LOTUS 72 GRAND PRIX CAR
"To contest World Constructors and Drivers Championship Honours during 1970, Team Lotus introduce their
new contender, the Lotus 72. This is primarily the work of Maurice Phillippe, the Chief Designer for Team Lotus
and represents a vast step forward in concept from previous Grand Prix cars.
All aspects of the car involve new and radical thinking to produce the best possible compromise. In
appearance the most striking visible features are the location of the radiators amidships, and the ultra low build
of the aerodynamically designed wedge shaped body, which have evolved from study of models in the wind
tunnel.
Power comes from the Ford Cosworth DFV, V-8 engine, which although originally designed for the Lotus Type
49 car in 1961, now powers most of the successful cars in the Grand Prix field. For this reason, it was decided
that the chassis for this new Lotus must be considerably more advanced technically than any of its rivals.
As already mentioned aerodynamic considerations were given a high priority, and to improve penetration, as
well as avoiding long water coolant pipes running from end to end, the radiator has been moved from the
conventional location in the nose and replaced by two smaller radiators amidships. These are located in fully
streamlined glass fibre ducts. The main chassis is a nacelle, of the now well established, monocoque type of
construction, with panels forming the driving compartment and fuel cell cavities. The inner skins are mainly
20.S.W.G. L-72 Aluminium Alloy, whereas the outer panels are I8 S.W.G. NS-4 Aluminium (Magnesium) Alloy.
To preserve the airflow into the upstream radiator intakes, the outer panels are carefully contoured throughout
their length.
A further refinement, is the flush rivetting employed for all external surfaces. The engine is cantilevered as on
the Lotus 49, and attaches to the rear of monocoque section through four 3/8' diameter bolts. The forward end of
the monocoque embraces a steel sub-frame, formed mainly from 5/8" square tubing, which distributes all the
loads from the front suspension members.
The front suspension breaks new ground, in that, the springing medium is in the form of a compound torsion
bar, operated by a link system connected to the top wishbone. This allows the torsion bar to be mounted,
together with its attendant damper, well inboard, and the linkage is arranged to provide a progressive spring
rate. The torsion bar comprises a solid inner shaft, with a tubular outer member. Suspension loads are
transmitted to a lever at one end of the solid shaft, twisting it in the process, and in turn twisting the outer
tubular shaft, to which it is joined at its other end, by a splined coupling. The tubular outer shaft then passes
the torsional loads back and over the inner solid bar, to another lever which is anchored to the chassis. In this
way, the length of the torsion bar is considerably reduced, and the torque reaction is reacted at the same end of
the bar, since the two levers are adjacent, whereas, with a conventional torsion bar the reaction is transmitted
along the length of the chassis equivalent to the length of the bar. Wishbones are fabricated from argon arc
welded, nickel, chrome, molybdemun alloy steel sheet, and pivot on solid dry bushings. The suspension upright
is in magnesium alloy and the axle is the live type, in order to transmit drive to the front brake.
The front brakes are mounted well inboard and are driven through C.V.joints the in boards being of the
plunging type to accommodate shaft length changes during suspension travel. The disc and caliper are
mounted on an ultra-light magnesium casting. Because there is no difficulty in providing adequate cooling air,
the disc is of the solid type.
Steering is by a lightweight rack and pinion having a spiral tooth form, the rack casing being an all aluminium
alloy fabrication. An aluminium alloy univeral joint connects the steering column to the pinion.
The rear suspension has similar revolutionary features to the front and incorporates progressive rate,
compound torsion bars for the springing medium. The suspension is carried on a primary steel 'C' frame, which
attaches at several points to the engine, bell housing and final drive housing and a secondary aluminium alloy
frame, which sandwiches between the gearbox halves. A triangulated top wishbone, fabricated in alloy steel,
combined with a radius arm, provides positive location of the finned magnesium alloy upright in the steered
plane. The lower wishbone is also triangulated and has an extremely wide base, which avoids the requirement
for a lower radius arm.
Rear brakes are also mounted inboard and are carried on magnesium alloy adaptor castings to the final drive
cover plates. As at the front, the disc is of the solid type mounted on a light alloy centre.
Drive from the engine is transmitted through a 3 plate clutch to the 5 speed gearbox. The final drive transmits
out to the wheels via C.V.Joints and solid steel shafts, the inner joints being of the plunging variety.
13 inch diameter wheels at the front and 15 inch diameter wheels at the rear, in cast magnesium alloy, are
surmounted by the latest tyre equipment from the Firestone Tire and Rubber Company, and incorporate safety
bolt fittings to the tyre beads.
45 gallons of fuel is carried in three rubberised fabric fuel cells, two in the monocoque side cavities and one in
the seat cavity. Oil is carried in a saddle tank mounted over the gearbox, and incorporates an integral catch
tank and oil cooler.
Special attention was given to the cockpit shape to ensure adequate arm and elbow clearance, yet minimise
loses of fuel capacity. This resulted in sloping sides to the cockpit. Due to the low depth of the monocoque
section, it is surmounted by a deep one piece easily removeable screen, which is flanged at its lower edge to
allow direct attachment to the top surface of the monocoque.Cables and other services pass through an easily
removeable duct on the left hand side of the cockpit for ease of servicing.
The fibre glass nose incorporates fixed angle wing root stubs, which may be fitted with alternative sections of
wing for adjustment purposes, and is generally steeply angled to provide extra nose down pitching movement. A
small tubular sub-frame transmits the aerodynamic loads to the chassis, and incorporates mountings for the
automatic fire extinguisher and battery. The rear wing is of the slotted type and is designed for high efficiency,
mountings being provided on the primary rear suspension frame.
Due to the attention given to weight reduction the Lotus 72 will be down to within striking distance of the current
Formula One Regulations, of 530 kgs. including oil and water"
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