Idea about a different approach to steering F1 car

[marcush.]

hi guys ,I would like to drop an idea in this forum I had this morning:
Imagine the usual steering linkage fixed to the tub structure -effectively reduced to toe links but fit the complete rest of the front suspension on a substructure inside the tub pushed sideways by steering action (with a hydraulic pump available that would be a feasible task even though at very low speeds(in the paddock..)the car would be obviously a dog)but with speed there would be the major advantage that you would be able to increase the half track of the outer wheel by quite a bit and have the less loaded inner wheel lose some track ...I´m aware that this would be quite a system with sliding piston/elaborate guiding to really optimise load paths but it would alter weight distribution favourable in corners ,wouldn´t it? To go one step further one could think of doing the same at the rear with the exception of not fixing the toe links rigidly to the chassis as
this would of course be 4 wheel steering...That cannot be allowed can it?
Any thoughts on this?

[mep]

Hi,
maybe a quick drawing (on paper and scanned) would help to understand this. I got a very rough idea what you want to do but I don't really get what you want to have fixed and where. How the actual steering should work is also not clear.
Sorry.

[thisisatest]

First Post!

If I understand you correctly, one could achieve the same thing by offsetting the axle from the kingpin centerline (or steering axis). If the axle was behind the steering axis, then when turning LEFT, the RIGHT wheel would swing to the RIGHT.
there are a few reasons to not want to do this, primarily the steering effort could get very high. Increasing caster has a similar effect on steering effort, btw, and I've wondered why some cars don't move the front axle FORWARD relative to the steering axis to be able to run more caster without increasing steering effort too much.

If i'm way off base, please take it easy on me, being new here n all.
Thanks,

[747heavy]

I could see some difficulties in the way, we want to provide (force)feedback to the driver. Not sure, if you system would transmit the self-alingment moment of the tyre in the same way, as a conventional steering system does.

This may requirers a "re-learning" process for the driver, in the way as SAAB tried with their joystick steering for a road car.

I think it would be possible, not sure if it is practical.
Dealing with the friction/stickion forces of the system, espically under heavy braking and combined load conditions, could be tricky.
It would also lead to an offset in the way the braking force is acting onto the chassis, leading to some self-steering effects (increasing understeer IMO).

[marcush.]

One real concern is the reaction of the whole system to the sideforces in cornering as of course the grip of the tyre would make the tyre stick and some remarkable force would be needed to not push the tub towards the outside of the corner... so it would be something quite more severe than self aligning torque produced by caster or trail..

Again for clarification mep:

Imagine the whole suspension system mounted to a subframe that has a degree of freedom in Y direction of the car only .This would be actuated by the steering mechanism /hydraulics.

To steer the car you need to just have the steering linkage fixed to the main tub ,NOT connected to the steering mechanism.By displacing the sliding subframe left/right the front Uprights would svivel and you´d get steering lock ...


747h: at the rear the driver feels the limits of adhesion as well ...some drivers referring this to the rear wandering ...and letting go misinterpreting the onset of tyre going in slipangle as a oversteer condition wrongly.So to my mind this should be the same reaction in the front no matter if you got loads of caster trail or whatever (which does amplify the feedback on the steering ).In my book the force feedback is not really a steering thing but a slipangle thing.

In effect my idea would need a lot of hydraulic power input to enable the driver to hold the car in line (as the steering would see the complete cornering side force!).So there would be substantial selfalignment force available with rising
cornering force reducing with diminishing gs...right?So maybe the steering reactions out of zero steering position would be violent but with building up sideforce you would need to really hang in the steering to not go straight (understeer)..So maybe my idea would be very tricky to go straight ..

[tuj]

So if I understand this, would the uprights actually be moving sideways in relation to the chassis?

[marcush.]

Yes indeed.the steering would be performed by moving the uprights in Y-direction .
I´m not even positive if this was even legal (maybe it´s a bit like the lotus double chassis..it depends on your viewpoint).

[machin]

Interesting.. If you assume the chassis stays still the tyre contact patches would need to move laterally...

If you assume the tyre contact patches stay still then the chassis needs to move laterally...

[marcush.]

it is like you are positioning your CoG and CoP inboard ...
The effect is bigger with steering angle so the aero influence due to tyre movement would be highest with large steering angle .....

[thisisatest]

i still don't see how this is any different than keeping the wishbones stationary and moving the axles to the steering rods, (and moving the steering rack to behind the suspension).
seems easier.

[Belatti]

If I got you right, using this system in both axis you are trying to use the chassis as moveable ballast.

Then I can only think about a Lotus T88-like twin chasis car with the added feature that one of those chasis has a controlled extra degree of freedom in Y.

[marcush.]

If I got you right, using this system in both axis you are trying to use the chassis as moveable ballast.

Then I can only think about a Lotus T88-like twin chasis car with the added feature that one of those chasis has a controlled extra degree of freedom in Y.

You got the message and of course the implication of doing so .So to do that for the front might be debatable but as soon as you do this y-movement at the rear the car is movable ballast as you said.
The one thing at the rear you could do legally is to design the inboard mounts flexible and extending in length under load ! nice challenge..

[riff_raff]

marcush,

I believe the F1 reg's require suspension symmetry side-to-side.

Asymmetric suspensions are commonly used in other forms of racing though, and have been for many years. Take a look at this old Indy car chassis:



riff_raff

[marcush.]

riff ..I´m aware of this .But my idea is syymetrical in a straight ahead steering position and so at least at the front I see no real difference to a conventional
steering layout.
It mainly is a question of what you call suspepension and steering ..
At the rear I think you are correct movable suspension points should not be within regs...even if you could debate elastokinematics if you could design something that worked .
.. very cool pic of the sidewinder ..I saw this in Indianapolis on display a decade ago ...unfortunatelly it was only looking spectacular ...

[The_Man]

This idea has gotten me thinking a lot. Just to make things clear before I comment this is my interpretation of what you are trying to propose:
The steering linkages are attached to the tub and the the entire nose of the vehicle is steered to perform the steering action.

So dynamically there seems to be a problem with chassis rigidity. A dynamical model of this type of steering would be a bicycle model basically with the main chassis split into 2 parts and the input in the form of the angle between the 2 parts of the chassis instead of the steering angle of the steered wheel(I have worked it out on a piece of paper but too lazy to actually find a scanner). This way it is not much different from the conventional set-up. But the assumption is that the input is a angle(displacement) input. This means that is the input is constant the chassis is stiff. But this is not true because we have to see the forces involved. Since this input DOF is splitting the chassis the. rigidity is compromised. The force that the actuator produces will be equal to the top view bending moment that will be present in the chassis. So basically the strength of the actuator will determine the chassis stiffness. The Actuator will be heavy and consume a lot of power. Moreover the stiffness that the actuator provides will not be comparable to the solid chassis stiffness and the response to steering will be quite sluggish and will be massively understeer.