Design Thinking

by Nigel Cross

  ‘So I rushed around and looked at the technology of micro-filters, mainly in the medical industry … they were using these organic micro-filters which let the fluid through themselves but very, very, very, slowly. And we built the world’s tiniest throttle valve with one of these filters in it, and a tiny little pin – we were using drills that you couldn’t even see! We went and quickly developed what size hole we needed, so that it took a lap to push the fluid through these little holes – all naturally with the downforce – pushed the fluid into the reservoirs and the car was stuck on the ground, running with its skirts virtually touching the ground. And because it took so long for the fluid to get back through the same valves and filters, it held the car down there, and after the race you have the slowing down lap … and the car just slowly came back up. Nothing to do with the driver at all, just physical forces! And we went to the first race in Argentina and just blew everybody into the weeds, just totally; and everybody went bananas!’

  Other teams protested that the Brabham cars must have been fitted with a driver-operated device. It was obvious that the cars were lower during racing than they were in the pits, but of course the scrutineers could find no illegal device. Under pressure from the other teams, the authorities pointed out that the Brabham cars were clearly lower than 6cm when out on the circuit, which contravened the regulations, but Gordon countered that, at various points so was every other car. To stop the protests, he suggested to the authorities that every car should have its underbody painted, and at the end of the race every car which showed that at some point the underbody had rubbed the ground should be disqualified; and of course the other teams would not accept this.

  To confuse the competition even further, Gordon Murray left the small hydraulic valve units in full view, but put a large dummy aluminium box with wires leading into the gearbox on one of the underwings of the car. ‘All the teams without exception came along and tried to get the mechanics drunk and things, to try to find out what was in the box – nobody noticed the valves, and there was nothing in the box!’ For some time the other teams experimented haphazardly with varieties of hydro-pneumatic suspension systems, to Gordon’s amusement, but, very frustratingly for him, just a few races later in the season, FISA reversed its stance and allowed driver-operated switches for controlling suspension height.

  The hydro-pneumatic suspension system was an example of an innovation initiated by a change in regulations which forced Gordon Murray’s thinking onto how to retain the ground-effect advantage. It is an example of radical design innovation, through thinking from ‘first principles’ about the effects of natural forces, and having the motivation to follow through a basic idea into finely-detailed implementation.

  Pit Stops

  Another example of radical innovation by Gordon Murray was the Brabham team’s introduction of planned pit stops for refuelling during a race, before this became normal practice and was eventually ruled out in the regulations for the 2010 season. This was not so much an innovation in the car design per se, but reflects more of a systems approach to the overall goal of winning each race. At that time it was not normal to have pit stops as regular, planned parts of the race routine. Pit stops were for emergencies such as changing a punctured or badly worn tyre. For Gordon Murray, the innovation of introducing planned pit stops was part of an overall strategy arising from taking his thinking back to a basic issue – how to make the car lighter. The lighter the car, the faster it is in accelerating and decelerating.

  Gordon says his mind was ‘banging away’ at this issue for a long time. He went to the regulations and realised that there was nothing in them about when you could put fuel into the car. So the idea dawned of running the car with only a little over half the normal, full-race fuel load, and including a pit stop for refuelling. But that was only the starting-point for a thorough investigation of the implications of such an idea, and of a working-through of the detailed implementation.

  The first thing to do was to evaluate the implications of the idea. A pit stop takes a lot of time; not only is there the actual stopped time of the car at the pits, there is the time lost in decelerating and driving into the pits and also in accelerating away again on tyres that take a couple of laps to heat up to optimum operating temperature. Formula One pit stops eventually became refined down to an incredibly quick norm of about six seconds actual stopped time, in which time all four wheels were changed and maybe 100 litres of fuel taken on. The total racing time lost was perhaps some twenty seconds. Gordon calculated that if the total racing time lost by a pit stop was less than twenty-six seconds, there could be sufficient advantage gained elsewhere to make it worthwhile.

  There were many factors that came into calculating the advantage. As well as the weight reduction, half-size fuel tanks also have an advantage over full-size ones in that the weight distribution is lower, and is more constant throughout the race, and the roll-couple on corners is lower, allowing faster cornering. Tyre wear, and the complicated choices of harder or softer tyre compound, also becomes a critical factor, because a lighter car can run on softer compounds which also improve cornering speeds. Even the psychology of racing came into it, because a car with obvious advantages in the early part of a race could lead other competing drivers into pushing their cars harder, or into taking more risks. For all of the objective, measurable factors, fine calculations were made, leading to the conclusion that a pit stop had to lose less than twenty-six seconds racing time to be worthwhile.

  At that time, a quick pit stop for tyre changes took about fifteen seconds of actual stopped time. Gordon Murray calculated that he had to get this down to about ten seconds and to reduce as much as possible the slowing-down and warming-up times. And so, ‘the innovation process continues, because you’ve got all these new things that nobody’s done before that you have to come up with’. An extraordinary development programme had to be undertaken in an incredibly short time.

