Gustave Whitehead: First in Flight breaking news
true flying replica of the Wrights' 1903 Flyer
https://www.youtube.com/watch?v=o1mscspl-VU
I'm sure our Alaskan friend is somewhere it that comment section.
Wherever you may be "Simplex" - thanks for the fun and yeah, that looks like a powered glide to me.
Has anybody got any details of the machine or results regarding the 100th anniversary celebratory attempt with the USAF Lady Pilot ( IIRC) ?
I gather there were some problems regarding weather etc.
I gather there were some problems regarding weather etc.
Megan, thank you for posting those videos. The impression I get is that it would take a lot of dedication and just the right conditions to replicate the 1903 flight for the following reasons:
The FIVE FIRST FLIGHTS
- The Wright brothers had been flying their gliders for four years and were ready for the lack of pitch stability by the time they flew the powered machine.
- With the wind at Kill Devil Hill the Flyer was already flying (supported by the air) before it started moving on its rail, so acceleration to flying speed was not necessary for lift or control, only positive pitch on the canard.
- The gusty conditions permitted maximum use to be made of the gusts and wind gradient, so adding energy to the aircraft (as dynamic soaring does).
The FIVE FIRST FLIGHTS
Last edited by Mechta; 26th Jun 2015 at 15:18. Reason: 'only only' replaced with 'only one'
Yours shows a 1905 replica
http://www.wrightflyer.org/wp-conten...est-Pilots.pdf
The following deals specifically with the 1903 model.
http://authors.library.caltech.edu/2...Laiaawfp84.pdf
Has anybody got any details of the machine or results regarding the 100th anniversary celebratory attempt with the USAF Lady Pilot
http://worldairlinenews.com/2015/03/...egend-retires/
Forgot to add this of the 1903 replica.
http://www.wrightexperience.com/edu/...1903_paper.pdf
Last edited by megan; 26th Jun 2015 at 01:48.
Just watched the Pathe film of the "first flight" - as I wrote in an earlier post, the aircraft was helped off the ground by energy from a falling weight, and seemed to spend a lot of the flight in "ground effect", but nevertheless an epic achievement- I will stand by for the "incoming"!!
Many thanks indeed for the references megan. I found it interesting to read the 1903 replica/sim paper and compare it to the Carrol F Grey paper kindly referenced by Mechta ( I also go along with his reasoning)
Wander00, may I suggest that you might also find that these two papers provide informative reading?
Wander00, may I suggest that you might also find that these two papers provide informative reading?
Aah, thanks - but I am still unclear whether or not there was a "falling weight" mechanism for the first flight, or am I remembering seeing the later film in my childhood (a long time ago)
With reference to the attempted 2003 reenactment of the Dec 17th 1903 event.
It would appear that the aircraft was indeed the Wright Experience's 1903 replica air-frame and engine pointed out by megan.
It was quite a rainy day at Kitty Hawk on Dec 17th 2003 so the replica's flight demonstration was somewhat delayed.
If I may quote the witness account of the Editor of " Aeroplane" ,writing in the March 2004 issue p.p.26
"In the end the the weather improves marginally and the Flyer is wheeled out, but there is insufficient wind or engine power for more than a flop off the end of the launch rail. The day long event rather falls apart after this....."
It would appear that the aircraft was indeed the Wright Experience's 1903 replica air-frame and engine pointed out by megan.
It was quite a rainy day at Kitty Hawk on Dec 17th 2003 so the replica's flight demonstration was somewhat delayed.
If I may quote the witness account of the Editor of " Aeroplane" ,writing in the March 2004 issue p.p.26
"In the end the the weather improves marginally and the Flyer is wheeled out, but there is insufficient wind or engine power for more than a flop off the end of the launch rail. The day long event rather falls apart after this....."
I think that this RAeS group is being fair.
NB. "This Paper represents the views of the Historical Group of
the Royal Aeronautical Society. It has not been discussed
outside the Learned Society Board and, as such, it does not
necessarily represent the views of the Society as a whole,
or any other Specialist Group or Committee.
Royal Aeronautical Society copyright."
(Please bear in mind that neither the apparent author of this paper, nor of his references ( e.g. Charles Gibbs Smith ) IIRC appear to have any recognized formal background or qualification whatsoever in aerodynamics, aviation engineering or pilotage)
The contributions toward aviation development have to be weighed against so called "achievements".
We may ( I hope) continue to debate the impact of the Wrights' work in their contribution toward the ongoing development of the aeroplane.
What is not in dispute ( I think ) is that the Wrights undeniably assisted in this process regarding , for example, developing and demonstrating 3 axis control practicability to a wide audience.
Unfortunately none of Whitehead's work can be seen to have demonstrated any input whatsoever toward the development of a practicable aeroplane.
NB. "This Paper represents the views of the Historical Group of
the Royal Aeronautical Society. It has not been discussed
outside the Learned Society Board and, as such, it does not
necessarily represent the views of the Society as a whole,
or any other Specialist Group or Committee.
Royal Aeronautical Society copyright."
(Please bear in mind that neither the apparent author of this paper, nor of his references ( e.g. Charles Gibbs Smith ) IIRC appear to have any recognized formal background or qualification whatsoever in aerodynamics, aviation engineering or pilotage)
The contributions toward aviation development have to be weighed against so called "achievements".
We may ( I hope) continue to debate the impact of the Wrights' work in their contribution toward the ongoing development of the aeroplane.
What is not in dispute ( I think ) is that the Wrights undeniably assisted in this process regarding , for example, developing and demonstrating 3 axis control practicability to a wide audience.
Unfortunately none of Whitehead's work can be seen to have demonstrated any input whatsoever toward the development of a practicable aeroplane.
Last edited by Haraka; 30th Jun 2015 at 19:25.
Joyride, you may need to add Ukita Kokichi to your list...
https://en.wikipedia.org/wiki/Ukita_K%C5%8Dkichi
https://www.google.co.jp/search?q=%E...A&ved=0CCcQsAQ
https://en.wikipedia.org/wiki/Ukita_K%C5%8Dkichi
https://www.google.co.jp/search?q=%E...A&ved=0CCcQsAQ
Unfortunately none of Whitehead's work can be seen to have demonstrated any input whatsoever toward the development of a practicable aeroplane.
If somebody's achievements are to count, then they need to have done what they did in a manner which allows other people to build upon it.
Even the Wrights with their obsessive attempts to protect their intellectual property did publish what they'd done and do things in a way that allowed other people to build upon their efforts - and as such deserve a lot of credit for that.
Incidentally, noting the RAeS disclaimer - the society is generally pretty rigorous about such things. I've published two papers in their Journal of Aeronautical History and the refereeing was rigorous and thorough; technical papers I've published in Aeronautical Journal equally so.
G
boofhead
Without wishing to contribute to further the thread drift initiated by the booted troll, the aileron drag problem was largely overcome by Arthur Hagg in the form of differential ailerons , first used on the De Havilland D.H. 29 Doncaster of 1921. This aircraft was a cantilever monoplane long range transport .
