The Fascinating Development of the Simplest Form of Travel Through the Air
AT THE START OF A BALLOON RACE from Dusseldorf, Germany, in 1937. Sixteen balloons took part in this race. Immediately before taking off a balloon is held on the ground by men round the basket, who release it at a signal given by the pilot when he is ready.
A balloon or, as it is often called, a “free” balloon, is a gas-filled or hot air-filled, engineless, spherical vessel which drifts with the wind. The word “free” distinguishes the balloon from the airship, from the moored observation balloon, and from the moored balloon used in what is known as “apron” defence against air attack.
Ballooning resembles other forms of flying only in one thing: the balloonist travels above land or sea. In a balloon, no matter at what speed the wind may be carrying it along, there is no noise, no sense of speed, no vibration. The balloon goes along with the wind and is, therefore, at all times relatively in calm. The aeronaut has no feeling of mastery over his craft, and he does not enjoy the pleasure of active driving or control. Most of the time he has nothing to do except survey the scene round and below, and keep an eye on the instrument which tells him the height, and on another instrument which informs him if the balloon has either a descending or an ascending movement. He keeps in mind the amount of ballast, having regard to the occasional or frequent need to discharge some of it. He watches the direction the balloon is taking, and sooner or later he looks out for a convenient landing place.
He is able, within limits, to control the altitude, but has scarcely any choice about the direction of travel. He is able, however, on occasion, to seek a different current of air at a higher or a lower altitude.
In the ascent from the ground there is little to enjoy. Once the balloonist is in the air,however, and his balloon, by careful management, is in fair equilibrium, he is free to enjoy the quiet. The balloon is perfectly steady; the trail rope hangs down vertically, even though the speed of travel be considerable. Except for an occasional rustle of air when the basket rotates, or when the balloon is rising or falling, there is no draught.
Few people who have been up in a balloon have not enjoyed the experience. It exercises a strong fascination. Thus, whereas a man in an aeroplane, because of the roar of the engines, hears no external sounds, the balloonist can hear everything that goes on. Sounds from below come up clearly, the barking of dogs, the whistle of a train, a hail from a man in a field.
Pleasanter than those sounds to a balloonist passing over a big wood is the trilling of thousands of birds, either in song or alarmed by the passing overhead of a monster. These sounds reach the balloonist as an indescribably sweet melody. And to the balloonist drifting quietly over the sea far from the noise of any shore, the multitudinous waves make an all-pervading murmuring of unique quality.
Good judgment and experience are needed to make an expert balloonist, but almost anyone, after one or two ascents, could avoid serious mistakes.
Landing sometimes calls for clever use of valve and ballast, and nice judgment of speed and distance, and it sometimes proves exciting, so that in the opinion of many it is the best part of the journey. There is but little risk, even in high wind, for the basket is an almost perfect shock absorber and, although the aeronaut slackens his knees for the bump, and keeps well inside, he has little cause for alarm.
MODEL OF THE FIRST HYDROGEN BALLOON in which human ascent was made. The flight, from Paris to Nesle, took place on December 1, 1783, the balloonists being the physicist Charles and a mechanic named Robert. The diameter of the balloon was twenty-six feet.
Long-distance ballooning in high wind often ends in a rough landing, and of these the writer has had a number of experiences. One of them was a steep, rapid descent to avoid passing from land to water, the fall broken by the trees of a forest. Another was in Russia, at night on snow and ice, the balloon dragging more than half a mile, the three occupants mixed up in a pandemonium of noise, and the basket finally overturning with the occupants pinned beneath it on a frozen lake.
Such experiences are exceptional, and of scores of others, in England, perhaps the most exciting was an occasion when the balloon, of which the writer was in charge, dragged well into a hop field amid the crashing of much small timber.
There is virtually no free ballooning in Great Britain nowadays, and this regrettable fact is accounted for by the greater expense it would now entail, by the encroachment of buildings over the country, and by the presence of many dangerous power cables. Great Britain, moreover, suffers, from the ballooning point of view, from the fact that the sea is never far away.
