How Driver Height Affects Karting Aerodynamics

How Driver Height Affects Karting Aerodynamics

Karting is unique in many ways, but one of the most important differences compared to the cars is the open cockpit. In other words, the driver directly faces the incoming airflow – there is no windshield nor bodywork to hide behind it. The driver is fully exposed to the air and acts like an active aerodynamic device. Does the driver height really affect kart performance, and if so, how much?

3D modelled karts with a tall and a short driver in aerodynamic simulation environment

To answer this properly, we compared two extreme cases:

2.0 m tall driver
and 1.6 m tall driver.

Both drivers were analyzed in the exactly same kart, allowing us to legitemately compare results.

1. Difference in Airflow

Behind the taller driver, a much larger wake forms.
This happens because a taller driver presents a larger frontal area to the airflow, disturbing and slowing down more air.

A larger wake creates a stronger low-pressure region behind the driver. 2D pressure visual indicated larger blue area behind taller driver, and that low pressure effectively pulls the kart backward. The result is increased drag and reduced straight-line performance.

Comparison of a short and a tall driver simulated in a windtunnel — The tall driver creates a much bigger low pressure area behind the kart, which effectively pulls him back.

2. Drag of a Tall Driver

The taller driver experiences significantly higher pressure buildup on both the chest and the helmet.

The taller driver is forced into a more compact position, with bent and raised knees. This creates additional high-pressure zones.

Short and tall driver comparison of wind hitting the upper body — The upper body of the tall driver stop more air and builds significantly more drag as it stands higher.

3. Drag of a Short Driver

The shorter driver sits lower and a smaller portion of their body gets hit with airflow, generating less drag.

The 160 cm driver can also keep his legs relatively relaxed, allowing airflow to pass more cleanly through the cockpit area.

The knees of the short driver don’t generate any drag as the fit below the nassau panel.

Each of these pressure concentrations adds resistance — and all of that resistance directly translates into higher aerodynamic drag.

4. Slipstream

A taller driver does more “work” on the straights by disturbing more air. As a result, the following kart benefits from a stronger tow and a bigger speed advantage.

On the other hand, the shorter driver leaves behind a cleaner airflow wihout affecting it much, which actually makes the slipstream behind him less effective.

Conclusion

Shorter driver achieved: Drag coefficient (Cd): 0.54 and Lift coefficient (Cl): -0.14. Taller driver achieved: Drag coefficient (Cd): 0.59 and Lift coefficient (Cl): -0.17. See previous blogs for reference.

The short driver generates less drag with fewer obsticles. Meanwhile the tall driver gains extra downforce that can improve outright grip levels.

Shorter drivers benefit from reduced drag and better straight-line efficiency. Taller drivers generate more downforce, which improves stability but increases drag at the same.

Oskar explains the differences further in the video. Follow him on YouTube!