The Birmingham age-herald., 1918-04-28
Qn Mother Life for AprIl.I

| (In Mother Life for AprlI)
 The term stream-line has become such
 synonym for the present-day automo-
 bile body that if man in the street
 were asked what a stream-line body is,
 he would point to the first modern car
 that passed and say; There you are;
 that's what a stream-line body is" The | stream-line as applied to an automobile
 body is more a name than an actuality.
 For the high racing speeds the body shape plays an important part, and so.
 in fact, does every part of the car that
 has to be forced against the wind l Nearly everyone knows that the larger
 the frontal area is of surface going straight against the wind the harder it is to propel it. For instance, in walking against the wind on a very stormy day | it is as much as you can do to press ahe,sd. and when very bad gust comes you are apt to stand sideways and then | the force against you is considerably l Ilessened.
 l Adding this experience in wind pres sure to the Knowledge in mechanics, that | it is necessary to have sharp edge on the knife or ax to cut with, then our conclusion is that a sharp-pointed or
 knife-like shape will move through the
 air easiest. With this idea in mind it is natural that we should call the body | line which presents a fairly sharp
 front to the wind and long smooth lines along it's sides stream-hne.
 l The reason why the automobile bodies l are not true stream-line forms is that | they were all cut off sharply at the back and the long, taperng tail, which | is necessary for a stream-line, is not | there. When the sharp-nosed car cuts | into the wind hole is formed and this | has to be gradually closed up. This
 would be accomplished If it were possl-
 ble to have a long, tapering tail at the
 back of the car, but it Is obvious that | this could not be used, as it would | make the car too long.
 FISH GOOD EXAMPLE
 l Torpedoes are built with stream-lines;
 so also are fish Fish have compara. | lively hlunt noses and long tails, A true stream-lne is somewhat fish shaped. It l has rather blunt nose and it's largest | part is forward of the middle, so its
 tail begins early and is long and care | fully tapered It is proportioned In length with regard to it's diameter, and | also in other respects. The proportions may vary good dea1 but these are it's
 main characteristics. If a stream-line form is taken and its tail is cut off, | q gap CT vacuum is formed behind This vacuum Is often noticed at the | back of train. which will be seen to suck up a cloud of dust and paper be- | hind it when it is going along at a | high speed. When the stream-line body
 passes through the air, the tail fills the | gap and so gives the minimum resist
 ance to its progress
 l While the subject of air resistance l to bodies is under consideration 1t | would be well to have a general un- l dcrstanding on the Importance of air resistance to the cars ability and economy of performance. In the first place, consider the windshield resist l ence to the air. The air current
 strikes squarely on the flat surface
 and leaves a vacuum behind for a | certain distance. Various eddies and | back draughts are caused. On a road | 7ter these are extremely unpleasant l for the driver, and in a touring car the rear passengers suffer slopinz
 windshield helps to defect the air | current in a better way and also de. | creases the head-on resistance
 RESISTANCE BIG FACTOR The resistance which the car has to
 overcome is the risistance due to the | speed of the car itself plus or minus
 the speed of the wind, according to ] whether 1t is a head or tail wind. For the sake of simplicity q direct l wind will be taken so that compii-
 cated figuring can be avoided by ig- noring the side winds. In order to | determine the cars resistance to the | air, the area of the surfaces that are presented must be determined The parts to be considered are the radia-- tor, radiator mudpan. windshield.