Moose test anyone

[saaby93]

Showing tests with no Activa listed aren't exactly evidence

[anonymous-user]

BlueMR2 said:

Max_Torque said:

BlueMR2 said:

Max_Torque said:

er, it's a "lets just make up a complete load of random numbers" test then.... A Kia C'eed is the same as the Exige???

And as for the Activa, "active" suspension isn't actually any "better" than non active suspension. The cars lateral weight transfer (and hence ability to keep all 4 tyres evenly loaded on the slip vs lateral g curve) is set purely by it's track, mass, and C of G height (for static case) So no matter how "stiff" the suspension on an Activa is, it's not much help really, when compared to the Exige???

If the test is effectively a "slalom" test, and the "passing" criteria is max speed without spinning, then cars with stability control (and the massive yaw authority that gives) will easily "outperform" even a pretty sporting car without. That may explain some of the results??

You've never driven a car with active suspension before have you.

You don't understand the concept of weight transfer do you??? So by simply adding active suspension F1 designers wouldn't need to bother with all that conventional low C of G, wide track stuff, in fact, they could just stick active suspension on a london bus perhaps?????


So, being less antagonistic:

Lets take 2 identical vehicles, (say 2 citroen xianta's) and fit one with active suspension(A), and one with passive suspension(B):

Car A & Car B, have identical spring rates, identical geometery (camber,toe, castor etc), identical mass, ride heights, and tyres. But Car A has the ability to counter the rolling moment by applying an "active" opposite function to it's antiroll bars to reduce the total level of sprung body roll.

So if, we assume that for the first test, the spring rates of both cars are what would be considered a typical road car setting (~1Hz ride rate for example). In this case, the lateral weight transfer for any given cornering load will be the same for both vehicles (as mass CofG height & track are equal), the difference being that the "active car" will have less body angle. This could give a lateral g increase if it keeps the tyre at a more advantageous attitude to the road (primarily camber control). For both cars, the weight removed from the inside tyres and added to the outside tyres is the same, it's just the active car has not rolled as much to transfer than mass (effectively it has a stiffer roll couple)

Now, lets repeat the test, leaving Car A as it was previously, but lets try 2 things with car B, firstly(1), lets stick on much more negative camber to the wheels, then(2) lets stick on really stiff antiroll bars.

Now again both cars corner at the same lateral g, so both have the same lateral mass transfer. but this time, our "passive car" even though for our 1st case it rolls more, it now presents the tyre to the road at the optimum angle so can match the active car. or secondly (2 with stiff suspension) it rolls the same as the active car, so matches it here too.


In summary, the ADVANTAGE of active suspension (especially when talking about a slow "reactive" system* such as the Activa's) is the ability to allow a car to have both a decent ride quality AND a high lateral G ability. It cannot increase the lateral g ability beyond that set by the basic physical layout of the car, nor could it improve the ride quality beyond that possible by conventional suspension, but it does mean you can "optimise" you car to have the best of both worlds.

If you compare an Activa aginst say a 911 gt3RS, you will find that even in the "stiffest" mode the active still feel like a boat on a track compared to the low, wide, lightweight porka...... However, on the way home from the test, the Activa will have a mch nicer ride ;-)

• The latest ARC systems in development are just starting to move from a totally reactive systems, i.e. measure body roll, adjust antiroll to compensate. to adaptive and properly active, i.e. using wheel g information, steering rate, yaw rate, etc to "pre-adjust" the system. The Holygrail is to have a car that can read the map the road BEFORE it's wheels get there, and be ready to perhaps even move them out of the way of bumps etc (although, this will only help the ridequality / traction on bumpy roads, and again still can't change the static smooth road capabilities)

If you want some "homework" go find a graph of tyre slip vs friction coefficient and understand why "equally" loading 4 tyres on a car is the most optimum for maximising that vehicles dynamic capability (hint, it's a very non-linear shaped graph!!)

(and btw, i was part of the team that developed/calibrated the ARC for JLR, so go drive a RRS and get back to me on how you managed to out corner a lambo with it ;-)

I cant comment on the Citroen setup as i know nothing about it, however i will talk about the car i owned previously.

Your example uses two passive cars with identical spring rates one having some odd anti roll bar that can change its stiffness. This makes me think you still don't understand for a few reasons.

1. A fully active car has no anti roll bars, it doesn't need them, so you can't change them during the drive as there are none to change.

