User:Pyrope/Sandbox 7

Chassis and bodywork

While the 701 had used a simple and easy to manufacture, open-topped, 'bathtub' style aluminium monocoque, in which the driver sat covered only by fibreglass bodywork, the 711 had a more complex, semi-cylindrical structure, which the driver sat partially inside with their legs covered by the chassis itself.^[2] Although being more difficult to design and build, this "full monocoque" was much stiffer than the older car's chassis, and it allowed all the fuel to be carried within the body of the car, rather than relying on external tanks for longer races as the 701 had.^[6] This monocoque was constructed in 16- and 18-gauge aluminium alloy, and was reinforced in front and behind the driver with 3⁄16 inch thick duralumin plate bulkheads.^[2] In front of the front bulkhead, a tubular subframe extended forward to carry the front suspension and inboard brakes.^[2]

Perhaps the 711's most distinctive characteristics were its bodywork and aerodynamics.^[2] In a significant departure from the Lotus 72 template, Herd had decided that his car should be designed around reducing as much as possible the aerodynamic drag incurred by the bodywork.^[6] While the Lotus used its wedge-shaped body to generate significant downforce, in addition to that generated by the car's wings, this did mean that the body also generated more drag. In order to realise his plan, Herd enlisted the help of leading automotive aerodynamicist Frank Costin. Costin had been one of the first to apply serious aeronautical aerodynamic theory to racing cars, starting with the Lotus Mark VIII sportscar in 1953, and moving into Formula One with the Vanwall in 1956.^[7] For the March 711, Costin decided that

Engines and transmission

As has been widespread practice since the introduction of the Lotus 49 in 1967, the March 711 used its engine as a fully-stressed, load-bearing part of the car's structure. In common with the 49, the motor that this structure was designed around was the Ford-funded, Cosworth-designed and built DFV 2,993 cc (182.6 cu in) 90° V8 engine. This unit was available to buy by anyone who could meet Cosworth's £7,500 price tag

Fortunately for Herd, the chassis mounting points on the Cosworth and Alfa Romeo engines were in the same place,^[6] allowing the two to be used almost interchangeably with only minor modifications. Indeed, some chassis were run with both engines during the course of their active career.^[5] The only major packaging difference between the two engines was in the location of their alternators, as the Cosworth integrated its unit within the main body of the engine, while the Alfa Romeo alternator was separate. March chose to mount this component on top of the gearbox.^[6]

In common with the majority of contemporary Formula One cars using Cosworth engines, the March transmission was based around a Hewland gearbox. However, while its predecessor had used Hewland's heavier duty DG300 model, the 711 was designed around the lighter FG400. This gearbox was a hybrid of the stronger differential, crownwheel and pinion of the DG300, mated to gears made to the smaller and lighter size used in the Formula Two-specification FT200 'box. Where in previous seasons these gears would have been too delicate for the DFV's torque output, improvements in Hewland's manufacturing and quality control meant that they could now be used for the Formula One machines.^[6] Herd reckoned that using the lighter gearbox saved around 20 lb (9.1 kg),^[6] and that as this weight was saved from the extreme rear of the car the benefits were not limited to simply the reduction in overall mass.

Both Lotus and Tyrrell had already successfully mated the DFV and FG400 in their Formula One cars, so this was a proven combination from which most of the teething issues had been eradicated. However, the Alfa Romeo T33 had only previously been run using the DG300, so March had to pioneer this combination.^[6]

Braking and suspension

As they had performed very reliably over almost 35,000 miles (56,300 km) of racing and testing during 1970, Herd carried over the 701's Girling brakes and Ferodo pads to the 711's braking system.^[6] The discs themselves were 10.5 in (27 cm) diameter ventilated units at each corner, with Girling's stiff and powerful E-type calipers at the front, and their lighter AR-4 units at the rear.^[6] Initially, the 711's brakes were mounted inboard both front and rear, actuated by driveshafts of identical design. March had previously found that the approximately 25% reduction in unsprung mass resulted in improved compliance over bumpy surfaces and consequent roadholding and handling benefits, which were worth the trouble despite the added complexity.^[6] March had switched the 701 from outboard to inboard rear braking part way through the 1970 season, so had experience with this system, but the decision to run inboard brakes at the front on the 711 was new to the team.