There is a widespread belief that the balloon came before the heavier-than-air machine; and, so far as general use goes, it is true we had practical ballooning before we had practical aeroplanes. But in research and experiment, mechanical flight came first, men believing that the flight of birds could be imitated by means of mechanical devices.
Among the earliest ideas of ballooning was that of Francesco Lana, who, in the seventeenth century, elaborated a theory that vessels entirely exhausted of air would ascend. He proposed using four hollow globes of copper, each twenty feet in diameter and so thin that the machine would weigh less than an equal bulk of atmosphere. The theory, however, overlooked the fact that, to be light enough to ascend, the copper vessels would have to be so fragile that they would collapse under atmospheric pressure.
The distinction of being the first practical balloonists belongs to Joseph and Etienne Montgolfier, who flourished at the end of the eighteenth century.
Hot-Air Principle
It is interesting that, at a moment when the world was on the eve of realizing the possibilities of ascents into the air by means of the displacement buoyancy of gases, the Montgolfiers should have hit upon the idea of getting the same results by using merely heated air.
As recently as 1912 the name of Montgolfier was perpetuated by the formation of a society called La Montgolfiere, which achieved some small success by reviving the hot-air balloon. The society used a system of maintaining the heat of the air in the balloon by petrol burners which could be regulated. Since the war of 1914-18 one or two large-scale experiments of this kind have been carried out, with mixed success and failure.
The first hydrogen balloon ascent in Great Britain was in 1783, James Tytler being the aeronaut.
For a century the balloon scarcely altered in design, although improvements were effected in the method of inflation, in the construction of the valve, and in the quality of the scientific instruments used. The ripping panel was another improvement. This panel was invented in 1844 by the American John Wise, and it was introduced into France by Godard in 1855.
PREPARING BALLOONS FOR FLIGHT IN A HIGH WIND at an air sports meeting at Munich, Germany. Balloons are filled with gas through the neck above the basket. The neck is then tied up in the manner seen in this picture. Before the balloon takes off the neck is untied so that gas may escape as the balloon rises. If this were not done, the pressure inside the balloon would increase to such an extent that it would probably split the envelope.
To defray the expenses of ascents, balloonists generally conducted their operations before the public, who paid to see the novelty, so that, with the exception of occasional ascents, chiefly on the Continent, ballooning became associated with the world of amusement. In 1861, however, James Glaisher obtained grants from the British Association to enable him to make scientific observations in the air, and ballooning in Great Britain was lifted out of the showman’s province. Glaisher’s systematic observations, although they have since been corrected in many important ways, were of great value. The names of Glaisher and of H. T. Coxwell, his aeronautical comrade, will be remembered, and not only for the memorable high altitude ascent of September 5,1862, from Wolverhampton. For high altitude ascents in those days oxygen apparatus was not carried. The balloon reached 29,000 feet and was still rising. Glaisher became unconscious, but Coxwell, his limbs powerless, opened the valve line with his teeth.
Burzynski, a Pole, attained a height of 35,607 feet at Warsaw in 1936, but this ascent was far surpassed in 1935 by the American aeronauts, Captains Orville A. Anderson and Albert W. Stevens, who ascended to 74,000 feet (about fourteen miles) in a special stratosphere balloon, which is not comparable with ordinary types.
For record purposes balloons are divided into eight categories, according to size. The duration and distance records were both made in balloons of about 140,000 cubic feet. The duration record is the 87-hours’ journey by the German, H. Kaulen, in December 1913, and the distance record is 1,900 miles, made by the German, Berliner, in February 1914.
The British distance record of 1,119 miles was set up by the late A. E. Gaudron, the late Air Commodore E. M. Maitland, and Major C. C. Turner (the author of this chapter), who travelled in 1908 from London to Russia in a balloon of 108,000 cubic feet. In the present century there has been a good deal of balloon racing and record-breaking. The greatest recorded speed was the 125 miles in an hour ballooned in 1902 by Captain Sigsfeld and Dr. Link, both of whom were killed in landing.
