March 701
The March 701 is a Formula One racing car model, designed by Robin Herd with Peter Wright, and built by March Engineering. The 701 was March's first Formula One design – following their one-off March 693P Formula Three prototype of 1969 – and was designed and built in only three months. The March 701 made its race debut a month after its public unveiling, at the 1970 South African Grand Prix. In total, eleven 701s were constructed, with March supplying many privateer entrants as well as their own works team. The 701's career started well, March drivers taking three wins and three pole positions from the car's first four race entries, but lack of development through the 1970 Formula One season resulted in increasingly poor results as the year wore on. The 701 was superseded by the March 711 in 1971, and made its last World Championship race appearance at the 1971 Italian Grand Prix.
Design
March Engineering was set up in September 1969 by amateur racing drivers Max Mosley, Alan Rees and Graham Coaker, with engineer and former McLaren and Cosworth racing car designer Robin Herd. After producing their first prototype, the 693P, in Coaker's garage Max Mosley announced that March would enter a car for the first Grand Prix of the 1970 Formula One season. Designer Robin Herd started work on the car in November 1969, and by the 701's official press launch on 6 February 1970 two cars had been finished and were ready to run. In order to complete the car in the short time available Herd had been forced to take a "British Standard" conservative approach and held over more advanced features for the 701's 1971 successor, the March 711. L. J. K. Setright, writing in Car Magazine, described the 701 as "a Chinese copy of a McLaren Lotus" and suggested that "to make a better 1967 car in 1970 is just being wise after the event." Interviewed in 2010, Herd stated that at the time he was "disillusioned by the 701, because it was nothing like the car I wanted to build." The stress and workload involved with getting the car finished to Mosley's ambitious deadline meant that Herd lost over a stone and half in weight.Following the conventions laid down with March's first design, the car's name encoded both its year of design and the intended class of competition. Mosley calculated that each car cost £2500–3000 to build, and had initially planned to sell them to customers for £6000 apiece. However, Walter Hayes of Ford of Europe, who were funding Ken Tyrrell's purchase of two cars for his privateer team, persuaded him that he should in fact be charged £9000. In total, eleven March 701 chassis were constructed – three works cars and eight for sale to customers – and as of 2012 at least ten of these were known to survive.
Chassis and bodywork
The 701 was built around a "boxy and workmanlike" bathtub monocoque chassis – constructed from L72 alclad aluminium sheet with cast magnesium bulkheads – that carried the engine as a stressed member. Most of the 701 chassis produced were manufactured in 18 swg sheet, although a special lightweight car, chassis 701/6, was built for the works team during the 1970 season using lighter 20 swg aluminium, although they never raced that car. One of the Tyrrell cars, 701/4, was also rebuilt with a 20 swg monocoque early in the course of the season.Ahead of the car's forward bulkhead the brake cylinders, fire extinguisher system, battery and radiator were carried on a tray-like extension to the cockpit floor pan, constructed in lighter 20 gauge aluminium sheet. Herd did consider using side-mounted radiators, but these were too complex to design and build in the time available. The car's fibreglass nose bodywork enclosing the radiator was relatively square, with a near-rectangular opening for the radiator intake. On either side of the radiator opening Herd placed small wings to generate downforce, moulded with the radiator cowl as a single unit. These wings were fixed in position, braced with a steel tube that spanned their full width, and carried adjustable trim tabs along their trailing edges. At the rear of the car a large, single-plane, adjustable wing was mounted atop the gearbox, between the rear wheels.
One of the 701's visually distinctive features was the aerofoil shape given to the detachable side-mounted external fuel tanks, positioned between the wheels. Before the start of the 1970 season Herd had reckoned on the car requiring a fuel capacity of "well over" 40 gallons for each race. Each of these side-mounted tanks contained six gallons of fuel that, combined with the main tank behind the driver's seat and two tanks on either side of the driver within the monocoque, gave the 701 a total fuel capacity of 60 gallons. The tanks' profile was created by Peter Wright, who at that time worked for March's bodywork contractor Specialised Mouldings. Although the aerofoil shape was claimed at the time to produce "downthrust" and aid stability, Herd has since stated that in the turbulent air between the wheels they would only have been marginally effective.
