Cybertruck Front Casting Analysis (and Frunk Implications) - 3 vs 2 Chickens

[cvalue13]

Could there be some shallow storage at the front past the wheels ?

I agree there’s some nook and cranny in there - though I’d also think that given the geometry of it all it’s maybe better spot for putting some kit, like form-matching windshield wiper or coolant fluid reservoirs - for ease of reaching/pouring

@JBee had also pointed these out some bit ago

however,

as far as the usability of that space, worth baring in mind that in 3D the hood facets and wheel well encroachment, not to mention whatever structural elements are holding up that quarter-panel ‘nose’ (like the SS panel hanger) bifurcate the hood above the main rails, so don’t allow the space to go contiguously all the way to the hood edge:

That green bracket above is attached to and centered on the main rail, reaching forward towards the nose of the truck for attaching who knows what between the main rail outward to the quarter panel

sort of like so (in red below), just below the hood:

if from those brackets there are later added some structural reaches over to the front most portion the truck’s quarter panels (what else is giving those panels attachment/structure forward of the casting?), then now those two areas of the hood have other structural members in there, like so maybe:

No clue really, but all I know is:

• those brackets are substantive in size, and attached to the casting above the main beam

• so ‘up’ near the hood, those brackets bifurcate the possible hood volume above each main beam

• the nearby forwardmost portion of the quarter panels have nothing else apparent for them to attach to and provide structure (because we know it’s not the hood itself

• and so I assume something more is added between the bracket and the quarterpanels to hold up the quarterpanels etc., and the bracket we can see sure seems to be capable of given some struts over to the quarterpanels

so, those forward nose corners may have some useable volume in them, but if so I’m guessing it’s nooks and cranny’s better suited for some built-for purpose kit like wiper fluid reservoirs, etc.

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[cvalue13]

If he’s right on width, no. If he’s close, no.
this appears to be similar to the hummer wide but 3/4 as deep

the hummer is so big and I’ve paid so little attention, I can’t grasp the dimensions

but for reasons just discussed above RE those brackets above the CT’s main rails, I do from a design and aesthetics perspective see the Frunk taking a similar approach to the hummer’s inner mounldings and trim:l to the left/right of the Frunk

Obviously sans the headlights, but nonetheless the trim used to “smooth” out the look of the areas to L/R of Frunk, with access panels to eg reach fluid reservoirs, etc.

This is also how the lightning approaches the “dead” spaces created by structure around the Frunk

 

[charliemagpie]

Excellent.

Hopefully they will place windshield wiper / coolant fluid reservoirs etc. further back as possible in order to maximize the usable space at the front. A nook is handy too.

I do expect they will.

 

[anionic1]

SEE ALSO: this follow-on post with more Frunk comparisons to the Lightning

Now I understand why they got rid of lidar. They are implementing the tried and true homing chicken navigation system.

 

[anionic1]

hey .... how many guinea fowl is that equivalent to ?

Let’s not get apples and oranges here. What I got from this is that the CT will be able to produce eggs.

 

[cvalue13]

Excellent.

Hopefully they will place windshield wiper / coolant fluid reservoirs etc. further back as possible in order to maximize the usable space at the front. A nook is handy too.

I do expect they will.

It may not be helpful since so hastily put together, but this attempts to give some sense of where the attachment brackets sit (in green), then in my mind the sorts of cross-reaching supports for the quarterpanels (in yellow), and the man finally (in red) the strange geometry of the space created by a combo of the hood facets, the encroaching forward angle of the wheel well, etc

 

[charliemagpie]

Now I understand why they got rid of lidar. They are implementing the tried and true homing chicken navigation system.

Ford uses FSD homing Pigeons ?

 

[JRu]

The only question I have is; Can I fit my golf clubs in there? Need about 52" of length even if it's diagonal.

at least I'll be able to fit my disc golf discs

 

[MonkeyDeLuffy]

Say goodbye to the exoskeleton dream, twi-body casting basically. Like a model Y.

 

[anionic1]

Say goodbye to the exoskeleton dream, twi-body casting basically. Like a model Y.

Oh man, you are asking for trouble with a bold statement like that. Lets see how the responses go.

 

[cvalue13]

Say goodbye to the exoskeleton dream, twi-body casting basically. Like a model Y.

Oh man, you are asking for trouble with a bold statement like that. Lets see how the responses go.

I’m not an engineer, and am just gabbin’ here but:

On one hand, I think there’s a totally fair version of the observation that the new CT structural design is not the sort of “exoskeleton” that was described at unveil

On the other hand, if the CT has the towing and payload capacity described at unveil, there is zero chance the aluminum framing and casting of a Model Y would survive it - so something has to be performing that structural delta, and seems the SS is the only candidate

 

[anionic1]

I’m not an engineer, and am just gabbin’ here but:

On one hand, I think there’s a totally fair version of the observation that the new CT structural design is not the sort of “exoskeleton” that was described at unveil

On the other hand, if the CT has the towing and payload capacity described at unveil, there is zero chance the aluminum framing and casting of a Model Y would survive it - so something has to be performing that structural delta, and seems the SS is the only candidate

I don't actually think you can structurally attach a body panel like this, especially if its 3mm thick, and not factor it into the structural analysis. So it is very likely that they do play a significant roll.

