When it comes to all the various forms of motorsports, aerodynamics is a topic of constant debate. That is, until you get to drifting. To spark some talk before the 2018 Formula DRIFT Season starts — and maybe even more debate — we asked experts, drivers, and Formula D's Technical Director about downforce producing devices in the art of going sideways.
First, let's define what we're talking about here specifically — downforce. You go into any technical book to try and look up the term "downforce" and you'll quickly find it doesn't exist; however, we hear the term tossed around like stickers at the Baja 1000. While it's accepted to say it to make things easier for the layman, the term you're looking for is "lift." And on the face of it, saying lift seems counterintuitive from what you're trying to achieve.
However, no wing produces downforce, as all wings create positive (the upward motion a wing creates to get you into the air) or negative (the downward motion a wing creates when you need to dive) lift. Measuring lift is relative to the wing itself, so that's why you can have negative and positive lift. Even though the vehicle is on the ground, it's still negative lift that is being utilized to put additional pressure on to the chassis and tires to keep it planted to the surface. So, what we call "downforce" is technically "negative lift;" it's just easier to think of it as downforce. You're also not wrong for calling it that — just don't expect technical books to use the term.
MORE THAN JUST LIFT
There is more to aerodynamics than lift, though, when it comes to street and race cars. We must think about the inlets and outlets to allow air to pass through the body for cooling. We also must take air flow into consideration around the body of the vehicle itself to prevent wing stalling — a condition where the air no longer creates lift because too much air has separated from the low-pressure side of the wing (potentially deadly in flight and can be equally harmful in race cars at high speeds). The low-pressure side is the side where air flows over quickly, so it's top of the wing on aircraft while it's the underside of the wing on cars. When you get into a stall, the wing also begins to create drag because it's now acting more like a parachute than an airfoil, to simplify it.
Wings that need to create lift generally have about eight to 20 degrees of angle before the flow separation is too great. Racecar wings can generally get away with more before drag becomes a problem, usually not more than 24-degrees of angle. They can also increase the angle of attack by using multiple flaps on a wing to reduce the penalty of drag — that's the real reason we see multi-element wings on race cars. However, stalling a wing does have benefits if you do it right. Racecars can create wing stall with little drag to generate more speed in a straightaway by changing the angle of attack (instantly changing the wing's angle to the air like Formula One does now). Engineers have even found creative ways to redirect air from the body of the vehicle to create a stall without, or very nearly without, the penalty of drag — like the F-Duct by McLaren or the blown diffuser from Red Bull in Formula One racing.
MORE THAN RACE CARS, TOO
There is a competition train of thought and a road-going one for the engine, and the same can be said for aerodynamics. Thinking about how the air flows around your vehicle is critical to automotive manufacturers. The more we need to save gas, the more those engineers must find gains by reducing the strain an engine goes through to push the air around itself. While a Civic Type R has interesting aerodynamics to make it more competitive, Honda engineers had to also find ways to make it flow through the air.
That air scoop on the hood cools the engine (well, not a lot), but it also creates a path for air to flow out of the engine bay and out of the body without putting a much bigger hole in the hood like an Evo employs. A flat bottom car creates less drag, so cars like the Toyota Prius use it to make it more efficient while driving at highway speeds. Those oval-shaped tailgate tops you see on trucks like the Nissan Titan, it's all to give air flow off the cab's roofline a place to flow to and reduce drag. Even functional diffusers on OE-body cars like the Subaru WRX are made to enhance flow off the trunk and slip through the air better.
A lot of those items sound like racecar technology and some of it does trickle down from motorsports. However, to blatantly say the flat bottom under trays, wings, and ducts are all thanks to racing technology wouldn't be entirely truthful. Even the parts we take for granted in racing aren't solely from the racing world. Most of those items, for both racecars and OEM cars, are thanks to airplane engineers that adapted their ideas to cars, too. So, modern aerodynamics on your car or for your racecar come from a variety of sources and not just the world of competition.
AERO IN DRIFTING
Now all of that's out of the way, we can get back to the point of this article. How does aerodynamics play a role in drifting? Well, currently, not much. Actually, let's rephrase that answer — cars designed to go drifting don't really approach aerodynamics in the way time attack or wheel-to-wheel drivers do. However, going sideways and making downforce is something of an interest to aerodynamics experts like Andrew Brilliant of AMB Aero. Those of you in the time attack world probably know that name well, but for you drift guys, Andrew is the guy who people like Under Suzuki and HKS approach when they need to set new records at Tsukuba, Fuji Speedway, or at the World Time Attack Challenge.
