Ride adjusting suspension?

[ForMuLaOne]

Is it allowed to place the fuel tank in a way that it stands on a hydraulical plate? When the tank is full, the weight pushes the suspension up, when it becomes empty, less weight is applied on the plate and the car lowers itself. It is passive i guess, and something lotus might deal with.

[Richard]

No. Suspension travel is only allowed to be changed by forces acting on the wheels.

[Kiril Varbanov]

Excerpt from the regulations:

10.2 Suspension geometry :

10.2.1 With the steering wheel fixed, the position of each wheel centre and the orientation of its
rotation axis must be completely and uniquely defined by a function of its principally
vertical suspension travel, save only for the effects of reasonable compliance which does
not intentionally provide further degrees of freedom.

10.2.2 Any powered device which is capable of altering the configuration or affecting the
performance of any part of the suspension system is forbidden.

10.2.3 No adjustment may be made to the suspension system while the car is in motion

[allstaruk08]

10.2.3 No adjustment may be made to the suspension system while the car is in motion

maybe you dont adjust the suspension, you adjust what the suspension is mounted to?

[ForMuLaOne]

Well, then this system could adjust the delta in pressure, caused by a lighter tank, when the car stands still. Pit Stop for example. Car comes in, the actuator now provides less pressure, a valve opens and equals this delta, the hydraulic suspension parts become lowered.

[ForMuLaOne]

No. Suspension travel is only allowed to be changed by forces acting on the wheels.

The circumstances as explained in my post above, are also given. The forces are all acting on the wheels, because the suspension parts which are connectet to the wheels "pump" up the fuel tank, the tank is "over the top when its empty and the car is lowered. When the car gets fueled, the mass inside the tank pushes down the car, but the effect is equalised by transferring the higher hydraulic pressure to the suspension`s hydraulics. In this way, you reverse the normal change in rideheight. If the rule was taken serious, cars were not allowed to become lighter, as the suspension travel clearly changes when the car becomes lighter.

[CBeck113]

No. Suspension travel is only allowed to be changed by forces acting on the wheels.

The circumstances as explained in my post above, are also given. The forces are all acting on the wheels, because the suspension parts which are connectet to the wheels "pump" up the fuel tank, the tank is "over the top when its empty and the car is lowered. When the car gets fueled, the mass inside the tank pushes down the car, but the effect is equalised by transferring the higher hydraulic pressure to the suspension`s hydraulics. In this way, you reverse the normal change in rideheight. If the rule was taken serious, cars were not allowed to become lighter, as the suspension travel clearly changes when the car becomes lighter.

My $0.02, please correct me if I have any errors in here.
You're both right : gravity is the force which acts on the suspension (otherwise the suspension would not be necessary) and therefore on the wheels. If the adjustment is done in the pits then the only question is if the system can be made so simple that the adjustment can be done quickly, and the additional weight of this system doesn't eliminate the advantage (which I highly doubt). If something like this can be done during the race, then only under the premise that the weight drop is the force reduction causing the ride height change, i.e. negative force. The mechanically / hydraulically active suspension from Mercedes (and others) would offer the mechanism to reduce the ride height during the pit stop, since there must be one point for the necessary adjustments.
But, even if this is according to the rules, the final judgement is in Charlie's (no, the other one ) hands, if the "spirit of the rules" are being followed.

[Richard]

I didn’t have the regs when I posted my earlier comment, here’s the exact wording:

The suspension system must be so arranged that its response results only from changes in load applied to the wheels.

The test for clause 10.1.2 is simple:

- Imagine holding the car chassis off the ground
- Apply loads to the wheels, push them, pull them, twist them, etc
- All that suspension response is legal.
- Any suspension travel caused by any other force (such as a hydraulic or mechanical force derived from the weight of the fuel or ballast etc) is illegal.

Also the stewards are likely to interpret the hydraulic or mechanical input from the weight of the fuel tank as a powered device, falling foul of 10.2.2 quoted by Kirirl above.

[ForMuLaOne]

I didn’t have the regs when I posted my earlier comment, here’s the exact wording:

The suspension system must be so arranged that its response results only from changes in load applied to the wheels.

The test for clause 10.1.2 is simple:

- Imagine holding the car chassis off the ground
- Apply loads to the wheels, push them, pull them, twist them, etc
- All that suspension response is legal.
- Any suspension travel caused by any other force (such as a hydraulic or mechanical force derived from the weight of the fuel or ballast etc) is illegal.

Also the stewards are likely to interpret the hydraulic or mechanical input from the weight of the fuel tank as a powered device, falling foul of 10.2.2 quoted by Kirirl above.

10.1.2

-Holding the chassis off the ground: No change in this state, suspension stays in it`s position. Not Position, but preloads applied to the system is defined an changes in respect of the fuel level, which is the same on a car where you deal with different "preloaded" springs. Therefore legal.