2. Spring rate, sorry but fully active doesn't have any springs either.

You later talk about moving to fully active systems, the ones like i'm talking about, which is why i call it active suspension, like Toyota were producing on their cars 20 years ago.

http://planetsoarer.com/UZZ32/uzz32.html < shows you details from Toyotas work and reasons for using it.



http://www.youtube.com/watch?v=IHK_2eoBaFU < this is a video of an active soarer followed by a standard coil suspension soarer.

http://www.youtube.com/watch?v=S2QV_PaUWhs < this one shows he range of motion available doing the diagnostic "dance"

This image shows an active suspension soarer at the same corner as a tems airbag suspension soarer


This shows the angle of a racing 944 against an active soarer


http://planetsoarer.com/UZZ30/UZZ30.htm < this link is a review of a normal coil suspension owners drive of an active suspension model.

I'll pass on driving a RRS unless you want to give it a proper active suspension system thanks. I doubr a bit of extra rollbar stiffness will make it that nice to drive. Maybe 4 wheel steer would help it .

Couple of points:

"the Spring rate" of a suspension system does not have to be provided by "springs" assuming you mean a "torsionally stressed helically wound wires". Every car has a spring rate, even active hydropneumatic ones!

The Citroen Activa that this thread is about DOES have antiroll bars

20 years ago, you could not buy enough processing power to even calculate the required control parameters in real time for true "adaptive active suspension"...... The RRS system is massively powerful by comparison.

It doesnt matter where the "opposing roll moment" comes from ("arb's" or "springs" the effect is exactly the same. (arb's are just springs with a parametricaly opposite reaction point)


Posting a picture of some random car, (race or otherwise) to "Prove" that active suspension is much better than passive suspension is pointless. i could just post a pic of say an F2 car, with passive suspension and wheel rates of >5Hz, a CogG hgt about 4" off the road, weighing <500kg, and guess what, it wouldn't show any roll at all even pulling 3.5g in a bend!!!!

In fact, i shall: wow , look at that, no roll at all, wow, passive systems kick ass!!!




A std Soarer is a blamange (compared to say a GT3 RS), so i'm not suprised that an "active soarer" is a lot better in terms of chassis dynamics

To reiterate: Active Suspension (in the activa's case, Active Roll Control) enables the manufacturer to produce a car that can furfill a great spread of dynamics than a purely passive one. By this i mean the active car can have a lower spring rate and greater roll for a smoother ride quality, AND a stiff low roll setup for maximum cornering ability.
BUT, The active car will corner NO "better" than one with a passive setup with the same rates as the active car when in "stiff mode".

[Kidders]

You can tell you've never driven one.

[Fox-]

Max_Torque said:

You don't understand the concept of weight transfer do you??? So by simply adding active suspension F1 designers wouldn't need to bother with all that conventional low C of G, wide track stuff

You do realise Active Suspension was BANNED from F1 simply because it was 'too good', right?

The reason F1 cars dont have it is not because it wouldnt make them better, its because the FIA banned it.

Surely you knew that?

[anonymous-user]

Ok i give up, you lot are right. there is only so many times i can try to explain the true physics behind lateral weight transfer.


An F1 car with Active suspension can not corner harder than one with passive suspension for any given corner!! The reason Active suspension in F1 was an advantage was that it allowed the underfloor aerodynamics to be controlled during events like running over kerbs or under max braking. (the small gap under an F1 car at the time (no "planks" under the car back then) meant the the cars ran "in ground effect" so were very sensitive to the distance and attitude to the ground). On an F1 car the maximum aero downforce can be as much as 3x the mass of the car, so a conventional passive suspension system cannot maintain a fixed "ride height" during all modes of aero loading.

A Citroen Activa or a Lexus Soarer however do not quite produce the same downforce or rely on ground effect to the same degree............ ;-)

[davepoth]

Max_Torque said:

Ok i give up, you lot are right. there is only so many times i can try to explain the true physics behind lateral weight transfer.


An F1 car with Active suspension can not corner harder than one with passive suspension for any given corner!! The reason Active suspension in F1 was an advantage was that it allowed the underfloor aerodynamics to be controlled during events like running over kerbs or under max braking. (the small gap under an F1 car at the time (no "planks" under the car back then) meant the the cars ran "in ground effect" so were very sensitive to the distance and attitude to the ground). On an F1 car the maximum aero downforce can be as much as 3x the mass of the car, so a conventional passive suspension system cannot maintain a fixed "ride height" during all modes of aero loading.

A Citroen Activa or a Lexus Soarer however do not quite produce the same downforce or rely on ground effect to the same degree............ ;-)

Wrong. Read up about Lotus' system again. It didn't work properly because it reduced the slip angle on the tyre too much. It made the car so grippy in corners that the tyres didn't warm up properly for braking! What you are talking about is active ride height control, which is a different thing again.

