23 replies to this topic

[tyrrellp34]

Dear Friends from TNF!

I need information regarding the Ground effect Lotus cars from 1977 and 1978 like drawings, technical photos from the skirts or the whole bodywork.

Can you help me to clarify the follows:

When does Chapman first had the idea to make a car like that?

Did only Chapman gave some input to this project or was Peter Write involved too.

When did Lotus first tested the Lotus 78?

What was the (main) difference between the Lotus 78 and the Lotus 79?

Ok, maybe there was already a thread on TNF regarding this matter, maybe you can help me anyway..

[No27]

Originally posted by tyrrellp34


Ok, maybe there was already a thread on TNF regarding this matter, maybe you can help me anyway..

I'm pretty sure there was one that answers most of your questions. Otherwise try a google on the subject. There is at least one site that has the history of the idea well documented. The story on how the groundeffect idea was born is beautifull for it is essentially a simple idea.

[Rainer Nyberg]

A good story (with images) on the Lotus 79 can be found at http://www.ddavid.co...la1/lotus79.htm it is a site of a fellow TNF'er.

[Ray Bell]

My understanding is that the 78 'wing car' and the '79 'ground effect' cars were essentially very different...

[Cirrus]

As I understand it, the 78 was designed with wing-shaped sidepods (inspired by the DeH Mosquito) in order to achieve some downforce. The actual downforce generated far exceeded what should have been possible with wings alone. It was then appreciated that it was the acceleration of the air beneath the car that was creating a big pressure difference. The 79 was optimised to seal the sidepods to the ground, and to have sidepods shaped to generate a venturi profile to accelerate the air, rather than following a classical aerofoil shape. The rear suspension was moved inboard to give the air an easier exit path, and the monocoque was narrowed as much as possible within the constraints of contemporary construction techniques.

Peter Wright had been involved with a "wing car" project at BRM in 1969, and it is my understanding that he was instrumental in making ground effect work for Lotus.

[Ruairidh]

There are some very good sources for the story - Jabby Crombac bio of Colin; Theme Lotus by DCN; Tipler's book on the 78 and 79; Incandela's Anatomy and Development of the F1 racing car from1975; Lawrence's Colin Chapman: Wayward genius.

All tell variations on the same story.

Lotus in 1975 was in a funk. No drivers; uncompetitive car. Whether the idea came to Colin in Ibiza, or was the product of collaborative thinking involving Chapman; Rudd; Wright and Bellamy depends on who is telling the story but there was a 27 page brief and a team established to investigate the then dark science of downforce; negative lift and the impact of aerodynamics on handling.

The hope was another Chapman technical breakthrough; the "something for nothing" advantage. An investigative programme was started with Rudd; Wright; Bellamy and Mike Cooke and Charlie Prior all playing roles with work done at Imperial College and weekend debriefs with Chapman.

As thinking progressed there was a focus on the role of an inverted wing in the production of ground effect (a key influence was the De Havilland Mosquito's inner wing section) and on the day of Graham Hills funeral in December 1975 Tony Rudd received a message "the mosquito flies".

The T78 was first tested (per DCN) in August 1976, many of us may remember the "press embargo" that Peter Warr attempted to impose on the sneak pictures (Autosport ran the first one I saw) and the car was unveiled to the press in Dec 1976.

I'll leave the differences between the 78 and 79 to others more qualified than I am to answer - Incandela calls the 79 "another step further ahead of the 78-concept, exploring and using the venturi effect, with more downforce and less drag". DCN says the "main difference between the 79 and the 78 was that the side pods could now be changed, thus enabling the use of different underbody profiles, in order to provide the right amount of downforce, and also the correct distribution of the download".

[Eric McLoughlin]

How was the Mosquito influential in inspiring "downforce"? I would think that the inspiration from the Mosquito was in the idea of having radiators mounted in aerofoil section fabrications.

I think it is often overlooked that the 1970 March 701 also had aerofoil shaped sidepods - although they were relatively crude and the aerodynamic drag they created probably negated any benefit from aerodynamic downforce they might have generated.

[Ruairidh]

Originally posted by Eric McLoughlin
How was the Mosquito influential in inspiring "downforce"? I would think that the inspiration from the Mosquito was in the idea of having radiators mounted in aerofoil section fabrications.

That is probably a correct clarification.

Again, I'll leave it to others more technically competent than me to talk more on this, but my understanding was that the Mosquito directly influenced the radiator siting on the T78 and that was a key factor in the overall effectiveness of the first wing car.

Incidentally Crombac quotes Rudd as saying that indirectly the Lotus team discovered that heating the air created thrust.

[cheesy poofs]

You could also add the ( wingless ) Lotus 80 to your research. This was supposed to be Chapman`s evolution to the 79.

[Patrice L'Rodent]

Eric, I always thought the March 701 was so near and yet so far. If only they had fitted side fences to the pods!
Pat D'Rat

[Ruairidh]

Originally posted by Eric McLoughlin


I think it is often overlooked that the 1970 March 701 also had aerofoil shaped sidepods - although they were relatively crude and the aerodynamic drag they created probably negated any benefit from aerodynamic downforce they might have generated.

