What is Downforce?

The term "downforce in racing is used to described 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 and rear. The more angle of the forward facing surface, that air is passing over, the more the downforce is being applied. At the same time, more angle of an opposing surface o 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 as 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 Mc Allister Racing we follow the shape trends of NASCAR, not only to have 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 taction, 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 means more front downforce (less rear downforce), understeer would be more 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 aerodynamics 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"

  • Font and Side Skirting

  • Rear Spoiler

  • Wire mounted wing

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.

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 thevalidity of those ideas and prefer the scale appearance where the cut lines are indicated on our Stock Car bodies.

Rear Spoiler
Another huge adjustment we RC racers have that the Cup Boys don't. We can adjust the angle and height to our liking ... even remove it if we want. A lot of Stock class racers remove them for lessdrag in a limited horsepower situation. You still have to get the car to handle with other adjustments ... but the theory is correct.

Just remember, higher spoiler and/or more angle equals more rear downforce and more drag. Lower spoiler nd or less angle equals less rear downforce and ess drag. Don't forget we are talking about front to rear balance on handling. Likewise, ore rear downforce has the same meaning as less front downforce. It's really a matter of orientation to the components you are adjusting.

Wire Mounted Wing
This is the biggest departure from the actual NASCAR bodies we have on RC Cars. Not necessarily a good one we might add, since they are ot scale appearing. However if the rules allow them, and most do, use them! It's a very adjustable tool to create rear downforce and stability. There are a variety of clear plastic models available with a wide variety of rear kickups, side board shapes and sizes. Experimentation is the key here. Since there are so many variations possible you can try a lot of possibilities. As always, more angle and/or higher rear kickup equals more downforce and more drag. Less angle and/or less rear kickup equals less rear downforce and less drag.

The big difference from the spoiler is being mounted higher in cleaner air for more efficiency and the ability to move the wing around. Just moving the wing backward relative to the body will create more rear downforce with no extra drag penalty because of the leverage. Moving the wing forward will create less downforce. It's best to keep the wing no higher than the roof of the body. This allow god air pickup but doesn't create a huge problem with keeping weight low on the car.

The side boards and flat surface of the wing act as rudders or stabilizers like an airplane. They smooth the airflow which has a stabilizing affect on the overall handling... very important for high speed ovals. The Cup Guys would be jealous. They will soon have a slimmed dow version on the NASCAR COT (car of tomorrow) car in 2007. Always keep them straight with the flow of the air... if not you can call them barns doors or air brakes.


Finished body in race ready form...Note ground clearance of skirting, consistent tire clearance in wheel cut outs, position of rear wing and slight body rake.

In Summary

Any current stock car bodies can work fine n a well adjusted contemporary chassis using the adjutment tools available. Don't expect to just change to another style of body and get instant results. The correct setup is there, you just have to find it. That should ba art of the fun after all.

We recommend finding a body style you like the looks of, then work with the adjustment tools described here to create the handling balnce that suits your driving style. Remember, aerodynamics is only part of the overall handling equation. Changing conditions occur so be ready to adapt with your knowledge of aerodynamic tools.