F1 2010: Ride height adjustments during pit stops

[autogyro]

Thanks tok-tokia, that should get the detracters and the American racers reviewing their educations.
Perhaps we should go into NASCA and start winning some races?

[marcush.]

Thanks tok-tokia, that should get the detracters and the American racers reviewing their educations.
Perhaps we should go into NASCA and start winning some races?

=D>

arrogance as we have seen here as well does not necessarily make your car faster ,but at least looking into things and questioning them till you find the limitation will..

my one remaining question is :would that system allow for wanted attidude changes?

[autogyro]

Thanks tok-tokia, that should get the detracters and the American racers reviewing their educations.
Perhaps we should go into NASCA and start winning some races?

=D>

arrogance as we have seen here as well does not necessarily make your car faster ,but at least looking into things and questioning them till you find the limitation will..

my one remaining question is :would that system allow for wanted attidude changes?

Sorry Marcush, just a response to the humour and point taken.
Attitude changes could be handled partly by a linked for and aft and side to side system of hydrolics, however the conventional spring/torsion bar secondary part of the system could be sufficient for this task and the primary used just for ride height. Depends on the weight/space trade off.
Sorry I added this:
Because the hydro/gas system is self levelling and not subject to load geometry changes but controls them, it can be used to move the suspension in the reverse direction to that expected by input forces. This was considered in the old days of skirt DF and twin chassis development. There are countless posibilities.

[DaveW]

I know the crude one-way type dampers were how NASCAR teams were doing it a few years ago, and then NASCAR started handing out mandatory spec dampers and regulating spring rates, etc. If they have some other trick setup now then I'm interested. Do you have any info that's more specific about work-arounds for the static ride height rules? I'm not asking for detailed damper schematics, but I am intersted in any general functional description beyond "more sophisticated".

Also, yes I understand that max aero load in F1 is much greater than full fuel load. I don't understand where that comment was supposed to lead me.

Difficult to answer your question simply.

Suppose the spring(s) on a "corner" result in a rising rate characteristic (i.e. the average rate will vary with the average load). A sudden load reduction from any equilibrium condition, will cause the suspension to extend at a rate (speed) that will depend primarily upon the (current) spring rate and the (rebound) damper strength. The lower the mean supporting load, the lower the effective spring rate and the lower the extension speed even when the rebound damping is linear. The effect can be exaggerated by making the rebound "style" of the damper digressive (damping coefficient increases with decreasing velocity).

I hope the above "thought experiment" is sufficient for you to accept that a damper with a given bump/rebound damping ratio & digressive rebound style working with a rising rate spring will tend to make the suspension "jack" towards a fixed position, regardless of the applied load. The spring rate variation & damping style can be "tuned" to make the average dynamic position relatively independent of the mean load reacted by the suspension.

In the NASCAR case (pre COT), the effective spring was/is the coil spring working in series with vehicle structural compliance (bump rubbers not allowed) &, whilst the dampers are heavily rebound biased, they do have bump damping. "Tuning" includes manipulating the vehicle installation stiffness. Bump rubbers, bellevilles, etc. are used in F1.

[BreezyRacer]

Professor posted a link that describes the Nivomat self levelling shock.

Here is another (longer)description of it: http://www.roversd1.info/misc/suspension.html


This diagram from that link shows how the stroke remains the same despite load, not just the amplitude of the stroke but also the position that the stroke operates from. It is self contained and can hardly be said to be active suspension.

Taken directly from the website (rather than some pretty graph that shows nothing about how it works BTW)

"The level control with the Nivomat is usually carried out at the rear axle and can only be performed while driving because the internal pump is operated by the relative movements between the body and the axle caused by road irregularities. However, the Nivomat does not dropimmediately as soon as the vehicle stops but, due to its internal tightness, it can maintain the level reached for a longer period."

So let me get this straight .. even though the system uses a pump to control hide height it is NOT active suspension? Think what you will .. Charlie Whiting will probably have a different opinion, and his is the one that counts.

[Richard]

So let me get this straight .. even though the system uses a pump to control hide height it is NOT active suspension? Think what you will .. Charlie Whiting will probably have a different opinion, and his is the one that counts.

The rules do NOT ban "active" suspension. The wording is:

10.1 Sprung suspension :

10.1.1 Cars must be fitted with sprung suspension.

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

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.

The systems discussed here all comply with that rule.

I think the "pump" referred to in the Nivomat description refers to the action of a piston being forced through a cylinder causing the suspension fluid to move from one chamber to another. Just like the piston in a conventional damper causes fluid to move from one chamber to another.

[autogyro]

Same with any gas under pressure, no different than a shock absorber.

