Hydraulic Suspension tricks

[CBeck113]

I personally would place the suspension elements near the waste gate exhaust.
Then I can influence the temperature any time I like within a short time due to the high difference between the hydraulics and the exhaust.

Actually you can't, otherwise it would be active. Currently it is passive because it cannot be controlled by the driver or team, but through the air flow (=speed of car, although vortices could be used to direct the air flow at varying speeds) and temperature. It's a fluid in a closed system: T up, P up, suspension changes (probably up, but if they are allowed to use a fulcrum, who knows...).

[matt21]

I do not see the need for such a system. All the metrics mentioned are free to be set before the car is on the track. Are there any rules the restrict the areas of adjustment mentioned in the article if made in the paddock?

The parc ferme rules come in to play when the car is leaving the pit lane for the first time in Q1 and end after the race is started.
You are not allowed to change anything on the suspension in this time.
Nevertheless you can drain/replenish fluids with a gravity of less the 1.1.

Actually you can't, otherwise it would be active. Currently it is passive because it cannot be controlled by the driver or team, but through the air flow (=speed of car, although vortices could be used to direct the air flow at varying speeds) and temperature. It's a fluid in a closed system: T up, P up, suspension changes (probably up, but if they are allowed to use a fulcrum, who knows...).

Technically I´m controlling the temperature in the exhaust. As a side effect the nearby placed hydraulic elements are heated as well.

One thing I don´t know from the top of my head is, if you are restricted in the input signals you are using for the ECU of the engine/wastegate.

[Big Mangalhit]

The FIA even came out and said that teams could use exhausts as a form of heating if they wanted. What Mercedes is doing is just a clever interpretation of the rules, but is perfectly legal and I can't see them adding rules in to stop it. If you leave it open to air it could be deemed as offering a cooling effect on the oil if that was required for some reason.

Teams will just converge on this idea and that will be the end of it.

But if you are exchanging heat from oil/exhaust to the suspension's hydraulics you are in fact using active suspension so it is illegal even if you claim your primary intent is cooling of oil/exhaust. Like using a fan car is considered moveable aero even if you claim the fans are there to cool the engine/radiators whatever.

[Phil]

I think the exploit is very simple, legally speaking. Hydraulics uses oil. Oil pressure is dependant on temperature. Clever placement of actuators influences the temperature and therefore the suspension.

Legally and technically speaking, its not much different than the flexy wing debate. All materials flex. Its a question of force. If there are no rules that state how much flex is allowed at x force, one can not punish for flex.

The hydraulic is similar as in that the system itself has a logical predictable influence. In that sense, it is different than an "active fan" that is clearly an activate component that is out of the chain. However if the fan was powered by the drivetrain, it could be deemed "passiv" IMO.

On some level, Mercedes feels (according to the above article) that their interconnected suspension is legal too. Yet because the system is so complicated, there is a large area of interpretation. The risk is if they use it, it could go either way since the legality of their system evolves around arguing the legality of it in front of the stewards post race. Doing so could risk a disqualification, hence why they are not using it.

As the article suggests - Force India is on shaky grounds as their system relies on people actively filling up the system with pre heated oil. Mercedes system is indeed quite clever.

[Big Mangalhit]

Well powering a fan with the drivetrain would still make it moveable aero, doesn't matter where the energy comes from, even if there is no input to start it or control it.

What is the teams had two redundant oil lines where they could choose which is used at each time. One would pass near the suspension hydraulics and the other far away. They could in theory control (probably not fine tune but still some tune) the characteristics of the suspension on the fly, maybe adjust/correct the ride high according to the weight of the gas tank?

[Big Mangalhit]

Well powering a fan with the drivetrain would still make it moveable aero, doesn't matter where the energy comes from, even if there is no input to start it or control it.

What if the teams had two redundant oil lines where they could choose which is used at each time. One would pass near the suspension hydraulics and the other far away. They could in theory control (probably not fine tune but still some tune) the characteristics of the suspension on the fly, maybe adjust/correct the ride high according to the weight of the gas tank?

[PhillipM]

But if you are exchanging heat from oil/exhaust to the suspension's hydraulics you are in fact using active suspension so it is illegal even if you claim your primary intent is cooling of oil/exhaust. Like using a fan car is considered moveable aero even if you claim the fans are there to cool the engine/radiators whatever.

But a powered fan IS active aero, no matter which way you cut it. If you had a fan that was driven by the airflow around the car itself, that would be legal as it would be passive - but it would fall foul of the moveable aerodynamics rule instead.
Merely exchanging heat from the oil/exhaust to the suspension hydraulics is only active if it's monitored and controlled, so you're picking up from a feedback loop, it doesn't need to be like that, it could be purely passive heat transfer one way.
However, saying that, I'm not sure you could control ride height well enough passively for it to be worth bothering anyway, this may all just be smoke and mirrors - otherwise you'd be wanting a slow rise in pressure/temperature over the course of the race to compensate for fuel loss, or vice versa and use hot oil that slowly cooled, depending on which side of the system you're using.
Whilst that might be feasible with the hot oil cooling scenario, I'm not so sure about vice versa as people are making out for mercedes - that would have to be a very carefully insulated and controlled environement at the slow heating rates required, you'd have evidence of heatshielding/insulation around the gearbox bellhousing where the actuators are.