Patent 184,317, of 13 June 1921 in his name, described a simple acute-angle bell-crank arrangement "so that for a given movement of the pilot's control lever the upwardly moving aileron is displaced through a greater angle than the downwardly moving aileron".
This resulted in the drag of the upturned aileron outweighing the other and assisting , instead of counteracting the turn as had been the inherent lateral secondary effect control problem ( warping and ailerons) from the Wrights onward.
Leslie Frise very soon after in patent 194,753 added his ingenious aileron design , which is still widely used, often in association with Hagg's contribution.
(In point of fact Frederick Handley Page had already patented the slotted aileron which also well counteracted aileron drag, but this wasn't taken up with such alacrity initially.)
Without wishing to contribute to further the thread drift initiated by the booted troll, the aileron drag problem was largely overcome by Arthur Hagg in the form of differential ailerons , first used on the De Havilland D.H. 29 Doncaster of 1921. This aircraft was a cantilever monoplane long range transport .
Patent 184,317, of 13 June 1921 in his name, described a simple acute-angle bell-crank arrangement "so that for a given movement of the pilot's control lever the upwardly moving aileron is displaced through a greater angle than the downwardly moving aileron".
This resulted in the drag of the upturned aileron outweighing the other and assisting , instead of counteracting the turn as had been the inherent lateral secondary effect control problem ( warping and ailerons) from the Wrights onward.
Leslie Frise very soon after in patent 194,753 added his ingenious aileron design , which is still widely used, often in association with Hagg's contribution.
(In point of fact Frederick Handley Page had already patented the slotted aileron which also well counteracted aileron drag, but this wasn't taken up with such alacrity initially.)
Last edited by Haraka; 3rd Jul 2015 at 07:47.
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Thread drift or not, I think a good understanding of the various innovative steps in aviation's development is useful and interesting, regardless of who or what nation begat them.
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Silly little things amuse at times. Like kittens and children.
I own a small experimental airplane and it has ailerons that only go down, yet I get very little adverse yaw.
I own a small experimental airplane and it has ailerons that only go down, yet I get very little adverse yaw.
Rather than post a multitude of links I thought I'd post it in its entirety. From "Flight" FEBRUARY 13, 1909
MECHANICAL FLIGHT. By E. STUART BRUCE, M.A.
Otto Lilenthal, that gifted martyr of the air, tells us that in flying machines conception is nothing, construction is little, experiment is everything.
The year of 1908 will be memorable in aeronautical science for its demonstration of the possibility of mechanical flight. Day after day in France and America has been seen the spectacle of men, not holding in their hands an elaborate plan, not standing by some huge winged machine, but flying in the air with a grace equal to the soaring bird. This has been done with a machine not raised by the buoyancy of a gas, but with one that is heavier than the medium in which it travels, and whose sustentation and direction is accomplished by dexterity and skill.
It is, however, not without honour to the British nation, that one of the fundamental principles of the recent experiments was proposed and elucidated by a Briton in 1866. I refer to the important principle of superposed surfaces, advanced in that year by the late F. H. Wenham. He pointed out that the large mono surfaces necessary to carry a man are difficult of control, but that the lifting power of such a surface can be obtained by placing a number of small surfaces above each other. Wenham built flying machines on this principle, with appliances for the use of his own muscular power. He obtained valuable results as to the driving power of his superposed surfaces, but he did not accomplish flight.
It was in 1872 that H. von Helmholtz emphasised the improbability that man would ever be able to drive a flying machine with his own muscular exertions. After his statements there came a period of stagnation in aeronautical research. An all important link was then wanting ; this was the light motor.
It is difficult to say how much aeronautical science owes to two illustrious names—Sir Hiram Maxim and the late 1'rofessor Langley. These two eminent men took up the subject of flight about the same time in the last decade of the last century, and applied to it all scientific knowledge of the time. Sir Hiram Maxim built the largest flying machine that has been constructed. It spread 4,000 sq. ft. of supporting surface, and weighed 8,000 lbs. The screw propellers were no less than 17 ft. in diameter, the width of the blades at the tip being 5 ft. The boiler was 363 h.p. The machine was run upon wheels on a railway line. It was restrained from premature flight by two wooden rails placed on each side above the wheels. But on one occasion the tendency to rise proved too strong for these measures of restraint. The machine burst through the wooden rails and flew for 300 ft. But Sir Hiram Maxim was not ready at that moment to fly further. When the machine took flight steam was shut off, the machine alighted and was damaged in the fall. The wisdom of Sir Hiram Maxim in not allowing the machine to take free flights was most commendable, for at that time the problem of the maintenance of equilibrium and stability was quite unsolved. But what could not be dared with a gigantic machine carrying human passengers, could be dared with an unmanned model. In 1896 Langley's tandem-surfaced model aerodrome had luck with the aerial currents, and flew for more than three-quarters of a mile over the Potomac River. This machine had 70 sq. ft. supporting surface, weighed 72 lbs., and had an engine of one-horse power, weighing 7 lbs. It is well known how in later years, Langley exaggerated his model into a machine which carried a man, and how twice when it was about to be put to the test over water, at the very moment of being launched, it caught in the launching ways and was pulled into the water. It is supposed that grief at not being able to put his work to a practical test hastened his death. But it is doubtful whether Langley's man-lifting aerodrome would have kept its balance had it escaped the clutches of the launching apparatus.
In the light of recent experiments it has been seen that the maintenance of equlibrium and stability demands special contrivances. It was the question of equilibrium which first led Lilienthal in Germany to experiment with what are called gliding machines. These are aeroplanes which are launched from some hillside against the wind, and depend upon gravity for their motive power. In this way the art of balancing can be practised on motor less gliders. With Lilienthal commenced the age of systematic experimental flight. It was Lilienthal who made the great discovery of the driving forward of arched surfaces against the wind. Lilienthal made some 2,000 glides. Sometimes from a height of 30 metres he glided 300 metres.
The underlying principle of maintaining equilibrium in the air has been recognised to be that the centre of pressure should at all times be on the same vertical line as the centre of gravity due to the weight of the apparatus. Lilienthal sought to keep his balance by altering the position of his centre of gravity by movements of his body. But one day he was upset by a side gust and was killed. Pilcher, in England, took up his epoch-making work. With his soaring machines he made some hundred glides, but he also made one too many. One day, in 1899, in attempting to soar from level ground by being towed by horses, his machine broke, and he fell to the ground. He died shortly afterwards, and became a British martyr of the air. It is sad to relate these successive tragedies, but recent accomplishment has fully justified the actions of those who gave their lives for the sake of knowledge and progress.
