MOTORING WORLD.

Manawatu Standard, Volume XLVII, Issue 124, 23 April 1927, Page 14

MOTORING WORLD.

HIGH SPEED PHENOMENA. STRIKING FIGURES. ' Some striking :igurea recently given by The Motor, England, in reference to wind resistance and other high speed phenomena are now most interesting, since Ihe world’s record of 203 miles an hour has been established by Major Segrate with a 1000 h.p. racing car. It is calculated that wind resistance of a car moving through the air increases approximately in proportion to the square of the speed; the power needed to drive a car against this resistance, • however, depends not only upon the prsasure of the air upon the car, but is also proportional to the rate at which the car is travelling. The power heeded at the rear wheels varies in proportion to the cube of the speed, i.e., if 10 h.p. is needed at 50 m.p.h., then at double the speed —IOO m.p.h.—the power must'be eight times as great, so that 80 h.p. will be necessary to overcome wind resistance alone. It follows that 640 h.p. would be needed to propel the same car at 200 m.p.h. In. round figures a flat surface with an area of 16 square, feet requires only 1 h.p. to propel it through the air at 20 m.p.li., whereas at 200 m.p.h. no less than 1000 h.p. is necessary.

In a car built specially, for racing purposes the frontal area is reduced to a minimum and the body is streamlined so far as possible, ■ the aim _ in each case being to reduce wind resistance to a minimum. It is said that in the case of Major Seagrave’s car, 355 h.p. is needed to overcome wind resists ance at 20 m.p.h., a figuie which would appear to show that by careful streamlining the equivalent frontal area for this car is only about 4} square feet. The figures given refer to the power actually needed at the rear wheels to overcome wind resistance alone, to which must be added the power to overcome rolling resistance, which, although small compared with the former, is by no means negligible. Having arrived at the total the designer must make allowance for the losses which occur in transmitting the drive from the flywheel to the rear wheels; thus, if the mechanical efficiency of the transmission is 80 per cent, and the rear-wheel power is 800 h.p., the engine must actually develop at least 1000 h.p. One of the problems to be faced is to arrange for sufficient adhesion between tho tyres and the track to permit of the transmission of power without wheel spin. When the rear tyres are transmitting a total of 800 h.p. at a speed of 200 m.p.li. each of the treads is kicking back against the ground with a force of about 7501 b., and , consequently, in order to ensure that wheel spin shall not occur, the downward load on each must be about double this figure. Consequently., a back axle weight of about li tons is needed. At 200 m.p.h. a 30 inch pneumatic tyre must revolve at about 2250 r.p.m. At this speed each ounce if rubber in the tread is pulling outwards with a centrifugal force of 135 lb. and delicate balancing of the wheels is obviously an essential. _ Even with the phenomenal acceleration of which it is capable, a car built for’short-dis-tance record breaking requires a considerable distance in which to reach its maximum speed before crossing the timing strip. Some idea of this may be obtained from the fact that, where the car to fall vertically, by gravity, then neglecting wind resistance, it would drop through one-quarter of a mile before reaching 200 m.p.h. .The 1 braking distances of an ultra-high-speed car are interesting. Really good four-wheel brakes will stop an ordinary car from a speed of 50 m.p.h. in a distance of about 105 ft. and if we take this distance as being proportional to tho square of the speed a pulling up distance of 1380 feet can be deduced as being necessary at 200 m.p.h. The driver has the advantage over the aeroplane pilot of travelling in a straight course when travelling at a rate which ea :s up distance to the tune of 300 feet per second. He must be protected against wind resistance; if

his head, were fully exposed at 200 m.p.h., it would be subjected to air pressure totalling nearly 1 cwt. ENGINE LUBRICATION. WONDERFUL EXPERIMENTAL WORK. Much has been written and talked about engine lubrication—probably the most important matter concerning the running and the maintenance of the motor car. And during the last ten years a wonderful amount of serious experimental work and research has been given to this matter, so that today we seldom hear of engine failures or engine inefficiency due to improper or neglected lubrication. Lubrication systems have been made automatic and fool proof. The responsibility for efficient lubrication has been largely shifted from the owner to the designer and manufacturer, except, of course, in regard to the periodic replenishment of the oil in the crankcase. But in respect of the chassis, it is only quite lately that the deserved attention has been given to it. Designers now adopt one or other of the wonderfully efficient force-pump lubrication systems and install force-pump lubrication on all articulative parts of the chassis. Some designers, recognising the liability of chassis lubrication to be neglected, try and avoid it as much as possible, and we see cars in which the number of places in the chassis requiring lubrication has been reduced to one or two. No doubt we shall soon see designs which call for no lubrication at all, and in this direction we already have self-lubricating bolts and shackles which have bushes impregnated with graphite which give a dry lubrication, w'hich is efficient and long-lasting—requiring no attention. But the probable trend of design, so far as chassis mechanism is concerned, may proceed on the lines of doing aw'ay with any joints in which metal moves upon metal as a bearing. Flexible spring connections for springs, operating rods, etc., aro now available, and may become more generally used.

