THE earlier adventurers upon aerial enterprises possessed little accurate knowledge of the properties of air. They had only their observations of the birds as a guide, and knew of no motive power save that derived from muscular energy; hence their thoughts first turned to flapping wings, to be propelled by their own exertions. Some few, as we shall see, have considered the force of the wind, but it is only since the age of steam that artificial motors of any kind have been proposed for flying machines.
The well worn legends of antiquity, concerning Dedalus, Abaris, Archytas, etc., may be passed over without comment. They merely indicate how the problem of artificial flight appealed to the imagination of men from the earliest periods, but some curious traditions will be mentioned, indicating partial successes in soaring flight, when we come to treat of aeroplanes.
About the first authentic account which we have of a proposal to provide man with flapping wings seems to be due to Leonardo da Vinci the painter, sculptor, architect. and engineer. He is said not only to have experimented with aerial screws made of paper, and to have designed a parachute, but also to have seriously contemplated building an apparatus to propel a pair of wings, of which several sketches have been found in his note-books.
FIG. 2. -- LEONARDO DA VINCI -- 1500
The first sketch shows a wing, actuated by the arms, but Da Vinci, becoming aware, upon reflection, that all possible muscles of man must be brought into play to act effectually upon the air, designs in the second and third sketches an apparatus in which the wings are to be waved downward by the legs and lifted up by the arms. The third sketch is represented in fig. 2. In this Da Vinci only shows the legs in place, so as not to obscure the construction of the parts. The date is probably about the year 1500. The construction is simple, and might not prove altogether inefficient did the muscles of man possess the same energy and rapidity of action as do those of birds in proportion to their respective weights. lt is not known just how far Da Vinci elaborated his idea, but he never put it to practical test, and it is chiefly mentioned here as a curious forerunner of actual experiments.
The first wing experiment reported by tradition seems to be that of a French tight-rope dancer named Allard who, under the reign of Louis XIV., announced that he would fly from the terrace at Saint Germain toward the woods of Vesinet in presence of the king. It is probable that he had previously succeeded in gliding short distances, but upon trial before the court his strength failed him; he fell near the foot of the terrace, and he was grievously hurt.
This probably occurred about the year 1660, and in 1678 a French locksmith named Besnier constructed a pair of oscillating wings, approximately represented in fig. 3.
FIG. 3. -- BESNIER -- 1678.
The apparatus consisted of two bars of wood hinged over the shoulders, and carrying wings of muslin, arranged like folding shutters, so as to open flat on the down stroke and fold up edgewise on the up stroke. They were alternately pulled down by the feet and by the arms, in such wise, that when the right hand pulled down the right wing, the left leg pulled down the left wing, and so on, thus imitating the ordinary movements in walking.
Besnier did not pretend that he could rise from the ground or fly horizontally through the air. He only tried short distances; having begun by jumping off from a chair, then from a table, then from a window-sill, and next from a second story, and finally from the garret, on which occasion he sailed over the roof of an adjoining cottage. He gradually grew more expert, sold his first pair of wings to a mountebank, who performed with them at the fairs, and he expected with his second pair to fly across moderately wide rivers by starting from a height, but it is not known whether he ever performed this feat.
The illustration is evidently an imperfect sketch made from a description; for the hinging at the shoulder is not shown, the attachment for pulling down the wings with the legs is evidently inefficient, and the supporting surfaces are entirely inadequate. The four wings are apparently each 3 ft. by 2 ft, say, an aggregate of 24 sq. ft. in area, while in the table of birds, to be given hereafter, it will be seen that the duck, which has the smallest bearing surface in proportion to its weight, measures 0.44 sq. ft. to the pound, and at this rate a man, weighing, say, 150 Ibs., would require wings aggregating 66 sq. ft. in area. It is probable that Besnier had even more than this, that he took short downward flights aided by gravity, but that he utterly failed when he undertook to go considerable distances
It is not stated whether the Marquis de Bacqueville had engaged in similar preliminary practice when he announced, in 1742 that he would, on a certain day, fly across the river Seine from his mansion, situated in Paris on the quay at the corner of the Rue des Saints Peres, and alight in the Tuilleries, a distance of 500 or 600 ft. A large crowd having assembled on the appointed day, the marquis, with large wings attached to his hands and to his feet, launched himself into space from the summit of a terrace jutting out from one side of the mansion.