The experiments of Mr. Octave Chanute, from 1896-1902, form important links in experimental flight. He first introduced the vital principle of making surfaces movable instead of the aviator, and he made use of superposed surfaces. Mr. Chanute had made an exhaustive study of the subject of aerial navigation, evidenced in his book '"Progress in Flying Machines." He estimated aright the value of the researches of Wenham, whose original memoir on superposed surfaces he has described as " classical." He did not hesitate to adopt the principles advocated by Wenham in his own practical machines. He thus afforded an example of the expediency of studying the past as well as the present. As the earth contains hidden treasures unexcavated for centuries, but which from their intrinsic beauty eclipse the decadent specimens of modern handicraft, so, too, the annals of science contain hidden treasures—indispensable principles, which after years of oblivion have to be unearthed into the light of day.
In his multiple-winged machine Mr. Chanute fixed the wings on pivots. They retro-acted and swung horizontally so as to bring the centre of pressure to coincide with a vertical line passing through the centre of gravity. After making 300 glides with this he made a double-decked machine. It consisted of a rectangular bridge truss of wood, braced by steel wires, and carrying aerocurve surfaces arched j^th on the top and bottom booms. An important feature was the rudder in the rear ; it was attached to the machine by an elastic arrangement. The upper and lower surfaces of this rudder were acted upon by the wind gusts, and altered the angle of incidence of the main supporting surfaces. Seven hundred glides were made by Mr. Chanute's assistants with this machine without any accident. In 1902 Mr Chanute devised a triple-decked machine, and in this the surfaces were pivoted to rock, fore and aft, on a stationary pivot.
The work of Mr. Chanute represents important stages in the evolution of the flying machine, but it was reserved to two other geniuses to bring human flight to a point of progress where the prejudicial critic would be for ever silenced. These two geniuses were the Brothers Wright. I will, therefore, speak of their work, beginning with their earliest experiments.
Before essaying practical flight, the Brothers Wright carried out laboratory experiments. It was in 1900 that they first began to experiment with gliding machines at Kitty Hawk, North Carolina. With the comparatively small surfaces (15*3 square metres) they used in that year, they endeavoured to raise the machine by the wind like a kite, but finding that it often blew too strongly for such a system to be practical, in 1901 they abandoned the idea and resorted to gliding flight.
These machines of 1901 had two superposed surfaces, 173 metres apart, each being 67 metres from tip to tip, 2"i3 metres wide, and arched I-I9th. The total supporting surface was 27 square metres. They dispensed with the tail which previous experimenters had considered necessary. Instead they introduced into their machine two vital principles, upon which not only the success of their preliminary gliding experiments has depended, but also their recent ones with their motor-driven aeroplanes. 1. The hinged horizontal rudder in front for controlling the vertical movements of the machine. 2. The warping or flexing of one wing or the other for steering to right or left. Later a vertical rudder was also added for horizontal steering. The combined movements of these devices maintained equilibrium. The importance of the system of torsion of the main carrying surfaces cannot well be over-estimated. We have only to look to nature for its raison d'etre. An instantaneous photograph of a flight of seagulls shows how varied are the flexings of Nature's aeroplanes in their wondrous manoeuvrings to maintain and recover equilibrium.
In the earliest machines of the Brothers Wright the flexing was attained by light strings held in the hands of the operator. In their recent machines a lever controls this as other accessory movements. The frame of the 1901 machine was of spruce wood and steel. With this machine about 100 glides were made from sand mounds, known as the Kill Devil Hills, at angles of 9 degrees to 10 degrees. A feature of those early experiments was the placing of the operator prone upon the gliding machine instead of in an upright position, to secure greater safety in alighting, and to diminish the resistance. This, however, was only a temporary expedient while the Wrights were feeling their way. In the motor-driven aeroplanes the navigator and his companion are comfortably seated. After the experiments of 1901, the Wrights carried on laboratory researches to determine the amount and direction of the pressures produced by the wind upon planes and arched surfaces exposed at various angles of incidence. They discovered that the tables of the air pressures which had been in use were incorrect. Upon the results of these experiments they produced in 1902 a new and larger machine. This had 28*44 square metres of sustaining surfaces. Thus they showed they had attained to the use of surfaces of twice the area that previous experimenters had dared to handle.
An insight into the cautious and scientific methods by which the Wrights have reached their ultimate success is afforded by the tests which this new machine underwent before gliding flight was undertaken with it. The machine was first flown as a kite so that it might be ascertained whether it would soar in a wind having an upward trend of a trifle over 7 degrees. This was the slope of a hill over which the current was flowing. An experiment showed . that the machine would soar under these circumstances whenever the wind was of sufficient force to keep the angle of incidence : between 4 and 8 degrees. Hundreds of successful glides were afterwards made along the full length of this slope, the longest being: 22^ feet and the time 26 sees. Glides were made at angles of \descent of 6 degrees to 7 degrees, and the glider supported 66 kilogs. per horse-power.
The next step was to apply a motor and screw propellers in place of gravity. This was done in 1903, when four flights were made, the first lasting 12 sees., the last 59 sees., when 260 metres were covered at a height of 2 metres.
In 1904, several hundred flights were made, some being circular. All this work was carried on in a secluded spot and unpublished.
In December, 1905, the world was startled by the news that the Brothers Wright had flown for 24J miles in half an hour at a speed of 38 miles an hour. Much more than this at the time the brothers would not say, and for three years the world thirsted for the fuller knowledge only this year revealed. In the interval some went so far as to distrust the statements of the Brothers Wright, but those who, like myself, had had the privilege of correspondence with them from their first experiments, felt the fullest confidence that every statement they had made was fact. This summer at Le Mans, in France, and Fort Myers, in America, Mr. Wilbur Wright and Mr. Orville Wright have demonstrated to the world the veracity of their former statements. At Le Mans, Mr. Wilbur Wright won the world's record of flight—ih. 31m. 25fs. This event was only two days after the news had arrived of the accident to his brother's machine 'in America in which Mr. Orville Wright broke his leg and Lieut. Selfridge was killed. This accident, of necessity, caused a temporary depression. I can myself bear witness as to its momentary depressive effect on an illustrious aeronautical assemblage. Had there not been the brother at Le Mans to vindicate the good character of the Wright machine, the disaster might have been, another of those blows which retard progress. The accomplishment of Mr. Wilbur Wright's great feat at a time when his nerves must have received a severe shock was an example of the competency of the two geniuses who, of all aviators, have most forwarded aerial navigation.
In Wilbur Wright's machine at Le Mans, the two superposed slightly concave surfaces are about 12*50 metres long and 2 metres wide. They are separated by a distance of i"8o metres. At a distance of 3 metres from the main supporting surfaces is the horizontal rudder for controlling the vertical motions. This is composed of two oval superposed planes. At 2 "50 metres in front of the main supporting surfaces is the vertical rudder, composed of two vertical planes.
The 25-h.p. motor is placed on the lower aero-surface. This weighs 90 kilogs. There is no carburettor, the petrol being injected into airlet pipes. At the left of this motor are the two seats, side by side, for the operator and his companion.
