rival, the Ford Mustang in the
Sports Car Club of America's Trans-Am road racing series.
IT ALL BEGAN...
Back in September
of 1966, when the Camaro Z/28 package was first being put together, Chevrolet called on
Engineer Paul Van Valkenburgh to evaluate the Camaro for high speed stability and to
suggest "aerodynamic fixes" if necessary. Chevrolet Engineering was meticulous
when it came to preparing the Z/28 package for competition. The concentration was on
winning, and every aspect of vehicle dynamics was addressed accordingly.
The opening event was to be held at
Daytona where speeds are in excess of 140 MPH and they needed to be certain that the
Camaro would be able to stick to the track. It was Chevrolets experience that production
vehicles tend to exhibit front end "lift" which becomes excessive at high speed
creating unsafe conditions in racing.
Prior to the Camaro inquiry, there wasn't
much aerodynamic study done on production automobiles, the Corvair and Corvette being the
two notable exceptions. The Corvair was found to wander excessively at highway speeds,
dangerous nose lift was a real concern and for this reason aerodynamic studies were
performed inside engineering. In those studies, it was determined that a front valance
panel (plow) corrected this detrimental effect by decreasing under body air flow and, as a
result, it became a production part of the Corvair. It was from this early developmental
work that the Camaro would later benefit. The Corvette was a slightly different matter in
that it was studied during competition at race tracks and again treated to a similar fix.
Although effective, both of these examples
were tested crudely by trial and error. Essentially guess-tamating which aerodynamic fixes
might work best. The Camaro, on the other hand, was more scientifically studied using a
scale model in a wind tunnel to determine the base aerodynamic qualities. Lift was
measured and, like most production vehicles, determined to be greater than the acceptable
limit for racing at high speeds.
Scale model in wind tunnel helped establish aerodynamic base line
from which the spoiler equipment was developed.
various sizes, angles and shapes were applied to the Camaro front end and the most
effective was chosen. Once the problem of nose lift was countered using the front valence
panel, engineers began contemplating how an inverse effect or -Down force- could be
created and utilized to increase high speed cornering traction. The problem was not so
much how to get down force as it was how distribute it between front and rear tires, and
how to minimize the effect on air drag.
The first front valance was so effective
that it produced massive over steer. To counter that, a smaller unit was substituted until
the problem was corrected. Slight understeer is always more desirable for better handling.
A rear spoiler was then added for additional downforce but the car began to understeer
badly. It then became a balancing act to get the right combination of front and rear
aerodynamic effects for vehicle stability.
The measurable effects of the "plows
and tails" were recorded and the results with recommendations sent to Chevrolet's
Style group for further consideration and development. The Style group determines what
will and will not work from a stylistic stand point based vehicle lines and current trends
of consumer acceptance.
Final configuretion on engineering Z/28
Graceful lines "blend in" to enhance the body design.
initial recommendations (specifications) submitted by Van Valkenburgh would have been
better in terms of optimum effect, the group made the necessary aesthetic compromises,
blending lines and altering dimensions in order to create a design that would be
acceptable to the consumer. Remember, prior to the Camaro, only "race cars" like
Chapparals wore spoilers. They just weren't seen on production vehicles and were at first
perceived as a radical departure from the "norm". A remarkable contrast to today
where every other car, including four door sedans, sports a whale tail!
about the effectiveness of this special equipment, Van Valkenburgh emphatically states;
"The front valance and rear deck spoiler were more than mere styling gimmicks. They
actually made a measurable contribution to cornering and stability at highway speeds and
were indispensable on the race track".
More than a gimmick... in this case a bill
INDEPENDENT TESTS VERIFY...
independent tests conducted using a 1969 Camaro Z/28 clearly demonstrate the practical
value of the optional spoiler equipment. The testing was conducted by the editors of CAR
LIFE magazine and the results appear in the June 1969 issue.
