AUGUST 1 ^ BULLETIN 19 18 No. 3

Troblems of Aeroplane Improvement

''• •- "•--• ——— -'v

Issued by NAVAL CONSULTING BOARD OF THE UNITED STATES

AND ENGINEERING COUNCILS WAR COMMITTEE OF TECHNICAL SOCIETIES

INDEX: PAGE AEROPLANE MOTIVE POWER IMPROVEMENT Possibilities for Radical Advances 3 Conservative Improvements in Aeroplane Motors, by E. H. Sher- bondy, Airplane Engineering Dept, Bureau of Aircraft Production War Dept 4 PROBLEMS IN AERONAUTICS, by. Dr. W. F. Durand, Scientific Attache American Embassy, Paris, lately Chairman The National Advisory Committee for Aeronautics 11 AIRCRAFT PROBLEMS, by W. B. Stout, Technical Advisor Aircraft Board 16 WORKING BIBLIOGRAPHY For Aeroplane General Design 19 For Aeromotors 28

Examined and Publication Authorized \1 __ f

Secretary of the Navy INTRODUCTION

Many of the greatest improvements in industry have been made by men who had but little practical experience or technical training along the line in question. But they brought to the task the requisites most needed: a free brain, a clear insight and fresh enthusiasm.

Perhaps yours is the mind that will see the way to some great improve­ ment in aircraft, one of the most potent weapons for winning the war. A billion dollars has been set aside for production. The finest shops and the best trained men in the country are working upon design and manufacture and we will soon have machines. But we want the best in the world. The men engaged in the details of the work are just now under a pressure which is not favorable for the exercise of creative powers. Technical men who are far enough from the work to see it in a different perspective, therefore, have a special opportunity for useful service.

In order to save you labor specialists have summarized in the enclosed bulletin the most pressing problems of aircraft improvement and have indicated probable lines of progress. Any help you can give will be welcomed. Inventions and ideas submitted in reply should be addressed to Thomas Robins, Secretary Naval Consulting Board, 15 Park Row, New York.

2 AEROPLANE MOTIVE POWER IMPROVEMENT The present situation with respect to the improvement of aeroplane motive power is that the Government is concentrating all its energies upon the quick production of the best design it has been able ta select from present motor development. For manufacturing reasons it was obviously necessary to standardize this design and just now the Government is not in a position to consider improved motors and systems of power. Such ques­ tions must be deferred if possible until after the pressing needs of the moment have been met. At all times, however, advances which are great enough and which have been sufficiently proven, necessarily command a right of way. Power development is moving so swiftly and there is so much room for its advance that nothing is really fixed, and no nation is taking a chance of overlooking anything which is really worth while. Minor improvements, applicable with the present motor, can be considered at any time if they are of sufficient value. POSSIBILITIES FOR RADICAL ADVANCES For war uses the cost of power is immaterial, the important object being : (1) To secure steady, reliable operation. (2) To obtain lighter weights than the 2 to 2.5 lbs. per H. P. now at­ tained. (1.75 lbs. without radiator, water, piping, propeller, etc.) (3) To obtain more work per pound of fuel carried. The room for improvement is evident from a view of the conditions under which the average aeroplane motor now operates. (Figures approx­ imate) : Energy of fuel delivered by engine shaft to propellor (Thermal efficiency). ITor the Indicated H. P. 30%. For the Brake H. P 25 per ct. Energy consumed by engine friction 5 Energy lost by cooling 30 Energy escaping in exhaust (including that of unbnrned fuel) 40 Total fuel contents 100 Mechanical efficiency of propellor 75 per ct. Net energy of fuel delivered by propellor and available for flight (0.75 x 0.25) 19 per ct. The field for radical improvements is an extremely broad one, covering all the possibilities of new power cycles and of gas turbines. No suggestions can be offered to those who wish to investigate these possibilities, but they can familiarize themselves with the subject through the bibliography at­ tached.

3 CONSERVATIVE IMPROVEMENTS IN AIRPLANE MOTORS By E. H, SUerbondy, V. 8. Airplane Engineering Dept., Bureau of Aircraft Production, War Dept. The following is a brief presentation of some of the problems encoun­ tered by aircraft motor and airplane designers, and also some suggestions relative to the improvement of apparatus and methods of function. It is assumeed that those interested in the development of apparatus required in this field of work are informed as to current progress. Engi­ neers who are familiar with the development of power and general ma­ chinery, but who are without special knowledge of aircraft motors and their accessories are advised to read back issues of the American, English and French periodicals devoted to aeronautics and automobile engineering. They should also look up the subject through the works upon internal com­ bustion engines given in the Bibliography attached, which also includes a list of the periodicals which are of the most importance from a technical standpoint. American books upon aircraft motors are often of an elemen­ tary character unsuitable for the purpose in hand. Much valuable infor­ mation will be found in the journals of Technical Societies mentioned in the Bibliography. The problems to be solved mainly refer to improvements in the motor power apparatus, its specific weight ; its thermal efficiency referred to brake horse-power and the reliability of its mechanical construction". In order to do successful work in any line of invention it is desirable to have a definite idea of what is still to be accomplished and also more or less familiarity with the history of the particular art. Many helpful sug­ gestions may be obtained from a study of experiments on various kinds of apparatus which have failed for reasons which may not be operative now through the existence of better materials and more knowledge or through the advance of the physical sciences and of methods of carrying out the in­ tention of the invention. This point is illustrated by the history of auto­ mobile rear axle drives. For a long time straight bevel gears were used. The helical bevel gear was known many years ago, but no method had been devised by which it could be economically produced, so that it did not come into practical use until about 1912.

4 The present state of the art of designing aircraft motors may be briefly summarized as follows: The engine types are practically standardized. There are two principal types—one having 6 or 8 vertical cylinders all in line; the other being the "V" type with either 8 or 12 cylinders. It should be added that the use of aluminum has increased enormously the possibilities of the radial types of motors in moderate powers, these being designed with either fixed or rotating cylinders and with either air or water cooling. To be useful for aircraft work an engine must not weigh more than 2.4 pounds per brake horse-power (1.7 pounds without radiator, water, piping, propeller, etc.). It must, moreover, be composed of parts which can be readily produced by American manufacturing methods. The thermal efficiency of current types of aircraft motors referred to brake horse-power ranges from 25% to 32%, this being the proportion of the original heat contents of the fuel consumed which appears in shaft horse-power. "While the efficiency of these engines is higher than that of any other type of prime mover, including commer­ cial Diesel engines within the output range of aircraft engines, their econ­ omy is rather low at less than maximum horse-power, and every effort should be made to improve the economy at part load. The economy varies but little for considerable changes in altitude, so that in this matter the effect of altitude is not often of importance. It should be borne in mind that improvements suggested for the pres­ ent system of motor power should lend themselves to development to a prac­ tical stage within a short time, say, six months ; that is, the apparatus should be experimentally proven and ready for production at the end of this period. Elements of the power system susceptible to improvement are dealt with in the following:

Carburetion

For a given motor operating successively at two different altitudes under identical conditions, i. e., at the same speed and with the same car­ buretor adjustment (the same sectional areas for the passage of air, gasoline and mixture), the amounts of air (by weight) drawn into the motor in the same time are proportional to the barometric pressures at the two alti­ tudes. The volume of air drawn in remains the same. Since the density of the gasoline does not vary with the altitude, we may summarize the effect of changes in altitude upon the mixture quality as follows : The richness of the carburetor mixture increases with the altitude. It varies inversely as the square root of the ratio of barometric pressures

5 (assuming the motor speed and throttle position to remain constant). "While this is approximately/correct for ordinary elevations it is decidedly true at altitudes over 15,000 feet. This leads us to a consideration of the subject of carburetor regula­ tion for varying altitude. At present this regulation is effected by means of a device called an altimeter, whose function it is to control the flow of gasoline through the carburetor nozzle. This object may be accomplished either by reducing the size of the orifice through which the liquid flows, or by reducing the equivalent head above the orifice. The equivalent head can be reduced by making the pressure in the float chamber dependent upon the pressure above the carburetor throttle, or by adding more air to the carbureted mixture above the mixing chamber. These functions are carried out automatically in two types of carburetors so far developed. One of these is the product of the Zenith Carburetor Company of Lyons, France. This comprises a barometric capsule which through a linkage operates a valve regulating the pressure in the float chamber. The other was developed by the Panhard-Levassor Company of Paris, France, and in this there is a diaphragm acted upon by the atmospheric pressure and the pressure within the carburetor. The motion of this diaphragm controls an auxiliary air valve above the primary mixing chamber of the carburetor. Like the density, the temperature of the air decreases at high altitudes, but the decrease follows no regular law. Figures showing the actual de­ crease in temperature during several flights up to 20,000 ft. altitude were published in the Journal of the Society of Automotive Engineers for Sep­ tember, 1917. A change in temperature affects the quality of the mixture, since the viscosity of the fuel changes with the temperature, and the quan­ tity flowing through a fixed size orifice varies accordingly. However, varia­ tion of the mixture quality as a result of temperature changes, is very small compared with the variation due to changes in barometric pressure, and the complication of any thermostatic arrangement for correcting the rate of gasoline flow or of air admission might outweigh the practical advantages gained. The value of any such apparatus would depend entirely on the practicability of the form in which it appeared.

