Miscellaneous

The Tellier Two-seat Six-cylinder Monoplane

The Tellier Two-seat Six-cylinder Monoplane at the Paris ShowOne of this type has been sold to the Russian Government(FromAircraft)

Motor weights can be brought down to about two pounds per horse-power, but such extreme lightness is not always needed and may lead to unreliability of operation. The effect of an accumulation of ice, sleet, snow, rain, or dew might be serious in connection with flights in high altitudes or during bad weather. After one of his last year’s flights at Étampes Mr. Farman is said to have descended with an extra load of nearly 200 pounds on this account. With ample motor power, great flexibility in weight sustention is made possible by varying the inclination of the planes. In January of this year, Sommer at Douzy carried six passengers in a large biplane on a cross-country flight: and within the week afterward a monoplane operated by Le Martin flew for five minutes with the aeronaut and seven passengers, at Pau. The total weight lifted was about half a ton, and some of the passengers must have been rather light. The two-passenger Fort Myerbiplane of the Wright brothers is understood to have carried about this total weight. These records have, however, been surpassed since they were noted. Bréguet, at Douai, in a deeply-arched biplane of new design, carriedeleven passengers, the total load being 2602 pounds, and that of aeronaut and passengers alone 1390 pounds. The flight was a short one, at low altitude; but the same aviator last year made a long flight with five passengers, and carried a load of 1262 pounds at 62 miles per hour. And as if in reply to this feat, Sommer carried a live load of 1436 pounds (13 passengers) for nearly a mile, a day or two later, at Mouzon. One feels less certain than formerly, now, in the snap judgment that the heavier-than-air machine will never develop the capacity for heavy loads.

A Monoplane

A Monoplane(FromAircraft)

French aviators are fond of employing a carefully designed car for the operator and control mechanism. The Wright designs practically ignore the car: the aviator sits on the forward edge of the lower plane with his legs hanging over.

It has been found that auxiliary planes must not be too close to the main wings: a gap of a distance about 50% greater than the width of the widest adjacent plane must be maintained if interference with the supporting air currents is to be avoided. Main planes are now always arched; auxiliary planes, not as universally. The concave under surface of supporting wings has its analogy in the wing of the bird and had long years since been applied in the parachute.

Cars and Framework

The car (if used) and all parts of the framework should be of “wind splitter” construction, if useless resistance isto be avoided. The ribs and braces of the frame are of course stronger, weight for weight, in this shape, since a narrow deep beam is always relatively stronger than one of square or round section. Excessive frictional resistance is to be avoided by using a smoothly finished fabric for the wings, and the method of attaching this fabric to the frame should be one that keeps it as flat as possible at all joints.

Some Details

The sketches give the novel details of some machines recently exhibited at the Grand Central Palace in NewYork. The stabilizing planes were invariably found in the rear, in all machines exhibited.

The operator of an aeroplane has to do the work of at least two men. No vessel in water would be allowed to attain such speeds as are common with air craft, unless provided with both pilot and engineer. The aviator is his own pilot and his own engineer. He must both manage his propelling machinery and steer. Separate control for vertical rudders, elevating rudders and ailerons, for starting the engine; the adjustment of the carbureter, the spark, and the throttle to get the best results from the motor; attention to lubrication and constant watchfulness of the water-circulating system: these are a few of the things for him to consider; to say nothing of the laying of his course and the necessary anticipation of wind and altitude conditions.

These things demand great resourcefulness, but—for their best control—involve also no small amount of scientific knowledge. For example, certain adjustments at the motor may considerably increase its power, a possibly necessary increase under critical conditions: but if such adjustments also decrease the motor efficiency there must be a nice analysis of the two effects so that extra power may not be gained at too great a cost in radius of action.

Some Recent French Machines

Some Recent French Machines(FromAircraft)

The whole matter of flight involves both sportsman’s and engineers problems. Wind gusts produce the sameeffects as “turning corners”; or worse—rapidly changing the whole balance of the machines and requiring immediate action at two or three points of control. Both ascent and descent are influenced by complicated laws and are scarcely rendered safe—under present conditions—by the most ample experience. A lateral air current bewilders the steering and also demands special promptness and skill. To avoid disturbing surface winds, even over open country, a minimum flying height of 300 feet is considered necessary. This height, furthermore, gives more choice in the matter of landing ground than a lower elevation.

