ALL EYES ON "BLUE BIRD"

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48

ALL EYES ON “BLUE BIRD”

THE GIGANTIC CAR WITH WHICH SIR MALCOLM CAMPBELL IS TO MAKE AN ATTEMPT TO REACH THE COLOSSAL LAND SPEED OF 300 M.P.H. CLOSE ATTENTION TO DETAIL WORK SHOWS THE IMMENSE AMOUNT OF PREPARATION REQUIRED.

THE mere man in the sports car, so to speak, can only stand in silent wonder before the impressive appearance of” Blue Bird,” and his admiration extends to the intrepid man who has already held the world’s flying mile and kilometre records on more occasions than anyone else.

When ” Blue Bird ” was pushed out Of Sir Malcolm Campbell’s private shed in the Brooklands Paddock on a foggy day in January, it presented a very different exterior from the car which set up the existing record of 272 m.p.h. two years ago. The chief alteration lies in bringing out the sides of the body to the full width of the car, so that the wheels are now completely inset. The ” nose ” has been correspondingly widened, and the result is a complete transformation. The tail, too, has received attention, and the total effect is a really magnificent example of advanced streamlining.

Prom End to End.

Let us examine the car, from end to end. The huge nose consists of a Serck radiator, the header tank of which is situated over the front axle. The air intake is in the form of a narrow aperture, and it is in connection with this intake that We come to the first of ” Blue Bird’s ” many ingenious features. A good deal of windage is naturally formed by the aperture, and in order to give the car every chance to attain its maximum speed, Mechanism has been provided whereby Sir Malcolm can close a sliding -flap over the intake. He will, of course, resort to this action only when the car is about to enter the measured mile, so that the radiator is deprived of its cooling air-stream for the shortest possible time. On the last visit to Daytona the mile was covered in 13.23 seconds, not long enough for any damage to be done by overheating. The flap is operated by means of an Arens control and a spring-loaded lever is placed to the right of the cockpit. It is essential _ that the process should be a quick and

easy one, for the driver’s hands should not leave the wheel for longer than is absolutely necessary.

Ahead of the engine, and projecting through the body proper, is the air scoop leading to the supercharger. This intake curves down below the header tank, behind which we Come to the massive Rolls-Royce 12-cylinder engine. The two banks of overhead camshafts are the highest points of the car ahead of the cockpit, and the bonnet fits over them with only a very small clearance, thus forming the two ridges between which the driver has his forward vision. The drive of the 2,350 h.p. engine is taken to the 3-speed gearbox by means of a multiplate clutch, and thence to a doubledrive rear axle of a most ingenious layout. The propeller shaft carries two bevel wheels. The first one drives the righthand road wheels, while the second is placed so that it just clears the teeth of the right-hand half-shaft bevel. Instead, it Connects with the bevel of the left-hand half-shaft. This arrangement results in the rear-wheels being offset to the extent of l inches, an altogether unusual departure.

Behind the cockpit is situated the colossal suction cylinder which Operates the air-brakes. The tail itself consists of a light steel tube framework, smoothly panelled. Such is the rough layout of ‘ Blue Bird.” Now let us turn our attention to details.

Power !

The Rolls-Royce engine is exactly the same as that used in the victorious Schneider Trophy seaplanes. It is a Vee 12, with a bore and stroke of 156.4 mm. and 167.64 mm. respectively, giving a total cubic capacity of 36,582 c.c. On the basis of the R.A.C. rating the horse-power is 173.28 h.p.. and it is calculated that at 300 m.p.h. the engine

would be turning over at 3200, r.p.m., and giving an output of 2,350 h.p. This concentrated power plant weighs 1,630 lbs.

The stubby exhaust pipes, six each side, emerge direct through ports in the bonnet.

The chassis frame, like every component of the car, has been designed to give a wide margin of safety even under the abnormal conditions in which it has to function. Accordingly, it is of exceptionally massive construction and of great depth. It is upswept over the front axle, but dips under the rear axle, which is underslung. Attached to the side members at various points is the framework of steel-tubing which carries the panelling of the body to the full width of the car. The space between the front and rear wheels, outside the chassis frame, is occupied by a 40gallon petrol tank, the fuel being delivered to the engine by means of Petroflex tubing. Incidentally, a special consignment of Pratts fuel has already been shipped to Daytona from London.

The front axle is a new design. It consists of a circular forging, and is attached to the semi-elliptic springs by means of bronze bearings which, in turn, are carried in housings on the springs. Thus the front axle is fully floating, and the risk of brake reactions twisting the springs is completely eliminated. The axle itself is anchored by a. Vee-shaped girder, pivoted at the apex to the axle and attached at each end to radius rods leading to a special cross member.

The springs, both front and rear, are of Woodhead pattern, and are assisted by a veritable battery of Andre-Silentbloe . frictional shock absorbers, six in front and four at the rear. With the object of combating excessive axle movements two of the front shock absorbers are outrigged. The rear axle is attached to the springs in the same way as is the front, and in order to limit the amount of frame movement strong hoops are used in conjunction with rubber buffers attached to the axle itself.

Steering Stability.