"From our point of view this is a fascinating topic since we now have an array of technologies that can do anything in terms of aero in yaw," says Andrew. "Aero in yaw" is basically reference in air flow as the car starts going perpendicular to its forward motion, if you didn't understand that. "For example, if you wanted the car to have front downforce in yaw, or less front and more rear in yaw, or even to only have downforce in yaw but none in a straight line or vice versa; we could make it do any of those things." A lot of what he's discussing has come from Formula One and Prototype Endurance Car Racing and the rear spine you see running down those engine covers. Turns out, some downforce can be found if you stick a shark fin — like the one pictured below on the back of the time attack PZ Tuning RSX — on the center of the car and drive it around a corner. Air is still trying to go in a forward motion, but the car is at an angle, so the shark fin acts like a wing. That's over simplifying it, by a lot, as the shark find does more than that but hopefully it helps visualize the point.
Ok, so not a lot of drifting is "high-speed" like you see in traditional road race cars, save for a place like Road Atlanta. Even then, you start with a lot of speed and lose a lot of it by the time you finish the course. Drifting is about looking cool, not going fast, but speed isn't as a determining factor as you'd think. Andrew points towards hill climb cars, "Low speed is nothing for us; take a look at hill climb cars: high yaw, low speed, and monster aero." You see this in autocross, too, big wings for cars that drive less than 60-MPH in a parking lot. He also points out, "Our current top time attack cars at 100-MPH are carrying more downforce that the weight of the car." Not 140, not 120, not even at 105-MPH, those cars are theoretically making enough downforce to allow it to stick to the roof at just 100-MPH. That's mind blowing to think about.
DO DRIVERS REALLY FEEL IT?
We asked questions to Matt Field, popular driver known for his extreme looking end plates, and Chris Forsberg, the three-time Formula DRIFT Champion, about their thoughts on aerodynamics in drifting. What was interesting was their responses to wings and splitters. When we generally asked about the difference in the cars with and without aerodynamic elements, they had two different responses to the same two areas. "Yes, I feel the difference in a car with and without a rear wing," said Matt, "Front aero, not so much, but the rear wing does a ton." However, Chris Forsberg stated, "I actually do run a front splitter from APR Performance. This helps push the nose of the car down to maintain front grip as we drift at high speeds with a lot of throttle. We tried the big wing a few times over the years and I feel that it usually hurts us at high speed tracks versus helping with grip."
It was very strange until we asked a car chief. We turned to Mike Kojima, Daijiro Yoshihara's car chief that includes a FD championship in 2011, for a possible explanation.
"Wings don't have much effect except at Road Atlanta," Mike began, "The splitter does in some courses, mostly Seattle and Irwindale. If you look at the tire smoke patterns of cars with wings, you can see that they are not even working due to improper orientation with the airflow and there is tons of flow separation. Basically, the wing is in stall and just making drag." Goes back to our explanation on "downforce" and stall earlier, except that instead of separation because of too much angle of attack, it's separation due to improper airflow — the air isn't flowing straight over the wing but at an angle. Why does that happen? Mike added to that, "Wings (in drifting) mostly do not act like a Bernoulli downforce creating device (Editor: wing in negative lift) but a Newtonian drag-inducing device that provides stability by moving the center of pressure rearward. To me, this has limited usefulness in drifting as it hampers creating angle."
So that's why Matt and Chris feel different affects with splitters and wings but are possibly for the exact same reason. While the wing doesn't generate downforce, it does create a downward pressure from the air mass collecting at the wing. It's not generating lift at all, so it's not acting like a wing but more like a spoiler on a NASCAR stock car (like the one pictured above). The best way to visualize this is to think of it as aerodynamic weight shifting (you're not really shifting the vehicle's weight, just visualize that to get the idea). Matt's use of the wing allows drag to push down on the rear tires at the detriment of the splitter's effectiveness because it's now being lifted and allowing air to flow under it instead of over it. Chris' use of a splitter is maximized better because there isn't a wing trying to shift weight to the rear of the car and keeps the splitter level with the ground.