When complete and automatic balance shall have been attained—as it must be attained—we may expect to see small amateur aeroplanes flying along country roads at low elevations—perhaps with a guiding wheel actually in contact with the ground. They will cost far less than even a small automobile, and the expense for upkeep will be infinitely less. The grasshopper will have become a water-spider.

SOME AEROPLANES—SOME ACCOMPLISHMENTS

Orville Wright at Fort Myer, Va., 1908

The First Balloon Flight Across the British Channel

The First Balloon Flight Across the British ChannelMore than a century before Blériot’s feat, Blanchard crossed from Dover to Calais

The Wright biplane has already been shown (see pages31,37,121,122). It was distinguished by the absence of a wheel frame or car and by the wing-warping method of stabilizing. Later Wright machines have the spring frame and wheels for self-starting. The best known aeroplane of this design was built to meet specifications of the UnitedStates Signal Corps issued in 1907. It was tried out during 1908 at Fort Myer, Va., while one of the Wright brothers was breaking all records in Europe: making over a hundred flights in all, first carrying a passenger and attaining the then highest altitude (360 feet) and greatest distance of flight (seventy-seven miles).

Wright Motor.

Wright Motor.Dimensions in millimeters(From Petit’sHow to Build an Aeroplane)

The ownership of the Wrights in the wing-warpingmethod of control is still the subject of litigation. The French infringers, it is stated, concede priority of application to the Wright firm, but maintain that such publicity was given the device that it was in general use before it was patented.

The Fort Myer machine had sails of forty feet spread, six and one-half feet deep, with front elevating planes three by sixteen feet. It made about forty miles per hour with two passengers. The apparatus was specified to carry a passenger weight of 350 pounds, with fuel for a 125-mile flight. The main planes were six feet apart. The steering rudder (double) was of planes one foot deep and nearly six feet high. The four-cylinder-four-cycle, water-cooled motor developed twenty-five horse-power at 1400 revolutions. The two propellers, eight and one-half feet in diameter, made 400 revolutions.

The flight by Mr. Wilbur Wright from the Statue of Liberty to the tomb of General Grant, in New York, 1909, and the exploits of his brother in the same year, when a new altitude record of 1600 feet was made and H.R.H. the Crown Prince of Germany was taken up as a passenger, are only specimens of the later work done by these pioneers in aerial navigation.

Like the Wrights, the Voisin firm from the beginning adhered firmly to the biplane type of machine. The sketch gives dimensions of one of the early cellular forms built for H. Farman (see illustration, page147). The metal screw makes about a thousand revolutions. Thewings are of india rubber sheeting on an ash frame, the whole frame and car body being of wood, the latter covered with canvas and thirty inches wide by ten feet long. The engine weighed 175 pounds. The whole weight of this machine was nearly 1200 pounds; that built later for Delagrange was brought under a thousand pounds. The ratio of weight to main surface in the Farman aeroplane was about 2-3/4 to 1.

A modified cellular biplane also built for Farman had a main wing area of 560 square feet, the planes being seventy-nine inches wide and only fifty-nine inches apart. The tail was an open box, seventy-nine inches wide and of about ten feet spread. The cellular partitions in this tail were pivoted along the vertical front edges so as to serve as steering rudders. The elevating rudder was in front. The total weight was about the same as that of the first machine and the usual speed twenty-eight miles per hour.

Voisin-Farman Biplane

Henry Farman has been flying publicly since 1907. Hemade the first circular flight of one kilometer, and attained a speed of about a mile a minute, in the year following. In 1909 he accomplished a trip of nearly 150 miles, remaining four hours in the air. Farman was probably the first man to ascend with two passengers.

