ON STREAMLINED FORM
ON STREAMLINED FORM (Continued from the April Issue)
PART III, RECORD-BREAKING CARS
OBVIOUSLY, streamline reaches its greatest importance when a car is planned solely to achieve the highest speed possible over a straight course for a given size of engine—cars built to travel faster than any cars have previously travelled, which we all refer to as ” Land Speed Record” cars, though this definition is a rather loose one, are covered by this statement, inasmuch as their engine power is still limited by the engines available, if not by actual cubic capacity. The question naturally arises, is there any limit to speed of a man-made nature ?—already a boat has reached 1291 m.p.h., an aeroplane almost 464 m.p.h. and a motor-car 3571 m.p.h., propelled in every case by an i.e. engine. Last month 700 m.p.h. was quoted as the possible velocity at which vehicles will have to give best to air-resistancethe speed of sound waves ; not of light rays as was incorrectly stated. Lots of People seem to think that this figure Of approximately 700 m.p.h, is merely a convenient speed to visualise, just as 150 mph. was a nice sound figure to aim at when cars had just exceeded 100 m.p.h., and 200 m.p.h., or 180 m.p.h. as representing three-miles-a-minute, the round figure next in mind when Sir Malcolm had exceeded 150 m.p.h., though having no technical significance of any kind. Actually, the reason 700 m.p.h. is quoted as the possible top limit to man-made speed is because this is the maximum speed of sound-waves, which the scientist believes to be checked by self-made al) -resistance, which as we know, increases as the square of the speed, and has obviously a greater retarding effect on sound waves than have more tangible mediums. CerUtinly aircraft can child) to a rarified atmosphere but a vicious circle phere is then entered, because the power of the engine falls or, if maintained by supercharging, the blower absorbs lunch power which should la* applied to the air screw, apart from the problem of getting the ,machine, with wings that will support it in thin atmosphere and a highly boosted engine, up to operative heights. Actually, on this subject, Dr. NV. E. Hilton, of the Aerodynamical department of the National Physical Laboratory, lecturing recently to the Royal Aeronautical Society, expressed the opinion that aircraft Would reach their limit at 550-600 m.p.h. unless retractable wings. were used. He thought that a car might reach 700 m.p.h. with 4,000-5,000 h.p. and suggested a body twice as high as it was wide, of three to four times as long as it was wide, and with a completely semi-circular front. So, although the land speed record is over 100 m.p.h. behind the air-speed record, it may one day go ahead. Although we are now only concerned with streamlining, it is interesting to note that it is only very recently that four-wheel-drive and enclosed cockpits have been used for attacks on the fastest-car records of all, and that .very high speeds were realised with comparatively old-fashioned chassis-designs. Other questions having a close bearing on the ultimate limit to Vehicle speed are the relation of air-screw tractiveeffort in relation to -a wheel’s adhesion factor, and the fact that while float-aircraft can land more safely at high speeds on unprepared ” ground ” than a land aircraft, and have more available radiator surface area, the drag of the floats imposes severe limitationthe seaplane record is up to 440 m.p.h., but with some 1,000 h.p. in excess of that used in establishing the existing absolute speed record of 4444 mph. with a land p la ne M a y be future attackers will be launched by catapult, discard the wings and, heading the machine out to sea, will attempt to jump clear after doing the timed flight ltlaterial, there, for the penny dreadfuls. Actually, to return to the
