The C5 conceived

Clive Sinclair recalls that it was as a teenager with a holiday job at the electronics instrument company Solatron that he first started to enquire into electric vehicles. They would be silent and pollution-free, and he was fascinated with that possibility. However, the received wisdom was that electric vehicles were slow and cumbersome (because of all those batteries) - not to mention unreliable.  

    Sketches by Denis Roberts

Early motor cars had generally emerged as an existing design of horse-drawn vehicle fitted with an internal combustion engine - and were they not called "horseless carriages"? Electric vehicle design was going the same way; now the internal combustion engine chassis was being used as a base, fitted with batteries and an electric motor. Sinclair thought that the proper approach must be to start from scratch (what we now call ground-up design - nothing to do with pulverising) rather than to tinker with an existing model (top-down design).

Sinclair pondered long on the personal electric vehicle, and in the early 1970s he had Chris Curry working on the problem at St Ives Mill. At that time, he thought that it was the motor wherein the secret lay, and they worked on a wafer-thin model which was mounted on a scooter; if you stood on the platform with one foot, and pushed yourself off with the other as you pressed a button on the handlebars you could glide up and down the lab. However, it was at about this time that the pocket calculator became all-consuming, and although Sinclair continued to talk about electric vehicles, he sponsored no further work on them until the end of the 1970s.  

    Tony Wood Rogers on prototype chassis

In the 1970s, as the world became more conscious of the problems of pollution and the need to conserve energy, governments - and government bodies such as the Electricity Council in Britain - made funds available for sponsoring development work on electric vehicles. Some 5.5M was contributed in the decade, notably 2.3M to Lucas for the Lucas/Vauxhall delivery van, 1.9M to Chloride Silent Power for the sodium/sulphur battery and 0.5M to Lucas again for the nickel/zinc battery.

With the interest shown by the government in electric vehicle research, it is not surprising that all those manufacturers who had been working on electric vehicles, Lucas prominent among them, found a sympathetic ear for their parliamentary lobbying; a working party was set up and eventually the electrically-assisted pedal cycle legislation was passed in August 1983. By that time, the companies in the automotive industry who had been pressing for the new laws had all felt a change for the worse in the industrial climate and were hardly in a position to pursue the topic.

It was about Christmas 1979 that Sinclair approached Tony Wood Rogers, with whom he had kept in touch since he had worked at Sinclair Radionics in the early 1970s. Rogers preferred to live in the West Country, and was now running the Exeter Academy. Sinclair asked him if he would like to act as a consultant on the electric vehicle project, and briefed him to "perform and present a preliminary investigation into a personal electric vehicle. The vehicle is assumed to carry one person (with a possible second small person only by squeezing), and is seen as a replacement for a moped and limited to urban use with a top speed of 30 mph."

They expected to launch the vehicle early in 1984, and were even then thinking in terms of 100,000 vehicles manufactured annually. A vehicle to this specification later became known as the C1. At the time, this was seen as the only way to get into the electric vehicle field; later, when Rogers tuned in to the new legislation, the specification changed to what we now know as the C5 (C for Clive and 5 for five).

Together, Sinclair and Rogers examined different vehicle layouts, and Rogers built prototypes to prove principles rather than to develop a product. During 1980, the specification of the vehicle became clearer. It was to carry the housewife, the urban commuter or the youngster; its advantages over the moped would be that it offered greater safety, weather protection, economy - and style - at a competitive target price of 500, based on the likely cost of such a vehicle vis--vis the competition: the moped and the second car. It would be designed to be easy to drive, easy to park, easy to get into and out of, and easy to load. It would need minimum maintenance and would provide maximum power efficiency for minimum battery size. For urban performance, it should have a minimum range of 30 miles on a fully charged battery, which could be extended by means of an additional battery. Batteries would last for two years. It would be designed and engineered for simple, high-volume assembly using injection-moulded plastic components where possible and a polypropylene body.  

