JBee

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Um, no. The stainless steel skins were never intended to carry the entire load, it's always been a sandwich type of construction where the skin stiffens the underlying structure. Anyone who understands manufactured structures understood that from the beginning. That's how an airplane, which is the analogy used by Elon, carries the load applied to the airframe. The skin is only part of the structure.

The wheels and suspension were never going to be attached to 3mm stainless steel sheet metal as the only structure. The skin of a commercial airliner is just thin aluminum, yet it adds incredible strength to the rest of the exoskeleton. But the previous year has informed me that you are not willing to be informed.
Arrrgh! Trigger words used! Must resist!! 😨😤🤬🥶😱🤯

Well I'm glad we've finally managed to get you to eat your humble exoskeleton sandwich at least.

Previously, not so long ago, your position was that the CT was purely gutless and was all just held together by the skin of it's teeth. Lol.
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WHIZZARD OF OZ

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...which is why they wouldn't skimp.

-Crissa
Imagine an Apocalyptic junk yard, and picture a broken CT or two, where people with a few basic battery powered tools can build their own 'MAD MAX' CYBER-B-B-Q ( Solar Shade//Batteries Included )
So maybe they'll slip an extra 'skimp' on the Barbie!
 

Bill837

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Thanks. It does look like 3mm.
So looking back, I see you said some have estimated the weight of the stainless to be 700-800lbs. Even at 3mm, that seem excessive to me. Those rear fenders as the largest panels on the truck and I would be surprised if they weigh over 100lbs a piece. Do you have a source for those estimates? I would like to see the assumptions they used.
 

wtibbit

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Here’s an exercise for today’s class, kids.

Estimate the surface area of each stainless steel exterior panel in centimeters. Multiply the sum the areas by 0.3 centimeter to find the total volume in cm, given 3 mm panel thickness. If the panel material weighs 8.0 grams per cubic centimeter, what is the total weight of all the panels?

Extra credit for showing your work.
 
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Bill837

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Here’s an exercise for today’s class, kids.

Estimate the surface area of each stainless steel exterior panel in centimeters. Multiply the sum the areas by 0.3 centimeter to find the total volume in cm, given 3 mm panel thickness. If the panel material weighs 7.85 grams per cubic centimeter, what is the total weight of all the panels?

Extra credit for showing your work.
To help the class, I found the following information. In the Metric. Rounded up American below that.

https://melindasteel.com/steel-sheets/89-cold-rolled-steel-sheet-3.html


1000mmx2000mm3mm48kg
40inx80in 1/8th 105lbs.

So I might be off 5-10lbs on the low side, but not by much on the rear fenders I dont think.
 

wtibbit

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To help the class, I found the following information. In the Metric. Rounded up American below that.

https://melindasteel.com/steel-sheets/89-cold-rolled-steel-sheet-3.html


1000mmx2000mm3mm48kg
40inx80in 1/8th 105lbs.

So I might be off 5-10lbs on the low side, but not by much on the rear fenders I dont think.
Now, class..... no cheating!

And, as a hint, don't overlook any panels - some may be small or hidden at times.

And for tomorrow's exercise, complete the same problem, but assume .09 cm thickness and 7.87 grams per cubic centimeter.

Extra points for answering this question: If the absolute difference in the answers to today's and tomorrow's question is X pounds, do the functional benefits of a 3 mm stainless steel exterior over a typical 20 gauge carbon steel exterior outweigh those extra pounds?
 

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But the thinner it is, the more shape it needs to hold its lines, the more support the edges need.

-Crissa
I agree, but being no longer depending on an exoskeleton for structural strength, they could easily have reduced the thickness from 11 to, say, 12 gauge to save weight. The edge of a panel could also have been folded back on itself. I'll be fascinating to see what they've done when all engineering, manufacturing, and economic factors were considered.
 

