artomotive

Classic cars, defined by the human hand

Prototype Parade No. 30 | Model Maker May 1951 | Drawn by Maurice J. Brett

4.5L Bentley Le Mans

H AVING recently dealt with a number of sleek moderns, it was felt that another vintage type deserved a turn. When the choice had narrowed to a Bentley the temptation to pick the immortal "Blower 4 ½" was well nigh irresistible, but this urge was firmly suppressed on the grounds that, glamorous though the ex-Birkin short chassis car might be, it wasn't quite so fully representative of that glorious breed as, say a dyed-in-the-wool team car, with "inspiration by natural causes".

Now of all historic motor cars, no other make can boast of so many existing specimens, almost all in the pink of condition, with their dossiers safely in the keeping of the Mother Club, so once more I sent an S.O.S. to High Priest Stanley Sedgwick, Hon. Secretary of the Bentley Drivers' Club, who promptly and courteously referred me to YV 7263, in whose oil pipes circulates the pure untainted blood of the Bentleys. Its present owner, Mr. A. G. F. Oldworth, unhesitatingly afforded facilities for measuring up the car at his home at Cobham, and the car is drawn and photographed exactly as it exists today, very little changed since its racing heyday in 1929.

The 4-cylinder o.h.c. 4 ½ litre Bentleys "grew up" from the popular 3 litre cars in 1927, and in 1928 our hero YV 7263 first appeared as a works entry, driven in the Essex Club's six-hour race at Brooklands by Tim Birkin, finishing third at 72.27 m.p.h. Sharing the wheel with Jean Chassagne at Le Mum, Tim encountered fearsome tyre trouble, broke the lap record and finished 5th. Fifth position and fastest lap seemed to be this car's speciality during 1928 for the same story repeated itself in the Tourist Trophy, and at Boulogne, where Tim's 73.16 m.p.h. in the Georges Boillot Cup was an all-time record for the course. In 1929 the Hon. Mrs. Victor Bruce broke the Class C 24 Hour record at Montlhery in the same car, at 89.57 m.p.h., and it was then hurriedly prepared for Le Mans, in order to take the place of one of the blower cars, which were withdrawn. It's drivers, Lord Howe and Bernard Rubin, did not regard their chances of finishing as rosy, in view of the somewhat sketchy preparation, and their pessimism was justified when a magneto cross-shaft broke in the early stages of the race, and YV 7263 retired. By way of compensation, however, the old car carried B. Harcourt Wood into 4th place in the Irish G.P. and finished 5th once more in the 500 miles race, driven by the Hon. Brian Lewis and C. W. Fiennes. This brief biography of the Bentley as a "team" car concludes on a somewhat melancholy note with the retirement of Williams and Durant in the 1930 "Double Twelve" after a minor fire and axle trouble, but is more than sufficient to justify its place among the great ones of the past.

Bentley 4.5L Le Mans cutaway drawing

As perhaps, together with the 30/98 Vauxhall, the best known sports car of the old school, the general technical details of the 4 ½ litre Bentley will be familiar to most readers, although if its development were to be discussed in detail many pages could be written. By the time YV 7263 was built, a more sturdy frame and the large wide shouldered radiator marked these cars as bigger brothers of the 3-litre, and for Le Mans in 1928 the bodies were somewhat different from that shown in our drawing, having tank and spare wheels enclosed in a short "manxed" tail fairing. The classic open body is shown here, however, as the car was restored to this style, plus the addition of a luggage boot ahead of the fuel tank. The wings extend in a more generous arc than those fitted for Le Mans, and the third central headlamp is replaced by a lower placed pass-light carried above the front cross bracing. The typically Bentley lever-and-cam-action filler caps are fitted to the radiator and fuel tank, and another reminder of its racing days is the wheel adjuster for the brakes in the driving compartment floor. Other interesting external features for the modeller are the double Hartford shock absorbers, two pairs ahead of the front axle, and a pair before and behind the rear axle, and the trussing of the chassis side members, rather reminiscent of a railway coach! An external filler for the scuttle oil tank projects on the near side of the scuttle top, and the two-panel windscreen folds forward. The Rudge hub caps are of the offset ear variety, and these, in fact, form the motif of the Bentley Drivers' Club, so they should be correct in the model I hope you are going to make!

There are no valances below the frame, and the exhaust system is visible from the near side, terminating in the massive fantail, which used to be sprayed heartily with a fire extinguisher during refilling operations!

The dashboard is a most satisfying sight, with an array of instruments that wouldn't shame a fighter aircraft, all of which had to be read and memorised by the well disciplined team drivers in days gone by. The large revolution counter is centrally mounted, and reads to 6,000 r.p.m. though for practical purposes the needle is "in the red" between 3,500 and 4,000.

In addition to pressure and temperature gauges, speedometer, clock and ammeter, the instrument panel carries the air pump for the fuel system on the left of the rev. counter, and an array of switches for the lighting and dual magnetos. The large spring spoked wheel is corded, and has centrally mounted ball-ended controls for ignition and throttle, under a domed cover. A leather grab handle is fitted to the scuttle beading, the gear lever works in a gate on the driver's right, inside the body, with the handbrake external. An interesting feature is the brake linkage, which passes through the rear passenger partment.

The Bentley is, perhaps, hardly an ideal subject for a powered model, as the thought of so majestic a vehicle either popping or screeching along under the urge of a small two stroke, is distressing to a degree. If, however, anyone can manage a four cylinder four-stroke, even with side valves, what better car could you find for it? I have recently found that a surprising number of people collect these drawings purely from enthusiasm for the cars themselves, and with no model making project in view.

It is also apparent, from correspondence received, that some readers would prefer very much more detail in these drawings, which would enable them to build super-scale models with accurate dummy engines, transmission, steering details and driving controls. At the moment the demand does not justify the immense amount of work entailed in treating every car described in this way, but the provision of super detailed drawings of a limited number of popular types is still under review.