The Champagne Grand Prize Won by Henry Farman

The Champagne Grand Prize Won by Henry Farman80 Kilometers in 3 hours

Farman's First Biplane at Issy-les-Moulineaux Returning to the Hangar after a Flight

Farman’s First Biplane at Issy-les-Moulineaux Returning to the Hangar after a Flight

TheJune Bug, one of the first Curtiss machines, is shown below. This was one of the lightest of biplanes, having a wing spread of forty-two feet and an area of 370 square feet. The wings were transversely arched, being furthest apart at the center: an arrangement which has not been continued. It had a box tail, with a steering rudder of about six square feet area,abovethe tail. The horizontal rudder, in front, had a surface of twenty square feet. Four triangular ailerons were used for stability. The machine had a landing frame and wheels, made about forty miles per hour, and weighed, in operation, 650 pounds.

The 'June Bug'

The “June Bug”

Mr. Curtiss first attained prominence in aviation circles by winning theScientific Americancup by his flight at the speed of fifty-seven miles per hour, in 1908. In the following year he exhibited intricate curved flights at Mineola, and circled Governor’s Island in New Yorkharbor. In 1910 he made his famous flight from Albany to New York, stoppingen route, as prearranged. At Atlantic City he flew fifty miles over salt water. A flight of seventy miles over Lake Erie was accomplished in September of the same year, the return trip being made the following day. On January 26, 1911, Curtiss repeatedly ascended and descended, with the aid of hydroplanes, in San Diego bay, California: perhaps one of the most important of recent achievements. It is understood that Mr. Curtiss is now attempting to duplicate some of these performances under the high-altitude conditions of Great Salt Lake. According to press reports, he has been invitedto give a similar demonstration before the German naval authorities at Kiel.

Curtis Biplane

(Photo by Levick, N.Y.)

Curtis Biplane

Curtiss' Hydro-Aeroplane at San Diego Getting under Way

Curtiss’ Hydro-Aeroplane at San Diego Getting under Way(From theColumbian Magazine)

Theaeroscapheof Ravard was a machine designed to move either on water or in air. It was an aeroplane with pontoons or floaters. The supporting surface aggregated 400 square feet, and the gross weight was about 1100 pounds. A fifty horse-power Gnome seven-cylinder motor at 1200 revolutions drove two propellers of eight and ten and one-half feet diameter respectively: the propellersbeing mounted one behind the other on the same shaft.

Flying over the Water at Fifty Miles per Hour

Flying over the Water at Fifty Miles per HourCurtiss at San Diego Bay(From theColumbian Magazine)

Ely’s great shore-to-warship flight was made without the aid of the pontoons which he carried. Ropes were stretched across the landing platform, running over sheaves and made fast to heavy sand bags. As a further precaution, a canvas barrier was stretched across the forward end of the platform. The descent brought the machine to the platform at a distance of forty feet from the upper end: grappling hooks hanging from the framework of the aeroplane then caught the weighted ropes, and the speed was checked (within about sixty feet) so gradually that “not a wire or bolt of the biplane was injured.”

Blériot-Voisin Cellular Biplane with Pontoons

Blériot-Voisin Cellular Biplane with PontoonsHauled by a Motor Boat

Latham's 'Antoinette'

Latham’s “Antoinette”

James J. Ward at Lewiston Fair, Idaho

James J. Ward at Lewiston Fair, IdahoFlying Machine Mfg. Co. Biplane (30 hp. Motor)

Marcel Penot in the Mohawk Biplane

Marcel Penot in the Mohawk BiplaneMineola to Hicksville, L. I.26 miles cross-country in 30 minutes (50 hp. Harriman Engine)

Recent combinations of aeroplane and automobile, and aeroplane with motor boat, have been exhibited. One of the latter devices is like any monoplane, except that the lower part is a water-tight aluminum boat body carrying three passengers. It is expected to start of itself from the water and to fly at a low height like a flying fish at a speed of about seventy-five miles per hour. Should anything go wrong, it is capable of floating on the water.

