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The Lotus 49 and its derivatives


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#1 Spa65

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Posted 16 February 2013 - 21:27

I remember when this car first came out. Another revolutionary Chapman innovation - what could be more obvious than getting rid of the back half of the car chassis and bolting everything at the back onto the engine itself, surely the strongest and stiffest part of the car, and saving all that unnecessary weight associated with the rear half of the chassis. Helped make the 49 the only car on the grid to approach the minimum weight limit in 1967.

How many subsequent cars copied this obvious theme? Stewart's MS80 Matra in 1969 certainly looks like the rear half was all engine a la 49, but was it; and did any other F1 manufacturer copy this innovation once they got their Cosworth DFV V8's? Presumably their engines all had the necessary suspension and exhaust mounting attachments, though perhaps not where they would have ideally preferred them.

Or did the other DFV users use the engine as a main chassis member but with cosmetic non-load bearing rear panels to smoothe the airflow past the knobbly engine?

And what about the Lotus 72? Did that utilise the engine as the main stress bearer, or did the side radiators necessitate a beefed up rear chassis, so they reverted to a more conventional rear chassis? Perhaps by then they could get down to the weight limit without resource to half chassis? (Had to think a bit - what's the plural of chassis?)

I remember Rindt's comment in 1970 that he was driving a superior Lotus 72 and eveyone else was driving 49s. He thought that Brabham made the best 49. Was the Brabham a half chassis car along with others?

As an aside to this topic, why did Rindt requeat the 49 should be brought to Monza for the fateful 1970 event, when the 72 was clearly quicker, probably quite noticeably in a straight line, so would be the better mount at Monza? Did he have increasing concerns about the inboard brakes on a circuit where braking from top speed was the norm?

S.

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#2 Tim Murray

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Posted 16 February 2013 - 21:53

The Lotus 49 was not the first F1 car to use the engine as a fully-stressed chassis member - it had been preceded by others such as the Lotus 43, the BRM P83, Ferrari 1512 and Lancia D50. I'd be surprised if any DFV-powered F1 car didn't use the engine as a fully-stressed chassis member - I certainly can't think of one. What would be the point?

Edited by Tim Murray, 16 February 2013 - 21:53.


#3 Catalina Park

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Posted 17 February 2013 - 01:08

In what possible way did the BT24 not approach the minimum weight limit?

#4 Roger Clark

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Posted 17 February 2013 - 01:50

I'd be surprised if any DFV-powered F1 car didn't use the engine as a fully-stressed chassis member - I certainly can't think of one. What would be the point?

The Matra MS10?
The Brabham BT26A?

#5 Tom Glowacki

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Posted 17 February 2013 - 02:15

The Matra MS10?
The Brabham BT26A?



Raise you two:

Lotus 63
Matra MS 84.

#6 venator

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Posted 17 February 2013 - 03:23

While admittedly not F1 and not rear-engined, the front-engined Tatra cars and lorries from the early 1920s to the late 1940s used the engine as a stressed member, with the front suspension attached to the front of the engine, while the tubular backbone chassis was attached to the rear of it. There were others as well. Chapman was not as innovative as claimed, as he never patented this construction method, the reason being that it was already a known principle.

#7 Tim Murray

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Posted 17 February 2013 - 07:06

I'd be surprised if any DFV-powered F1 car didn't use the engine as a fully-stressed chassis member - I certainly can't think of one. What would be the point?

Yes, that was a silly thing to say. :blush:

The Matra MS10?
The Brabham BT26A?

Raise you two:

Lotus 63
Matra MS 84.

I should have thought of the 4WD cars, and the re-engined Brabham. However, although the Matra MS10 did have a tubular structure which enabled engine removal without disturbing the rear end, this structure made little or no contribution to chassis stiffness with the engine in place and may therefore be disregarded.

#8 Dale Harvey

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Posted 17 February 2013 - 07:16

The Brabham BT26A?
[/quote]

The BT26A was a space frame chassis and the photos in DCN's book on Jack clearly show that the chassis goes all the way to the rear. So the engine in this case is not stressed as in the Lotus 49.
Dale.

#9 Roger Clark

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Posted 17 February 2013 - 09:50

... the Matra MS10 did have a tubular structure which enabled engine removal without disturbing the rear end, this structure made little or no contribution to chassis stiffness with the engine in place and may therefore be disregarded.