Having an inboard braking system imposed some restrictions on the choice of suspension design. In particular, the need to fit both steering arms and brake driveshafts within the front suspension geometry dictated that the spring and damper units be mounted either in an inefficient outboard location, or inboard, within the chassis. Herd decided to take the latter option.^[6] The front suspension itself was of a conventional double wishbone design, but with the forward arm of each upper wishbone extended behind its chassis pivot point to act as a rocker arm to actuate the inboard-mounted coilover spring and damper units. In addition to the limitations on space, mounting the springs within the chassis also removed them from the airflow, reducing drag and improving the feed of cold air to the radiators mounted between the front and rear wheels.^[2]

At the rear of the car, in place of the previous model's twin parallel links set-up, Herd chose to use a one-piece lower wishbone, but retained the transverse link and long radius arm in the upper position.^[6] Although the transverse link and wishbones were attached directly to the engine and gearbox, the radius arms were long, and extended forward, past the engine, to be attached to the rear bulkhead of the monocoque.^[2] The choice to switch to a partial wishbone configuration was down to Herd's intention to build in some degree of anti-squat geometry to the design – to resist suspension movement caused by acceleration – as the complex links and swingarms used with the 701 would have taken up too much space and interfered with exhaust pipe routing.^[6] As the inboard brakes at the rear could be mounted to the existing driveshaft from the gearbox, and there was no need for steering arms, the coilover units could be mounted in a conventional, outboard location.

Ancillaries

As with the previous season, March's contract with Firestone dictated that the car was designed around that company's tyres. However, the withdrawal of Dunlop from Formula One at the end of 1970 meant that the only alternative supplier was Firestone's fellow American company Goodyear, who manufactured tyres in the same range of sizes as Firestone. Hence, in practice, the choice of tyre was less critical to the handling of the car than had been the case with the 701. The works team of course ran with the Firestone product, but the Williams and Barber cars were run on Goodyear rubber.

Teams and drivers

March's relationship with its 1970 drivers had not ended well. Former team leader, Chris Amon, had been promised that the works team would be set up around a single car entry for him, but by the end of the season March were running a two- or three-car team at every race, and had been providing support for up to five customer entries as well. The demands being made by Amon meant that their second driver, Jo Siffert, felt that too much of the team's efforts were being spent on Amon's car and not his.^[2] Both drivers decided to leave the team at the end of that season. Thus, before the 1971 Formula One season got underway, March were looking for two new works drivers.

The first person that March signed for 1971 was a driver with almost already a two year relationship with the still relatively new team. Young Swedish driver Ronnie Peterson had been the first person to experience a March car in competition, when he drove the team's experimental March 693 in selected rounds of the British Formula Three Championship in 1969. The following year he had driven for the works-supported Malcolm Guthrie Racing in the European Formula Two Championship, driving a March 702, and had been placed in a Formula One drive at Colin Crabbe's Antique Automobiles Racing Team by March, who provided a March 701 to the team.^[2] Although this experience meant that Peterson was not a complete rookie, he was significantly more inexperienced than normal for a works team's lead driver.^[2]

The works' supporting drivers were largely dictated by March's financial circumstances, either tied to their engine supply relationship with Alfa Romeo, like Andrea de Adamich, or bringing in significant external funds, like Alex Soler-Roig or Nanni Galli.^[2] De Adamich had been part of the Autodelta race program since 1965, and won Division 2 of the European Touring Car Championship for the team in 1966, in an Alfa Romeo GTA. He had been placed at the McLaren Formula One team in 1970 when Autodelta started providing them the Alfa Romeo T33 engine, and he followed the engine to March in 1971.

Frank Williams was the first external 'privateer' team owner to commit to buying a 711.^[6] The car was bought to run former Matra works driver Henri Pescarolo, who brought financial backing from the French Motul lubricants company. At the same time, and to tide the Williams team over until their 711 was ready, Williams also bought an ex-works 701.^[2]

1971 Formula One season

1972 Formula One season

SCCA Continental Championship

Formula One World Championship results

(key) (results in italics indicate fastest lap)

¹ March-Ford finished equal on points with third-placed Ferrari, but were placed fourth as Ferrari had won races in 1971.
² Includes 12 points scored by March 721X and March 721G entries.

Non-championship Formula One results

(key)

SCCA Continental Championship results

(key)