Aero, Wings, and Wicker
These are old articles for previous models of iRacing cars that may have changes significantly. This was all designed for a TNT Racing app in 2015, but is now free to the public as a general guide. Some links may be broken and can no longer be updated.
The aero package for the FW31 provides the driver with options to reduce drag for increased speed at the expense of downforce. Options available include Downforce Trim Level, Base Front Flap, Flap Adjuster Dial, and Rear Wing Wicker. The downforce trim should be high unless the track has an abundance of high-speed straights where the lack of drag compensates for lost time cornering. Monza is currently the only track that benefits from a low-DF package. The med-DF package is useable at Monza, but no other tracks to date benefit from the med-DF trim level. Stick with high-DF levels at every other track.
Base Front Flap
The base front flap and Flap Adjuster Dial work in concert to provide the driver with the total front flap in use. Adjust the dial to a medium value (around 4) to allow for pit-stop changes should you need them. Typical front flap is a maximum of 30 degrees. Any reduction in total front flap will decrease front-end downforce which results in a tighter feel. It is a viable option. If the car is too loose, there are many ways to correct this and it is recommended that the driver choose from options other than front flap reductions. Rarely does a top-level driver use anything other than full front flap. The only situation requiring reduction of front flap is the use of a different downforce trim package. LDF and MDF settings cannot use the full 30 degrees of front flap as it heavily oversteers with the lack of DF on the rear of the car. A low DF setting with around 20 degrees is stable. A med DF package with 26 degrees of front flap is also stable. When choosing a different overall downforce trim level, a different front flap is required. The flap adjuster dial is the preset in-car setting that allows the driver to manipulate the front-wing level during a pit-stop. If your car has sustained front or rear-end damage resulting in an oversteer or understeer condition, you can select a different front flap angle during your pit-stop. Hopefully during the pit-stop the front wing is replaced (which happens in just a few seconds). If not, the adjustment can be made and the effects felt immediately. A rare option could be the use of extra front flap if the driver feels that traffic is a concern and front-end grip is at a premium. Realize that if you make this change, you may subject yourself to massive oversteer complications as each adjustment is a full degree of change. It should be noted that the driver can never exceed 30 degrees total front flap using the dial in the pits.
Rear wing wicker is a strip of material placed on the top of the horizontal rear wing. It is designed to manipulate airflow resulting in variances in drag and downforce on the rear of the car. More positive wicker generates significant amounts of downforce, but also generates lots of drag. More negative wicker has the opposite effect, resulting in a loose condition, but greater straight-line speed. Track study and a theoretical approach is best for determining starting parameters for this tool. If the track has an abundance of high-speed sections and a loose car is preferred, this should be set to reduce drag (lower wicker value). Keep in mind that wicker is not the only tool the driver can use to gain downforce or speed. There are varying methods for attaining speed, but wicker is one of the most noticeable. Tracks that have lots of slow speed corners requiring rear grip should be attacked with some wicker. If the trade for wicker can be negated by the driver, strive to drive comfortably with a lower wicker setting until you find the edge of available grip.
The aero-calculator is a seldom-used tool that really needs to be highlighted and reconstituted into tool bag. The calculator determines front DF percentage (higher number means more oversteer) and a downforce to drag ratio. The inputs are RH at speed for the front and rear of the car. Don't use static garage RHs to calculate your DF/drag levels!!! It is designed for dynamic at-speed calculations. Instead, jump into telemetry and find your RH at speed for the corner you wish to work on. You might use this for straight-line speed too. Note the average RH for the front and rear by adding the RHs together and dividing by two. Accomplish this for the other end of the car then input your findings. After input, raise and lower the values and play with the tool to note how RH changes affect the drag and front DF levels of your car. The practical application for this is to find the single area of the track you need to work on, determine the RHs, and move the wicker, static RHs, or spring/torsion bar settings to achieve drag reduction whilst maintaining front/rear balance. This way, the driver can maintain balance, achieve less drag, and keep the same (or better) level of downforce. See Figure 1.
Figure 1. Aero-Calculator