Remote third spring

[Tim.Wright]

The first thing that sprung to my mind ...

I see what you did there

[DaveW]

Something like this...

Rather similar to mep's solution. I like the spring compensator, simpler than the alternatives (using Pascal's Law).

A couple of comments, the layout of your diagram appears to be reversed (top of the actuator appears to be connected to the front axle), and there appears to be an additional hydraulic pipe plumbed to the top of the actuator (running rearward).

[DaveW]

This provides both the interlinked levelling effect and increases the spring rate in pitch

Levelling is one effect, pitch spring rate is something else. I like to refer to the first as "quasi-static", and the second as "dynamic". The two are not necessarily the same.

Consider two cases:

1. To control the aero forces as speed increases, it is required that the system responds fast enough to maintain front & rear ride heights as the (average) down force changes. This is admittedly fairly fast in an F1 vehicle, but it is still "quasi-static". Demonstrably, levelling works, sometimes with an observable time delay.

2. To increase the effective spring rate, it is necessary to move fluid between the actuators fast enough to emulate the effect of higher rate springs. It is a fact that the emulation will fail at some speed (velocity/frequency), depending upon pipe diameter, line length, and any intervening devices. The pitch mode of an F1 vehicle has a frequency of around 9 Hz. In tests I have carried out on a similar system linking and blanking the system has had no measurable effect on pitch mode response. I concluded that effective dynamic spring rate is unchanged.

[scarbs]

This provides both the interlinked levelling effect and increases the spring rate in pitch

Levelling is one effect, pitch spring rate is something else. I like to refer to the first as "quasi-static", and the second as "dynamic". The two are not necessarily the same.

Consider two cases:

1. To control the aero forces as speed increases, it is required that the system responds fast enough to maintain front & rear ride heights as the (average) down force changes. This is admittedly fairly fast in an F1 vehicle, but it is still "quasi-static". Demonstrably, levelling works, sometimes with an observable time delay.

2. To increase the effective spring rate, it is necessary to move fluid between the actuators fast enough to emulate the effect of higher rate springs. It is a fact that the emulation will fail at some speed (velocity/frequency), depending upon pipe diameter, line length, and any intervening devices. The pitch mode of an F1 vehicle has a frequency of around 9 Hz. In tests I have carried out on a similar system linking and blanking the system has had no measurable effect on pitch mode response. I concluded that effective dynamic spring rate is unchanged.

I thought that was why they had two systems, the interlinking and the spring,for the two different effects

[xpensive]

Something like this...

http://scarbsf1.com/blog1/wp-content/up ... system.jpg

The more I look at this the more convinced I get that such a system could be problematic at acceleration, when it would generate negative pressure in the rear circuit, which is a no-no with hydraulics. Unless there is something I don't understand?

[mep]

It is preloaded so the pressure will always remain positive.

[marcush.]

it may well have a positive pressure through preload -but you are still "sucking " the fluid through the pipes at times -not good.

[xpensive]

It is preloaded so the pressure will always remain positive.

With the low compressibility of hydraulic oil, I can't see how a pre-load will make any difference when the rear heave is trying to suck yellow oil out of the cylinder against the coil spring's resistance, a miniscule movement and the pre-load is gone.

The oil will turn into gas at a certain underpressure. Think about it.

[mep]

Oh, I see what you mean now.
I think there should be an additional oil circuit which will make sure the oil is always pressurized.
Kind of a closed circuit but separated by the pistons in different chambers

[xpensive]

Don't think it matters mep, you can't use hydraulics for pulling, that's all there is to it really.

I still believe the image is a single acting cylinder with means to adjust the hydraulic volume and thus the front ride-height.

[PhillipM]

Something like this...

http://scarbsf1.com/blog1/wp-content/up ... system.jpg

The more I look at this the more convinced I get that such a system could be problematic at acceleration, when it would generate negative pressure in the rear circuit, which is a no-no with hydraulics. Unless there is something I don't understand?

It's drawn as connected with solid pistons in the dampers - in reality I'd be very surprised if that was the case, both for the reasons you mention, and the issue of the low speed damping being so high the car would jack up and down over the ripples in the braking area's.
It's much more likely it works like most other heave systems on racers where it acts on the rod area - you don't need a massive amount of force as you're supplementing the springing and damping that is already there, so the small shaft diameters and friction induced may not be much of an issue given the system will be designed to work mainly under brakes and high downforce when the loadings are at their highest anyway.
wrt to 'suction' that would stop the system from working - it's possible the system is preloaded with springs inside the dampers already working against the spring on the remote canister/valve block (they would be, in effect, always trying to lower the car)

[xpensive]

What we can see is a remote hydraulically operated spring, not a shockabsorber or damper in any which way.

[Tim.Wright]

What we can see is a remote hydraulically operated spring, not a shockabsorber or damper in any which way.

Why are you so convinced that they haven't incorporated a damper into that unit?

[xpensive]

I cannot be 100% certain that it doesn't hold a nuclear reactor to be honest, but I can't see it.

[Tim.Wright]

Well I think Dave could answer this best. In your experience Dave, with a typical 6 damper setup, are F1 cars over or under damped in pitch?

If they are overdamped, you could possibly put a pitch spring in without a damper. Otherwise adding a stiffness without a damping to control it wouldn't be a good idea considering the prime motivator for such a system aero platform stability.