Engine and transmission
Again following conventional practice, to propel the car Herd employed the tried and tested combination of a Ford-Cosworth DFV engine mated to a Hewland DG300 five-speed gearbox. The DFV was a 90° V8 engine, and in its original form developed around. Following the pattern established in Formula One by Keith Duckworth for Colin Chapman's Lotus 49 of 1967, the engine was mounted behind the driver and formed a stressed component of the car's structure. The rear suspension and engine ancillaries were all directly mounted to the engine and gearbox themselves, rather than a chassis subframe. The only exceptions were the suspension radius arms, which transmitted fore and aft loads directly into the monocoque.Suspension and ancillary components
The 701's rear suspension was a relatively conservative twin link and radius arm system, with coilover spring and damper units mounted outboard of the car's bodywork, in the airflow. Double wishbone suspension was employed for the front wheels, which Herd described as "slightly unconventional for a current formula 1 car", again with the spring and damper units mounted outboard. Herd attributed his choice of the double wishbone system to a desire to overcome the suspension geometry compromises necessary to accommodate the increasingly wide front tyres of contemporary Formula One, while outboard shock absorbers – despite aerodynamic disadvantages – provided advantages in simplicity, cooling and stress management.Braking duties were performed by Girling disc brakes at each wheel. These were initially positioned within the car's wheel rims, but for the second race of the 1970 season, in Spain, March switched the works 701s' rear brakes to an inboard design, that Herd estimated reduced the car's unsprung mass by approximately 25%. All other 701s were converted to the same specification over the subsequent few weeks.
The wheels themselves were to March's own design and employed the single centre stud fixing method that Herd had pioneered on the abortive Cosworth four-wheel drive car of the previous year. Some reports state that Herd had intended them to be in diameter all round, but that March were forced to specify rims at the rear in early races due to a lack of suitably developed 13 in rear tyres at the start of the 1970 season. However, Herd has also stated that he was forced to make the switch to 13 in because Firestone reduced the size of their tyres. Once the cars' brakes had been modified to the inboard design 13 in rims could also be employed at the rear.
Another visual hallmark of the 701 was its combined oil tank and de-aerator. This large, cylindrical tank was mounted vertically to the right hand side of the Hewland transaxle, filling the space between the right rear wheel, the gearbox and the wing. Autocar sporting editor Innes Ireland described it as "enormous" and looking "like an old fashioned coffee percolator". The oil radiator itself was mounted atop the gearbox, to avoid the surge and starvation problems associated with the lengthy pipes needed to mount the radiator in the nose, alongside the water radiator.
The Tyrrell cars
Although the chassis monocoques for 701/2 and 701/4 had been manufactured by March, the final buildup of the cars was by Tyrrell mechanics. As a result, the blue Tyrrell cars incorporated a significant number of differences and tweaks in their configuration to the cars run by the works March team and those supplied to other customers. The first major difference was the specification of Dunlop tyres, rather than the Firestone rubber with which the works cars were equipped and the 701 had been designed around. In an attempt to develop the car and improve its handling the Tyrrell team made adjustments to the position of the suspension mounting points and added a damper to the steering system. More subtle variations related to the positioning of exhaust pipe brackets, wing struts, the oil radiator, and the pipe runs for lubrication and coolant fluids.Following the first race in South Africa the Tyrrell team also made adjustments to the design of the front wings. They removed the fixed, fibreglass items integrated into the nose cone that had been supplied by March and replaced them with adjustable aluminium aerofoils. These could pivot about a horizontal axis to alter the whole plane's angle of attack. An additional benefit was that they were removable, to reduce drag, and Stewart's car made use of this for the Italian Grand Prix at the high-speed Monza circuit.
During the 1970 season Ken Tyrrell became increasingly critical of the 701's shortcomings, in particular targeting the fact that the car was over the mandated minimum weight limit. However, Herd had deliberately prioritized reliability and safety in the car's design, in large part due to influence applied by Tyrrell and Stewart.