 

[MonkeyDeLuffy]

I’m not an engineer, and am just gabbin’ here but:

On one hand, I think there’s a totally fair version of the observation that the new CT structural design is not the sort of “exoskeleton” that was described at unveil

On the other hand, if the CT has the towing and payload capacity described at unveil, there is zero chance the aluminum framing and casting of a Model Y would survive it - so something has to be performing that structural delta, and seems the SS is the only candidate

Exoskeleton was a key factor that convinced me CT would be made with high quality(due to its simplicity) and low cost at the unveil day of CT. Before this recent official photo from Tesla, I was reluctant to believe that CT could be following MY's path. On another note, I feel like this side view with front and back casting exposed was handed to public on purpose, carefully selected at least.

 

[cvalue13]

I don't actually think you can structurally attach a body panel like this, especially if its 3mm thick, and not factor it into the structural analysis. So it is very likely that they do play a significant roll.

No doubt.

What’s interesting to this layman’s eyes, though, is that the panel seams are such that there appears to be minimal overlap across any two - much less three - sections of the subframe.

That said, there still is overlap. So the panels act essentially as reinforcement braces connecting any two portions of the subframe. And they do so in a panel orientation best suited to add weight bearing strength, in the longitudinal direction of the truck.

Basically, the CT is built much like an aluminum framed ship with steel shell plating strakes.

 

[JBee]

I don't really want to rehash the exoskeleton discussions again, but seeing that we seem to be having an adult conversation here about structural design, I'd like to add my 2 cents.

Ultimately CT is a hybrid design where each part of it is leveraged for maximum capability.

In the strictest terms this is a hybridisation of cast, cabin, structural battery pack and SS skin and how it functions, and each needs to clearly identified for each individual part and SS panel. It also needs to have some conformity to useful load paths.

There are two main load path types in the vehicle, one being the crash impact load path that results in a damaged vehicle, the other what I call the "operational" load path, which is best understood as being from the tyre contact patch up to any loads supported by it.

Without opening rear sail panels for storage, only 1/3 of the SS skin is fixed and attached onto the CT in such a way that it can offer any support structure. This is because 2/3 of the SS skin are opening doors, frunk and tailgate. With opening sails this would increase to around 5/6 of the skin that is opening.

This means that the opening skin has to be hinged and latched for it to open, which in turn means there is no mechanical way to make a load path go through it for operational loads, and the skin only works as a crash load path by being compressed against the interior body frame on impact.

The skin on the opening acts as the structural member of the door allowing it to use less, or even no internal framing, and only the thickness and shape of the SS skin. In the cases of the opening, the skin is operating as a load bearing material for both crash and operational loads, as the function of a structurally independent opening door. As such it could be considered a "exoskeleton" by definition, but seeing that it is only attached by hinges and latches to the main CT body, it is not capable of supporting the internal casts and cabin in a operation load path.

That means it is only the front fender, and possibly the rear sail fender, if it doesn't open, that can actually be attached to the CT in a mechanical way that allows for loads to be passed through them. As such the amount that the SS skin can contribute to the structural rigidity of the frame is limited to those areas only, and given that the casts are attached to the drive assembly and suspension, and the suspension risers are supported by the cabin frame and casts, there is little to no load that will go through the outside skins themselves, without being forced to make a detour there intentionally.

There is another reason why loads through the rigid skin panels is not advisable, and that is that operational loads, from driving down a bumpy path at speed offroad, could cause the fairly flat 2D panels to buckle and twist, including the doors, which could stop them from opening etc.

Now if you consider the benefits of SS, you must take all of them as a whole, and not only just for structural purposes. For example the SS gives customers a a tough no fuss finish and costs Tesla nothing to paint, which improves the value and affordability to customers. 304 SS currently costs between $2-$3.50kg, so using $3.50 and the material mass breakdown I did in another post you get this:

Stainless Estimates	Mass kg/sqm	sqm	mass	lb	Cost
SS 3mm	24​		279.2​	616.4​	$977.26​
SS 2mm	16​	11.634​	186.1​	410.9​	$651.50​
Frunk (w Grill)		2​	48.0​	106.0​	$168.00​
Tailgate		1.26​	30.2​	66.8​	$105.84​
Total ends		3.26​	78.2​	172.7​	$273.84​
Front door		1.02​	24.5​	54.0​	$85.68​
Rear Door		1.103​	26.5​	58.4​	$92.65​
Front fender		0.37​	8.9​	19.6​	$31.08​
Rear Fender		1.532​	36.8​	81.2​	$128.69​
Cabin Frame		0.162​	3.9​	8.6​	$13.61​
Total 2x Sides		8.374​	201.0​	443.7​	$703.42​
Total Opening SS		7.506​	180.1​	397.7​	$630.50​
Total Fixed SS		4.128​	99.1​	218.7​	$346.75​

As is clear from the table, the cost of the SS skin, given how it is used structurally as door framing, and as a untreated non-painted surface, means that it will be in fact cheaper to produce the vehicle with SS than with aluminium and paint (like MS) and even mild steel, if you cost painting alone at around $1200 per vehicle (which is low given capex for painting).

With that understanding in hand, accepting the internal structure as the CT's primary structure becomes a lot more palatable.

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