How do you build a car with twice the power of a modern F1 car, lighter weight, and with much more downforce than even the Group C le-mans ground effect monsters? Lets take a look at the ElmerRacing er8!
Here at ElmerRacing we're no strangers to crazy ideas, and designing and building racing parts that outperform everything else. Since we already produce the worlds highest power-to-mass ratio circuit racing engine, the 2000hp* 150kg "Thor", it's hardly surprising that the target for the er8 is the be the worlds fastest race car!
Well that's all good. But how do you actually make something like that without the factory Group C and F1 teams budget of 100M€+, wind tunnel testing, etc? Step one is to get rid of as many design restrictions as possible that especially F1 have to comply with. Once we're done with that:
|F1 2023||Group C
|Downforce||ClA: >>9||?||ClA: 8.174|
We already have the engine, so that part is easy. More power and lower mass than F1 and group C engines. Perfect. You can even buy your own Thor engine directly from our webshop!
Super low mass? Well the engines helps a lot here, but achieving a sub-800kg race weight while keeping to a reasonable budget is still not easy! A full custom chassis would definitely make this much easier. However, since we want to be able to race the car also, we need to comply with the technical regulations of some race class. In our case the most interesting category is the technical playground of TimeAttack! We need to build off of a existing series produced non-supercar chassis. The leading criteria for that would be 4wd, as small and light as possible, and as small frontal area and as aerodynamic as possible, with cars available at a reasonably low cost. The best possible car we could find was the 1969 Opel GT. 4wd unfortunately had to go, but otherwise the chassis fits the criteria very well.
The best and lightest part is of course no part. We will for instance be running no clutch (or torque converter) at all in the car. Direct driveshaft from the front-mid engine to the rear-mid gearbox. Some other innovations allow significant weight savings compared to a "typical" car of this type. If there is such a thing.
We are expecting the er8 to be significantly over our target mass at its first event due to running several oversized components though. On the plus side, components like the diff should hold up extremely well, being capable of much more load than needed for this car!
Well this is where carrying as little baggage as possible helps a lot. If you compare to "no regulation" cars like the aston martin valkyrie, red bull concept cars etc. you will see how detrimental it can be to have F1 aero guys working on the design. You actually want the maximum amount of surface area possible on the floor of the car, with highly tuned ground effect to get maximum downforce. Not big openings, front wings, barge boards, etc. To get space for the ground effect tunnels underneath the car, we have raise up and angled the chassis forward (compared to if it was just placed as low as possible).
Ride height and pitch sensitivity are important for performance. If you have a super sensitive aero package and need to keep your rideheight within a very narrow range to work well, you're going to have a hard time setting up the car, and have to run a very stiff suspension that creates big shock loads through the car (and driver!) over bumps. This is what our ride height and pitch sensitivity looks like at the moment (ride position in relation to CAD draw height).
As to not frighten event organizers, regulatory bodies, and insurance companies, we'll for the time being just say that the downforce numbers we have are somewhat above Group C cars. Drag is significantly higher due to us using a road car chassis as a base point, and not having very much rear overhang to utilize. But with the huge engine power we have available, drag is really a non-issue. Due to being limited on tire size with World Time Attack 2023 (targeted first race) -Pro class rules, we will need to run a much lower top speed than what the Group C cars can anyway. The issue here is increasing speed increases downforce, and this will at some point become too much for the small diameter tires. With active ride height control, or active suspension, this could be circumvented by either running extremely low or high ride height at higher speeds to reduce downforce. This would add drag, which we aren't overly concerned with, but more importantly would not be very safe.
Safety is a mayor concern with this build. Just take a quick search on youtube for "lemans flying cars" to see what can easily happen. We have spent the last 1-2 months not increasing downforce, but tuning aerodynamic pitch and more importantly yaw stability. Check out cfd result examples in the plots attached to this article!
Failures are to be avoided at all cost. But there also has to be fault tolerance, since things can and will go wrong. Hitting debris on the track etc. it's very possible to end up jumping the car and landing with a 50deg yaw angle for instance. What will happen in that case? With most cars, the situation would be unrecoverable. With our er8 we think we have a stable enough aero setup for that type of a situation to be recoverable. Having the center of gravity as far forward as feasible helps, we will be close to 50:50, and having as much aerodynamic cross section at the rear of the car also helps. Full cfd needs to be run at varying yaw angles of course to fine tune the design. Both the front:rear downforce and "sideforce" distribution (yaw torque) need to be analyzed. A lot of work, that we hopefully never need to test on track. But at this performance level it needs to be taken seriously.
Spec & Performance
The main factors for race car performance are downforce/mass ratio, and power/mass ratio. With some very high speed circuits also needing high power/drag ratio.
Lets just say that we expect to be able to set the absolute lap record on every track we race at. The er8 is designed for larger tires than what we are allowed to run at the World Time Attack event. So at other events we can run higher top speeds and be competitive on circuits with long straights also.
Unless someone buys the car from us before we have the chance to race it ourselves of course!