The Real Scoop on the Scoops?
Greg
Kwiatkowski's Discovery
Regular
visitors to the Aero Warriors site are familiar with Greg Kwiatkowski, as he
has contributed a great deal of interesting and unusual material to the site.
Greg's prototype
Daytona wing
and his recent find and purchase of the real #88 racing Daytona have been recounted here,
and several documents and photos that Greg has collected
over the years are also on display.
Because of Greg's enthusiasm for Chrysler products
(as well as the fact that he works for them), Greg has had the opportunity to
meet and speak with many of the people involved in the development of the Dodge
Daytona and Plymouth SuperBird. And one of these
encounters some time ago lead to a very interesting find about the cars' fender
scoops!
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To
help with readability, the scoops paperwork Greg found in Larry Rathgeb's files has been recreated here. Notice the data
shaded in purple - the scoops (exhausters) are credited with a 3% reduction
in drag! A photo of the actual document is available. |
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In
1986, Greg was offered the opportunity to look through some old Chrysler
paperwork belonging to Larry Rathgeb. Those familiar
with the winged cars will remember that Larry was in charge of engineering for
Chrysler's stock car racing program during the time that development work was
being done on the cars. Greg made copies of much of Larry's rare documentation,
including one piece of paper which is particularly significant to this
discussion. The document has been recreated at left, and although it carries no
date or identifying signature, it was found among documents that Larry told
Greg he had authored during the Charger Daytona development. Look closely at
the area shaded in purple.
The document seen here is pretty self explanatory.
A Charger 500 (presumably a race prepared car) was used as a baseline for
aerodynamic testing, with changes to the Charger 500 evaluated in relation to
the drag produced when it was in the Charger 500 configuration. So, in the case
of the first change to the car's configuration, the Charger 500 front end was
apparently replaced with a long nose that included an optimum front spoiler
set-up (whatever that was). The accompanying entry from the "Effect"
column shows that this nose combination exhibited 9.5% less aerodynamic drag
than the standard race Charger 500 front end. Several tests were obviously
conducted, with the one most germane to this discussion shaded in purple. This
particular entry concerns itself with the scoops (or "exhausters" as
they are referred to here) and the
aerodynamic advantage they afforded. As recorded in the "Effect"
column, a 3% reduction in drag was noted when the exhausters were added to
the baseline Charger 500 set-up! And of course this directly contradicts
what Chrysler has been claiming about the scoops (exhausters) for the past 30
years.
Because there were no pictures or drawings included
with the Rathgeb paperwork, some may question whether
the exhausters mentioned were in any way similar to what actually ended up on
the Daytonas and SuperBirds.
And if they weren't, then perhaps "apples and oranges" are being
compared here. If that really is the case then, this document still provides
very important information. It discloses that Chrysler had some device, called
an exhauster, that when mounted above the front tires reduced drag by
3%. And wouldn't it then be logical to conclude that Chrysler, knowing this,
would not end up mounting something on the cars' front fenders that returned
any less than this 3% drag reduction? So whether the exhausters mentioned in
Larry's paperwork are similar to or very different from what eventually showed
up on the cars, it seems reasonable to conclude that the exhausters actually
found on the race cars yielded no less than a 3% drag reduction.
And yes, there is an assumption being made that the
document presented here is genuine. It seems extremely unlikely that this
document would have been created by Larry Rathgeb,
Greg or anybody else in order to rewrite history on the scoops. For the purposes
of this discussion, the document is accepted as genuine.
How
The Exhausters May Have Reduced Drag
Generally
speaking, reducing air flow under racing vehicles will improve their
performance. In the case of the winged cars, air flow under the vehicles caused
drag because air collided with the aerodynamically "unclean"
undersides. One result of this disruptive air flow under the cars was probably
some degree of upward force being applied to the vehicles' bodies because of
"trapped" air. Front spoilers, found on many racing automobiles
including the Daytona and SuperBird, were designed to
prevent or "spoil" much of the air flow underneath the cars. Yet
another method to reduce air flow under stock car racers was to lower them, and
that is where this particular explanation is rooted. The exhausters (or more
correctly the holes in the fenders beneath them) provided a pathway for air to
escape from under the cars, where it would otherwise be trapped as the autos
moved at high speeds. With air trapped under the vehicles, their bodies would
ride higher than with the exhausters, resting on this cushion of trapped air.
