Why most cars have slanted windshields, but trucks keep the windshield straight – Jalopnik

If you’ve been behind the wheel of a variety of cars, from compact sedans and crossovers to pickups and SUVs, you can probably attest to the vast differences in driving experience between the two. One thing you may have noticed is that many cars have a windshield that is aggressively angled. Although in some cases it is completely absent, such as the Mercedes-AMG PureSpeed ​​which ditches the windshield for a lot of cool points. However, larger vehicles, such as big rigs or Class A RVs, typically have a windshield that is nearly vertical. This is not just a design choice, but rather a matter of safety.

Visual distortion through the glass becomes much more apparent when the windshield is angled, and is also more prominent the larger the windshield is. Cars can get away at an angle because the windshields are much smaller. A semi-truck, on the other hand, uses a larger piece of glass, so visual anomalies (which can give a wavy appearance) can become a safety issue. Not only can these distortions be disorienting, but they can also affect things like depth perception, which is critical in any driving scenario, but especially in a vehicle that can weigh up to 35,000 kg.

However, cars do benefit from the aerodynamic improvement achieved by sloping windshields. The engine always works against the resistance of the air as it propels a vehicle. Automotive engineers have been conducting wind tunnel testing since the late 1920s and early 1930s. You can see this by comparing the shape differences between something like the Ford Model T, with its sharply angular design, and the visibly sleeker 1934 Ford Model 40 Special Speedster. These tests accurately show how flowing air interacts with the car’s body, allowing changes that reduce drag, reduce engine stress and improve efficiency.

Okay, but shouldn’t semi-finals also want to be more aerodynamic? Yes, but not at the expense of visibility. Many large rigs have additional features designed to reduce drag, such as a raised and curved cab roof, trailer skirts and even TrailerTail aerodynamic systems (the pieces you see attached to the back of the trailer).