Lotus E21 Renault

A place to discuss the characteristics of the cars in Formula One, both current as well as historical. Laptimes, driver worshipping and team chatter does not belong here.
korzeniow
korzeniow
25
Joined: Wed Feb 03, 2010 2:51 am
Location: Cracow/Poland

Re: Lotus E21 Renault

Post

Blackout wrote:Another pic. still the same aero package. rake looks important though, and the splitter is almost touching the ground

Image
Yeah, just compate it to this:

Image

here's Mercedes rake:

Image

the rake seems to go down when drivers are accelerating, here's picture in and out of the corner:

Image
It's been a long time since we drove last time, but it has also been a short time at the same time
Roam Grosjean ponders the passing of time on the first day of testing at Jerez
February 5, 2013

shelly
shelly
144
Joined: Tue May 05, 2009 11:18 am

Re: Lotus E21 Renault

Post

teh intersting thing is that during the aero test they run active suspensions, which keep the car at the desired ride heights. Hence the pictures taken during aerotests should give a better indication of the rake that the car shoul have . the one that is targeted during the race when all the dynamics come into play and "disturb" that
twitter: @armchair_aero

Rikhart
Rikhart
13
Joined: Tue Feb 10, 2009 7:21 pm

Re: Lotus E21 Renault

Post

korzeniow those pictures are not representative to assess the levels of rake, because they are taken in a corner, and you can see lots of body roll by looking at the front wing...

Huntresa
Huntresa
54
Joined: Sat Dec 03, 2011 10:33 am

Re: Lotus E21 Renault

Post

Also Lotus would be lower in the back if they have the FRIS system talked about since it lowers the back under certain pressure.

User avatar
ringo
231
Joined: Sun Mar 29, 2009 9:57 am

Re: Lotus E21 Renault

Post

Crucial_Xtreme wrote: Lotus ran hydraulically linked suspension before Mercedes. But unlike the Mercedes FRIC system, the Lotus design has used conventional springs and anti-roll bars to achieve most of the suspension effect, meaning the hydraulic link was only to supplement the spring when the car is heaving up and down.
Hmm, change of tune.. FRIC went from no springs, all hydraulic and air, to everything mechanical.
The hydraulic over mechanical link is interesting. It cannot be seperated from roll behavior. Now it is said to work with heave.. I am guessing this is suggesting pitch ? becuase if springs are already there, then what's the point?
Lotus was unusually open about trying a new internal suspension change this weekend, which suggests it is going down the path followed by Mercedes and having its system control roll as well as heave.
Let's see.
Although the E21 is externally similar to the 2012 car, the suspension package has been changed from that of its immediate predecessors.
The inboard elements of the suspension such as the anti-roll bar and torsion bar ends have been moved inside the footwell and are no longer easily visible when the nose cone is removed.
Ok
This is a common solution. The torsion bars, which are operated by the suspension rocker, do not attach rigidly to the chassis in order to provide the spring effect at the wheel. Instead, they react against each other.

This means the springs only work in heave and not in roll. This allows the team to set up the roll stiffness completely independently of the torsion bars.

We can also see the rockers use an element linking the bottom of the left rocker to the top of the right rocker.
They wont work in heave in that way, ie no spring force at all. If they were linked top to top then they will work in heave. As for roll, it will work, but that is dependent on the difference of wheel forces left to right. If the right wheel leaves the ground, the left side will collapse as there's no spring force whatsoever (remember no fixed corner springs? :mrgreen: ).
Now since you mentioned anit roll bars, then that may prevent collapse. However what's contradictory now is that you have a roll bar and your corner springs working like a roll bar as well. Having no spring effect for heave.
Unless the FRIC air spring is what is being suggested to support heave?

This is a solution that has been used in the past. Fitting a damper in this position provides damping of the roll motion. This, allied to a mechanical anti-roll bar, solely controls the stiffness and control of roll, again independent of the control for heave stiffness. This diagonally-mounted damper is the reason for the asymmetric bumps on the top of the chassis.
Fitting a damper there wil dampen roll, but it makes things worse for the "floating" torsion springs. They wont support each other predictably.
What Lotus may have done this weekend is replace both the front and rear roll damper and anti-roll bar with linked hydraulic elements.
Ok, we'll see if this all adds up. It's a bit hard to follow what is being said here. It's taking me round the mulberry bush trying to figure it out.
For Sure!!

