Zerodefect

https://www.formula1-dictionary.net/chassis.html

WayneKerr

iTrader: (2)

but the second bullet already contradicts your claim of F1 chassis having flex built into it

"

• Maintain the suspension mounting locations so that handling is safe and consistent under high cornering and bump loads. This means that there is no flexing of the body, or at least to reduce flexing on lowest possible value."

gigaplex

iTrader: (2)

Did you read the whole thing? Further down:

Zerodefect

"Reduce flex to lowest value possible." Slow as a turd, would be below the lowest value wanted.

I'm not sure if F1 cars even have ball joints anymore. I think the arm just bends.

I forget what the exact chassis frequency in F1 is. I'm looking.

WayneKerr

iTrader: (2)

you're asking if i read the whole thing, meanwhile at the bottom it says exactly what the other guy was saying:

"Another reason torsional rigidity is mentioned here is that it greatly affects the suspension performance. The suspension itself is designed to allow the wheels/tires to follow the road's bumps and dips. If the chassis twists when a tire hits a bump, it acts like part of the suspension, meaning that tuning the suspension is difficult or impossible. Ideally, the chassis should be ultra-rigid, and the suspension compliant."

the thing people don't realize is this:
1:1 cars are designed (if you strip it down to its core) with the car with infinite stiffness in mind. ie the "theoretical" calcs are done with things that are rigid.

RC is done the other way. Everything is "free" Build the car stiff as hell and the car is almost undriveable.

i was in the stiff camp because that's all i dealt with in my professional life until I realize that's not how this hobby works. Can either keep hitting my head against the wall using a 5mm aluminum chassis or, use the "flex" as part of the tuning arsenal and just knock a lower lap time out. I know what I picked (despite going against every fiber of knowledge that I possess)

Zerodefect

Moto gp switched to carbon frames to get some flex. An f1 car is nearly entirely carbon. You can adjust the direction of the layup, for more flex.

https://www.motorsportmagazine.com/articles/motorcycles/motogp/why-motogp-has-gone-soft/

WayneKerr

iTrader: (2)

I don't have first hand knowledge on a f1 tub; but i know the oreca p2 car well enough, as well as another branded "new gen" tub well.

they have sphericals in the joints.

the point is, no one builds / manufactures the thing with "flex" in mind, because none of your geo and force calculations take that stuff into account (as it's almost impossible to) So all your antis are done with the assumption that the thing is a solid body (which is why sometimes when you put the car on a K&C rig, you're in for a surprise )

WayneKerr

iTrader: (2)

if you had two choices to go, using the same amount of material thus with the resulting weight being the same, no one would pick the option of lower torsional rigidity. every designer worth his salt would pick the config that gets him the stiffer tub, every time.

because otherwise when they get to the track and the car isn't responding to changes as well as it "should", someone will say "what the flying fuck" and when it gets back to the wet noodle being the cause, well heads are going to roll.

Zerodefect

I added a link above.

Scott_T

iTrader: (5)

Modified TCs on a big track are getting close. Plenty of sparks at night, and our track is very smooth. Although not the topic of this conversation, Mod Pro10s absolutely bottom out due to aero, hence we do run rubber stoppers on the centre shock.

Nerobro

iTrader: (2)

Those aren't F1 cars. Yes, most modern touring cars have some sort of "joint". F1 cars, especially at the bulkhead end, tend to use live hinges, which sections of arm designed to be hinges. They have some spring rate to them too.

With any even moderate FEA application you can model all of those things, and know exactly how they will behave. I can't speak for r/c manufacturers, but every car manufacturer is doing FEA, and know exactly where each mass is, and how it's going to interact with the shell, suspension, and tires.

maybe.



This is just plain wrong.





It's very effective, just due to tangent angle it's sprung completely the wrong way. While I get the analogy you're trying to make, it does not stand in this case. I could write several pages on both motorcycle swingarm, fork, and chassis flex.

You're trying to tell a story simply, that is not that simple. And isn't even settled now. You're putting lead on the chassis, when really, it was the suspension that dictated the chassis stiffness. As they got better dampers, and better dampers let them use the suspension instead of chassis flex. Also, bikes have to handle suspension loads in a near 120 deg arc, which cars do not. Bike suspension tuning, and car suspension tuning have very little to do with each other.

​​​​​​They have designed with the flex that the chassis will have in mind. Reducing flex nets you, in general, less traction, but the chassis is more easily controlled. It's a lot of typing to go into why this is.

A 1/12 scale car with no suspension has been done. A lot. Exactly as you describe. My Bolink 91 sport was like that. The early aluminum tamiya cars were like that. The whole t-plate car thing was more or less what you're describing. ​Gokarts are exactly that.

gwhiz

iTrader: (1)

I agree with you. However despite your example, the gist of the article is that the implicit goal of full scale race car chassis design is to increase torsional rigidity as much as possible.
"Rigidity is important to maintain precise control over the suspension geometry, that is, to keep the wheels firmly in contact with the race course surface. Unfortunately these two goals are often in direct conflict. Finding the best compromise between weight and rigidity is part of the art and science of race car engineering."
"Since the mid 60s, many high-end sports cars also adopted tubular space frame to enhance the rigidity / weight ratio."
"Another reason torsional rigidity is mentioned here is that it greatly affects the suspension performance. The suspension itself is designed to allow the wheels/tires to follow the road's bumps and dips. If the chassis twists when a tire hits a bump, it acts like part of the suspension, meaning that tuning the suspension is difficult or impossible. Ideally, the chassis should be ultra-rigid, and the suspension compliant."

In the pursuit of increasing torsional rigidity of full scale racing cars, great effort and money has been expended over many years.

There is something slightly mystifying going on with our 1:12 and 1:10 scale racing chassis. Something that favors deliberate, focused flex characteristics. I do not quite know what it is, but like many others I have noticed the benefit of manipulating flex. So we dont really want to follow what an F1 team, for example, is doing. Not until we figure out why our suspension is not working quite right.

My $0.02
Cheers

EDIT: I was late to the party as usual. I'll leave it anyways.

gigaplex

iTrader: (2)

Well if you're looking for proof that F1 does have flex and teams do exploit it, look at Technical Directive 39. Intentionally flexible floors were being used, the FIA implemented that rule to kerb it. Then after a different regulation change related to ride height, FIA removed TD39.

And then there's TD18 regarding flexible wings. Not strictly relevant here since it's aero and not suspension flexing, but it's still flex.

gigaplex

iTrader: (2)

I run modified TC at night. The only time I get sparks is at hard acceleration or deceleration. That's weight transfer, not aero, causing it.

gwhiz

iTrader: (1)

There might be some others here who remain unconvinced, but I am not among them.
I was only thinking about torsional rigidity and how those design paradigms may not be applicable to our puny little machines.