And because the bodies were setting higher on this cushion of air, even more
air could flow underneath them. Providing an escape path for this trapped air
allowed the bodies to set lower than they otherwise would, and thus less drag
was produced because of the reduced air flow under the cars.
And why were the exhauster scoops mounted over the
fender holes? A vacuum would be created directly behind the trailing edge of
the scoops as the air rushed by. This small vacuum may in fact have aided in
air extraction from underneath the cars. Without the scoops, any vacuum effect
over the tops of the fenders would probably have been much less pronounced, if
not totally non-existent. This same principle is used in NASCAR's Winston Cup
series today, as the exhaust headers are cut in such a way as to be flush with
the rocker panels of the cars. The air rushing by helps "pull" the exhaust
out of the headers.
Also note the name exhauster. Webster's
Dictionary defines exhaust (including the noun form exhauster) as
"to let out or draw off...to draw out the contents of...a conduit through
which vaporous gases are emitted...an apparatus for drawing out noxious air or
waste gases by means of a partial vacuum..." The name exhauster
seems to support the contention that the scoop devices were in place to release
something from somewhere, like air from underneath the front of the winged cars
perhaps?
Other
Benefits
An additional benefit of the exhausters, and one
unrelated to drag, is a reduction in ride height which in turn lowers the
winged cars' center of gravity. And generally speaking, the lower the cars'
center of gravity the better, especially as it relates to their ability to
handle turns. Lessening air flow under the vehicles also allows greater control
over the attitude or "rake" of the cars, as the bodies in some cases
would probably have a tendency to be levered up by air flow while moving
forward. By lessening total air flow under the cars, a more consistent rake
angle could be maintained, which was especially critical for the winged cars.
As alluded to by Chrysler aerodynamicist Gary
Romberg in two of the quotes above, the exhausters were the subject of
speculation among Chrysler's racing competitors. To the extent that the
exhausters distracted the competition and "psyched them out", they
were also arguably of some benefit.
And it should be stated clearly somewhere in this
article that the exhausters may well have provided tire clearance, although
calling that their only function (or even their primary function) is what
Greg's paperwork has called into question. It would certainly be ironic if the
needed tire clearance was necessary only because of the reduction in ride
height due to the functioning of the exhausters.
Chrysler's
Reaction?
What is Chrysler's reaction to Greg's discovery? He
hasn't approached Chrysler engineers (past or present) en masse with the
paperwork, although the few he has asked about it have had no response. If and
when the opportunity presents itself, Greg will contact other engineers that
worked on the cars to see what reaction they might have. If appropriate to do so,
their responses will be reported here.
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Conclusion
Greg Kwiatkowski's discovery of the air exhauster
test results certainly provides ammunition for those that feel there is more to
know about the "why's" of the fender scoops than Chrysler's tire
clearance explanation. Whether the drag reduction benefit the exhausters
offered has been a jealously guarded Chrysler secret for 30 years or just a
small bit of data lost in the hectic environment of the cars' development and
manufacture remains unclear. Hopefully someone from Chrysler will now step
forward and help put Greg Kwiatkowski's discovery in perspective. But until
then, the exhausters continue to be a bit of a mystery.
The author attended the 1999 Mopar
Nationals in Columbus, Ohio and not surprisingly several of Chrysler's new and
exotic offerings were on display, including several Dodge Vipers. The photos at
left document an especially interesting aspect of both the street Viper (top)
and its racing counterpart. Notice the louvered openings on the front fenders
above the tires. They obviously aren't for tire clearance, as the closely spaced
transverse louvers would impact the tires just as a solid fender would. Why
these fender openings appear on some of Chrysler's contemporary high
performance vehicles is certainly worth pondering. Perhaps the Internet
District Court's indictment that introduced this article is closer to the truth
than most realize!
See: http://aerowarriors.com/tsots.html