Precompression of Air Supply for Motor This is one of the major problems on which aviation motor designers are at present engaged. Apparatus for this purpose must operate reliably and be light in weight ; it must be designed with a view to very high me­ chanical and volumetric efficiency.

6 Ignition This is a most promising field for experimental investigation. Owing to the fact that modern engines develop explosion pressures of from 400 to 600 pounds per square inch and a M. E. P. of 120 to 135 pounds, the problem of spark.plugs is a difficult one. The insulation must be capable of withstanding the enormous tem­ peratures developed, and the plug must not leak. A slight leak past the insulation for a period of 30 seconds would cause complete failure of the plug. The spark points of the plugs must be maintained at a sufficiently high temperature to prevent an accumulation of carbon on them, and yet their temperature must not be high enough to cause pre-ignition of the combustible charge. This means that the spark points must be maintained within a critical temperature zone.- The chief trouble encountered with spark plugs up to date has been that at low engine power the temperature of the spark points is so low that the points rapidly become carbonized and the plug is short circuited. This carbonizing can be corrected by a better system of lubrication. Heating and expansion of the insulated electrode tends to cause the in­ sulator to fail by cracking or otherwise, and the fact that all good electrical insulators are poor conductors of heat makes it difficult to keep the tem­ perature of the insulator down and protect it from injury by overheating. The best minds in this field of activity are now working towards a solution of this pressing problem. References to this subject may be looked up in the Journal of the Societey of Automotive Engineers under the headings of "Ignition" and "Spark Plugs." The generating and distributing ap­ paratus required and the ignition wiring have been developed to a high degree of reliability, and unless some entirely new scheme of ignition can be devised which overcomes the difficulties of the present system, we feel that the jump spark ignition system will maintain its present unique position, having no competitors. Nevertheless, it is to be observed that in reliability the present ignition systems still leave a good deal to be desired. Moreover, the weights are too high, and a larger output of energy per cylinder would simplify the plug problem.

Engine Parts Engine parts of all kinds are generally very reliable, and an analysis of the failures of parts in French aircraft engines during 1915 and 1916, revealed no single part whose failures represented more than 2 per cent, of the total number. Thirty per cent, of the interruptions of power were due to hits by projectiles which affected some portion of the power system.

i Self-Starters Starting systems may be of three kinds—air, electric and powder shell. Air starters and electric starters are usually applied to the motors of sea­ planes, as seaplanes are not required to operate at very great elevations or at very great speeds; so the additional weight of the starting apparatus is not a serious objection, but in reconnaissance and fighting planes the weight must be kept at a minimum in order that speeds of 140 to 180 miles per hour and very great altitudes may be attained. In a few cases air starters have been fitted to aircraft engines mounted in fighting planes. The sys­ tem makes use of an air bottle for supplying the required amount of air under the proper pressure. This air is either led through a distributor to the motor cylinders or is used to operate a multiple cylinder air engine connected with the motor crankshaft by means of an overrunning clutch. At the time of writing, all starting systems have been discarded for battle planes. However, as we in America have developed electric starting systems of rather light weight to a high degree of reliability, these may be fitted to motors mounted in bombing planes, which are usually equipped with multiple motors and do not necessarily have to be of very high speed. The Sheffield Car Company of Michigan has built gasoline railway cars in which the gasoline motor is started by means of a charge of black powder detonated by a special mechanism in the cylinder head, and it is possible that this idea may be developed until'practical results are obtained, although the problem is very difficult in motors with a large number of cylinders.

Exhaust Mufflers Exhaust mufflers would be desirable provided their weight was not ex­ cessive, and they were effective in muffling and proof against injury from excessive heating. Since aircraft motors of today are 200 to 600 shaft horse­ power, and heat is constantly passing out with the exhaust gases at a rate equal to twice the useful power, it is at once apparent that the construction of a suitable muffler for aircraft engines is not a simple problem. An auto­ mobile muffler is called upon to radiate about one-tenth the amount of heat which would pass through the aviation muffler. Experiments in connection with this problem have been carried out at Cornell University, and the results obtained were published in the trade papers. In working out the problem it will be necessary to guard against any interference with the cooling of exhaust valves by radiation and conduction.

8 Cooling Radiators Cooling radiators are one of the most vulnerable points of the modern fighting machine, the system of cooling used being substantially the same as that on automobiles. However, the cooling capacity of a given sized radiator is greatly increased on an airplane by reason of the high speed at which air passes through the tubes. The form of radiator and its location are subjects which are usually left to the plane designer. A radiator may absorb 20 per cent, of the engine power if it is not properly placed or de­ signed for free air flow. A remarkable paper covering the whole subject of engine cooling and radiator design was published in 1916 by F. W. Lan- chester in the proceedings of the Institution of Automobile Engineers, and should be consulted by anyone interested in this subject.

Fuel System Fuel storage and supply systems are by no means satisfactory, and al­ though a great deal of thought and ingenuity have been spent upon the design of these parts, this still remains a fruitful field for suggestion and invention. The arrangement of the fuel tanks and lines, and the method of fitting the fuel tanks to the motors are probably the least settled features of aircraft, construction. A suggestion in this connection isj to make the tanks and fuel lines of some high resistance steel, so as to make them bullet-proof. The objection to this is the great weight entailed, but this might be minimized by the development of special alloys possessing little weight and great strength. Fuel The present type of aircraft engine operates successfully only on gaso­ line having a boiling point not exceeding 250 deg. Fah. Hydro carbon fuels of higher boiling points are apt to crack or become dissociated under the combined action of the high temperature and pressure, with the result that compounds are formed which produce a smoky exhaust. If we could find a fuel which carried the oxygen required for its combustion, the power of aviation motors would be affected neither by the altitude nor the tempera­ ture of the- atmosphere. Propellers The subject of propeller design and construction is an extremely diffi­ cult one, since propellers must operate at enormous speeds in an atmosphere of varying temperature and density, and are subject to very complex stresses. Very important technical papers on the design of propellers have appeared in English and French Aeronautic magazines, and in particular

9 the experiments of G. Eiffel and A. Ghiret, which were published in France are of the first importance. Propeller design and construction have been discussed also in engineering papers in our own journals of aviation.

Machine Gun Synchronizers Machine gun synchronizers originated in France in 1915. Their ob­ ject is to permit of firing a machine gun through the arc between the pro­ peller blades. An important paper dealing with this apparatus was pub­ lished in France in 1916, under the title, "Les Avions Allemands." Li­ brairie Aéronautique, 40 Rue de Seine, 40 Paris. (Copies of this pamphlet may be had from the book dealer Brentano, Fifth Avenue, New York City.)

Instruments Many new instruments have been devised for aircraft. These include barographs, which indicate and record altitude; drift meters, which indi­ cate side slip of the plane through the air; inclinometers, which indicate the angle of the plane; tachometers, which indicate the engine speed; oil, gasoline and water gauges, which indicate the pressure and temperature of these fluids, and, speed indicators, which indicate the speed of the plane relative to the air through which it is traveling. All of these devices are capable of being further improved. Two instruments which it would be very desirable to have would be one giving the speed of the plane relative to the ground and one showing the altitude of the plane above the ground. Pilots flying at night with a barograph know only their altitude above sea level, and as they may not know the character of the ground over which they are flying, when they fly at low elevations (1,000 to 2,000 feet above sea level) they are not at all eertain that they are at a safe altitude. New cycles of operation for heat motors and the improvement of old ones are possible and desirable. The most available cycle, which is sus­ ceptible of immediate practical development, is the two-stroke cycle, and engines of this type have been built in great numbers, though the type has attained an important position only in the Diesel marine and stationary engine field. Adhering to the principles that have been found indispensable to the successful development of marine Diesel two-stroke engines, some use­ ful results might be obtained. It is quite possible that an aircraft engine may be developed with a weight per horse-power not more, than one-half that of our present engines and with a thermal efficiency (referred to brake horse-power), especially at less than maximum power, better than has been secured with the four-stroke cycle engine up to date. The subject of charg­ ing, that is, supplying the fuel and mixing it with the required amount of air, affords great possibilities for development.

10 PROBLEMS IN AERONAUTICS By Dr. W. F. Durand, Scientific Attache, American Embassy, France; Lately Chairman the National Advisory Committee for Aeronautics.

