Just What Do You Mean By Streamlining?
WARREN B. HASTINGS
Speed through the air has been attained as much by the design of airplanes as by the development of their power units. In the United Stales and Europe revolutionary changes in the design of railway trains are likely if present experiments are successful. We are entering an epoch of streamlined transportation. That will be more apparent to the motorist of 1934 than it has been to lhè motorist of 1933. Just what is “streamlining?” What are its practical results? How does it work? We asked Warren B. Hastings, Secretary of the Canadian Section of the Society of Automotive Engineers, to explain. This article is the result.—The Editor.
WIND RESISTANCE exacts a gasoline tax from Canadian motorists which averages annually between twenty and twenty-five dollars per capita. Half the power developed by the engine of a conventional car—half the gasoline it consumes—is used in overcoming wind resistance at forty miles per hour. Practical streamlining obviates wind resistance in large part and therefore eliminates proportionately its extortionate toll.
Sir Dennistoun Bumey, designer and builder of the R-100, inventor of the paravane and designer of the Bumey Streamline “8,” which remains possibly the world’s most prophetic car, in the course of an address to the Canadian Club in Toronto, said that if the motor vehicles of Canada were streamlined, their owners would be saved twenty-five million dollars per annum in gasoline disbursements alone, to say nothing of concomitant advantages in improved performance and oil, tire and other economies, including, of course, reduced wear and tear with all that that implies in maintenance costs and life of units.
“Something ought to be done about it,” you say. Fortunately, something is being done about it.
You will note that I used the phrase “practical streamlining.” For there are practical limits to the application of the lessons of aerodynamics to motor vehicles. It was, I think, William B. Stout, President of the Stout Engineering Laboratories, Inc., who stated recently that the United States airship, Akron, would not do more than six miles an hour if it were no better streamlined than the then average motor car. Now, obviously, the motor car cannot be designed as well aerodynamically as a dirigible. It has to run on wheels. Its length and tail overhang must not be such as to compromise its behavior in congested traffic or in cramped quarters. Its height and breadth likewise must be held within limits determined by the practical considerations dictated by its primary functions. But this should not be construed as indicating that motor cars cannot be designed much more in conformity with aerodynamic principles than
they have been. They can and will be—and that very soon.
It was not until about three years ago that the first production car appeared on this continent in which any conscious application of the lessons of aerodynamics had been made. It initiated a new trend in body design that has swept the industry. Change for the sake of change in body styling was supplanted by a progressive approach to the objective of practical streamlining.
Thus far the advance has been much more apparent than real. From the point of view of aerodynamics, the conventional car of 1933 was just a little better streamlined than was the car of a decade ago. Almost all of the last season’s sedans were better streamlined going backward than forward. Wind tunnel tests showr that the relative wind resistances of a typical 1922 sedan is fifty-six per cent, a 1930 sedan is fifty-three per cent, a so-called streamlined 1933 sedan is forty-four per cent, and a scientifically streamlined automobile is sixteen per cent, the standard being the 100 per cent wind resistance of the flat plate.
Why, then, has the progress toward the objective been at such a slow pace? The answer is simply: the inertia of public opinion plus economic inertia. The automobile industry’s chieftains know from experience that it is equally as costly to anticipate by much the march of public opinion as it is to lag much behind it.
Economic inertia has reference to the enormous cost of junking the huge investment in dies, jigs, tools—in short, the machinery of car production and of the retooling that would be entailed in the production of practically streamlined cars.
It is not “in the picture” that any leading manufacturer would have the audacity at this time to stake his company’s existence on the production of a three-wheel dirigible-bodied car with engine in the rear such as Frank Spring, engineering stylist, pictured in a recent address to the Canadian Section of the Society of Automotive Engineers. It is very much in the picture that some leading manufacturers this year will offer cars that, in the matter of streamline design, are as far ahead of the production cars of 1933 as the 1933 cars were ahead of the first horseless carriages.
