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So Sato has a recent quote about chassis flex in the SA car. What exactly is the relevance of a chassis with lots of flex? What specific difficulties does it present on the track?

Since most suspension changes are related to rates, be it as springs, anti-roll bar and whatnot, looking at them simply its how "springy" the components are when loads are applied to it. This applies to how the motion of the wheels are controlled and so forth. Now if the chassis is not stiff, any controllable changes you can affect by changing your anti-roll, spring, tire pressure and so forth, will be on top of a uncontrollable spring of the chassis itself. And this can result in setup doing not something that you want to do, and thus you'll be chasing the setup around and not necessarily know whether something actually did what you tried to do, or just simply miss the whole point.

Chassis flex can affect the way suspension works. A chassis that isn't very stiff can render suspension settings ineffective. For example, you can encounter more roll than you wanted, or the wheels may come off the ground because the suspension is calibrated for a different "type" of chassis.

Ask any engineer, and they would love a chassis with zero flex. It's the holy grail of chassis engineers. Of course, you could built one, but it would probably weigh ten metric tonnes.
Imagine a shoe box. Take the top off, and grasp the box by each end. It flexes quite easily. Now, put the cover back on, and repeat the flexing. This time, with a closed box, it is much more rigid and flexes a lot less. That is what a convertible or open cockpit looks like when you apply the same type of flexing motion. It's a problem, and in open cockpits they just make it stiffer in that area. In a road going convertible, they add internal stiuffening structures to return it closer to the chassis stiffness it's closed top sibling enjoys.

To what extent is chassis flex due to aeroelasticity, do you think?

Aeroelasticity and bending due to structural forces is not exactly the same thing.

SCARY
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SIX SECONDS OF THE PACE
Why even bother

So Sato has a recent quote about chassis flex in the SA car. What exactly is the relevance of a chassis with lots of flex?

If Sato is actually feeling the chassis flex then that is a horrible sign. All F1 cars flex, but you should not be able to actually feel it. If Sato is feeling it, then it's probably flexing by centimeters. Typically, you'd want the flex to be limited to the micrometer range. Roughly, the car is off by an order of ten thousand. Ouch!

Truly, why bother racing this thing? It's dangerous just to have him out on the track.

ginsu wrote:

So Sato has a recent quote about chassis flex in the SA car. What exactly is the relevance of a chassis with lots of flex?

If Sato is actually feeling the chassis flex then that is a horrible sign. All F1 cars flex, but you should not be able to actually feel it. If Sato is feeling it, then it's probably flexing by centimeters. Typically, you'd want the flex to be limited to the micrometer range. Roughly, the car is off by an order of ten thousand. Ouch!

Truly, why bother racing this thing? It's dangerous just to have him out on the track.

Trully well said.

ginsu wrote: If Sato is actually feeling the chassis flex then that is a horrible sign. All F1 cars flex, but you should not be able to actually feel it. If Sato is feeling it, then it's probably flexing by centimeters.

I find this hard to agree with. Just because Sato is not as quick as some of his comtemporaries, doesn't mean that he isn't a highly skilled racing driver. Who are you to say he isn't one of the best drivers in the world? This is especially the case when he is compared against someone like Jenson Button who has been racing karts since the age of three or something stupid. I don't think Sato even sat in a racing car until he was eighteen. Just because he is a little slower than some of his team mates doesn't mean that he doesn't have highly tuned feel for a part of the car that some other drivers might not have.

On another note, can anyone that works with carbon fibre clasify if it is even possible for a chassis to flex as much as centimetres because I wouldn't have thought this would be possible. I know these days it is not uncommon to hear of chassis with 23,000 lb/ft per degree of flex, probably more.

"Everything flexes on a car... everything. The important thing is how much" -Ross Brawn-

Like Ross Brawn says: "Everything flexes the secret of F1 is knowing exactly how much each part flexes and preventing it"

I read it somewhere!

maybe the twin keel is flexing....

Sato started racing late, and yet he has earned his place in F1 to begin with, he was not British F3 Champion for nothing. Sure he crashes a lot, which is definitely a problem, but the same can be said for a lot of other driver early on in his career.

RacingManiac wrote:maybe the twin keel is flexing....

Maybe it is just a 4 year old chassis and standards have changed.

Actually, something as simple as the vertical stiffness of the car can affect things like the damper effectiveness. That is something that a driver can feel. It's not necessarily that he feels his body heaving up and down because even the Renaults and McLarens vibrate all over the place (just watch the onboard cams) and they definitely do not have floppy cars.

Monstrobolaxa wrote:Like Ross Brawn says: "Everything flexes the secret of F1 is knowing exactly how much each part flexes and preventing it"

I read it somewhere!

Steve Matchett has quoted this also, so I'm going to assume it was The Chariot Makers