Materials for Airplane Construction

For wing surface or covering, linen or cotton fabric is now in common or practically universal use. Sheet metal or metal fabric has received some attention. The chief advantage would be non-inflammability and perhaps greater durability. No wing covering can be considered which is markedly heavier than present forms for the same strength. Present coverings weigh from 4 to 4.5 ounces per square yard and have a tensile strength per inch of width of 70 to 80 pounds. Any proposed substitute form must also give a smooth and continuous surface comparable with present forms. For the wing skeleton or frame, spruce and wood veneer are commonly employed. Broadly speaking, the frame is of wood construction of one design or another. Steel or aluminum alloys are attracting attention and seem to offer possibilities. Any form of construction in metal must meet sensibly the present relation between strength and weight. This means that the wing must be capable of sustaining up to the point of rupturei a distributed load of not far from 100 pounds per square foot. No one should undertake the development of such construction without expert advice in applied mechanics, experience in steel construction, and with large shop and fabricating facilities available.

11 For fusilage construction the present materials are commonly spruce, ash, and wood veneer. Heavier woods, such as ash, can here be used to some extent. Steel or metal construction seems here also to offer hopeful possibilities, but under general limitations of equivalence regarding weight and strength compared with wood.

Ties and Fastenings The use of steel wire cable for ties is standard and practically universal. It seems hard to imagine material superior to the best modern alloy steel wire, but there seems no reason for assuming that such material represents the last word in the wire maker's art and there is, therefore, room for im­ provement even here, both in the material employed, in the mode of laying up wires to form a complex tie member and in the form of section of such member. Joint fastenings are commonly made of sheet steel or sheet bronze. There is room for improvement expressed in terms of ease of manufacture, economical distribution of material, facility for attachment of wire or cable ties, and general adaption to purpose.

Supercharging Engine The cylinder of the aeronautic engine takes in per cycle a cylinder full of air at substantially the atmospheric pressure about the carburetor. As the airplane ascends, the density of the air diminishes and there is, there­ fore, taken in per cycle a decreasing weight of air and hence a decreasing weight of oxygen. This reduces correspondingly the amount of fuel which can be burned per cycle and hence the power developed. It results that, as the airplane ascends to high altitudes meeting air of decreasing density, the power falls off accordingly, and very nearly in pro­ portion to the density. To meet this difficulty means are desired for supplying to the engine or to the carburetor air at a nearly constant air pressure. This implies some

12 form of air compressor taking in air at reduced pressure and density and delivering to the engine air at normal or nearly normal atmospheric pressure and density. This problem has already been solved or approximately solved so far as merely compressing the air is concerned. It is primarily a problem of finding the lest way of meeting the various limiting requirements regarding space, weight, reliability, etc.

Two Cycle Engine

If an engine operating on the two cycle program can be developed, with fuel economy and general reliability equal to that of the four cycle engine, the relation of weight to power should admit of substantial reduction. This is a favorite field for inventors and a large number of designs and sugges­ tions have been submitted. The field is still open.

Pitch Adjusting Propeller Closely connected with the maintenance of the power of the engine •at increasing altitudes is the problem of efficiently utilizing such power through the propeller. To this end some variation of pitch is desirable in order to maintain a proper relation between the torque of the engine and the resistance of the blade working in air of varying densities. Such varia­ tion of pitch is normally attended with loss in efficiency. Such loss should be reduced to Ahe minimum. The problem here is one partly of propeller design with reverence to aerodynamic qualities and partly one of structural design with reference to an operating and reliable form which will admit of adjustment of pitch to meet changing conditions of operation. Such change may be placed under hand control or under automatic or semi-automatic control between the limits imposed by the construction.

Spark Plugs

The general style of modern spark plug is the result of an evolution determined largely by the conditions of operation of the automobile engine. "With the higher compressions which are coming into vogue for the aeronau-

13 tic engine, increasing difficulties are met with in the spark plug, particularly as regards the breaking down of its electrical insulating qualities. A spark plug, apparently good in appearance, may last for many hours' hard service or it may give out after a few hours' running. The problem of ignition, especially for the aeronautic engine is one still awaiting satis­ factory treatment.

Parachutes These considered as a safety device are not desired as a factor in the equipment of military airplanes. No entirely satisfactory disengaging de­ vice has yet been developed. Such devices may presumably play some part in civil aeronautics and under peace conditions, but under existing military conditions they are not considered a necessary or desirable encumbrance.

Stabilizing Devices

The general subject of stabilizing devices is a favorite field for in­ ventors. Broadly speaking, there is small likelihood for the favorable con­ sideration of such devices under present war conditions. Aeronautic engi­ neers already know perfectly well how to give to an airplane any desired degree of stability in any one of the various senses in which the word is used. The problem is to combine judiciously the various modes of stability to­ gether with the qualities which are needful for military purposes. Without thorough training as an expert the average student of the subject is not likely to produce anything distinctly new or available in this particular field of aeronautic design.

Self-Starters

With increase in size and power of engines, the need of mechanical starters is becoming more and more clearly defined. The self-starter is a now recognized feature of seaplane equipment, and is attracting increasing in­ terest as a feature for land machines. Both electric and compressed air forms have been developed to a certain degree of efficiency. There is room for improvement as regards (1) size, (2) weight, (3) reliability.

14 Airplane Instruments Bomb sighting devices form a favorite field for the inventor. No one should enter this field without familiarity with the forms which the French and English have developed, and without a clear understanding of the conditions to be met. Target practice with bombs dropped from consid­ erable altitudes is decidedly poor and apparently is likely to remain so re­ gardless of the excellence of the sighting device as such. There is doubt­ less room for improvement in present forms, but the problem is not one which should be undertaken without a careful consideration of all factors entering into it. Speed indicating devices for showing speed through the air are in a fairly satisfactory condition. For the most part these instruments repre­ sent special forms of the Pitot tube and of the Venturi tube. These instru­ ments have been made the subject of a vast amount of scientific investiga­ tion and so far as existing forms are concerned, it does not seem likely that much improvement is to be expected. Speed indicating devices for showing speed over the ground. There is a distinct field of usefulness for a device suited to show continuously or at very brief intervals the speed of an airplane over the ground. Altitude indicating devices consist of some specialized form of aneroid barometer and are apparently in as satisfactory a condition as the delicate nature of these instruments permits us to expect. Drift meters for showing the angle between the fore and aft line of the airplane and the direction of actual motion, have been developed but there is room for improvement. True vertical indicating devices have been proposed in great numbers, but for the most part of the ordinary pendulum or spirit level type. All such are worthless. On the other hand, the methods of combining gyro­ scopic elements in such manner as to secure the desired result within an acceptable margin of error are perfectly well understood. It is not worth while attempting to develop such instruments by the use of the pendulum or spirit level principle.

15 AIRCRAFT PROBLEMS

By W. B. Stout, Technical Advisor Aircraft Board.

Aerodynamics The development of wing curves of greater lift-drift ratio; that is a greater lift with less resistance to forward travel. The development of wing curves of a high speed type which will have a small center of pressure movement through large angles of incidence. In making experiments to this end it will be necessary to use wind tunnels which give wind speeds exceeding one hundred miles per hour.

Performance A study should be made of new mechanical arrangements of known aerodynamic features, in order to increase the range of flying speed, to minimize landing danger, and to minimize fuel consumption through the elimination of all parasite resistance possible. A study should be made of new plane arrangements designed for greater visibility, for greater gun range, for quicker manceuvreing and for greater stability. The further possibilities of lightening the construction of airplanes and of making them more reliable should also be investigated. Anything which would tend to change the airplane from its present kite-type con­ struction to a more stable and long-life design would be in line with this thought.

Production The greatest problem connected with the airplane as related to America, is the development of production constructions which will permit airplanes to be turned out by methods already in use in this country for quantity •production. This problem would include intensive research upon the substitution of metal for wood wherever this is possible, also experiments with new steels and alloys and their heat treatment; which would enable ribs, spars, struts, ailerons, etc., to be made in thousands by machinery instead of in hundreds by handwork. Our eventual success in the air will depend upon

16 the ingenuity with which we can produce; first quantity of airplanes, and second, quality. The Germans lead today in the quantity production designs. In this connection a new covering for wings would be valuable, which would be fire proof, water proof, tough and resilient, and would take the place of the short-lived fabric now used. Fabric should weigh within four ounces per square yard and should have a tensile strength of 75 pounds with 1 inch width.

Propellers The airplane propeller presents a large field for research. Wooden propellers are far from satisfactory, though as yet no substitute has been found. Time should be spent in developing propellers which will permit motors to operate at the best speed (around 2,000 E. P. M.) without the necessity of gearing down from motor to propeller.

Instruments For airplane navigation better instruments could be developed. The compass is far from satisfactory, with the gyroscope compass not yet developed in light enough form. It is very possible that the future steer­ ing of airplanes will be along wireless rather than magnetic lines with definite control between cities.