Model Maker

4.5L Bentley Le Mans

Bentley 4.5L Le Mans technical drawing
Model Maker

Bluebird CN7

Bluebird-CN7 technical drawing

Prototype Parade No. 103 | Model Maker November 1960 | Drawn & described by R. B. Campbell

Bluebird CN7

400 M.P.H. That was the target and on the Bonneville Salt Flats in Utah four contenders had gathered to try and capture the Land Speed Record. Athol Graham was the first to try, but regrettably he lost his life when his car got out of control. Dr. N. Ostich had brought along a pure jet car, not strictly eligible for the contest, but at 200 m.p.h. it became unstable and so it was withdrawn. Micky Thompson reappeared with his car Challenger I, now fitted with Roots superchargers, and set up the fastest time yet at 406 mp.h. in one direction, but on the compulsory run in the reverse direction the transmission failed and that was the end of his attempt. During this period the Bluebird C.N.7 was making trial runs at progressively higher speeds. Then, at 365 m.p.h., disaster struck; the car spun round and careered out of control over the salt. The two right hand wheels were torn off but the car came to rest without breaking up any further. Donald Campbell was pulled out, bruised, badly shaken and bitterly disappointed. The attempt to regain his father's crown had failed.

The cost of this venture was about £1,000,000, and sixty eight firms co-operated in supplying the materials and undertaking the research necessary to build this powerful car. Four years work was put into the design and building of the Bluebird and now it lies a shattered wreck. Although photographs show the Bluebird to be substantially in one piece the severe battering that it received as it bounced over the salt means that it may take some months to repair the car for another attempt.

As the latest in a long line of record breaking cars, the C.N.7 had a glorious pedigree behind it. 175, 207, 246, 254, 272, 277, and 301 m.p.h.- at these speeds had the previous Bluebirds captured the Land Speed Record when piloted by Donald's father, the late Sir Malcolm Campbell.

Designed by Norris Brothers Ltd., who previously designed the Bluebird jet hydroplane, and built by Motor Panels Ltd., the C.N.7 is a car of ingenious and unique construction. The shape of the body had to be carefully planned to avoid aerodynamic lift which might tend to make the car become airborne at a high speed. No tail fin was fitted to give the car directional stability, but the huge wheels act as gyroscopes and assist in keeping the car on course. Thirty feet in length and weighing nearly four tons, this giant car is propelled by a Bristol Siddely Proteus Type 705 gas turbine. The regulations relating to land speed record attempts state that the car must be: "... a land vehicle propelled by its own means, running on at least four wheels ... , the steering must be assured by at least two wheels and the propulsion by at least two wheels ...", so plain jet propulsion as used in aircraft is not acceptable. In the C.N.7 the power turbine of the engine is separate from the compressor and is coupled to the wheels by spiral bevel gears at each end of the engine. The characteristic of the gas turbine is such that no gear change or clutch is necessary and the engine may be taken up to full power without waiting to warm up. This last fact saves on the amount of fuel that needs to be carried and the Bluebird only carries 25 gallons of B.P. turbine fuel, just enough to complete two runs over the measured course. All four wheels are driven to give maximum acceleration with minimum tyre wear. A free-wheel device in the form of a Reynold's "Spragg" clutch is fitted in the front transmission to compensate for the slight decrease in the front tyre diameters under braking conditions.

The success of record attempts depends very greatly on the life of the tyres. The huge tyres for the Bluebird are 52 inches in external diameter and 7.8 inches in section; they were made by the Dunlop Rubber Co. and inflated with nitrogen gas at 200 p.s.i. These tyres were tested at Fort Dunlop on a very special machine which spun the wheels to speeds in excess of 500 m.p.h. As the effect of a tyre bursting at this speed would be very dangerous to the operators, the machine was watched by closed circuit television. The tyres have no tread pattern and the thickness of the rubber on them is only two-hundredths of an inch! If it were thicker it would be thrown off by the centrifugal form generated as the wheels revolve at 3,000 r.p.m. Besides supporting the weight of the car and transmitting the power of the engine, the tyres have to withstand the braking forces, so the braking has to be carefully controlled as a skid would tear the rubber off the tyre with disastrous results. A wheel slip indicator is fitted in the cockpit so that any tendency for the wheels to skid or spin can be noticed and corrected. The four wheels are independently sprung and because of the tremendous loads carried they were made from steel discs. To facilitate fitting the wheels have detachable rims. The wheels were also made by Dunlop.

Bluebird-CN7 painting

It is obvious that the brakes cannot be applied hard at 500 m.p.h. because of the very grave danger of skidding. So, at the end of the run, when the throttle is shut the air drag starts to slow down the car, the air brakes are extended to add more drag, and when the speed has dropped enough, the brakes are applied very gradually. On the Bluebird the brakes are special Dieting disc brakes 16iin. diam. and mounted inboard to save unsprung weight. When in use the discs glow red hot ! Because of this tremendous heat hydraulic fluid could not be used in the braking system as it would immediately boil; in its place the brakes were operated by compressed air.

The chassis of the C.N.7 is of unique construction. There is no space frame but instead four deep longerons which run the full length of the car and which are shaped to the profile of the body. Elliptical formers are fitted to the longerons to complete the frame, which is covered with a light alloy skin. The longerons themselves are of an unusual material, Ciba Aeroweb, a ¼in. thick honeycomb sandwich of two 18 gauge aluminium alloy sheets separated by a honeycomb of aluminium foil only .002in. thick, the whole being bonded together with a Redux metal to metal adhesive.

Was all this effort in vain ? The Bluebird only made five trial runs over the course whilst alterations were made to the steering ratio and radio equipment, but the speed was gradually creeping up and when the target of 400 m.p.h. was almost in sight the car crashed. The measured mile is in the centre of a fifteen mile course so the Bluebird had seven miles in which to accelerate and finally seven miles in which to slow down, not a great deal of room at these speeds. The Bluebird could cover the total distance in about four minutes. Two runs must be made over the course, one in each direction, the second run to be made within an hour of the first. This is to avoid any advantage of sloping ground or tail wind. The average speed of the two runs is taken as the official record figure. On the fifth trial run the Bluebird ran over a patch of soft salt causing the car to lose traction on one side, which resulted in a spin and from then on events happened too fast for accurate observation. The C.N.7 appeared to skid for 300ft. then lift into the air to come down 608ft. further on. It rolled on to its side and continued to bounce across the salt for 1 ¼ miles. Two wheels were torn off, the front one complete with its cowling, but the rest of the car stayed intact. So ended what must have been the most highly organised attack on the Land Speed Record of all time. Let us hope that the damage to the Bluebird will soon be repaired and that another, successful, attack can be made on the Land Speed Record. The target is still 400 m.p.h.