present, and the subject of this article, the speed-of-sound-limit theory is rather .shattered by the fact that shellstired from a high velocity 25 pounder field gun are estimated to exceed 900 m.p.h. It remains to be seen whether at such speeds the temperature raised by skinfriction would destroy the cooling properties of the radiators, if it did not damage, or set fire, to the structure. Coming to a consideration of what has been done up to now, serious streamlining for Land Speed Record work commenced in 1924, when. Capt. (now • Sir) Malcolm Campbell prepared the V12 Sunbeam for an attempt to reach 150 m.p.h. In those days we all thought the long tail, faired hand-brake, and casings round the rear brake drums, the last word and the car was duly accorded a front cover position in MOTOR SPORT. The Sunbeam did 150 m.p.h. on some 400 h.p., which any good road-racing car does as a matter Of course these days—Billy Cotton, who bought the Sunbeam for fun some ,years ago, cannot find his 11.-litre E.R.A. so very much slower. Actually, away back in 1903 an intended-record-holding Baker Electric—of which breed an example was entered for the Veteran C.C. Tilburstow Hill-Climb last month— appeared with cigar body and a real enclosed cockpit with, if I recollect correctly, a 3 inch mica windscreen and a sort of conning-tower hatch held down by wing-nuts—which damaged the drivers’ head when a policeman dropped it trying to open things up after a rear wheel had pulled off at speed. Returning to post-war times the next important Land Speed Record .car was the popularly-called 33 11.1). Sunbeam—the 4-litre V12 ” Ladybird ” with which the late Major (afterwards Sir) H. 0. D. Segrave did 132 m.p.h. on Southport sands in 926. The remarkable thing about this car from the streamline point of view was that it had more or less a ” Fiat-form.” G.P. body, albeit the bulges concealing the cylinder heads, the dumb-iron cowling, and the Eldridge cowl were evolved in their final form only after coloured smoke
tests in the wind-tunnel. When Sir Malcolm bought the car and had it modified, to win the first Mountain Championship, much of this form was lost. The Sunbeam developed 306 b.h.p., and weighed 18 cwt., so you see how streamlining has assisted speed even giving the 248 m.p.h. 3-litre ‘Mercedes-Benz the discredit of a rather greater power output. At this period Sir Malcolm Campbell was busy with the first of his really specialised ‘` Bluebirds.’ The Body
was high, but was kept narrow by Careful fairing in of the V12 Napier motor, back-staggered Eldridge-type radiator cowl was used, small parts were carefully faired, and a rather elaborate threepiece box-screen, as was later used on all the cockpits of the Land Speed Record cars. We all marvelled at this car in 1927, when it did 174.8 m.p.h. at Pen dine on 450-500 b.h.p. Parry Thomas, who held the record at speeds around 170 nap.h, with an engine variously reputed to give 400-600 b.h.p., was, we know, working with ancient material, but he nevertheless contrived to give ” Babs ” a reasonable form, using a Leyland-type front cowling, using a sort of narrow sub-bonnet above the main bonnet to accommodate the valve cover of the Liberty motor, and a long, tapering tail. Later he faired in the rear axle and driving chains with long, pear-shaped cowlings. This was the last normal racing-type car to achieve these ultrahigh speeds. Perhaps we may accordingly digress to ask if anyone can explain why the simple form of radiator cowl, used on each successive car but not on Thomas’s machine, is called an” Eldridge cowl “—it was used years before the late Ernest Eldridge started to race and, so far as we know, his Isotta-Fraschini and later Isotta Maybach (built, by the way, at No. 31, Vauxhall Bridge Road) had untowled radiators, while this F.L A.T. had an elaborated sort of cowl and his 11-litre Eldridge-Special a quite different cowling, rather like the forerunner of the frOntwork treatment of present G.P. cars. We rather believe a motortrader used the expression to describe the cowl on a sports Amilcar, because Eldridge owned one of these cars, but can anyone confirm this ? Two hundred m.p.h. now became the aim and the Sunbeam Motor Co., Ltd., always keenly interested in competition work, built the revolutionary twin-engined, chain-driven 1,000 h.p. Sunbeam to attempt this speed. This car had a length of 23 ft. 6 in. and the body was a beetle-shell extending out over the wheels, fiat-topped with bevelled edges merging into the vertical side panels. An aperture in the nose admitted cooling air and a headrest and screen-cowl were used. The rear exhaust stubs were unfaired and discs were used
only on the rear wheels. The result was 203.7 m.p.h. at Daytona. Next, Sir Malcolm had another crack. This time a boat-shape body was used, not so narrow as before, and the nose of the new ” Bluebird” was unbroken by a radiator aperture, because an aircraft-type tube-cooling: element was
carried on either side of the tail. A stabilising tail was used and the wheels, uncovered, had streamline tails behind them. With the Napier motor rather more boosted, a speed of 206.9 m.p.h. was attained.