 Iain Sinclair with prototypes

On 26 March 1980, the Government abolished motor tax for electric vehicles. Department of Transport figures for 1978 showed that there were 17.6M licensed vehicles in the UK, including 14M cars and 1.2M mopeds and motorcycles. 2.4M households had a second car.

There were 175,000 electric vehicles in use, of which 45,000 were road-going: 90 per cent of them milk floats. Then the very telling information - 93 per cent of all cars travel less than 60 miles per day; the average daily distance per car is 13 miles; virtually all journeys by pedal cycle and moped are less than six miles.

The Transport and Road Research Laboratory (TRRL) gave comparative figures for primary energy consumption of vehicles in the following ratios - lead-acid electric vehicle (111): petrol car (100): diesel vehicle (55). However, continued the report, for urban driving the electric vehicle is twice as efficient as the petrol car, and better electric vehicles and batteries will further improve its efficiency.

There were clear advantages for electric vehicles. During the day they would provide an environmentally acceptable method of transport, and when the batteries were being charged (normally during the night) they would be using off-peak power. We have already seen that the British government sponsored 5.5M of electric vehicle research in the ten-year period ending in 1983; by contrast the US government allocated 71.5M for the ten-year period ending in 1986. Although there was a great deal of interest in promoting electric vehicles, the submissions to the government committees concentrated on public and commercial transport and made no mention of personal transport.

By March 1982 the first Sinclair vehicle, the C1, had reached quite an advanced stage. Innumerable calculations had been carried out on power efficiency, and the engineering of the battery motor and drive was largely complete. Tony Wood Rogers had built and tested a number of chassis, the later ones using components from preferred suppliers. One of the fundamental factors which had been realised from an early stage was the need to reduce drag on the body as much as possible.

It is a widely believed fallacy in the motor industry that below 20mph wind resistance doesn't matter. The truth is that wind resistance matters hugely, as any cyclist will tell you. It just seems to matter less with a car because there is so much rolling resistance at low speeds, but it is none the less significant if you are trying to conserve energy. If the rolling resistance of a motor car were as low as that of a bicycle, manufacturers would soon be putting their body shells into wind tunnels to study the effects of low-speed drag.  

    An early embodiment

The body shape and basic layout of the C1 body was tested in the wind tunnel at Exeter University; Rogers made full-size fibre-glass shells and fitted them to working chassis. He also surveyed all the regulations that might affect electric vehicles, paying particular attention to safety. Part of the ground-up approach was not to spend - as other investigators had done - enormous amounts trying to develop a more efficient battery, but to make use of the models already available. Sinclair's very sound reasoning was that a successful electric vehicle would provide the necessary push to battery manufacturers to pursue their own developments in the fullness of time; for him to sponsor this work would be misplacement of funds. There was, however, a need for a battery which would stand up well to the continuous charge-discharge cycle, and this he was obviously prepared to investigate.

So far, all this development work had been carried out under the umbrella of Sinclair Research Ltd, but when the project seemed to have a future, Sinclair saw that the cost of failure would be comparable with the reward of success. Moreover, he saw that it would need a very large sum to develop the vehicle, to tool up for production, and to launch it. He therefore decided to sell some of his shares in Sinclair Research in order to raise capital to invest in the electric vehicle programme as a separate company - Sinclair Vehicles Ltd. The deal - described in Chapter 12 - was completed in March 1983, leaving him the richer by 12M.

Sinclair and Rogers now decided that the most important thing to do next was to have the vehicle body professionally styled, and the project was handed over to Ogle Design in Letchworth, well known in the motor industry. For about a year, Ogle worked on the project considering not only the styling but also the production engineering. But although their methods of working were admirably suited to the car industry, they were not used to working with the likes of Clive Sinclair and Tony Wood Rogers. They spent a lot of time and money on aerodynamic tests, where Sinclair and Rogers preferred the quick estimate first and a detailed analysis later if it seemed to be profitable. Ogle did not appreciate that they were designing a personal electric vehicle rather than a car, and instead of building on the cycle technology and looking at ways of reducing the rolling resistance, they veered towards car design and increased the weight from less than 100kg to over 150kg. Sinclair and Rogers became increasingly worried.