Miniature Auto

Brabham BT19

Brabham BT19 blueprints

Miniature Auto March 1967 | Described by Doug Nye & drawn by John Barber

1966 F1 Repco-Brabham BT19

T HE STORY OF LAST SEASON'S Formula 1 World Championship is something akin to that one about the tortoise and the hare, though the tortoise in question must be about the quickest ever, and the hare (or rather hares) quicker still.

When the upgrading of Formula 1 from a capacity limit of 1½ litres to one of 3 litres was announced in November 1963, the various Grand Prix constructors settled down to some original design thought and research. That behind the Ferrari, Cooper-Maserati, Eagle, McLaren, Lotus-BRM and BRM H16 has already been described in these pages, and in these articles the general trend towards strong and light, but expensive to build and difficult to repair, monocoque chassis, fitted with powerful and complicated multi cylinder engines has already been made apparent.

Odd man out among GP constructors was the Brabham Racing Organisation, for it was decided to run a spaceframe chassis car powered by a light and simple V8 engine based on an American production car block. Even as late as mid-1965 (the last year of the 1½ litre Formula) it seemed unlikely to the public that a GP Brabham would appear in '66. But, negotiations had been going on quietly with the Australian Repco engineering combine, and between the US and Mexican GPs Jack Brabham himself went down to Melbourne to see a prototype engine they had built for use in the Tasman Formula races.

This engine, to become known as the Repco-Brabham Type 620, had been built by Repco's experimental section, directed by Frank Hallam, and was designed by Phil Irving. It was of very simple design, based on a production Oldsmobile V8 block and, with single overhead camshafts to each bank, the 2½ litre prototype gave about 250 bhp at 8,000 rpm on carburettors. Not a lot, perhaps, but it had a very wide usable power band and prolonged testing had shown it to be very reliable. A capacity of 3 litres was reckoned to give about optimum performance from the design, and so it was decided in Melbourne to build such an engine for Jack to use in the first races of the new Formula. With Lucas fuel injection an output of more than 300 bhp was expected —nearly 100 more than the old ½ litre Climax engines the team had used, from a unit weighing only 25 lbs more and with no greater frontal area. Expected fuel consumption was only about 10 gallons more per race, and so it was obvious that the complete car needn't be a lot larger or heavier than the old 'one-and-a-halfs'. Jack said then that . . "a car that keeps crossing the finishing line in one piece will be picking up quite a few Championship points next year" — and how right he was!

The first 3 litre Repco V8 arrived in England at the start of December, and the Ron Tauranac designed BT19 chassis, originally intended for the never raced flat-16 cylinder, 1½ litre Coventry Climax engine, was suitably modified to take the new power unit. With about 290 bhp in this initial form, the BT19 Repco Brabham was first raced in the non Championship Fl South African GP at East London on January 1 last year, and it dominated practice to lead until about nine laps from the end when the injector pump seized and broke its belt drive.

It was an encouraging showing though, and the car was then flown down to Australia to run in the last two Tasman Championship events of the year, fitted with the 2½ litre V8. The trip was a bit disappointing, with just a retirement and one third place to show.

Now, back to Europe for the start of the Fl season there, and the Syracuse GP on May 1. Jack again drove the BT19 after a dash from Oulton Park where he had driven an interim sports car powered by a 4.3 litre version of the Repco V8 engine. But the trip was wasted, for the Fl car expired on only the second lap, leaving John Surtees' Ferrari V12 to win. The tables were turned two weeks later at Silverstone though, for there the BT19 notched its first win, ahead of Surtees and the red car.

The World Championship series commenced one week later with the Monaco GP, but Jack wasn't feeling too well and wasn't sorry when the gearbox broke after just 17 laps. On to Spa for the next round, the Belgian GP, and there eight cars were eliminated on the first lap, seven of them in crashes caused by a violent rainstorm on the back leg of the circuit. Jack got the BT19 out of a huge slide at about 130 mph, but didn't feel much like racing after that and just toured home to score his first Repco-Brabham Championship points with a fourth place.

Then to the French GP at Reims on July 3, and two Repco-Brabhams appeared on the grid for the first time, with Jack sticking to the BT19, and Denny Hulme appearing in a brand-new BT20 —externally similar to the original car, but on 15 inch as opposed to 13 inch wheels, and being almost totally different in detail design. It's history now that Jack won the race after Lorenzo Bandini's Ferrari broke its throttle linkage while leading —and by doing so he became the first ever driver to win a Grande Epreuve in a car of his own construction. Victory was all the sweeter with Denny Hulme finishing third in the new car, and then the next three GPs, the British, Dutch and German, were also won by Brabham and his BT19. The Italian GP saw Jack retire but clinch the title when his only rivals, John Surtees and Jackie Stewart, also dropped out. A second BT20 had been tried in practice, and was found to handle better than the faithful old BT19, but its engine was down on power and so the original car was raced.

The non Championship Oulton Park Gold Cup then came before the trip across the Atlantic for the US and Mexican GPs, and there Jack won again in the BT19, with Hulme right behind him in the BT20. The Formula 1 Constructors' Championship was won by Repco-Brabham at the US GP, when Lotus-BRM —the outsider— won and both the Brabhams and their only possible rivals retired, but with a brace of BT20s Jack and Denny finished second and third to Surtees' Cooper-Maserati in the Mexican GP, while the BT19 became the spare.