In order to standardize the tests, a
single Camaro Z/28 was evaluated both with and without the factory spoiler equipment
installed. This testing method eliminated any vehicle/chassis variations that may occur
between two different vehicles which can "factor in" affecting the validity of
Parameters measured were lift and
downforce. The two most important aerodynamic factors that affect traction and handling at
speed. Speed intervals of at 65, 85, and 115 mph were chosen as a practical range of test
points for analysis and comparison. The 65 mph mark representing a typical highway speed,
85 as the intermediate passing or top crusing speed, and 115 as an average race speed on
medium and short road race courses.
In making value
judgements on the effectiveness of the spoiler equipment, the desired results would be:
1. Normally, a slight lifting of the nose
if there had to be a choice between nose or tail lift at speed;
2. Ideally, the nose would be forced down
by the flow of air and the tail would be forced down even further than the nose.
THE RESULTS... (at 115 mph) (SEE GRAPH)
front or rear, the Camaro exhibited an excessive 375 lbs. of lift at the front. The rear
had a positive 25 lbs down force which is typical for notchback cars.
and rear spoiler equipment installed, the vehicle exhibited a marked improvement overall.
Lift decreased to 330 lbs. at the front and downforce at the rear increased to 130 lbs.,
resulting in a balanced and completely tractable vehicle.
produced the desirable effects of increased traction along with a slight understeer
condition. In controlling the lift of the nose so well, there was an increase in stability
that a sensitive driver is able to feel even at moderate speeds.
In referring to the graph, It
should be noted that the effectiveness of the spoiler equipment is proportional to vehicle
speed. The faster you go the more effect the equipment has. The best part is it looks as
good as it works!
THE CELEBRATED DEBUT
equipment first appeared publicly November 1966, on a 1967 Camaro Z/28 during a press
conference at Riverside California. The event was hosted by Chevrolet solely to introduce
the new Z/28. At that time, a three page "Technical News" handout was
distributed describing the new Z/28 with its "Special Equipment" and options.
As it turns
out, not all of the special equipment listed became part of the RPO Z/28 package. Some
ended up as separate RPO's and others as service options. The spoiler equipment was listed
as a separate option (RPO D80) and referred to in the handout as auxiliary
"aerodynamic" body panels.
The spoiler equipment did not appear in
the regular 1967 or 1968 Camaro brochure. It was however, featured in a separate 1968 Z/28
brochure as optional equipment available with RPO Z/28. For 1969, it appeared in the
Camaro brochure as optional equipment available on all Camaro models and, later in the
year became a part of the Z/28 package.
early 1969 Camaro's ordered with RPO D80 Air Spoiler equipment came through with the
narrower 1968 style spoiler as can be seen on the back of the 1969 Camaro dealer brochure.
Therefore, if your 1969 Camaro was made very early in the model year and has a narrow
spoiler, chances are that it is correct and was installed at the factory.
The strangeness of
seeing the narrow spoiler on the rear deck of a 1969 car puzzled many restorers and
experts, leading them to think that someone had later "added" the wrong piece
and in turn would "correct" the mistake by substituting the wider piece.
Unfortunately, these corrections have lead to even more confusion since it would then
appear as if fewer early cars were produced with the narrow spoilers then actually were!
|THE DYNAMICS OF AIR FLOW AND ITS
EFFECTS ON AUTOMOBILES...
causes lift? To some degree, body panel shape and to a larger extent, air that passes
through the opening of the grille and under the front end sheet metal. At speed, this
massive air stream builds up tremendous pressure under the hood where it is forced to exit
rearward, below the chassis, resulting in body lift.
|We can effectively counter lift by limiting the amount of air
flowing under the front sheet metal with the use of "dams" and by down-sizing
the opening in the grille. Furthermore, we can relieve pressure under the hood by
incorporating exhaust vents in the fenders such as the ones used on the Trans-Am Firebirds
and Corvettes. Any remaining lift may be countered by applying down force using additional
aerodynamic "spoiler" devices at the front and rear of the vehicle.