As I said before, the active suspension works by making sure that the car keeps the optimum contact patch on the road at all times. So actually yes, the Activa probably does have more rubber on the road in a corner than a Viper. Think about what happens to the wheel when the suspension is compressed - on every car I can think of with passive suspension the camber changes on the wheel. The wheel has a flat contact patch, so that means that less than the whole width of the contact patch will be on the road when the suspension is loaded up.

Edited by davepoth on Sunday 31st October 16:05

[anonymous-user]

davepoth said:

Max_Torque said:

Ok i give up, you lot are right. there is only so many times i can try to explain the true physics behind lateral weight transfer.


An F1 car with Active suspension can not corner harder than one with passive suspension for any given corner!! The reason Active suspension in F1 was an advantage was that it allowed the underfloor aerodynamics to be controlled during events like running over kerbs or under max braking. (the small gap under an F1 car at the time (no "planks" under the car back then) meant the the cars ran "in ground effect" so were very sensitive to the distance and attitude to the ground). On an F1 car the maximum aero downforce can be as much as 3x the mass of the car, so a conventional passive suspension system cannot maintain a fixed "ride height" during all modes of aero loading.

A Citroen Activa or a Lexus Soarer however do not quite produce the same downforce or rely on ground effect to the same degree............ ;-)

Wrong. Read up about Lotus' system again. It didn't work properly because it reduced the slip angle on the tyre too much. It made the car so grippy in corners that the tyres didn't warm up properly for braking! What you are talking about is active ride height control, which is a different thing again. As I said before, the active suspension works by making sure that the car keeps the optimum contact patch on the road at all times. So actually yes, the Activa probably does have more rubber on the road in a corner than a Viper.

Edited by davepoth on Sunday 31st October 16:01

Edited by davepoth on Sunday 31st October 16:01

really! wow! you're the greatest, i bow in reverence to your truth!!!


(btw this:
It made the car so grippy in corners that the tyres didn't warm up properly for braking!

has to be the greatest "bad science" statement i have ever read....... ;-)

Edited by anonymous-user on Sunday 31st October 16:07

[davepoth]

Max_Torque said:

has to be the greatest "bad science" statement i have every read....... ;-)

http://www.autozine.org/technical_school/suspensio...

"Worst of all, Team Lotus did not get specially developed tyres to extract its potential. As the active suspension reduced tyre's slip angle, the tyres generated insufficient heat to attain the necessary working temperature."

How do racing drivers get heat into their tyres when they are lapping behind the safety car? they weave from side to side because that's the best way of warming the tyres. Please think before typing.

Edited by davepoth on Sunday 31st October 16:10

[anonymous-user]

sorry, won;t happen again

[saaby93]

davepoth said:

How do racing drivers get heat into their tyres when they are lapping behind the safety car? they weave from side to side because that's the best way of warming the tyres.

I thought I'd read that was for such a short length of time it had minimal benefit.
It did make the drivers happier that they might be doing something useful though

[davepoth]

There is that. The point is though that the lateral loading and slip angle of the tyre as the car corners (albeit at much higher speeds than behind the safety car) is one of the main things that heats the tyre. And because of the massive increase in contact patch provided by the active suspension, while they had the grip around the corners, they didn't have it for when the whole contact point is used even on passively suspended cars - the braking zone.

[anonymous-user]

HAve you considered doing some F1 consulting DP?? They really could use a man of your skills i think??

[busta]

Max-Torque, your entire argument regards active suspension seems to be 'all other things being equal, any car can be set up to pull the same lateral G'.

This is of course true, but cars also have to do things like accelerate, brake and drive in straight lines over bumps. A car with masses of negative camber, high spring rates and stiff anti-roll won't be much good at any of these other things, which is why the Activa can punch so much higher than it's weight. The active suspension allows it to maintain optimum tyre contact whilst retaining a compliant ride and sensible wheel geometry.

[BlueMR2]

Max_Torque said:

BlueMR2 said:

I cant comment on the Citroen setup as i know nothing about it, however i will talk about the car i owned previously.

Your example uses two passive cars with identical spring rates one having some odd anti roll bar that can change its stiffness. This makes me think you still don't understand for a few reasons.

1. A fully active car has no anti roll bars, it doesn't need them, so you can't change them during the drive as there are none to change.

2. Spring rate, sorry but fully active doesn't have any springs either.

You later talk about moving to fully active systems, the ones like i'm talking about, which is why i call it active suspension, like Toyota were producing on their cars 20 years ago.

http://planetsoarer.com/UZZ32/uzz32.html < shows you details from Toyotas work and reasons for using it.



http://www.youtube.com/watch?v=IHK_2eoBaFU < this is a video of an active soarer followed by a standard coil suspension soarer.

http://www.youtube.com/watch?v=S2QV_PaUWhs < this one shows he range of motion available doing the diagnostic "dance"

This image shows an active suspension soarer at the same corner as a tems airbag suspension soarer


This shows the angle of a racing 944 against an active soarer


http://planetsoarer.com/UZZ30/UZZ30.htm < this link is a review of a normal coil suspension owners drive of an active suspension model.

