DECH
Rear Wing
Rhino Brothers Racing
Aerodynamics & Exterior
DECH
Rear Wing
Currently, the only major aerodynamic improvement has been the addition of a dual-element wing, build by DECH Motorsports in Canada, called the AFD-IV. Although somewhat detrimental to top speeds at the end of the straights, the wing has proven to make the car faster everywhere else on the course. And it's the total lap time that counts, not the top speed. The wing is a dual-element design, which refers to the dual air foils, and is a more efficient design than a single airfoil design for high downforce and low drag applications. The top airfoil also has a 1/2" Gurney flap, which further adds downforce by creating a high pressure zone above the top flap.
The wing has also served to make the car more stable at speed. The aerodynamic loading of the wing more than cancels the lift inherent in Mustangs, and has in fact planted the rear so well that it in many ways makes up for the poor suspension geometry. However, in the long term, I still plan on correcting the rear suspension, so that the car can stick using mechanical grip, and not rely on aerodynamic downforce to stick. This should allow me to "turn down" the wing, creating less drag, but still keeping the confidence and stability that the wing instills.
The wing's struts
and airfoil's are made of aluminum extrusions, while the end caps are made
of a complex laminate. The entire wing is incredibly light, extremely
strong, and was beautifully finished by DECH. It also features an
adjustable angle of attack, so you can tune the car with the wing.
The wing is by no means small. As you can see, it is as wide as the car. DECH can make the mounting for just about any vehicle, and can locate it on the vehicle depending on whether the priority is aerodynamics or cosmetics. The struts for this wing were made to emphasize the downforce ability of the wing. This is why the wing is so high and so far back. Moving the wing down and/or forward would put the wing in turbulent air, and seriously encroach upon it's ability to work efficiently at making downforce with minimal drag.
The entire DECH wing was assembled onto an LX spoiler, which is a far
better spoiler then the GT spoiler or the Cobra spoiler, neither of which
actually do any real "spoiling". (A spoiler is designed to "spoil"
the high-speed low pressure air running down the rear glass, and creating
lift. A wing, in contrast, is designed to actually create downforce,
rather than canceling lift.)
Fender
Extensions
I did some major modifications to the front fender extensions, which, although required for wheel clearance, were done in such a way as to encourage air to slide around the car, rather than getting caught up in the wheel well turbulence.
This modification required running an aluminum "stretcher bar" from
the radiator support to the back corner of the fender extension.
This forces the corner of the extension outward, giving more tire clearance
during turns. This is necessary in a car with the Griggs front suspension,
which pushes the front wheels forward in an effort to get more caster and
better weight distribution.
Chin Spoiler w/ Integral Splitter
Currently,
there are more aero projects in the works. (Do you count removing
the windshield wipers??) I am in the middle of fabricating a chin
spoiler for the car. This has been a work in progress for quite some
time, and may not get completed in time for this season. The plans
are for the chin spoiler to extend down from the stock GT bodywork about
4", and have a splitter that extends out about 3". If it is done
right it can actually create downforce while reducing drag, which is clearly
a win-win situation. Not having access to a wind tunnel, I clearly
can not optimize it, but I will get as close as I can with some "guess
engineering". The spoiler also needs to be easily removable, since
it will not make it on the trailer with it in place. I plan on attaching
it with about 10 - 14 DZUS fasteners. The following pics show the
progress of the project.
Here you can see
the distinct bottom plate (splitter) and the vertical spoiler portion.
The bottom plate is made of 0.060" aluminum. It was originally designed
to be adjustable, (you can see the elongated holes that were designed for
this adjustment) but that idea quickly went the way of the dinosaurs when
the complexity got to be too much.
The upper spoiler portion is being formed from 0.010" aluminum sheet
to start with. This light material is not strong enough, rigid enough,
or abrasion resistant enough to survive on it's own, but it will get the
ball rolling. My original plan was to fiberglass over both pieces,
but that it is far too involved, too heavy, and to expensive. At
the suggestion of Bob Hahn, who has quite a nice spoiler himself, I will
be covering the spoiler in 0.070" plastic sheet, to give it rigidity and
toughness. I think this design, as Bob pointed out to me, will be
long lasting, and easy to repair. The spoiler/splitter is seen here
temporarily Cleko'ed to the car. When things get finished, each Cleko
will be replaced with a DZUS fastener. If you look closely, you can
see that I siliconed the seam between the bottom plate and vertical plate,
to prevent air leakage, and to help hold the two pieces together.
This stuff is strong!! It will also help dampen any vibrations in
the splitter.
This is a picture
of the splitter off the car, while I was working on it. You can see
at this point the two plates were Cleko'ed together, a method of temporary
attachment that I have become quite fond of lately. The tools and
methods aren't the greatest, and the craftsmanship sure isn't "A" grade,
but I think the end result is coming along quite nicely.
In it's permanent form, the Cleko's will be replaced by rivets, and
many more will be added to distribute the down-load as best as I can.
Notice how many tabs needed to be cut to allow the aluminum to be bent
into gentle curves to match the profile of the stock GT bodywork.
A picture of the
splitter from a mouse's eye view. You can see all the rivets were
run upwards, rather than down, to minimize the number of things protruding
downwards. You can also see two air vanes welded to the bottom of
the splitter. I can not put the splitter right on the ground due
to ground clearance issues, and the vanes were added to encourage air that
did get under the splitter to go around the car and the tires, again in
an attempt to minimize air pressure under the car.
The vanes were also designed so that if the car did bottom on the splitter,
it would hit the vanes. Why is this good? First, they are easily
replaceable if they wear due to ground contact. Second, they transfer
the loads into the stronger area of the splitter, rather than hitting in
the front of the splitter, which could apply a lot of torque to the mounting
rivets.
The car's paint sure looks good, huh??!! I think that there might be a
paint job in my future...