The first use of the balloon in war occurred soon after the Montgolfiers’ time. The French used it at the battle of Fleurus in 1794, shortly after the establishment of the first balloon division that ever formed part of an army. Although the French were first, the British made the most extensive and regular use of balloons in war.
Anyone can make a simple balloon demonstration. A toy balloon containing ordinary lighting gas, which is not pure coal gas but a mixture of coal and water gas of an inferior quality for balloon purposes, will ascend into the air to a considerable height. Even this small amount of gas is sufficiently buoyant to lift the weight of the envelope which encloses it. It will ascend until it reaches an altitude where the weight of the surrounding air is not more, volume for volume, than that of the gas plus the weight of the envelope. The toy balloon, however, will almost certainly burst before it reaches that height; for, unlike the practical “free”, balloon, it is distended by the gas contained in it, and it has no escape valve.
In earlier days balloons were generally more or less pear-shaped. Modern balloons are spherical, this form ensuring the greatest cubic capacity for a given quantity of envelope. This brings us to the first principles of aerostation, the operation of aircraft lighter-than-air, and to the static lift, as opposed to the dynamic lift of heavier-than-air aircraft.
The buoyancy of a gas is the difference between its weight and the weight of an equal volume of air. Once the approximate weight of each is known, it is easy to calculate the lifting power, for practical purposes, of a given quantity of gas. A small balloon of 10,000 cubic feet, inflated with hydrogen filled at sea level in a temperature of 60° Fahr., has a lift of about 700 lb, the difference between the weight of the gas and that of the air it displaces. Of such a balloon the envelope, network, basket and equipment would weigh nearly three hundredweight, leaving about 400 lb. for aeronaut and ballast. The lifting power of a balloon of the same size filled with coal gas would be no more than about 375 lb.
Even if a lighter gas than hydrogen were available the advantage would be small. Supposing such a gas weighed only 1 lb. Per 1,000 cubic feet, as against the 5 lb. of hydrogen, a gain of only 4 lb. per 1,000 cubic feet would be obtained, or 40 lb. in a 10,000 cubic feet balloon - a small advantage, even supposing the lighter gas were no more costly to produce, or that there were no disadvantages, such as greater liability to leak through the envelope.
The approximate weights of balloon gases and air per 1,000 cubic feet are hydrogen 5 lb, coal gas 35-40 lb, air 80 lb.
Helium gas, used in some air-ships, weighs about 10 or 11 lb. per 1,000 cubic feet.
A balloon has a valve on top; from the valve a rope passes down through the middle of the balloon to the basket. The aeronaut, by pulling the valve rope, lets out gas.
The ripping panel is a seam in the envelope extending from close to the valve down to the balloon’s equator. The seam has a series of breakable stops. From the top of the seam a red cord hangs down through the balloon and neck to the basket, and is securely fastened out of the way until required. The rip seam can be opened by a pulling force of about 50 lb.
Before the ripping panel came into use balloon landings in high wind were dangerous. Even in calm weather, because of the slowness of the process of emptying a balloon by valving, they were troublesome. By pulling the ripping panel cord the balloon is opened, and the gas flows out in a few seconds. In high wind the ripping cord is pulled at the moment of landing, or even before the balloon touches. Even then, in a breeze, there is generally a short landing run because of the forward impetus of the balloon.
At the bottom of the balloon envelope is a neck, which must be opened before the ascent; for the moment a balloon ascends, its gas begins to expand in the reduced atmospheric pressure, and the gas must have an outlet. There have been occasions when neglect of this precaution led to the gas making a big rent for itself in the upper part of the balloon, with disastrous results.
The neck must be of sufficient girth, but not too big. On one occasion an American aeronaut, hoping to prevent undue loss of gas through the neck, used one of greater than usual length. During the ascent, however, the gas did not find a sufficiently ready exit, and it burst the envelope.
The expansibility of the air and of all gases is the governing factor of ballooning. If an expansible envelope could be made, either on a pleating system, or by the use of some elastic material, much would be gained. Within recent years progress has been made in this direction, and the observation kite balloon and the moored balloon of air defence barrage have benefited.