Sinclair's search for someone to run Sinclair Vehicles finally led to his meeting Barrie Wills. Wills had taken part in building a factory for Leyland National in the late 1960s to manufacture the first bus to be built on car-assembly principles. He joined Reliant in 1972 when that company was at a crossroads investing a lot of money in a new product, again an almost greenfield project. He was De Lorlean's longest serving employee and is saddened that the De Lorean will go down in history as a failure, when it was so nearly a phenomenal success.

In October 1982, a mutual friend asked Wills if he was interested in meeting Clive Sinclair to talk about his electric vehicle enterprise. He replied that of course he would like to meet Clive Sinclair, but that he was not in the slightest bit interested in electric cars; one thing that 25 years in the motor industry had taught him - he thought - was that there was never going to be an electric car. But when he met Sinclair and found he was doing something entirely original, based on sound principles and the ground-up approach, he was immediately won over. This was the time that the crossroads had been reached with Ogle Design, and Wills took part in assessing their work. He had always believed - and Sinclair didn't need persuading - that there was little future in any personal electric vehicle which could not compete with the price of a second hand car. It was lack of appreciation of this, he thought, that had so far bedevilled electric vehicle development.  

    The chassis clothed

By the time Wills joined Sinclair in March 1983, they had decided to put the Ogle programme on ice; it was somewhat ironic that the new managing director of Sinclair Vehicles should have been party to a decision which meant that he had joined the company without a product. But there was another factor which made the decision to freeze the Ogle work less painful. Sinclair and Rogers had now become aware of the impending legislation which would introduce a new category of vehicle - the electrically assisted pedal cycle. They saw that everything which had prevented the electric moped from competing with the conventional moped (the road tax, the insurance, the helmet, the driving licence) would be eradicated at a stroke: the only less-favourable aspect was the reduction of maximum legal speed to 15mph.

The closer they looked at the draft legislation, the more apparent it became that a tremendous amount of the development work that they had already done could be applied to a new vehicle: unique, exciting, attractive, stylish - and, they thought, marketable. They took as the basis of their new design the recumbent cycle with two wheels at the rear for stability, and thus was the C5 born.

Legislation had given Sinclair's electric vehicle development a new impetus; he could now see the C5 as his first shot at opening - once again - a market that did not exist. He would use the C5 to attune people to the idea of electric vehicles - to prove that they were a viable proposition - so that he could carry on "to the end of the century and beyond" introducing more and more advanced models.

The new legislation had been written so that vehicle designers would have as much freedom as possible; notwithstanding this, the design that Sinclair Vehicles produced was a complete surprise to the Department of Transport. The regulations to be met by law are fairly short and simple. The cycle - as it's called technically - has to weigh no more than 60kg including the battery; as it was, the design of the C5 was so honed that it was possible to fit two batteries without exceeding the 60kg weight limit. The motor must not be rated at more than 250W. The vehicle has to meet British Standard regulations for cycle braking. It has to have an on/off switch biased towards off, it has to have a plate stating who the manufacturer is, and it has to be "electrically assisted", so it must have pedals. It can be ridden (driven) by anyone over the age of 14, with no licence, no insurance, and no crash helmet.

It was about this time that Sinclair was looking very closely at Lotus cars, assisted by Wills who had known the company for 15 years or so. For some time, they talked of the possibility of Sinclair buying into Lotus, but he eventually decided that it was not going to be the best way forward either for Lotus or for Sinclair Vehicles and the project was abandoned. But when Wills had been at Reliant he had developed a good relationship with Lotus; he and Sinclair therefore decided to place a development contract with Lotus to take the basic C5 design, finish the detailing, build the prototype and the test rigs, develop the vehicle, devise and execute the test programmes, and generally assist the project from its design and development stages into production.

Brian Spooner was the product manager at Lotus. Initially, he was sceptical about the whole project; even seeing the model left him somewhat cold. However, when he got into it, and drove it for the first time he began to warm to it, and once he started to look at the engineering he became excited about it very quickly.