What is the evidence for that?

Denis Jenkinson said in his description of the car: "in this car the Cosworth V8 engine is not (his italics) used as a chassis member and rear suspension carrier, for there is a tubular sub-frame bolted to the end of the cockpit monocoque, and running rearwards to a steel bulkhead, an alloy plate between the engine and the Hewland gearbox carrying the power unit on this framework"

Doug Nye said in History of the Grand Prix Car 1966-91, in a caption to a cutaway: "DFV was only partly stressed, note engine bay truss-tubes visibly alongside the engine, supporting beefy fabricated rear diaphragm just ahead of halfshafts on which rear suspension hangs".

#10 Tim Murray

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Posted 17 February 2013 - 10:51

I'm going by what Gérard Crombac wrote about the MS9/MS10 in his Profile of the Matra MS80 (Cars in Profile No 10):

But on the MS7, the engine was held by two extensions to the monocoque, like trousers legs, behind the main bulkhead. For the new Matra Formula 1, it had been decided to stick to this type of construction, hence the adoption of a 60° V12 configuration for the engine, which was narrow enough to fit in between the two "legs". However, the Cosworth V8 engine was wider, and as it had been stressed specifically to serve as chassis member, it was possible to attach it directly to the rear bulkhead, a disposition which had been pioneered by the Lotus 49. Bernard Boyer, the Matra chassis designer, was of the opinion that such an arrangement was going to make engine changes a lengthy business as he thought it would necessitate a complete resetting of the rear suspension each time, not to mention bleeding of the brakes. He decided therefore to incorporate a small spaceframe, which was not stressed to take suspension loads, but purely there to keep everything in place when the engine was out of the chassis. This frame was attached to a lyre-shaped boxed bulkhead around the gearbox to which the suspension was attached.


plus inspection of the MS10 cutaway drawing:

Just posted this Matra MS10 by Robert Roux in the "Matra" thread, might as well post it here too.
Posted Image

All I can see are two longitudinal tubes (DCN's 'truss tubes') running from the rear bulkhead on the monocoque to the fabricated bulkhead behind the engine. It may be that there was more to this subframe that is not shown in the cutaway, but if all it amounts to is the two longitudinal tubes on each side I feel that they would have contributed very little indeed to the torsional rigidity of the whole structure.

Edit: closer study of the cutaway shows a diagonal tube between the two longitudinal tubes, but even so, I still feel my point about torsional rigidity stands.

Edited by Tim Murray, 17 February 2013 - 11:03.


#11 mfd

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Posted 17 February 2013 - 13:33

In what possible way did the BT24 not approach the minimum weight limit?

I keep looking but I can't find it - who said this for you to pose the question?

#12 f1steveuk

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Posted 17 February 2013 - 14:33

I keep looking but I can't find it - who said this for you to pose the question?

In the opening post Mike.

I have always been lead to believe that the Lancia D50 had a "semi-stressed" engine, not a fully stressed.

I'm always perplexed by statements like "another Chapman innovation". In the case of the 49, did Maurice Philippe have more than a little to do with it? (the same with the 78/79, and Peter Wright and a raft of designers). As I have been told in many interviews with those that worked with Colin Chapman, he was a master at seeing what others had done, and developing it to the full, but he was fairly short on totally original ideas. The 25, the 43, the 49, 72,78 and 79 all seemed to fit the same story of those that worked with ACBC which went, "one day Colin came in to the office, and said he had seen something in a book/magazine/heard down the pub, and had made a sketch on a piece of paper/box lid/back of an envelope which I was told to go and draw up and include in the next car". Whatever, still a talent, but if you think really hard, did Lotus/Chapman ever come up with something 100% original? (Steps back and covers ears)

#13 kayemod

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Posted 17 February 2013 - 16:52

Whatever, still a talent, but if you think really hard, did Lotus/Chapman ever come up with something 100% original? (Steps back and covers ears)


I'm staying out of this, but define "100% original", how many people do you think have ever managed that? Your statement is a bit like saying that Bernie is "A fairly good businessman".


#14 Tom Glowacki

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Posted 17 February 2013 - 18:07

I'm staying out of this, but define "100% original", how many people do you think have ever managed that? Your statement is a bit like saying that Bernie is "A fairly good businessman".