Huntresa
Huntresa
54
Joined: Sat Dec 03, 2011 10:33 am

Re: Lotus E21 Renault

Post

Well one thing is sure we know Lotus has put alot of work into their suspension over the years, or atleast past 2 years cause its getting ever clsoer to being a real diffirentiator, seeing how close the cars are in terms of aero and other departments, atleast the top guys.

Swe tv had a nice piece on it where they visited Öhlins who help Lotus with their stuff, but ofc they didnt actually say anything, just showed difference between Pull and Push rod and stuff like that.

Crucial_Xtreme
Crucial_Xtreme
427
Joined: Sat Oct 15, 2011 11:13 pm
Location: Charlotte

Re: Lotus E21 Renault

Post

ringo wrote:
Hmm, change of tune.. FRIC went from no springs, all hydraulic and air, to everything mechanical.
The hydraulic over mechanical link is interesting. It cannot be seperated from roll behavior. Now it is said to work with heave.. I am guessing this is suggesting pitch ? becuase if springs are already there, then what's the point?
To be fair I don't think this is a change of tune for Craig. I believe he's maintained all along that Renault that reintroduced the concept(hydraulically linked) in 2009 and Mercedes have simply taken it a step forward. There was never any mention of "FRIC" or hydraulically linked suspensions last year in the "mainstream" media, yet Scarbs blogged about it. It went unnoticed until this year as if it were something new on the car when it has actually been used for multiple seasons. So I think you're mincing what the mainstream media has picked up on in 2013(years late btw), and their(German) name FRIC for the system, with what Scarbs blogged about back in 2011 in regards to Lotus.
So you must understand FRIC & everything(non mechanical) with it is a "2013 designation" of the Mercedes. This has nothing to do with, as you assert, Lotus who used the system first but is only now catching up(?maybe surpassed?) with Mercedes.

In case I wasn't clear enough:

2009: Renault/Lotus reintroduce hydraulically linked suspension(front to rear) to prevent dive under braking

2011: Mercedes took the simple(Lotus) front-to-rear interconnected system and developed it into a fully integrated system, totally replacing the car's conventional suspension.

2013: The German media get word of the development and dub it 'FRIC'(front & rear interconnected) which shouldn't be confused with the system Renault introduced which still uses/d mechanical parts.

It was most likely Renault that reintroduced the concept back in 2009. Its system was simple, merely linking the front and rear suspension together with hydraulic elements. This set-up worked on top of the conventional mechanical suspension and only controlled pitch, preventing dive under braking and squat under acceleration.

Being quite a simple solution, it was widely copied and now most of the current teams use it. But this is far from the fully interconnected system that the active era allowed, as it does not provide roll control.



Mercedes then took on the simple front-to-rear interconnected system and developed it into a fully integrated system, totally replacing the car's conventional suspension.

It was introduced in 2011 and has been on the car ever since. The system has been dubbed 'FRIC' by the German press, but it's not clear if this is the team's own term. It's something of a misnomer as the simpler Renault-style systems are front to rear connected. Rather the Mercedes system links all four corners of the car, controlling roll and pitch, not just individually but combining the effect when the car is in both roll and pitch simultaneously.

In concept and layout the FRIC system is simple. At each end of the car there are three hydraulic elements: a pair of elements attached to each pull/pushrod rocker control roll and a centre element linked to both rockers' control pitch. Each of these elements is linked left to right and front to rear.
The heave elements, shown in green, link front-to-rear to control dive under braking. The roll elements, shown in yellow, link side-to-side for antiroll.


Image
via AutoSport

When the car brakes, weight shifts forwards and the front suspension compresses and the rear rises. The pressure builds up in one side of the centre element on the front suspension, and this pressure in the hydraulic fluid is transferred to the rear centre element.

This increases the spring effect at the front and reduces it at the rear, which means the car will not dive nose down under braking. The car's ride height will remain more consistent for better control of the front wing and diffuser aero.

When the car rolls in a corner, the outer hydraulic elements will compress and the inner elements will rise. With the same effect as when the centre element is in pitch, the hydraulic fluid is transferred from one side to the other to increase the spring effect preventing the car rolling.

Both of these systems replace the springs and dampers of a normal suspension, so the system solely relies on the hydraulic fluid to hold the weight of the car. The fluid is therefore kept at high pressure within the hydraulic elements and pipework. Images of the front of the car with the nose removed show the ends of these hydraulic connectors to allow the system pressure to be topped up.

Although outwardly simple the system has far more complexity when the detail is looked at. The system needs to incorporate flow control valves to provide the spring and damper effect of conventional suspension; accumulators are needed to account for the change in volume of fluid in the system when the temperature varies.