This was the common pattern all the way through the project. Although the development work was kept extremely secret - and the fact that Lotus was involved never seemed to have leaked out until the launch of the C5 - a number of sub-contractors and suppliers had to be shown the vehicle. And their reaction to it almost always followed the same course: first disinterest, then scepticism, and then - after a ride on a prototype - wild enthusiasm.

Lotus's first task was to examine the model and produce a package of proposals of what they would do. Down in Exeter, Rogers was doing some more work in the wind tunnel and further reduced the drag factor from 0.95 to 0.6. Throughout the project, the relative positions of the seat, pedals and steering remained much the same; however, to avoid the need for an adjustable design - which would mean extra cost - they worked on a layout which would allow a range of people from a relatively slight 14 year old girl to a notably tall man to sit in the machine and pedal it in comfort. This work was completed in 1983 and Lotus then went on to detail design, development, and testing of the vehicle. A great deal - perhaps a quarter - of the work went into examining the legal and safety aspects; Lotus took all the British standards that apply to cycles, and where they applied to the C5 ensured that it behaved as well as, if not better than, the stated requirements.

The C5 met the Ministry of Transport regulations in every way. The regulations were, of course, aimed at encouraging manufacturers to produce an electric vehicle, perhaps an unusually far-sighted approach. Those from the Ministry responsible for drafting the regulations went to look at the C5. They were incredibly impressed, but though they admitted that it wasn't quite what they had imagined, they were delighted and full of praise for both the vehicle and the team.

As the project progressed, further body designs were tested in the wind tunnel and full-size fibre glass shells were built. A number of people looked at the styling and, although they were not happy about it, could not pinpoint exactly what ought to be done.

It was at about this time that Sinclair Research took on  Gus Desbarats, an engineer with a postgraduate training in industrial design. It was he who took a completely new look at the project; within a week or so he produced a revised styling on which the production C5 body was based. After a new clay model had been built, refinements such as the wheel trims and the luggage compartment were added, and there was the finished body, more or less as it went into production.

In parallel with this was the mechanical design, crucial to which was the chassis. Again the layout dictated the shape to some extent and the chassis emerged as two identical metal pressings, joined top and bottom with a closing plate at the rear. The design was subjected to a thorough stress analysis in order to produce a light structure which would have enough torsional flex to provide a suspension for the vehicle - there had never been any thought of a separate suspension system.

Tony Wood Rogers had been working on battery development, when out of the blue came a letter from one Joe Caine, an ex-Chloride man who wrote to Sinclair saying that he'd heard about the electric vehicle project, that he knew that the secret was to find a really good battery, and that he (Caine) knew all about batteries, and would like to help. Rogers went to meet Caine, took him on, and together they toured all the battery manufacturers to appraise the joys and woes of battery production. Soon, Caine was set up in a lab in Bolton with 10,000 worth of automatic battery testing machine, and in conjunction with Oldham developed a battery for the C5 whose life exceeded the 300 charge-discharge cycles specified. Rogers had also found a suitable motor - from Bosch - designed primarily to drive a truck cooling fan, which delivered the maximum 250W output. It was left to Lotus to design a gearbox for the C5 final drive.

The body of the C5 was made from two injection-moulded polypropylene shells; the upper shell being one of the largest - if not the largest - injection moulding of its type in the UK: possibly even in the world. The two parts were to be bonded by placing a tape around the joint which can be heated with an electric current. They would be aligned on a jig and pressed together, the current passed, and - hey, presto! -a body shell. The process is used for manufacturing the Topper dinghy and the BL Maestro front and rear bumper assemblies. J.J. Harvey in Manchester - one of the UK's leading mould-makers - made the moulds, and Linpac, the UK's largest thermoplastic moulding company, supplied the shells. ICI, who supplied the raw material, took great interest in the project, and ran computer programmes relating to mould flow. It was very much a team effort: a tremendous amount of know-how went into the development and manufacture of the C5 body after its shape had been determined. One mould set would produce up to 4000 parts per week.

