Table for Calculating Shape of Gores for Spherical Balloons
| 0° | 1.000 |
| 3° | 0.998 |
| 6° | 0.994 |
| 9° | 0.988 |
| 12° | 0.978 |
| 15° | 0.966 |
| 18° | 0.951 |
| 21° | 0.934 |
| 24° | 0.913 |
| 27° | 0.891 |
| 30° | 0.866 |
| 33° | 0.839 |
| 36° | 0.809 |
| 39° | 0.777 |
| 42° | 0.743 |
| 45° | 0.707 |
| 48° | 0.669 |
| 51° | 0.629 |
| 54° | 0.588 |
| 57° | 0.544 |
| 60° | 0.500 |
| 63° | 0.454 |
| 66° | 0.407 |
| 69° | 0.358 |
| 72° | 0.309 |
| 75° | 0.259 |
| 78° | 0.208 |
| 81° | 0.156 |
| 84° | 0.104 |
| 87° | 0.052⅓ |
In practice, the shape of the gore is calculated by the above table, and plotted out on a heavy pasteboard, generally in two sections for convenience in handling. The board is cut to the plotted shape and used as the pattern for every gore. In large establishments all the gores are cut at once by a machine.
The raw edges are hemmed, and folded into one another to give a flat seam, and are then sewn together “through and through,” in twos and threes: afterward these sections are sewn together. Puckering must be scrupulously avoided. In the case of rubberized material, the thread holes should be smeared with rubber solution, and narrow strips of the fabric cemented over the seams with the same substance.
Varnishing is the next process, the gores being treated in turn. Half of the envelope is varnished first, and allowed to dry in a well-ventilated place out of reach of the sun’s rays. The other half is varnished when the first is dry. A framework which holds half of the balloon in the shape of a bell is usually employed. In case of haste, the balloon may be blown up with air, but this must be constantly renewed to be of any service.
The first step in varnishing is to get one side (the outer, or the inner) coated with a varnish thin enough to penetrate the material: then turn the envelope the other side out and give that a coat of the thin varnish. Next, after all is thoroughly dry, give the outer side a coat of thick varnish closing all pores. When this is dry give the inner side a similar coat. Finally, after drying thoroughly, give both sides a coat of olive oil to prevent stickiness. The amount of varnish required is, for the first coat 1½ times the weight of the envelope, and for the second coat ½ the weight—of the thin varnish. For the thick coat on the outer side ⅓ of the weight of the envelope, and on the inner side about half as much. For the olive-oil coat, about ⅛ of the weight of the envelope will be needed. These figures are approximate, some material requiring more, some less; and a wasteful workman will cause a greater difference.
The neck of the balloon (also called the tail) is in form a cylindrical tube of the fabric, sewn to an opening in the bottom of the balloon, which has been strengthened by an extra ring of fabric to support it. The lower end of the tube, called the mouth, is sewn to a wooden ring, which stiffens it. The size of the neck is dependent upon the size of the balloon. Its diameter is determined by finding the cube of one-half the diameter of the balloon, and dividing it by 1,000. In length, the neck should be at least four times its diameter.
The apex of the balloon envelope is fitted with a large valve to permit the escape of gas when it is desired that the balloon shall descend. The door of the valve is made to open inward into the envelope, and is pulled open by the valve-cord which passes through the neck of the balloon into the basket, or car. This valve is called the manœuvring valve, and there are many different designs equally efficient. As they may be had ready made, it is best for the amateur, unless he is a machinist, to purchase one. The main point to see to is that the seat of the valve is of soft pliable rubber, and that the door of the valve presses a comparatively sharp edge of metal or wood so firmly upon the seat as to indent it; and the springs of the valve should be strong enough to hold it evenly to its place.
The making of the net of the balloon is another part of the work which must be delegated to professionals. The material point is that the net distributes the weight evenly over the surface of the upper hemisphere of the envelope. The strength of the cordage is an item which must be carefully tested. Different samples of the same material show such wide variations in strength that nothing but an actual test will determine. In general, however, it may be said that China-grass cordage is four times as strong as hemp cordage, and silk cordage is ten times as strong as hemp—for the same size cords.
The meshes of the net should be small, allowing the use of a small cord. Large cords mean large knots, and these wear seriously upon the balloon envelope, and are very likely to cause leaks. In large meshes, also, the envelope puffs out between the cords and becomes somewhat stretched, opening pores through which much gas is lost by diffusion.
The “star,” or centre of the net at the apex of the balloon, must be fastened immovably to the rim of the valve. The suspension cords begin at from 30° to 45° below the equator of the envelope, and are looped through rings in what are called “goose-necks.” These allow a measure of sliding motion to the cordage as the basket sways in the wind.