The transmission of power to the two propeller-shafts is effected by chains running in guide tubes. The left-hand chain is crossed, ~to give the opposite movement to the propellers. The two wooden propellers at the back of the machine are 2-50 metres in diameter. They have a low rate of revolution—450 revolutions per minute. Perhaps the weakest part of the Wright machine is the material of the propellers—this is wood. To this fact would appear to be due the fatal accident to Mr. Orville Wright's machine in America. As -is well known, Mr. Orville Wright had extended the length of those" propellers. In rotating, one of them struck against a wire, hanging loosely, and was bioken. Had the propeller been made of suitable metal, it would not, probably, have been broken by the impact.
THE area of the sustaining surfaces is 50 square metres. The weight of the whole machine (with aviator) is about 450 kilogs. Levers under the control of the aviator regulate the various functions of the machine, the flexing of the carrying surfaces, the movements of the horizontal rudders, the vertical rudder, &c.
For starting, the machine runs on rollers along a single wooden rail, but when there is no wind the catapult apparatus has often been used. This consists of a skeleton pylon stand ; at the top of this there is a weight attached to a cord passing through a pulley. The free end of the cord is passed through a pulley at the remote end of the line and brought back and attached to the car by a patent catch. When the weight is allowed to fall the machine is shot forward with starting impetus, enabling the flight to commence. The weight is 700 kilogs., and it falls 5 metres.
While the world was waiting for the details of the Wrights' machine, another type of aeroplane machine came into existence in France, which may be described as an unbending type, and which is devoid of the vital principle of movable main surfaces, which would appear to give the Wright machine a great margin of safety in windy weather. The first of these machines was the bird of prey of M. Santos Dumont. Rudely simple was it in its construction. Two box kites for the supporting surface. In the centre is the motor with the screw behind. To attain flight the machine is run upon wheels until a certain speed is attained, when the machine takes flight. Mr. Farman's machine is another example of a machine that does not bend its wings to adapt itself to circumstances, but still we are bound to confess that the feats which Mr. Farman has managed to perform with his machine, which many critics will say is a less perfect type than that of the Brothers Wright, are very much to his credit. Our national sympathies have been very much with Mr. Farman in his experiments, for though they have taken place in France, the experimenter is of British descent.
Amongst the more recent feats of Mr. Farman may be mentioned his town to town journey from Chalons to Rheims. Another example of the same school is M. Delagrange's aeroplane, and this has accomplished no unworthy flights. In fact, at one time, this last summer, M. Delagrange held the officially observed record for duration of flight, 29m. 53$s., until this was greatly surpassed by Mr. Orville Wright.
In practical aeroplane travelling there will be two great difficulties to be overcome, one, starting ; two, stopping in the air. As has been mentioned above, there are at the present time two methods of starting employed, that of the Brothers Wright, who use starting appliances that are independent of the machine, the other that of the French school, who use wheels which are part of the machine itself. There are disadvantages with either method. It would be hardly practical to carry a huge starting catapult, or even rails, on an aeroplane, and the system of running on the ground on wheels to start would not be practicable in a ploughed field, while the speed required would be prohibited on a public road. For this reason, some think that the heliocoptere, or lifting screw flying machine, will have advantages over the aeroplane, as the lifting horizontal screws will enable it to rise from any place at any time, and also endow it with the power of stopping horizontal motion without descending.
Possibly the future flying machine will consist in the combination of the aeroplane and lifting screw systems. In the way of safety there will be undoubtedly an advantage in retaining the aeroplane surface in case of falls, even though it may not be adjusted to support a certain weight., like a parachute. In the case of Mr. Orville Wright's accident, the spread of canvas to some extent retarded the fall. In the opinion of Mr. Orville Wright, had the accident happened higher up in the air he would have been able to right the machine, and glide safely to earth with it.
Concerning the fall of an aeroplane through accident, such as the collapse of a motor, or even the gliding down purposely without motor action when near to ground, I would like to make a suggestion. If arrangements could be devised to suddenly make the sustaining surfaces convex when about to descend, a safe descent would probably be much facilitated. When I take a flat strip of paper and let it fall, in the majority of cases it will fall revolving rapidly, a fact first pointed out by Maxwell and afterwards commented upon by Lord Rayleigh as a fact that has not been completely explained. But if I curve up the ends of this strip very slightly, the strip generally falls to the floor without turning over. If I let the strip fall ten times in succession, it will probably maintain its stability throughout the test. This is, I think, an experiment worth a practical test.
While on the question of means of securing safety, in may perhaps be suggested that in experimental flights it would be advisable if the operator and his companions provided themselves with parachutes, which probably in the future will come to be regarded as the lifebuoys of flying machines. It would be possible for parachutes to be so suspended that the weight of the aviators suddenly thrown on to them would release them. Probably the best form of parachute will be found to be one with a rotary fall, a principle that has yet to be worked out. The sycamore seed in falling affords an example of a rotarv parachute.
There are some who say that the experiments of the Brothers Wright show that the conquest of the air is complete. But those who speak thus grasp not the situation. It is true that the Brothers Wright have, this year, shown that mechanical flight is possible in a calm atmosphere, and in slight breezes, and this is in itself a triumph. But before we can say man has mastered the great problem of flight, he must fly not only in tranquil airs and slight breezes, but against strong winds and treacherous gusts. Then only will he have wrested from the sea-gulls their long-guarded secret, when, like them, he can use the swift moving air currents to aid his flight. When the aeroplane has encountered the storm, and sailed in its midst undisturbed, and come back sale to port, then, and then only, can he say that, for everyday practical use, the aeroplane has come.
There will, too, be much to be learnt concerning the tricks and ways of aerial currents, even in more tranquil airs. The following simple experiment may suggest how the balance of an aeroplane may be unexpectedly upset by an uprising current of air.
When the wind blows against a cliff or steep hill there is produced an upward current of air. Now imagine an aeroplane comfortably travelling and maintaining its equilibrium and stability. When it reaches the region of the cliff and the sudden uprising current, there will be a great chance of its equilibrium or stability being upset.
In view of the possibility of man acquiring, like soaring birds, the power of making use of the vertical component of the wind, the internal work of the wind, i.e., its gustiness, and even the non uniformity of wind, i.e., its different velocities at different levels, it would seem important that every light that can be thrown upon the difficult subject of equilibrium and stability, experimentally and mathematically, should be eagerly sought. In connection with the subject of " longitudinal stability," I should like to call special attention to the remarkable researches of Professor G. H. Bryan and Mr. W. E. Williams.
In the course of a few remarks on gliding flight which Professor Bryan made in the course of a Friday evening discourse at the Royal Institution in 1901, it seemed to me evident that he had a greater grasp of the mathematical side of the problem of aerial navigation than had been previously evidenced, and, at my request, he wrote the remarkable mathematical discourse on the subject which was read before the Aeronautical Society of Great Britain on December 3rd, 1903.
The remarks of Professor Bryan as to the distinction between equilibrium and stability—a distinction not very generally appreciated— may perhaps with advantage be here quoted :—
" We say that the motion of a flying machine is steady when the resultant velocity is constant in direction and magnitude, and when the angle of the machine to the horizontal is constant. If this motion is slightly disturbed, the machine may either return after a time to the original motion, or it may take up a new and altogether different mode of motion. In the first case, the steady motion is said to be stable, and the second unstable.