So, out of 11 Fl races started in 1966, the Repco - Brabham BT19 won six, finished fourth in one and retired from the other four —successes achieved perhaps by the failure of the opposition, but made possible by the intelligent combination of moderate power, high torque, light weight, good handling and a lot of driving skill. Four Repco V8s have been used during the season, putting out about 300 bhp at 7,800 rpm. Transmission has been via Hewland five-speed gearboxes —a more robust one, specially commissioned for the job, being used in the latter part of the season.

The BT20 differs most obviously from the early car in using 15 inch diameter wheels all round, instead of just on the rear as the BT19 did from the British GP on, but it also has more bulged side tanks and a two piece engine cover just covering the cam boxes on both sides of the engine. Colours are dark green with a gold stripe, and the cast wheels —which are of six-lobe design on the BT20— are a matt dark grey. Goodyear tyres and Esso fuels and oils were used all season.

Finally, the two works BT20s finished fourth and sixth in the first round of the 1967 World Championship, the South African GP, at the Kyalami circuit on January 2, Denny Hulme finishing ahead of Jack Brabham after both had had troubles on the way —and Denny had led for 59 of the 80 laps. Both are now racing 2½ litre Repco-Brabhams in the Tasman Championship series in Australia, and these new engines feature redesigned cylinder heads with the exhausts mounted in the vee of the engine as on the Ford engine shown in our Indy Lola drawings (December issue). If this arrangement is successful, it will be used on new Repco made pure racing blocks for the rest of 1967's 3 litre Formula 1 races.

Vital prototype statistics: Wheelbase, 7 feet 9 inches; front track, 4 feet 5½ inches; rear track, 4 feet 6½ inches; overall length, 12 feet 6 inches (including exhaust pipes); overall height, 2 feet 8½ inches (at roll-over bar); overall body width, 2 feet 6 inches; overall width across tyres, 5 feet 3½ inches (front), 5 feet 4½ inches (rear); ground clearance, 3¾ inches; tyre diameters, 1 foot 11¼ inches (front), 2 feet 3½ inches (rear); tyre tread width, 6¼: inches (front), 10 inches (rear).

Model Maker

B.R.M.

BRM 2.5L technical drawing

Prototype Parade No. 78 | Model Maker December 1956 | Drawn & described by Richard Collet

B.R.M.

J UST over a year ago, in August, 1955, a successor to the ill fated multi cylinder supercharged B.R.M. was announced; but so dissimilar are the two cars that the new model is virtually a successor in name only. The original B.R.M., which was fitted with a V-16 engine of 1½ litres capacity, was such a highly complex piece of machinery that it required an extended period of development before its capabilities could be displayed to the full. Such a long development period was in fact required that by the time the car reached its peak condition the Grand Prix formula to which it had been designed was obsolete and had in fact been replaced by the present formula for which the new car has been designed.

The B.R.M. project is now the property of Mr. A. G. B. Owen, chief of the Rubery Owen industrial group who bought it, lock, stock and barrel, when the B.R.M. Trust was wound up. Mr. Owen has formed a special subsidiary of his company, known as the Owen Racing Organisation, to sponsor and develop these cars, and the latest step in their programme has been the introduction of this new car.

In the past season the B.R.M.s have shown the potentialities of world beaters; at the majority of the meetings in which they have participated, at least one of the cars, usually that driven by Mike Hawthorn, has leaped into the lead and held that position for the first few laps. Unfortunately, they have, with equal consistency, failed to maintain their lead due to some mechanical fault or other which has resulted in their subsequent retirement. Nevertheless, this model has shown that it has probably the best acceleration of any racing car, and if increased reliability can be built in during the winter months of preparation, then 1957 should prove a. successful season for B.R.M.s.

The excellent acceleration mentioned above is due to the very large piston area of the over square four cylinder engine of 2½ litres capacity. In this detail, as well as many others, the prime mover follows contemporary practice; the combustion chamber, for instance, is hemispherical with inclined valves operated by twin overhead camshafts, and aspiration at present is by two twin-choke carburetters. Later, however, it is hoped to convert to fuel injection and a number of systems are believed to be under development at the present moment.

The chassis is somewhat less conventional than the engine and embodies many lessons learned from the original B.R.M.; it is a triangulated space frame with springing by oleo-pneumatic struts on all four wheels. The front suspension is operated by unequal length wishbones and the rear by a de Dion axle which is unusual in that it passes ahead of the centre line of the wheels. The 4-speed crash type gearbox, on the other hand, is mounted behind the axle and operated by a short, remote control lever on the driver's left. The steering is by rack and pinion and controlled by a three or four spoked, wood rimmed alloy steering wheel.

To cope with the continual demands made on the brakes during a race, disc brakes have been chosen for their anti-fade characteristics. Only three brakes are fitted however; two are mounted outboard on the front wheels where most of the braking effort is required, whilst the third is mounted on the propeller shaft and operates directly on the transmission. Pressed alloy wheels of Dunlop manufacture are fitted, held in place by three eared, knock off hub caps and shod, of course, with racing tyres. Fuel is carried in a tail tank whose filler cap projects through the embryo head fairing.

The principal dimensions are: Wheelbase, 7 ft. 3 in.; track front, 4 ft. 1 in., rear, 4 ft. 0 in.; length, 12 ft. 2 in.; height, 3 ft. 0½ in.; max. width of bodywork, 3 ft. 3½ in.; ground clear-ance, 4½ in.; tyre size, front, 5.25 x 16 in., rear, 6.50 x 16 in.

It is perhaps unfortunate that the B.R.M. could not achieve in its first season the success which seems to accompany the various Continental makes. The car was, in fact, withdrawn from racing before the season had closed, and the number one driver, Mike Hawthorn, was released by mutual consent from the contract which bound him to drive this car. Since then a good deal of work has been put into the car and in October a slightly modified version was tried out at Monza autodrome in the hands of Peter Collins and Tony Brooks. If the B.R.M. can be made sufficiently reliable to last out a full length grande epreuve, then it should be well to the fore in the struggle for Grand Prix supremacy in the coming year.