- There are no other forces applied than the same forces that are applied on the wheels under normal circumstances. Normal circumstances mean: The car ( standing at the ground again) will move upwards, if the weightforces of the fuel become less due to consumption. Therefore we speak of a system that does not force the system to change, but the system changes because given forces decrease. We are talking about the opposite effect of the same thing by opening the regulating hydraulic circle WITHOUT dealing with any other forces than the ones which are applied on it anyway.

10.2.2

- The Input of the weightforce of fuel on the suspension system stays the same, but there is a switch which negates or compensates forces. The effect can be seen in the effect that there will be NO change in positions of suspension parts, when the car stands on the ground. A fact that is also given when the car is up in the air, as the maximum load of the fuel tank and therefore rideheight can be limited and the empty tank will also not lead to a position change of the cars suspension parts, as the preloads are still high enough to keep them in the position which offers the highest rideheight.


If you forbid such a system, you also needed to limitate or forbid the ability of the cars suspension to lift it up because of the preloads of the springs. This is not the case in the latest rules. They allow this effect as a normal consequence.


EDIT: The arguments conclude, that there is no response by definition, but a different precondition of the suspension. So the basis for responses is changed, but no response was given yet.

[autogyro]

Such a system does not alter the suspension 'travel'.
In fact, because it maintains the same ride height it also maintains clearances and this allows the 'travel' to be the same.

[Maxion]

I'd like to remind everyone that the technical regulations are black and white. Either you comply with them, or you don't.

Technical regulations 2013, 10.1.2

The suspension system must be so arranged that its response results only from changes in
load applied to the wheels.

Technically having the fuel tank hydraulically mounted does comply with 10.1.2, since when the fuel tank empties the load on the wheels decreases due to the decreased weight of the car. The regulations do not explain what they mean by load, they don't specify that it has to be a load from outside of the car.

EDIT: Neither does the rule specify that it has to be a direct load to the wheels.

[ForMuLaOne]

I'd like to remind everyone that the technical regulations are black and white. Either you comply with them, or you don't.

Technical regulations 2013, 10.1.2

The suspension system must be so arranged that its response results only from changes in
load applied to the wheels.

Technically having the fuel tank hydraulically mounted does comply with 10.1.2, since when the fuel tank empties the load on the wheels decreases due to the decreased weight of the car. The regulations do not explain what they mean by load, they don't specify that it has to be a load from outside of the car.

EDIT: Neither does the rule specify that it has to be a direct load to the wheels.

Right, what do you think, would such a system be legal or not?

[Maxion]

Right, what do you think, would such a system be legal or not?

The system as discussed here produces an indirect load on the wheels via the weight of the fuel which is used to produce a response in the suspension.

I'd say it goes against the spirit of the rule, but adheres to it's wording, making it legal. If it's found out that they're running such a system (if they even are !) then the FIA will probably issue a technical directive to make it illegal

EDIT: Richard_leeds argues that it could be illegal due to it being considered a powered device, but I doubt it, as this system isn't powered a power source. All other mentions in the technical regulations about power or powered devices refer to anything using a power source to work.

[Richard]

If adding fuel changes the preload then that is adjusting the suspension . There is a rule that suspension can only be adjusted from outside the car with a tool. I think it is one of those unpublished directives, RB fell foul of it last year.

Holding the car in the air is conceptual way to isolate external forces. The rules say that the suspension should have zero response in that state. Adding and removing things in the car, flicking switches, applying brake pedals, running the engine, and anything else you can think of should not trigger any response in the suspension. The proposed method in the OP will result in a changed response in the suspension, hence it is illegal.

Right, what do you think, would such a system be legal or not?

Indeed, the reality is that Charlie would ban it regardless. Probably under the catch all rule of adjustable aero (like the TMD and the Lotus ride height braking gizmo), or he might say it is a powered device. Either way it isn't going to happen.

[Maxion]

If adding fuel changes the preload then that is adjusting the suspension . There is a rule that suspension can only be adjusted from outside the car with a tool. I think it is one of those unpublished directives, RB fell foul of it last year.

Holding the car in the air is conceptual way to isolate external forces. The rules say that the suspension should have zero response in that state.

That's not in the technical regulations though, they don't specify a testing procedure for the cars suspension.

Indeed, the reality is that Charlie would ban it regardless. Probably under the catch all rule of adjustable aero (like the TMD and the Lotus ride height braking gizmo), or he might say it is a powered device. Either way it isn't going to happen.

Yep, I doubt any team would actually develop such a system all the way to race-ready without first asking about the legality of it. If such a system were found on a car it'd most certainly be made illegal quite quickly.