One of these times, I'm taking my camera to the Badger Steam & Gas show, which takes place in August, not far from where I live. There are any number of 1930-1940's era tractors there with the front axle bolted to the front of the engine, the differential to the rear of the transmission case, and not a frame rail to be seen, the engine crankcase, transmission, and differential are the chassis, with the farmer plopped down on the seat, which is bolted to the diff case.

#15 f1steveuk

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Posted 17 February 2013 - 18:50

I'm staying out of this, but define "100% original", how many people do you think have ever managed that? Your statement is a bit like saying that Bernie is "A fairly good businessman".


Having worked for the wee one, he's not as good as you'd think!

Yes, to say 100% original would be very difficult, so the quantify it a bit, when you look at Lotus, they weren't really often the first, and quite often it wasn't actually ACBC's design. He may have had the germ of the idea (having been prompted by something he had seen), but Terry designed the 25 tub, Phillippe did the 49 design, Peter Wright took ground effect in to Lotus, Chapman had the courage to go for it. How much of the idea was Chapman's, on the back of an envelope, and how much was in reality the "designers" working for him, maybe taking a bit credit, I don't know, I spoke them all after Chapman's death!

#16 xj13v12

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Posted 17 February 2013 - 19:48

Read Peter Warr's book and this idea is answered in some detail. It was the application of ideas and elegant design that set Chapman apart. Many components had multiple uses and when he (and the team) got it right the result was something special. Often other teams picked up the ideas and created something better, the Williams FW07 for example.

#17 kayemod

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Posted 17 February 2013 - 19:54

Yes, to say 100% original would be very difficult, so the quantify it a bit, when you look at Lotus, they weren't really often the first, and quite often it wasn't actually ACBC's design. He may have had the germ of the idea (having been prompted by something he had seen), but Terry designed the 25 tub, Phillippe did the 49 design, Peter Wright took ground effect in to Lotus, Chapman had the courage to go for it. How much of the idea was Chapman's, on the back of an envelope, and how much was in reality the "designers" working for him, maybe taking a bit credit, I don't know, I spoke them all after Chapman's death!


Tony Rudd was Engineering Director when I was at Lotus. Out of earshot, he maintained that Colin wasn't really the genius that most of us thought he was, because "He made too many mistakes". All I know is that you could have been working on something for days, ACBC would pay one of his daily visits, look at what you were doing and say something like, "That's good, you're on the right lines, but if you did this...and this..." And he was almost always right. I've worked with a few clever people, but never anyone with the engineering intuition that man had. I can't really comment on what happened in the earlier years, but with the 78 and 79, I've always been convinced that the concept was pure Chapman, when The Great Man was distracted by more pressing things, Peter Wright came up with the 80. I worked with Peter, he's a nice bloke and very clever, but I never saw him as a self-starter. He was particularly good at progressing other peoples' ideas, though with Chapman deceased and out of the way, he tells a very good story about his part in Lotus ground effect thinking.


#18 RA Historian

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Posted 17 February 2013 - 22:47

The Lotus 49 was not the first F1 car to use the engine as a fully-stressed chassis member - it had been preceded by others such as the Lotus 43, the BRM P83, Ferrari 1512 and Lancia D50.

Yes indeed. The Lotus 49 stressed chassis/engine story is a myth that has been going around for years. I am pleased to see it once again debunked, but you know that we will hear of it again, and again, and again...

One of those racing "urban myths" that just will not go away.

Tom

#19 BRG

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Posted 17 February 2013 - 22:58

Was the DFV was the first racing engine designed from the outset to be used as a stressed member?

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#20 f1steveuk

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Posted 18 February 2013 - 09:51

Tony Rudd was Engineering Director when I was at Lotus. Out of earshot, he maintained that Colin wasn't really the genius that most of us thought he was, because "He made too many mistakes". All I know is that you could have been working on something for days, ACBC would pay one of his daily visits, look at what you were doing and say something like, "That's good, you're on the right lines, but if you did this...and this..." And he was almost always right. I've worked with a few clever people, but never anyone with the engineering intuition that man had. I can't really comment on what happened in the earlier years, but with the 78 and 79, I've always been convinced that the concept was pure Chapman, when The Great Man was distracted by more pressing things, Peter Wright came up with the 80. I worked with Peter, he's a nice bloke and very clever, but I never saw him as a self-starter. He was particularly good at progressing other peoples' ideas, though with Chapman deceased and out of the way, he tells a very good story about his part in Lotus ground effect thinking.


