Aero as a surface: Praga on the Bohema hypercar 

A visit to the Praga booth came at an opportune moment as Car Design News continued its focus on surfacing this month.

Even on a static stand the Bohema hypercar cuts quite a figure, an angry, angular arrowhead of carbonfibre slashes and creases. In purple, gold and black — a unique customer order — it would be easy to assume much of this is decorative. Elaborate work designed to foster an appearance that matches its hefty price tag. But that is entirely inaccurate. 

The Bohema comes from the pen of independent designer Juraj Mitro who has shown a fascination for high performance materials, in particular carbonfibre. Super light, super strong and beautiful either bare or finished as it is here in a bright colour, the material affords plenty of freedom to design compelling structures and surfaces. 

"Juraj has been working with carbonfibre for close to 30 years with his own hands, pretty much on daily basis," says chief marketing officer Ivan Krakora from the stand. "He understands the material through and through, and while he's a car designer, he's also an engineer. Every single aerodynamic component was co-developed with him, and he would always do any aerodynamic adjustments in a way that fits the overall design of the car."

Indeed, aerodynamics was central to the design of the Bohema and we can see that immediately. The low nose and waveform diffuser that sits below it like the wing of a hydrofoil; the twin-layer boot spoiler; the central air intake that adorns the roof, and the numerous gullies and gussets that cut into the side panels. Viewed from a distance, it appears somewhat smooth and flowing. Up close it is a complex network of individual surfaces that harmonise around the comparatively tall cabin.

Aerodynamics, affirms Krakora, sat "very, very high" in the list of priorities. It all makes sense when you learn that the aim was to take on behemoths like the Aston Martin Valkyrie, and the broader goal of creating the fastest road car built for the track. But such is the intricacy of the surfacing and the architectural nature of the overall structure, the Bohema seems to reflect a slightly different product — a track car that is able to go on the road should it need to. (It turns out the car is very capable as a grand tourer, with owners often doing cross-continental road trips.)

The Bohema is in fact an evolution of the R1, a track-only car that launched around 2013. The R1 later became the R1R as a roadworthy version, but it didn't quite tick the right boxes for owners who wanted more than one seat and a few basic creature comforts like air conditioning. It is remarkable then that the Bohema in its current form manages to cram two seats into that central bullet-shaped fuselage, but that it does. A slight asymmetry means driver and passenger do not rub elbows. 

"I'd like to say that dome is a design element, but it's more functional," says Krakora. "Aerodynamics dictates that you want the cockpit to be as narrow as possible. And that's exactly what it is. We spent three months in cardboard boxes just trying to figure out how you can fit two people to the most narrow space possible, which we achieved." 

The team also took inspiration from the distinctive forms of Le Mans race cars, although the Bohema's surfacing is far more complex than almost anything we have seen on that front. 

It is not often that our eye is drawn to a car's wing mirrors — especially when there is so much else going on — but the antennae-like structures that loom out from behind the front fenders and connect directly to that central thorax. The challenges stemmed from regulations — they must be visible from a certain point — and ensuring they had a firm fixing point. 

"Because the car is all about being lightweight, the only structural part of the car is in the middle," explains Krakora, "and everything you see on the side are basically aerodynamic covers. We couldn't mount the mirror onto the wheel arch because it would vibrate, so we had no other choice than to mount it onto the monocoque." The result is a pair of distinctive, insect-like protrusions from either side of the cabin that feel less like components and more like additional body surfaces.

Naturally, Juraj and the team took the opportunity to tweak the aero in the process. "The arm actually helps to calm down the air and channel it towards the air intake, and the shape of the mirror provides a low pressure zone at the bottom, so it naturally sucks the air out from the interior. There are always multiple functions to the design."