How Tesla’s Cybertruck Turns Car Engineering Norms Upside-Down
Its stainless steel skin practically screams the question ”What if SpaceX built a pickup truck?!”
Now that your retinas have cooled a little after sizzling at the sight of the Cybertruck, how about we bore a little deeper into it what’s beneath its doorstop surface?
I don’t mean, of course, literally boring into it. That’d end as a bright-red drill bit, madly smoking in a very shallow hole. And be no more than an amusing irritant to the several square yards of unpainted, 3mm-thick, won’t-rust, easy-buff, tough-stuff, stainless steel cloaking the truck. Think of it as Doc Brown’s DeLorean with a rhino-thick skin—fortunately sans the mismatched painted bumpers of John Z’s dream car. Instead, designer Franz von Holzhausen has fitted Elon’s fever-dream truck with simple, raw, black, unpainted plastic ones. (And yes, a thesis could be written about unconventional auto tycoons’ strange attraction to stainless steel and upward-rising doors.)
The plusses for a folded stainless steel, origami truck are compelling: no paint shop and no expensive tooling. No Godzilla-scale stamping machines stomping it with multiple strikes. Without all that, the capital and environmental costs of using stainless steel body panels are small. And big attractions for a company that’s sensitive to both types of green—cash and environmentalism. Just groove the steel where it’s supposed to fold (avoiding cracks) and bend it on simple, cheap machines (like I was actually doing last week with my garage vise!)
Brilliant … but prickly with trade-offs. Unlike the strength-to-weight efficiency of compound curves (feathery eggshells are the epitome), the flat-ish planes between the Cybertruck’s simple bends require greater thickness to resist buckling compression loads or wrinkling oil-canning. Adding weight.
To counter this? Ditch the heavy, traditional, body-on-frame, and rethink the structure as weight-efficient trussed bridge in its simplest load-spreading configuration: a triangle set on its hypotenuse. One side is the Cybertruck’s wedgy cab, the other, its tapered, sail-sided bed, their meeting point at the truck’s tall peak resulting in a huge cross-sectional area for maximum stiffness.
This steel-clad, skeletal structure has ancestors dating to the 1934 Chrysler Airflow, and in modern times, some similarity to Saturn’s old skeletal steel chassis that was skinned with shopping-cart-resistant plastic skins. A one-minute walk from von Holzhausen’s Design Center is the sprawling SpaceX facility where teams of engineers have deep-dived to become overnight experts on stainless steel after chucking carbon-composites for their mammoth Buck Rogers Starship. If anything needs to be simultaneously light but robust, it’s the rocket you’re relying on to get you to Mars (and back). Structurally, the Cybertruck is … absolutely gorgeous. But the aerodynamics of that peaky profile?
It almost looks like a deliberate, suicidal attempt to trigger boundary separation—a potential drag-raising catastrophe for limited-energy EVs. And an odd 180 turn from the Model X and Y, which have such delicately arched profiles precisely to avoid drag-raising trip wires like this.
Tesla might have erased the problem with active suction to bend the boundary-layer downward just aft of that peak. Gordon Murray’s McLaren F1 used this trick, and SpaceX has plenty of expertise in active measures to manipulate airflow around its re-entering Falcon 9 first stages. However, with the bed cover deployed, the angle of its vast descending surface is evidently shallow enough for the flow to naturally reattach. The benefit being that it harvests a useful fraction of the air pressure that blocky, open-bed trucks almost entirely forfeit. Actually, the tougher aerodynamic trick has been coaxing the temperamental flow around those sharp A-pillars.
Balancing weight against manufacturing cost against aerodynamics is a mind-bending, three-dimensional puzzle. Does the origami’s manufacturing and capital savings outweigh the additional material and air drag? If this calculation pencils out, will all of Tesla’s next-generation cars go origami? Or maybe a there’s narrower sweet spot for lower-speed, urban EVs, where aero’s less impactful?
Motivating this cubist Picasso into kinetic sculpture is Tesla’s latest drivetrain; the Model S/X’s large inductive rear motor remains in back, with the Model 3’s permanent-magnet rear motor repurposed up front. Officially, the pairing’s called Raven, and an odd characteristic of it is that, at very light loads, the Cybertruck could be front-wheel driven.
Rivian, of course, has leaped straight to the ultimate in individual wheel-slip control: four motors, one per wheel. But Tesla’s upcoming 1,000-plus-hp Plaid powertrain (two rear motors, one up front) has already lapped the Nürburgring in a Model S (and now has me wondering if its rear motors are packaged super-close together in anticipation of the Cybertruck’s long suspension links). Might we see a Cybertruck Nürburgring lap time? It would be a spectacular sight to see its bed canopy erect on the straights for low drag and roll down in the corners to lower the center of gravity. That’d be a record Porsche wouldn’t be challenging.
If you’re accustomed to looking beneath EVs at their batteries, they characteristically span as much of the wheelbase and track width as possible. However, the large cylindrical cavity needed for the bed cover shortens the battery’s footprint by over a foot. Bad news for kW-hr capacity? Not really. Long Range Cybertrucks will have double-stacked battery boxes (like the apocryphal Faraday Future FF91). And it turns out that EV trucks would prefer to have their battery weight shifted forward anyway, to preserve payload capacity.
If the Cybertruck is a shock to the eyes, it’s a jump-start to reimagining the foundational assumptions about vehicle appearance, engineering, and manufacturing. Remember Elon Musk’s plans to leapfrog car assembly with a high-speed, robotic, alien dreadnaught ”machine-that-builds-the-machine” that would fire-hose Model 3s out its tailpipe? He had to sheepishly remove some of the robots and conveyor belts to speed things up. Now, the ”machines-that-will-build” the Cybertruck will go dramatically skinnier, scaling the dreadnaught down to simple dinghies that groove and bend (with the $200 million paint shop getting an auditor’s line drawn through it). Real progress is assembled from the debris of failures.
Speaking of which, I’m trying to figure out the folds to make an origami paper-model Cybertruck. Hmmm. Fold here, now here … Errr, start again.