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So looking back, I see you said some have estimated the weight of the stainless to be 700-800lbs. Even at 3mm, that seem excessive to me. Those rear fenders as the largest panels on the truck and I would be surprised if they weigh over 100lbs a piece. Do you have a source for those estimates? I would like to see the assumptions they used.
Estimate the surface area and multiply by 5 lbs per sf of 3mm SS. My estimate came to 148 sf and 740 lbs. Warren Redlich estimated 700 lbs.

When the frunk lid is raised you can see the bracing structure that was needed to strengthen the lid. That lid is not likely to be 3mm thick to meet safety standards. I suspect that similar measures were taken on other parts of the exterior sheet metal. The quarter panels are clearly removable for replacement when damaged in an accident. I suspect they are made of thinner material. The doors would be the most likely to still be made of 3mm SS. Remember that Hans tried to dent one of the doors with sledge hammer, not other sections of the truck.
 

Crissa

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I agree, but being no longer depending on an exoskeleton for ...
There's no evidence of this being changed. None.

When the frunk lid is raised you can see the bracing structure that was needed to strengthen the lid. That lid is not likely to be 3mm thick to meet safety standards.
Maybe it is, or maybe it isn't, but it could be scored to create crumple zones. At impact level forces, the metal has no problem folding. It needs that under support to connect to other panels.

-Crissa
 


PilotPete

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Extra points for answering this question: If the absolute difference in the answers to today's and tomorrow's question is X pounds, do the functional benefits of a 3 mm stainless steel exterior over a typical 20 gauge carbon steel exterior outweigh those extra pounds?
The question can’t be answered. Not enough information. You appear to assume that the heavier panels don’t offset a weight reduction in the castings and actually weigh more..

Let’s just throw out random numbers for an example.

A Generic brand truck has a 700# ladder frame. The body panels weigh 300#. The internal panels 100#. Frame to support cab and doors-250# Frames to support body panels 250# Truck structure weight is 1600# (no, these are not accurate weights, or even proportional, just making a point)

The CT has 700# of 3mm skin. The castings are 200# each for front and rear. (Remember, they are AL-You-Min-EE-UM) Mounting stuff is 200#. Inner panels are 100#. You now have a 1400# structure.

So the answer to the question is, if utilizing the 3mm SS allows you to reduce the same or a larger amount of weight elsewhere in the vehicle, then YES the benefits “outweigh” everything by providing a strength and possible weight ADVANTAGE. And even if it is a little more (which I doubt) I think there is a strength advantage that exceeds the weight advantage.

I agree, but being no longer depending on an exoskeleton for structural strength,
You’re beginning an argument with an assumption for the foundation.

Look all, if you think that the entire truck was going to use 3mm SS with no substructure, then you have no idea about metal strength. Like I said in another thread, EM said this was moving the structure to the outside LIKE A PLANE (which has a structure beneath the skin that supports the MAJORITY of the load) He never said it was only the skin, and he used a PLANE as his example, and not a CRAB! (Or a lobster, or a shrimp, or even a jumbo shrimp, or a Bubba Gump shrimp, or a king crab, or any other crustacean) If it were the skin alone, I’m not sure 10mm would be thick enough.

As for the frunk lid, even the sacred 3mm SS in a single sheet with no bends or creases is going to twist over 70+ inches without reinforcement of some kind. When I see that, I think of it being extra stout. And if there is power close of any kind, you’re going to want to make sure there is no twist from wind or whatever during closing.

Here’s a project for the class. Can you look at the CT without any bias and assume what was announced is what is inside, until proven otherwise? Can you listen to EM’s words exactly as he said them, not as you wanted to hear them? There’s a difference between “not later than” and “around”, just as there is a difference between “like a plane” and “like a crab”.
 
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Mini2nut

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My prediction? Door skins and quarter panels will be thick. Frunk skin and front fenders will be a thinner gauge to allow for a crumple zone during a frontal collision.

Being a Tesla we know it’s going to achieve a 5-star crash test rating.
 

wtibbit

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You appear to assume that the heavier panels don’t offset a weight reduction in the castings and actually weigh more..) I think there is a strength advantage that exceeds the weight advantage.
Dang!!! I forgot that /s again…
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