Ride Height: Altering between Q and Race

McLarens Martin Whitmarsh spoke out at the Australian GP about the use of Ride Height Adjustments in between the qualifying and the race. Suggesting that several teams, one of which was Red Bull had such systems.
 
As I have previously explained ( http://scarbsf1.wordpress.com/2010/02/21/ride-height-changes-with-fuel-level/ ) the ban on refuelling creates huge weight differences between qualifying and the race (150kg), this alters ride height considerably (by F1 standards). Already running just 20-30mm off the ground the cars aerodynamics relies on a low ride height to create maximum downforce.  Equally having the ride too low height creates wear on the cars underbody skid-blocks set into the ‘plank’, if the wear is excessive the car will be excluded from the results. Furthermore Parc Fermé rule prevents the teams changing settings in between qualifying and the race, so teams need to find a compromise somewhere between set up for the light Q fuel or heavy race fuel. However, if a team were able to find a way to alter the ride height legally in between or indeed through the race then they could have ideal set up for each segment of the weekend. We know teams have ride height adjusters that can be adjusted at the pit stop, these tend not be used as they cannot be used until the first pit stop and with only one stop being the nor for the opening races it appears to be a ‘set up’ complication no one wants.   
 
 
Suspension set up

F1 cars suspension tends to adopt similar formats both front & rear and across the teams. Ride height and spring\damping is provided by a pushrod (or Pull rod for Red Bulls rear suspension, which is the same but inverted) which operates a rocker, this rocker has levers operating the torsion bar spring, damper and third (or heave) damper. Ride height it set by the angle of the torsion bar on its splines and fine tuned by the shims in the pushrod.  Ride height does get controlled by the heave damper, but only when high aero loads compress the suspension at high speed, as the heave damper has some free travel before it starts to add stiffen the suspension it cant be used for adjusting static ride height. The individual wheel dampers do apply some pressure to the suspension when at rest, but aren’t commonly used for setting ride height. 

Mechanical solution

One solution put forward was a ratcheted system that keeps the ride height artificially low with a light suspension load and unlocks when the car is more heavily fuelled. I find this harder to believe as the suspension sees huge variance in load around the course of a lap, how it would identify the peak loads as being a heavy fuel load compared to say a bump makes the system hard to predict. Unless a solution that demands a suspension attitude that cannot be seen on track, such as raising both wheels to compress the heave damper car beyond normal limits to release a mechanism, this could possibly be done legally in the pit garage with the FIA’s knowledge. 
 
 
Repressurisation 
 
Another solution that seems altogether more feasible is the use of the gas charging cylinder within the damper. this cylinder normally acts to offset the motion of the damper rod inside the damper body. Charged with nitrogen, this does create some preload inside the damper. Teams are apparently allowed to recharge the nitrogen cylinder in Parc Fermé.  Its believed that if the team were able to over-pressurize the unit after qualifying with a low pressure, it would lengthen the damper, raise the ride height in order to offset the race fuel load.
One additional scenario with this set up, is the gas cylinder could be set up with a bleed valve, to allow a slow controlled pressure loss.  This would allow the suspension to lower through the race and the fuel is burned off. 
On paper this appears to be a perfect solution to the problem. 
 
 
 
 Cooling
One further theory is that the dampers are sensitive to temperature, for example cooler dampers could provide a lower ride height. Its possible to envisage a case where teams chill their dampers, again possibly the gas cylinder to reduce the volume of the gas to shorten the dmaper and lower the ride height before qualifying.  Then as the unit returns to ambient temperature the pressure increases and raises the ride height ready for the race. 
 
Over the course fo the Malaysian GP, we can expect to hear a lot of fuss about whether these solutions are being used.
However the potential of changing ride height for just the critical 3mm difference in between Q and the Race remains a technical challenge, but one well worth exploiting.
It is rumoured there are three possible solutions, although there may be more we have not heard of.
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21 thoughts on “Ride Height: Altering between Q and Race

  1. Scarbs,

    great insight into the possibilities.

    I don’t believe the third option would work well (heating/cooling) as the cooled damper would induce a lower ride height and lengthen as it warms. This suggests the damper would stay at the higher position throughout the race and with the lighter fuel load towards the end, increase ride height even more due to a lower weight of the car.

  2. What about some sort of lever arrangement between the fuel cell and chassis? It should be possible to arrange some sort of cantilever in the cell mountings to transmit force, perhaps via steel cables to the suspension. Then as the fuel cell loses mass the tension on the cables would change and lower the ride height. If you were to heavily damp the levers thenthey would not react to bumps and undulations.

    That’s how I’d do it.
    Craig.