Image
via AutoSport

But perhaps the biggest complexity is when the team starts to link the roll and pitch circuits together. It's possible that the system could be used simply to control pitch and roll separately, but the car is rarely in just one of these modes.

For example under heavy braking into a slow corner, the car will pitch from the braking and then roll as the steering is turned; this mode is known as warp.

In this condition you would want the pitch control to be good, preventing dive. But you would like a little roll to induce some mechanical grip.

If the pipework linking the centre elements could switch a valve to reduce the fluid transfer in the roll hydraulics, you could tune warp stiffness for slow corners. Conversely, the roll control in fast turns when braking is lighter so can be set to a stiffer setting for more aero control, which is critical in high speed corners.

With this sort of interconnectivity many different modes could be designed into the system's valving. As long as the valve switching is created by pressure differentials in the system then it is legal. The beauty of FRIC is that it is totally passive and beats all the rules introduced to ban active suspension.

It is of course quite easy to get lost in all of the potential complexity of the system. It certainly appears that Mercedes has spent some painful years setting up its FRIC system and its pace this year is probably as much to do with improved aero as getting the FRIC system tuned in.

AUTOSPORT understands that no other team has removed its mechanical suspension, as anti roll bars and torsion springs are still evident.

So Mercedes has the march on this technology. Its lap time advantage will vary by track but a couple of tenths is the likely gain. For many teams the investment is going to be hard to justify, compared to a relatively cheap proven mechanical suspension.



Link

First mention of hydraulically-interconnected system ever
Last edited by Crucial_Xtreme on Mon Apr 29, 2013 9:29 am, edited 1 time in total.

User avatar
ringo
231
Joined: Sun Mar 29, 2009 9:57 am

Re: Lotus E21 Renault

Post

It's still the same obfuscation over and over again, just more words.
Hydraulic fluid cannot behave like a spring. And i'm seeing that in this article.
We understand the intent of the system, which is communicated quite well, however the functionality of it is quite vague from these articles.

"Pressure builds up and increasing the spring effect" just sounds categorically wrong. We know something that is in-compressible, like hydraulic fluid, cannot behave like a spring. This article is just gluttonously careless.
It's a nice feast for the eyes yes.
so the system solely relies on the hydraulic fluid to hold the weight of the car.
What the he... :shock:
This is illegal. basically there's no sprung mass; all unsprung.
The system needs to incorporate flow control valves to provide the spring and damper effect of conventional suspension;
#-o
accumulators are needed to account for the change in volume of fluid in the system when the temperature varies.
If this part is true, I feel the accumulator is doing more than that. It's basically a loophole. It's powering the suspension. Providing additional energy to the suspension. The loop hole is the time factor. The suspension will behave like it is externally powered once the accumulators are activated. I don't know how the team controls them though, as they will only release energy when the pressure goes below a certain point. But i'm of the mindset this may be tuned to certain forces experienced in certain turns.
The suspension is powered externally, but that power was provided by the suspension itself, but at an earlier time.
This is what i gather from the use of an accumulator.
They can also be the main springs, if we ignore the error of placing that responsibility on some valves and hydraulic fluid. In fact they could have actual springs in them and not air.
For Sure!!

Kansas
Kansas
-5
Joined: Fri Feb 01, 2013 2:53 am

Re: Lotus E21 Renault

Post

Im glad they didnt waste time on DRD.

Its crucial to improve the current package.

The setup window is too small for E21. According to AMuS, it was due to the FRIC system.

It tooks 3 races for Romain to get it just right. While Kimi managed to hang on (except Malaysia), his comments after practices had not been convincing. In China he said the car changed everyday despite the setup remain the same. In Bahrain, he said that he wasn't happy with the car handling.

Seems to me, they need to understand the fundamental of the car more to extract better performance out of the car consistenly.

tony77g
tony77g
38
Joined: Fri Feb 08, 2013 11:47 am
Location: Italy

Re: Lotus E21 Renault

Post

ringo wrote:
"Pressure builds up and increasing the spring effect" just sounds categorically wrong. We know something that is in-compressible, like hydraulic fluid, cannot behave like a spring. This article is just gluttonously careless.
It's a nice feast for the eyes yes.
In landing gears of the aircraft operation is the same, and the hydraulic fluid and air like a spring

stefan_
stefan_
815
Joined: Sat Feb 04, 2012 11:43 am
Location: Bucharest, Romania

Re: Lotus E21 Renault

Post

Lotus testing new upgrades at Duxford

Davide Valsecchi was behind the wheel of this year’s Lotus car, and made a testing program planned for some time.
There were a lot of talking that Lotus will check DRD (drag reduction device) before Spain but pictures collected by f1talks.pl do not seem to confirm that suggestions. During the two days of tests, the first of which was a rainy, new front wing and floor were checked.