Funny you should say that, it was Tony who was the most verbal when I interviewed him. As for the 78/79, and quite how deep Peter Wright's input went, one does have to consider that it was he that did the sidepods on the March 701 for Specialist Mouldings, and conducted the initial experiments with BRM that spawned the full venturi concept. Having said that the missing detail was the sealing skirts, and Peter never did say whose idea that was!

#21 Nemo1965

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Posted 18 February 2013 - 10:15

Funny you should say that, it was Tony who was the most verbal when I interviewed him. As for the 78/79, and quite how deep Peter Wright's input went, one does have to consider that it was he that did the sidepods on the March 701 for Specialist Mouldings, and conducted the initial experiments with BRM that spawned the full venturi concept. Having said that the missing detail was the sealing skirts, and Peter never did say whose idea that was!


Mario Andretti recently said - in an interview- that HE was one of the people who inspired the ground effect car... He once tested a Lotus with soft springs, and he noticed that the grip increased tremendously to one side when the car was pressed to the ground at that side. But he is not the only one: when James Hunt was still at McLaren, they conducted experiments with plastic skirts attached to the side of the McLaren F1 car...

So the idea was around, and just as a previous poster said: it was Chapman genius that he put all the ideas that were floating around together... the venturi effect, the skirts... Chapman was the ultimate catalyst-engineer...

#22 kayemod

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Posted 18 February 2013 - 10:43

Funny you should say that, it was Tony who was the most verbal when I interviewed him. As for the 78/79, and quite how deep Peter Wright's input went, one does have to consider that it was he that did the sidepods on the March 701 for Specialist Mouldings, and conducted the initial experiments with BRM that spawned the full venturi concept. Having said that the missing detail was the sealing skirts, and Peter never did say whose idea that was!


Those side things on the 701 were just window dressing, they did very little, so the cars raced without them much of the time, aerodynamically they were nonsense. Peter had an obsession with blasting down straights and somehow staggering around corners, Chapman the exact opposite. I'm not trying to belittle Peter's contribution at all, but while undoubtedly clever, he was never an engineer in the sense that Colin was. I'm sure that PW sorted out things like tunnel shapes and venturis, but he was an aerodynamicist, those sliding skirts were an elegant engineering solution, they had 'Chapman' written all over them. Much of my work at Lotus was spent developing a vacuum moulding system, as Chapman saw it as the key to the company's future existence, he took a great interest in all aspects, visiting us almost daily to follow progress, he really understood things like seals and pressure differentials that were crucial to the process. Interestingly, after I left, Peter was put onto the VARI (Vacuum-Assisted Resin Injection) process, and I've read articles that credit him with much of its success. Although I've no idea how much of the credit Peter claims for himself, he actually came to the programme quite late in the day when it was more or less sorted.

#23 bradbury west

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Posted 18 February 2013 - 20:42

but Terry designed the 25 tub,.....


OT a little....Are you sure? My understanding is that the 25 was fully operational and racing prior to Len's return to Lotus, after ACBC had courted him for a while, including sending flowers and chocolates to Iris as an inducement. After producing some other work of his own, Len went back to Lotus at the end of '62, doing various projects for ACBC, including looking over in horror at Chapman 's misunderstood variant of Len's A frame as on the Terrier, which was on the Lotus Cortina, hence the wheel-cocking antics of the car, and his 2 page foolscap report on why the 30 would not work properly, a report which he still has to hand. Len went on to re-work the 25, later into the 33, and his crowning claim was to have been entrusted with the entire design of the legendary Indy 38 from a clean sheet of paper, Lotus' first full monocoque, Len having seen the full potential of the 25 but with the tub fully formed and enclosed, (perhaps as a consequence of his wartime RAF service) into which ACBC had no input as he was far away in the Southern hemisphere for that period.
Roger Lund

Edited by bradbury west, 18 February 2013 - 20:43.


