F1 2010: Ride height adjustments during pit stops

[autogyro]

You applied it to tyre dynamics not suspension roll and pitch.
To be fair it is directly connected to ride height control.

[ReubenG]

@ Ringo:

I would be quite concerned about the natural frequency of the tank sitting on a spring. My first guess would be that the spring would have to be relatively soft - if not, the spring carries most of the fuel weight and the hydraulic link to the damper would not carry much load (which then defeats its purpose).

So one has a significant mass sitting on a spring of low stiffness = low natural frequency. I don't know the pitch / roll / bounce frequencies of an F1 car but if these are of comparable magnitude to the frequency of the tank/spring/hydraulic link system then you run the risk of exciting a resonance in the tank.

[DaveKillens]

I like Ringo's concept, it is very intelligent and well-thought out. My only concern is that this system may be interpreted as part of the suspension system, and the fact it alters the suspension. I recell the noise about Renault's mass damper, and how it too fell afoul of the regulations.

A few years ago, one of the Space Shuttles sitting on the pad awaiting launch developed a problem on a hydraulic actuator in the tail. problem was, to properly replace this unit, and bleed out any air it had to be trundled back to the servicing building, detached from the external tank and solid rocket boosters and laid horizontal. Obviously, a loss of at least two weeks. Instead the bright engineers froze all the hyrdaulic lines accessing the actuatur, removed and replaced same, and avoided the massive headache of bleeding air out this hydraulic system.

The problem with the type of suspension requirements is that the car has to sit low on qualifying, yet have enough clearance once all that fuel was added. So the problem is to use something posessing stored energy to lift the car back up, after Q3. I was thinking of some hydraulic system that had an air/oil separator, some bladder, stored under high pressure, yet frozen before qualifying so that the stored high pressure hydraulic fluid could not exit the little frozen canister.

A coupld of hours after qualifying is over and the cars are in parc fermee, the hydraulic fluid thaws, and since it's under pressure, extend a small jack to push the suspension back to maximum height.

[ringo]

@ Ringo:

I would be quite concerned about the natural frequency of the tank sitting on a spring. My first guess would be that the spring would have to be relatively soft - if not, the spring carries most of the fuel weight and the hydraulic link to the damper would not carry much load (which then defeats its purpose).

So one has a significant mass sitting on a spring of low stiffness = low natural frequency. I don't know the pitch / roll / bounce frequencies of an F1 car but if these are of comparable magnitude to the frequency of the tank/spring/hydraulic link system then you run the risk of exciting a resonance in the tank.

Yeah the excitation of the tank, fuel, by the spring and car is a concern. It would lead to more complication in the form of damping the tank, which would have an increasing natural frequency as the fuel is used up. Though it's possible the tank and fuel could be self damping, and maybe out of the range of operating frequency of the car's motion.
I think if it is interpreted as part of the suspension, it may be a bit confusing that the suspension is fueling the car. Then it's possible the tank wont be considered as part of it, but the piston it's sitting on could be.

The freezing thing is a good idea as well. It's very direct.

[segedunum]

My only concern is that this system may be interpreted as part of the suspension system, and the fact it alters the suspension. I recell the noise about Renault's mass damper, and how it too fell afoul of the regulations.

Well you would hope that it would be interpreted as part of the suspension system. Renault's mass damper ultimately had a target painted on it because it wasn't part of the suspension system. The McLaren pioneered J-damper, of which there will be many variations on other cars and does effectively the same thing as the mass damper did, is considered a part of the suspension and so has been passed legal for many years.

[DaveW]

Well you would hope that it would be interpreted as part of the suspension system. Renault's mass damper ultimately had a target painted on it because it wasn't part of the suspension system. The McLaren pioneered J-damper, of which there will be many variations on other cars and does effectively the same thing as the mass damper did, is considered a part of the suspension and so has been passed legal for many years.

Apologies, segedunum, but Renault's "mass damper" & the McLaren "J-damper" are fundamentally different devices.

The "mass damper" (aka "dynamic absorber") controlled the sprung mass response to road & driver disturbances. Its effectiveness is directly related to (front) spring stiffness, & it would be most efficient with the springs replaced by rigid links. It is a lightly damped "resonant" device, with a natural frequency that must be "tuned" accurately to the vehicle. Whether it is considered to be part of the suspension or not depends on the definition of "suspension". It certainly can help to isolate the sprung mass from road inputs & to play its part in dissipating disturbance energy. I suspect any good textbook on mechanical vibration will set out the theory.