  ‘From having the first idea to having a pit-stop car running and doing a test was three or four weeks, and that’s all the time that you have. So you would take each individual thing and tackle it. Say, OK, how can we get thirty-five gallons into the car in ten seconds? The only way you’re ever going to do it is using pressure, and then you have a crash programme to develop a system … That’s what is great about race car design, because even though you’ve had the big idea – the “light bulb” thing, which is fun – the real fun is actually taking these individual things, that nobody’s ever done before, and in no time at all try and think of a way of designing them. And not only think of a way of doing them, but drawing the bits, having them made and testing them.’

  Within three weeks, they had thought of, designed, made and tested a pressure-fed refuelling system. To improve pit-stop procedures, Gordon hired a film crew to film the team practising pit stops, and then played back the film, stopping it to identify difficulties and errors, and devising ways to improve the procedures. Such improvements included details such as re-designing the wheel-nut gun to improve its engagement with the nut. The new systems, the improvements, and the training of the pit team got the actual stopped-time down to under the target of ten seconds. One ‘big killer’ remained: ‘When you put new tyres on they were cold, and it always took two laps to get back up to speed, and the time you lost in those two laps killed the whole thing. So then I thought, well I know the tyres start working at seventy degrees centigrade … so we designed an oven, a wooden oven with a gas-fired heater, and we heated the tyres up, and ten seconds before the car was coming in we opened the oven door, whipped the tyres out, put them on, and the guy was instantly quick. Now every Grand Prix team has tyre heating; that’s where it started.’

  The example of the introduction of the ‘pit-stop car’ illustrates how a radical innovation was driven by the competitive urge to find a significant advantage within the constraints of the regulations; how the basic creative idea had to be evaluated on precise calculations; how a total systems approach was adopted; and
how implementation had to be carried through to fine levels of detail.

  F1 Steering Column

  The McLaren F1 sports car was designed on Formula One principles, and included many radical innovations. One of these was the interior seating layout, with the driver seated centrally and two passenger seats positioned slightly rearward and overlapping with the driver’s seat. This ‘arrowhead’ layout was something that Gordon had had in mind for many years, as evidenced by a sketch in his student notebook, some twenty-five years earlier! It is a very visible example of how he is prepared always to think anew about any aspect of the car that he is designing.

  As a less-visible example of his approach to designing from first principles, Gordon refers to a small and perhaps seemingly insignificant part of the McLaren F1, the steering column. ‘Conventionally, it would have been, right, steering columns are typically three-quarter-inch solid steel bars.’ He explained how this conventional solution arises because the column not only has to carry torsional forces from the resistance to the turning wheels but also bending loads from the driver leaning on it while getting in and out of the car. It also has conventional points of support, is mounted in rubber bushes to reduce noise, and it ends up being encased in a plastic housing for reasons of appearance and convenience. But it does not provide the sort of direct steering feel that a racing driver needs, and the McLaren F1 is supposed to be a driver’s car.

  So Gordon decided to apply racing design principles, starting by separating the needs to carry both torque and bending loads. Whatever the form of the steering column itself, it still needs a cover to house electrical cables and to mount switches, ‘so if you’ve got to have that anyway, why not use the insect principle where the skeleton’s on the outside, and make that the structure that takes all the bending forces?’ This thinking led to the design of the steering column itself as an aluminium tube of just 1mm wall thickness; ‘it’s only taking torque and it weighs nothing’. The steering rack is cast integrally with the bulkhead, so that there can be no relative movement. The support bush is right behind the steering wheel rather than down at the dashboard, and the system is now lighter but stronger than a conventional solution, and also has the right racing feel (Figure 2.3). The design process stemmed from considering first principles – separating the torque and bending loads – and from an imaginative breakthrough – using the housing cover for structural purposes as well as appearance and practicality.

  Gordon Murray insists on keeping experience ‘at the back of your mind, not the front’ and to work from first principles when designing. For instance, in designing a component such as a suspension wishbone, he says, ‘It’s all too easy, and the longer you’re in design the easier it is to say, I know all about wishbones, this is how it’s going to look because that’s what wishbones look like.’ But if you want to make a step forward, if you’re looking for ways of making it much better and much lighter, then you have to go right back to engineering analysis. He says it is like always designing things as though for the first time, rather than the n-th time.

  2.3 Gordon Murray’s explanatory sketch of the F1 steering column design. top: the F1, with an ‘exo-skeleton’ structural external casing to house cables and hold switches, and a rigidly-mounted small, light steering column; Bottom: a conventional design, with a heavy, solid column inside a light casing.

  City Car Design

  Gordon Murray is known principally as a racing car designer. But for many years he nursed a very different concept of what a car could be – a small, cheap, city-car. After he left McLaren he began development of this very different kind of car in his own design company. The resulting concept was finally announced in 2008 as the T.25 city car, and the first prototype was built in 2010. The T.25 is a very practical urban-use vehicle that can carry a driver with two passengers or a large amount of luggage or shopping; it is light and agile, with good performance and low fuel consumption, and occupies one-third of the road or parking space of a conventional car. However, Gordon Murray’s motivation for designing the T.25 was not so much the economic and environmental advantages it might offer, but a desire to design an efficient, small car that would be attractive and fun to drive, and would radically impact traffic problems such as congestion. His aim was to develop not just a new type of car but a new concept of personal transport.