Engine Problems Our engine program includes for war service, and very wisely, prac­ tically one type of engine. England alone is said to have some thirty- six types making the service proposition almost impossible. Germany has only three or four makes of engines, developing them to a greater degree of perfection every few weeks. Our own Liberty Engine is 50 per cent, better than it was six months ago and will be better still six months from now. If our development forces were being expended upon a hundred different engines instead of one, as would be the case if all or even our best engineers were allowed to work on aircraft engines promis­ cuously, no one of the engines would be fully developed in anywhere near the time that is possible by the present method. Practically no difficulty is being experienced with the engines them­ selves, and now there are but few relating to the airplane chassis and fusilage. The main problems are in the connection of the engine with the airplane, and in the accessories which are necessary for the proper

17 control of engine and plane. This includes the arrangement of pipe, wire, radiators, water connection, etc. New ideas for simplifying these parts are worthy of study. New arrangements of tanks to make the plane more bullet proof and to decrease fire danger should be studied. The recent developments in airplane motors all show that new things are about to be accomplished in the direction of high speed short distance work, and this field of research should not be neglected.

Types of Planes After the development of flying instruments reached a certain stage, night flying became popular. There is a demand already existent for planes of exceedingly large type capable of carrying tons of bombs and flying at night. This requires them to be stable. These machines should have from two engines up, and should be fitted with illuminating apparatus. Electric lights are not suitable but magnesium flares have been developed for this purpose. Night flying also involves new problems in protective measures relating to anti-aircraft guns, searchlights and combat tactics. Considerable speed can be added to all types of planes.

18 WORKING BIBLIOGRAPHY

For Aeroplane General Design and Aeromotors.

Laboratory Reports Giving Experimental Data ARTIFICIAL AND NATURAL FLIGHT. Hiram Maxim. N. Y., 1908, Macmillan Co. (Treats of Maxim's elementary experiments on wings and propellers, also of his full-scale experiments.)

BULLETIN DE L'INSTITUTE AERODYNAMINQUE DE KOUTCHINO, Riabouchinski. Bul­ letins No. 1-3, 1906-1909. Moscow, Russia, I. N. Kouchnereff & Cie, Pimen- ovskai'a 12.

DYNAMICAL STABILITY OF AEROPLANES, J. O. Hunsaker. Washington, 1916, Smith­ sonian Institution. (Mathematical and experimental treatise on balance,, oscillations damping, etc., of modern aeroplanes, with conclusions.) ESSAIS D'AÉRODYNAMIQUE, A. de Gramont, duc, de Guiche. Paris, 1911. Hatchette et Cie. (One of three publications of the de Guiche laboratory, representing wing tests made by mounting wings above a moving automobile.)

EXPERIENCES ET MESURES SURE L'AÉROPLANE EN PLEN VOL., J. Legrand. Paris, 1914, Librairie Aéronautique. (Account of experiments of various investiga­ tors. Reprint from records of Soc. Eng. Civils de France.) EXPERIMENTS IN AERODYNAMICS, S. P. Langley. Washington, 1902. Smithsonian Institution. (Second edition of report originally published in 1891 describ­ ing Langley's experiments with whirling table apparatus.)

L'INSTITUTE AEROTECHNIQUE A ST. CYK DE L'UNIVERSITÉ DE PARIS. All bulletins published to date. Paris, Dunod et Pinat.

NOUVELLES RECHERCHES SUR LA RESISTANCE DE L'AIR ET L'AVIATION. Faites an Laboratoire d'Anteuil. G. Eiffel. Paris, 1914 (2 vols.). Dunod et Pinat. (Treats of Eiffel's latest experiments in his enlarged wind tunnel at Anteuil. One of the most important available works on matters of aeroplane design.)

RECHERCHES EXPÉRIMENTALES SUR LA RESISTANCE DE L'AIB, EXÉCUTÉES A LA TOUR EDOTEL, G. Eiffel. Paris, 1907, L. Maretheux.

RENDICONTE DELLE ESPERIENZE E DEGLI STUDI ESEGUITI NELLO STABELEMENTB DE ESPERIENZE E CONSTRUZIONI AERONAUTICHI DEL GENIO. Published by Cav. V. Salviucci. Violi Giulius Caesare No. 2, Roma.

REPORT ON EUROPEAN AERONAUTICAL LABORATORIES, A. F. Zahm. Washington, 1914. Smithsonian Insti. (Brief description of leading European aerody­ namical laboratories.)

REPORTS ON TUNNEL EXPERIMENTS IN AERODYNAMICS, J. C. Hunsaker, et al. Wash­ ington, 1916. Smithsonian Insti. (Mathematical and experimental treatises on various features of aeroplane design.)

FIRST ANNUAL REPORT OP THE NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS, IT. S. Washington, 1916, Govt. Printing Office. (Containing reports from various sources especially prepared on such subjects as aeroplanes in gusts, wires, atmosphere, aircraft fabrics, aero engines.)

19 SECOND ANNUAL REPORT OF THE NATIONAL ADVISOBY COMMITTEE FOB AEBONAUTIOS, U. S. Washington, 1917, Govt. Printing Office. (Contributions from various sources bearing on the present status of aeronautics in the U. S.)

TECHNICAL KEPOBTS OF THE ADVISOBY COMMITTEE FOB AERONAUTICS. Great Britain. London, 1910 for 1909-10 report, 1911 for 1910-11 report, 1912 for 1911-12 re­ port, 1914 for 1912-13 report, Wyman & Sons. (These reports are the most valuable publications on aeronautics at present aavilable, giving results of a wide variety of laboratory tests on aircraft and aircraft parts, and applying these results to design use. Data is of the following general classifications : Air forces on models of airships, airplanes, wings, struts, bodies, wires, wheels, etc. Strength of materials, alloys ; characteristics of balloon fabrics ; stability moments, propellers, full scale experiments, wind tunnels.

RESISTANCE DE L'AIE, G. Eiffel. Paris, 1910, Dunod et Pinat. (Treats of various early laboratory experiments, including Eiffel's Champ de Mars Laboratory.

RESISTANCE OF A PLANE SURFACE IN A UNIFORM CUBBENT OF AIB, 1904—"Experi­ ments on Wind Pressures," 1907-8, T. E. Stanton. London. 1904 and 1908, Inst. Civil Engineers. (Early experiments made at the N«tional Physical Laboratory, Teddington, England.) THE RESISTANCE OF THE AIB AND AVIATION, G. Eiffel, N. Y., 1913, Houghton Mifflin Co. (Translation by J. C. Hunsaker of Eiffel's 1911 Report on wind tunnel tests. This and Eiffel's later report are the basis of French technical aerodynamics. Treats of the characteristics of wings, airplane models, pro­ pellers, etc.)

THEOBETISCHE UND EXPERIMENTEI.LE UNTEBSUCHUNGEN AN BALLONMODELLEN. George Fuhrmann. Berlin, 1912. Julius Springer.

UBER DIE STATISCHE LANGSTABILITAT DEE DBACHENFLUGZEUGE, ,Carl Wiesselberger. Berlin, 1913, Konigl Technische Hochschule zu Miinchen. (Wind tunnel ex­ periments.)

Theoretical and Technical Aerodynamics

ABBISZ DEE LEBBE VON DEB FLUSSIGKEIT UND GASTEUREGUNG, Prandtl.

AÉRODYNAMIQUE—BASES THEOREQUES DE L'AÉRONAUTIQUE, Jonkeuski. Paris, 1916, Gauthier-Villars.

DIE GESETZE DES WASSEK UND LUFT, O. Martienssen. Widerslauder, 1913.

A DISCUSSION CONCEBNING THE THEORY OF SUSTENTATION AND EXPENDITURE OF POWEB IN FLIGHT, F. W. Lanchester. Birmingham, 1915. Paper presented at International Engrg. Congress, Sept. 20-25, 1916, San Francisco. DYNAMICS OF MECHANICAL FLIGHT, Sir Geo. Greenhill. London, 1912, Constable & Co. (Lectures delivered 1910 and 1911 at the Imperial College of Science and Technology—Elementary theory of fluid dynamics.) FLIGHT WITHOUT FORMULAE, Duchene. London, 1914. Longmans Green. (Trans­ lation by Lederboer of a French text book of elementary airplane theory, published 1913 in France. ) HYDRODYNAMICS, A. S. Ramsey. (Theory of Fluid Dynamics.) MECHANICS OF THE AEEOPLANE, Capt. Duchêne. London, 1915, Longmans Green. (Translation by Lederboer & Hubbard of a French text book on airplane theory. )

20 SPEED AND POWER OF SHIPS, Taylor.

STABILITY AND EQUILIBRIUM OF FLOATING BODIES, B. C. Laws. N. T., 1914, D. Van Nostrand.

UBEB DIE LAGE DES AEBODYNAMISCHEN DEUCHMITTEL PUNKTES TISD EBENEN UND GEWOLHTEN FLACHEN, Inaugural Dissertation, R. Benitt Kiel, 1912, Ludke & Martens.

VEBSUCHE AN DOPPELDECKEBN ZUE BESTIMMUNG IHEEB EIGENGESCHWINDIGKEIT UND FLUGWINKEL, Wilhelm Hoff. Berlin, 1913. J Springer.

VOBLESUNGEN UBEB HYDEODYNAMIK UND GASDYNAMIK, L. Prandtl.