The operation of the “free” balloon is much influenced by the qualities of the air, and is further complicated by the varying temperature and humidity of the atmosphere, and by the common alternations of sunshine and cloud.
THE BALLOON IN FLIGHT during the test of instruments for use in the United States stratosphere flight of 1935. The balloon contained hydrogen and ascended to a height of about five miles. Ballast bags are shown hanging along the side of the basket. The balloon is only partly filled, as the hydrogen expands when the altitude increases.
There is another factor which has an important bearing on the managing of a balloon. It is the inertia of moving bodies. A balloon which is rising or descending will continue to rise or descend past the level at which equilibrium should be reached.
There are occasions, especially at night, when in cool and equable temperature a balloon will remain for some hours at a steady altitude, regulated by the occasional discharge of a few ounces of ballast; but the procedure is generally not so simple.
The balloon, having left the ground more or less “light” will ascend to the level at which it is in equilibrium; but it will not stop there. It will rise by its ascensive impulse a little higher; while it is doing so some of its gas will pour out through the neck. Then the balloon will begin to descend; but it will not stop descending at the equilibrium point; it will go on descending, often with increasing speed, until its descent is checked by the discharge of ballast. This discharge having taken effect, the balloon will ascend again, and the procedure will be repeated. Moreover, because of the reduction of the quantity of gas, and, therefore, of the weight of the gas in the balloon, each successive equilibrium point is a little higher than the one before. This may be modified by atmospheric variations.
The distance covered depends on the velocity of the wind, but also to some extent on the skill of the aeronaut, shown by his careful judgment and timely use of ballast and valve.
Most people nowadays know, in a general way, the procedure of an aeroplane ascent, but that of the balloon is quite different. For the process of inflating, the balloon is. laid out on the ground in its net. This net terminates at the upper end in a “grummet”, or rope ring, which fits round the valve at the top of the balloon envelope. The gas is forced through the neck at. the bottom of the balloon by means of a hose, and as the balloon fills it gradually lifts, the men disposing of bags of ballast from time to time so that this procedure may be unhampered.
When the balloon is full enough, the gas is turned off, and the neck of the balloon is tied up. The basket is then placed in position and secured to the net by loops and toggles above the “hoop”, which is a few feet above the rim of the basket. Ballast for use during the voyage is arranged in bags hanging round the sides of the basket, but a great quantity of ballast, also, attached to the rigging to prevent the balloon from getting away prematurely. The pilot takes charge and places his instruments in position.
He steps into the basket, examines the statoscope, sets the hand of the altitude indicator to zero, and makes sure that he has his maps and compass. The statoscope is an instrument with a dial and pointer, and below them a thin rubber tube. Pressure of the tube in the fingers causes the point to swing to the left or right, indicating whether the balloon is ascending or falling, the slightest movement being shown. Filling operations are simple in fair weather, but in high wind the balloon has to be held in by many men, and sometimes the ascent cannot safely be made without guy ropes and the exercise of prompt judgment. The weights on the rigging are removed until the balloon is only a little heavier than air, and the pilot finally makes ready by seeing that the valve and ripping panel lines are lightly secured and ready to hand, and that the grapnel, or anchor, is hanging just outside the basket. The pilot may also give a brief pull at the valve line to make sure that it is in order.
Lastly, he “breaks” the line that has closed the neck, so that excess of gas may escape. The balloon, lightened of ballast, is now held down only by men resting their hands on the edge of the basket. The pilot, having satisfied himself that, without this restraint the balloon would rise, then gives the order to “let go”. The balloon thereupon leaves the ground, quickly or slowly, with or without lateral motion, according to circumstances.
THE IMPORTANT PARTS OF A BALLOON are illustrated in this drawing, 1 is the valve for letting out gas; 2, the ripping panel for landing purposes; 3, a drip flap for moisture running down the envelope; 4, ripping line sleeve; 5, neck of the envelope; 6, grummets for attaching the basket; 7, basket; 8, grapnel lizard; 9, trail rope lizard; 10, net.