    • That was my line of thought too, but I don’t know the rulebook, so a semi-mobile fuel cell may be illegal to start with.

      The advantage of this approach would be a suspension adjustment directly proportional to fuel usage.

      Disadvantage is that I think this would be illegal on 2 counts:
      > active suspension (i.e. suspension adjustment while in motion)
      > active aero (more of an active aero device than a mass damper, and probably equal to the flexi-floors in this regard)

      Another thought though along the lines of the repressurisation mechanism.

      Correct me if I’m wrong, but aren’t the cars out of Parc Ferme on the formation lap? If so, would it not be legal for the driver to press a repressurise button meaning the other teams have less chance of spotting it.

      On the point of the pressure required to change the ride height; I’d guess (as a relative layman) it might be worthwhile using the pressure to move the mount point to change the angle of the suspension arms. Should be sustainable at a lower pressure that way….
      (Passive bleed mechanism would apply, but isn’t that active aero too???)

      • Your ideas are all technically valid, but a legal nightmare. The semi-mobile fuel cell idea sounds postitively illegal..! It would’nt be legal for the driver to press a repressurise button, except at the first pit stop. So thats of limited benefit, to do it before or while the car is moving is clearly illegal. To do anything with suspension geometry is also strictly illegal.

        This is what makes the whole notion of an adjustable ride height fraught with problems….

      • The repressurise button idea was for on the grid, between the formation lap and light procedure, while stationary.

      • Interesting, could “it” be programed into the launch sequence?

        Legally, if the ride hide adjustment occurred after the lights went out, but microseconds before the car starts to move, would it then be legal, since Parc Ferme would have ended?

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  4. Pressurizing the shocks will not work. Remember the pressure is almost equal on each side of the shock piston, EXCEPT for that that area represented by the cross section of the shaft. So for say a .5″ shaft @ 300 psi you get 59 lb. of force.

    Current shock designs employe very low pressures, 20-30 psi.

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  6. With regards to the temperature change idea, would it not be possible to have the dampers temperature controlled by heat from the engine? I.e. At the start of the race, engine heat raises the temperature causing the dampers to extend. Then as the race progresses, the amount of heat reaching the dampers is lowered, thus lowering the ride height. This could possibly be controlled by the driver altering a vane that varies the amount of air flowing around the car to chill them.

    During qualifying the vane could be fully open, allowing the air to cool the dampers too the maximum, allowing the ride height to be at it’s lowest setting.

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  8. I’m thinking everyone’s over-thinking.

    Not sure how regulated the damper construction is, but it struck me last week that (assuming there’s no ruling against it & ).

    “Custard Dampers”
    —————–
    (stick with me on this – it’s not totally insane!)

    A 2 stage damper:

    1st stage=standard spring/damper (ride)
    2nd stage=custard damper (ride height)

    The “custard damper” contains a non-Newtonian fluid (like instant custard – hence the name).

    Resistance of the fluid is proportional to the pressure applied. The force exerted on the fluid will drop as fuel burns off (nothing abnormal there). The fluid being custard however, the resistance offered will reduce until the point where the container volume reduces sufficiently that the pressure is equalised to the critical level, effectively reducing rideheaight in it’s adjustment to the new load.

    – As fuel burns off, the ride height is reduced…

    (just a brainwave – feel free to pick holes)

    Notes:
    ——
    The custard damper must be sprung (relatively weakly) to allow ridehight recovery between Qually and race and not under aero load.

    As the majority of load absent until in motion & with the standard spring/damper smoothing the bumps, the [relatively] weakly sprung damper should hold up until the non-Newtonian effects take over under load.

    Setup would be relatively knife-edge with instant custard, but then that’s often the norm in high-end motorsport.
    Particularly setting avoiding inadvertent rideheight changes under differing loads around a lap, though low rideheaght for ground-effect should be more critical in high aero load in highspeed corners, so setup could target those conditions.

    The “custard effect” could of course be achieved with some valve system that chokes/closes off based on the pressure exerted, which would be more tunable, but is a bit more than I can design without putting pen to paper.

  9. I’m surprised you haven’t mentioned a Nivomat system. This uses a valve in the damper that maintains a constant ride height. Requires no external input, hence complies with the suspension regs.

    • I’m aware of the Nivomat solution, I didn’t include it because I hadn’t heard that it was beign used as a solution to the the F1 issue.
      I am now hearing teams aren’t usign the solutions I pointed out, but a load\position sensitive spring inside the heave damper. I have some explanations from suspension specialists, but I need to read them through to be sure I fully understand them before I explain them here.
      This would explain how Red Bull are confident their system is legal, while McLaren may have been ‘barking up the wrong tree’ with their planned solution.

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