Immediately after this Keech pushed Things up to 2071 m.p.h. with the -totally unstreamlined White Triplex—but he needed three motors and unlimited power to do it. The next venture into the realm of ultra high speed was Capt. Irving’s famous ” Golden Arrow,” probably one of the prettiest giants ever seen. A kind of two-section body was used, the ” bonnet” being a snug cowling round the Napier broad-arrow aero engine, the centresection covering the vertical block and providing the forward and aft cowling around the cockpit, which had a moderntype box-screen and shoulder-high sides. The tapered tail ended in a small, square fin and the cooling element took the form of tanks between the wheels, thus assisting streamlining of them, while leaving
the nose clear. Segrave got this car up to 231.4 m.p.h. and it must have owed much to Schneider Trophy influence. Here we must mention the remarkable little 3-litre Stutz, which never held the record, and which eventually killed its driver, but which reasonably reliable accounts saydid 200 m.p.h. It had a cigar-body, the wheels enclosed in separate “spats,” and the radiator set
as a saddle -across the bonnet. It was only 48 m.p.h. slower than the modern 3-litre Mercedes-Benz record-breaker and so interesting that we described it rather fully in a special article less than three years ago. Sir Malcolm replied to Irving with further modifications, Made by Reid Railton, to his ” Bluebird.” The aircrafttype radiator was thought to be unsuitable, so a normal radiator was isolated in a separate, streamlined nose, behind which was a faired body. A lower bonnet line was achieved by bringing the cowling close round the engine— still a Napier (but supercharged, of 1,450 h.p.)—the wheels retained the faired tails and leading edges for the rear pair and the tail had a big fin. A speed of 264 m.p.h. was realised at Verneuk Pan with -a form agreed rather makeshift. In 1930 appeared the CO atalen-designed Sunbeam ” Silver Bullet,” with two specially-built engines, A cross between the beetle and cigarshape was used and the radiator problem was completely overcome by employing internal ice-chests for cooling purposes, probably the first time this had been done. Skin-friction was reduced by making the car narrow and resisting any temptation
to enclose or fair-in the wheels. Kaye Don never got the expected speed from the car and Dixon bought it some time ago but apparently has scrapped it. It was rumoured that this design resulted in a considerable rift between Coatalen and Sunbeams—Coatalen is to-day designing. very good c.i. aero motors. Campbell’s next run was with the engine still further boosted, resulting in 253.9 m.p.h. For his next attempt he used a Rolls-Royce ” R ” type motor of
some 2.300 h.p. The Gurney Nutting body of ” Bluebird ” remained much as before, but the bonnet was cowled close to the much bigger engine. Schneider seaplane fashion, the radiator, though still isolated, was cowled into the body at the top, and, in spite of drag, the blowers air intake was carried higher than before, clear of flying sand and spray—its aperture was such that at full speed air pressure accounted for an additional manifold boost of 2 lb. per square inch ; recalling Parry Thomas’s air-scoop on the Leyland in 1923 or ’24. In this form ” Bluebird ” motored over the kilometre at 272.4 m.p.h. For a further attempt, two years later, very sweeping changes were made. The body was now extended the full width of the car and given a long cowling between the wheels, doing away with the separate fairings used formerly, and functioning as did the ccoling tanks on the ” Golden Arrow.” The radiator—ever a problem—was no longer isolated, but the nose tapered on a horizontal plane to a narrow strip the width of the body, and the air duct therein was provided. with a flap which the driver could close by means of a hand control when the car was running in the timing zone. The cylinder blocks were cowled Schneider fashion and the supercharger intake set low in the forward part of the bonnet. The exhaust stubs were flush with the bonnet top, the tail still carried a fin, and the cockpit used a rather wide, box-type screen. The wheels were tuaenclosed at the sides, and just protruded. above the fairings ; they carried Ace discs. Servo-operated air-flap-brakes. were fitted behind the rear wheels. Railton again looked after the design
and the engine gave 2,350 b.h.p. The car first took the record at 276.8 m.p.h. and later raised it to 301.1 m.p.h.thus realising Sir Malcolm’s ambition to exceed 300 m.p.h. in a car, before resting on his Land Speed laurels.
As to the present ears, Eyston’s. ” Thunderbolt” and Cobb’s Railton are very differing types, both, however, having body shells that extend out and. completely enclose the wheels without any fancy fairings around either engines or wheels. Eyston first used a not entirely enclosed cockpit but eventually went over to it, and Cobb sat in total enclose at 345 m.p.h.—Eyston, of course, has the record up to 357 m.p.h. Both cars have blunt noses and flat, beetle bodies, and the Railton has the cockpit protrusion actually forward, ahead of
the front axle. Eyston formerly used_ a forward radiator, but last year he scrapped this and put on an airship shape nose-cowl, using ice-tank cooling, and the Railton also uses ice-cooling to eliminate radiator drag. It is interesting that this method of cooling, introduced eight years earlier for the ill-fated ” Silver Bullet” is used on both the present cars.
After considering how such great speeds are attained, almost entirely by correct streamlining, it is interesting to observe that such speed is killed in Eyston’s case very successfully by air-brakes, which show improvement over former attempts to use such components—aided, of course, by the excellence of Ferodo on brakes of more normal aspect. There is just space left in which to observe that in other record-breaking spheres the trend is to extend the body out to enclose the wheels, or to give them very considerable fairings of their own, and to close-in the driver very extensively, though not always by roofing
the cockpit. Austin reached 94 m.p.h. and M.G. over 100 m.p.h. with quite ordinary raeina bodywork, but the first 100 m.p.h. A ustins had an isolated radiator, and fairings between its wheels like those on the last ” Blvebird,” and from then onwards sprint record cars of all capacities have taken more and more leaves from the lesson-book of ” Land Speed Record ” streamline form.