Image

New Vertical slots appered at the back of E21 front wing in front of the tyre. The shape of the floor at the height of the driver’s seat has been modified.

Sensors location suggests that the Lotus engineers have devoted much attention to examining the air flow around the rear tyres. Tightness of space between the edge and the diffuser is crucial for downforce at the rear axle.

Image

Closed air intakes and free space under the rear wing suggest that DRD wasn’t the main purpore of this aero test.

Image

Interesting is that E21 was running with really agressive/high rake at Duxford. We have never seen Lotus car with this kind of setup. Car with this amount of rake can generate hell a lot of rear downforce. Only problem is to manage ride height thru race distance. Having good tuned FRIC onbard is not a problem anymore.
via F1 Talks
"...and there, very much in flames, is Jacques Laffite's Ligier. That's obviously a turbo blaze, and of course, Laffite will be able to see that conflagration in his mirrors... he is coolly parking the car somewhere safe." Murray Walker, San Marino 1985

User avatar
Blackout
760
Joined: Tue Feb 09, 2010 3:12 am

Re: Lotus E21 Renault

Post

Crucial_Xtreme wrote:http://cdn.images.autosport.com/editori ... 452944.jpg
image via XPB

Although the E21 is externally similar to the 2012 car, the suspension package has been changed from that of its immediate predecessors.
The inboard elements of the suspension such as the anti-roll bar and torsion bar ends have been moved inside the footwell and are no longer easily visible when the nose cone is removed.
via Craig Scarborough

Link
That's what I said about three weeks ago :mrgreen:

Found a HR pic showing the steering rack, the right rocker and 3 other elements. could be the grey one in the middle a heave spring ? Scarbs says the dismounted "gold damper–like device, which is the key component that Lotus has run with since Germany 2009...is the hydraulic link element and is hydraulically connected to a similar device in the rear suspension". don't they need inerters anymore ? What's the thinner grey element behind the rocker ?

Image

Crucial_Xtreme
Crucial_Xtreme
427
Joined: Sat Oct 15, 2011 11:13 pm
Location: Charlotte

Re: Lotus E21 Renault

Post

tony77g wrote:
ringo wrote:
"Pressure builds up and increasing the spring effect" just sounds categorically wrong. We know something that is in-compressible, like hydraulic fluid, cannot behave like a spring. This article is just gluttonously careless.
It's a nice feast for the eyes yes.
In landing gears of the aircraft operation is the same, and the hydraulic fluid and air like a spring
+1

User avatar
Blackout
760
Joined: Tue Feb 09, 2010 3:12 am

Re: Lotus E21 Renault

Post

Kansas wrote: It tooks 3 races for Romain to get it just right. While Kimi managed to hang on (except Malaysia)
Yeah 'Grosejan is a bad driver and Kimi is far better'. we inderstood you. no need to allude to it every time you come here. It's wrong, the ways you do it is ridiculous and this thread is about the car.
stefan_ wrote:
Lotus testing new upgrades at Duxford

Davide Valsecchi was behind the wheel of this year’s Lotus car, and made a testing program planned for some time.
There were a lot of talking that Lotus will check DRD (drag reduction device) before Spain but pictures collected by f1talks.pl do not seem to confirm that suggestions. During the two days of tests, the first of which was a rainy, new front wing and floor were checked.

http://www.f1talks.pl/wp-content/upload ... uxford.jpg

New Vertical slots appered at the back of E21 front wing in front of the tyre. The shape of the floor at the height of the driver’s seat has been modified.
via F1 Talks
The view angle fooled them; what they describe as a floor modification is just the tea-tray
The Front wing isnt new either

stefan_
stefan_
815
Joined: Sat Feb 04, 2012 11:43 am
Location: Bucharest, Romania

Re: Lotus E21 Renault

Post

Blackout wrote:The view angle fooled them; what they describe as a floor modification is just the tea-tray
The Front wing isnt new either
It seems so. Seen from below. The driver position part isn't a thing to mention either, because I remember Prost being a little bit high at last year's YDT in Abu Dhabi, but that was just because he didn't had a proper seat or something like that.
"...and there, very much in flames, is Jacques Laffite's Ligier. That's obviously a turbo blaze, and of course, Laffite will be able to see that conflagration in his mirrors... he is coolly parking the car somewhere safe." Murray Walker, San Marino 1985