PBOPEETIES OF AEEOFOLLS AND AERODYNAMIC BODIES, by A. W. Judge, 1917. Pub. Wbittaker & Co.. London.

THE FLYING-MACHINE EBOM AN ENGINEEEING STANDPOINT. F. W. Lanchester, 1917. Pub. X>. VanNostrand & Co., 25 Park Place, N. Y.

THE RIGID DYNAMICS OF CIBCLING FLIGHT. G. H. Bryan. 1915. (In Aeronau­ tics, June 2 v. 7-8, pp. 371-72, 422-23, 440-42; vol. 9, pp. 42-44. Aerial Age Weekly. 1915. v. 2, pp. 60-61, 65, 85-86, 108-9, 134, 158.)

LONG TAILS VS. SBOBT TAILS IN AERODYNAMICS. G. H. Bryan and S. Brodtesky. 1916. (In Aeronautical Jour., 1916, April, vol. 20, pp. 50-55; Aerial Age Weekly, 1917, Mar. 19, vol. 5, p. 20.)

THE ELEMENTS OF AEEODYNAMICS AND THEORY OF FLIGHT. J. H. Ledeboer. 1915. (In Aeronautics, Aug. 4, vol. 9, pp. 76-78, 111-14, 147-8, 163-64, 183-4, 238-40, 296-7, 327-9. 392-4, 423-5.

COURSE IN AERODYNAMICS AND AIRPLANE DESIGNS.. Alexander Klemin and T. H. Huff, instructors in Aeronautics at Massachusetts Inst, of Technology, 1917. A series of articles during 1916 and 1917, beginning Aug. 1, 1916, to run for 24 issues in Aviation and Aeronautical Engineering and to be reproduced soon in book form. THE HELICOPTER FLYING MACHINE, J. Robertson Porter. 1911. Pub. by Aero­ nautics. 3 London Wall Bldgs., E. C, London.

Mathematical Treatment of the Theory of Aviation

AERODYNAMICS, CONSTITUTING THE FIRST VOLUME OF A COMPLETE WOBK ON AERIAL FLIGHT. F. W. Lanchester. London, 1907, A. Constable & Co.

AEEODONETICS, CONSTITUTING THE SECOND VOLUME OF A COMPLETE WORK ON AERIAL FLIGHT. F. W. Lanchester. London, 1910, (Second Ed.), Constable & Co. (These two large volumes form the basis of much of the later mathematical and analytical treatment of technical aerodynamics.) ETUDE DE LA STABILITÉ DE L'AÉROPLANE, Geo. de Bothezat. Paris, 1911. Dunod et Pinat. STABILITY IN AVIATION, G. H. Bryan. London. 1911, Macmillan & Co. (The author has succeeded in putting airplane stability on a mathematical basis.)

THÉORIE GÉNÉRALE DES REGIMES DE L'AEBOPLANE, Geo. de Bothezat. Paris, 1913, Dunod et Pinat. REPORT ON THE THEORY OF A STREAM LINE PAST A PLANE BARBIEE, and the dis­ continuity arising at the edge, with an application of the theory to an aero- plane. Sir G. Greenhill. London, 1910, H. M. Stationery Office. (Adv. Comm. for Aeronautics (Gt. Britain), Reports and Memoranda No. 19.)

21 Airplane Propellers AIRSCREWS, M. A. S. Riacli. London, 1916, Crosby, Lockwood & Son. (Excellent and clear treatise on working theory.) LUFTSCHRAUBEN-UNTFRSUCHUNGEN. F. Bendemann. Munich, 1912, R. Olden­ bourg. EXPERIMENTAL RESEARCH ON AIR PROPELLERS. Rep. No. 14, 1917. Advisory Com. for Aeronautics. Government Printing Office, Washington, D. C. EQUIVALENT MASS IN RIGID DYNAMICS, WITH APPLICATIONS TO GYROSCOPE AN» SCREW PROPELLERS, A. F. Zahm and W. P. Loo. J. Fr. Inst. 183: 207-10 F. '17. LES AVIONS ALLEMANDS, A. Masmejean Librairie, Aéronautique, 40 Rue de Seine 40, Paris. (Article on Machine-Gun Synchronizers.)

The Gyroscope

THEORY AND OPERATION OF THE GYROSCOPE, AND THE SPERRY GYROSCOPIC COMPASS» Ensign B. E. Gelling, U. S. N. (Reprint from XJ. S. Naval Proceedings. Vol. 38, No. 2. Whole No. 142. ENGINEERING APPLICATION OF THE GYROSCOPE, Elmer A. Sperry. (Reprint from Journal, Franklin Institute, May, 1913, J. B. Lippincott.) REPORT ON GYROSCOPIC THEORY, Sir Geo. Greenhill. London, 1914. H. M. Sta­ tionery Office. (Reports and Memoranda, Advisory Commission for Aero­ nautics. Great Britain.)

Designs of Airplanes AEROPLANE DESIGN, Lt. F. S. Barnwell. London, 1916, McBride, Nast & Co. (Elementary Lecture on General Layout and Balance of an Aeroplane. Bound with "Simple Explanation of Inherent Stability," by W. G. Sayers.) THE AEROPLANE, A. Fage. London, 1917, Third Ed., Chas. Griffin & Co. (Third Edition brought up to date Dec. 1916, contains as appendices : (1) A graphical method of calculating aerodynamical performance of an aeroplane; (2) a table of the results of some experiments on the skin friction of various sur­ faces; (3) miscellaneous design data. "The Aeroplane" is a concise intro­ duction to aeronautical engineering based on aeronautical data of the Na­ tional Physical Laboratory, treating of construction, stability, propeller» engine.) ARMY MILITARY AEROPLANE COMPETITION OF 1912. Report of Judge's Committee. London, 1912, T. F. TJnwin. DESIGN OF AEROPLANE, A. W. Judge. London, 1916, Whittaker & Co. (Collec­ tion of tables and diagrams taken from Technical Reports of the Advisory Committee for Aeronautics, and elsewhere.)

FLIEGERHANDBUCH, EIN LEITFADEN DEB GESAMTEN FLUGTECHNIK, R. Eyb. Berlin* 1914. R. C. Schmidt. (Excellent book for designer, containing clear dia­ grams and treatment of experimental aerodynamics, meteorology, construc­ tion, engines, propellers, with 70 pages on operation of controls in flight.)

HANDBUCH FUB FLTJGZETJG-KONSTBUKTETJRE ; EINE UBERSICHTLICHE ANLEITUNG ZTJB BERECHNUNG UND ZUM BAIT, Cammillo Hafïner. Berlin. 1913, R. C. Schmidt. (Useful for designers; treats of automatic stabilizers; contains construction diagrams. )

22 HILFSBUCH FUR DEN FLUGZEUGBAU, O. L. Skopik. Berlin, 1913. R. C. Schmidt. LEITFADEN DER FLUTECHNIK, Siegmund Huppert. Berlin, 1913. J. Springer. (Contains interesting treatment of stability, motors, propellers in theory and practice. Many construction diagrams.) MILITARY AEROPLANES, Grover O. Loening. Boston, 1916. W. S. Best Co. (Gen­ eral Principles of Design and Present Practice in TJ. S.)

PROPERTIES OP WING SECTIONS AND RESISTANCE OF BODIES. Whittaker's Specialist Series Vol. II. (Not yet published.) London, Whittaker & Co.

STRESS CONSIDERATIONS IN AEROPLANE DESIGN, A. F. Zahm. 1913.

WIE BERECHNET, KONSTRXJIERT UND BAUT MAN EIN FLUGZEUG? O. L. Skopik. Berlin, 1912, R. C. Schmidt. (Contains construction diagrams.)

WING DATA AND ANALYSIS FOR A STAGGERED BIPLANE, A. F. Zahm. J. B. Lippin- cott, 1914. (Method of determining strength of wings. Reprint, proc. Frank­ lin Institute.)

Seaplanes

LES HYDRO-AEROPLANES, F. R. Petit. Paris, 1912. Dunod et Pinat. (Theory and illustrations.) LES HYDRO-AEROPLANES, P. Riviere. Paris, 1913, Librairie Aéronautique. (Cba- tains illustrations ; no theoretical treatment. )

DIE WASSERDRACIIEN ; EIN BEITRAG ZITR BATTLICHEN EUTWICHLUNG DER FLUGMA- CHINE, Joseph Hofmann. Munchen, 1913, R. Oldenbourg. (Contains theory and illustrations ; treats of complications due to waves. )

Operation of Airplanes

THE AIRMAN, C. Mellor, 1913. (Experiences while obtaining a pilot's license in France.)

DER BLERIOT-FLUGAPPARAT UND SEINE BENUTZTJNG DURCH PEGOUD, P. Bejeuhr. Braunschweig, 1914, Frederich & Sohn.

