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Comment by RobertRoberts | Hacker News Reader

I just had a discussion with a friend who is an engineer. He thought this truck design was done by a 3rd grader and is evidence of Elon going crazy (literally).

I love the design. It's how I wanted my own vehicle to be made. The most simple possible with the most strength and easiest to repair. I know it's ugly, but I...don't...care.

Please, someone tell me why stainless steel (as Elon designed this) is superior to aluminium (this is my friends primary argument, I think he hates steel) he said it was lighter and cheaper and didn't corrode as easily. (I know, but what can I say?)

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“Strength” is the last thing you want in a car. Cars crumple in an accident because that significantly cuts down on injuries to both the passengers and whatever is hit; if your car won’t crumple all that force transfers in to flinging you straight through the windshield.

Do you think the designers might have considered this prior to releasing the car?

I get it, people might make mistakes in the design etc, but it’s not as if this is the first time Tesla has produced and released a vehicle into production, do you think they’ve considered how this car will cope with an accident ? Maybe you feel they think stainless is “cool” so went for it?

I’m totally aware you might be right, but I doubt they haven’t thought of this.

Many analysts (and Elon himself) put Tesla at between 10-20 months from bankruptcy at any given moment. [0]

In all likelihood it didn't matter what the truck looked like at the reveal. All that mattered was that it justified another capital raise.

[0] https://bgr.com/2019/05/20/elon-musk-tesla-cut-costs-running...

Considering Tesla’s history, and the fact that this is pretty clearly a concept car, I genuinely don’t think that the designers have considered stuff as pedestrian as “crash safety”, no

I think the issue behind this design decision and the look is that this is meant to be SpaceX’s future Mars Rover as Musk revealed in a tweet. I’m thinking that Musk just wants to mass produce it to work out some of the “bugs” before they create the pressurized version for Mars

Aluminum is harder to work / weld / repair and is more expensive than steel. Yes, aluminum is much lighter and oxidizes less destructively.

You don't see a lot of manufacturers wasting weight on very robust body panels--in fact, quite the opposite, preferring aluminum or carbon fiber for panels, hood, and roof when practical.

I really intended to ask for a fair comparison not just ammo for an argument. So thanks for this, my original comment was written poorly.

My experience with aluminum is not great. But I appreciate understanding the value/cost/benefits for different design decisions.

Something in programming that helps a lot is to know when to follow the crowd and when to buck the system.

Stainless steel is cheaper by weight. Unlike aluminum, it doesn't need paint.

In the presentation they hit the door panel with a sledgehammer. No dint. I don’t think I need to explain what would have happened if it were aluminium.

Pray tell, what would happen? Saturn famously made their door skins out of plastic. Chevrolet uses fiberglass on the Corvette. Plenty of higher end vehicles use aluminum for the frame, and of course Ford uses aluminum for its light duty truck beds.

If the door panel were made of aluminium, it would dint when hit with a sledgehammer.

They dented a steel door as part of the demo. It'll all depend on thickness, alloy, and treatment.

Indeed. Do you have a point?

Indeed. Do you have a point?

That they could've made a dent resistant door out of aluminum.

Not sure exactly what series of aluminum car panels are made from, I highly doubt its 7000 series, probably a 2000 or 5000, maximum Yield strength for T6 temper is in 250-350MPa range. That’s still pretty soft.

Cold rolled full hard 301 stainless has yield strength of 1000 MPa. Tesla claims a 30x ultra hard, no one knows quite what that means yet, so maybe that’s 1500MPa yield strength. So call it 6-8x more dent resistant than aluminum at same thickness.

Tesla is using 3mm thick stainless. I can’t imagine standard car panels are more than 1.5mm thick.

Stiffness grows with square of cross sectional thickness.

So it is plausible Tesla’s panels are 20-30x stiffer than regular door panel.

Maybe that’s where they get their 30X from.

What’s your math say?

The "sledge hammer" was a deadblow hammer containing sand or metal beads to distribute impact over a longer period of time.

They used this dead-blow feature on the Cybertruck, but twisted the hammer 90 degrees on the "competitor truck" door. You can even see the effect; in the three hits on the white door, only the two where the hammer was twisted left significant dents. [1]

[1] https://twitter.com/paully_steaks/status/1197915960646107136

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