For a space he seemed to get along well. but soon his movements became uncertain, he faltered, and then he fell, alighting upon the deck of a washerwomen's barge a short distance out into the stream. He broke his leg in the fall, and never attempted the feat again.
The Marquis de Bacqueville was judicious in trying the experiment over a water-bed, for could he have held out but a few feet further he would probably have escaped with a mere ducking. He probably glided about 120 ft. with most violent exertions, and fell when his strength became exhausted. Fig. 4, which is probably incorrect, represents the traditional apparatus with which this feat was attempted. The surfaces measure about 24 ft. in area, and are quite insufficient to sustain the weight of a man.
FIG. 4. -- DE BACQUEVILLE -- 1742.
Aware of this experiment of De Bacqueville and of its consequences, the Abbé Desforges, a canon of the church at Sainte-Croix at Etampes, invented, in 1772 a flying chariot, with two wings and a small horizontal sail or aeroplane attached, which from contemporary descriptions seem to have measured about 145 sq. ft. in aggregate area. He expected to rise from a height of a few feet above the ground, and to fly horizontally by rapidly beating his wings. Upon actual trial, the machine being held aloft by four men, the Abbé flapped violently, but utterly failed to start off. Indeed, some of the accounts say that the action of the wings pulled him down instead of up, so that he got a harmless tumble when the men let go.
In 1781 Blanchard, who subsequently became a fervent aeronaut, and who was the first to cross the British Channel in a balloon, constructed near Paris a flying chariot with four wings, measuring in the aggregate some zoo sq. ft. in area. He never exhibited the apparatus in public, having probably ascertained by private experiment that he was unable to move the wings rapidly enough to produce any useful effect.
These last two experiments, taken in connection with those previously mentioned, exhibit fairly well the two horns of the dilemma that confront inventors who endeavor to provide man with wings to be worked by his own muscular power. Either those wings have to be relatively small, in order to permit their being waved rapidly--and then they do not afford sufficient supporting area--or if they are made to approximate to the proportion which generally obtains with birds, or about one square foot to the pound, they become so large that the man does not possess the muscular power to wave them at any adequate speed.
Ideas, however, die hard, and we may disregard somewhat the chronological order of date, in order to follow the evolution of the small- wing idea, which each fresh inventor fancies has been incorrectly worked out by his predecessors.
Of these was Bourcart, who in 1866 experimented with the apparatus shown in fig. 5, It consisted of four wings with a feathering action, so that it presented the edge to the air upon the up stroke and the broad side upon the down stroke, but the results were insignificant, and the experiment was abandoned. The supporting areas measure approximately some 36 sq. it., but are only effective upon the down stroke.
FIG. 5. -- BOURCART -- 1866.
In 1873 Professor Pettigrew published his work on "Animal Locomotion," in which he called attention to the fact that birds in flapping flight, flex their wings so as to resemble a screw propeller, and that the tips describe a figure of 8 motion. This led to the inference that man had not succeeded in raising himself with wings because he had not hit upon the right motion, and in 1879 Dandrieux constructed an apparatus in which the wings were attached to an oblique axle, so as to describe a figure of 8 movement. This is represented in fig. 6, and there being but two wings in place of four, the supporting surfaces measure about 32 sq. ft. in area. The result was not satisfactory; a partial alleviation of the weight was obtained, but nothing like human flight or the hope of it.
FIG. 6. -- DANDRIEUX -- 1879.