" I t is evidently necessary for steady motion of any kind that there should be equilibrium—i.e., that there should be no forces acting on the machine (apart from accidental disturbances) which tend to vary the motion, and hence it follows that the number of modes of steady motion of which a mrchine is capable is, in general, limited, and that when an unstable, steady motion is disturbed, the new mode of motion taken up is entirely different from the old.
" It is necessary to distinguish carefully between equilibrium and stability, as the two are very often confused together. Equilibrium is necessary to secure the existence of a mode of steady motion, but is not sufficient to ensure the stability of the motion.
" The question of the stability of a rigid body moving under the action of any forces has been solved by Routh. In order to apply his results to the stability of flying machines, it is necessary to know the moment of inertia of the machine about its centre of gravity, the resistance of the air on the supporting surfaces as a function of the velocity and angle of incidence, and also the point of application of this force, i.e., the centre of pressure for different angles of incidence. If these are known for the surfaces constituting any machine, then the problem of its stability for small oscillations can be completely solved. Unfortunately, our knowledge of these points is very unsatisfactory. Several valuable series of experiments have been made to determine the resistance on planes, but there is still some doubt as to the position of the centre of pressure at small angles of incidence, especially for oblong planes, and very little indeed is known as to the movement of the centre of pressure on concave surfaces. Until experiments are made on this point it will be impossible to solve the problem of stability for machines supported on concave surfaces."
The last words of Professor Bryan emphasise the necessity of laboratory research, as well as continuing cur experiments in the open. Regarding experiments as to the movement of the centre of pressure on concave surfaces, it may be hoped that when the Brothers Wright publish the full results of their own laboratory researches, light on this subject will be forthcoming.
The photographs of the paths of aerial gliders taken by Professor Bryan and Mr. W. E. Williams are suggestive of the utility of further photographic research on a larger scale. These photographs were taken by attaching magnesium wire to small gliders, consisting of square planes and pairs of square planes, and allowing them to descend in front of a camera in a dark room with the wire burning. By placing a rotating wheel in front of the camera, a dotted instead of a continuous track was obtained, enabling the velocities at different points to be compared. When the path is nearly straight two sets of oscillations are observed. If either of these oscillations increases as the glider descends, the glider will be longitudinally unstable.
With regard to the equilibrium and stability problem, we have not yet got quite beyond the utility of observations with gliding models in the open. There is much yet that might be learnt as to the behaviour of various forms of sustaining surfaces. An instance of very successful and instructive glides (with models) was afforded on the occasion of the kite display, at Sunningdale, in 1907, the experimenter being Mr. Jose Weiss. His demonstration of the possibility of the maintenance of balance for a considerable distance, with a model launched from a hill-top, was one that should encourage himself and others in further research into the difficult problems of soaring flight. He exhibited three model gliders, having wing areas of 3-6, 8'4, and 12'8 sq. ft., with total weights of i\ lbs. and 15 lbs. respectively, the lead ballast in each case representing about two-thirds of the total weight. When launched from the highest hillock available the best glides obtained were some 200 yards in length, with drops from 30 to 50 ft. The small model, raised some 200 ft. by a large kite, and released from that height, righted itself instantly in each case, and gave some very fine glides, the longest being about 600 yards. Some further comparative tests of this description might prove useful. Professor Bryan has suggested that model flying machines might advantageously be fitted with instruments to register stability.
MECHANICAL FLIGHT. By E. STUART BRUCE, M.A.
Otto Lilenthal, that gifted martyr of the air, tells us that in flying machines conception is nothing, construction is little, experiment is everything.
The year of 1908 will be memorable in aeronautical science for its demonstration of the possibility of mechanical flight. Day after day in France and America has been seen the spectacle of men, not holding in their hands an elaborate plan, not standing by some huge winged machine, but flying in the air with a grace equal to the soaring bird. This has been done with a machine not raised by the buoyancy of a gas, but with one that is heavier than the medium in which it travels, and whose sustentation and direction is accomplished by dexterity and skill.
It is, however, not without honour to the British nation, that one of the fundamental principles of the recent experiments was proposed and elucidated by a Briton in 1866. I refer to the important principle of superposed surfaces, advanced in that year by the late F. H. Wenham. He pointed out that the large mono surfaces necessary to carry a man are difficult of control, but that the lifting power of such a surface can be obtained by placing a number of small surfaces above each other. Wenham built flying machines on this principle, with appliances for the use of his own muscular power. He obtained valuable results as to the driving power of his superposed surfaces, but he did not accomplish flight.
It was in 1872 that H. von Helmholtz emphasised the improbability that man would ever be able to drive a flying machine with his own muscular exertions. After his statements there came a period of stagnation in aeronautical research. An all important link was then wanting ; this was the light motor.
It is difficult to say how much aeronautical science owes to two illustrious names—Sir Hiram Maxim and the late 1'rofessor Langley. These two eminent men took up the subject of flight about the same time in the last decade of the last century, and applied to it all scientific knowledge of the time. Sir Hiram Maxim built the largest flying machine that has been constructed. It spread 4,000 sq. ft. of supporting surface, and weighed 8,000 lbs. The screw propellers were no less than 17 ft. in diameter, the width of the blades at the tip being 5 ft. The boiler was 363 h.p. The machine was run upon wheels on a railway line. It was restrained from premature flight by two wooden rails placed on each side above the wheels. But on one occasion the tendency to rise proved too strong for these measures of restraint. The machine burst through the wooden rails and flew for 300 ft. But Sir Hiram Maxim was not ready at that moment to fly further. When the machine took flight steam was shut off, the machine alighted and was damaged in the fall. The wisdom of Sir Hiram Maxim in not allowing the machine to take free flights was most commendable, for at that time the problem of the maintenance of equilibrium and stability was quite unsolved. But what could not be dared with a gigantic machine carrying human passengers, could be dared with an unmanned model. In 1896 Langley's tandem-surfaced model aerodrome had luck with the aerial currents, and flew for more than three-quarters of a mile over the Potomac River. This machine had 70 sq. ft. supporting surface, weighed 72 lbs., and had an engine of one-horse power, weighing 7 lbs. It is well known how in later years, Langley exaggerated his model into a machine which carried a man, and how twice when it was about to be put to the test over water, at the very moment of being launched, it caught in the launching ways and was pulled into the water. It is supposed that grief at not being able to put his work to a practical test hastened his death. But it is doubtful whether Langley's man-lifting aerodrome would have kept its balance had it escaped the clutches of the launching apparatus.
In the light of recent experiments it has been seen that the maintenance of equlibrium and stability demands special contrivances. It was the question of equilibrium which first led Lilienthal in Germany to experiment with what are called gliding machines. These are aeroplanes which are launched from some hillside against the wind, and depend upon gravity for their motive power. In this way the art of balancing can be practised on motor less gliders. With Lilienthal commenced the age of systematic experimental flight. It was Lilienthal who made the great discovery of the driving forward of arched surfaces against the wind. Lilienthal made some 2,000 glides. Sometimes from a height of 30 metres he glided 300 metres.