I'll pass on driving a RRS unless you want to give it a proper active suspension system thanks. I doubt a bit of extra rollbar stiffness will make it that nice to drive. Maybe 4 wheel steer would help it .

Couple of points:

"the Spring rate" of a suspension system does not have to be provided by "springs" assuming you mean a "torsionally stressed helically wound wires". Every car has a spring rate, even active hydropneumatic ones!

The Citroen Activa that this thread is about DOES have antiroll bars

20 years ago, you could not buy enough processing power to even calculate the required control parameters in real time for true "adaptive active suspension"...... The RRS system is massively powerful by comparison.

It doesnt matter where the "opposing roll moment" comes from ("arb's" or "springs" the effect is exactly the same. (arb's are just springs with a parametricaly opposite reaction point)


Posting a picture of some random car, (race or otherwise) to "Prove" that active suspension is much better than passive suspension is pointless. It shows how little roll the car has compared to a car specifically adapted to do track work.

i could just post a pic of say an F2 car, with passive suspension and wheel rates of >5Hz, a CogG hgt about 4" off the road, weighing <500kg, and guess what, it wouldn't show any roll at all even pulling 3.5g in a bend!!!! i'd like to see that pass an mot then do a continental trip with 4 passengers and luggage with all feeling as fresh as when they set off.

In fact, i shall: wow , look at that, no roll at all, wow, passive systems kick ass!!!




A std Soarer is a blamange (compared to say a GT3 RS), so i'm not suprised that an "active soarer" is a lot better in terms of chassis dynamics

To reiterate: Active Suspension (in the activa's case, Active Roll Control) enables the manufacturer to produce a car that can furfill a great spread of dynamics than a purely passive one. By this i mean the active car can have a lower spring rate and greater roll for a smoother ride quality, AND a stiff low roll setup for maximum cornering ability.
BUT, The active car will corner NO "better" than one with a passive setup with the same rates as the active car when in "stiff mode".

You talk about stiff mode alot. The Soarer has one mode, the no roll mode. It doesn't roll, dive or squat, at any time.

If you look at my posts i have only talked about active suspension, the citroen seemingly doesn't have this advanced level of ability.

I'd like you to define what a car would have to do for you to regard it as true adaptive suspension.

above post said:

20 years ago, you could not buy enough processing power to even calculate the required control parameters in real time for true "adaptive active suspension"

The Toyota paper above says that the car can pull more g than a non active suspension car.

With regards spring rate how do you work that out with a fluid and nitrogen system?

If the car has no fluid or leaks fluid the suspension will drop down as low as it can before the struts bottom out, with no spring at all. Can you make a spring value of fluid? The suspensions height is controlled by the hydraulic pump which gives enough pressure to keep it at the standard or high height as chosen by a switch. The more the car resists leaning the more pressure will be needed to do so, the system allows fluid in or out to allow bumps to be absorbed using a large hydraulic pump run from the engine, using some power and increasing fuel consumption, another reason they are not that common. It would be hard to keep the emissions down and the car would need a powerful engine were it not to be shopping car slow.

What cars do you regard as having active suspension and what cars have you driven with active suspension?

[Beyond Rational]

Xantia Activa - Moose test video - 80 km/h though

http://www.youtube.com/watch?v=btjo5qqU62M&fea...

The mighty Xantias cornering prowess

http://www.youtube.com/watch?v=09-C33SrJi8

[Kidders]

I blame this thread, i am finalising a deal on a 1997 Activa. This one will see a few track days...

[Beyond Rational]

Kidders said:

I blame this thread, i am finalising a deal on a 1997 Activa. This one will see a few track days...

Brilliant If you strip them out, how easy is it to get them to sit right afterwards?

[saaby93]

http://www.youtube.com/watch?v=rJPr-gQR234
Stupid place to park the camera car - reminds of that Robert Mark NTNON sketch

[Kidders]

Beyond Rational said:

Kidders said:

I blame this thread, i am finalising a deal on a 1997 Activa. This one will see a few track days...

Brilliant If you strip them out, how easy is it to get them to sit right afterwards?

They are self levelling.

[saaby93]

On track
http://www.youtube.com/watch?v=Eu1H1G88hOc
afterwards
http://www.youtube.com/watch?v=EiPoQF6h_6g

Edited by saaby93 on Sunday 31st October 17:42