Patently Obvious: The Lotus 25


A&R articles are derived from many sources of inspiration. Primarily these are: –

  • Critical analysis of Colin Chapman’s engineering /automotive design ; by reading and studying established authors in the subjects of engineering, motor racing and design
  • Research
  • Review, re-evaluation and re- interpretation
  • Benchmarking through estimation of peer competition establishing  the impact of Chapman /Lotus design. This is typically achieved by studying the connectivity of the benchmark designs set out below.
  • Prompts by events and current circumstances that connect or establish links.

On this occasion the editor was researching the Type 25 and became aware that Colin Chapman was able to secure a patent on his monocoque design. This posed interesting questions and begged further analysis .As a result the editors have sought to provide an interpretation of the design and the context surrounding its design along with an estimation of its success.

In our study/ comparison of Chapman and Bugatti [see A&R article] it was explained that Bugatti held numerous patents we can now proceed to explain those taken by Chapman.

Design and patents form the basis of invention ,engineering, wealth creation, sustainability [through the elimination waste / duplication/ inefficiency] welfare and social justice. Therefore it is particularly appropriate that it be discussed in the Chapman and wider context for our subscribers and users of the proposed CCM&EC who may become involved directly

The editors believe it important that original sources be consulted wherever possible. Furthermore the investigation of the Patent Office/IPO has revealed further Chapman and Lotus patents. These have considerable implications and will be the source of a forthcoming article.

Chapman /Lotus Benchmarks

Our subscribers will have opinions on this but in the editors estimation the following are ground braking and in most cases both commercially and competition successful.

  • Mk.VI
  • Mk.VIII-Eleven
  • Elite
  • Elan
  • Type 25. FI car 1962-1965 Monocoque
  • Type 49.FI car 1967-1970 Ford -Cosworth
  • Type 72. FI car 1970-1975
  • Type 78/79. “The Wing Car” 1977 & “Black Beauty” 1978
  • Type 86-88. “Twin chassis” test car, 1980 & Lotus 88 FI car 1981
  • Type 111. Elise. 1996

Nye observes:-

“The twenty-fifth Lotus model had a more profound and far reaching effect upon the development of Grand Prix chassis design than any other single model in history”

The Fixed Parameters

These were the elements that Chapman was unable to alter significantly: –

  • The Regulations of 1961 governing FI motor racing [nb impacting uniformly on all competitors]
  • The Coventry Climax engine
  • Tyres [although evolving quickly and with which Chapman would experiment including permutation of wheel size]. Essentially they were providing better grip. Chassis and suspension interaction could exploit this.
  • Driver. Chapman was contracted with Clark and his driving style was quantified

Chapman is likely to have deducted that: –

  • The contemporaries would go with space frame chassis [see tabulation below]
  • The majority would use the same Coventry Climax V8 engine
  • That tyres would play a significant role in conjunction with superior handling
  • That Clark had a sophisticated light driving styleEssentially there would be little to separate the competition and they would conform to a common denominator and possess near identical performance
  • The strength of the Coventry Climax engine was such that it might be incorporated in the chassis
  • Therefore what was required to differentiate Lotus would be a superior chassis integrated and complementary with the tyres and Clark driving

It was said of Chapman: –

“Colin Chapman was one of the few who fully appreciated the importance of chassis layout and rigidity, suspension design, overall weight and aerodynamic efficiency”

I.e. the interactive integrated structured package package.

Chapman was likely to have decided what was required combined “common sense and scientific design”

Factors of Production and Resources / Momentum

What Chapman possessed and formed his considerable resources were: –

  • A formidable team of men and technological skills and particular the aeronautical craft skills of Mike Costin
  • The exceptional and sympathetic driving skills of Jim Clark
  • The experience and knowledge of the monocoque chassis of the Elite
  • The performance of the backbone chassis Elan
  • The “Wobbly web wheels”
  • Suitable plant and premises
  • Knowledge of aircraft technology and possible fuel bags e.g. FPT fuel bags
  • The strategist, holistic designer able to conceptually grasp the problem and interconnectivity

 The Team Chapman Assembled

Those included are believed to be: –

  • Alan Styman
  • Len Terry
  • Ian Jones
  • Mike Costin
  • Dick Scammell
  • Ted Woodley
  • Cedric Selzer
  • Jim Endruweit
  • David Lazenby
  • Bill Webb
  • Paul Wright
  • Mike Wardle
  • David Shuttle
  • Derek Wilde

 Past Precedent

The monocoque was not original.

