THE ” NAPIER CAMPBELL” RACING CAR. Details of Capt. Malcolm Campbell’s 450 h.p. New Chassis.
A T the time of writing preparations are being made for the attempt to accomplish a speed of
180 miles an hour and the following description gives the principal details of the huge Napier-Lion engined car, upon which Capt. Campbell has been engaged for a long time. We recently had the opportunity of inspecting the machine whilst the final preparations were in progress at Capt. Campbell’s private workshop and made a close examination of all the details. A mere description, however, cannot adequately convey the wonderful degree of workmanship that is to be seen at all points on the chassis, for though the components are naturally
of immense strength, a factor of safety of 7 to 1 prevailing throughout, this does not prevent an exquisite finish to the mechanical parts, which is such that is seldom seen in any form of car.
The Napier Campbell is not merely a chassis provided to carry a huge aero engine, as has been the case when giant cars have been produced hitherto, but is designed with the greatest originality, backed by Capt. Campbell’s personal experience of the special requirements for running at the terrific speeds which it is hoped to attain. Mr. Joseph Mania is responsible for the greater part of the design and the car was built at the premises of The Robinhood Engineering Works, where the K.L.G. sparking plugs are made. Most of the components have been built to special order and some idea of the amount of work involved in their manufacture can be
judged from the fact that everything has been machined out of the solid, with the possible exception of the accelerator pedal, which is made from a valve stamping. The chassis is enormously strong and was made by hand at the Don River Works of Messrs. Vickers, Ltd., three per cent. nickel steel being used throughout. The side members are exceptionally deep and the four enormous tubular cross members are machine forgings. As very little ground clearance is required on this car, the frame is very low, extra stability being provided by the method of slinging the frame under the rear axle. From an inspection of the frame it appears inconceivable that any whip or distortion of the frame could possibly
occur, but as Capt. Campbell pointed out, nobody knows yet what may happen, as soon as this leviathan begins to move at its maximum speed. At all events, every possible precaution has been taken to achieve the desired object and although many unconventional features of design have been incorporated, there is little of a really experimental nature to be seen.
The engine is a Napier-Lion direct drive aero engine, with twelve cylinders arranged in three blocks of four, the centre block being vertical and the two others disposed at an angle of 60 degrees. The R.A.C. rating of the engine is 145.5 h.p., but at 2,000 revolutions per minute 450 h.p. is available and when the speed is increased to 2,200, the power developed is 502 h.p., thus
compared with ordinary racing car engines, this one may be considered as having a low speed.
As the whole engine weighs 915 lbs., the weight per horse-power is only 1.83 lbs., which gives some idea of the wonderful efficiency of the modern aero engine. The engine lay-out also, provides this enormous power in a comparatively limited space and the projecting cylinders do not, as might at first be supposed, interfere greatly with the stream-lining of the car as a whole. Two twelve cylinder magnetos are used, these being driven by a cross shaft at the front of the engine, and two K.L.G. plugs are fitted to each cylinder.
The clutch is of the multiple dry disc type with sixteen Ferodo lined surfaces 111in. in diameter and to ensure a free engine with the epicyclic gearbox used, an additional hand lever is provided at the left hand side of the driver, as well as the ordinary form of clutch withdrawal mechanism. The clutch is incorporated with the flywheel in the ordinary way and the driven member is formed by the casing of the clutch, upon which is mounted a metallic flexible joint of 13iin. in diameter.
A large spherical joint is situated immediately at the rear of the clutch, which carried by one of the four cross members of the frame, supports the forward end of the gearbox. The latter is one of the very special features of the car and is the joint invention of Mr. W. S. Foster Brown and Mr. Joseph Mania. The gear box provides three forward speeds and one reverse, the ratios being as follows :—First speed, 1 to .333, second 1 to .666 and 1 to 1 for top gear, the ratio of the final drive being 1.27 to 1.