BRM P25

BRM P25
Model Maker

BRM F1 1958-59

BRM F1 1958-59

Prototype Parade No. 96 | Model Maker September 1959 | Drawn by J.H. Batchelor & described by J. Laidlaw-Dickson

BRM F1 1958-59

T HE 1956 B.R.M. was described and illustrated in Prototype Parade No. 78 in December, 1956. Since that date considerable changes have been made to the car, so that it is virtually a new machine. Alas, for all these changes it has retained its "hoodoo", and in ten years has won only one major race, the 1959 Dutch G.P., in the hands of Joakim Bonnier - though almost without exception has invariably held the lead in the opening laps, and earned near pole positions on the starting grid.

Latest of the long line of drivers who have "contracted out" of driving it is Stirling Moss, who, faced with the brake failure that wrote off Behra's car at the 1958 Goodwood meeting, showed his usual lightning reaction by deliberately spinning it off the course, and escaped with bruises and considerable disgruntlement. Subsequently, as a sporting gesture, a B.R.M. was handed over to the Moss racing group for their use, and Stirling tried his luck again, but with disappointing, almost dangerous, results.

At Rheims his car again failed to finish, though he gained a point for a new record lap at 130.5 m.p.h. In the British G.P. he did finish second, and shared fastest lap and new record at 92.31 m.p.h., but failed to extend Brabham in the Cooper-Climax. He joins a list of ex-B.R.M. drivers which included Fangio, Behra, Hawthorn and Collins. Which, as he says himself, is a terrible pity because the car is the fastest machine in G.P. racing today!

Since 1956 the principal changes in the appearance of the car include an increase of wheelbase from 7 ft. 3 in. to 7 ft. 6 in., and wider tracks which are now front 4 ft. 3 in., rear 4 ft. 2 in., overall length is now 9 in. greater at 12 ft. 11 in. Tidying up measures have improved the spiderlike exhaust pipes, which now come neatly down the bonnet side and, follow a low line along the car to the rear. For 1959 the air intake tube on the offside is further extended to finish almost directly over the radiator.

There is no doubt that Alfred Owen, chief of the Rubery-Owen organisation, is determined to achieve the same measure of success with the car that has attended his former co-operator on the original project, Tony Vandervell. In many ways the facilities and resources of the two organisations are similar, but so far a really important winning flag has escaped the B.R.M., though it always seems to be on the eve of great things.

In appearance, we consider it to be among the prettiest G.P. cars racing to-day, looking every inch a thoroughbred. Colin Chapman, successful designer of suspension on both Vanwall and Lotus, collaborated in the B.R.M. suspension, which is reminiscent of both these cars. It follows the usual de Dion style, with coil springs and telescopic dampers, and employs Watts linkage for lateral stability, a method also followed by Aston Martin.

The wider track of the present model has improved handling and at the front suspension is by modified wishbones, with coil springs and hydraulic shockers, plus an anti-roll bar.

In common with most G.P. cars today, gear-box is rear mounted with four speeds and reverse, a variety of ratios being available on the three lower gears. Final drive is via a ZF differential built integrally with the gearbox.

Wheels continue to be Dunlop centre-lock disc pattern, with the typical drilling all round. B.R.M. is almost the only car of its kind to remain faithful to them, wire wheels and the lighter magnesium alloy discs being the usual wear these days. Dunlop again continue to be responsible for the tyres which are either 6.50 or 7.00 x 16 at the rear and 5.25 x.16 at the front.

The engine continues as a 4-cylinder of just under 2500 c.c. capacity, fed by twin-choke Weber carburettors, though it is believed the original output of 250 b.h.p. at 8,000 r.pm. has been somewhat augmented if not yet approaching the near 300 b.h.p. claimed for the Ferrari.

The characteristic radiator cowling with its two central supporting sheets of metal is functional, as these act as an engine ventilation duct, the honeycombs of the radiator being placed on each side of this channel.

Brakes continue to be a somewhat touchy problem with the entrant. Something must certainly be done to make them failure-proof if first calibre drivers are to be attracted to the marque. In our ignorance, we should consider it a far from insoluble problem. Meanwhile, outboard servo-assisted Lockheed type are employed at the front, with a special inboard disc at the rear, in a constant stream of air provided by suitable cowls.

Model Maker

F1 Rear Engined B.R.M.

BRM F1 1960 technical drawing

Prototype Parade No. 102 | Model Maker October 1960 | Drawn & described by Walkden Fisher

F1 Rear Engined B.R.M.

A CCORDING to official Pronouncements, and despite the controversy which has raged during past months regarding the introduction of a new 1 ½ litre formula for 1961, the present year is likely to be the last for the 2 ½ litre Formula One. Also of considerable importance is the fact that 1960 will be outstanding in motor-racing history as the year which has seen a definite trend develop in favour of rear engined Grand Prix machinery, to such an extent that many technicians are now of the opinion that there is no immediate future for the "normal" single-seater.

Cooper and Lotus have scored sweeping successes with rear-engined cars, and the B.R.D.C. International Silverstone Meeting held in May this year saw the first appearance in competition of rear-engined B.R.M.'s. Following this, the 1960 Monaco Grand Prix which took place a few weeks later served as the event which introduced not only the rear-engined B.R.M.'s to the Grandcs Epreuves, but also a Ferrari "con motore posteriore". Information to hand also indicates that Mr. G. A. Vandervell intends to fall in line and proposes to install a Vanwall engine in a Lotus chassis. A further report also mentions the possibility of a rear-engined Scarab in the future ! If these schemes materialise it would have left Aston Martin as the sole surviving front-engined marque. However, the David Brown organisation has now officially confirmed its retirement from Formula One racing.

Although rear engined B.R.M.'s competed at Silverstone and Monaco early in the season, the new contender from Bourne had previously made its first public appearance during practice for the Italian Grand Prix at Monza in 1959. This prototype did not participate in the actual race, but its performance was extremely promising. It represented B.R.M.'s thoughts on the current formula and could well be regarded as a "stalking horse" for 1961.