For protecting the net against rotting from frequent wetting, it is recommended to saturate it thoroughly with a solution of acetate of soda, drying immediately. Paraffin is sometimes used with more or less success, but tarring should be avoided, as it materially weakens the cordage. Oil or grease are even worse.
At the bottom of the net proper the few large cords into which the many small cords have been merged are attached to the ring of the balloon. This is either of steel or of several layers of wood well bound together. The ropes supporting the basket are also fastened to this ring, and from it hang the trail-rope and the holding ropes.
Sketch showing the diamond mesh of balloon cordage and the method of distributing the rings for the goose-necks; also the merging of netting cords into the suspension cords which support the car. The principal knots used in tying balloon nets are shown on the right.
The basket is also to be made by a professional, as upon its workmanship may depend the lives of its occupants, though every other feature of the balloon be faultless. It must be light, and still very strong to carry its load and withstand severe bumping. It should be from 3 to 4 feet deep, with a floor space of 4 feet by 5 feet. It is usually made of willow and rattan woven substantially together. The ropes supporting the car are passed through the bottom and woven in with it. Buffers are woven on to the outside, and the inside is padded. The seats are small baskets in which is stored the equipment. With the completion of these the balloon is ready for its furnishings and equipment, which come under the direction of the pilot, or captain, as detailed in the preceding chapter.
Chapter XVII.
MILITARY AERONAUTICS.
The pioneer Meusnier—L’Entreprenant—First aerostiers—First aerial warship—Bombardment by balloons—Free balloons in observations—Ordering artillery from balloon—The postal balloons of Paris—Compressed hydrogen—National experiments—Bomb dropping—Falling explosives—Widespread activity in gathering fleets—Controversies—Range of vision—Reassuring outlook.
Almost from the beginning of success in traversing the air the great possibilities of all forms of aircraft as aids in warfare have been recognized by military authorities, and, as has so often been the case with other inventions by non-military minds, the practically unlimited funds at the disposal of national war departments have been available for the development of the balloon at first, then the airship, and now of the aeroplane.
The Montgolfiers had scarcely proved the possibility of rising into the air, in 1783, before General Meusnier was busily engaged in inventing improvements in their balloon with the expressed purpose of making it of service to his army, and before he was killed in battle he had secured the appointment of a commission to test the improved balloon as to its efficiency in war. The report of the committee being favorable, a balloon corps was formed in April, 1794, and the balloon L’Entreprenant was used during the battle of Fleurus, on June 26th, by Meusnier’s successor, General Jourdan, less than a year after Meusnier’s death. In 1795 this balloon was used in the battle of Mayence. In both instances it was employed for observation only.
But when the French entered Moscow, they found there, and captured, a balloon laden with 1,000 pounds of gunpowder which was intended to have been used against them.
In 1796 two other balloons were used by the French army then in front of Andernach and Ehrenbreitstein, and in 1798 the 1st Company of Aerostiers was sent to Egypt, and operated at the battle of the Nile, and later at Cairo. In the year following, this balloon corps was disbanded.
In 1812 Russia secured the services of a German balloon builder named Leppich, or Leppig, to build a war balloon. It had the form of a fish, and was so large that the inflation required five days, but the construction of the framework was faulty, and some important parts gave way during inflation, and the airship never left the ground. As it was intended that this balloon should be dirigible and supplied with explosives, and take an active part in attacks on enemies, it may be regarded as the first aerial warship.
A military dirigible making a tour of observation.
In 1849, however, the first actual employment of the balloon in warfare took place. Austria was engaged in the bombardment of Venice, and the range of the besieging batteries was not great enough to permit shells to be dropped into the city. The engineers formed a balloon detachment, and made a number of Montgolfiers out of paper. These were of a size sufficient to carry bombs weighing 30 pounds for half an hour before coming down. These war balloons were taken to the windward side of the city, and after a pilot balloon had been floated over the point where the bombs were to fall, and the time consumed in the flight ascertained, the fuses of the bombs were set for the same time, and the war balloons were released. The actual damage done by the dropping of these bombs was not great, but the moral effect upon the people of the city was enormous. The balloon detachment changed its position as the wind changed, and many shells were exploded in the heart of the city, one of them in the market place. But the destruction wrought was insignificant as compared with that usually resulting from cannonading. As these little Montgolfiers were sent up unmanned, perhaps they are not strictly entitled to be dignified by the name of war balloon, being only what in this day would be called aerial bombs.
The next use of the balloon in warfare was by Napoleon III, in 1859. He sent up Lieutenant Godard, formerly a manufacturer of balloons, and Nadar, the balloonist, at Castiglione. It was a tour of observation only, and Godard made the important discovery that the inhabitants were gathering their flocks of domestic animals and choking the roads with them, to oppose the advance of the French.