The better reference works [see below] give historical details and applications. They include:  –

  • Hanley Page aircraft from 1911
  • Louis Bechereau  -streamlined fuselage load bearing stressed skin
  • Cornelian light car c 1915
  • Gabriel Voisin racing car 1923
  • Alec Issigonis and Laurie Bond’s   monocoque -750 Austin 7 single seat racing car
  • Tom Killeen monocoque sports car in mid 1950’s
  • Jaguar D type centre section
  • BRM P25 c 1955-57
  • Frank Costin design for Marcos sports racing car of late 1950’s early 1960’s constructed of laminated plywood.

These may be grasped with reference to editor’s photographs:

  • Fuselage of Horsa World War 2 glider
  • Sir A. Issigonis single seat racing car

Shell Shocked

Conventional wisdom suggests and inference is that Colin Chapman devised the monocoque chassis possibly in a flash of inspiration. The editors doubt this and do not believe it to be consistent with the Chapman methodology. The inspiration theory seems to ignore the scientific analysis of which Chapman was capable and indeed him not using very recent experience or his strategic deductions relating to the opposition and what could be extracted from the opportunity.

The editors believe that the type 25 was really an extraordinary synthesis by Chapman. He was able to feed into the equation the fixed parameters outlined Additionally his own products were an in-house resource. Its very probable that there were ongoing discussion and bouncing of ideas and that the monocoque germinated and was eventually conceived as an integrated totality and holistically by Chapman. However we ought note that the late Ron Hickman suggested an occasion when John Standen drawing experience from the backbone chassis of the Elan suggested that it might form the basis; which in deed it did.

 The term monococque can be slightly confusing and the editors suggest the following might be complementary for the purpose of mental imaging: –

  • Aluminum monococque with semi-stressed engine
  • Stressed skin chassis
  • Large diameter tubular backbone
  • Twin pontoon monocoque
  • Canoe
  • Bathtub
  • Two monocoque booms linked by an undertray

Bamsey observes: –

“Chapman had noted that the Coventry Climax V8 engine designed specifically for the new formula was capable of accepting chassis loads and he incorporated it and its fuel tanks into his new –style fuselage. Although called a monococque. This structure did not consist of an aircraft –style single shell. Instead Chapman set two torsion boxes either side of the power train and the driver, these boxes wide and deep enough to form rigid flanks for the fuselage while providing the required fuel accommodation. Bulkheads and the engine tied the two boxes firmly together while the engine and driver squeezed between them, the narrow cockpit closed by g.r.p. shroud””

Nye provides an excellent comprehendible description of the chassis concept: –

“The Lotus 25 “bath-tub” chassis structure was effectively two monococque booms linked by an under tray, a bulkhead between cockpit and engine bay, a dash-panel frame and forward bulkhead which provided font suspension mounts and included a hefty cross beam to tie the bottom wishbone mounts across the car”

He continues: –

“The Lotus monococque finally scaled a mere 65lbs bare, yet offered 1,000 lbs ft/degree stiffness, rising to 2,400 lb ft/degree when the Climax V8 was installed in the rear bay………The rear horns of the pontoons provided mounts to which the V8 engine was rigidly bolted contributing to chassis stiffness…”

The Type 25 essentially comprised the following: –

  • Front and rear bulkheads
  • Semi –stressed engine
  • Roll hoop
  • Dash hoop
  • Cockpit floor
  • Integral seatback and fire wall
  • Fuel containers

It’s reputed that the Type 25 took in the region of 200 man-hours to build.

The Type 25 is made more comprehendible by the technical drawings of James Allington.

Note some of these best drawings are published in Lotus 24,25,28,29, 33 by Unique [which its believed were taken from “Autocar”]

Chapman is often quoted as saying “It designed it self” the Type 25 might be one of his best examples where design actually dictates it self from the definitions of constraints and opportunities. The Chapman methodology was to not to be handicapped or constrained by conventional restrictions / limitations /regulation or received wisdoms

The monocoque structure was to determine the chassis in motor racing to he present day.