In an attempt of this sort every part of the car plays a vital part, but certainly

no component is more important than the steering gear. On its last run, it will be remembered, “Blue Bird” was fitted with a duplicated steering gear, but this has now been abandoned. In its place we find an orthodox layout of drag link and track rod. A Burman-Douglas steering box is mounted on the chassis frame, and is connected to the Bluemel flexible steering wheel by way of a miniature Hardy-Spicer tubular propeller shaft. The driver sits in a very low position, thanks to an offset transmission, obtained by taking the final drive off the lay shaft, and this necessitates an exceptional slant in the steering column. This is overcome by the use of a Hardy-Spicer universal joint next to the steering-box. The other end of the column is carried in a stout bearing just ahead of the dashboard.

No step must be left undone in designing a car to attain such a colossal speed, and the precaution has been taken of fitting two Titan steering stabilizers on the front axle. These interesting devices work on the inertia system, two small weighted flywheels being contained in circular boxes, and working in oil. Their outstanding merit is that they ensure steering stability without the stiffening in operation which results from the usual pattern.

Sir Malcolm’s chief difficulty lies in the all-important question of acceleration and braking. The former is limited by the numerous small shells, with knife-like edges, which unfortunately abound at Daytona. The tyre treads are of necessity extremely thin, not more than 1 /16th inch, because a greater thickness would be torn off by centrifugal force. If too much wheelspin is experienced in an effort to make as much use of the available distance as possible, the result might easily be a punctured tyre—an eventuality to be avoided at all costs. This year twin rear wheels are being used, giving greater wheel-grip and less tyre wear. The wheels are covered with Ace discs to assist streamlining.

Wonderful Tyres.

The importance of tyres in this record attempt is paramount, and it is not too much to say that without the special Dunlop tyres the existing record would have been impossible. The greatest possible credit is due to the Dunlop research department in the production of accessories on which the driver depends for his very life.

Now we come to braking. The ideal distance for the record attempt would be 14 miles, for the great car takes seven miles to get into its fastest gait. The acceleration stretch of sand has been improved this year by removing one of the supports of the pier, beneath which the car has to pass. But Sir Malcolm is still left with only three miles in which to pull up his flying steed.

Obviously, heavy pressure on the brake pedal, while the car is travelling at 300 m.p.h. is likely to result in the most untoward eventualities — even though Ferodo brake linings are, of course, being used. You must remember that the car is no normal vehicle in weight, for it scales five tons, including its lead ballast !

For the initial checking of speed, the car is equipped with air brakes in the form of hinged flaps just behind the rear wheels. Once again a servo-system has been brought into play to assist the driver in his difficult battle with wind resistance. The considerable strength required to raise the flaps to a vertical position is derived from a huge Clayton-Dewandre vacuum cylinder carried in the tail. The piston-rod of the cylinder works the flaps by means of a chain and lever on a massive cross-member. Thus the driver, will be able to apply a gentle pressure to the brake pedal and the flaps will promptly rise to the vertical. The remainder of the pedal movement is taken in the ordinary way by the servo mechanism of the wheel brake. The latter consist of aluminium shoes with Ferodo linings in great ribbed drums on each wheel. The operation is carried out by cables.

The process of slowing a rapidly moving car is always a tricky one, for the car is deprived of the steadying effect of the engine driving the rear wheels. In the case of ” Blue Bird,” however, the airflaps will make up for the loss of this effect. Like the elevators of an aeroplane, they will tend to force the tail of the machine downwards, thereby giving the rear wheels a firm grip on the sand.

Normal Controls.

The cockpit of the car is protected from wind pressure by a stoutly constructed sloping widscreen. The driver sits in a normal bucket seat. Facing him are the Smith instruments, and dwarfing all others is the. large rev-counter. One cannot imagine the driver being able to find much time to glance at the rest of the instruments, but they will serve their purpose when the car comes to rest at the end of each run. They consist of a watertemperature gauge, supercharger pressure, oil temperature and pressure, and petrol gauge. The controls consist of thc usual clutch,

brake and accelerator pedals, the latter being tucked away on the inside of the chassis frame. In addition there is a petrol cock, .the lever which closes the air stream slots in the nose, a hand throttle for the engine, and a screw-down valve which cuts out the wind-flaps should they not be required.

” Blue Bird ” is a masterpiece. All those who have had a hand in its design and construction are to be heartily congratulated on a production—nay, a creation—which reflects the greatest possible credit on British engineering skill. Mr. Reid A. Railton has *designed many fine cars in his short career ; certainly he has never designed, a more impressive one than ” Blue Bird.” The same can be said for the firm which has built the car from his designs, Messrs. Thomson & Taylor, of Brooklands. As for Sir Malcolm Campbell, we can

only join in the general good wishes of all British sportsmen for his complete success in an epic adventure. No man is better equipped for the task, for he has already confirmed many times Over his reputation as a driver of skill, determination and courage. May good luck attend him l

The Components.

Here is the full list of components and accessories used in the construction of “Blue Bird.” Every one is of vital importance to the success of the venture, and the mere fact of their being used places a” hall-mark “on them : —Dunlop wheels and tyres, Ace discs, Tyzack clutch plates with Ferodo linings, Hoffman bearings, K.L.G. sparking plugs, E.N.V. back axle gears, D.D.S. gearbox gears, Moseley Float,on-Air upholstery, Hadfield front axle and rear axle forgings, shafts, etc., •Castrol oil, Guest Keen and Nettlefold’s bolts and nuts, B.T.H. magnetos, chassis frame by John Thompson Motor Pressings, Ltd., Pratts Ethyl fuel, Pyrene fire-fighting equipment.

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