The first military use of balloons in the United States was at the time of the Civil War. Within a month after the war broke out, Professor T. S. C. Lowe, of Washington, put himself and his balloon at the command of President Lincoln, and on June 18, 1861, he sent to the President a telegram from the balloon—the first record of the kind in history.
After the defeat at Manassas, on July 24, 1861, Professor Lowe made a free ascent, and discovered the true position of the Confederates, and proved the falsity of rumors of their advance. The organization of a regular balloon corps followed, and it was attached to McClellan’s army, and used in reconnoitering before Yorktown. The balloons were operated under heavy artillery fire, but were not injured.
A small captive military balloon fitted for observation. A cylinder of compressed hydrogen to replace leakage is seen at F.
On May 24th, for the first time in history, a general officer—in this case, General Stoneman—directed the fire of artillery at a hidden enemy from a balloon.
Later in the month balloons were used at Chickahominy, and again at Fair Oaks and Richmond, being towed about by locomotives. On the retreat from before Richmond, McClellan’s balloons and gas generators were captured and destroyed.
In 1869, during the siege of a fort at Wakamatzu by the Imperial Japanese troops, the besieged sent up a man-carrying kite. After making observations, the officer ascended again with explosives, with which he attempted to disperse the besieging army, but without success.
During the siege of Paris, in 1870, there were several experienced balloonists shut up in the city, and the six balloons at hand were quickly repaired and put to use by the army for carrying dispatches and mail beyond the besieging lines. The first trips were made by the professional aeronauts, but, as they could not return, there was soon a scarcity of pilots. Sailors, and acrobats from the Hippodrome, were pressed into the service, and before the siege was raised 64 of these postal balloons had been dispatched. Fifty-seven out of the 64 landed safely on French territory, and fulfilled their mission; 4 were captured by the Germans; 1 floated to Norway; 1 was lost, with its crew of two sailors, who faithfully dropped their dispatches on the rocks near the Lizard as they were swept out to sea; and 1 landed on the islet Hoedic, in the Atlantic. In all, 164 persons left Paris in these balloons, always at night, and there were carried a total of 9 tons of dispatches and 3,000,000 letters. At first dogs were carried to bring back replies, but none ever returned. Then carrier pigeons were used successfully. Replies were set in type and printed. These printed sheets were reduced by photography so that 16 folio pages of print, containing 32,000 words, were reduced to a space of 2 inches by 1¼ inches on the thinnest of gelatine film. Twenty of these films were packed in a quill, and constituted the load for each pigeon. When received in Paris, the films were enlarged by means of a magic lantern, copied, and delivered to the persons addressed.
Spherical canister of compressed hydrogen for use in inflating military balloons. A large number of these canisters may be tapped at the same time and the inflation proceed rapidly; a large balloon being filled in two hours.
In more recent times the French used balloons at Tonkin, in 1884; the English, in Africa, in 1885; the Italians, in Abyssinia, in 1888; and the United States, at Santiago, in 1898. During the Boer War, in 1900, balloons were used by the British for directing artillery fire, and one was shot to pieces by well-aimed Boer cannon. At Port Arthur, both the Japanese and the Russians used balloons and man-carrying kites for observation. The most recent use is that by Spain, in her campaign against the Moors, in 1909.
The introduction of compressed hydrogen in compact cylinders, which are easily transported, has simplified the problem of inflating balloons in the field, and of restoring gas lost by leakage.
The advent of the dirigible has engaged the active attention of the war departments of all the civilized nations, and experiments are constantly progressing, in many instances in secret. It is a fact at once significant and interesting, as marking the rapidity of the march of improvement, that the German Government has lately refused to buy the newest Zeppelin dirigible, on the ground that it is built of aluminum, which is out of date since the discovery of its lighter alloys.
The German military non-rigid dirigible Parseval II. It survived the storm which wrecked the Zeppelin II in April, 1910, and reached its shed at Cologne in safety.
Practically all the armies are being provided with fleets of aeroplanes, ostensibly for use in scouting. But there have been many contests by aviators in “bomb-dropping” which have at least proved that it is possible to drop explosives from an aeroplane with a great degree of accuracy. The favorite target in these contests has been the life-sized outline of a battleship.
The German military Zeppelin dirigible, which took part in the manœuvres at Hamburg in April, 1910, and was wrecked by a high wind at Weilburg on the return journey to Cologne.
Glenn Curtiss, after his trip down the Hudson from Albany, declared that he could have dropped a large enough torpedo upon the Poughkeepsie Bridge to have wrecked it. His subsequent feats in dropping “bombs,” represented by oranges, have given weight to his claims.
