The tunnel seems an Ideal spot to run the coolant hoses and power steering hoses.

 

I haven't tried sitting in my preordered C8 but I have a McLaren 720s and sitting in and out is a breeze. Buttocks in first and the reverse to get our. The big door wall allows you to sit up higher and slide in to the seat. If you try sitting in it feet first, it's a struggle.

 

So, what is amateurish and wrong about this 'Uni' chassis? Actually, there are 4 triangles that make up a pyramid where all forces act save for impact forces. Go for it.

 

The C8 is certainly roomier than the C7...

 

that tall wall you have to get over to get in sounds just like my 86.😆

 

I think you misunderstood what I was saying; I wasn't suggesting they put the HVAC controls on the dash, I suggested putting them flat on top on the center tunnel, instead of raised and sloped. That way you don't have the awkward barrier between driver and passenger and cramped looking/feeling cabin.

 

Speaking of triangles, when the Cobra roadster was converted into a coupe the rules allowed such structure as necessary to support the new bodywork. The roadster was the perfect example of a flexible flyer chassis. So the chassis was stiffened by building this structure over the gear box. Bolted so the gear box could be removed. The resulting stiffened chassis immediately started to work the tires and Shelby was on the phone ordering wider tires from Goodyear. There are additional photos other parts of the "body supporting structure" which just "happened" to stiffen the chassis. The FIA or Ferrari never challenged this.
One of the drivers said that the coupe handled so much better that he would have rather raced it anywhere including the Ring.
And then there's Zora and the new chassis for the Grand Sport, but that's another story

 

Can you comment on this essay?

 

Shaka,

Who is "you"? Kodiak Bear or Supermassive?

Thanks

Kodiak Bear

 

You. Do you approve of the design?

 

I do, but more important for this thread is help explain the potential for dual purpose use of the C8 "backbone" as chassis structure and battery box. I don't know how much more mass that potential dual use added to the C8 structure, if any. Maybe the backbone as required for the chassis was already strong enough to serve as a "battery box"? Whatever it has to be less than the duplicate structure as the article says. This assumes that a hybrid model C8 will be built.

As a design, the Uni-chassis should be interesting for a mfg like Superformance where the same chassis could reside in the Cobra roadster, the Daytona coupe and the Corvette Grand Sport that they sell. And in the GR-1 that they will be selling?

I have a copy of the Uni-chassis patent, but as I am no longer a member of the SAE, I don't know if there are papers further explaining the Uni-chassis. I do have Chris's book. However I know of no one using a Uni-chassis as he patented.

Here's GM's latest EV announcement (NOT HYBRID)
https://media.gm.com/media/us/en/gm/...r/0304-ev.html

an excerpt says::Upcoming Launches and Reveals

Chevrolet, Cadillac, GMC and Buick will all be launching new EVs starting this year. The next new Chevrolet EV will be a new version of the Bolt EV, launching in late 2020, followed by the 2022 Bolt EUV, launching Summer 2021. The Bolt EUV will be the first vehicle outside of the Cadillac brand to feature Super Cruise, the industry's first true hands-free driving technology for the highway, which GM will expand to 22 vehicles by 2023, including 10 by next year.

The Cruise Origin, a self-driving, electric shared vehicle, shown to the public in January 2020 in San Francisco, was the first product revealed using GM’s third generation EV platform and Ultium batteries. Next will be the Cadillac Lyriq luxury SUV in April. Details about its launch will be shared then. The reveal of the Ultium-powered GMC HUMMER EV will follow on May 20. Production is expected to begin in Fall 2021 at GM’s Detroit-Hamtramck assembly plant, GM’s first assembly plant 100 percent dedicated to EV production.

 

McLaren is smaller inside with less leg room and not roomier....

 

First off I was poking a little fun at you since you have a tendency to poo-poo the engineering of the Corvette chassis regardless of generation. The triangles and circles joke was about the MS paint additions to pictures showing something that you are trying to portray, but most of us non-engineer types just see it and go...huh?

The uni-chassis seems similar to the chassis design of the C8 with its center tunnel taking most of the structural load of the entire car so I have nothing to say about it. I feel like your expectations for chassis design are not aligned with the reality of a passenger car because most of your assertions are based upon race car chassis design which allows for a much higher structural rigidity because the ride can be compromised for all out handling. I've driven a few tube chassis race car like frames on the street and while they are fun cars to drive, they would be a nightmare to live with, kinda like trying to daily an Ariel Atom.

When having to deal with harmonics and vibration, the chassis has to be designed in such a way to afford some flex...this is not a miss by engineering teams designing these cars. Any engineer could build a chassis structure that is rigid, its the job of designing a compliant AND capable chassis that requires skill and quite a bit of engineering and material science know how. Of course with the more powerful design software these things can be nearly eliminated before casting the first parts of a prototype chassis. The fact that the C8 has been reviewed and reviewers all say the same thing about how the car rides...being excellent in all modes...it would seem that they got it right. The Z06, GS, and ZR1 will get different suspension tunes, and we may be blessed with a Multimatic spool valve setup for a Z07 package (one could hope) and the ride will be dialed in for more aggressive feel and less touring car feel.

