On the Runway
Most entrepreneurs don't start aerodynamics companies. Sure, the Wright brothers were a notable exception, but these days a young business is much more likely to make a smartphone app than a sweet set of canards.
RHR Performance isn't your average startup, though. We talked to Olaaf Rossi, one half of the team behind the game-changing aerodynamics company. He, alongside A.J. Hartman, is determined to change how people like you and us add downforce to our race cars.
How did they get started? Simple: They met at the track. Back in 2014, Olaaf was running an S197 Mustang in NASA's Spec Mustang class, and he kept running into A.J. Hartman, who was running American Iron. After a few years, Olaaf went to A.J. with a proposal: Co-drive with him in an American Endurance Racing series race.
As Olaaf explains it, "Endurance racing is a pressure cooker, but A.J. and I got along really well." It was then that A.J. shared the details of his newest business, a small company making Mustang wings, called A.J. Hartman Racing. Olaaf had just sold his own company, one that developed custom software, so the opportunity seemed like a match made in heaven. A.J. and Olaaf partnered up and renamed A.J. Hartman Racing as RHR Performance.
Takeoff
A.J. and Olaaf had a company. Now they needed a product. At first, they went with what they knew: Mustangs. They built almost every conceivable carbon-fiber SN95 Mustang part, then started branching out: This year's focuses are the S550 Mustang and C6 Chevrolet Corvette. As Olaaf says, "We try to build parts for cars that people are racing or are going to be racing, especially cars with clear needs that nobody else has addressed." RHR also decides how far to push each platform, from a simple splitter to a complicated Time-Trials aero package that can double the car's weight at speed.
Take the C6 Corvette, for example. RHR identified two primary needs that nobody else had addressed: Canards and a rear wing. Sure, they already made a decent wing–the Fulcrum single element–but they knew a high-horsepower car needed something more. RHR now offers two different sets of canards and a big dual-element wing for the C6, in addition to a spectacularly pretty three-dimensional splitter.
In contrast, RHR knew that the S550-chassis Mustang would be pretty common in the paddock. They designed two full aerodynamics packages for this car—one built to meet American Iron rules, and one built for less restrictive classes that can add more than 1200 lbs. of downforce at 100 mph.
In addition to the aerodynamic elements, RHR offers doors, hoods, decklids, bumpers, and other goodies. Hey—if you had a beautiful carbon-fiber molding facility, wouldn't you make as much as you could, too?
Learning How to Fly
We start most of our own aerodynamic projects with a sheet of plywood, a jigsaw, and a dream. At RHR? Not so much. Take their C6 Corvette canards as an example. RHR started by buying a detailed digital 3D model of the car, then fed it into their CFD (Computational Fluid Dynamics) program and let their aerodynamicist go crazy. After a bunch of digital modeling, they tested five different iterations in the computer, finally settling on what's for sale today. They make two versions, a high-downforce and a low-drag set, with the high-downforce version adding 300 lbs. of downforce at 150 mph. All new parts the company makes come with detailed data—downforce, drag, etc.—so customers can tune their cars and their others aerodynamic aids to work perfectly at each track. The days of cardboard and plywood mock-ups are over.
What about the wind tunnel? As Olaaf tells it, that technology has mostly gone the way of the Wright brothers. No, Google Sketchup can't model air flow, but the professional-level software and hardware that RHR uses (the same stuff F1 teams have access to) is better at simulating and controlling variables than the real wind tunnels that cost $10,000 per hour. Skeptical? So were we, until he shared this data point: Formula 1 teams have a limit on the number of hours of CFD computations they're allowed each season; otherwise, they'd just constantly model every single permutation until they'd melted their computers and drained their bottomless bank accounts.
Is there a downside to the shift from tell-tales to processors? One, Olaaf admits: Figuring out how to make the physical part. The aerodynamicist can come back with a design that takes a 5-axis CNC machine 200 hours to cut a mold for, but carbon-fiber parts with that much upfront cost would be too expensive for everyone except those F1 teams. RHR spends hours translating optimal designs into realistic manufacturing processes, rather than trying to translate realistic manufacturing processes into optimal designs like we do with our plywood splitters and home-molded diffusers.
What About Your Plane?
"This is all great," you're probably thinking, "but what about my particular Civic/Miata/M3/Mustang, and what about my particular wing/splitter/diffuser/canards?"