  Just as in his racing car design work, the city car is also designed from first principles. This is clear in some of Gordon’s earliest sketches for the car (Figure 2.4), dating from the early 1990s, in which he pays special attention to the suspension system. The suspension system is an important feature in early considerations because a tall, narrow car such as the T.25 tends to roll sideways on corners, and that has to be countered in the suspension system. He also explained that, for economy, ‘I want to make a suspension with the least number of components and moving parts; this has only three parts in the whole suspension system.’ The same kind of thinking applied also, for example, to the initial ‘frog eye’ headlight design. ‘It’s not just styling, it’s a practical point of view, because I only want to have one sub-wiring loop for cost, so I want to put the [rear-view] mirror in the back of the light, so you have headlamp, parking lamp, main beam, low beam, indicators, side repeater, heating element, adjusting element for the mirror, and the mirror, on one sub-loop with one plastic plug, so you have one moulded pod that does all those things, all those functions.’

  2.4 Some of gordon Murray’s early sketches for the city car concept: (a) overall concept, (b) a very early sketch of suspension and other details, made in a pocket notebook, around the same time as the concept sketches.

  In fact, for this city car the innovative manufacturing concept is as important as the innovative design concept. This integrated thinking is essential to his approach to designing a low-cost solution, as he explains: ‘You need something that is small, light, radical, efficient, and it has to be cheap, because one thing you can’t do is build the world’s most sophisticated little city car that will save the world and then say to people it costs £17,000, because you won’t sell many – if you don’t sell enough it won’t make a difference, and the way you reduce the cost of producing a car and therefore the retail price is by first of all reducing the part count, the number of parts that go into the car, and that you do by design and by conceptual design.’ So for Gordon Murray conceptual design, detail design and manufacturing are all tightly bound together.

  2.5 Later sketches for the T.25 city car.

  Even a radical concept such as the easy-access, single, lift-up opening canopy, rather than side doors, came from the same approach. ‘Going from seven openings to five makes a car a lot cheaper and more rigid and lighter; going from five to three and from three to two is magic, and going down to one you can’t get any better – you’ve got to get into the car. So that sort of stuff you think about from the beginning, and that applies to lights, mirrors, instruments, wheels, brakes, everything.’

  After producing many dozens of small sketches of details and concepts over several years (Figure 2.5), and experimenting with performance, using different engines in some existing small cars, the design work took a major step forward when Gordon and his team built a very simple, full-size mock-up of the car, using wire and cardboard (Figure 2.6). The final version of the city car (Figure 2.7) bore a striking resemblance to that simple mock-up. The mock-up became a useful design tool, as it began to suggest some new possibilities. For example, Gordon’s earlier idea for the seating arrangement was for two people sitting in tandem, the passenger behind the driver. But when the mock-up was built, ‘we discovered that you could, quite easily with the same width of motor car, for short journeys, you could take three people in it’, using a similar seating layout as in the McLaren F1. Another cost-saving idea also arose from exploring the mock-up, when one of the team realised that the rear-located engine could be accessed from inside the car, so avoiding the need for an external access. Gordon explained that, ‘At one stage, we were looking
at having to have a boot lid to access the engine, until one of the guys said, Come and look at this, if you stand in the car you can open what is effectively your boot floor from the inside of the car, you can get to the oil and water and stuff from there – if you fold the seats flat, open the hatch in the floor and you are there.’

  In the city car design we can see that the same kind of design thinking is applied by Gordon Murray as in his racing car design. There is a fine attention to detail, that interlocks with the overall concept and can trigger some of the big ideas as well as the little ones. And there is a breadth of approach towards an overall goal that is greater than the apparent focus of attention, the car itself.

  2.6 The early wire and card mock-up for the city car, showing the single opening canopy.

  2.7 The first prototype version of the T.25 city car.

  Learning from Failures

  For Gordon Murray, it is the pressure of competitive design and the necessity to follow-through ideas into rigid implementation that results in successful innovation. He suspects that many people have ‘bright ideas’, but that they lack the experience and the motivation to carry it through to fruition: ‘They have this great idea and then they lose interest.’

  However, he also admits that not all his racing car design innovations have been successes; he has had a share of failures, too. One of his largest failures was the Brabham ‘surface cooling’ car. This radical concept was meant to be several steps forward at once; reduction in weight, improvement in driver safety, and what was meant to be a long-term technical advantage over the opposition. His imaginative idea of ‘surface cooling’ was to do away with normal radiators for cooling the engine, and instead to pass the water and oil through surface heat exchangers built integrally into the monocoque structure: the ‘skin’ of the car was both structure and radiator. Other refinements included improved monocoque form, elaborate electronic engine and lap-time instrumentation systems for the driver, carbon-fibre brake discs, and an on-board air jacking system for quicker tyre changes.