By some writers it is asserted that the successful navigation of the air will guarantee universal peace; that war with aircraft will be so destructive that the whole world will rise against its horrors. Against a fleet of flying machines dropping explosives into the heart of great cities there can be no adequate defence.
On the other hand, Mr. Hudson Maxim declares that the exploding of the limited quantities of dynamite that can be carried on the present types of aeroplanes, on the decks of warships would not do any vital damage. He also says that many tons of dynamite might be exploded in Madison Square, New York City, with no more serious results than the blowing out of the windows of the adjacent buildings as the air within rushed out to fill the void caused by the uprush of air heated by the explosion.
The Lebaudy airship “La Patrie.” As compared with the first Lebaudy, it shows the rounded stern with stabilizing planes, and the long fin beneath, with rudder and dipping planes.
As yet, the only experience that may be instanced is that of the Russo-Japanese War, where cast-iron shells, weighing 448 lbs., containing 28 lbs. of powder, were fired from a high angle into Port Arthur, and did but little damage.
In 1899 the Hague Conference passed a resolution prohibiting the use of aircraft to discharge projectiles or explosives, and limited their use in war to observation. Germany, France, and Italy withheld consent upon the proposition.
In general, undefended places are regarded as exempt from attack by bombardment of any kind.
Nevertheless, there are straws which show how the wind is blowing. German citizens and clubs which purchase a type of airship approved by the War Office of the German Empire are to receive a substantial subsidy, with the understanding that in case of war the aircraft is to be at the disposal of the Government. Under this plan it is expected that the German Government will control a large fleet of ships of the air without being obliged to own them.
And, in France, funds were raised recently, by popular subscription, sufficient to provide the nation with a fleet of fourteen airships (dirigibles) and thirty aeroplanes. These are already being built, and it will not be long before France will have the largest air-fleet afloat.
The results of the German manœuvres with a fleet of four dirigibles in a night attack upon strong fortresses have been kept a profound secret, as if of great value to the War Office.
In the United States the Signal Corps has been active in operating the Baldwin dirigible and the Wright aeroplanes owned by the Government. To the latter, wireless telegraphic apparatus has been attached and is operated successfully when the machines are in flight. In addition, the United States Aeronautical Reserve has been formed, with a large membership of prominent amateur and professional aviators.
Some military experts, however, assert that the dirigible is hopelessly outclassed for warfare by the aeroplane, which can operate in winds in which the dirigible dare not venture, and can soar so high above any altitude that the dirigible can reach as to easily destroy it. Another argument used against the availability of the dirigible as a war-vessel is, that if it were launched on a wind which carried it over the enemy’s country, it might not be able to return at sufficient speed to escape destruction by high-firing guns, even if its limited fuel capacity did not force a landing.
Even the observation value of the aircraft is in some dispute. The following table is quoted as giving the ranges possible to an observer in the air:
| Altitude in feet. | Distance of horizon. | |
|---|---|---|
| 500 | 30 | miles. |
| 1,000 | 42 | “ |
| 2,000 | 59 | “ |
| 3,000 | 72 | “ |
| 4,000 | 84 | “ |
| 5,000 | 93 | “ |
As a matter of fact, the moisture ordinarily in the air effectually limits the range of both natural vision and the use of the camera for photographing objects on the ground. The usual limit of practical range of the best telescope is eight miles.
All things considered, however, it is to be expected that the experimenting by army and navy officers all over the world will lead to such improvement and invention in the art of navigating the air as will develop its benevolent, rather than its malevolent, possibilities—“a consummation devoutly to be wished.”
Chapter XVIII.
BIOGRAPHIES OF PROMINENT AERONAUTS.
The Wright Brothers—Santos-Dumont—Louis Bleriot—Gabriel Voisin—Leon Delagrange—Henri Farman—Robert Esnault-Pelterie—Count von Zeppelin—Glenn H. Curtiss—Charles K. Hamilton—Hubert Latham—Alfred Leblanc—Claude Grahame-White—Louis Paulhan—Clifford B. Harmon—Walter Brookins—John B. Moisant—J. Armstrong Drexel—Ralph Johnstone.
On January 1, 1909, it would have been a brief task to write a few biographical notes about the “prominent” aviators. At that date there were but five who had made flights exceeding ten minutes in duration—the Wright brothers, Farman, Delagrange, and Bleriot. At the close of 1910 the roll of aviators who have distinguished themselves by winning prizes or breaking previous records has increased to more than 100, and the number of qualified pilots of flying machines now numbers over 300. The impossibility of giving even a mention of the notable airmen in this chapter is apparent, and the few whose names have been selected are those who have more recently in our own country come into larger public notice, and those of the pioneers whose names will never lose their first prominence.