Charles Spencer exhibited an apparatus consisting of a pair of wings measuring each 15 sq. ft. in area, to which was attached an aeroplane measuring 110 ft. more, and also a tail like a boy's dart, and a longitudinal keel-cloth to preserve the equilibrium, the whole weighing 24 lbs. and giving a sustaining surface of 140 sq.. ft. As Mr. Spencer was an athlete, he was enabled, by taking a preliminary run down a little hill, to accomplish short horizontal flights of 120 to 130 ft., in which he was wholly sustained by the air. He weighed 140 lbs., and his apparatus, which, it will be noted from the description, differed from those which propose "wings for man" by the addition of an aeroplane, measured 0.85 sq. ft. to the pound, or about the proportion of the larger soaring birds. The experiments attracted great attention at the time, but were not sufficiently encouraging to warrant pursuing the matter further.
At the same exhibition Mr. W. Gibson showed a machine consisting of two pairs of wings, worked by the hands and feet together, so as to impart a feathering movement similar to that of birds. He stated that In a former machine, having only one pair of wings of lighter construction, their action upon the air during a vigorous down. stroke was sufficient to raise the man and machine; but no practical demonstration was given, and although the inventor stated that he was then engaged in constructing a more perfect machine, nothing more has been heard of it.
Notwithstanding these many failures, the idea does not seem to be dead yet, for in September, 1890, Mr. W. Quartermain, who exhibited an explosion engine for aerial purposes in 1868, in which the motive power was derived from the gases generated from a species of rocket composition. wrote a letter to the London Engineer, in which he stated that he had abandoned his attempts to procure a light and energetic motor from hydrocarbonous matter, in favor of man's weight and muscular power, which he considers preferable, and was then engaged in experimenting with an apparatus consisting of four wings, formed after the stag beetle type, each 10 1/2 ft. long by 2 1/4 ft. wide, opposing go sq. ft. of expanse of surface to the air. This arrangement weighed 350 lbs., including 212 lbs. for the weight of the operator, who by working both handles and treadles, thus bringing all his muscles into action as well as his weight, was enabled to wave the wings, which are 25 ft. from tip to tip, so as to produce a double stroke for every single stroke of his body on the motive shaft. He describes the result as resembling that of domestic fowls flapping their wings without lifting themselves from the ground, but is of opinion that the uplifting force was greater than his weight of 212 lbs., and believes that further improvements in the mechanism, with more skilful workmanship, might produce an ascensive force greater than the whole weight of 350 lbs. This may well be doubted, for not only will it be shown hereafter that the energy of man must be less than that of birds, but none of the latter fly with so small a bearing surface in proportion to the weight-0.26 square foot to the pound-as in Quartermain's apparatus.
It has been suggested, however, that umbrella-like surfaces might prove more effective than wings, and increase the uplift to be derived from the air. Such contrivances were experimented upon by Sir George Cayley, who constructed, about 1808, a pair of wings which appear from the drawings to have been a fabric stretched tightly over a dished frame, this framework consisting of two ribs at right angles to each other, bent and tied across so as to secure rigidity. This double umbrella contained 54 sq. ft. and weighed only 11 lbs., and the inventor says: "Although both these wings together did not compose more than half the surface necessary for the support of a man in the air, yet during their waft they lifted the weight of 9 stone" (126 lbs.). It is not stated with what speed they were wafted nor with what power, but that the result did not promise to provide "wings for man" may be inferred from the fact that Sir George Cayley, in a very valuable series of articles in Nicholson's Journal for 1809 and 1810, starts out with the assertion that, in order to accomplish aerial navigation, "it is only necessary to have a first mover which will generate more power in a given time, in proportion to its weight, than the animal system of muscles."
The next experiments with umbrella wings attracted attention all over Europe. They were carried on by J. Degen, a clockmaker of Vienna, from 1809 to 1812 with the apparatus shown in fig. 7. It consisted of two wings 8 1/2 ft. wide and 22 ft. across in the aggregate, each being shaped somewhat like a poplar or an aspen leaf. They were stretched upon an umbrella-like frame and thoroughly braced back, both above and below, to a central stick by a number of small cords. The supporting surfaces consisted of bands of taffeta so attached as to have a valvular action, in order to imitate the supposed action of the feathers of birds, and the total supporting surface was 130 sq. ft., while the weight, without the operator, was stated at 20 lbs.