[basti313]

The FIA even came out and said that teams could use exhausts as a form of heating if they wanted. What Mercedes is doing is just a clever interpretation of the rules, but is perfectly legal and I can't see them adding rules in to stop it. If you leave it open to air it could be deemed as offering a cooling effect on the oil if that was required for some reason.

Teams will just converge on this idea and that will be the end of it.

But if you are exchanging heat from oil/exhaust to the suspension's hydraulics you are in fact using active suspension so it is illegal even if you claim your primary intent is cooling of oil/exhaust. Like using a fan car is considered moveable aero even if you claim the fans are there to cool the engine/radiators whatever.

I think it is difficult to claim it is movable aero or active suspension. Once you drive the car the temperatures should be more or less equal between Q and Race. And active valves are not allowed.
If I understand it correctly, they simply control the ride height of the rear axle. When the car is cold it is low, when the car is hot, it is high. This directly lowers the height of the front wing, which is limited to a minimum by the rules.
So I do not think it is in conflict with complicated rules, it is a simple cheat on bodywork dimensions (minimum height).

[Phil]

Well powering a fan with the drivetrain would still make it moveable aero, doesn't matter where the energy comes from, even if there is no input to start it or control it.

Moveable aero is a different rule. I was merely arguing active/passive.

As for the Mercedes system. I am actually quite sure the system is "active" in a way for it to be effective. Maybe they can control how much heat goes through that system. But i presume its so complicated and hidden away that scrutineering would be quite difficult. Imagine, the Fia would need sensors to determine the oil pressure throughout the race to see any difference. And if they do determine flactuation in the pressure, they would have to prove or make a point what and how it is being influenced, other than by "natural lucky coincidence".

Better to just ban hydraulic suspensions under the ground that you cant police it. Or live with it and deem it legal. But that would be a question of how performance effective it is and what the cost is and if the FIA want to promote and encourage more development in this area or block it entirely.

[CBeck113]

Actually you can't, otherwise it would be active. Currently it is passive because it cannot be controlled by the driver or team, but through the air flow (=speed of car, although vortices could be used to direct the air flow at varying speeds) and temperature. It's a fluid in a closed system: T up, P up, suspension changes (probably up, but if they are allowed to use a fulcrum, who knows...).

Technically I´m controlling the temperature in the exhaust. As a side effect the nearby placed hydraulic elements are heated as well.

One thing I don´t know from the top of my head is, if you are restricted in the input signals you are using for the ECU of the engine/wastegate.

We agree, I was just focused on the control of the temperature, you the source of the additional energy. My point was, no matter the source, it can't be actively regulated, so as the heat source gets warmer, so will the element, which will continuously increase the pressure - the question being if that is desirable, hence my comment. Aiming an internal vortex at this element at certain speeds could help control the temperature, but that must be adjusted from track to track, like the FRIC systems. You cannot use the input signals to adjust any suspension components, that would be active...

[hardingfv32]

ASSUME that the suspension oil is being heated AND that it is legal!

How can it be used to change the suspension settings?

1) I do not see how it can change the spring rate.

2) You could change the shock valving/characteristics making the shocks softer (lower viscosity?).

3) As a ride height adjustment for Qualifying. Run lower during qualifying (high floor wear rate) and then raise the chassis during the early laps of the race to a low floor wear rate.

Brian

[matt21]

ASSUME that the suspension oil is being heated AND that it is legal!

How can it be used to change the suspension settings?

1) I do not see how it can change the spring rate.

2) You could change the shock valving/characteristics making the shocks softer (lower viscosity?).

3) As a ride height adjustment for Qualifying. Run lower during qualifying (high floor wear rate) and then raise the chassis during the early laps of the race to a low floor wear rate.

Brian

Regarding your questions:

1) Change of stiffness according to fuel load would be good. Could be achieved with a gas reservoir as in an airspring.

2) heat is changing viscosity -> change of damper characteristics

3) more heat -> more oil volume -> height increases

[Greg Locock]

I may have missed a bit but mechanical engineering has a long history of using hot sources to power stuff. It would take minutes to rough out a black box that used oil as the hot side and air as the cold side, with an output of force, torque, or current.

[hardingfv32]

I guess I should state the ASSUMPTION that the heat source has a near constant temperature (exhaust for example).

If this is the case we are talking about a system that changes after the start of a session. Cold in the paddock (maybe after being cooled) and hot while on track. So you start the session with one setup and after a few laps you have a changed setup that is maintained for the balance of the session.

This being the case:

1) Why would you want to change spring rates instead of ride height for fuel load management?

2) Why change damper characteristics?

Brian

[matt21]

I guess I should state the ASSUMPTION that the heat source has a near constant temperature (exhaust for example).

If this is the case we are talking about a system that changes after the start of a session. Cold in the paddock (maybe after being cooled) and hot while on track. So you start the session with one setup and after a few laps you have a changed setup that is maintained for the balance of the session.

This being the case:

1) Why would you want to change spring rates instead of ride height for fuel load management?

2) Why change damper characteristics?

Brian

Regarding your questions:

1) What you really want is a specific chassis frequency and constant ride height. This is depending on the weight. The more weight you have the harder the spring for the same frequency. So in order to maintain a constant frequency/ ride height it would be favourable to soften the spring during the race.

2) If you change the springe rate you have to adapt the damper characteristics. Otherwise you would change the behavior of the car.