Raptor22 wrote:bhallg2k wrote:scarbs wrote:I understand Mercury is banned. The interlinked suspension proposed by AdudaliaF1 based along the 1960's Austin Hydrolastic system, has been used in F1 since 2009! and is in use by over four teams currently. I have knowledge ot two teams that were workng on it in 2011.
(That nullifies everything I've said on the subject, but at least it's closure. Hopefully.)
I didn't think mercury would be allowed but good to see that the my views on the LoRDISM (Load Re-Distribution Interlinked Suspension Mechanism) has been vindicated.
It´s a little bit more, then just a "Hydrolastic" system, because a classical "Hydrolastic" system, will need suspension movement to work (oil get´s displaced in one damper/cylinder, which creates a pressure, which then get´s used to move another damper (normally diagonal linked, but other combinations are possible).
The net effect, is that you keep the sprung part of the car (chassis)leveled in relation, to the unsprung part (tyres/wheels).
That works very well and efficient in cars that derive most of their reaction to road inputs from the suspension. In a road car the relation of tyre stiffness to suspension stiffness is anywhere from ~1/10 to 1/6. Which means that the tyre is 10-6 times stiffer, then the suspension, so for every mm deflection of the tyre, you will see 6-10 mm deflection from the suspension.
In F1, due to their tyre dimensions, the relation is somewhere around 1/1 at the best of times and often the tyre will be "softer/vertical less stiff" then the suspension, especially at the front under the conditions in question [fully aero loaded car, braking hard] it get´s to the point, that almost all the deflection comes from the tyre. [plus perhaps some structural deflection, compliance from the suspension]
A normal "Hydrolastic" suspension, can´t compensate, for this condition (tyre deflection), because it works based on suspension deflection.
This is where the beauty of the Mercury system lays.
The "Mercury" or any other mass you want to use, acting against a small piston, will provide a pressure in response to longitudinal acceleration (making use of the inertia effect), the same effect, that causes the tyre to deflect in the first place.
And it does so, independent of any suspension movement.
You could call it´s function a "fluidic amplifier", you need this "amplification effect" to combat the deflection of the tyre, a "normal Hydrolastic suspension" will not do this.
What Lotus-Renault, and other teams are trying to create is a system which acts like a "inverse spring", a system, which extents something, and does so more, as more load you put onto it.
If you would see it from a classical spring stiffness point of view, you would need a spring with "negative/inverse stiffness" in your system, to compensate for the deflection of your other spring (the tyre). [the tyre and the suspension, will form two springs in series, where the combined spring rate is smaller then the smallest individual spring rate Kcom = 1/(1/Kt)+(1/Ks)]
There are different means to the end, Lotus-Renault wanted to use brake torque, which makes use of the "Inertia" of the complete car x the %age front brake distribution, and the Mercury or similar systems making use of another "mass inertia", be it the mass of the mercury, or a Tungsten block.
Locking out the suspension, what teams do since forever under these conditions, will not get you the effect you would like to have, because even if you have infinite stiffness in your suspension, you still have the deflection of the tyre. Which will be around 3-5mm in the hard braking event.
That may does not sound a lot, but if we assume a front ride height of ~30mm, you lose 10-16% of your total ride height, just in the braking event.
If you find a way, to eliminate this additional loss, you can run your car 10-16% lower for the rest of the time, which is not nothing in an aero car, such as F1.
The beauty of the Mercury system, is it´s simplicity and ease of packaging, but you can generate the same effect by other means, the system is just a bit heavier and a bit more difficult to package, but you get the same effect out of it.
You can combine the "fluid amplifier" unit with a more conventional interlinked suspension like "Hydrolastic" or "Kinetic" or other systems, which work along the same lines, and use there individual merits under other conditions, like roll etc. - best of two worlds if you like.
It get´s quickly fairly complex, and is maybe not so easy to set-up & understand at first, but the benefits would be worth the hassle, if you manage to make it work and understand all of the implications.