The underlying principle of maintaining equilibrium in the air has been recognised to be that the centre of pressure should at all times be on the same vertical line as the centre of gravity due to the weight of the apparatus. Lilienthal sought to keep his balance by altering the position of his centre of gravity by movements of his body. But one day he was upset by a side gust and was killed. Pilcher, in England, took up his epoch-making work. With his soaring machines he made some hundred glides, but he also made one too many. One day, in 1899, in attempting to soar from level ground by being towed by horses, his machine broke, and he fell to the ground. He died shortly afterwards, and became a British martyr of the air. It is sad to relate these successive tragedies, but recent accomplishment has fully justified the actions of those who gave their lives for the sake of knowledge and progress.
The experiments of Mr. Octave Chanute, from 1896-1902, form important links in experimental flight. He first introduced the vital principle of making surfaces movable instead of the aviator, and he made use of superposed surfaces. Mr. Chanute had made an exhaustive study of the subject of aerial navigation, evidenced in his book '"Progress in Flying Machines." He estimated aright the value of the researches of Wenham, whose original memoir on superposed surfaces he has described as " classical." He did not hesitate to adopt the principles advocated by Wenham in his own practical machines. He thus afforded an example of the expediency of studying the past as well as the present. As the earth contains hidden treasures unexcavated for centuries, but which from their intrinsic beauty eclipse the decadent specimens of modern handicraft, so, too, the annals of science contain hidden treasures—indispensable principles, which after years of oblivion have to be unearthed into the light of day.
In his multiple-winged machine Mr. Chanute fixed the wings on pivots. They retro-acted and swung horizontally so as to bring the centre of pressure to coincide with a vertical line passing through the centre of gravity. After making 300 glides with this he made a double-decked machine. It consisted of a rectangular bridge truss of wood, braced by steel wires, and carrying aerocurve surfaces arched j^th on the top and bottom booms. An important feature was the rudder in the rear ; it was attached to the machine by an elastic arrangement. The upper and lower surfaces of this rudder were acted upon by the wind gusts, and altered the angle of incidence of the main supporting surfaces. Seven hundred glides were made by Mr. Chanute's assistants with this machine without any accident. In 1902 Mr Chanute devised a triple-decked machine, and in this the surfaces were pivoted to rock, fore and aft, on a stationary pivot.
The work of Mr. Chanute represents important stages in the evolution of the flying machine, but it was reserved to two other geniuses to bring human flight to a point of progress where the prejudicial critic would be for ever silenced. These two geniuses were the Brothers Wright. I will, therefore, speak of their work, beginning with their earliest experiments.
Before essaying practical flight, the Brothers Wright carried out laboratory experiments. It was in 1900 that they first began to experiment with gliding machines at Kitty Hawk, North Carolina. With the comparatively small surfaces (15*3 square metres) they used in that year, they endeavoured to raise the machine by the wind like a kite, but finding that it often blew too strongly for such a system to be practical, in 1901 they abandoned the idea and resorted to gliding flight.
These machines of 1901 had two superposed surfaces, 173 metres apart, each being 67 metres from tip to tip, 2"i3 metres wide, and arched I-I9th. The total supporting surface was 27 square metres. They dispensed with the tail which previous experimenters had considered necessary. Instead they introduced into their machine two vital principles, upon which not only the success of their preliminary gliding experiments has depended, but also their recent ones with their motor-driven aeroplanes. 1. The hinged horizontal rudder in front for controlling the vertical movements of the machine. 2. The warping or flexing of one wing or the other for steering to right or left. Later a vertical rudder was also added for horizontal steering. The combined movements of these devices maintained equilibrium. The importance of the system of torsion of the main carrying surfaces cannot well be over-estimated. We have only to look to nature for its raison d'etre. An instantaneous photograph of a flight of seagulls shows how varied are the flexings of Nature's aeroplanes in their wondrous manoeuvrings to maintain and recover equilibrium.
In the earliest machines of the Brothers Wright the flexing was attained by light strings held in the hands of the operator. In their recent machines a lever controls this as other accessory movements. The frame of the 1901 machine was of spruce wood and steel. With this machine about 100 glides were made from sand mounds, known as the Kill Devil Hills, at angles of 9 degrees to 10 degrees. A feature of those early experiments was the placing of the operator prone upon the gliding machine instead of in an upright position, to secure greater safety in alighting, and to diminish the resistance. This, however, was only a temporary expedient while the Wrights were feeling their way. In the motor-driven aeroplanes the navigator and his companion are comfortably seated. After the experiments of 1901, the Wrights carried on laboratory researches to determine the amount and direction of the pressures produced by the wind upon planes and arched surfaces exposed at various angles of incidence. They discovered that the tables of the air pressures which had been in use were incorrect. Upon the results of these experiments they produced in 1902 a new and larger machine. This had 28*44 square metres of sustaining surfaces. Thus they showed they had attained to the use of surfaces of twice the area that previous experimenters had dared to handle.
An insight into the cautious and scientific methods by which the Wrights have reached their ultimate success is afforded by the tests which this new machine underwent before gliding flight was undertaken with it. The machine was first flown as a kite so that it might be ascertained whether it would soar in a wind having an upward trend of a trifle over 7 degrees. This was the slope of a hill over which the current was flowing. An experiment showed . that the machine would soar under these circumstances whenever the wind was of sufficient force to keep the angle of incidence : between 4 and 8 degrees. Hundreds of successful glides were afterwards made along the full length of this slope, the longest being: 22^ feet and the time 26 sees. Glides were made at angles of \descent of 6 degrees to 7 degrees, and the glider supported 66 kilogs. per horse-power.
The next step was to apply a motor and screw propellers in place of gravity. This was done in 1903, when four flights were made, the first lasting 12 sees., the last 59 sees., when 260 metres were covered at a height of 2 metres.
In 1904, several hundred flights were made, some being circular. All this work was carried on in a secluded spot and unpublished.
In December, 1905, the world was startled by the news that the Brothers Wright had flown for 24J miles in half an hour at a speed of 38 miles an hour. Much more than this at the time the brothers would not say, and for three years the world thirsted for the fuller knowledge only this year revealed. In the interval some went so far as to distrust the statements of the Brothers Wright, but those who, like myself, had had the privilege of correspondence with them from their first experiments, felt the fullest confidence that every statement they had made was fact. This summer at Le Mans, in France, and Fort Myers, in America, Mr. Wilbur Wright and Mr. Orville Wright have demonstrated to the world the veracity of their former statements. At Le Mans, Mr. Wilbur Wright won the world's record of flight—ih. 31m. 25fs. This event was only two days after the news had arrived of the accident to his brother's machine 'in America in which Mr. Orville Wright broke his leg and Lieut. Selfridge was killed. This accident, of necessity, caused a temporary depression. I can myself bear witness as to its momentary depressive effect on an illustrious aeronautical assemblage. Had there not been the brother at Le Mans to vindicate the good character of the Wright machine, the disaster might have been, another of those blows which retard progress. The accomplishment of Mr. Wilbur Wright's great feat at a time when his nerves must have received a severe shock was an example of the competency of the two geniuses who, of all aviators, have most forwarded aerial navigation.
