Flying Machines: construction and operation Part 11

Trouble With Vertical Columns.

Vertical currents--columns of ascending air--are frequently encountered in unexpected places and have more or less tendency, according to their strength, to make it difficult to keep the machine within a reasonable distance from the ground.

These vertical currents are most generally noticeable in the vicinity of steep cliffs, or deep ravines. In such instances they are usually of considerable strength, being caused by the deflection of strong winds blowing against the face of the cliffs. This deflection exerts a back pressure which is felt quite a distance away from the point of origin, so that the vertical current exerts an influence in forcing the machine upward long before the cliff is reached.

CHAPTER XV. THE ELEMENT OF DANGER.

That there is an element of danger in aviation is undeniable, but it is nowhere so great as the public imagines. Men are killed and injured in the operation of flying machines just as they are killed and injured in the operation of railways. Considering the character of aviation the percentage of casualties is surprisingly small.

This is because the results following a collapse in the air are very much different from what might be imagined. Instead of dropping to the ground like a bullet an aeroplane, under ordinary conditions will, when anything goes wrong, sail gently downward like a parachute, particularly if the operator is cool-headed and nervy enough to so manipulate the apparatus as to preserve its equilibrium and keep the machine on an even keel.

Two Fields of Safety.

At least one prominent aviator has declared that there are two fields of safety--one close to the ground, and the other well up in the air. In the first-named the fall will be a slight one with little chance of the operator being seriously hurt. From the field of high alt.i.tude the the descent will be gradual, as a rule, the planes of the machine serving to break the force of the fall. With a cool-headed operator in control the aeroplane may be even guided at an angle (about 1 to 8) in its descent so as to touch the ground with a gliding motion and with a minimum of impact.

Such an experience, of course, is far from pleasant, but it is by no means so dangerous as might appear. There is more real danger in falling from an elevation of 75 or 100 feet than there is from 1,000 feet, as in the former case there is no chance for the machine to serve as a parachute--its contact with the ground comes too quickly.

Lesson in Recent Accidents.

Among the more recent fatalities in aviation are the deaths of Antonio Fernandez and Leon Delagrange. The former was thrown to the ground by a sudden stoppage of his motor, the entire machine seeming to collapse. It is evident there were radical defects, not only in the motor, but in the aeroplane framework as well. At the time of the stoppage it is estimated that Fernandez was up about 1,500 feet, but the machine got no opportunity to exert a parachute effect, as it broke up immediately.

This would indicate a fatal weakness in the structure which, under proper testing, could probably have been detected before it was used in flight.

It is hard to say it, but Delagrange appears to have been culpable to great degree in overloading his machine with a motor equipment much heavier than it was designed to sustain. He was 65 feet up in the air when the collapse occurred, resulting in his death. As in the case of Fernandez common-sense precaution would doubtless have prevented the fatality.

Aviation Not Extra Hazardous.

All told there have been, up to the time of this writing (April, 1910), just five fatalities in the history of power-driven aviation. This is surprisingly low when the nature of the experiments, and the fact that most of the operators were far from having extended experience, is taken into consideration. Men like the Wrights, Curtiss, Bleriot, Farman, Paulhan and others, are now experts, but there was a time, and it was not long ago, when they were unskilled. That they, with numerous others less widely known, should have come safely through their many experiments would seem to disprove the prevailing idea that aviation is an extra hazardous pursuit.

In the hands of careful, quick-witted, nervy men the sailing of an airs.h.i.+p should be no more hazardous than the sailing of a yacht. A vessel captain with common sense will not go to sea in a storm, or navigate a weak, unseaworthy craft. Neither should an aviator attempt to sail when the wind is high and gusty, nor with a machine which has not been thoroughly tested and found to be strong and safe.

Safer Than Railroading.

Statistics show that some 12,000 people are killed and 72,000 injured every year on the railroads of the United States. Come to think it over it is small wonder that the list of fatalities is so large. Trains are run at high speeds, das.h.i.+ng over crossings at which collisions are liable to occur, and over bridges which often collapse or are swept away by floods. Still, while the number of casualties is large, the actual percentage is small considering the immense number of people involved.

