Wind tunnels and tyres: load cells in automotive testing

Published On: April 19 2022

As the world moves towards electric vehicles, it’s interesting to see innovations that aim to make testing cars and component parts easier and more comprehensive.

It’s a wind tunnel, but not as we know it

Costing a cool $124million, the world’s most advanced wind tunnel tests cars for both aerodynamics and aeroacoustics.

Honda’s new rolling road wind tunnel in Ohio uses a rig whereby vehicles have their brakes and suspension disconnected. The vehicle is them mounted on load cells to keep it at a constant ride height. (For us load cells geeks, the balance (scale) that measures aerodynamic load features a 3-axis load cell in the tower with a Drag Force Sensitivity = +/- 2.5 Newtons (2.5 N).)

Riding high

An article in Design News reveals, for racecars, the ability to adjust the ride height is crucial.

“Race cars’ sensitivity to underbody ground effect means that Honda engineers need to be able to test cars at various heights to understand the effect of raising or lowering the car. Having a ride height system built into HALO lets engineers change those settings and test the results quickly.”

As HALO (Honda Automotive Laboratories of Ohio) wind tunnel lead Mike Unger explains;

“This allows us to not only change the suspension very quickly and precisely from inside the control room, but it also allows us to study the varying ride height as it relates to aerodynamics.”

Fanning innovation

According to an article in ARS Technica, Honda’s new HALO facility features a 8 metres fan to blast winds down the 200+m jet tunnel. As the article explains:

“Road car aerodynamics are now becoming more important than ever as automakers electrify, since even small reductions in drag mean a boost in efficiency.”

However, it’s not just about a streamlined shape. Electric engines are quiet – very quiet. Without the noise of the internal combustion engine powertrain, it’s also about reducing the noise the car itself creates in the wind. To measure this,

“The test car is surrounded microphones—a total of 502 directional microphones arranged in acoustic arrays, with another 54 microphones placed inside the car. These microphones can tell engineers exactly which bit of the car needs a subtle tweak to quiet things down.”

That’s a lot of microphones!

For tech specs of the tunnel, photos and a facility tour video, see Honda’s press release page.

Getting a grip

One of the most impressive parts of Formula 1 racing are the lightening-fast pitstop tyre (tire) changes. Needless to say, there’s no point in swapping tyres out if you haven’t properly tested the ones going on the car mid-race.

As Erich Baumgärtner, CEO of BWR Motorsports, explained in an article for PMW magazine:

“With tires playing such an essential role in motorsport, efficient and quick analysis is very important as production and storage cause substantial tolerances within a batch of tires.”

Fed up with having to take a chunk out of a tyre to analyse it, BWR Motorsports have developed a trackside tyre testing unit. In addition to testing sinusoidal strain on the tread, the unit features:

“A rotary motor and measuring head torque sensor, a linear drive to apply preload and load cells to measure wheel weight.”

Looking for load cells for your vehicle testing?

Call us. We’ve supplied load cells for a wide variety of automotive projects, including a car entered into the Yokohama World Time Attack Challenge.

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