Following the Monza trials, the new car underwent considerable development and modification during the winter of 1959-60 before making its eventual debut at Silverstone. Consequently the 1960 version has a much cleaner body shape than the Monza car. The various air scoops and cooling ducts of the latter having been discarded. Compared with its rivals, the B.R.M. has always had a short wheel-base-7 ft. 4½ in. as against the 7 ft. 7 in. of the Cooper for instance. The prototype rear engined model was even shorter by 1 in. However, due to difficulties encountered in providing adequate leg room for the driver, the wheelbase of the front engined car has now been reverted to.

At the rear the de Dion tube as used on the latter cars has been discarded because of the impossibility of finding room for it in the adoption of the rear-engine layout. A strut type of independent rear suspension, somewhat similar to that used on the 1959 Lotus car, has therefore been utilised.

Braking arrangements are by two outboard discs at the front and a single one at the rear of the transmission casing. In the tail extremity of the car it is interesting to observe that, like the Lotus the B.R.M. has a hole, in this case to assist cooling of the turbo-ventilated disc brake. This imparts to the car a somewhat bobtailed appearance.

Also of interest are the pannier fuel tanks positioned on each side of the car. They have a total capacity of 30 gallons and are of the aircraft bag type, fabricated from nitrile synthetic rubber on Terylene fabric. This type of tank will be compulsory on all Formula One cars for the 1961 season. One great advantage of this type of flexible tank is that internal baffling is not required, for as they empty they partially collapse and this in itself provides very effective baffling. Each tank is attached on the inboard side at several points to a panel bracing the top and bottom frame tubes. On the outside it is constrained to its form by the normal body panels. These twin pannier tanks on the new B.R.M. are replenished from a common filler, which connects by a Y-piece to each side, and is positioned centrally just forward of the windscreen. Between the steering linkage and the coolant and oil radiators, which are arranged in tandem, the single oil tank is mounted.

The careful repositioning of various components necessitated by the adoption of the rear-engine layout has resulted in the fact that there is little difference in the handling characteristics between this and the front-engined machine.

Many problems confront the designer of a rear-engined racing car, and to mention only one is that of overcoming the disadvantage of the much shorter exhaust pipes. The modern unsupercharged racing engine necessarily relies to a great extent on exhaust tuning for extractor effect, and such is the design of the exhaust system on the new B.R.M. that, according to reports, no power has been lost from the claimed 280 b.h.p. of the front-engined car.

Although speedy and reliable in appearance, and always full of promise, a strange jinx has seemingly hovered over the B.R.M. during past years, preventing the cars from making the grade on numerous occasions. Keen followers of the sport will undoubtedly agree that the marque is certainly and deservedly due for more victories in the very near future. In the new rear-engined B.R.M. repose the hopes of countless enthusiasts who confidently await the day when the chequered flag will signal a well-earned series of victories for the dark green cars of Bourne!

The essential prototype dimensions are: Wheelbase, 7 ft. 4½ in. Track front, 4 ft. 2½ in. Rear: 4 ft. 3 in. Overall length: 12ft. 3in. Overall height: 3 ft. 1 in. Wheel and tyre sizes: Front, 5.25-15; Rear, 7.00-15. Alternatives: Front, 5.25-16; Rear, 7.00-16, 6.50-16 and 6.50-15.

Model Maker

Bugatti Type 40

Bugatti-40 technical drawing

Prototype Parade No. 33 | Model Maker August 1951 | Drawn by Maurice J. Brett & described by G. H. Deason

Bugatti Type 40

E VEN allowing for my weakness for Bugattis generally, and the fact that we haven't had one in the series since the Type 35B in 1947, I must own that this one happened completely by chance. You should have been having a quite different car this month, and in fact everything was laid on for us to go to work on it, once more through the courtesy of Chiltern Cars of Leighton Buzzard. However, in the process of bringing our intended subject into the light of day it was necessary to push PN 4061 out into the sunshine, and I became aware of signs of ill suppressed excitement in my drafting colleague Maurice Brett, who was dancing up and down and pointing with mute appeal to the old Type 40. The old lady looked so brave in her new coat of Danube blue (and that's the nearest approach you'll get in a paint maker's sample book to Le Patron's chosen colour) that then and there we abandoned the more illustrious "car with a history", and started on the Bugatti with growing enthusiasm.

This apology is not really called for, because no member of the Molsheim family is unworthy of a place in P.P. The Type 40. however, is regarded as the humblest of the clan, and is sometimes referred to by the irreverend as the Molsheim Morris Cowley, but this is perhaps a thought unkind to a car which left the factory nearly a quarter of a century ago with 75 m.p.h. available in full touring trim. Apart from which, it makes all the appropriate noises, both mechanically and "exhaustively", and steers and stops in the traditional manner.

It was produced from 1927 until 1930, and might almost be described as a pedestrian version of the Type 37, the little four cylinder G.P. car, distinguishable instantly by its tiny radiator, which is to most people the epitome of Bugatti grace and character. The Type 40 is considerably heavier, and carries very distinctive touring bodywork and a larger radiator, but the engine is the same four cylinder 69 x 100 mm. unit, with one exhaust and two inlet valves per cylinder, operated by a single o.h. camshaft, plain bearings and the same clean, almost box like external appearance.

Unlike the Type 37 and its supercharged version the 37A, however, the four speed gearbox has a central gear lever with a central ratchet release affair, looking rather like a bicycle pump sitting up vertically in the driving compartment, flanked by a hand-brake which is plainly intended for parking rather than for grasping purposefully in elaborate moments at high speed. However, the cable-operated brakes are more than sufficient to deal with the car's performance, and operate in large ribbed drums. The chassis has not quite the same air of fragility at the front end as have the G.P. cars, although the front axle looks similar externally, and has the same curious arrangement of the half-elliptic springs passing through special lugs in the beam. The axle in this case is solid, however, and not bored out as in the case of the racing jobs. The well known reversed quarter elliptic springs are, of course, a feature of the rear end. Hartford type shock absorbers are fitted, with double friction members.