I like to envision that the flex in the chassis is part of the engineer's design for the suspension, as iff the flex is there to damp out some of the nuisances of street driving and daily driving a car.

 

I have never heard of designing flex into a chassis as a way of working with any issues about the quality of ride (NVH noise, vibration, and harshness) or road holding. New one on me.

 

Well, you obviously haven't raced go carts. The chassis is the suspension. You tune the flex. The C5,6 and 7 chassis flex like a bitch. Therein lies their beauty. The F488 intentionally added the 'Warp Factor" to it's frame. Why? Do you know that you can't perform corner weight adjustments to the above mentioned Vettes? Why do you suppose that is? They are a challenge to drive at the limit, but they get the numbers. What is their story?

 

Fascinating
"Well, you obviously haven't raced go carts. The chassis is the suspension. You tune the flex. The C5,6 and 7 chassis flex like a bitch. Therein lies their beauty. The F488 intentionally added the 'Warp Factor" to it's frame. Why? Do you know that you can't perform corner weight adjustments to the above mentioned Vettes? Why do you suppose that is? They are a challenge to drive at the limit, but they get the numbers. What is their story?"

First response
There is no such thing as an object totally without out flex although I wouldn't suggest testing that theory by slamming your fist into a 2000lb block of steel
Go carts are tuned that way because the rules do not allow "suspensions" so they are deliberately design the chassis to flex to make up for that lack. By the way, the midget racers also have rule against suspensions of some types and engine placement after a bunch of formula (junior?)cars showed up with engines in rear and four wheel independent suspension and cleaned up at the races.
Corner weights or wedging? That isn't a flex but a warp that is not expected to flex out?
The C series. If flex is such a beauty why does every generation brag about how much stiffer it is? There is a limit before flex sets so you have to deal with that when tuning the suspension system.

My thinking is still that flex is not a desired designed condition but a limiting condition that must be dealt with when tuning a car. Being able to take advantage of that is good engineering not a desired design goal? Witness the C4 flexible flyer, or the Cobra roadster.

​​​​​​​If this is boring to the the thread readers, lets take it off line please as I really want to get my head around this. Maybe it's just a matter of vocabulary. But it's going to bug me until I understand what's going on.

 

Good to know.

 

We are not supposed to let the information leak but for Forum members l will make an exception. This car is built in Kentucky. Long Guns could not be adequately accommodated in the C7. This is the built in Gun compartment.

 

The way it was described to me is that chassis flex used to be an issue due to material and manufacturing limitations. As computer assisted drawing became mainstream it was possible to more accurately determine where to gusset and brace for structural rigidity. Today I can hop on Solid Works and bang out simple chassis design and add virtual stresses to my design and I can change the material properties of my elements to determine the ideal combinations of materials to provide the ideal weight vs. rigidity. However I am not quite at the point where I can model a full suspension properly. The engineers that do this for a living however can. The worst thing about chassis design is calculating how the suspension interacts with it. Not designing a chassis properly can have issues with harmonic frequencies that can cause all sorts of issues within the chassis and suspension, one of the first lessons of harmonics any engineer hears about is the Tacoma Narrows Bridge, it was finally discovered to be something other than resonance (aeroelastic flutter-which is a wind induced harmonic issue, but I digress). The real problem is that it can make a car behave unpredictably.

So modern cars are built with a sort of damping system in the form of mild chassis flex to make passenger car much more stable at higher speeds. Race cars are built to an extreme and can run much much stiffer chassis and much stiffer suspension settings than you would find on a passenger car. These cars are typically unwieldy at public road speeds and are not really subjected to constant speeds, race cars around a track are either accelerating or decelerating...no one uses cruise control at a race track so any harmonic issues can be dealt with by gearing changes or simply avoiding speeds at which it is noticeable.

Now Shaka has the correct perspective that Corvette chassis' are compromised and could be better "sports cars" with modifications to the rigidity. Like he stated about the 488 having it intentionally built into the car and they even gave it a name, chassis flex for road going automobiles is a necessity. The constant improvements reported each new generation in chassis rigidity is all due to the advancement of material science. With more and more powerful computer modeling, engineers can dial more and more rigidity into the chassis and still maintain a ride with little to no resonance issues. Eventually, I believe that with 3D printed metal structures, this will no longer be an issue in sports cars, until that technology goes mainstream though, we will see incremental chassis rigidity increases as the power of the software increases.

 

"So modern cars are built with a sort of damping system in the form of mild chassis flex to make passenger car much more stable at higher speeds"
Isn't that interesting? All I've ever read says "they stiffened the chassis for better handling" or "they installed/designed the safety structure in such a way as to stiffen the chassis" or "the chassis was a flexible flyer" (C4)The idea being if the chassis was stiff you could control the response of the car through the suspension. By inference the chassis flex was not predictable.

"The constant improvements reported each new generation in chassis rigidity is all due to the advancement of material science."
I know what it's due to, I thought it was the desired goal as in:. engineers can ( and want to) dial more and more rigidity into the chassis and still maintain a ride with little to no resonance issues.

chassis flex for road going automobiles is a necessity
Until this dialog started I would have classified that as quackery

Please don't take this as an insult, but can you point me to any relatively inexpensive technical references so I can read a bit of background. No press releases or marketing hype if possible.

And thanks for taking the time to respond.