In the San Diego Curtiss flights, the machine skimmed along the surface of the bay, then rose to a height of a hundred feet, moved about two miles through the air in a circular course, and finally alighted close to its starting-point in the water. Turns were made in water as well as in air, a speed of forty miles per hour being attained while “skimming.” The “hydroplanes” used are rigid flat surfaces which utilize the pressure of the water for sustention, just as the main wings utilize air pressure. On account of the great density of water, no great amount of surface is required: but it must be so distributed as to balance the machine. The use of pontoons makes it possible to rest upon the water and to start from rest. A trip like Ely’s could be made without a landing platform, with this type of machine; the aeroplane could either remain alongside the war vessel or be hoisted aboard until ready to venture away again.

There are various other biplanes attracting public attention in this country. In France the tendency is all towardthe monoplane form, and many of the “records” have, during the past couple of years, passed from the former to the latter type of machine. The monoplane is simpler and usually cheaper. The biplane may be designed forgreater economy in weight and power. Farman has lately experimented with the monoplane type of machine: the large number of French designs in this class discourages any attempt at complete description.

Santos-Dumont's 'Demoiselle'

Santos-Dumont’s “Demoiselle”

The smallest of aeroplanes is the Santos-DumontDemoiselle. The original machine is said to have supported 260 pounds on 100 square feet of area, making a speed of sixty miles per hour. Its proprietor was the first aviator in Europe of the heavier-than-air class. After having done pioneer work with dirigible balloons, he won the Deutsch prize for a hundred meter aeroplane flight (the first outside of the United States) in 1906; the speed being twenty-three miles per hour. His first flight, of 400 feet, in a monoplane was made in 1907.

Blériot Monoplane

The master of the monoplane has been Louis Blériot. Starting in 1907 with short flights in a Langley type ofmachine, he made his celebrated cross-country run, and the first circling flights ever achieved in a monoplane, the following year. On July 25, 1909, he crossed the British Channel, thirty-two miles, in thirty-seven minutes.

Latham's Fall into the Channel

Latham’s Fall into the Channel

The Channel crossing has become a favorite feat. Mr.Latham, only two days after Blériot, all but completed it in his Antoinette monoplane. De Lesseps, in a Blériot machine, was more fortunate. Sopwith, last year, won the de Forest prize of $20,000 by a flight of 174 miles from England into Belgium. The ill-fated Rolls made the round trip between England and France. Grace, contesting for the same prize, reached Belgium, was driven back to Calais, started on the return voyage, and vanished—all save some few doubtful relics lately found. Moisant reached London from Paris—the first trip on record between these cities without change of conveyance: and one which has just been duplicated by Pierre Prier, who, on April 12, made the London to Paris journey, 290 miles, in 236 minutes, without a stop. This does not, however, make the record for a continuous flight: which was attained by Tabuteau, who at Buc, on Dec. 30, 1910, flew around the aerodrome for 465 minutes at the speed of 48-1/2 miles per hour.

Other famous crossings include those of the Irish Sea, 52 miles, by Loraine; Long Island Sound, 25 miles, by Harmon; and Lake Geneva, 40 miles, by Defaux.

It was just about a century ago that Cayley first described a soaring machine, heavier than air, of a form remarkably similar to that of the modern aeroplane. Aside from Henson’s unsuccessful attempt to build such a machine, in 1842, and Wenham’s first gliding experiments with a triplane in 1857, soaring flight made no real progress until Langley’s experiments. That investigator, with Maxim and others, ascertained those laws of aerial sustention the application of which led to success in 1903.

De Lesseps in a Blériot Crossing the Channel

(Photo by Levick, N.Y.)

De Lesseps in a Blériot Crossing the Channel

The eight years since have held the crowded hours of aviation. Before this book is printed, it may be rendered obsolete by new developments. The exploits of Paulhan, of R. E. Peltèrie since 1907, Bell’s work with his tetrahedral kites—all have been either stimulating or directly fruitful. Delagrange began to break speed records in 1908. A year later he attained a speed of fifty miles. The first woman to enjoy an aeroplane voyage was Mme. Delagrange, in Turin, in 1908.