NOW there are many fallacies entertained by the public about overcoming wind resistance and other objectives of streamlining. Everyone knows that air resists passage through it or tends to push along or over anything that resists its movement. The energy required
Rear Vacuum Decreases Speed
to wave a fan, the power windmills develop, the movement of sailing craft, the umbrella or parasol blown inside out, the pull of a car door opened ia the direction of travel at speed, the damage done by windstorms in northern climes, the action of cyclones and the pursuit of a wind-lifted hat, are but a few of many examples more or less familiar to everyone.
Everyone knows that it is easier to cope with the resistance of solids with a sharp knife or chisel than with a dull or blunt one. Therefore it seems reasonable to those not in the know that air resistance should be dealt with similarly. Sharp prows on ships have tended to confirm this opinion, as have the points on arrows, javelins and projectiles. It is in accord with this opinion that we have sharp-nosed cars suggestive of snowplows.
If wind resistance consisted entirely of head resistance, as appears to be generally assumed, then the shape of the conventional car would be logical. But head resistance is a minor, not a major, factor in wind resistance. The major factor is the partial vacuum or area of reduced pressure behind the moving body.
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Have you stood on the rear platform of a train, tossed out a piece of paper and watched it? If so, it is probable that you observed the paper swirling and following the train for quite some time.
Possibly, if your memory was on duty, your eyebrows lifted incredulously when you read recently that Van Hout and Richards had both broken an unpaced cycling record that had stood for nineteen years when they each rode nearly twentyeight miles in an hour. Possibly your memory recalled that cyclists had pedalled behind trains at mile-a-minute speeds and that one had done seventy-six miles an hour when paced by a motorcycle. The reason for these paced speeds and the explanation of the great disparity between the paced and unpaced records is the area of low pressure, the partial vacuum or, in popular parlance, the suction created by the pacing trains and motorcycle. It takes much energy to create this suction, which is descriptively known as “drag.” It is because of this drag primarily that the conventional cars of 1933 were better streamlined going backward than forward. It is the answer to the question: Why does so much more dust collect on the back of a car than anywhere else on its body?
Some time ago, on Muroc Dry Lake, a group of automotive engineers watched a car with a streamlined body do 150 miles an hour in a test. Down the stretch they noticed a conventional sedan proceeding at approximately fifty miles an hour. Someone drew attention to the fact that in the wake of the sedan there were billowing clouds of dust, while in that of the streamlined test car there was a relatively trivial dust disturbance. Remember that the test car was travelling at triple the rate of speed of the sedan and that wind resistance increases as the square of the speed, and something of the significance of that chance visual demonstration of the advantage of streamlining will be appreciated.
It has been pointed out that a conventional coupé will haul a semi-streamlined touring trailer of 1.500 pounds or more at a higher rate of speed than the car can attain alone, which is another illuminating commentary on air drag and the need for its obviation by streamlining.
Ships, like cars and trains of conventional design, are hampered in their progress by the drag they create and, of course, by the turbulences and vortices caused by protuberances and discontinuities of all kinds. These are bad enough in themselves, but in concert, through interaction, their effect is much more adverse than the sum of their individual resistances. Even in pre-war days we were taught in our universities that at sixty miles an hour air resistance exceeded all other resistances combined with which railroad trains must cope. Significant of the isolation and somnolence of rail rolling stock engineering is the fact that the world’s steam train record which still stands—112^ miles per hour—was established by the Empire State Express forty years ago. In that year, 1893, the first Toronto unit—Church Street —was electrified by the Toronto Street Railway Company, and Frederick B. Fetherstonhaugh built and operated Canada's first automobile.
The creation of partial vacuums has its uses. Approximately three-quarters of the lift of an airplane is due to the partial vacuum created over the wings. That is mentioned simply as another indication of the potency of the force that drags at your car and mine with such extravagantly costly effectiveness because they are not practically streamlined.
It is not so many years ago that the Schneider Trophy was won by a 160 horsepower seaplane at a speed of sixty miles an hour. That was in 1915. Two years ago it was won by an English Supermarine of 2.300 horsepower at a speed of 340 miles an hour. Had that Supermarine been no better
streamlined than the 1915 winner of the world’s most coveted air trophy, then an engine of between 29,000 and 30,000 horsepower would have been required to propel it at the speed achieved. Figure it out for yourself.
