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What kind of time is active suspension worth ?


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#1 pbukovca

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Posted 10 February 2012 - 14:49

I have an old issue of Race Car Engineering magazine from 1994 in which Neil Oatley said he only expected the the 94 spec F1 cars to lose only half a second per lap due to banning of active suspension. But in some F1 documentary video Frank Dernie claimed that active suspension
was worth seconds a lap. But in a video on youtube for the 1994 Monaco Grand Prix Murry Walker says that Schumacher in his Bennetton shattered the lap record there even though he did not have active suspension.

So I mean I'm a little confused. What kind of lap time benefit is active suspension actually worth? I'm also assuming that back then the systems were relatively crude compared to the computers and control algorthims that they could use today if it were unbanned.

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#2 cheapracer

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Posted 10 February 2012 - 15:29

Here's what I would do;

Find car's of similar/same engines running in the same year, one with active and one without active taking into consideration the average time difference between the 2 cars over the years, then the lap time comparison of the same team cars in later the races of 1993 and 1994.

Google is your friend.

#3 Ross Stonefeld

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Posted 10 February 2012 - 15:36

But the cars are going to be faster year on year. So maybe the half second loss includes the gain the 94 McLaren would have in laptime over the 93. And there might be softer tire compounds too. So both Oatley and Dernie's statements can be correct. Oatley in relative comparison, Dernie in absolute.

#4 cheapracer

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Posted 10 February 2012 - 16:11

But the cars are going to be faster year on year. .


Which will be averaged across the field.



#5 DaveW

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Posted 10 February 2012 - 21:01

What kind of lap time benefit is active suspension actually worth?

I don't think there is a definitive answer to your question.

I'm not familiar with the McLaren active system, but the Williams system was hydro-pneumatic, essentially to control ride height with a fairly primitive spring & damping strategy. So far as I'm aware, the Lotus system was the only one that attempted control ride height & optimise dynamic load variations. So, probably, a range of systems were developed by different teams all with there own different strengths & weaknesses.

In 1983 Lotus arrived at the Longbeach grand prix armed with a passive Renault engined car, and Active & Passive suspended DFV engined cars (the mix was because Renault refused to allow an hydraulic pump to be attached to their engine). De Angelis drove the Renault car, Mansell drove the active DFV car. De Angelis was quicker by a margin during practice (courtesy, no doubt, of a weight & serious power advantage). At one point, the active car had a problem that took time to fix, so Mansell drove the passive DFV car, & lapped (I recall), some 3 seconds slower than he had in the active car (it's fair to say that no serious time had been spent optimising the passive set-up).

In 1987 the Lotus 99T ran active suspension all year. At Monaco & Detroit Senna was the comfortable winner of both races. He also should also have won at Monza. During the course of the season the car became increasingly less competitive, largely because (I believe) the tyres became more conservative, which favoured passively suspended cars (the active car roughly halved the dynamic loads of a passive car, & essentially no longer worked the tyres hard enough - the clue was that Senna took twelve laps to reach racing speeds after a cold restart at Mexico).

It is a fairly obvious fact that "proper" (forgive me) active suspension is likely to be superior on "mechanical" (street) circuits, self-levelling suspensions are likely to be competitive on more conventional circuits, whilst passive suspension is likely to be competitive only on very smooth circuits. Tyres play a big part in this, of course, & an active suspension (properly set-up) is more likely to "look after" the tyres better & would be expected to "race" better than it "qualified".

For the above reasons, I would be happy to accept both of your quotes (under different circumstances).

Edited by DaveW, 10 February 2012 - 23:17.


#6 bigleagueslider

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Posted 10 February 2012 - 23:28

Don't know how much time an active suspension was good for in F1. But I recall seeing the TV race feed from a camera mounted on Mansell's FW15 chassis looking forward at the front wing and tire. It was absolutely mesmerizing to watch the suspension move up and down as the car drove around the track, while the distance between the front wing end plate and the track surface never varied by even a millimeter. It was incredible.

#7 desmo

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Posted 10 February 2012 - 23:48

Nowadays the FW and the ground maintain a similar spatial relationship, but the front suspension no longer moves up and down.

#8 DaveW

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Posted 11 February 2012 - 08:21

Nowadays the FW and the ground maintain a similar spatial relationship, but the front suspension no longer moves up and down.

Front ride height was sheduled to increase with airspeed (to account for tyre deflection) and, amongst other minor adjustments (roll with lateral etc.), to decrease with abs(steer angle) to increase available grip....and the suspension responded to road inputs like a proverbial Formula Ford. It also ran a displacement limiting algorithm, eerily similar to the one patented by the Lord Corp - but thats life, I guess (by the way, I still have a copy of the code to prove prior art).

Edited by DaveW, 11 February 2012 - 09:06.