Aerodynamics Fundamentals: Example Rules in Series
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Example Rules in Series
05.24
| 00:00 | While aerodynamics behaves by the same fundamental physics from car to car, different series place very different limitations on how you can design aero devices for a car. |
| 00:09 | In this module we'll go through a few example series rules and talk about their consequences. |
| 00:15 | Let's start with World Time Attack Challenge, which has one of the more well -defined aerodynamic rule sets in club level competition. |
| 00:21 | A good example of a rule set that could be exploited can be found in the Club Sprint class. |
| 00:25 | Looking at the aerodynamic regulations, we can see that they state that the splitter may extend 50 millimeters ahead of the bodywork, no further rearwards than the front axle, and no wider than the OEM guards. |
| 00:38 | However, they also make reference to a drawing, and on this drawing we can see that the splitter shape is only required to follow the bodywork until the front of the original coachwork. |
| 00:47 | Then once it comes back behind the front of the coachwork, it's allowed to stay at the forward most point of the front coachwork. |
| 00:54 | This ties in well to the front canards and winglets rule, which states they must not extend forwards of the original coachwork. |
| 01:01 | Prior to 2021 everyone simply followed the bumper with the splitter that was 50 millimeters offset. |
| 01:07 | However, in that year a number of teams saw the loophole and began significantly increasing the size of their splitter at the corners. |
| 01:14 | This wasn't from a change in rules, it was just people paying more attention to the rules, and it yielded very solid increases in front downforce. |
| 01:23 | Looking at the rest of the aero rules here to round this out, it's pretty vanilla for the most part. |
| 01:28 | We can have side skirts that are 250 millimeters wide, a rear wing that's at a certain maximum location and span and have no more than two elements, and lastly a diffuser that's within the bodywork and starts at the rear axle centerline. |
| 01:42 | It's very common in these types of rule sets to not allow any aero between the axles, so that means no flat floors. |
| 01:48 | In these cases it is still typically beneficial to run a rear diffuser to maximize performance. |
| 01:54 | Some regulations, such as Gridlife Touring Cup or GLTC, offer some more unusual approaches to dealing with aerodynamics, such as balancing factors. |
| 02:04 | Essentially, they modify your power to weight ratio depending on what aero devices you have on the car. |
| 02:10 | When it comes to rules like these, in most cases we'll gain the best lap time performance by going bigger on the aero and taking the power here. |
| 02:17 | However, it's all very case specific and we may need to evaluate items on a test day where balance-best lies for our ruleset. |
| 02:25 | In this particular scenario, putting on a single large wing will give us a plus 3% factor, but adding a large wing in a splitter is only 5%. |
| 02:34 | Scaling that down to a medium wing in a splitter is 4%, so we'd always go with the large wing in the splitter, as the extra downforce should easily compensate for the 1 % power-to-weight difference. |
| 02:46 | However, looking in the last row of the balance table, there are some more common OEM items like a Honda S2000C, RR like lip, or factory canards. |
| 02:56 | These items, like most OEM based aero, generally aren't very effective in terms of lap time, so may not justify the 1% power-to-weight disadvantage. |
| 03:05 | We can see here the subtleties in picking what is the correct compromise, and the need for robust testing to determine the fastest package. |
| 03:12 | Some rules categories are very open, like those found in the UK Time Attack series for example. |
| 03:17 | These rules might just have a few short sentences on each rules class to put in the various limits on aero. |
| 03:23 | For example, take a look at this extract from the Pocket Rocket and Club classes. |
| 03:28 | These rules state that we essentially have to have the box for the rear wing defined as 100mm from the top of the roof and 100mm back from the rear bumper. |
| 03:37 | The width of all aero maximums is defined as 100mm from the car below the door mirror, and the front aero must follow the shape of the front bumper. |
| 03:46 | Beyond that, it's all free, so in this ruleset we want to maximize the front splitter out to the full extent of the box as 100mm isn't anything crazy, and then we'll balance it out with a solid dual-element rear wing placed near the limits of the box at the back. |
| 04:00 | One of the more difficult things we'll have to work with is when we have very unrestricted rules, like those found in pro-extreme class. |
| 04:07 | In this case, development is actually much more complex, as we'll have to decide on the correct shape and size for everything. |
| 04:15 | To get the most out of a package like this, we'd ideally hire a professional aerodynamicist for a fully developed aero kit. |
| 04:22 | If that's not in the budget, then the trick is to not go too big and crazy. |
| 04:28 | I wouldn't recommend more than 200mm of forward overhang from a front bumper and 150mm overhang from either side on the front splitter if you're not getting it professionally developed, and then balance that out with a beefy dual-element rear wing. |
| 04:42 | With that covered, let's summarize. |
| 04:44 | Aerodynamics in racing varies greatly across different rulesets, which dictate the design and performance of aero devices. |
| 04:52 | In World Time Attack Challenge, for example, teams have exploited loopholes in splitter design to enhance downforce. |
| 04:59 | Some series, like GLTC, adjust power to weight ratios based on aero devices, making testing crucial for finding the optimal balance between downforce and power. |
| 05:09 | In less-restricted categories, such as the UK Time Attack Series, teams have more freedom, but the challenge lies in finding the right aero design without going overboard, especially without professional help. |
