“One test is worth 1,000 expert opinions.”
Werner von Braun
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Speed costs money…so how fast do you want to go?
It’s an age-old question.
One of the great things about racing is there is a class for any budget. At Summit Racing, we love CHEAP SPEED—but what do you do when you’ve hit a horsepower wall?
The A2 Wind Tunnel is a magical place where you can add 5, 10, or even 25 mph to your top speed in a single day without adding a single horsepower.
At a few hundred bucks an hour though, it’s not exactly cheap. But cranking through 30 aero configurations in an eight hour day is possible. It can also SAVE money because lower aero loads don’t stress the engine and drivetrain as much.
Aero is a gift that keeps on giving—plus, it’s just plain cool…
In the tunnel, you will find answers to your questions.
Then start asking more questions….
What Is Wind Tunnel Testing?
The A2 tunnel is one of two in Mooresville, NC. Built in 2002, it’s 14 feet wide, 10 feet tall, and 58 feet long and has measured anything from bicycles to karts, motorcycles, muscle cars, sports cars, race cars (of every type), and in our case TRUCKS!
How does it work? Four large fans installed at one end of the tunnel pull air over, under and around a vehicle at speeds up to 85 mph. The floor has precision scales to measure weights at the four corners. This produces data on Lift/Downforce, Drag, Side-Force, Yaw, Pitch, and Roll. It also has 16 pressure transducers that can be run to various areas of the bodywork.
Who needs this kind of data? Anyone looking for a competitive edge!
The Wind Tunnel Experience
In our case, we were testing with Rick Lind. Rick has a C10 Chevy truck body affixed to a NASCAR truck chassis with an 830 hp Dodge R5 engine. It’s gone 194 Mph at the ECTA Standing Mile in Blytheville, Arkansas. It’s in the 11 minute zone at the Pikes Peak Hill climb and sees many track days (Barber/VIR/etc.).
As wild as that sounds, what is going on behind it is even wilder.
Neil Campbell is a Bicycle Racer…one that has PEDALED at 174mph. The plan is for Neil to ride in the wake of Rick’s truck and hit 200.
All of this is going down at the ECTA Horsepower Harvest held in Blytheville, Arkansas Oct. 3 2025!
The 200 mph attempt will be the culmination of a 10-year mission to be the fastest slipstream cyclist in the world. Within that time Campbell has developed an array of aerodynamic fairings which have evolved to be used with incrementally more powerful pace vehicles, guided only by experience and basic aero modelling.
The difficulty of the venture is allowing the pace car to achieve its top speed when the fairing creates such tremendous drag. There is always a compromise between vehicle speed, stability, and the volatile turbulence within the slipstream for the rider.
It’s a full-on science experiment.
This was his first time in a wind tunnel, which was a revelation because it demonstrated in real time that the vehicle has the power required to achieve the target speed, while ensuring vehicle stability and providing enough shelter for the rider.
Wind Tunnel Testing Methodology
Before we see the data, let’s talk about the general goals and methods used in a wind tunnel. The overall goal with speed is to disturb the air as little as possible. We are trying to return the air back to where it was originally.
With drag, the shape at the back of the car is often more important than the front. We can’t drive teardrops, so the next best thing is to keep air attached to the body until the rear bumper. Seven to 14 degrees of taper (called the angle of divergence) keeps air adhering to the bodywork and prevents drag-inducing vortices. Around 14 degrees, vortices occur, and this is the drag (vacuum) that’s literally tugging you backwards.
The second thing to know with Aero: Preconceptions are often wrong and can even be dangerous. Very small and seeming unrelated changes can have large effects (and often on the completely opposite side of the car). These are things that can’t be found on the track. The A2 tunnel allows a team to test multiple configurations over the course of your session.
Wind Tunnel Aerodynamic Bodywork Testing Tips
The bodywork doesn’t have to be pretty or even permanent, but it needs to be modular. Having your fabrication done prior with quickly adjustable bracketry on movable panels (wood, foam, sheet metal) allows you to test multiple configurations quickly.
Here are some common aero tools and areas of improvement:
- Vents are normally placed in the hood to relieve under hood pressure buildup that causes lift. Placement is critical. The windshield has a high-pressure zone at the base, so we avoid placing hood vents on the back half of the hood. Overall drag generally goes up with hood venting, but preventing lift is the overall goal.