ERECTING AND ALIGNING AN 80 H. P. AVRO BIPLANE TYPE 504. Manchester, 1915. A. V. Roe & Co., Ltd. ESSAYS OF AN AVIATOR. London, "Aeronautics," 170 Fleet Street. LE PILOTAGE D'UN AEROPLANE, P. Banet-Rivet. Paris, 1912, Gauthier-Villars. STABILITY OF AEROPLANES, Orville Wright. Washington, 1915, Smithsonian In­ stitution. (Reprint from Journal Franklin Inst., Sept., 1914.)

Military Uses of Aircraft

TRAINING MANUAL ROYAL FLYING CORPS (Provisional). Parts I and II. London, 1914, T. Fisher Unwin. (Part I. Care and operation of army aeroplanes. Part II. Military Organization of R. F. C. and methods of employing aero­ planes. )

AIRCRAFT IN WARFARE, THE DAWN OF THE FOURTH ARM, F. W. Lanchester. Lon­ don, 1916, Constable & Company.

23 Bird Flight AEROPLANE DESIGNING FOE AMATEURS, Victor Lougheed. Chicago, 1912, Reilly Britton Co. (Experiments to determine Bird Wing Shapes, page 56.)

ANIMAL FLIGHT, Hankin. London, 1913, Iliffie & Sons. (Observations in India and Egypt.)

ANIMAL LOCOMOTION, WALKING, SWIMMING AND FLYING, J. B. Pettigrew. New York, 1874, D. Appleton & Co.

ANIMAL MECHANISM—A TREATISE ON TERRESTRIAL AND AERIAL LOCOMOTION, E. J. Marey, New York, 1874, D. Appleton & Co. (Laboratory Analysis of Bird Wing Stroke; International Scientific Series Vol. II.)

AVIATION, COMMENT L'OISEAU VOLE, COMMENT L'HOMME VOLERA, Wm. Kress. (1905, Translated into French from German 1909.)

BIRD FLIGHT, AS THE BASIS OF AVIATION, Otto Lillienthal. Berlin, 1889. English translation, N. Y., 1911. Longmans, Green & Co. (Results of numerous ex­ periments made by O. and G. Lillienthal.)

COMMENT VOLENT LES OISEAUX—LE VOL RAME, R. Desmons. Paris, 1910, Dunod et Pinat.

DIE FLUGBERWEGUNG DER VOSEL, Karl Milla. Leipsig, Vienna, 1895, F. Deuticke.

L'EMPIRE DE L'AIR, L. P. Mouillard.- Paris, 1881, G. Masson. (Pioneer study of soaring birds and gliders. An English translation, "The Empire of the Air," was published 1893 by U. S. Govt. Printing Office.)

ESSAY ON THE THEORY OF THE FLIGHT OF BIRDS, BATS, AND INSECTS, O. J. L. Krarup-Hansen. Copenhagen, 1869, O. Steen & Fils. (Popular treatise.) FLIGHT OF BIRDS, G. A. Borelli, London, 1911. Aeronautical Soc. of Great Britain» (Republication of Borelli's work as one of the "Aeronautical Classics.") FLIGHT OF BIRDS, F. W. Headley. London, 1912.

FIRST REPORT OF THE BIRD CONSTRUCTION COMMITTEE, J. D. Fullerton, London. THE GREATEST FLYING CREATURE, S. P. Langley and E. A. Lucas. Washington. Published by the Smithsonian Institution.

LES ORGANES DE LOCOMOTION AÉRIENNE CHEZ LES VERTÈBRES VOLANTS, R. Anthony.. Paris, 1913, Librairie Aéronautique.

PHYSIOLOGIE DU MOUVEMENT, LE VOIL DES OISEAUX, E. J. Marey, Paris, 1890, G. Masson. LA RESISTANCE DE L'AIR ET LE VOL DES OISEAUX, Maurice Gaudillot. Paris, 1911» Gauthier- Villars.

RECHERCHES SUR LE VOL DES OISEAUX ET L'ART AÉRONAUTIQUE, M. J. A. Dubocket, Nantes, 1834, Imprimerie de Mellinet.

SAILING FLIGHT, FROM OBSERVATIONS MADE AT CONSTANTINE, ALGERIA, J. Breton- niere. 1894. (Copy in John Crerar Library, Chicago.) VOGELFLUG, Wilhelm Winter. Miinchen, 1895, Theodor Ackermann. LE VOL SANS BOTTEMENT, L. P. Mouillard. Paris, 1912, Librairie Aéronautique (Posthumous unpublished work.)

24 General and Historical Books of an Elementary Nature AEEIAL NAVIGATION, A. F. Zahm. New York, 1911, D. Appleton & Co., (A popular and entertaining treatise on tlie development of mechanical flight.) AEBO MANUEL: Repertoire sportif, technique, et commercial de l'Aéronautique, Faroux & Bonnet. Paris, 1914, Dunod et Pinat. (Comprehensive volume treating of the history, sports, technical and commercial side of aeronautics ; with many illustrations, tables and technical notes, the latter chiefly taken from Eiffel.) AERONAUTICAL ANNUAL, James Means. Boston, 1895, 1896, 1897, W. B. Clarke & Co. (Three volumes containing articles by authorities of the time, and representing the state of the art at that time. Excerpts published in 1910 in a fourth volume, "The Epitome of the Aeronautical Annual.") AERONAUTICAL CLASSIC. London, Aeronautical Society of Great Britain. (Com­ prises historical treatises as follows : "Aerial Navigation," Sir Geo. Cayley ; "Aerial Locomotion," Wenham ; "Art of Flying," T. Walker ; "Aerial Ships," Lana ; "Gliding," Percy Pilcher and Stringfellow ; "Flight of Birds," Borelli.

L'AÉRONAUTIQUE NAVALE MILITAIRE MODERNE, FRANCE ET L'ETRANGER, Ch. Lafon. Paris, 1914, Dunod et Pinat. AVIATION, A. E. Berriman. London, 1913. Methuen & Co. (Second Edition.) (An introduction to the elements of flight.) AVIATOR'S COMPANION, Dick and Henry Farman. London, 1910, Mills & 'Boon. (Interesting personal experiences of the authors.) AIRSHIPS PAST AND PRESENT, A Hildebrandt (Capt. in Prussian Balloon Corps). London, 1908 (Trans, from the German by W. H. Story), Archibald Conr stable & Co. (Treats of balloons and dirigibles in a popular way.) AIRCRAFT IN THE GREAT WAR, Claude Graham and Harry Harper. London, 1915, T. F. Un win. (Popular description of military uses of aircraft.)

ALL THE WORLD'S AIRCRAFT, WAR FLYING ANNUAL, F. T. Jane. London, 1916, Sampson Low, Marston & Co. (Illustration and dimensions of aircraft of different nations.) CURTISS AVIATION BOOK, Glenn H. Curtiss and Augustus Post. N. X., 1912, F. A. Stokes. (Biography and early experiences with Curtiss machines.)

FIRST MAN-CARRYING AEROPLANE CAPABLE OF SUSTAINED FREE FLIGHT—LANGLEY'S SUCCESS AS A PIONEER IN AVIATION, A. F. Zahm. Washington, 1915, Smith­ sonian Institution. (Account of flights of reconstructed Langley "Aero­ drome." ) FLYING ; SOME PRACTICAL EXPERIENCES, Gustave Hamel and C C. Turner. London, 1914, Longmans Green & Co. (Popular treatise with photographs, many of them taken from flying machines. ) JAHRBUCH DER LUFTFAHRT, A Vorreiter. Munchen, 1912 (Annual publication, J. F. Lehmann.) (An excellent general book.)

JAHRBUCH DER WISSENSCHAFTLICHEN GESELLSCHAFT FUR FUGTECHNIK. Berlin, 1913, 1914, 1915, J. Springer. MEMOIR ON MECHANICAL FLIGHT, S. P. Langley and C. M. Manely. Washington, 1911, Smithsonian Institution. (Construction and experiments with model and full sized self-propelled flying machines; sequel now being compiled.) Mr AIRSHIPS, Santos Dumont. N. Y., 1904, Century Co. (Popular accounts of early experiments with dirigibles.)

25 PROGRESS IN FLYING MACHINES, Octave Chanute. N. Y., 1894, American Engr. & R. R. Journal. (Compendium of experiments to date, 1894, made through­ out the world in mechanical flight.) REVUE GÉNÉRALE DE L'AÉRONAUTIQUE. Paris, Libraire Aéronautique. (Vols. 1-4 published several years ago, each volume by a different author.) ROMANCE OF AERONAUTICS, C. C. Turner. London, 1912, Seeley Service & Co. (An interesting account of the growth and achievements of all kind of air craft up to 1912.)

RESEARCHES AND EXPERIMENTS IN AERIAL NAVIGATION, S'. P. Langley. Washing­ ton, 1908, Smithsonian Institution. (Accounts of successful experiments with the Langley model airplanes.)

