Do we need suspension?

[Ciro Pabón]

An infinitely rigid wheel that provides no suspension at all cannot impulse a car.

The only way for a car to move forward is if you develop a differential grip in the wheel. You can read here:

That infinitely rigid wheel would also give you no steering at all.

Of course, that would solve the problem of comfort and make engines unnecessary, as the car wouldn't move at all.

Triple play: you would have terrible handling and no acceleration at all, but at least you would look stupid.

Wait...

[bill shoe]

JT, great pics in this thread. You're essentially doing the "Caption Competition" thread in reverse. Caption Competition posts take an interesting picture and add interesting/funny words. You take the words and add the corresponding picture. Works great in either direction, nice.

[Robbobnob]

if they didnt need suspension they wouldnt have it, there was a great shot of the Torro Rosso with its suspension and steering arms all in action

[hardingfv32]

Ciro Pabón

What you say could be true, but I am not sure it has anything to do with the main premise.

I would say a lot of a tire's design features, camber angle, slip angle, etc. are a legacy of the need for the tire to be compliant to surface conditions. Would any of these tire features be relevant with say a solid rubber tire, a few molecules thick?

Brian

[HampusA]

Are you also implying that with a perfectly dead smooth track, stuff like a differential would not be needed aswell?

[hardingfv32]

What are you using the differential for?

Brian

[HampusA]

Getting power down to the ground in and out of corners. i.e "grip".

[hardingfv32]

Even with no suspension we have load transfer in the corners, so I would think the inside tire has less grip than the outside. Is this what you are thinking, torque distribution?

Brian

[DaveW]

... What is the nature or cause of the imbalance that you are proposing? Is it caused by the chassis or the aero package?

The goal is no suspension, not simplicity. We could have adjustable aero features

A vehicle that has lateral balance neither over-steers nor under-steers. Balance is affected by a number of vehicle properties, but the adjustable property in a real vehicle is roll moment distribution, which is usually controlled by front & rear roll stiffness - provided that the vehicle rolls when cornering.

I think you may have a possible solution to your quest in Lurk's post. All you need to do is scale up RC foam tyres, making sure that grip, durability, damping coefficient and thermal dissipation are also scaled appropriately.

[hardingfv32]

I have a honest belief that a suspension is only required because of track or surface irregularities.

Nothing bad about you guys proving me wrong.

I appreciate the tuning tools that you are discussing, but just pick one reason for an imbalance and expand on it.

As an example, I could see where the steering system could create an imbalance between tight and sweep type turns, but I am not sure that is always the case. I can also appreciate that the aero system is capable of generating an imbalance. As an example, does the performance ratio of the front and rear wings always very with speed?

Brian

[Jersey Tom]

This is basic, fundamental vehicle dynamics man. Read up on RCVD. Things aren't magically balanced by default. Front to rear balance of cornering stiffness coefficient for one. CS over load. One of the more basic balance metrics.

[hardingfv32]

"This is basic, fundamental vehicle dynamics man. Read up on RCVD. Things aren't magically balanced by default. Front to rear balance of cornering stiffness coefficient for one. CS over load. One of the more basic balance metrics."

You continue to miss the point of this discussion.

Removing the suspension automatically resolves your corner stiffness issue.

Brian

[Jersey Tom]

It absolutely does not.

[hardingfv32]

And why not? Are you going to suggest chassis stiffness next?

Would not chassis stiffness be linear and thus the load distribution linear? I don't see an unmanageable imbalance there.

Brian

[Jersey Tom]

Think you're just missing the fundamentals here. If you're going to raise these sort of questions and pose these statements and assertions, you should try to demonstrate that you understand the basic principles.

Handling balance has --- all to do with load transfer distribution being "linear" (presumably you mean with regard to the onset of lateral acceleration).

In the most simple pure cornering case (and clearly we're dealing here with examples so simple they border on asinine), your sublimit handling balance - USG at least - is defined by the front and rear cornering stiffness coefficients. The CSC's and USG are then a function of the instantaneous load distribution on the 4 corners of the car. With no suspension, and no way of adjusting that distribution, your balance is fixed and NOT necessarily neutral.

I suggest reading up on simple handling models - bicycle model, 4 corner rigid body dynamics models, sprung models - and revisit this thread later once you have a better understanding of what's important and what drives the 1st order effects.