In Wilbur Wright's machine at Le Mans, the two superposed slightly concave surfaces are about 12*50 metres long and 2 metres wide. They are separated by a distance of i"8o metres. At a distance of 3 metres from the main supporting surfaces is the horizontal rudder for controlling the vertical motions. This is composed of two oval superposed planes. At 2 "50 metres in front of the main supporting surfaces is the vertical rudder, composed of two vertical planes.
The 25-h.p. motor is placed on the lower aero-surface. This weighs 90 kilogs. There is no carburettor, the petrol being injected into airlet pipes. At the left of this motor are the two seats, side by side, for the operator and his companion.
The transmission of power to the two propeller-shafts is effected by chains running in guide tubes. The left-hand chain is crossed, ~to give the opposite movement to the propellers. The two wooden propellers at the back of the machine are 2-50 metres in diameter. They have a low rate of revolution—450 revolutions per minute. Perhaps the weakest part of the Wright machine is the material of the propellers—this is wood. To this fact would appear to be due the fatal accident to Mr. Orville Wright's machine in America. As -is well known, Mr. Orville Wright had extended the length of those" propellers. In rotating, one of them struck against a wire, hanging loosely, and was bioken. Had the propeller been made of suitable metal, it would not, probably, have been broken by the impact.
THE area of the sustaining surfaces is 50 square metres. The weight of the whole machine (with aviator) is about 450 kilogs. Levers under the control of the aviator regulate the various functions of the machine, the flexing of the carrying surfaces, the movements of the horizontal rudders, the vertical rudder, &c.
For starting, the machine runs on rollers along a single wooden rail, but when there is no wind the catapult apparatus has often been used. This consists of a skeleton pylon stand ; at the top of this there is a weight attached to a cord passing through a pulley. The free end of the cord is passed through a pulley at the remote end of the line and brought back and attached to the car by a patent catch. When the weight is allowed to fall the machine is shot forward with starting impetus, enabling the flight to commence. The weight is 700 kilogs., and it falls 5 metres.
While the world was waiting for the details of the Wrights' machine, another type of aeroplane machine came into existence in France, which may be described as an unbending type, and which is devoid of the vital principle of movable main surfaces, which would appear to give the Wright machine a great margin of safety in windy weather. The first of these machines was the bird of prey of M. Santos Dumont. Rudely simple was it in its construction. Two box kites for the supporting surface. In the centre is the motor with the screw behind. To attain flight the machine is run upon wheels until a certain speed is attained, when the machine takes flight. Mr. Farman's machine is another example of a machine that does not bend its wings to adapt itself to circumstances, but still we are bound to confess that the feats which Mr. Farman has managed to perform with his machine, which many critics will say is a less perfect type than that of the Brothers Wright, are very much to his credit. Our national sympathies have been very much with Mr. Farman in his experiments, for though they have taken place in France, the experimenter is of British descent.
Amongst the more recent feats of Mr. Farman may be mentioned his town to town journey from Chalons to Rheims. Another example of the same school is M. Delagrange's aeroplane, and this has accomplished no unworthy flights. In fact, at one time, this last summer, M. Delagrange held the officially observed record for duration of flight, 29m. 53$s., until this was greatly surpassed by Mr. Orville Wright.
In practical aeroplane travelling there will be two great difficulties to be overcome, one, starting ; two, stopping in the air. As has been mentioned above, there are at the present time two methods of starting employed, that of the Brothers Wright, who use starting appliances that are independent of the machine, the other that of the French school, who use wheels which are part of the machine itself. There are disadvantages with either method. It would be hardly practical to carry a huge starting catapult, or even rails, on an aeroplane, and the system of running on the ground on wheels to start would not be practicable in a ploughed field, while the speed required would be prohibited on a public road. For this reason, some think that the heliocoptere, or lifting screw flying machine, will have advantages over the aeroplane, as the lifting horizontal screws will enable it to rise from any place at any time, and also endow it with the power of stopping horizontal motion without descending.
Possibly the future flying machine will consist in the combination of the aeroplane and lifting screw systems. In the way of safety there will be undoubtedly an advantage in retaining the aeroplane surface in case of falls, even though it may not be adjusted to support a certain weight., like a parachute. In the case of Mr. Orville Wright's accident, the spread of canvas to some extent retarded the fall. In the opinion of Mr. Orville Wright, had the accident happened higher up in the air he would have been able to right the machine, and glide safely to earth with it.
Concerning the fall of an aeroplane through accident, such as the collapse of a motor, or even the gliding down purposely without motor action when near to ground, I would like to make a suggestion. If arrangements could be devised to suddenly make the sustaining surfaces convex when about to descend, a safe descent would probably be much facilitated. When I take a flat strip of paper and let it fall, in the majority of cases it will fall revolving rapidly, a fact first pointed out by Maxwell and afterwards commented upon by Lord Rayleigh as a fact that has not been completely explained. But if I curve up the ends of this strip very slightly, the strip generally falls to the floor without turning over. If I let the strip fall ten times in succession, it will probably maintain its stability throughout the test. This is, I think, an experiment worth a practical test.
While on the question of means of securing safety, in may perhaps be suggested that in experimental flights it would be advisable if the operator and his companions provided themselves with parachutes, which probably in the future will come to be regarded as the lifebuoys of flying machines. It would be possible for parachutes to be so suspended that the weight of the aviators suddenly thrown on to them would release them. Probably the best form of parachute will be found to be one with a rotary fall, a principle that has yet to be worked out. The sycamore seed in falling affords an example of a rotarv parachute.
There are some who say that the experiments of the Brothers Wright show that the conquest of the air is complete. But those who speak thus grasp not the situation. It is true that the Brothers Wright have, this year, shown that mechanical flight is possible in a calm atmosphere, and in slight breezes, and this is in itself a triumph. But before we can say man has mastered the great problem of flight, he must fly not only in tranquil airs and slight breezes, but against strong winds and treacherous gusts. Then only will he have wrested from the sea-gulls their long-guarded secret, when, like them, he can use the swift moving air currents to aid his flight. When the aeroplane has encountered the storm, and sailed in its midst undisturbed, and come back sale to port, then, and then only, can he say that, for everyday practical use, the aeroplane has come.
There will, too, be much to be learnt concerning the tricks and ways of aerial currents, even in more tranquil airs. The following simple experiment may suggest how the balance of an aeroplane may be unexpectedly upset by an uprising current of air.
When the wind blows against a cliff or steep hill there is produced an upward current of air. Now imagine an aeroplane comfortably travelling and maintaining its equilibrium and stability. When it reaches the region of the cliff and the sudden uprising current, there will be a great chance of its equilibrium or stability being upset.