TASCHENBUCH DER LUFTFLOTTEN (KRTEGSAUSGABE), F. Rasch and W. Hormel. Munich, 1915, J. F. Lehmann. (Pictures of balloons, dirigibles, airplanes and engines.) LA TECHNIQUE AÉRONAUTIQUE, Tomes 1-6. Paris, 1912, Librairie Aéronautique. (These volumes were published twice a year ; containing technical and gen­ eral treatises. Nos. 5 and 6 bear date 1912.)

Books Introductory to the Art

ACQUIRING WINGS, W. B. Stout, Chief Engineer Packard Motor Co. Pub. by Moffat, Yard & Co., 120 West 32nd St., N. Y. 1917. ELEMENTARY AERONAUTICS, A. P. Thurston, London. Pub. Whittaker & Co. 1911. How TO UNDERSTAND AEROPLANES, S. L. Walkden. Pub. Percival Marshall & Co., 66 Farringdon St., London, 1914. LEARNING TO FLY, E. N. Fales. Pub. McGraw-Hill Book Co., 239 W. 39th St., N. Y. 1917.

AEROPLANE DESIGN AND INHERENT STABILITY, F. S. Barnwell & W. H. Sayers. Pub. McBride, Nast & Co., London. 1916. PRACTICAL AERONAUTICS, Chas. B. Hayward. 1918. Pub. Am. Tech. Soc, Chicago. (A collection of papers of the Am. School of Correspondence.) FLIGHT WITHOUT FORMULAE, Commandant Duchene Trans, by J. H. Ledeboer. Longmans, Green & Co., 39 Paternoster Row, London, 1914. (Listed also under "Theoretical Aerodynamics" and Designers' "Condensed List.") THE AVIATION POCKETBOOK, R. B. Matthews. Pub. Crosby, Lockwood & Son, Lon­ don. 1917. MECHANICAL ENGINEERS' HAND-BOOK, L. S. Marks. Chapter upon Aeronautics by Dr. J. C. Hunsaker. Pub. McGraw-Hill Book Co. 239 W. 39th St., N. Y.

Condensed List. For Designers' Use, of Works Previously Mentioned

AERODYNAMICS, Lanchester. AERODONETICS, Lanchester, AEROPLANE, 3rd Ed., Fage. AIR SCREWS, Riach. FLIEGERHANDBUCH, Eyb. FLIGHT WITHOUT FORMULAE, Duchene. HYDRODYNAMICS, Lamb. MECHANICS OF THE AEROPLANE, Duchene.

26 MILITARY AEROPLANES, Loening. MECHANICAL ENGINEER'S HANDBOOK, Marks. NOUVELLES RECHERCHES SUR LA RESISTANCE DE L'AIE ET AVIATION, Eiffel. RESISTANCE OF THE AIR AND AVIATION, Eiffel-Hunsaker. FOUR TECHNICAL REPORTS OF THE ADVISORY COMMITTEE FOR AERONAUTICS, Great Britain, with other reports as they appear. Two REPORTS OF THE ADVISORY COMMITTEE FOR AERONAUTICS, United States, with other reports as they appear. STABILITY IN AVIATION, Bryan. STRESS CONSIDERATIONS IN AEROPLANE DESIGN, Zahm. WING DATA AND ANALYSIS FOR STAGGERED BIPLANE, Zahm. ROYAL TRAINING CORPS FLYING MANUAL, Great Britain.

Bibliography of Aeronautical Patents

ABRIDGMENT OF AERONAUTICAL SPECIFICATIONS FILED AT THE BRITISH PATENT OFFICE, 1815-3891, Brewer & Alexander. London, 1893, Taylor & Francis.

AEROPLANE PATENTS, R. M. Neilson. London, 1910, Constable & Co. (U. S. and British Patents.)

DIE DEUTCHEN PATENTE UBER FLUG-APPARATE 1879-1911, Alexander-Katz. Berlin, 1912, M. Krayn.

REPERTOIRE DESCRIPTIF DES BREVETS D'INVENTION DETURES EN FRANCE. Paris, 1910, Librairie Aéronautique. (1910 Volume continued from Vol. I.) See also U. S. and British Patent Office Reports.

Bibliographies

BIBLIOGRAPHY OF AERONAUTICS, Paul Brockett. Washington, 1910, Smithsonian Institution. (This comprehensive volume is now being brought up to date.)

SUBJECT LIST OF WORKS ON AERIAL NAVIGATION AND METEOROLOGY IN THE LIBRARY OF THE BRITISH PATENT OFFICE. London, 1905, British Patent Office Library, Series No. 17.

LIST OF WORKS ON AERONAUTICS IN THE SCIENCE LIBRARY OF THE SOUTH KENSING­ TON MUSEUM TO NOV. 12, 1913. London, 1913, H. M. Stationery Office.

BOOKS ON AERONAUTICS IN THE ST. LOUIS, MO., PUBLIC LIBRARY. C. C. Crailie, St. Louis, Mo., Public Library.

CARD CATALOGUE OF AERONAUTICAL WORKS IN THE JOHN CRERAB LIBRARY, CHICAGO. (Comprehensive collection, including private library of Octave Chanute.)

LIST OF BOOKS AND REFERENCES OF PERIODICALS IN THE BROOKLYN PUBLIC LIBBABY. Brooklyn, 1909, Brooklyn Public Library.

ORGANIZATION DE LA BIBLIOGRAPHIE GÉNÉRALE DE L'AÉRONAUTIQUE. H. Hervé. Paris, 1900, Violet.

27 MOTIVE POWER FOR AEROPLANES ENGINEERING THEBMODYNAMIOS, Charles E. Lucke, Columbia University, 1912. Pub. McGraw-Hill Book Co., 239 West 39th St., New York. Very complete. This work is abridged as the Text-book of Engineering Thermodynamics by C. E. Lucke and J. J. Flather, 1915. Same Pub. TECHNICAL THERMODYNAMICS, Gustav Zeuner, Trans, by J. F. Klein, 1908. Vol. I. Theory of Gases. Vol. II. Theory of Vapors. Pub. D. Van Nostrand Co., 25 Park Place, New York. THE THEORY OF HEAT ENGINES, William Inchley, 1913. Pub. Longmans-Green & Co., 39 Paternoster Row, London. THE GAS TURBINE, Norman Davey, 1914. Pub. Constable & Co., Ltd., 10 Orange Street, Leicester Square, W. C. London. THE GAS TURBINE, Henry Harrison Suplee, 1910. Pub. J. B. Lippincott Co., Phila­ delphia, Pa. THE GAS TURBINE, Hans Holzworth, 1912. Trans, by A. P. Chalkley. Pub. J. B. Lippincott Co., Philadelphia, Pa. THE STEAM TURBINE. By A. Stodola. Trans, by L. C. Loewenstein. Pub. D. Van Nostrand Co., New York, 1905. THE FLOW OF STEAM THROUGH NOZZLES. By A. Rateau. Trans, by H. B. Brydon. Pub. D. Van Nostrand Co., New York, 1905. HIGH SPEED INTERNAL COMBUSTION ENGINES, A. W. Judge, 1916. Pub. Whittaker & Co., London. THE GAS PETROLEUM AND On, ENGINE. Two Vols. Vol. I. Thermodynamics of the G. P. & O. Engine, D. Clerk, 1909. Pub. John Wiley & Sons, 432 4th Avenue, New York. Vol. II. The G. P. & O. Engine in Practice, D. Clerk and G. A. Burls, 1913. Pub. Longmans, Green & Co., 39 Paternoster Row, London. EVOLUTION OP THE INTERNAL COMBUSTION ENGINE, Edward Butler, 1912. Pub. J. B. Lippincott Co., Philadelphia, Pa. THE GASOLINE MOTOR, P. M. Heldt, 1916. Pub. P. M. Heldt, Nyack, N. Y. AUTOMOBILE AND GASOLINE ENGINE ENCYCLOPAEDIA, A. L. Dyke, 1917. Pub. A. L. Dyke, St. Louis, Mo. GAS AND OIL ENGINES, Marks and McDowell. Chicago, 1916. American School of Correspondence. (Vol. I contains theory of explosion motors and an excellent treatise on carburetors. Vol. II treats of gas engines and high speed automobile engines. Vol. Ill treats of ignition, timing operation.) CARBURETORS, VAPORIZERS AND VALVES, Edward Butler, 1909. Pub. J. B. Lippin­ cott Co., Philadelphia, Pa. THE VAPORIZING OF PARAFFIN FOR HIGH SPEED MOTORS, Edward Butler, 1917. Pub. J. B. Lippincott Co., Philadelphia, Pa. CARBURETION IN THEORY AND PRACTICE, Robt. A. Brewer, 1913. Pub. Crosby, Lockwood & Son, 7 Stationer's Court, E. C. London. CARBURETOR DESIGN, Lucke & Wilhofft, 1917. In Second Annual Rep. Nat. Ad­ visory Com. for Aeronautics. AVashington. Government Printing Office. ELECTRIC IGNITION, F. R. Jones, 1912. Pub. Wiley & Sons, N. Y. AERO ENGINES, G. Burls, 1915. C. Griffin & Co., London. (With introductory account of the Theory of the Internal Combustion Engine.) MOTEUR GNOME, Audree Preynat. Paris, 1913. Dunod et Pinat.