#24 Doug Nye

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Posted 18 February 2013 - 20:55

Alan Styman did the donkey work on the original Lotus 25 design drawings. Len Terry - upon his return to Team Lotus - played a major role in developing it into a reliable and consistent race winner. There is much more to the 25-family story than has ever been recounted, and quite a high proportion of what has been published hitherto is either muddled, misleading or just plain wrong. In part thanks to the young... DCN

#25 VWV

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Posted 18 February 2013 - 22:19

Alan Styman did the donkey work on the original Lotus 25 design drawings. Len Terry - upon his return to Team Lotus - played a major role in developing it into a reliable and consistent race winner. There is much more to the 25-family story than has ever been recounted, and quite a high proportion of what has been published hitherto is either muddled, misleading or just plain wrong. In part thanks to the young... DCN


Sounds like a topic for a future article in Motorsport for the older DCN to set straight, hint hint..... :smoking:

#26 Ray Bell

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Posted 18 February 2013 - 23:04

Two outstanding cars in Australia (not F1, of course...) used the engines as stressed members...

The Clisby hillclimb car, based on a Douglas flat twin motorcycle engine with a simple tube backbone chassis was one, the other being the car it spawned, the Eclipse Zephyr by Eldred Norman. A Holden front crossmember shortened and bolted up to the timing gear area at the front of the block, a piece of steel tube flanged and bolted to the rear of the block and flanged and bolted to a Tempo Matador gearbox from which the rear suspension was hung.

What Chapman did, or someone did (possibly even being a Cosworth idea?) was use that neat triangular flexible blade to mount to the top of each cylinder head. A very neat and effective way of mounting the engine which allowed for the expansion of the hot bits in use without compromising the geometry or stiffness.

Was the BRM H16 designed to be a stressed member? If so, it predated the DFV as such an engine as would have the Lancia D50 engine.

#27 Tony Matthews

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Posted 18 February 2013 - 23:50

What Chapman did, or someone did (possibly even being a Cosworth idea?) was use that neat triangular flexible blade to mount to the top of each cylinder head. A very neat and effective way of mounting the engine which allowed for the expansion of the hot bits in use without compromising the geometry or stiffness.

That was a Keith Duckworth design, but may not have been original... Very neat, though.

#28 f1steveuk

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Posted 19 February 2013 - 13:26

Alan Styman did the donkey work on the original Lotus 25 design drawings. Len Terry - upon his return to Team Lotus - played a major role in developing it into a reliable and consistent race winner. There is much more to the 25-family story than has ever been recounted, and quite a high proportion of what has been published hitherto is either muddled, misleading or just plain wrong. In part thanks to the young... DCN


I was just about to write, "I'm sure I read it several times, not least in one of Doug's books!", but If I have been misled by one of the best, it's not a problem, I stand happily corrected.

Yes Regga', basically the story we got from Peter in our doco' interview, but he said to use "we noticed" intimating it was a joint discovery. Tony Rudd said he saw the drooping and wondered about sealing the gap, and there's probably a raft of names who'd happily take the credit!

#29 kayemod

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Posted 19 February 2013 - 13:53

Yes Regga', basically the story we got from Peter in our doco' interview, but he said to use "we noticed" intimating it was a joint discovery. Tony Rudd said he saw the drooping and wondered about sealing the gap, and there's probably a raft of names who'd happily take the credit!


When I said that the design of the Lotus 78 & 79 skirts were almost certainly down to Colin Chapman, I never doubted that it might have been Peter Wright and others who saw the need for a reliable and efficient means of sealing the gap, problem solving of that kind was the very thing that The Great Man was good at, better in fact than most in his employ. Peter's degree was I think in Mechanical Sciences, but although I'd never question his cleverness, he was good on theory but not terribly practical in a hands-on sense. I can only guess of course, but once Peter had identified the problem, it would have taken Colin's talents to come up with a workable solution.

#30 Tony Matthews

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Posted 19 February 2013 - 15:45

When I said that the design of the Lotus 78 & 79 skirts were almost certainly down to Colin Chapman, I never doubted that it might have been Peter Wright and others who saw the need for a reliable and efficient means of sealing the gap, problem solving of that kind was the very thing that The Great Man was good at, better in fact than most in his employ.

There were several people in the Drawing Office, and Martin Ogilvie, I'm sure, had something to do with skirt design. The method of sealing the gap went through various stages, getting more complicated, from simple brushes to a 'pocket door' system with longitudinal rollers, sprung levers and polythene sheet seals.