The Maxim Aeroplane

Langley's Aeroplane (1896)

Langley’s Aeroplane (1896)Steam driven

The first flight in England by an English-built machine was made in January, 1909. That year, Count de Lambert flew over Paris, and in 1910 Grahame-White circled his machine over the city of Boston. The year 1910 surpassedall its predecessors in increasing the range and control of aeroplanes; over 1500 ascents were made by Wright machines alone; but 1911 promises to show even greater results. Three men made cross-country flights from Belmont Park to the Statue of Liberty and back, in New York;2at least five men attained altitudes exceeding 9,000 feet. Hamilton made the run from New York to Philadelphia and return, in June. The unfortunate Chavez all but abolished the fames of Hannibal and Napoleonby crossing the icy barrier of the Alps, from Switzerland to Italy—in forty minutes!

Robart Monoplane.

Tabuteau, almost on New Year’s eve, broke all distance records by a flight of 363 miles in less than eight hours; while Barrier at Memphis probably reached a speed of eighty-eight miles per hour (timing unofficial). With the new year came reports of inconceivable speeds by a machine skidding along the ice of Lake Erie; the successful receipt by Willard and McCurdy of wireless messages from the earth to their aeroplanes; and the proposal by the United States Signal Corps for the use of flying machines for carrying Alaskan mails.

Vina Monoplane.

McCurdy all but succeeded in his attempt to fly from Key West to Havana, surpassing previous records by remaining aloft above salt water while traveling eighty miles. Lieutenant Bague, in March, started from Antibes, near Nice, for Corsica. After a 124-mile flight, breaking all records for sea journeys by air, he reached the islet of Gorgona,near Leghorn, Italy, landing on bad ground and badly damaging his machine. The time of flight was 5-1/2 hours. Bellinger completed the 500-mile “accommodation train” flight from Vincennes to Pau; Vedrine, on April 12, by making the same journey in 415 minutes of actual flying time, won the Béarn prize of $4000; Say attained a speed of 74 miles per hour in circular flights at Issy-les-Moulineaux. Aeroplane flights have been made in Japan, India, Peru, and China.

One of the most spectacular of recent achievements is that of Renaux, competing for the Michelin Grand Prize. A purse of $20,000 was offered in 1909 by M. Michelin, the French tire manufacturer, for the first successful flight from Paris to Clermont-Ferrand—260 miles—in less than six hours. The prize was to stand for ten years. It was prescribed that the aviator must, at the end of the journey, circle the tower of the Cathedral and alight on the summit of the Puy de Dome—elevation 4500 feet—on a landing place measuring only 40 by 100 yards, surrounded by broken and rugged ground and usually obscured by fog.

The flight was attempted last year by Weymann, who fell short of the goal by only a few miles. Leon Morane met with a serious accident, a little later, while attempting the trip with his brother as a passenger. Renaux completed the journey with ease in his Farman biplane, carrying a passenger, his time being 308 minutes.

This Michelin Grand Prize is not to be confused with theMichelin Trophy of $4000 offered yearly for the longest flight in a closed circuit.

Speeds have increased 50% during the past year; even with passengers, machines have moved more than a mile a minute: average motor capacities have been doubled or tripled. The French men and machines hold the records for speed, duration, distance, and (perhaps) altitude. The highest altitude claimed is probably that attained by Garros at Mexico City, early this year—12,052 feet above sea level. The world’s speed record for a two-man flight appears to be that of Foulois and Parmalee, made at Laredo, Texas, March 3, 1911: 106 miles, cross-country, in 127 minutes. Three-fourths of all flights made up to this time have been made in France—a fair proportion, however, in American machines.

NOTE

The rapidity with which history is made in aeronautics is forcibly suggested by the revision of text made necessary by recent news. The newDeutschlandhas met the fate of its predecessors; the Paris-Rome-Turin flight is at this moment under way; and Lieutenant Bayne, attempting once more his France-to-Corsica flight, has—for the time being at least—disappeared.

THE POSSIBILITIES IN AVIATION

Men now fly and will probably keep on flying; but aviation is still too hazardous to become the popular sport of the average man. The overwhelmingly important problem with the aeroplane is that of stability. These machines must have a better lateral balance when turning corners or when subjected to wind gusts: and the balance must be automatically, not manually, produced.