28 MOTORS FOB AERONAUTICAL PURPOSES, Alexander Prize Motor Competition. Lon­ don, 1911. H. M. Stationery Office. MOTOEEN FUR FLITGZEUGE TJND LUFTSCHLFFE, Fritz Huth. Berlin, 1914. R. C. Schmidt. (Treats of the fundamental practical considerations in aero engine design, with diagrams and many photographs. A good book, but old.) REPORTS OF THE COMPETITION FOR THE GERMAN CHANCELLOR'S $20,000 "AERO ENGINE PRIZE." 1912. (Published in "Zeitschrift des Vereines Deutchen Ingenieure," Jan. to June, 1913, pp. 481, 692, 801. See also pp. 372, 583. These articles are considered an authority in America and have been pub­ lished in the Aerial Age Weekly, March 19, April 2, June 11, 1917, under the title "German Aeroplane Engine Trials." PERIODICALS DEALING WITH AEROPLANES AND AEROMOTORS The current technical literature is now so large and is being produced at such a rate that no attempt to list it or even to select from it would be useful here. Every investigator will consult the well-known indexes avail­ able at all libraries and will familiarize himself with the Journals and Technical Societies' publications, which deal with aeronautics. Most of the strictly technical articles and information will be found in the following partial list :

Journals Aerial Age Weekly, 280 Madison Ave., N. Y. Aviation and Aeronautical Engineering, 120 West 32nd St., N. Y. Semi­ monthly. Aircraft, Plainfleld, N. J. Monthly. Aeronautics, 6 Bouverie St., London, E. C. 4. Weekly. Aeronautical Journal, 7 Albemarle St., Adelphi, London, W. i. Monthly. The Aeroplane, 166 Piccadilly, London. Weekly. Flight, 36 Great Queen St., Kingsway, W. C. 2, London. Weekly. L'Aerophile, 35 Rue Francois 1er. Monthly. La Guerre Aérienne, 30 Rue de Provence, Paris. Weekly. Automotive Industries. (Until recently the Automobile), 239 W. 39th St., N. Y. Weekly. Motor Boating, 119 West 40th St., N. Y. The Scientific American and the Scientific American Supplement, 233 Broad­ way, N. Y. Weeklies. The Automobile Engineer, 20 Tudor St., London E. C. Monthly.

Technical Society Publications Journal Society of Automotive Engineers (formerly the S. A. E. bulletin), 29 West 39th St., New York. Journal American Soc. Mechanical Engineers, 29 West 39th St., N. Y. Journal Franklin Institute, Philadelphia, Pa. Monthly. Proceedings Institution of Automobile Engineers. London.

* Footnote—The above bibliography includes by permission portions of one published by Aviation and Aeronautical Engineering, 120 W. 32nd St., N. Y., May 1, 1917, entitled "Two Hundred Books on Aeronautics," by E. N. Fales.

29 WAR COMMITTEE OF TECHNICAL SOCIETIES AND ITS WORK

The work which the War Committee of Technical Societies has under­ taken is to distribute war problems to the scientific and technical men of the country at their own homes, and to bring into action upon these problems the inventive ability of the country which is now partially latent.

By stimulating these trained men, together with the wider circle to be also reached through them and by the aid of the Technical Journals, it is hoped to concentrate the attention of American inventors upon the matters which are important, in which they can be most effective, and to aid them in the rapid development of their work. The problems, selected from every available source, will be prepared with the aid of specialists and issued to the membership (about 50,000) of the Societies already represented, accompanied by such a presentation of the Present State of the Art as will best interest and stimulate inventive ability. As rapidly as effective arrangements can be made it is expected to reach the membership of all Technical Societies, and also the general inventive ability of the country. Certain kinds of war problems, such as those requiring secrecy and re­ lating to the development and perfecting of certain devices, can only be submitted to a limited number of specialists. Most problems, however, are suitable for general presentation to that vast reserve capacity of knowledge and inventive ability which cannot be identified and selected. The work of the Committee, aided by the prominent specialists, is to bring this unknown capacity into action and to secure quickly the most promising contributions to the cause. The necessary trials and experiments will be conducted upon ideas and inventions which are of value. All inventions which have successfully passed the necessary examinations and tests are turned over to the particular depart­ ment of the Army and Navy Service, where they may be most profitably utilized.

30 Inventions and suggestions received by the Naval Consulting Board are examined in a preliminary way by the Secretary, who is aided by the following com­ mittee of examiners :

CHARLES MESSICK—Lieutenant (j. g.), U. S. N. R. F., detailed to Sec­ retary's office Naval Consulting Board; Member Am. Inst. Elec. Engrs.; Patent Attorney; developed and patented electrical hoisting and conveying machinery; developed and patented new methods in continuous casting of soft metal; developed and patented the combined clutch and adjustments device used on modern motorcycles, etc., etc.

G. HERBERT CONDICT—Consulting Engineer; Member Am. Inst. Elect. Engrs.; Franklin Inst.; Member Executive Committee, American Peat Society; Past Près. N. Y. Electrical Society. Among other activities, 1896-7, Genl. Mgr. and Chief Engr. Englewood-Chicago Electric Ry.; 1897-1903, Chief and Consulting Engineer, Electric Vehicle Co., New York and Hartford; 1903-06, Vice-Pres. and Genl. Mgr. Electro-Dynamic Co. in New York; 1906-09, Genl. Mgr. Box Electric Drill Co.

CARL K. MAC FADDEN—Technical advisor of companies interested in petro­ leum; Member Society Naval Architects and Marine Engineers; Associate Member American Soc. Naval Engineers; Fuel Oil Expert and Consulting Engineer.

CHARLES E. PARSONS—Consulting Engineer; B. E., Union College, 1898; 2nd Lieut. Second New York Volunteer Infantry, Spanish-American War; Chief Engineer Hudson River Water Power Co. and Atlanta Power Co., 1898 to 1913; President Ambursen Construction Co. to 191.5; Vice-President Deppe Motors Corporation; Member American Society Civil Engineers; Associate Member American Institute Electrical Engineers.

SAMUEL E. DARBY—Patent Lawyer and Expert; attended United States Naval Academy, 1882-86; Assistant Examiner and Chief Clerk U. S. Patent Office, 1886-94; Commander, 1901-03, and Captain commanding Illinois Naval Reserve, 1903-05.

DONALD M. BLISS—Consulting Engineer; Chief Engineer, Holtzer-Cabot Electric Co., Designer of electric motors and special devices for battleships, navy yard and coast defense apparatus, direct and alternating current motors, 1896-1907; President, Engineering Specialty Co., 1908-09; Chief Engineer, Laboratories Thomas A. Edison, 1910-13; designed and equipped Munition Plant of Canadian Car & Foundry Co., 1914-15; Proprietor, D. M. Bliss Co., New York.

GUSTAVO L. GOVIN.

GEORGE H. KIRSCH. ALAN T. BURLEIGH, Office Manager.

31 NAVAL CONSULTING BOARD of the United States. Addicks, Lawrence Miller, Spencer Arnold, Bion J., Lieut. Col. Richards, Prof. Jos. W. Baekeland, Dr. L. H. Riker, Andrew L. Brunton, D. W. Robins, Thomas Coffin, Howard E. Saunders, W. L. Craven, Alfred Sellers, Matthew Bacon Edison, Thomas A. Sperry, Elmer A. Emmet, William Le Roy Sprague, Frank J. Hunt, Andrew Murray Thayer, Benjamin B. Hutchison, Dr. M. R. Webster, Dr. A. Gordon Lamme, B. G. Whitney, Dr. W. R. Maxim, Hudson Woodward, Dr. Robert S. President Vice-Chairman Thomas A. Edison Benjamin B. Thayer Chairman •Secretary W. L. Saunders Thomas Robins War Committee of Technical Societies.

Harold W. Buck American Institute of Electrical Dr. A. S, McAllister Engineers Nelson P. Lewis American Society of Civil Major James M. Boyle Engineers Prof. A. M. Greene, Jr. American Society of Mechanical R. N. Inglis Engineers David W. Brunton American Institute of Mining Edmund B. Kirby Engineers Dana D. Barnum American Gas Association E. C. Uhlig Joseph Bijur American Electro Chemical Dr. Charles A. Doremus Society Louis B. Marks Illuminating Engineering Preston S. Millar Society Christopher R. Corning Mining and Metallurgical George C. Stone Society of America Dr. Charles F. McKenna American Institute of Chemical Frank E. Dodge Engineers Henry Torrance American Society of Refrigerating F. E. Matthews Engineers

Dr. John Johnston American Chemical Society Dr. Charles Baskerville (Co-operating) W. D. Richardson hairman Acting Secretary / D. W. Brunton Edmund B. Kirby