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Brabham BT44 skirts


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#1 Teapot

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Posted 26 August 2012 - 16:02

Could someone explain me how what Gordon Murray described as a " transverse,vee-shaped, sacrificial skirt" worked on the BT44? I understand that it was designed "to exclude air from going under the car and producing lift" but actually "created a low pressure behind it". It sounds quite different from the more advanced sliding skirts, but still I have no idea about what it looked like (the "transverse" thing baffle me) and neither Google nor the search facility helped this time!

Thanks in advance!

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#2 kayemod

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Posted 26 August 2012 - 16:40

This is just hearsay from a Lotus mechanic, but Gordon fitted a transverse skirt, I think somewhere around the front axle line or possibly just forward of it, to his BT44 design some time towards the end of the 1974 season. I've never seen any photos or sketches of this, but I'd guess it was made from something like hinged Lexan, or a similar polycarbonate material. I know that Lotus had considered something like this themselves, but had concerns about legality, as it could have been classed as a moving aerodynamic devices. McLaren fitted a Lexan "scraper" ro the nose of their M23 at one stage, and there were mutterings about that, though as far as I know, it was never protested.

#3 MartLgn

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Posted 26 August 2012 - 17:34

There is a picture of a BT44 at Kyalami in Alan Henry's book on the Brabham Grand Pric cars which appears to show this skirt as nothing more exotic than 2 strips mounted amidships on the underside of the car to form an inverted V. The purpose of which seems to be to divert air out of the sides of the gap twixt car and track thus creating an are of lower pressure beneath the car.

#4 eldougo

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Posted 01 September 2012 - 06:19

No skirt photo i been looking ,however a tiro of BT44 at Monza (thanks goro). 1974 to keep us going.

Posted Image

Uploaded with ImageShack.usUnknown copyright.

Edited by eldougo, 02 September 2012 - 04:03.


#5 f1steveuk

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Posted 01 September 2012 - 06:41

I do have a drawing somewhere, and it did work, to a fashion. The skirts were well under the flat underneath of the tub and went to a point sort of midway at the centre point of the front axle line, out toward the outer edge of the tub, and then straight back to the trailing edge of the tub. As the car traveled forward, the air traveling around the skirted off area, was traveling faster than the "still" area within the skirted area, and created an area of lower pressure directly under the car.

If I get a chance, I'll go find the picture and scan it, although there may be a version in Sal's F1 Technology book or Gorgio's book?

#6 goro

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Posted 01 September 2012 - 07:52

This pic is from Italy GP
goro

Edited by goro, 01 September 2012 - 07:54.


#7 Michael Ferner

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Posted 01 September 2012 - 15:55

... and it's not a practice shot, either. It's from the first lap of the Italian GP, if I'm not mistaken.

#8 Duc-Man

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Posted 01 September 2012 - 16:11

Posted Image

I found this one on the web. I'd say Nürburgring '75.
Can't see any skirts underneath the car at all.

#9 Nigel Beresford

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Posted 01 September 2012 - 17:35

Could someone explain me how what Gordon Murray described as a " transverse,vee-shaped, sacrificial skirt" worked on the BT44? I understand that it was designed "to exclude air from going under the car and producing lift" but actually "created a low pressure behind it". It sounds quite different from the more advanced sliding skirts, but still I have no idea about what it looked like (the "transverse" thing baffle me) and neither Google nor the search facility helped this time!

Thanks in advance!


With all due respect, are you absolutely sure that you haven't somehow mis-recalled this, because for sure McLaren ran skirts EXACTLY like you describe on the M23, beginning in '74 or '75?

I only mention it because of the lack of any visual evidence of them (so far) on the BT44, and I recall them clear as day on the M23.

Just sayin'....

Thanks
Nigel

#10 f1steveuk

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Posted 01 September 2012 - 18:01

Your right Nigel, the M23 had a system much the same as I described for the BT44, but the BT44 did have it, if only I could find Giorgio's drawing!

Originally Brabham had a simple flap skirt that ran across the front of the underneath of the tub, but it was refined to include a pointed front edge and added sides to enlarge the 'low pressure' area.

I'm still looking for the drawing!!

#11 Nigel Beresford

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Posted 01 September 2012 - 19:59

FWIW here's what the McLaren skirts looked like. Although this is obviously from Brands '76, they were introduced (IIRC) in Austria 1975.

Posted Image

Photo credit unknown

#12 eurocardoc

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Posted 01 September 2012 - 20:34

Can't say as to the Brabhams, but several including Shadow ran similar set-ups the material was actually a preformed flexible plastic (don't know the technical name). It was moulded at maybe 30 degrees and was actually manufactured as a scraper for the conveyors in coal mines. Problem was as you might imagine, the start of a race with full fuel wore it down so by the latter point it became almost non effective. I recall most cars ran it down along the sides also in the period preceding those wonderful (sic) sliding skirts. Lotus of course ran the 'bristles'.

#13 Tony Matthews

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Posted 01 September 2012 - 21:04

Posted Image

M26, I think, and I may have a similar shot of an M23, but I haven't got time to search at the moment.