To fully comprehend the significance, commercial and competition advantage of a patent the following extracts are extremely useful: –

The Intellectual Property Office [Patents Office] defines a patent as: –

“A patent protects new inventions and covers how things work, what they do, how they do it, what they are made of and how they are made. If a patent application is granted, it gives the owner the ability to take a legal action under civil law to try to stop others from making, using, importing or selling the invention without permission. This may involve suing the alleged infringer through the courts, which is costly and time consuming because it involves expert legal advice. The patent owner needs to be able to pay for this civil legal action and advice themselves, although they may get some costs back if they win their case.”

Further advantages and uses are provided by Pipers Patent Attorneys: –

“The reasons for filing a patent application are as varied as are the reasons for the existence of the vast numbers of industries, businesses and products that populate our daily lives – but the main reason that dominates an applicant’s decision to file a patent (or any Industrial Property for that matter) is to maintain an advantage gained through brilliant innovation, small hard-earned incremental advances or even through good luck. 

Filing a patent application is all about maintaining and exploiting a market or a technological advantage. A patent allows its owner a legal means to prevent would be a competitor from gaining a foothold into a particular area of commercial endeavour that would not otherwise be possible. Patents can be used positively as a means to capture an area that needs to be developed, or they can be used negatively as a deterrent to unauthorised copiers. Either way they are a formidable commercial tool. Patents provide the platform for making important commercial decisions – they are all about how best to use limited capital resources for greatest impact. It has been said that Patents allow innovators to gain vital bridgeheads into technical areas, which can be exploited to:

Consolidate a Strong market position.

Provide new Revenue streams through the licensing or sale.

Gain investment funds to develop and market new products.

Increase in negotiating power through cross licenses or Joint Venture agreements.

Provide the basis for a company culture based on innovation, brand presence and design.

Provide a positive image to potential investors, customers, manufacturers and distributors

Attract and retain key personnel enabling new products to be developed further and

Secure overseas markets, distributors and alliances. 

Secret Success

We are reliably told that the Type 25 was designed and built with considerable secrecy at the Cheshunt factory. [This not unusual in such a high technology sport and continues to the present day. All major FI teams are concerned about security and Industrial espionage] Chapman application for a patent and its date is informative. Conventional wisdom suggests that Chapman had some reservations about the performance of the monocoque.

The editors believe that Chapman’s application for a patent was founded on some certainty of the success and that obtaining the patent [see separate paragraph] was to secure the commercial and competition exclusivity on his design. The editors consider that once built and stress tested Chapman knowing the weight and rigidity would have been well aware of the potential. His great unknown might have been the performance under racing conditions. [Aeronautical practice had its advantages but the Comet had demonstrated there could be unanticipated structural issues].

As a supreme strategist Chapman would have been aware the margin between the competitions was small and that his chassis design may have been the greatest variable guaranteeing success.

There might not have been time for extensive testing and this could have given the competition insights in advance and robbed his significant advantage.

In addition although the staff may have been sworn to secrecy there always remains a fear that secrets leak out. Again realizing the successful determining factor of the chassis Chapman may have felt he patent was a means to safeguard a preeminence that might last for several years. This success might guarantee that others were required to pay for the knowledge or product if they wished to remain competitive / compete. Otherwise racing rewards would be compensation.

Patent Reference

A copy of the Patent Specification and associated drawing for the Type 25 is published in Nye “The Autocourse History of the Grand Prix Car 1966-91”

The details are:

Reference No: L021561

Date of filing complete specification: September 6,1963

Application Date: June 6, 1962 No 21977/62

Complete specification published March 2 1966

Additionally the facts can be confirmed by reference to the Internet at the Intellectual Property Office.

Obtain information access by: –

  • On line patents service
  • Searching the EPO Espacement service
  • Advanced search screen
  • Applicant: Anthony Colin Bruce Chapman

References are:

Page Bookmark”GB1021561 [A]-vehicles

Abstract of: GB1021561

No.: 21977/62

Bibliographic data: GB1021561 [A] -1966-03-02

International Grand Prix Competition 1963

The following machines and drivers were contracted for the 1963 season: –

Marque Driver
B.R.M G.Hill R.Ginther L.Bandini
Cooper Climax B.McLaren A.Maggs J.Bonnier
Ferrari J.Surtees L.Scarfiotti
Lotus Climax J.Clark T.Taylor
Lotus B.R.M J.Siffert J.Hall
Brabham Climax J.Brabham D.Gurney
BRP B.R.M InnesIreland
Porsche Beau’ G.Mitter

“The Whole is Greater……….”

