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Lotus 49 Ducted Windscreen


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#1 Anorak Man

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Posted 21 February 2003 - 05:21

Does anybody know with certainty what the thinking was behind the duct on the Lotus 49 windscreen?

Was it to vent cooler air to the driver or aimed at smoothing the flow over the cockpit?

Was it a success?

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#2 Ray Bell

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Posted 21 February 2003 - 06:48

This was introduced, as I recall, on the Lotus 25... maybe the Lotus 24.

The idea was the create a jet of air over the driver's head and to reduce the windscreen height (IIRC) at the same time as it made the car more streamlined.

#3 Dave Wright

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Posted 21 February 2003 - 09:28

Ray is correct. The following is from an interview with Colin Chapman in Jan 1966 on the development of the Lotus 25/33.

Colin Chapman - The windscreen went through a change in 1963. The drivers were complaining of a lot of buffeting in the cockpit and, of course, to get the screen high enough to stop the buffeting would have reduced visibility, particularly in the corners. And so, in 1964, we went to the slotted type screen - a double - screen enclosing a converging passage in which the air is speeded up to emerge from the top in a high speed stream which deflects the ordinary air.

Charles Bulmer- A sort of jet-stream barrier to prevent the normal air-flow curling into the cockpit region quite so soon.

Colin Chapman - That's right. It meant that we could lower the leading edge of the screen by about two inches which improved visibility tremendously. The drivers were delighted. Then at Monza, last year, we put the old one back just to see if there was any measurable difference in drag. There wasn't, but the drivers said they couldn’t drive with the conventional screen after they’d been used to the slotted one.

#4 Ray Bell

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Posted 21 February 2003 - 09:56

I also recall a mention somewhere that they discovered that rain didn't take any notice of the stream of air... it hit the drivers in the face anyway.

DSJ?

#5 fines

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Posted 21 February 2003 - 17:37

That's why Graham Hill once (Nürburgring F2 '68?) used that strange 'propellor' visor!

#6 Garagiste

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Posted 21 February 2003 - 17:42

I remember seing a photo of that crazy visor. I thought at the time that the gyroscopic forces it produced must have been immense. How did he ever concentrate if his head kept wanting to go straight on at every corner? :stoned:

#7 Ray Bell

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Posted 21 February 2003 - 22:29

Mustn't have worked, I don't think he wore it the day he set fastest lap in the rain at Warwick Farm...

#8 eldougo

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Posted 21 February 2003 - 23:04

;)
(qoute)
Ray Bell Mustn't have worked, I don't think he wore it the day he set fastest lap in the rain at Warwick Farm...
Ray i seem to recall that some body did wear one of those vertical frizbee rain
shields at the "FARM" .However i can,t remember who it was it was about the
same time as HILL in the wet race. :up:

#9 Ray Bell

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Posted 21 February 2003 - 23:23

I'm fairly sure I associate Hill and that rotating visor with the BRM era...

But I'm open to correction.

#10 Roger Clark

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Posted 21 February 2003 - 23:49

Originally posted by fines
That's why Graham Hill once (Nürburgring F2 '68?) used that strange 'propellor' visor!


Did Hill drive F2 at the Nurburgring in 1968? The only time I can remember him using that visor was at Snetterton in 1964 (in a BRM of course, as Ray mentioned).

There were other cars that used the Lotus-like slotted windscreen. The ones that spring to mid are the P126/P133 BRMs (designed by Len Terry) and the early Matras (MS5, 7 and 10).

#11 Wolf

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Posted 22 February 2003 - 00:38

Rotating visor?!? I've never seen such a contraption. Anyone has a photo? Thanks in advance. :)

#12 dolomite

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Posted 22 February 2003 - 01:09

If this ducted windscreen thingy was so great why was it not used again after the 49?

#13 Rob Ryder

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Posted 22 February 2003 - 02:48

Roger is correct on Graham's spinning visor - 14th March 1964 Daily Mirror Trophy Snetterton.

..... and here is the beastie!

Posted Image

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(Photos from Motor Sport Magazine)

Rob

#14 Anorak Man

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Posted 22 February 2003 - 09:56

Ta Chaps!

Fascinating.

So I gather it was using the venturi effect to smooth the airflow over the cockpit.

That'll do nicely. And yes, I see it on the baby Lotuses too. I wonder why it's not being used today, since Jimmy and Graham liked it.

It just shows the sophistication of CC's thinking. Compare the 'pop-rivet' construction of the succesful 1976 McLaren with the previous decades Lotus 33. If you were to ask somebody who knew nothing about F1 history, I vouch almost all would say the McLaren predates the elegant Lotus.

Thank you for the images of Graham. Only he'd get away with wearing that thing with a straight-face eh? I could imagine him on 'Call My Bluff' passing it off as him testing the earliest Head-up display for the RAF.

I'm sure they were for-sale in the pages of the motorbike mags of the sixties.
Imagine the visibility, with a 1" donut sitting on the crown of your conk, and a half-inch supporting band running right along your sightline. And the whole idea is to IMPROVE viz. Potty!
At the speeds of British bikes in the 60's, I don't think it'd turn at all.