It is so in aviation. The number of casualties is remarkably small in comparison with the number of flights made. In the hands of competent men the sailing of an airs.h.i.+p should be, and is, freer from risk of accident than the running of a railway train. There are no rails to spread or break, no bridges to collapse, no crossings at which collisions may occur, no chance for some sleepy or overworked employee to misunderstand the dispatcher's orders and cause a wreck.

Two Main Causes of Trouble.

The two main causes of trouble in an airs.h.i.+p leading to disaster may be attributed to the stoppage of the motor, and the aviator becoming rattled so that he loses control of his machine. Modern ingenuity is fast developing motors that almost daily become more and more reliable, and experience is making aviators more and more self-confident in their ability to act wisely and promptly in cases of emergency. Besides this a satisfactory system of automatic control is in a fair way of being perfected.

Occasionally even the most experienced and competent of men in all callings become careless and by foolish action invite disaster. This is true of aviators the same as it is of railroaders, men who work in dynamite mills, etc. But in nearly every instance the responsibility rests with the individual; not with the system. There are some men unfitted by nature for aviation, just as there are others unfitted to be railway engineers.

CHAPTER XVI. RADICAL CHANGES BEING MADE.

Changes, many of them extremely radical in their nature, are continually being made by prominent aviators, and particularly those who have won the greatest amount of success. Wonderful as the results have been few of the aviators are really satisfied. Their successes have merely spurred them on to new endeavors, the ultimate end being the development of an absolutely perfect aircraft.

Among the men who have been thus experimenting are the Wright Brothers, who last year (1909) brought out a craft totally different as regards proportions and weight from the one used the preceding year. One marked result was a gain of about 3 1/2 miles an hour in speed.

Dimensions of 1908 Machine.

The 1908 model aeroplane was 40 by 29 feet over all. The carrying surfaces, that is, the two aerocurves, were 40 by 6 feet, having a parabolical curve of one in twelve. With about 70 square feet of surface in the rudders, the total surface given was about 550 square feet.

The engine, which is the invention of the Wright brothers, weighed, approximately, 200 pounds, and gave about 25 horsepower at 1,400 revolutions per minute. The total weight of the aeroplane, exclusive of pa.s.senger, but inclusive of engine, was about 1,150 pounds. This result showed a lift of a fraction over 2 1/4 pounds to the square foot of carrying surface. The speed desired was 40 miles an hour, but the machine was found to make only a scant 39 miles an hour. The upright struts were about 7/8-inch thick, the skids, 2 1/2 by 1 1/4 inches thick.

Dimensions of 1909 Machine.

The 1909 aeroplane was built primarily for greater speed, and relatively heavier; to be less at the mercy of the wind. This result was obtained as follows: The aerocurves, or carrying surfaces, were reduced in dimensions from 40 by 6 feet to 36 by 5 1/2 feet, the curve remaining the same, one in twelve. The upright struts were cut from seven-eighths inch to five-eighths inch, and the skids from two and one-half by one and one-quarter to two and one-quarter by one and three-eighths inches.

This result shows that there were some 81 square feet of carrying surface missing over that of last year's model. and some 25 pounds loss of weight. Relatively, though, the 1909 model aeroplane, while actually 25 pounds lighter, is really some 150 pounds heavier in the air than the 1908 model, owing to the lesser square feet of carrying surface.

Some of the Results Obtained.

Reducing the carrying surfaces from 6 to 5 1/2 feet gave two results--first, less carrying capacity; and, second, less head-on resistance, owing to the fact that the extent of the parabolic curve in the carrying surfaces was shortened. The "head-on" resistance is the r.e.t.a.r.dance the aeroplane meets in pa.s.sing through the air, and is counted in square feet. In the 1908 model the curve being one in twelve and 6 feet deep, gave 6 inches of head-on resistance. The plane being 40 feet spread, gave 6 inches by 40 feet, or 20 square feet of head-on resistance. Increasing this figure by a like amount for each plane, and adding approximately 10 square feet for struts, skids and wiring, we have a total of approximately, 50 square feet of surface for "head-on"

resistance.