I don't think folks overlook the 701 (it is hard to ignore those sidepods) just that there is relatively little reported influence between that unskirted design and the later Lotuses (although Tipler does quote Mario as referring to the 701's when talking about what he wanted out of the T78 "downforce without drag penalty".)

IIRC there was also an article in Motor circa 1978 about an Indy car that seemed to have similar design theory to the 78.

[Eric McLoughlin]

Were the sidepods on the 701 also fuel tanks?

[Ruairidh]

Originally posted by Patrice L'Rodent
Eric, I always thought the March 701 was so near and yet so far. If only they had fitted side fences to the pods!
Pat D'Rat

I wonder. Perhaps all more downforce would have done would have been to show up the "problems inherent to the car's design" referred to by the wee Scot as early as Febuary of 1970. Mind you, if this aspect had worked maybe someone would have taken note, maybe not.

One of the interesting things about the initial years of ground effects was the understanding of the effect of those aerodynamic forces on the rest of the car. Which is one of the reasons why the T79 was uncompetitive the year after it dominated the field in 1978 - it got left behind as a package.

[Macca]

The thing the Lotus 78 and 79 and the March 701, and also the unfinished 1969 BRM, had in common was Peter Wright - it was his pet project.

The 701 sidetanks were just that, but maybe with a little downforce; the BRM blueprint appeared in Motor Sport a year or two ago, and that looked as though it wouldn't have given much downforce either.

The Lotus 78 had one fuel tank behind the driver and another sticking out each side (there was a fuel cell capacity limit which was waived for the 79); the side tanks had a wedge-shaped front to form a ramp for the radiator exits, and the underside was raised and curved to form part of an aerofoil profile. The side pod bodywork formed the forward and rear parts of the aerofoil, but the shape was fixed by the fuel tank; also, for some reason the skirts (which replaced the original ineffective brushes) were quite short.

The 79 had a single fuel tank and a slim monocoque, so the aerofoil/venturi shape was formed only by the sidepod, and the low-pressure area extended all the way back to the rear axle line, as well as the rad outlets being a better shape and the skirts extending further forward, and different profiles could be tried. As well, the front and rear suspension obstructed the airflow less than on the 78.

PWM

[Ruairidh]

Originally posted by Macca
The thing the Lotus 78 and 79 and the March 701, and also the unfinished 1969 BRM, had in common was Peter Wright - it was his pet project.

I missed that pretty big piece of this puzzle. When was Wright at March?

[Macca]

He was actually at Specialised Mouldings, the GRP specialists, where he had gone during the big exodus from BRM in late 1969 after Tony Rudd left, and was commissioned to do the sidetanks for the 701 because IIRC Robin Herd was too busy to do a design.

PWM

[Ruairidh]

Originally posted by Macca
He was actually at Specialised Mouldings, the GRP specialists, where he had gone during the big exodus from BRM in late 1969 after Tony Rudd left, and was commissioned to do the sidetanks for the 701 because IIRC Robin Herd was too busy to do a design.

PWM

OK, now I get the connection. Interesting that it is not much referred to in many of the Lotus books (unlike the BRM connection). Tipler has a section on this, confirming that it was Wright's suggestion that inverted aerofoil sidepods be used to solve the fuel housing issue for the 701. Tipler also cites Colin Crabbe's McLaren M7C as run for Vic Elford as another early forerunner of this idea.

Prof Lawrence (in his bio of Colin Chapman) also refers to Wright's design of the 701 body. Lawrence goes on to quote Robin Herd: "Every team gets daft ideas from fans. One of the daft ideas we got was that if we blanked off the aerodynamic sidepods on the 701 we would have a car which was sucked to the ground. Just as well we ignored such suggestions!"

[Eric McLoughlin]

I'll have to read Lawrence's book again. I must have raced through it when I bought it the Christmas before last. I'd forgotten all about the 701 details.

[mat1]

Originally posted by Macca

The Lotus 78 had one fuel tank behind the driver and another sticking out each side (there was a fuel cell capacity limit which was waived for the 79);

What do you mean by "waived"? Didn't they have to adhere to the rules, or was the rule changed?

mat1

[Rainer Nyberg]

Yes a rule change IRRC.

You were allowed to hold all the fuel in a single tank.

[tyrrellp34]

Thank you very much to all of you!

[dolomite]

Here is the drawing of Peter Wright's 1969 BRM ground effect design

[Ray Bell]

Wouldn't that have looked great at the time?

[Peter Morley]

Here is a picture of one of the Lotus 78 wind tunnel models - apparently they built 3 of them.
One with adjustable front wing, one with adjustable sidepods and this one with adjustable rear wing.
As you can see it was based on the 77 (e.g. the nose), presumably it could be said that the 78 was a development of the 77.