FIG 7. -- DEGEN -- 1812.
With this apparatus Degen, was stated, in 1809, to have risen to a height of 54 ft., by beating his wings rapidly, in presence of a numerous assembly m Vienna, and all the newspapers began to publish accounts of the performance.
These descriptions failed to mention one important addition. Degen was also attached to a small balloon capable of raising 70 lbs., so that the uplift exerted by the wings was only 70 lbs. of the 160 lbs. weight of the operator and his apparatus.
In 1812 Degen; went to Paris to exhibit his invention. He then stated that the balloon was of no sort of utility in obtaining headway, but that it was necessary as a counterpoise to maintain his equilibrium and to lighten his muscular efforts. He evidently expected by the action of his wings to drag the balloon along in still air while it lifted part of his weight
He gave three public exhibitions in Paris, but unfortunately for him, as there was wind upon each occasion, he was blown away, and on the third attempt he was attacked by the disappointed spectators, beaten unmercifully, and laughed at afterward as an impostor.
The umbrella idea had, however previously proved to be of value for parachutes, and in 1852 Letur devised the apparatus shown in fig. 8. with which he expected to direct himself through the air. by means of the wings and tail, first starting from an elevation.
FIG. 8. -- LETUR -- 1852.
In 1854 he ascended from Cremorne Gardens in London suspended about 80 ft. below a balloon manoeuvred by Mr. Adam, the areonaut, who was assisted by a friend. Letur performed several evolutions in the air by means of his wings, none of them apparently very conclusive, but in coming down near Tottenham, the wind carried the apparatus violently against some trees, and poor Letur received injuries which resulted in his death.
His apparatus measured about 660 sq. ft. in bearing surface, and had he been entirely detached from the balloon, it is possible that he might have reached the ground in safety; but it is evident that his wings would have been as of little service in enabling him to obtain more than a slight horizontal direction.
Undeterred by this sad fate, a Belgian shoemaker named De Groof designed, in 1864, an apparatus which was a sort of cross between beating wings and a parachute. His plan was to cut loose with it from a balloon, and to glide down in a predetermined direction by manoeuvring the supporting surfaces. He endeavored to make a practical experiment, both in Paris and in Brussels, but it was only in 1874 that he succeeded in doing so in London.
The apparatus is shown in fig. 9. It consisted of two wings, each 24 ft. long, moved by the arms and the weight of the operator, and of a tail 20 ft. long, which could be adjusted by the feet.
FIG. 9. -- DE GROOF -- 1864.
De Groof first went up on June 29, 1874, from Cremorne Gardens, London, attached to the balloon of Mr. Simmons. He came down safely, and claimed to have cut loose at a height of 1,000 ft., but it was subsequently stated by others that in point of fact he had not, upon this occasion, cut loose at all, but had descended still attached to the balloon. In any event, he went up again on July 5 following, with the same aeronaut, and on this occasion he really did cut loose.
The result was disastrous. As soon as, in the descent pressure gathered under the moving wings, they were seen to collapse together overhead and to assume a vertical position, when De Groof came down like a stone, and was killed on the spot.
Had the wings been prevented from folding quite back, by means of suitable stops, the descent might not have proved fatal. The area of the wings and tail, as extended horizontally, is said to have amounted to 220 sq. ft., while the weight of the man and machine was 350 lbs., or at the rate of 0.65 square foot to the pound. This corresponds to a pressure of 1.54 lbs. to the square foot, which would be generated by a velocity of 25.7 ft. per second, or a free fall from a height of 10.3 ft.; an unsafe distance for an ordinary person, but not for a trained acrobat.
Ordinary parachute practice is said to allow from 2 to 3 sq. ft. per pound, corresponding to velocities in falling of 14.7 to 12 ft. per second.