AM

#15 fines

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Posted 22 February 2003 - 11:46

Originally posted by Roger Clark
Did Hill drive F2 at the Nurburgring in 1968? The only time I can remember him using that visor was at Snetterton in 1964 (in a BRM of course, as Ray mentioned).

I didn't check! I just have this image in my head from a poster I had probably 15 or rather twenty years ago in my room, with Graham in a GLTL car that looked (from memory) too small for an F1.

Damn puberty! Why does one have to grow up and throw away one's childhood treasures... :mad:

#16 Mark A

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Posted 22 February 2003 - 18:12

BTW,

The rotating visor is pretty common in Karting (or was a few years ago anyway).

#17 Mark A

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Posted 22 February 2003 - 18:24

Found a picture.

Posted Image

#18 Doug Nye

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Posted 22 February 2003 - 23:14

The rotating visor as pictured was devised and/or marketed by none other than Lance Macklin, former HWM, Austin-Healey, Le Mans and Dundrod disasters etc driver - who based it upon the rotating 'clearscreen' wheelhouse window devices with which he was familiar on his father's Fairmile motor torpedo and motor gunboats, the family yacht, almost any relatively small sea-going craft.

DCN

#19 Wolf

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Posted 23 February 2003 - 01:05

Thanks alot, guys; both for photos and explanations. :)

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#20 joachimvanwing

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Posted 23 February 2003 - 01:25

Originally posted by Wolf
Thanks alot, guys; both for photos and explanations. :)

That visor is quiet popular in karting. We all use it in heavy rain.

#21 eldougo

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Posted 23 February 2003 - 07:16

:clap:
I bought one of them 3 years ago never been able to use it the drought has seen too that.

#22 Anorak Man

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Posted 23 February 2003 - 07:21

Originally posted by Doug Nye
The rotating visor as pictured was devised and/or marketed by none other than Lance Macklin, former HWM, Austin-Healey, Le Mans and Dundrod disasters etc driver - who based it upon the rotating 'clearscreen' wheelhouse window devices with which he was familiar on his father's Fairmile motor torpedo and motor gunboats, the family yacht, almost any relatively small sea-going craft.

DCN


Good Ol'Lance!

I bet he came up with an (equally bonkers) name for his invention ... Go on tell us Doug ...

And then sold the rights to Yankee 'Propeller- Head' Karters! :)

Sorry Chaps, couldn't resist.

AM

#23 Anorak Man

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Posted 23 February 2003 - 07:29

The Missus has come up with another question over breakfast. (Y'can tell why I love her eh?)

I don't recall seeing those clever (American!) NACA ducts on any GP motas before they appeared on the Lotus. They must've been used in sports cars before GP cars surely?

Anybody know the first racing car, and F1 car to incorporate them?

They must make a huge saving on drag compared to a scoop.

AM

#24 Ray Bell

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Posted 23 February 2003 - 09:46

An article in Motor Sport credited the first use of the NACA duct to the Vanwall IIRC... a Costin inclusion.

It's important to note, according to the article, that the exact shape and dimensions are critical for proper performance.

#25 Doug Nye

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Posted 23 February 2003 - 23:08

Try Connaught....built by ex-RAF officers, aeronautical engineers and one hugely experienced test pilot...

DCN

#26 Anorak Man

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Posted 27 February 2003 - 05:04

Originally posted by Doug Nye
Try Connaught....built by ex-RAF officers, aeronautical engineers and one hugely experienced test pilot...


And one was driven by that Lance Macklin bloke too! Not to mention Collins and Moss.

Accordingto this Atlas article by Mr. O'Keefe...

"In 1954, Formula One was going to a 2.5 litre standard and Clarke was scrambling to come up with a new engine and considered a V8 engine project being promoted by Leslie Brooks as well as a V8 engine from Coventry Climax. An entirely new car, which had some very advanced design elements (monocoque tub section with the V8 engine and a transaxle gearbox mounted in the rear and attached to the tub in the manner of the later Lotuses), was designed around the hoped-for V8 - it was called the Connaught J5 - but the whole concept fizzled when the so-called Coventry Climax Godiva V-8 project was shelved by Climax.

With the J5 project on the backburner, Clarke and his draftsman turned to work on another front-engined Connaught to be designated the B-Type and the first of that line was up and running by September 1954, too late for the 1954 season. The initial body-style was a streamliner, complete with NACA ducts, whose full-width bodywork covered the wheels, like the Mercedes-Benz W196 Stromlinienwagen introduced on July 4th 1954 at the French Grand Prix. It is fascinating that two companies as disparate in location and resources as Connaught and Mercedes-Benz could come up with the same concept at the same time. In the absence of a V8 being available, Clarke and Mike Oliver arranged for the 2.5 litre twin-cam four-cylinder Alta engine to be supplied exclusively to Connaught. Ultimately, Mike Oliver was able to squeeze about 240 bhp out of these Alta engines. The B-Type was to have Dunlop alloy wheels and servo-assisted disc brakes."