A hefty looking tubular member ties the front dumb irons, and the lamps and close-fitting helmet wings are braced by a formidable array of tubular supports. The dynamo protrudes from the crank case below the radiator, and the headlamps are the typical Marchal products of the period, with aluminium shells.

The bodywork of the Type 40 is quite unmistakeable, and in this car is entirely original, except possibly for the iron step plate which protrudes rather unexpectedly below the only door. This particular body was, I believe, known as the Type Grand Sport, and was similar to that fitted to the eight-cylinder Type 43. You either like it or you don't, according to temperament. It is a robust affair in steel, looks rather high and cumbersome, and then when the passenger carrying part finishes, it suddenly goes very Grand Sport and grows a rather comic racing tail, topped by a sort of manhole cover. This oubilette is not intended to house your mother-in-law, but gives access to a capacious compartment for luggage and tools.

The one and only door is just a square door, and the seats are definitely designed to discourage sleep, but a rather natty valance below the body simply bristles with louvres. The bonnet is rather more conservative in this direction, and boasts only a central hinge, so you keep it propped open with your head whilst you're changing plugs. The fixed windscreen has stout metal side frames, and is raked very steeply backwards.

In the driving compartment the great Ettorre's contempt for frivolity is most apparent, as it is in all his cars, and there is no nonsense whatsoever about the instrument panel. A speedometer and rev, counter you were given, also a small ammeter and oil pressure gauge, and for the rest you put your trust in Molsheim.

The steering wheel is wholly and delightfully Bugatti, with the typical unpolished wooden rim with carved fingergrips surrounding four flexible spokes which should be polished steel, but I'm afraid were painted in this case. Below the wheel a utilitarian device for ignition control looks rather like one of those gadgets the doctor uses to inspect your tonsils. The view from behind the wheel is surprising, the bonnet being, or rather looking, very short indeed. A spare wheel is strapped on the offside of the body with the traditional three-way strap, so freely imitated by small sports cars in after years.

There is also, you will note, a hood, but if it is no more use than the one which graced my Brescia Bugatti of hallowed memory it would be best to follow Maurice Brett's example and take it off! One small point worth noting is the exhaust system, which is non-standard as to its tail pipe on this car, and should be, I believe, as in our drawing.

Many specimens survive in enthusiastic owner's hands, a typical example of which I met a few weeks ago, competing in a high speed trial at Silverstone. Its owner told me that he had obtained 40 m.p.g. coming from Devonshire to the meeting, and his average speed in the "Hour Blind" was high enough to shame many modern sports cars.

The Type 40 Bugatti, whilst neither a racing car nor, strictly speaking, a sports car, is without doubt a classic example of its time, and will long be remembered with affection when many of its contemporaries are forgotten.

Model Maker

3.3L Bugatti GP

Bugatti 3.3L GP technical drawing

Prototype Parade No. 40 | Model Maker July 1952 | Drawn by H. Pratley & described by G. H. Deason

3.3L Bugatti GP

W AY back in 1946, when the first issue of Model Cars was in course of planning, a visit to Rodney Clarke at the old premises of Continental Cars at Chobham, led to an introduction to his well-known 3.3 G.P. Bugatti, and this in turn led to the series of "Prototype Parade" articles which have been continued since that date. As the first of the series, and with time at a premium, no drawing accompanied the Bugatti story, and from time to time over a space of years I have received urgent requests from enthusiasts in many countries for an authentic drawing of the last and fastest of the Grand Prix Bugattis. Recently the opportunity to acquire such a drawing arose through the courtesy of Harold Pratley, who is building one of his fine scale models of this car for an enthusiast in America, and I felt it well worth while to give a repeat of this classic car for the benefit of readers who missed issue 1 of the old journal.

Bugatti 3.3L GP cutaway drawing

The car itself well deserves this attention, for it is one of the truly classic G.P. Formula racing designs of the past, and was an extremely potent performer, despite the fact that its actual successes were not numerous. The powerful German bid for Grand Prix honours, which by the time the Bugatti was in its second year was in full swing, was sounding the death-knell of the more conventional conceptions of G.P. machinery.

All this, however, detracts in no wise from the attraction of the 3.3 as a racing car, still less as the subject for the model maker's art. Quite unmistakably Bugatti in character, it was nevertheless vastly different in many respects from the racing products of Molsheim up to that date, and is unusual in having no Type number, those confusing symbols by which the cognoscendi so confidently (and sometimes erroneously) display their knowledge of the marque. It is also worthy of note that the 3.3 was not originally a 3.3 at all as it first appeared, but a 2.8 litre car. In looking back at my original description I see that I gave the date of their initial appearance as 1934, whereas in fact two more or less experimental 2.8 litre cars were entered and ran in the 1933 Grand Prix at San Sebastian, driven by Varzi and Dreyfus, who finished fourth and sixth.

This end-of-season fixture marked the demise of the old Formula, and the introduction of the 750 kg. ruling for 1934 led to a reconsideration of engine size, as provided that the cars came under the weight limit (approximately 14½ cwt.), there was no limit to engine capacity.

Bugatti 3.3L GP painting

Our Bugatti, however, ran its first race of 1934 as a 2.8, this being at Monaco, where four cars were entered, driven by Dreyfus, Benoist and Wimille, and fourth being an independent entry by Nuvolari, Dreyfus driving into third place behind Guy Moll and Chiron in Alfas. For the French Grand Prix the engines were bored out to 72 mm., and thus became the 3.3 litres which they officially remained. Alfa Romeos continued to dominate the scene here, finishing in the first three places, but Robert Benoist wasn't far behind in fourth place. At Spa in the Belgian G.P., however, Dreyfus got home first ahead of Brivio's Alfa and Sommer's Maserati, at 86.9 m.p.h., the gallant Benoist again in fourth place. Alas, one looks in vain for another major win ; several creditable places are recorded in the lists, but the battle of the litres was proving too much for this fine motor car, which gradually dropped out of the picture so far as the Grandes Epreuves were concerned, to pass into the appreciative hands of private owners.