The designer has here a particularly wide and fascinating field for research and experiment, and maybe w'e shall eventually come to the time when the periodical filling of the crankcase or some central oil container will be all that is necessary for the complete lubrication of the whole machine. It can certainly be done; and we shall expect that much will be accomplished in this direction in the next few years. With the increasing use of the motor car by people who do not want to be bothered by any mechanical demand for self-lubricating cars will become insistent—and will be met.

ROAD MANNERS. COLONIALS ARE DISCOURTEOUS. “Comparisons are always, odious, but I am compelled to say that most of the English motorists are 50 per cent, more courteous on the road than their Dominion brethren,” writes a tourist who recently returned from a visit to England. “The London ’bus driver,” lie said, “is in my,opinion, the most- courteous person the road that'll have ever met. He is quick to give way to a following car when it is safe to pass him, but if it is not, he quickly lets you know. When there is plenty of room for you to pass, and no danger attaches to it, he draws to the side of the Toad and signals you to come on. Perhaps this is brought about by the strict supervision his company keep on him when he is driving, but if every motorist were like him motoring would be a hundred times-more pleasant. “He stands out in strong contrast to the [bus driver in vSydney, who in my opinion is a most discourteous user of the road. As a rule he never gives you any signals, and when in passing his huge and ungainly conveyance you run into danger or difficulty, ho laughs sarcastically, and more often than not makes some caustic comment. He mostly monoplises the centre of the road, and is generally a nuisance and an annoyance to every motorist. He reminds me forcibly of the English char-a-banc driver. He has the same objectionable traits, and is even more of a nuisance than the Sydney ’busman. It was not long before I added my voice to the chorus of denunciation.

Contending if more road courtesy were shown accidents would decrease, the Automobile Association of England has started a vigorous campaign of better road manners. They have got the idea from the ’buses which are wonderfully free from accidents. This the automobile association rightly attributes to the drivers’ courtesy. They are advertising the manner widely and making efforts to get legislation passed to a fine. STARTING ON HILLS. Starting on a hill involves the careful use of the hand brake, which should be eased off gradually as the clutch pedal is being released, so that the clutch picks up the load just as the brake is being freed, the engine in the meantime being revived to an extent just sufficient to prevent it from stalling. Common mistakes here are: stopping the engine by insufficiently revving or engaging the clutch too suddenly, and, worse still, allowing the car to run backwards, which may well result in a oollision with a vehicle behind. The matter of bringing a car to a standstill is another apparently simple operation but one which is frequetnly carried out in a very amateurish fashion. Apparently people simply will not devote half an hour to practising pulling up at the nearside kerb, so that one sees cars being left by ownerdrivers with the wheels- a couple of feet or more from the edge of the road,. or, as often as not, the car sticking out at an angle into the roadway. In such positions it is taking up undue space, and presents a very untidy appearance. VARIOUS NOTES. The credit balance at the bank, in the namO of the Auckland Automobile Association, at present stands at approximately £1,600.

A metal motor shield has been devised which ensures that when a pedestrian is knocked down he is pushed along' the road instead of being run over. It will bo churlish if a pedestrian, so generously treated, complains that his fountain pen is.broken.

There is a club in New York devote 1 to the laziest men in the world. Any attempt by a member to hurry is punishable by a fine. One day a member was seen driving his car past the club at a high rate of speed. Summoned before the committee, he excused himself by saying that he was too lazy to take his foot from the accelerator.

Mr. J. J. Cullen has been appointed engineer to the Auckland Automobile Association. Under arrangements wiub

1 io A.A.A. he will carry out such i orks as the inspection of second-hand i irs, which members are considering ] urchasing, and also inspect tbre cars < f members at their request. Probably i specified scale of charges will later e adopted for this sort of work, as is he case with large British and Aust- : alian motor organisations.

Brilliantly painted buses are running a New York, covered with such incriptions as “Inching up leads to rashes,” “Take time,” and “Avoid he guilty feeling—drive carefully.” Jaution is also being taught in schools ,nd the New York Austomobile Club las erected banners in the subways mpressing on everyone the urgently mportant need to “/Jive a thought to lafety.”

Before using a hack-saw blade, rub i small whetstone over any teeth that lave too much set on each side of the ilade. This will make the blade cut imoothly through metaj, and there will ae less risk of breaking any of the teeth.

With the-engine at the rear instead of in the front, a new type of automobile has been developed in Germany which affords the driver a less obstructed view of the road and in warm weather contributes somewhat to his comfort, as he is not exposed to its heat. Although the engine is only 16 horse-power, it deveips high speed and consumes relatively little gasloine. If you want to ride with rain curtains up, yet need an extip*'amount of ventilation, as on a hot day., attach them so that the second one from the front overlaps the first, and the third overlaps the second. Plenty of air will come in through tire openings without letting in the rain, unless one is driving in a downpour. In the customary way of attaching the curtains the overlapping points become airtight as the car travels faster.