One of the main questions engineers and competitors have about the Tesla Cybertruck is how it would perform in a crash. Wouldn't its sharp lines hurt pedestrians even more in an accident? Is the Tesla Armor windshield safer or more dangerous than a regular one? Does the pickup truck have a crumple zone? How would a stainless-steel stressed-skin vehicle behave in a crash? Neither the company nor Elon Musk has answered these questions so far.
UPDATE: James Hatfield warned us the 30x is not a reference to stainless steel hardness but rather to the 300 series stainless steel. The article has been corrected.
We try our best to determine some answers to these questions by examining a stainless-steel car, the DeLorean DMC-12, and to a monoplane, a Fokker F-28. In crash tests.
Gallery: Tesla Cybertruck Pickup Truck Debut
The truth is that there is no production car with a stressed-skin structure. This article at the website UKEssays.com is about a race car, and it states the following on this solution:
“The next logical step for chassis development was the stressed-skin design. This is more difficult to construct than a spaceframe with the accurate folding, forming, drilling and riveting of sheet steel or modern composite materials. The lessons learnt in the aircraft industry do not usually apply directly in automotive practice. The loads on aircraft are widely distributed – the lift that holds a plane up, for example, is spread over the entire area of its wings. On a race/sports car, the loads are much more concentrated, being focused on the suspension mounting points.
Even when a method is developed to accept forces and spread them over a load-bearing skin, it becomes extremely inconvenient to make any modifications and may even require a major redesign. Analysis of the stresses in stressed skin construction is more difficult.
The continuous surface considerably complicates access for repair or replacement of the car’s mechanical components. This may also explain why stressed-skin construction was virtually unheard of in race cars before the modern mid-engine configuration. The majority of mid-engine race cars end their stressed-skin construction at the back of the cockpit, with either a space frame or the engine itself forming the remainder of the structure. For all these drawbacks, stressed-skin construction can potentially outperform any other form of race car construction in terms of torsional stiffness.”
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In other words, no one has done a production car with a stressed-skin structure before because it is so challenging. Car companies have also already invested so much in tooling and engineering for monocoques that it would be insane just to leave that behind. A company as young as Tesla does not have that sort of commitment.
But how would such a car behave in a crash test? The closest we got to understand what this design is capable of was with this NASA crash-test for a Fokker F-28. Monoplanes use stressed-skin design, as you are already aware.
The video description does not bring relevant information, such as how much the airplane structure was lifted before free-falling, but we found part of that on NASA’s blog. The Fokker F-28 was taken “more than 150 ft” (45.7 m) up in the air.
It seems to float a bit, but not enough to make the fall any less severe. With gravitational acceleration, the final speed would be around 108 km/h or 67 mph, well above the one used for most car crash-tests. The airplane structure does not present much damage, and, according to NASA researchers, it would have been a “survivable” accident.
The problem is that it is tough – if not impossible – to translate that into car terms, especially for one made of stainless steel. More than that, of an alloy that is stronger than regular stainless steel. The 30X is not a reference to hardness but rather to the 300 series stainless steel, as you can see in the tweet below.
Would it help to see the DeLorean DMC-12 crash in the main video? Or the one below? We don’t think so, but it is worth analyzing why.
The main reason is that the DeLorean only had stainless-steel panels, not a structure made of this material. These panels covered a fiberglass underbody built over a steel double-Y frame chassis. And all that was not very safe, as the video evaluations demonstrate. In the first one, the DeLorean even looks like the Cybertruck after the A-pillar moves up.
The stainless-steel panels bend, but they are of the SS304 kind, very different from the ones the Cybertruck will use. That keeps us wondering how the ultra-hard steel would behave on the Cybertruck. If a specific material is so hard it cannot bend, there is the danger it may break, sending shrapnel all over.
We honestly doubt this would be the case for the Cybertruck. After all, Tesla has already proved it can make incredibly safe cars. If you were to crash, despite the investment, you would better do so in a Tesla. Our doubt is more on the “how” than on the “if.”
Will the Cybertruck have a safety cell with stronger steel just around the passengers and regular stainless-steel for crumple zones? Will Tesla do the entire car with the same alloy but with different thicknesses? If you do not get crumpled yourself in a crash, how difficult will it be to repair a stressed-skin Cybertruck? Is its body even fixable?
These videos do not help us solve these doubts, but they show what a challenging vehicle this is. It has a bit of DeLorean, a bit of monoplane, and none of them can tell how safe it will be. Soon people will start to doubt it will even reach production the way it was proposed.
Only Tesla will be able to get all that straight. With two years for the production version deliveries still ahead of us, we guess the company is not in a rush to do so. Especially with 200,000 people in line to buy one regardless of the answers.