The "J-damper", or "inerter", as used in race cars is a device that connects in parallel with a normal spring & damper. Hence (& contrasting with the mass damper) it will not work if it is "locked out" by an ultra-stiff spring. Its function is to store, rather than to dissipate, disturbance energy so that the associated damper can deal with it more effectively. The inerter was "discovered" - more accurately re-discovered - by Malcolm Smith of Cambridge University. Google "inerter" to learn more.

[segedunum]

Apologies, segedunum, but Renault's "mass damper" & the McLaren "J-damper" are fundamentally different devices.

They're not. Both devices are designed to take (deflection) energy away from the sprung chassis that would otherwise destabilise it, and either absorb or store it in an unsprung part of the chassis to increase stability. That's the basic concept in a nutshell. F1Technical even has its own pretty good commentary on what both systems do:

http://www.f1technical.net/features/10586

The particulars of how both systems do that isn't important here. The comparison being made was that the proposed system, if indeed Red Bull even have it, would be compared to the TMD system Renault had. TMD was ultimately frowned upon because it wasn't part of the suspension system. Given what we've seen of how a Red Bull system might work given existing concepts then it is highly likely to be an integral part of the suspension system in the way that inerters have been for a while, which is why I made that comparison. Certainly, Red Bull would be a little silly to design it any other way.

[autogyro]

I cannot see how a comparison can be made between a mass damper and a ride levelling suspension system.

[segedunum]

Neither do I, considering it would be a suspension system in itself.

[DaveW]

They're not. Both devices are designed to take (deflection) energy away from the sprung chassis that would otherwise destabilise it, and either absorb or store it in an unsprung part of the chassis to increase stability. That's the basic concept in a nutshell.

Mmm. I think you might be confusing function with implementation. Would your answer have been similar if I had, for example, contended that a nuclear power station & a wind farm were fundamentally different, even though both are intended to generate electrical power?

However, as autogyro has suggested, perhaps this is not the place to continue the debate.

[OO7]

Hello

I've been wondering, rather than allowing the fuel cell to be placed on a dynamic mount, couldn't a baffle within the fuel be used to adjust the ride height in a similar fashion. Rather than worrying about the cg shift of a large amount of fuel, in this case you'll only be concerned with the baffle?

[autogyro]

Hello

I've been wondering, rather than allowing the fuel cell to be placed on a dynamic mount, couldn't a baffle within the fuel be used to adjust the ride height in a similar fashion. Rather than worrying about the cg shift of a large amount of fuel, in this case you'll only be concerned with the baffle?

It could be but it would be defined as 'active' suspension.

[segedunum]

However, as autogyro has suggested, perhaps this is not the place to continue the debate.

Probably not. Whatever this system is I doubt it has much to do with any kind of existing damping system.

[OO7]

Hello

I've been wondering, rather than allowing the fuel cell to be placed on a dynamic mount, couldn't a baffle within the fuel be used to adjust the ride height in a similar fashion. Rather than worrying about the cg shift of a large amount of fuel, in this case you'll only be concerned with the baffle?

It could be but it would be defined as 'active' suspension.

Wouldn't the moveable fuel cell also be defined as being part of an active suspension?

[ringo]

Hello

I've been wondering, rather than allowing the fuel cell to be placed on a dynamic mount, couldn't a baffle within the fuel be used to adjust the ride height in a similar fashion. Rather than worrying about the cg shift of a large amount of fuel, in this case you'll only be concerned with the baffle?

A fuel tank is part of the sprung mass and it would be supported by the suspension. nothing active about that.

A baffle would be a breach of the fuel cell construction regs. It would be a safety issue if suspension control has to pass through the cell wall.


COG shift is not a problem, in fact it could be good because it correlates to the motion of the vehicle and could act like an anti sway bar of sorts.
If fuel weight shifts to one side, suspension on that side will raise a little. On the opposite lighter side the suspension would lower a little, so the car will be flatter in the turns.
This is what i think, or i could be looking at it too simply.