The original rear axle design was a tube with two stub axles welded to it; when Lotus examined it from a production engineering point of view they saw that they could draw on car steering column practice; the rear axle thus became a tube swaged down at each end with rolled threads and splines - a very low cost, handsome, elegant single piece component.

Perran Newman of MetaLab, working at "arm's length", developed the circuitry which indicates, via green, amber and red LEDs, the state of the battery charge. As each segment is extinguished, you know that your battery is getting lower; at the last light, you know you have 10 minutes of driving time left and then it will start flashing; if you don't switch off it will switch itself off and you will have pedal power only. In the advanced model, another display acts as an ammeter with two green segments, an amber, and two red; red for when you're pulling a high current, showing that you really ought to be pedal-assisting the motor. The idea is to try to keep the display green - the most economical running mode.

The vehicle has three systems for protecting the motor. The first is a stall system; if you draw too much current for too long (so that the motor heats up) the electronics will switch off and force you to wait half an hour before you can switch on again. The second system is a thermistor probe in the end of the motor armature which cuts off the current if the temperature rises above a certain level; it will reconnect when the temperature drops again. The third system, if the others fail, is a thermal trip built into the motor. The motor is therefore super-protected against all forms of idiocy.

The fact that Sinclair bought an option on the De Lorean assets in Northern Ireland led to some confusion in the press. Sinclair Vehicles had been set up to develop a range of models over a period of time, starting with the C5 as the most basic and leading on to others which would become more and more car-like. Now, one of the attractions of the De Lorean plant was that it had one of the most well-developed automated plastic body manufacturing facilities in Europe, or even in the world. This facility could have been of use in possible Sinclair Vehicles developments; the option was on some of the assets within the factory - indeed, Sinclair Vehicles would not have to use the factory at all; it could buy the assets and move them elsewhere if it wished. Talks lasted for about a year, but there was mounting pressure from the receiver wanting does to dispose of De Lorean's assets and, so Sinclair relinquished the option and the plant went to auction.  

Barrie Wills testing to destruction

From the very start of the project, Wills's approach had been to document everything so that the reason for every decision was on file. On a cycle, the law calls for lights or a reflector - the C5 incorporates both; it has the normal lighting system built-in, with an additional reflector which forms the top half of the lamp. There is reflective tape around the body and on the wheels. The rear light incorporates a central rear lamp and reflectors. The kit as originally planned included a reflector pole to increase the height of the vehicle by two feet with a white reflector at the front and a red one at the rear - the decision to make increased visibility an extra would be one of the pieces in the jigsaw of the C5's disappointment. The vehicle was put through an extremely rigorous test schedule - the chain, the pedals, the effect of impact.

It would have been extremely adverse publicity if a fatal accident were to occur through the C5 not having been properly tested. Anyone who might conceivably have been concerned with safety was consulted, and Sinclair Vehicles "took full note of all the recommendations which might improve the safety of the vehicle."

At the beginning of Barry Wills's association with Sinclair Vehicles, he was living in the Midlands while the company was based in Motcombe Street. He did not particularly want to move house, and in any case London is hardly the place to set up an automotive company - even a fringe automotive company. There was therefore a strong case for locating the business in the Midlands where there are likeminded people, the resources of the industry, the Motor Industry Research Association (MIRA), and a geographical centre of the motorways. There was no shortage of empty offices and factories in the West Midlands, mute testimony to the contraction of the automotive, machine tool, and aircraft industries. But a radically new product needs radically new thinking; where can you find space which can be expanded as you want it, so that you do not have to think too far ahead? How about a Science Park? Warwick seemed to be the most progressive with historical links to the motor industry, and it was on that science park - with all its flexibility - that Sinclair Vehicles' head office was established in 1984.

Rodney A M Dale 1985. Reproduced by kind permission of the author.
Visit Rodney Dale's website at:

[On to the next chapter]

[Back to "The Sinclair Story" index]