LMP front diffusors

[templer]

If I look at the front diffusors of the new LMP cars i see a lack of strakes compared to the old LMP 900 versions.
Does anybody have an idea why the newer cars need no strakes.

[AU N EGL]

Most LMP cars have three diffent front diffusers; Low, medium and high downforce.

[pirenzo]

Possibly they're just a bit out of favour. I recall the early front diffusers also having no strakes.

I think the front diffuser design is pretty much free, so if they're running without strakes there must be a benefit.

[Aysedasi]

Humour me guys - what's a strake?

[bludvl_x19]

I'm thinking that they are the 'lil winglets on the outside of the guards. . . but I stand to be corrected.

Mick

[zac510]

No, a diffuser strake is like a vertical 'fence' within the diffuser. As usual mulsannescorner is the best place for a picture.
From my basic knowledge, sometimes it may be used to guide air out of the diffuser and sometimes it may be used to stop air moving sideways in the diffuser so on this basis it's sure to be dependent on the whole shape and design of the car rather than the simple diffuser shape.

[bludvl_x19]

And I now resume my seat

Mick

[MulsanneMike]

Originally Posted by templer

If I look at the front diffusors of the new LMP cars i see a lack of strakes compared to the old LMP 900 versions.
Does anybody have an idea why the newer cars need no strakes.

Form follows function so the guys in the wind tunnels clearly are coming to a similar conclusion and don't like what they see. Could have a lot to do with the verticies shed having negative impact on airflow to the spec. tunnels.

Here's a shot of a strake, Lister's Strakearama:

http://www.mulsannescorner.com/listerstormlmp-8.html

[templer]

Hello Mike

i knew your Lister pic. If I have understand Peter Elleray right in the great book " Bentley at Le Mans" the strakes on the Bentley EXP Speed 8 2002 and especially on the Speed 8 have much to do with the tunable front downforce.
At Le Mans Bentley drove with less strakes as in Sebring for less downforce.
With the new 2004 rules the general front diffusor layout didn't change . THe only new thing is the 50mm step in the middle which lead much more air under the car then the old one. So I have to look carfully to get this air out of the car. I think this is a point Dome or Porsche have spend a lot of time in tunnel to get a good airflow from the diffusor to the exaust in the sidepods as Peter Ellerary have said this i a very critical part for the downforce figures. ( Compare the problems with the R8C mentioned in the book above).
And the new car splitters like the Porsche ( www.mulsannescorner.com/PorscheRSSpyder-2.html) or the Dome ( www.mulsannescorner.com/newsmarch08.html) don't have strakes outboard or in the middle part. Both have only two inboard the front wheel which separate the inner area from the outboard section. So I am a little surprised cause the front is the only part which is not too regulated.

( Can't wait for your Peugeot thread)

Best regards

Markus

[AU N EGL]

Originally Posted by templer

Hello Mike

i knew your Lister pic. If I have understand Peter Elleray right in the great book " Bentley at Le Mans" the strakes on the Bentley EXP Speed 8 2002 and especially on the Speed 8 have much to do with the tunable front downforce.


Markus

To my understanding that is correct. under body air flow expecilly on high speed corners needs to be contained. Those straikes or upside down fish dorsal fins help with just that.

[Robert RS]

3.6.2 - No aerodynamic element can be added on the bodywork
apart from :
- Two aerodynamic elements maximum at the front of the
front fenders provided that :
• They do not obstruct the driver's view
• They do not mask the headlights ;
• They are not situated more than 600 mm above the
reference surface ;
• They are approved by the manufacturer and the
ACO (homologation form of the car).
- One “Gurney” at the rear of the bodywork.
- The rear wing described below.


Regards,

Robert

[MulsanneMike]

Originally Posted by Robert RS

3.6.2 - No aerodynamic element can be added on the bodywork
apart from :
- Two aerodynamic elements maximum at the front of the
front fenders provided that :
• They do not obstruct the driver's view
• They do not mask the headlights ;
• They are not situated more than 600 mm above the
reference surface ;
• They are approved by the manufacturer and the
ACO (homologation form of the car).
- One “Gurney” at the rear of the bodywork.
- The rear wing described below.


Regards,

Robert

Yes, but 3.6.2 has been on the books in that form for some time (pre LMP2004 regulations):

From 2001 LMP900/675 regulations:
3.6.2 - Forward of the front wheels centre line, only bodywork panels having parallel planes and a constant thickness are permitted.
Two aerodynamic elements maximum can be added in front of the front fenders provided that :
· They do not obstruct the driver's view
· They do not mask the headlights ;
· They are not situated more than 600 mm above the plane generated by the flat bottom.
· They are approved by the manufacturer and the ACO (Homologation form of the car)

[pirenzo]

Wouldn't the front diffuser be defined within the regulations as part of the floor, rather than bodywork, and hence exempt from 3.6.2?

[MulsanneMike]

Originally Posted by pirenzo

Wouldn't the front diffuser be defined within the regulations as part of the floor, rather than bodywork, and hence exempt from 3.6.2?

That would certianly be my take...

[minimangler]

Originally Posted by pirenzo

Wouldn't the front diffuser be defined within the regulations as part of the floor, rather than bodywork, and hence exempt from 3.6.2?

Agreed.

Perhaps, like happened with the original era of diffusers, when we had a raft of crazy massive tunnels (remember that Rondeau?) that were steadily brought back down even before rules adjustments, we are seeing designers realising that less can be just as much?

[Aysedasi]

Thanks for the explanation guys.