This "last of the classics" deserves a detailed description. A straight-eight engine of typically Bugatti design is housed in a much deeper than normal frame, having massive and lavishly drilled side members which form a notable part of the exterior "scenery". Ettore Bugatti was said to view independent suspension as the last resort of those who couldn't design a chassis, and in consequence the 3.3 retained the traditional "cart springs", albeit with the reversed quarter elliptic arrangement at the rear, but the tubular front axle, through which the half elliptic springs pass, bowed to some degree to the modern trend by having a joint in the centre to permit a limited degree of flexion. De Ram shock-absorbers damped road shocks, and the resulting chassis in some measure justified M. le Patron's faith in the old order, being a magnificent road-holder.

The twin-o.h.v. engine, with supercharger mounted on the offside, developed some 300 b.h.p., which gave the car a fine performance, though by now its rivals were outstripping it in this respect. A four-speed gearbox was used, operated by the lever shown outside the body. Brakes were cable operated, with huge and satisfying drums, and the wheels were of very special construction, possibly the 3.3's most notable external feature. These wheels had not only splined hubs but backplates integral with hub and brake drum, and carrying serrations through which the drive was taken to the rims and tyres, there being no driving load on the spokes, which are radial and numerous. I can find no official record of their number apart from my own statement that there were eighty in each wheel assembly, so presumably I conscientiously counted them at the time! These were made up of thirty-two outer ones from spoke to rim, sixteen to the inner edge of the rim and the remaining thirty-two passing through the wheel from rim to hub.

The body again represented the old order in being a two-seater, at any rate dimensionally, with the driver sitting alongside the transmission line. Slim and elegant, this is probably the most beautiful of all Bugatti's functional bodies, having lost all the previous rather barrel-like characteristics. (A remark for which T shall probably be banned from Prescott for evermore ! ) The 30-gallon fuel tank is carried in the usual position aft, and has twin fillers, one on either side of the prominent tail rib. The instrument panel is on the driver's side only, carrying a large rev. counter above the 3 in, dials of thermometer, oil and air pressure and boost gauges. The ignition lever and magneto distributor protrude through into the cockpit in time honoured fashion. I hope shortly to have the opportunity of photographing Harold Pratley's scale model of the car, which, remembering his really lovely little 2.3 litre model described a year or two ago, should be a job after my own heart.

Model Maker

Bugatti 251

Bugatti 251 technical drawing

Prototype Parade No. 106 | Model Maker March 1961 | Drawn & described by Etienne Becker

Bugatti 251

T HE presence on the race circuits of a new Bugatti F1 racing car in 1956 aroused considerable interest in the car world. This famous marque, with one of the most glorious stories in car history, had virtually ceased activities in 1939, largely due to the extensive damage to the works caused during the war.

Rekindling the torch, M. Pierre Marco, the managing director, initiated an entirely new car in 1946 with the well known Italian engineer Giachino Colombo collaborating in the designing and building of the prototype. Hopes ran high, but unfortunately it did not prove possible to follow Bugatti tradition and design for the car an entirely new engine from scratch, as had been the practice of the famous Ettore Bugatti, and the engine probably did less than justice to the car.

The principal characteristic of the car was a small tube space frame chassis which carried cooling water and also formed a motor box, the engine fitting transversely behind the seat. This gave excellent accessibility and dispensed with a transmission shaft, bevel gears, etc. The suspension was equally novel, and will be discussed later.

To the writer's knowledge, only two cars were built, the prototype which first appeared in 1955 and later in the 1956 French Grand Prix at Rheims, and a second version, basically the same, but with some minor differences. The car drawn is the prototype as it appeared at Rheims, bearing the number 28 ; of the three slightly different coachworks I have preferred to draw one which actually took part in a race. The one did not finish, the throttles jamming with dust drawn into the carburetters; the driver was Maurice Trintignant. Although it took part in only the one race, with unsatisfactory results, the originality and ingenuity of the Bugatti technique must be admired. A similar case where the car did not run was the blown 1½ litre Cisitalia, designed by Porsche; it was still a most fascinating car!

Dimensions and details of the 251 Bugatti are as follows:

  • Track, front: 4 ft. 3 in.
  • Track, rear: 4 ft. 2 in.
  • Wheelbase: 7 ft. 2½ in.
  • Overall length: 12 ft. 9 in.
  • Maximum width: 4ft. 5½ in.
  • Maximum height: 3 ft. 5½ in.

Engine

Eight-cylinder in-line. 76 mm. bore, 68.5 mm. stroke, 280 h.p. at 9,000 r.p.m.

The engine consisted of two 4-cylinder units mounted back to back, each unit having its own crankcase and block, surmounted by twin overhead cam-shafts and covers. The gear train between the two units drove through another spur gear the multiple-disc clutch and gearbox, which are built in with the differential, this whole assembly bolting to the side of the engine. Five forward gears and reverse were fitted. Four Weber carburettors and two Marelli magnetos supplied mixture and spark respectively. The first engine built was not highly tuned in order to allow thorough testing of chassis, etc.; racing versions tuned for alcohol and with racing camshafts, etc., were then built.

Suspension

Both front and rear suspension were non-independent, using de Dion type tubes located by double radius rods and centre guides. Rocking links operated rods compressing springs inside long tubes attached to the opposite sides of the chassis. Telescopic shock absorbers were installed. Front wheels pivoted on the ends of a single cross-tube between hubs. This unusual arrangement was never thoroughly developed and tested, but Trintignant had handling trouble, particularly with snaking on fast bends. with both cars on their only appearance.

Disc brakes were fitted to the first car, but the second had two leading-shoe drums fitted at the back.

Radiators for both oil and water were sited at the front, and the fuel tanks were in the body sides each side of the cockpit.

The positioning of the motor and the side-mounted tanks produced a compact, rather bulbous body, and it was possible to use a relatively short wheel-base; this probably had much to do with the handling difficulties, but the second car, which was lengthened slightly, still suffered from trouble in this respect. Lack of resources doomed any development programme, and the Bugatti 251 therefore remains an interesting and ingenious vehicle which left many of its queries unanswered.