Blanc Monoplane

Other necessary improvements are of minor urgency and in some cases will be easy to accomplish. Better mechanical construction, especially in the details of attachments, needs only persistence and common sense. Structural strength will be increased; the wide spread of wing presents difficulties here, which may be solved either byincreasing the number of superimposed surfaces, as in triplanes, or in some other manner. Greater carrying capacity—two men instead of one—may be insisted upon: and this leads to the difficult question of motor weights. The revolving air-cooled motor may offer further possibilities: the two-cycle idea will help if a short radius of action is permissible: but a weight of less than two pounds tothe horse-power seems to imply, almost essentially, a lack of ruggedness and surety of operation. A promising field for investigation is in the direction of increasing propeller efficiencies. If such an increase can be effected, the whole of the power difficulty will be greatly simplified.

Melvin Vaniman Triplane

Jean de Crawhez Triplane

A Triplane

This same motor question controls the proposal for increased speed. The use of a reserve motor would again increase weights; though not necessarily in proportion to the aggregate engine capacity. Perhaps something may be accomplished with a gasoline turbine, when one is developed. In any case, no sudden increase in speeds seems to be probable; any further lightening of motors must be undertaken with deliberation and science. If much higher maximum speeds are attained, there will be an opportunity to vary the speed to suit the requirements. Then clutches, gears, brakes, and speed-changing devices of various sorts will become necessary, and the problem of weights of journal bearings—already no small matter—will be made still more serious. And with variable speed must probably come variable sail area—in preference to tilting—so that the fabric must be reefed on its frame. Certainly two men, it would seem, will be needed!

Better methods for starting are required. The hydroplane idea promises much in this respect. With a better understanding and control of the conditions associated with successful and safe descent—perhaps with improved appliances therefor—the problem of ascent will also be partly solved. If such result can be achieved, these measures of control must be made automatic.

The building of complete aeroplanes to standard designs would be extremely profitable at present prices, which range from $2500 to $5000. Perhaps the most profitable part would be in the building of the motor. The framingand fabric of an ordinary monoplane could easily be constructed at a cost below $300. The propeller may cost $50 more. The expense for wires, ropes, etc., is trifling; and unless special scientific instruments and accessories are required, all of the rest of the value lies in the motor and its accessories. Within reasonable limits, present costs of motors vary about with the horse-power. The amateur designer must therefore be careful to keep down weight and power unless he proposes to spend money quite freely.

Not very much is being heard of performances of dirigible balloons just at present. They have shown themselves to be lacking in stanchness and effectiveness under reasonable variations of weather. We must have fabrics that are stronger for their weight and more impervious. Envelopes must be so built structurally as to resist deformation at high speeds, without having any greatly increased weight. A cheap way of preparing pure hydrogen gas is to be desired.

Most important of all, the balloon must have a higher speed, to make it truly dirigible. This, with sufficient steering power, will protect it against the destructive accidents that have terminated so many balloon careers. Here again arises the whole question of power in relation to motor weight, though not as formidably as is the case with the aeroplane. The required higher speeds are possible now, at the cost merely of careful structural design,reduced radius of action, and reduced passenger carrying capacity.

Better altitude control will be attained with better fabrics and the use of plane fin surfaces at high speeds. The employment of a vertically-acting propeller as a somewhat wasteful but perhaps finally necessary measure of safety may also be regarded as probable.

Giraudon's Wheel Aeroplane

Giraudon’s Wheel Aeroplane

Theaviplane,ornithoptèreororthopteris a flying machine with bird-like flapping wings, which has received occasional attention from time to time, as the result of a too blind adherence to Nature’s analogies. Every mechanical principle is in favor of the screw as compared with any reciprocating method of propulsion. There have been few actual examples of this type: a model was exhibited at the Grand Central Palace in New York in January of this year.

The mechanism of an orthopter would be relatively complex, and the flapping wings would have to “feather” on their return stroke. The flapping speed would have to be very high or the surface area very great. This last requirement would lead to structural difficulties. Propulsion would not be uniform, unless additional complications were introduced. The machine would be the most difficult of any type to balance. The motion of a bird’s wing is extremely complicated in its details—one that it would be as difficult to imitate in a mechanical device as it would be for us to obtain the structural strength of an eagle’s wing in fabric and metal, with anything like the same extent of surface and limit of weight. According to Pettigrew, the efficiency of bird and insect flight depends largely upon the elasticity of the wing. Chatley gives the ratio of area to weight as varying from fifty (gnat) to one-half (Australian crane) square feet per pound. The usual ratio in aeroplanes is from one-third to one-half.

