The Probert Encyclopaedia of Aircraft

AERONAUTICS

Aeronautics is the art of sailing in or navigating the air. The first form in which the idea of aerial locomotion naturally suggested itself was that of providing men with wings by which they should be enabled to fly. By about 1905, however, it was generally admitted that it is impossible for man by his muscular strength alone to give motion to wings of sufficient extent to keep him suspended in the air. Hence later attempts at aerial navigation structures of a different kind were generally tried, such as some sort of flying car, elevated and propelled by machinery which eventually gave rise to the modern aircraft, or a vehicle so buoyant as to float in the air, the balloon being the most common. Early pioneers in flight encountered one great difficulty in that of supporting in mid-air a sufficient weight of machinery to provide the necessary power for propelling and steering purposes.

The navigation of the air by means of the balloon dates only from nearly the close of the eighteenth century. In 1766 Henry Cavendish showed that hydrogen gas was at least seven times lighter than ordinary air, and it at once occurred to Dr. Black of Edinburgh that a thin bag filled with this gas would rise in the air, but his experiments were for some reason unsuccessful. Some years afterwards Tiberius Cavallo found that a bladder was too heavy and paper too porous, but in 1782 he succeeded in elevating soap-bubbles by inflating them with hydrogen gas. In this and the following year two Frenchmen, the brothers Stephen and Joseph Montgolfier, acting on the observation of the suspension of clouds in the atmosphere and the ascent of smoke, were able to cause several bags to ascend by rarefying the air within them by means of a fire below. These experiments roused much attention at Paris; and soon after a balloon was constructed under the superintendence of Professor Charles, which being inflated with hydrogen gas rose over 3000 feet in two minutes, disappeared in the clouds, and fell after three quarters of an hour about fifteen miles from Paris. These Montgolfier and Charles balloons already represented the two distinct principles in respect to the source of elevating power for balloons, the one being inflated with common air rarefied by heat, requiring a fire to keep up the rarefaction, the other being filled with gas lighter at a common temperature than air, and thus rendered permanently buoyant. Both forms were used for a considerable time, but the greater safety and convenience of the gaseous inflation finally prevailed. After the use of coal-gas had been introduced it superseded hydrogen gas, as being much less expensive, though having a far less elevating power.

The first person who made an ascent in a balloon was Pilatre de Rozier, who ascended 50 feet at Paris in 1783 in one of Montgolfier's. A short time afterwards M. Charles and M. Robert ascended in a balloon inflated with hydrogen gas, and travelled a distance of 27 miles from the Tuileries; M. Charles by himself also ascended to a height of about two miles. Since then a multitude of ascents and aerial voyages were made, with, strange to say, comparatively few disastrous results in the early years. Among the names of the earlier balloonists we may mention Lunardi, who first made an ascent in Great Britain in September 1784, unless we assign this honour to J. Tytler (' Balloon' Tytler), who seems to have made two short ascents from Edinburgh in the preceding month; Blanchard, who, along with the American Dr. Jeffries, first crossed the Channel from Dover to Calais, in January 1785; Garnerin, who first descended by a parachute from a balloon in October 1797; and Gay Lussac, who reached the height of 23,000 feet in September 1804.

In 1836 a balloon carrying Messrs. Green, Holland, and Mason traversed the 500 miles between London and Weilburg in Nassau in eighteen hours. In 1859 Mr. J. Wise, the chief of American aeronauts, accompanied by several others, rose from New York, and landed, after a flight of 1150 miles, in twenty hours. In September 1862, the renowned aeronaut, Mr. Glaisher, accompanied by a Mr. Coxwell, made an ascent from Wolverhampton, and reached the estimated elevation of 37,000 feet, or 7 miles, a height far greater than any other then attained, if it can be depended on as exactly ascertained. But the aeronauts were for a time in great peril, Mr. Glaisher having become insensible, and Mr. Coxwell having his hands so severely frozen that he was unable to pull the valve for descent, and was compelled to use his teeth. Early aeronauts were clearly unaware of the thinning of the atmosphere and dramatic reduction in temperature with altitude. It is claimed that the first greatest really authentic height-35,000 feet-was attained by two German aeronauts at Berlin in 1901. The most daring early attempt at an aerial voyage was that of the Swede, Andree, who, with two companions in 1897 ascended from Spitzbergen in hopes of reaching the North Pole, their fate remaining unknown.

All the features of the ordinary balloon as now used are more or less due to Professor Charles, already mentioned. Early balloons were usually a large pear-shaped bag, made of pliable silk cloth, covered with a varnish of caoutchouc dissolved in oil of turpentine to render it air-tight. The ordinary size ranged from 20 to 30 feet in equatorial diameter, with a proportionate height, but balloons of far greater dimensions were also constructed. A car, or basket, generally of wicker-work, supported by a network which extends over the balloon, contained the aeronaut; and a valve, usually placed near the top, and to which is attached a string reaching the car, gave him the power of allowing the gas to escape, whereby the balloon lowered at pleasure. A quantity of sand ballast in small bags was usually taken, and when the balloon tended to descend too far sand was thrown out and it rose again. The guide-rope, a long and heavy rope trailing over the ground, was sometimes used when the country was such that no serious damage would result from its trailing. The principle of this device was that as the balloon tended to rise it must lift more of the rope off the ground, while when the balloon sunk it was relieved of so much weight, and thus it tended to float at one level above the ground.