Posted Image
From 'Formula 1 Technology' by Peter Wright.

Edited by Tony Matthews, 19 February 2013 - 15:53.


#31 mfd

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Posted 19 February 2013 - 16:28

[Great discussion. Still OT, but it’s easy to go OT when talking about Chapman and Lotus and, frankly, it’s so much fun… ]

You might enjoy this Rega...Peter Wright on the T88 but also the backround through 76,77,78,79 & 80
http://www.grandprix...ft/ftpw021.html

#32 Tony Matthews

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Posted 19 February 2013 - 17:10

http://www.grandprix...ft/ftpw021.html

The rather grubby little illustrations of the components of the T88 were done by me, but coloured by someone else. I used the rather odd angle because that is the angle that Chunky sketched as he was explaining the design to me. Everything was done in a great rush, and I never saw the car, and didn't for years - it would have been nice to have done a cutaway of it.

There were a couple of other simple drawings done at the same time, one was a front view showing the second chassis maintaining a perfect position relative to the road, while the first chassis rolled hard to one side. I exagerated the amount of movement to make the point, but when a wag in the Drawing Office at Ketteringham saw it he said "Huh, obviously being driven by Jumper!"



#33 mfd

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Posted 19 February 2013 - 18:04

The rather grubby little illustrations of the components of the T88 were done by me, but coloured by someone else. I used the rather odd angle because that is the angle that Chunky sketched as he was explaining the design to me

Are they overlays Tony?

#34 Tony Matthews

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Posted 19 February 2013 - 19:17

They were not drawn as overlays, but could have been, and in fact I did a final version years later that combined most of them in one drawing. You have to appreciate that the whole thing was done in a frantic rush, from driving up to Norfolk from Hertfordshire in dense fog, in a Cortina Estate with what felt like no front brakes, waiting for two hours for ACBC to see me, a rushed brief, return journey, working all night and half the next day then delivering them to Ketteringham. All for ten bob. Happy days!

#35 CSquared

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Posted 19 February 2013 - 19:29

There were several people in the Drawing Office, and Martin Ogilvie, I'm sure, had something to do with skirt design. The method of sealing the gap went through various stages, getting more complicated, from simple brushes to a 'pocket door' system with longitudinal rollers, sprung levers and polythene sheet seals.

I would think that if this were done today, the skirts would be declared illegal movable aerodynamic devices. How come that wasn't the case in 1977?

#36 elansprint72

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Posted 22 February 2013 - 11:56

O/T but I found this interesting:


#37 mfd

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Posted 22 February 2013 - 12:10

O/T but I found this interesting:


The thing about YT, is it always leads elsewhere :D A lovely four minutes with Williams FW07 - & about the skirts!


Classic exchange between Jones & Williams at the end...

Edited by mfd, 22 February 2013 - 12:12.


#38 f1steveuk

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Posted 23 February 2013 - 12:57

Technically, in motorsport, it's not ground effect, as such. The whole point of the skirts was to seal the gap, thus creating a venturi underneath, but because of the ground, a venturi with only one curved surface. The analogy Peter used with us, was the inside of a carburetor, squashing the airflow down, and then speeding it up as it expands the other side, creating a low pressure area (which in a carb' draws fuel through).

#39 f1steveuk

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Posted 23 February 2013 - 18:54

It is correct they are based on completely different principles, but it’s not a misnomer for race cars to refer to it as ground effect, as in that case it happens too as result of the interaction with the ground. In airplanes the effect of the ground is mainly due to the reduction of the downwash angle, which results in less induced drag.


What he describes here - beside the fact that both application, carburetors and race cars, are based on the Venturi principle – is the effect of a diffuser. I wonder whether he saw it that way at the time.


I'm not sure that he did, I think it was Adrian Newey that saw that avenue of development.

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#40 gablet

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Posted 26 February 2013 - 07:29

Going back to the Lotus 49 itself and its development I would like to focus on the very first version, the 1967 car.
Many know that due to the fear of excessive oil consumption Chapman included an additional oil tank inside the cockpit, above driver's legs.
It was sometimes used depending on the race circuit: at the German GP for example.
Does anyone know something more about this tank and would like to share some image if have any?
Gab