About the only advantages perceptible with the orthopter type of machine would be, first, the ability “to start from rest without a preliminary surface glide”; and second, more independence of irregularity in air currents, since the propulsive force is exerted over a greater extent than is that of a screw propeller.

Thegyroplaneorhelicopterwas the type of flying machine regarded by Lord Kelvin as alone likely to survive. It lifts itself by screw propellers acting vertically. This form was suggested in 1852. When only a single screw was used, the whole machine rotated about its vertical axis. It was attempted to offset this by the use of vertical fin-planes: but these led to instability in the presence of irregular air currents. One early form had two oppositely-pitched screws driven by a complete steam engine and boiler plant. One of the Cornu helicopters had adjustable inclined planes under the two large vertically propelling screws. The air which slipped past the screws imposed a pressure on the inclined planes which was utilized to produce horizontal movement in any desired direction—if the wind was not too adverse. A gasoline engine was carried in a sort of well between the screws.

Bréguet Gyroplane During Construction

Bréguet Gyroplane During Construction(Helicopter type)

The helicopter may be regarded as the limiting type of aeroplane, the sail area being reduced nearly to zero; the wings becoming mere fins, the smaller the better. It therefore requires maximum motor power and is particularly dependent upon the development of an excessively light motor. It is launched and descends under perfect control, without regard to horizontal velocity. It has very little exposed surface and is therefore both easy to steer and independent of wind conditions. By properly arranging the screws it can be amply balanced: but it must have a particularly stout and strong frame.

The development of this machine hinges largely on the propeller. It is not only necessary to developpower(which means force multiplied by velocity) but actualpropulsive verticalforce: and this must exceed or at least equal the whole weight of the machine. From ten to forty pounds of lifting force per horse-power have been actually attained: and with motors weighing less than five pounds there is evidently some margin. The propellers are of special design, usually with very large blades. Four are commonly used: one, so to speak, at each “corner” of the machine. The helicopter is absolutely dependent upon its motors. It cannot descend safely if the power fails. If it is to do anything but ascend and descend it must have additional propulsive machinery for producing horizontal movement.

The aeroplane is thus particularly weak as to stability, launching, and descending: but it is economical in power because it uses the air to hold itself up. The dirigible balloon is lacking in power and speed, but can ascend and descend safely, even if only by wasteful methods; and it can carry heavy weights, which are impossible with the structurally fragile aeroplane. The helicopter is wasteful in power, but is stable and sure in ascending and descending, providing only that the motor power does not fail.

Why, then, not combine the types? An aeroplane-dirigible would be open to only one objection: on the ground of stability. The dirigible-helicopter would have as its only disadvantage a certain wastefulness of power,while the aeroplane-helicopter would seem to have no drawback whatever.

All three combinations have been, or are being, tried. An Italian engineer officer has designed a balloon-aeroplane. The balloon is greatly flattened, or lens-shaped, and floats on its side, presenting its edge to the horizon—if inclination be disregarded. With some inclination, the machine acts like an aeroplane and is partially self-sustaining at any reasonable velocity.

The use of a vertically-acting screw on a dirigible combines the features of that type and the helicopter. This arrangement has also been the subject of design (as in Captain Miller’s flexible balloon) if not of construction. The combination of helicopter and aeroplane seems especially promising: the vertical propellers being employed for starting and descending, as an emergency safety feature and perhaps for aid in stabilizing. The fact that composite types of flying machine have been suggested is perhaps, however, an indication that the ultimate type has not yet been established.

The flying machine will probably become the vehicle of the explorer. If Stanley had been able to use a small high-powered dirigible in the search for Livingstone, the journey would have been one of hours as compared with months, the food and general comfort of the party would have been equal in quality to those attainable at home,and the expense in money and in human life would have been relatively trifling.

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