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WHAT IS DOWNFORCE? The term “downforce” in racing is used to describe the downward force of the air on the body surface as air passes over it at speed. Downforce can be applied anywhere on the body front to rear. The more angle of the forward facing surface, that the air is passing over, the more downforce is being applied. At the same time, more angle of an opposing surface to the air will create drag. Downforce will create more traction but drag will slow the car.
The goal is to apply as much downforce to a particular area of the car body to achieve the handling feel you want and create as little drag as possible. That can actually be a fairly complicated process and can only be judged properly with very sophisticated devices in a true wind tunnel.
Of course Nascar teams with unlimited budgets spend bajillions of dollars to figure that out. Not very practical for RC racers. Nascar also does extensive wind tunnel testing to make the bodies as equal aerodynamically as possible.
Here at McAllister Racing we follow the shape trends of Nascar, not only to have a realistic look for our scale racecars but to take advantage of Nascar and their teams research in aerodynamics. That’s why we have the most scale appearing bodies for oval racing. HOW TO USE DOWNFORCE? Since applying downforce to a body will create better traction, we need to figure out how and where to apply it. Basically a race car handling is described as oversteer, understeer or neutral. Oversteer in aerodynamic terms is more front downforce (less rear downforce), understeer would be more rear downforce (less front downforce), and neutral would be a good combination of both. Each body will exhibit a certain characteristic among the three possibilities mounted on a car with a given set up. (Always keep in mind that aerodynamics is only a part of the combination needed to set a race car up properly. Don’t expect aerodynamics to work in a vacuum and solve all your problems) The aerodynamics can be greatly affected by adjustments to the aerodynamic components of the body to achieve oversteer, understeer or neutral handling. We’re lucky compared to the full size Nascar teams that do not have these adjustments available. BASIC BODY AERO COMPONENTS -BODY MOUNTING & ANGLE ATTITUDE OR “RAKE” -FRONT AND SIDE SKIRTING -REAR SPOILER -WIRE MOUNTED WING |
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BODY AERODYNAMICS |
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USING THE AERO COMPONENTS Body Mounting and Rake Mounting the body correctly is very important. Fitting the body so the tires have good clearance (no rubbing) and centered over the tires is the first step to proper handling. If anything is rubbing or dragging there’s no need to even make chassis adjustments, the car won’t work right at all. Smooth, straight, clean edges every where around the body will be less disruptive to air flow creating more speed. Expose as little as possible of the body posts. It’s popular to use buttonhead screws instead of body clips. Great aerodynamically...not as substantial in crashes….driver’s choice.
Rake is the angle the body is mounted on front to rear. Very simple...Front lower, rear higher equals more over all downforce (if using a rear spoiler). Good for shout tracks. Front higher, rear lower equals less downforce over all and much less drag. Good for very long high speed tracks. Plus the infinite variations in between. Another subtle adjustment with “Rake” is the height of the rear spoiler.
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Front and Side Skirting Using the lower skirting to seal air off will make a cleaner air flow and may help with some extra downforce with little drag penalty, but…. DO NOT have any lower edges dragging the ground! This is like dragging an anchor around the track and most important, any time your chassis or body contacts the racing surface , you have just negated all that expensive, high tech suspension under the body. Not a good idea. Always maintain ground clearance, especially in the corners where the body rolls the most and the suspension is needed the most. Cutting out the rear of the body and leaving the rear quarter panels extend down as sail panels is popular in some areas. We’re not convinced of the validity of those ideas and prefer the scale appearance where the cut lines are indicated on our Stock Car bodies. |