In the 1909 aeroplane, shortening the curve 6 inches at the parabolic end of the curve took off 1 inch of head-on resistance. Shortening the spread of the planes took off between 3 and 4 square feet of head-on resistance. Add to this the total of 7 square feet, less curve surface and about 1 square foot, less wire and woodwork resistance, and we have a grand total of, approximately, 12 square feet of less "head-on"

resistance over the 1908 model.

Changes in Engine Action.

The engine used in 1909 was the same one used in 1908, though some minor changes were made as improvements; for instance, a make and break spark was used, and a nine-tooth, instead of a ten-tooth magneto gear-wheel was used. This increased the engine revolutions per minute from 1,200 to 1,400, and the propeller revolutions per minute from 350 to 371, giving a propeller thrust of, approximately, 170 foot pounds instead of 153, as was had last year.

More Speed and Same Capacity.

One unsatisfactory feature of the 1909 model over that of 1908, apparently, was the lack of inherent lateral stability. This was caused by the lesser surface and lesser extent of curvatures at the portions of the aeroplane which were warped. This defect did not show so plainly after Mr. Orville Wright had become fully proficient in the handling of the new machine, and with skillful management, the 1909 model aeroplane will be just as safe and secure as the other though it will take a little more practice to get that same degree of skill.

To sum up: The aeroplane used in 1909 was 25 pounds lighter, but really about 150 pounds heavier in the air, had less head-on resistance, and greater propeller thrust. The speed was increased from about 39 miles per hour to 42 1/2 miles per hour. The lifting capacity remained about the same, about 450 pounds capacity pa.s.senger-weight, with the 1908 machine. In this respect, the loss of carrying surface was compensated for by the increased speed.

During the first few flights it was plainly demonstrated that it would need the highest skill to properly handle the aeroplane, as first one end and then the other would dip and strike the ground, and either tear the canvas or slew the aeroplane around and break a skid.

Wrights Adopt Wheeled Gears.

In still another important respect the Wrights, so far as the output of one of their companies goes, have made a radical change. All the aeroplanes turned out by the Deutsch Wright Gesellschaft, according to the German publication, _Automobil-Welt_, will hereafter be equipped with wheeled running gears and tails. The plan of this new machine is shown in the ill.u.s.tration on page 145. The wheels are three in number, and are attached one to each of the two skids, just under the front edge of the planes, and one forward of these, attached to a cross-member. It is a.s.serted that with these wheels the teaching of purchasers to operate the machines is much simplified, as the beginners can make short flights on their own account without using the starting derrick.

This is a big concession for the Wrights to make, as they have hitherto adhered stoutly to the skid gear. While it is true they do not control the German company producing their aeroplanes, yet the nature of their connection with the enterprise is such that it may be taken for granted no radical changes in construction would be made without their approval and consent.

Only Three Dangerous Rivals.

Official trials with the 1909 model smashed many records and leave the Wright brothers with only three dangerous rivals in the field, and with basic patents which cover the curve, warp and wing-tip devices found on all the other makes of aeroplanes. These three rivals are the Curtiss and Voisin biplane type and the Bleriot monoplane pattern.

The Bleriot monoplane is probably the most dangerous rival, as this make of machine has a record of 54 miles per hour, has crossed the English channel, and has lifted two pa.s.sengers besides the operator. The latest type of this machine only weighs 771.61 pounds complete, without pa.s.sengers, and will lift a total pa.s.senger weight of 462.97 pounds, which is a lift of 5.21 pounds to the square foot. This is a better result than those published by the Wright brothers, the best noted being 4.25 pounds per square foot.

Other Aviators at Work.

The Wrights, however, are not alone in their efforts to promote the efficiency of the flying machine. Other competent inventive aviators, notably Curtiss, Voisin, Bleriot and Farman, are close after them. The Wrights, as stated, have a marked advantage in the possession of patents covering surface plane devices which have thus far been found indispensable in flying machine construction. Numerous law suits growing out of alleged infringements of these patents have been started, and others are threatened. What effect these actions will have in deterring aviators in general from proceeding with their experiments remains to be seen.

In the meantime the four men named--Curtiss, Voisin, Bleriot and Farman--are going ahead regardless of consequences, and the inventive genius of each is so strong that it is reasonable to expect some remarkable developments in the near future.