|wb: 7ft. 3in.
CONVINCED that in wood there are as yet unrealized possibilities as a material for car construction, Frank Costin, an aircraft engineer well known for his work for Lotus and Vanwalls in the past, has designed and built a small two-seater Coupé with a plywood structure. Clearly, a light yet rigid chassis for a sports car can readily be made as a welded, multi-tubular structure, or it can be formed entirely in glass fibre. Costin maintains that because the light tubular chassis is prone to fatigue troubles, and costly moulds and jigs are required for glass fibre, an alternative material has to be sought. Light alloys are a possibility, but corrosion and fatigue problems are difficult to solve. He was led, by these considerations, to the use of wood, which has been employed in a number of aircraft fuselages. With correct design, a car chassis in this material can have ample strength and a very high stiffness-weight ratio. Fatigue and corrosion are non-existent, the raw material is inexpensive, and damage is easily repaired. From the sketch of the new car's basic structure it can be seen that aircraft design techniques are employed. Strength is derived mainly from two very deep longitudinal box-section members, one at each side, made from plywood, with stiffening diaphragms along their length. These are joined at the front by a reinforced plywood box with bolt-on steel pick-up points for suspension wishbones and steering gear mountings. Amidships, a transverse box forming engine bulkhead and facia ties the side members to the transmission tunnel, which also contributes strength. Seat foundations and the front wall of the boot, all in plywood, are further transverse members which reinforce the structure, and there are rigid, box-section pillars for the rear window which support the roof. The roof panel adds little to the stiffness, and gull-wing doors are incorporated, with transparent plastic panels in their upper surfaces. Birch and Douglas fir or spruce are used throughout, and all joints are glued. All wood is impregnated under pressure with protective and fire-resistant compounds. Torsional stiffness of the structure is 3,000 lb ft per deg-a very high figure-and the weight complete with doors, screen, seats, and including brackets for suspension, steering and radiator is approximately 1½cwt.
Existing, easily obtainable components are used. The engine of the prototype is a 1,172 c.c. Ford, but in production the 997 c.c. 105E o.h.v. Anglia engine (tuned by Wilen Engineering) and gear box will be available, inclined to the right to reduce bonnet height. Back axle and all wheels are Metropolitan, rear suspension being by coil springs and forward-facing parallel radius arms; the axle's transverse location is by a Panhard rod. Front suspension and steering is by Alford and Alder, as used on the Triumph Herald, and Girling brakes are fitted. Weight of the complete car, with two gallons in the 6;-gallon rear tank, is only 8cwt. Main dimensions are : Wheelbase 7ft 3in; track, front 4ft, rear 3ft 9in; overall length 12ft 1in; width 4ft 7in. Design has been carried out in conjunction with Jem Marsh, of Speedex Castings and Accessories, Ltd., 17a, Windsor Street, Luton, Bedfordshire, who are sole distributors. At present it is intended to produce the Marcos G.T. in component form only, and a price has not yet been fixed.
(The Autocar, March'60)