The landmark designs of Chapman which we have noted shared an intensity or concentration of the technological content integrated with practicality and fitness for purpose.

With the Type 25 he achieved: –

  • Some consistency of reliability after development
  • Low weight
  • Minimal frontal area / low drag
  • Stiff chassis contributing to softer suspension; working with the tyres for optimized road holding
  • A driver whose abilities and style harmonized with the machine he was given

This in reality Chapman held superiority in strategy and tactics and that any Achilles heel was being minimized. The thoroughness and attention to detail is evidenced in the results.

Many informed observers comment that such was the ability of Clark that he might have won anyway.

In the history of motor acing the editors feel that there is rare example of such total synergy.

The confirmation of the dominant combination is evidenced by the World Drivers Championship and Constructors Cup 1963 results:

GP Driver Position Machine
Monaco J.Clark Retired Lotus Climax Type 25
French J.Clark 1st Lotus Climax Type 25
Italian J.Clark 1st Lotus Climax Type 25
Belgium J.Clark 1st Lotus Climax Type 25
British J.Clark 1st Lotus Climax Type 25
USA J.Clark 3rd Lotus Climax Type 25
Dutch J.Clark 1st Lotus Climax Type 25
German J.Clark 2nd Lotus Climax Type 25
Mexican J.Clark 1st Lotus Climax Type 25
S.African J.Clark 1st Lotus Climax Type 25


Colin Chapman commented but was not always quite so modest! : –

“Quite the cleanest nicest –looking car we’d ever made. There were no holes in the bodywork, the engine and gearbox were beautifully cowled- in and it worked very well……..”

The Proposed CCM&EC

The proposed museum believes that commercial considerations are both necessary and complementary with its educational objectives.

For these reasons our Business Plan includes provision for promoting products and services which share Chapman’s ideals of mechanical efficiency and sustainability. In addition we propose merchandising that explain and interprets the social and cultural context of Chapman’s designs in period. Its suggested there will be catalogue for on line purchasing.

In particular the proposed CCM&EC ought have well-established links with the Patent Office/IPO in order that students can study and benefit from ideas and relate these through exhibits to actuality. In the process critically establishing their importance, application and potentially sparking improvement. By studying Chapman/ Lotus and others many complexities can be unraveled and indeed sources of inspiration /ownership better attributed.


This article is considered important for its discussion about the commercial exploitation of design and problem solving in relation to patents. It’s acknowledged that patents are not perfect and more recent inventors like Dyson have experienced problems. However the engineer and entrepreneur must be aware of their existence. There is the possibility of both protecting and exploiting ones own originality but there can be occasions when it might be economic to use others providing just payment is concluded.

A frequent examination of patents is a powerful source of inspiration and has a ratchet effect of driving forward innovation.

Nor should it be overlooked that patents are linked to innovation and may under the correct circumstances help produce a more sustainable economy through the elimination of waste both in materials and production.

The editors conclude that Colin Chapman as a patent holder signifies his status as an Industrial Designer / entrepreneur and that this fact cannot be diminished.

If its considered desirable to base national wealth on innovation design and technology then it would seem incumbent to allow the proposed CCM&EC to lead the way. It will not be found lacking in ideas or inspiration


Lotus 25.Climax FWMV- a Technical Appraisal .Ian Bamsey.Haynes.1990.


Motor Racing –The Records.I.Morrison.Guild.1987

Famous Racing Cars. Doug Nye.Guild.1989

Theme Lotus. Doug Nye.MRP.1986.


Lotus: Books

ISBN: 1841553786

Autocourse History of the Grand Prix Car.1966-91. Doug Nye.Hazelton.1992.


UK – Intellectual Property Office []

Pipers Patent Attorneys:

Great quote..Was he aware of Lotus 25 as a vision!!

Its by Antoine de Saint-Exupery who was French aristocrat , poet, writer and pioneer aviator and member of Free French resistance. In his lyrical work “ Wind ,Sand and Stars”, he states:

“a designer knows he has achieved perfection not when there is nothing left to add but when there is nothing left to take away”