In the basket hangs a heavy coil of some .300 feet of trail rope, secured to the rigging of the basket at one end. The pilot must see that the trail rope is attached to the basket on the same side as the ripping panel, for in landing the trail rope drags along the ground and keeps its side of the basket behind. On coming to rest the gas bag falls over to leeward, and if the ripping panel then be underneath, the gas will not get out, for the. rent will be closed by the ground. It is, therefore, necessary to make sure that in landing the ripping panel is uppermost.
The ripping line and the valve line must not be stretched; they must have plenty of slack. Otherwise, while the balloon is getting off the ground, they might be inadvertently operated by some movement of the balloon or by the stretching of the rigging. The neck line, too, must be secured to the hoop to prevent the neck and the valve lines from getting out of reach when, later, the balloon becomes flabby. The margin of lift with which to begin the voyage must depend on circumstances. If there is a strong wind the balloon must be given a strong lift to get clear. The amount of ballast kept in the balloon, or discharged for a given result, depends on sizes and weights. These are questions of proportion. At the start the pilot should stand ready with an open bag of ballast at the side of the basket ready to pour it out if the lift is insufficient for the balloon to clear obstacles.
If the balloon be rising quickly it spins slowly, and gas pours out of the neck. If falling quickly an up-draught is felt, and the neck sags upward because of the shrinkage of the gas on coming down into denser air. The pilot, however, should observe the statoscope every minute or two so that he can check any tendency to rise or fall before the tendency has become so pronounced that he will have to throw out a large quantity of ballast, or else resort to valving.
Long-Distance Ballooning
A balloon is sensitive to changes of temperature. Passing into shadow will cause it to descend, and unless this is checked by throwing out ballast the balloon will come to the ground. Passing into sunshine will expand the gas and cause the balloon to rise, but this would eventually cease to operate on attaining the highest point of equilibrium; yet the movement might go on to such a height that the ballast in reserve would not be sufficient for an easy landing. It is, therefore, sometimes necessary to valve gas out to check the ascent of the balloon.
The art of ballooning for long distances consists chiefly in careful conservation of ballast and gas. The balloonist must always remember that half a bag of ballast used at the right moment may be as good as three bags used a few minutes later on.
For long-distance ballooning it is best to start at dusk, so that the aeronauts can take advantage of the many hours of equable temperature. The writer has been in a big balloon through a long night with the discharge of no more than 50 lb. of ballast.
The trail rope is an automatic equilibrator. It is let out as soon as possible after the ascent. When the balloon has been brought down within the rope’s length of the ground the rope begins to trail. The greater the length deposited on the ground the more is the balloon lightened; and, on the other hand, as the balloon lifts more of the rope off the ground the additional load so acquired soon checks the tendency.
When it is desired to land, the necessary valving is done to bring the balloon down. The neck rope must be made fast to prevent the wind from making a huge sail of the flabby envelope when the gas escapes. As a rule, with an increasing length of rope on the ground, it takes a good deal of valving to bring the balloon down, although in high wind there is a tendency for the balloon to be blown down at the end of its rope.
If it is desirable to use the ripping panel, it should be used, as a rule, not at the first bump, but just before the balloon descends again for the second bump. By this time generally the grapnel has held, but sometimes in a breeze it carries along for a considerable distance before holding, even after the balloon has been ripped.
When the balloon is moving in really high wind it is inadvisable to use a grapnel, for the violent jerks that it would cause might be dangerous. Provided all the occupants hang on tightly inside the basket during a rough landing no harm can come to them. Finally, no one must get out of the balloon before permitted to do so by the pilot, who is always in undisputed charge.
A UNITED STATES ARMY BALLOON prepared for a race. It has been inflated in an airship shed; the nose of one airship can be seen to the right of the picture. An advantage of being able to inflate a balloon in such circumstances is that it removes any difficulties of keeping the balloon steady should the wind be strong.
Click here to see the photogravure supplement to this chapter.
A UNITED STATES ARMY BALLOON prepared for a race. It has been inflated in an airship shed; the nose of one airship can be seen to the right of the picture. An advantage of being able to inflate a balloon in such circumstances is that it removes any difficulties of keeping the balloon steady should the wind be strong.