The problem of how to steer or propel a balloon in a desired horizontal direction was an early issue and numerous attempts at producing navigable balloons were made at the start of the 20th century. In a navigable balloon to be propelled through the air by some kind of motor, against the wind if necessary, the familiar balloon shape was departed from as quite unsuitable, and the 'air-ship' usually of an elongated form and more or less cylindrical or cigar-shaped adopted. A design still used a hundred years later.

Balloons of a fish or cigar shape, floated by gas, and propelled by a screw driven by a dynamo-electric machine, and steered by a large rudder, made several ascents in Paris in 1884 and 1885; and being generally able to return to the starting-point, at the time it was claimed for them that they had settled the question of balloon steerage, but it was several years before the matter was settled. The names of Count Zeppelin and M. Santos Dumont became well known in connection with such balloons. In 1897-1900 the former constructed a huge cylindrical air-ship of great length, with parabolic ends, divided into a number of separate chambers filled with hydrogen gas and these enclosed in an outer air balloon, the whole being braced and made rigid by an aluminium framework, and the means of propulsion being screws driven by Daimler petrol motors and fixed to the longitudinal axis of the air-ship. The success of this great structure, even after various improvements were introduced, appears to have been only partial, and want of sufficient funds brought operations to a stop for a while. M. Santos Dumont constructed several navigable balloons, and one of them was so successful at Paris in 1901 as to gain a prize of 100,000 francs. On this occasion his airship made the journey from St. Cloud to the Eiffel Tower and back again, a distance of about 9.5 miles, in half an hour. M.M. Lebaudy of Paris also made some very successful trips with a dirigible balloon ; that is, one that can be steered or directed-to some extent at least.

In 1903-4 a large air-ship was constructed by Dr. F. A. Barton at Alexandra Park, London. This structure had a bamboo framework suspended below it, connected with which was the propelling machinery, two engines each of 4.7 ihp, driving a series of fans, there being a large square sail serving as a rudder. In 1905 an improved form of this air-ship was experimented with, the name Barton-Rawson air-ship, 'designed for the War Office', later being given to it. In this form it consisted of a silk balloon 180 feet long and 40 in diameter, with a bamboo car 127 ft. long and 18 ft. high, carrying a 50-horsepower motor at either end driving four propellers 7 ft. in diameter and revolving at a high speed, the total weight being about 14,000 lbs. Ascents made in July 1905 were not very successful, the air-ship driving with the wind and being unable to take a course of its own. The British War Office expressed its readiness to give an order for an air-ship on certain conditions, one being that it must be able to turn in a circle of 100 yards radius.

Besides balloons, which are lighter than a corresponding volume of air, and air-ships depending on the same principle, various apparatus were constructed for aerial navigation that are heavier than the air at the start of the 20th century at a time when the feasibility of attaining success with such was supported by the flight of birds, many of which are decidedly heavy compared with their expanse of wing. Some of these apparatus were intended more for gliding or soaring through the air than for actual flight, having somewhat the nature of a huge bird with outstretched wings, beneath which a man attached himself, and on springing from a height gradually descends to the bottom - an idea revisited some years later for the hang-glider.

The kite, or structures on the same principle, were much experimented with, and it was found considerable weights can be raised and carried in this way. The kite rises in the air if drawn along by its string, and if instead of drawing it along a propeller is fitted to drive it through the air it ought to ascend in the same manner. Hence the invention of the aeroplane, which shows a large flat surface contrived to float nearly horizontally in the air, but with the front edge very slightly raised, so that in being propelled rapidly along it receives the pressure of the air on the under side, the air thus tending to counteract the force of gravity. Sir H. S. Maxim in 1894 constructed a huge machine with main and several subsidiary aeroplanes, propelled by two large screws driven by steam-engines of 300 hp, and able to rise with a great weight. As a model, at least, Prof. Langley's aerodrome had some success, flying through the air a distance of three-quarters of a mile. It had two rigid pairs of wings about 12 ft. in width, with large screw-propellers between them driven by a small steam-engine. Aviation is the term applied to attempts at flight otherwise than by balloons.

Manned balloons were successfully used for taking meteorological and military observation from the end of the 19th century. The latter class of balloons were usually 'captive' balloons - balloons that are kept by a rope from going farther than is desired, and that can be drawn back at will. Their use was only really suited for fairly calm weather and in certain circumstances. The balloon may have had a telephone connection with the earth below. There was a balloon service in the British army, the duties falling upon the Royal Engineers. Since about 1900 small captive and other balloons have sent up for purely scientific purposes, unaccompanied by any person, but provided with self-recording thermometers, barometers, etc., by which valuable facts have been ascertained. Some of these early balloons reached heights of 60,000 or 70,000 feet. During the siege of Paris in 1870-71 over sixty persons (including Gambetta) and innumerable letters left the city in balloons.
Research Aeronautics