- Grilles should be open just enough to control heat. Any larger and they create a high-pressure zone under the hood that causes lift. Testing with tape in the tunnel and having it available at the track produces the best balance.
- The Cowl (at the base of the windshield) isn’t easily modified but reduces drag. We create a gentle slope from the hood to the otherwise steep windshield.
- Splitters and Air Dams: Over 25% of the air must pass underneath the bumpy and drag-inducing floor. Modern cars are smooth underneath which decreases drag AND lift. Air Dams reduce front lift by preventing air from going underneath and packing under the hood. Extending a splitter farther out helps keep positive pressure on top and going around. Different sanctioning bodies limit how far they can extend. Keep in mind, increasing downforce in the front can increase lift in the rear (and vice versa). Loads cantilever off the axles.
- Side Skirts: These can help OR hurt. The goal is to keep side air from rolling under the floor from the sides and creating lift. The problem is the wake at the rear (negative pressure) can cause air to curl and pack underneath into this new-found low-pressure zone and cause net lift. Wind Tunnel testing is the only way to ensure skirts are helping rather than creating a dangerous situation.
- Wings and Spoilers. Moving the wing’s Angle of Attack gives the team the right balance of drag and downforce. Drag Spoilers extend the car’s length artificially and move the wake farther behind the bumper. If downforce is the goal, it can be angled up to reduce the low-pressure zone on the trunk lid that produces lift. Sometimes spoiler shapes are combined for reduction in drag and lift, but in general they are less efficient than wings at reducing lift.
What Tools to Bring to a Wind Tunnel Test
A2 has a good list of tools you need—but bring 10 rolls of tape and maybe some yarn.
The Smoke testing does help visualize flow and turbulence, but yarn can tell us which direction flow is basically going. You will also want to bring raw sheet materials and fasteners to make modifications and extensions (wickers, Gurney’s, flaps, etc.). At the end of the day, time spent in the tunnel provides you with assurances you are going in the right direction.
Let the Testing Begin!
Now to the techy stuff you came here for! This is a baseline created off Rick’s last “as-raced” configuration.:
- Lift on the front: -0.284 = 922.6 lbs. Downforce (The Splitter plants the front end, and stronger springs are required to compensate).
- Lift on the rear: 0.011 = 34.3 lbs. of Lift (not terrible with its tonneau cover).
- Net overall lift: -0.273 = 888.3 lbs. of Downforce overall.
- Frontal area: 28.6 sq./ft.
- cD (coefficient of drag): 0.416
- Horsepower to maintain 200 mph: 721.2 hp (this doesn’t include mechanical losses or the power required to get up to this speed).
- Drag (lbs. pulling rearward): 1,352.2 lbs.
- L/D (lift/drag ratio): -0.66
Next up, the grill was taped up for drag reduction. Bracing was added to the rear quarter and back deck panels for stability. Rear wing angle was increased to offset the downforce created at the front.
Results of Test 3:
- Lift on the front: -0.316 = 1,027.4 lbs. Downforce
- Lift on the rear: 0.023 = 75.8 lbs. Lift
- Net overall lift: -0.292 = 951.6 lbs. Downforce
- Frontal area: 28.6 sq./ft.
- cD (coefficient of drag): 0.400
- Horsepower to maintain 200 mph: 694.2 hp (Note what a little tape can do!)
- Drag (lbs. pulling rearward): 1,301.6 lbs.
- L/D (lift/drag ratio): -0.73
We succeeded in reducing drag, increasing downforce in the front, but added a little lift in the rear. Horsepower requirements dropped by about 27 to maintain a speed of 200 mph!
Next up, we installed the Topper and the fairing panels. A NACA-shaped lower diverter was installed behind the rear axle to keep air off the rider’s front tire. It’s important to remember the truck has plenty of horsepower. The goal is to keep the wind off the rider at all expense. Stability at speed is more important because the rider is in the wake.
Results of Test 5:
- Lift on the front: -0.356 = 1,158.7 lbs. Downforce
- Lift on the rear: 0.147 = 477.4 lbs. Lift (big increase!)
- Net overall lift: -0.209 = 681.3 lbs. Downforce
- Frontal area: 31.8 sq./ft. (The topper was a little taller and the diverter below added area even though it was behind the air dam.)