In view of the possibility of man acquiring, like soaring birds, the power of making use of the vertical component of the wind, the internal work of the wind, i.e., its gustiness, and even the non uniformity of wind, i.e., its different velocities at different levels, it would seem important that every light that can be thrown upon the difficult subject of equilibrium and stability, experimentally and mathematically, should be eagerly sought. In connection with the subject of " longitudinal stability," I should like to call special attention to the remarkable researches of Professor G. H. Bryan and Mr. W. E. Williams.
In the course of a few remarks on gliding flight which Professor Bryan made in the course of a Friday evening discourse at the Royal Institution in 1901, it seemed to me evident that he had a greater grasp of the mathematical side of the problem of aerial navigation than had been previously evidenced, and, at my request, he wrote the remarkable mathematical discourse on the subject which was read before the Aeronautical Society of Great Britain on December 3rd, 1903.
The remarks of Professor Bryan as to the distinction between equilibrium and stability—a distinction not very generally appreciated— may perhaps with advantage be here quoted :—
" We say that the motion of a flying machine is steady when the resultant velocity is constant in direction and magnitude, and when the angle of the machine to the horizontal is constant. If this motion is slightly disturbed, the machine may either return after a time to the original motion, or it may take up a new and altogether different mode of motion. In the first case, the steady motion is said to be stable, and the second unstable.
" I t is evidently necessary for steady motion of any kind that there should be equilibrium—i.e., that there should be no forces acting on the machine (apart from accidental disturbances) which tend to vary the motion, and hence it follows that the number of modes of steady motion of which a mrchine is capable is, in general, limited, and that when an unstable, steady motion is disturbed, the new mode of motion taken up is entirely different from the old.
" It is necessary to distinguish carefully between equilibrium and stability, as the two are very often confused together. Equilibrium is necessary to secure the existence of a mode of steady motion, but is not sufficient to ensure the stability of the motion.
" The question of the stability of a rigid body moving under the action of any forces has been solved by Routh. In order to apply his results to the stability of flying machines, it is necessary to know the moment of inertia of the machine about its centre of gravity, the resistance of the air on the supporting surfaces as a function of the velocity and angle of incidence, and also the point of application of this force, i.e., the centre of pressure for different angles of incidence. If these are known for the surfaces constituting any machine, then the problem of its stability for small oscillations can be completely solved. Unfortunately, our knowledge of these points is very unsatisfactory. Several valuable series of experiments have been made to determine the resistance on planes, but there is still some doubt as to the position of the centre of pressure at small angles of incidence, especially for oblong planes, and very little indeed is known as to the movement of the centre of pressure on concave surfaces. Until experiments are made on this point it will be impossible to solve the problem of stability for machines supported on concave surfaces."
The last words of Professor Bryan emphasise the necessity of laboratory research, as well as continuing cur experiments in the open. Regarding experiments as to the movement of the centre of pressure on concave surfaces, it may be hoped that when the Brothers Wright publish the full results of their own laboratory researches, light on this subject will be forthcoming.
The photographs of the paths of aerial gliders taken by Professor Bryan and Mr. W. E. Williams are suggestive of the utility of further photographic research on a larger scale. These photographs were taken by attaching magnesium wire to small gliders, consisting of square planes and pairs of square planes, and allowing them to descend in front of a camera in a dark room with the wire burning. By placing a rotating wheel in front of the camera, a dotted instead of a continuous track was obtained, enabling the velocities at different points to be compared. When the path is nearly straight two sets of oscillations are observed. If either of these oscillations increases as the glider descends, the glider will be longitudinally unstable.
With regard to the equilibrium and stability problem, we have not yet got quite beyond the utility of observations with gliding models in the open. There is much yet that might be learnt as to the behaviour of various forms of sustaining surfaces. An instance of very successful and instructive glides (with models) was afforded on the occasion of the kite display, at Sunningdale, in 1907, the experimenter being Mr. Jose Weiss. His demonstration of the possibility of the maintenance of balance for a considerable distance, with a model launched from a hill-top, was one that should encourage himself and others in further research into the difficult problems of soaring flight. He exhibited three model gliders, having wing areas of 3-6, 8'4, and 12'8 sq. ft., with total weights of i\ lbs. and 15 lbs. respectively, the lead ballast in each case representing about two-thirds of the total weight. When launched from the highest hillock available the best glides obtained were some 200 yards in length, with drops from 30 to 50 ft. The small model, raised some 200 ft. by a large kite, and released from that height, righted itself instantly in each case, and gave some very fine glides, the longest being about 600 yards. Some further comparative tests of this description might prove useful. Professor Bryan has suggested that model flying machines might advantageously be fitted with instruments to register stability.
In connection with aerial navigation, a line of research, the importance of which cannot well be overestimated, are those investigations which deal with the motions of the medium of travel. Thanks to the indefatigable efforts of Dr. William Napier Shaw, the investigation of the upper air is forming a feature of the work of the Meteorological Office, and most important results have been obtained. Such investigations are all essential for the progress of meteorology ; but they are equally important for the advance of aerial navigation, and their continuance and extension is worthy of the heartiest national support.
It has been said that the ideal flying machine will be attained by a system of automatic stability. Since Mr. Brennan showed how a train could travel on a mono-rail and keep its stability by the application of the gyroscope, a new hope has arisen that the gyroscopic principle may be so applied to flying machines as to render them automatically stable. Simple experiments with the ordinary gyroscopic top shows us that rotary motion can annul the effects of forces other than gravity.
Though we are yet in a stage of experimental flight, and much has to be learnt in theory and practice before it can be adapted to the requirements of daily life, still even in its partially developed state the aeroplane may prove to be a potent factor of war. Under the cogent force of necessity the slenderest threads may have a power that in peace and prosperity would never be accorded them.
I will forebear the discussion of the much vexed question as to whether, when frontiers are obliterated and war made hideously terrible by the flying machine, there will come the end of strife. But at any rate we may hope that the common paths of the air that will unite nations will remove many prejudices and prolong the blest hours of peace.
PS I know there are corrections (proof reading) needed, but it's late and sleep calls.
It has been said that the ideal flying machine will be attained by a system of automatic stability. Since Mr. Brennan showed how a train could travel on a mono-rail and keep its stability by the application of the gyroscope, a new hope has arisen that the gyroscopic principle may be so applied to flying machines as to render them automatically stable. Simple experiments with the ordinary gyroscopic top shows us that rotary motion can annul the effects of forces other than gravity.
Though we are yet in a stage of experimental flight, and much has to be learnt in theory and practice before it can be adapted to the requirements of daily life, still even in its partially developed state the aeroplane may prove to be a potent factor of war. Under the cogent force of necessity the slenderest threads may have a power that in peace and prosperity would never be accorded them.
I will forebear the discussion of the much vexed question as to whether, when frontiers are obliterated and war made hideously terrible by the flying machine, there will come the end of strife. But at any rate we may hope that the common paths of the air that will unite nations will remove many prejudices and prolong the blest hours of peace.
PS I know there are corrections (proof reading) needed, but it's late and sleep calls.