First, we asked Olaaf when a car is "ready" for aerodynamic development. He gave two answers: As soon as a car goes over 50 mph, but it depends what your rules say, especially if you're in a series where each modification is worth a certain number of points, and it's up to competitors to stay under a limit. He's blunt about a simple fact, though: "Even a Spec Miata could benefit greatly from some aerodynamic elements."
After that, he wanted to hammer home another point: "The details definitely matter." He sees so many people put a big, beautiful wing on the rear of their car, then build a small plywood splitter because they're scared of damaging anything fancier. Then, he says, they end up running the rear wing at a real shallow angle of attack or removing rear mechanical grip to balance the car's handling. Olaaf stresses that aerodynamics is not a wing or a splitter or a spoiler. It's a holistic approach to making a car faster, and the entire car's airflow and handling needs to be a part of every decision. One example of this is the car's center of pressure, where the center of an aerodynamic package's downforce is located. This needs to match the car's center of gravity; otherwise, the car's weight distribution will change with speed, making it unpredictable and harder to drive. RHR keeps all of this in mind, giving these numbers (as well as metrics for ride height, speed, pitch, roll, and yaw) with every aerodynamic element.
Reading the Instruments
How do you figure all this out? Like for every other question, RHR had the answer.
"Another mistake is people not using their data-acquisition systems to look at what their car is doing and why," Olaaf groaned. He sees this pattern at every event: Finish the race, clean the car, download the data, check the brake pads, drink a beer, and load up the trailer. Sure, you may have made a change to your car, but you’re never really analyzing the data to see what it did. At most, Olaaf figures, most racers are just looking at segment times to figure out how fast they went.
"Well, then, what should we do?" we asked. Olaaf casually rolled into his next suggestion as easily as a waiter asking "Would you like dessert with that?"
"The best thing is to build an inverse corner radius math channel that tells you where in the turn you’re turning the most. You can see that and then plot your yaw against that. That answers the question 'Am I understeering or am I oversteering' at each specific point in the turn. Then, see if it’s a high-speed or low-speed turn, and you can tell if you're masking your aerodynamic shortcomings with mechanical changes or vice-versa.”
Basically, aerodynamic aids should increase your minimum speed in a corner (the tightest part of the turn), and increase your maximum lateral deceleration, meaning the car brakes harder.
Want more math? Olaaf also shared the formula you can theoretically use to figure out how quickly a car can take each corner: "The velocity that the car can go around the corner is the square root of the coefficient of friction of the tires multiplied by the weight on the tires plus the 'weight' of downforce, multiplied by the radius of the turn, divided by the mass of the car." Otherwise known as Velocity = Sq. rt of the CF(W+D)*R/M
Different Flying Styles
So, you've done the math, figured out your car's weak spots, and ordered a sweet wing and splitter from RHR Performance. What next?
Everything changes. Olaaf is blunt: "Everything affects everything in a race car." Downforce will mean you'll need stiffer springs and higher tire pressures, as well as a higher static ride height. You'll need better brakes, too, because stopping harder will increase pad temps. You'll use more fuel and tires. You'll need more rear brake bias, because the car will have a higher percentage of weight over the rear wheels. Most importantly, though, you'll go much faster.
These are all well-known effects of adding downforce, but RHR mentioned a big one we hadn't considered: Something they call "raceability" will change, meaning your car will drive very differently. A car that was once only good for passing on the straights could suddenly be a late-braking, dive-bombing champion, and pass on the outside of turns with ease.
Landing
So, what did we learn? We learned a few things.
First, RHR performance is on the cutting-edge of consumer aerodynamics, using tools and processes normally reserved for F1 teams or Boeing to lower our lap times. They do this within real-world constraints and emphasize transparency, meaning anything you buy will be reasonably priced, and they'll help you understand how and why it works.
Second, aerodynamics is worth taking seriously as a part of race prep at any level, and almost any data acquisition platform can be used to optimize your own set-up.
Third, a car with a wing and a splitter will drive differently than one without, and it's important to adjust the rest of your set-up accordingly.
To learn more about RHR Performance, check out their website here.
This story isn't the last you'll hear about RHR Performance. We've already got plans to work with them on a few project cars, and we'll take an even deeper dive into aerodynamics then. Stay tuned.