In the usual form of epicyclic gear, frictional breaking surfaces have to be used for holding the various drums in order to bring the satellite pinions into operation, but in this case a special patented device is adopted, whereby the power is transmitted without the slightest friction. This we were able to judge by removing one of the small covers on the gear box and by turning one of the pinions, the whole car could be moved backwards or forwards by the effort of the hand alone. The gear box, which is a very substantial piece of work,
was built by Messrs. Beard and Fitch and is fitted with roller bearings throlighout. A novel system of conical friction wheels has been inroduced, by which small pinions on the lay-shaft are slowed up or slowed down, in order to relieve the satellite carriers of all shock whilst they are being brought to rest. The whole gear box forms an integral unit with the rear axle and is carried on the forward end of the torque tube.
The design of the rear axle includes a method of supporting the crown and bevel independently of the axle casing, so that any possible distortion of the latter will leave the gearing unaffected. Reinecker bevels are used for the final drive and the axle shafts are fully floating. At either side of the axle casing are two conical extensions, machined from solid forgings, which carry the weight of the car and at the ends of these are carried the rear wheel bearings. Triangulated torque rods fitted between the spring blocks and the rear of the gearbox, give additional bracing to the unit as a whole.
Built in two pieces and joined in the middle by substantial flanges, the front axle has a laminated torque member, extending forwards to a round cross member fixed between the front dumb irons, the idea of this arrangement . being to relieve the front springs of all torsional stresses.
The whole of the steering gear is duplicated throughout and a considerable amount of work was necessary to synchronise all the movements to give the necessary degree of accuracy. A flexible spoke steering wheel is used and the bevel gearing at the bottom of the column has a cross shaft extending right across the frame and at each end of this cross shaft is a Marles steering gear operating the two drop arms. Thus by the use of two steering drag links, each front wheel is directly controlled, but this lay-out does not interfere with the application of the ordinary Ackermann principle of steering.
Four duplex shock absorbers of the Hartford type are used in conjunction with the front axle suspension, their upper ends being secured to a special cross member the front axle.
THE ” NAPIER-CAMPBELL ” RACING CAR
Semi-elliptic springs of the Woodhead self-shock absorber type are used for the suspension of both axles, those at the rear beinc, 4ft. 21in. long and those at the front 3ft. lin. long. Manganese spring blocks are used to anchor the springs to the axles by the aid of a double set of ” U ” clamp bolts.
Owing to the small width of the large diameter brake drums it would have been difficult to airange the brake cams well within the centre line of the steering, but by the use of a special form of cam designed by Mr. Mania, this has been accomplished, which renders the action of the brakes and the ease of steering perfect in all respects. The brakes operate on Alford & Alder principle and can be used. direct, or by means of a Clayton-Dewandre vacuum servo mechanism.
In order to obtain the best streamlining, the radiator is relatively small, therefore the header tank of 10 gallons capacity, is mounted over the steering column ; the petrol and oil tanks occupy a position at the rear of the frame and are covered by the tail of the body.
The body of the Napier-Campbell, though providing little room to spare for the driver, is a wonderful piece of work and has been designed in accordance with airship practice, all the lines being carefully calculated to give the least possible wind resistance at the colossal speeds that are anticipated.
The Thompson Cup Trial.
From the nature of the course, it is not surprising that car owners held more or less aloof from the Thompson Cup Trial, which was held in the Camberley district last month. The first hill was on Barossa Common, near the Camberley Golf links, some 200 yards from the start. Here the incline and surface was well up to Camberley stan dard and C. V. Patrick was seen to make a very good climb, the performance of Miss E. Sturt on another Scott
being equally meritorious. An excess of caution appeared to prevent H. W. Bostock from getting up and his Triumph skidded badly, causing the rider to come to earth. One of the best climbs was made by E. C. Lunnis on a Raleigh combination. A greasy patch some three mile further on caused a great deal of trouble among the competitors and two
machines had to be withdrawn owing to gearbox failures. Two rather exciting incidents were witnessed, the first being when V. L. Freeman overturned with his
Matchless sidecar, following a puncture and the second was during the second round, L. C. Bailey travelling towards White Hill at a terrific speed on his Norton, left the track and took to the heath. By a good piece of riding, however, he managed to regain the course and actually completed the climb without stopping or using his feet.
C. V. Patrick won the Thompson Cup, the Lunnis Cup being awarded to B. W. Swabey (James) and the Burlington Cup to T. G. Meeton (Francis Barnett).