FORMULA DRIFT'S TAKE
As we know, teams will do what they can to gain an advantage over their fellow competitors. So it's the job of a sanctioning body and their technical director to make sure the field is as level as possible. That job for Formula D lays at the feet of Technical Director Kevin Wells. For the 2018 rulebook, one thing stood out: the limitation on wing standoffs and where they can be used. Was this for aerodynamics? No. "My main concern in regards to aerodynamics is safety," said Kevin, "On the tracks we run aerodynamic devices, such as GT wings, pose a safety risk due to their close proximity to walls and fencing. In the past we have had GT wings come off and hit the vehicle and drivers of the following car. We have had some wings rip down signage and damage the frame supporting them which causes delays in the event. The above are the main reasons why in 2018 we changed the rules and do not allow GT wings or wings on standoffs at the majority of our events."
However, that's not to say he doesn't recognize the efforts of some to try and play with aerodynamic elements on their cars. He recalls a time when Chelsea DeNofa didn't run an airfoil but kept the wing endplates. "One interesting experiment that comes to mind was done by Chelsea DeNofa a few years back who ran wing end plates with no wing in between. Which I assume was to add side force without adding downforce in the high-speed sections of the course. I like that type of creative thinking."
He also recognizes there could be some usefulness to maximizing aerodynamics in drifting, too. "I think aero can be a useful tool in drifting, but it is all about compromise." He gave us a couple of examples, "Our courses have high- and low-speed sections. Can you add aero grip in the high-speed section without having to reduce mechanical grip? If not, then you are probably losing overall in the lower speed sections. If you happen to knock the wing off in tandem, how much does this affect the balance of the car? How will your next run be without it? I believe the above questions regarding vehicle stability and constancy have led to the reduced usage of the GT-style wings of years past in the PRO class."
THE FUTURE OF AERO AND DRIFTING
What do our respondents think of the future of aerodynamics in drifting? Well, Andrew Brilliant is ready for the aero future in drifting. Andrew responded, "Absolutely, it seems like a fascinating sport aerodynamically and a lot of fun to develop for something so unique!" Mike Kojima, however, feels that drifting and aero probably won't be something to worry about like road racing cars do. He says, "Aero is limited in effectiveness because we can't do moveable aero to line it up with the airflow." Much like Kevin Wells, he's also afraid of fan and driver safety, "I am mostly concerned that a wing or parts of one could end up in the stands where it could injure spectators or media. FD's tether rule helps eliminate that possibility and is a good thing."
The drivers are mixed about aerodynamic drift cars, as Matt Field pointed out, "I do see aero coming more into play as the sport develops. FD rules might try to keep that away, but there is some advantage to be gained on tires with a lack of side bite." However, he also points out, "I always like to run big side plates and vertical aero to help improve the side bite. However, with the development of tires, we might not see the need for aero." Chris Forsberg, though, pointed out, "I feel that aero has its place for stability when it comes to any form of racing. However, we need to be cautious with how we apply it as we typically need the opposite of what aero typically provides — less downforce over the rear at higher speeds."
He also has a concern with safety, but not from parts flying away, "My only concern with aerodynamics and the future of the sport is that someone may try to use it to loosen the car at high speeds causing a potentially dangerous situation." This is a reference to a high-speed stall without drag to change the pressure back to the rear of the car, something that could happen and potentially cause a snap oversteer like we see in stock car racing on aero-dependent tracks.
Kevin Wells, however, thinks that teams will eventually take advantage of aerodynamics, "Teams will always strive for every advantage possible and I think aerodynamics in drifting can be an advantage, but finding the overall balance and constancy with our diverse track configurations will be the main challenge." That's also a sentiment shared, in a way, by Mike Kojima, "Our splitter is far from optimized, in my opinion, it is only about 20 percent effective over what it could be. We don't do an elaborate optimized splitter because it is so prone to damage and the nature of the diagonal airflow limits its potential effectiveness anyway."
Will we ever see an aerodynamically optimized drift car? The way things are looking now, possibly not. The root of the problem is the unique nature of drifting itself. The car is purposefully driven in an extreme yaw angle with tires that only just keep some grip to keep the car going in a forward motion. While it's theoretically possible to be able to generate downforce at the speeds and angles these cars see, practically speaking it's not something that's a concern and is just another part to break and stop working at the wrong moment.
Doesn't mean we won't see it and we've already had teams get creative from Chelsea DeNofa's end plate-only experiment to Rhys Millen's GTO with Lexan plates coming off the wing standoffs. Once teams find that maximizing the mechanical grip of the chassis has finally hit diminishing returns, aerodynamics will begin to play a role. However, as tire and damper technology continues to progress, that might be several years down the line. To say the aero drift car isn't coming is foolish, but to say we'll see it tomorrow is just as foolish.
Additional imagery from Toyota and Andrew Brilliant's Facebook page