What Tests Have Shown
XT ATURE was the first great streamliner and remains the greatest. A little muscid fly holds the world’s speed record by a comfortable margin. Entomologists tell us that it achieves a velocity in flight of more than 500 miles an hour. Nature, long before the advent of man, was conforming to aerodynamic principles both animals and vegetaDles and especially all animals which depend on speed to capture or avoid capture. The laws of “the survival of the fittest” and “natural selection” thus developed the excellent examples of streamlining found in aquatic plants that have to withstand fast flowing streams, in fastflying birds, insects, and fast-swimming fish. It is not without significance that the fastest automobile in the world—272 miles an hour —while named The Bluebird by its gallant pilot, Sir Malcolm Campbell, was nicknamed the Whale by the public because its shape suggested that of the largest of mammals. If you have seen the arresting new book Horizons, by Norman-Bel Geddes, eminent artist and architect, that nickname will bring to your mind the fact that his illustrations of ocean liners of tomorrow have conformations that resemble those of whales more than those of the steam leviathans of today.
The first passenger car to which the lessons of aerodynamics were applied was the Rumpler Tropfen—and that is the origin of the now popular designation, “drop design,” for tropfen is German for “drop.” Dr. Rumpler, an aircraft designer, gave his car that name because he had given it the form to which a raindrop is molded by wind resistance when falling through still air. Fishleigh added “tear” and so the expression “tear drop” came into currency for no good reason that one can think of.
The collective effect of little things in wind resistance is well illustrated by the fact that Burney’s car. as a stripped chassis, did just sixty-four miles an hour. With the heavy streamlined body superimposed, it did eighty miles an hour. Remember, the Burney had an engine of five less horsepower than the V-eight Ford and was much longer and more commodious than any production car.
I have before me the data of many tests with and without streamline bodies. Reference to one or two more will have to suffice. Studebaker conducted some tests on its proving ground two years ago. A President sedan with the standard 125 horsepower engine did eighty miles an hour. With a special 200-horsepower engine, the same car did 9312 miles an hour. Then the stock motor was reinstalled, the stock body supplanted with a semi-streamline body and the car did between 107 and 108 miles an hour. The Pierce-Arrow “12” with the Silver Arrow superstructure—a centre of interest at the last Canadian National Exhibition Motor Show—is said to be twenty-two miles an hour faster than the same chassis v. ith the standard sedan body.
Now obviously the peak speeds per se are of little more than academic interest to the lay motorist. They are mentioned because of their implications of improved performance and economy within the normal driving range, and are therefore of no mean significance to every motorist. The JarayChrysler demonstrated this. Jaray designed and built a streamline sedan body for a standard Chrysler “6” which, larger and heavier than the stock body, increased the car’s speed considerably and reduced fuel consumption by forty per cent.
The shape of a dirigible is that of an elongated egg. Not long ago Charles Ketter-
ing, vice-president of General Motors in charge of research, was reported to have said the streamlining trend is going to eventuate in cars being egg-shaped and that the “egg is peerless in aesthetic symmetry.” More recently, one of our eminent summer Canadians, Fred M. Zeder, vice-president in charge of Engineering, Chrysler Corporation, declared: “It takes courage, honesty and willingness to scrap the obsolete. We should be willing and glad to make changes. We are living in the most stirring times in the history of transportation. Progress, progress and then more progress is necessary to solve the depression.” All of which may or may not be apposite to the subject but is certainly not without significance.
In 1932 the Graham Blue Streak was introduced. Many automobile men said: “Yes, Amos Northup has done a good job
but—ye gods! she’s much too radical in lines for public acceptance.” More Graham Eights were sold that year than ever before. Last year there were a number of cars as radical in superstructure design as the Graham, including the Ford. By such means as these the industry has learned that the general public is not as intransigently conservative as it had supposed.
Will practically streamlined cars look queer? If the yardstick is so-called orthodox design, then the answer is “yes.” If it is utilitarian, then it is an emphatic “no.” If it is symmetry', grace, proportion, again it is “no.”
If “all our past proclaims our future,” there is reason to believe that another era of rapid development is at hand. Certainly we are entering the streamlined epoch of transportation awheel, afloat and a-wing.