- cD (coefficient of drag): .415
- Horsepower to maintain 200 mph: 720.2 hp
- Drag (lbs. pulling rearward): 1,350.3 lbs.
- L/D (lift/drag ratio): -0.50
The Topper, fairings, and air diverter added behind the rear axle increased downforce on the front but created a much greater (and feel-able) increase in rear lift. Without the diverter installed underneath, the results would have been different, but the whole package was tested as one.
Next up, the diverter skirts were shaped differently and strengthened to maintain its shape against the wind. The fairing angles were changed several times. A Gurney lip was added to the top fairing as well. A little increase in drag was acceptable to keep rear lift in check for added stability overall.
Results of Test 15:
- Lift on the front: -0.318 = 1033.5 lbs. Downforce
- Lift on the rear: 0.072 = 233.1 lbs. Lift (acceptable trade with drag reduction)
- Net overall lift: -0.246 = 800 lbs. Downforce
- Frontal area: 31.8 sq./ft.
- cD (Coefficient of drag): 0.425
- Horsepower to maintain 200mph : 737.5 hp
- Drag (lbs. pulling rearward) 1382.7 lbs.
- L/D (lift/drag ratio): -0.58
Between the initial baseline and final configuration required for shielding the rider.
- Front Downforce increased from -0.284 to -.0318 (922 to 1,033 lbs.)
- Rear Lift went from 0.011 to 0.072 (34 to 233 lbs.)
- Overall downforce dropped from -0.273 to -0.246 (888 to 800 lbs.)
- cD went from 0.416 to 0.425 (Note: This doesn’t include the additional frontal area of 3.2 sq./ft.)
- Horsepower required to do 200 went from 721 to 737
- Drag went from 1,352 to 1,382 lbs.
Finally, the bike and Neil Cambell were in place. The goal was to ensure he had a nice bubble of calm smooth air to ride in. No unexpected gusts that could knock him off his bike at high speed.
The final test results all reflect Neil in tow.
Results of Test 16:
- Lift on the front: -0.314 = 1,022.1 lbs. Downforce
- Lift on the rear: 0.063 = 206.1 lbs. Lift
- Net overall lift: -0.251 = 816.0 lbs. Downforce.
- Frontal area: 31.8 sq/ft.
- cD (Coefficient of drag): 0.432
- Horsepower to maintain 200 mph: 749.9 hp
- Drag (lbs. pulling rearward): 1,406 lbs.
- L/D (lift/drag ratio): -0.58
Check out the smoke to visualize how the low-pressure envelope extends behind the rider.
When you are ready to make the dream trip of a lifetime, A2 has an excellent FAQ on what you need to be prepared.
Want More?
For higher level racing like NASCAR, the 130 mph Aerodyn tunnel next door has 22 fans, plus a rolling road to replicate the wheels in rotation and removes the boundary layer.
264 static pressure sensors in the floor help engineers visualize the entire underside of the car. Some other cool features include automated Right Height and Yaw measurement changes. Still not enough data?
When you are done in the tunnel, you can head to Centroid for Center of Gravity and Polar Moment of Inertia measurement!
Special Thanks
Special thanks to Rick Lind (Race Truck owner), Michelle Herron, Cody and Alicia Jenkins (Media), David Salazar (Aero), Tim Clements (Fabricator extraordinaire), along with Geoff Eaker and the A2 crew!
Richard Tomlin is Apex Auto Works out of Houston but is really just a kid chasing the dream! Plays with Mopars to Miatas, heck, even Odyssey manual swaps—yes, he does that. Autocross, Road Race, Tarmac Rally Mexico, Pikes Peak International Hill Climb. Go check his builds out on FB, IG and ApexAutoWorksTx.com.
Steve Strupp is with the East Coast Timing Association. The next of his Arkansas Mile events is the 8th Annual Horsepower Harvest Oct. 3-5, 2025. This event is held in Blytheville, Arkansas but other ECTA events are held in North Carolina and Bonneville. There’s a class for everyone—it’s well organized and a great safe place for people to experience more speed!
We look forward to seeing your team hit your goal of 200mph!
…And remember, a bad day in the Wind Tunnel is better than a good day in the Office!
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