It was the most egregious folly for Letur and De Groof as well as for Cocking, who was killed in 1836 in an experiment with a parachute shaped like an inverted umbrella, to attempt a descent with an apparatus previously untried to test its strength and behavior. A few prior experiments, with a bag of sand, instead of the man, would have exhibited the action that was to be expected.
Another class of inventors of "wings for man" have endeavored to secure safety by the use of large bearing surfaces. The first of these was probably, Meerwein, architect to the Prince of Wales, in 1784 who an apparatus shaped like the longitudinal section of a spindle, separated into two wings, by a hinge at the center. It measured nearly 200 sq. ft. in area, and probably was never tried, but if it had been, it is quite certain that a man could never have imparted to the wings sufficient velocity to perform any useful effect.
The next proposal of this class was that of Bréant, who designed in 1854 the apparatus shown in fig. 10. It consisted of two wings, each measuring about 54 sq. ft. in area, and provided with three valves to relieve pressure on the up stroke. The down stroke was to be produced by the joint action of the feet and hands, and the wings were to be drawn back by elastic cords. It is not known whether it was ever tried, but it would have proved ineffective if it had been.
FIG. 10. -- BRÉANT -- 1854.
The next design was that of Le Bris in 1857, which is exhibited by fig. 11. By noting the little man working the levers in the center, the proportions of the apparatus, which seems to have measured some 550 sq. ft. in area, will be appreciated. It is said to have been experimented with in a small model, in which levers pulled down the wings which were then drawn back by springs, but it did not succeed in rising into the air, as was hoped by the inventor.
FIG 11. -- LE BRIS -- 1857.
Before proceeding to describe other designs for winged machines, to be driven by artificial motors instead of muscular power, it may be well to call attention to the fact that not only has every attempt of man to raise himself on the air by his own muscular efforts proved a complete failure, but that there seems to be no hope that any amount of ingenuity or skill can enable him to accomplish this feat.
It has been argued that there is no proof that, weight for weight, a man is comparatively weaker than a bird, and that, inasmuch as he can raise his weight in walking up a stairway, he should be able to raise it by acting upon the air with a suitable apparatus, The weak point about this argument is not only that the weight and bulk of such an apparatus become a surcharge on the muscular power of the man, as would be, for instance, the case were an artificial pair of wings applied to an ostrich, but that among the birds themselves the power to rise vertically unaided does not exist for the larger species. These have to resort to various artifices, such as running against the wind or dropping from a perch, in order to gain that initial velocity which enables their surfaces to derive support from the air, and this probably furnishes a good reason why no flying birds exceed some 50 lbs. in weight; for small animals must possess more energy in proportion to their size than large ones.
Assuming that the speed of contraction in the muscles of two similar birds of different sizes is the same, it is evident that the work done per unit of time will be in ratio to the sectional area, or as the square of the dimensions, while the weight to be moved will vary as the cube of the dimensions; hence the rate of increase between the energy and the weight will be:
square root(Energy) varies as cubed root(weight),
or to put it in the shape of formulas which shall express the relative energy of animals of the same class:
These being all merely different ways of writing it. Hence we see that the energy of birds will only increase as the 2/3 power of their weight, and that there will be an increase of size beyond which they will not be able to develop the work required for a start.3
But man is also at a further disadvantage. Not only do birds have an enormous muscular development, but their muscles contract at a much more rapid rate than those of other animals. Were men, therefore, not already relatively weaker than smaller animals, in consequence of the physical law which has been stated, they would still be unable to develop energy fast enough to rise on the air with a pair of wings. They can raise their weight, it is true, but not as quickly as the birds. They can run up a stairway at the rate of about 3 ft. per second, while the sparrows rise up vertically at thrice that speed, and fly horizontally at 22 ft. per second.
3 Thus a bird of 50 lbs. weight can do no more work in a given time than 502/3 = 13.57 similar birds each weighing 1 lb., or a bird of 1,000 lbs., did such one exist, could only develop the same foot-pounds per minute as the aggregate of 100 analogous birds, each of 1 lb. weight.
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