[BreezyRacer]

God knows I'm no lawyer but ..

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.

looks pretty damning to me. A shared gas charge is power that alters the configuration IMO.

Frankly though, let's all admit that this is a purely technical argument at this point. There's no way they are doing this, and there's no way IF they were doing it, they could hide it. Who would make these dampeners? How would you hide the plumbing from inspectors, even in just casual safety inspections, much less scrutineering after the races.

I admit it's a little fun to kick these ideas around. But it's far more likely that they are just increasing the gas charge of the dampeners in parc ferme, as they are entitled to do.

[marcush.]

God knows I'm no lawyer but ..

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.

looks pretty damning to me. A shared gas charge is power that alters the configuration IMO.

Frankly though, let's all admit that this is a purely technical argument at this point. There's no way they are doing this, and there's no way IF they were doing it, they could hide it. Who would make these dampeners? How would you hide the plumbing from inspectors, even in just casual safety inspections, much less scrutineering after the races.

I admit it's a little fun to kick these ideas around. But it's far more likely that they are just increasing the gas charge of the dampeners in parc ferme, as they are entitled to do.

this is not out of reach for the teams .they all have their own hydraulic specialists and some are doing their own dampers anyways.
It certainly is not out of reach for the damper specialists and can be done in aways you will never ever had a clue how it was done.
As things stand we have no chance to even see current dampers as the apertures are
small if at all you get a glimpse of a heave or J-damper at the rear..
I think the question for clarification from Brawn side is aimed directly towards
Fia taking a closer look at the Red Bull ...and if that is deemed illegal we will very soon know what they did..

and maybe the solution is completely different to what we think ...

[bill shoe]

I know the crude one-way type dampers were how NASCAR teams were doing it a few years ago, and then NASCAR started handing out mandatory spec dampers and regulating spring rates, etc. If they have some other trick setup now then I'm interested. Do you have any info that's more specific about work-arounds for the static ride height rules? I'm not asking for detailed damper schematics, but I am intersted in any general functional description beyond "more sophisticated".

Also, yes I understand that max aero load in F1 is much greater than full fuel load. I don't understand where that comment was supposed to lead me.

Difficult to answer your question simply.

Suppose the spring(s) on a "corner" result in a rising rate characteristic (i.e. the average rate will vary with the average load). A sudden load reduction from any equilibrium condition, will cause the suspension to extend at a rate (speed) that will depend primarily upon the (current) spring rate and the (rebound) damper strength. The lower the mean supporting load, the lower the effective spring rate and the lower the extension speed even when the rebound damping is linear. The effect can be exaggerated by making the rebound "style" of the damper digressive (damping coefficient increases with decreasing velocity).

I hope the above "thought experiment" is sufficient for you to accept that a damper with a given bump/rebound damping ratio & digressive rebound style working with a rising rate spring will tend to make the suspension "jack" towards a fixed position, regardless of the applied load. The spring rate variation & damping style can be "tuned" to make the average dynamic position relatively independent of the mean load reacted by the suspension.

In the NASCAR case (pre COT), the effective spring was/is the coil spring working in series with vehicle structural compliance (bump rubbers not allowed) &, whilst the dampers are heavily rebound biased, they do have bump damping. "Tuning" includes manipulating the vehicle installation stiffness. Bump rubbers, bellevilles, etc. are used in F1.

DaveW,

Bear with me. Your response was excellent. I think I understand what you're saying.

When the car is moving, the rebound-biased shock will pull a corner down (compress the suspension) until it's balanced out by the total spring load. The engineer will try to choose this dynamic suspension position at each corner to optimize overall aero performance.

At Daytona, the optimum aero situation is probably to run the car as low as possible at all corners to minimize drag. At other tracks the optimum aero strategy might be to run the front low and the rear high to maximize downforce. I'm guessing here, but I think this is the general idea...

However, keeping the range of dynamic suspension position tight at each corner requires spring and shock rates that are not optimum for mechanical grip. Compromises have to be made. You mentioned digressive rebound and chassis compliance. These are ways of improving mechanical grip within the context of tight ride height control.

Am I understanding this correctly? Here's my overall perspective-

If you need to control running ride height (due to changing fuel load or due to static ride height rules) then the best (non-active) approach is a Nivomat-type damper in series with a conventional spring/damper. The Nivomat-type thingie provides long-run ride height control and the conventional unit provides optimum spring and damper rates. If you are an F1 engineer you are done. If you are a NASCAR engineer you can't use the magic bullet that separates ride-height control from other functions. You have to make tradeoffs. You have to think of clever new ways to expand the envelope of tradeoffs.

Roughly, F1 has better suspension and NASCAR has more clever engineers. At any rate, I agree that NASCAR suspension setup is more sophisticated than I was suggesting in previous posts. Again, I appreciate your functional response.

[ringo]

How sensitive is the Novamat damper to static loads? and how does it differentiate between aerodynamic load and vehicle weight. Considering it was made for vehicles like SUVs which have no such thing as aerodynamic loading.

Can someone explain in simple logical terms how this thing responds?
I find it interesting that on low fuel the car is leveled down, then goes to parc ferm untroubled, then fueled for the race and it magically pushes back and increase the shock length to compensate for the weight, without any interference from the mechanics.

[bill shoe]

How sensitive is the Novamat damper to static loads? and how does it differentiate between aerodynamic load and vehicle weight. Considering it was made for vehicles like SUVs which have no such thing as aerodynamic loading.

Can someone explain in simple logical terms how this thing responds?
I find it interesting that on low fuel the car is leveled down, then goes to parc ferm untroubled, then fueled for the race and it magically pushes back and increase the shock length to compensate for the weight, without any interference from the mechanics.

Your question makes me suddenly understand DaveW's previous question/comment about aero load being larger than fuel load. The Nivomat does not need to differentiate between aero load and fuel load.

Here are examples of the aero vs fuel load issue that use made-up numbers and lots of simplifying assumptions.

If there is no heave spring at each end of the car-

With heavy fuel the ride height will be 10-35 mm, and with light fuel the ride height will be 15-40 mm. The 25 mm range for each fuel load is due to the difference in aero load from the slowest to fastest part of the track. It's true that the variation due to aero load (25 mm) is larger than the variation due to fuel load (5 mm). However, you will still have more downforce and speed with the 10-35 mm range as opposed to the 15-40 mm range. The Nivomat-type damper at each corner will not reduce the size of your 25 mm aero range, but it will keep this aero range centered at 10-35 mm instead of letting it drift up to the 15-40 mm range as fuel load burns off.

If there is a third/heave spring at each end of the car-

The car will consistently settle on the stiff heave spring on the straights regardless of fuel load, and the ride height there is maybe 5 mm. In corners the heavy fuel load will have a ride height of 10-20 mm and the light fuel load will have a ride height of 15-25 mm. The 10 mm range in corners for each fuel load is due to variation in aero load from the slowest corner to the fastest corner. Adding a Nivomat thingie at each corner will not change your heave spring, so the ride height along the straights is still ~5 mm for both fuel loads. However, now the Nivomat keeps the cornering ride height at the lower/better 10-20 mm range regardless of fuel load. It this example is worded poorly then just look at the no-heave-spring example.

[DaveW]

... However, keeping the range of dynamic suspension position tight at each corner requires spring and shock rates that are not optimum for mechanical grip. Compromises have to be made. You mentioned digressive rebound and chassis compliance. These are ways of improving mechanical grip within the context of tight ride height control.

Am I understanding this correctly?

Your interpretation of my stumbling attempt to explain the concept is correct. Thank you.

I introduced NASCAR simply as one example of race series for which the regulators attempt to limit performance with a minimum ride height rule (which translates to a minimum static ride height, because the regulators don't monitor ride height on-track). The rule is a nonsense because, as I tried to show, it is relatively simple to devise suspension set-ups that pull the vehicle down to the required ride height dynamically. As you suggested, the principal effect of the rule is that the resulting suspension set-up is not as "optimal" as it might have been. Hence, arguably, the rule simply makes vehicles slightly more dangerous than they might have been.

Back to the topic under discussion. I think your "Nivomat" solution to compensate for varying fuel weight would introduce a couple of problems. Its weight would, in most cases, increase the vertical height of the centre of gravity, and it would be difficult to control its tendency to "hunt" by changing pressure whenever the mean load supported by the suspension changed. My comment about the ratio of fuel load compared with aero load is relevant here, I think, because you would be requiring the system to operate accurately with a signal/noise ratio of around 0.1. I could imagine it actually increasing the mean ride height through corners following long straights, for example. I can't think that would be an easy problem to solve.

[ubrben]

So to be 100% clear Dave, you believe that the Red Bull is just using some combination of springs and dampers to jack the car down onto bump stops to get a low ride height regardless of fuel load?

Ben

[DaveW]

So to be 100% clear Dave, you believe that the Red Bull is just using some combination of springs and dampers to jack the car down onto bump stops to get a low ride height regardless of fuel load?

Ben

Truthfully, Ben, I can't answer your question with any authority. I have simply tried to point out that a reasonably well proven solution to the problem does exist & is certainly used elsewhere. I also took the opportunity to make a small protest against a particularly idiotic regulation that appears to be spreading across motor racing, including the lower reaches of GT.