FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1917
1917 - 0684.PDF
1/llGHT] Much of the laboratory instruction undertaken at the technical college will thus necessarily be of the nature of research, although a good grounding will have to be given in the more usual work dealing with the testing of the strength and properties of material and with the testing of engines generally. In the testing of materials now commonly used in aero- plane construction, pew materials will from time to time have to be tried. In addition to the testing of cables, strainers, and struts and ties, experiments will have to be made on simple and complicated steel and other plate and bolt attachments for building up the light skeleton aeroplane fuselage of Wood and metal. The materials-testing laboratory for aeronautical engineering students will thus become, at any rate for some years, primarily a research laboratory. Taking timber, for example, as used in aeroplane building, it might be thought that sufficient experimental data had been accumulated regarding spruce and other woods. But this is not the case, though probably there is much more data available than has been published. Much of the requisite experimental work remains yet to be done in the determina- tion, inter alia, of the effect, on the strength and elasticity of the material, of defects inherent in the natural growth of the timber. It has been shown, for instance, that the useful strength of timber is due to that part of its morphological structure known as " mechanical tissue," and experiments have been made which seem to point to the conclusion that this tissue is actually stronger than steel, but, of course, it is diffused or spread out by other vegetable or cell structures of negligible strength. Here alone is a vast field for research. Can this mechanical tissue be concentrated into close bundles giving relatively enormous strength, and if so, will the density of the material be then so high as to prohibit its use ? Obviously the density, or mass per unit volume, is a factor which cannot be neglected in aeroplane Work. Some woods are too heavy to be used at present. One of the author's assistants in a research carried out in the Materials Laboratory at the Northampton Polytechnic Institute, showed, for example, that the compressive strength of different kinds of timber was a linear function of the density—a very important result. Other properties, such as tenacity, deflection, and, in the case of struts, buckling, may also be a function of or dependent on the density. Then investigations are required on the strength and elasticity of timber, for the effects of knots and gum veins, the straightness or otherwise of the grain, the closeness of the mechanical tissues, the direction of the grain with respect to the plane of flexure. The effects of water absorbed during variable conditions of climate, e.g., snow, rain or clouds, and the hygrometric state of the air on the material of the timber, have yet to be investigated. There is further the necessity of testing plate and other attachments, by means of which the timber parts are secured together to form the skeleton structure of the fuselage, and in this connection those who have had to deal With the design and testing of these plate attachments for wood members know how very difficult it is to secure so firm a holding on such a light wood as spruce as to stand a reason- able working stress. Here again is a valuable field for laboratory work. Turning to another matter, a very prominent part of the laboratory equipment must consist of a Wind tunnel, with its motor-driven propeller and provided with indicating and recording instruments for experiments and research on models -of planes and wing surfaces or structures, on models or parts of aeroplane structures, &c. Part of the wind tunnel should be arranged so that the air or stream line flowing past a plane model or solid obstacle can be made visible and the resistance measured. That is, the experimental work should be qualitative as-Well as quantitative in the deter- mination of lift and drift for surfaces of varying forms and aspect ratios, and the resistance of models of aeroplane parts which are required to cut through the air. Indications of best sections • and forms can in this way be obtained and provisional designs satisfactorily adjusted. Workshop and practical work.—In the genetal scheme the bulk of the workshop and practical work is to be taken in actual and not in the college workshops during the two summer periods, and if in particular cases additional work of this kind is deemed to be necessary, it would naturally fall to be"taken at the end of the fourth session. In aeronautical engineering there is one kind of practical work, namely, aviation or flying, which cannot under present conditions be included in the course at a technical college, but in regard to which the student should acquire some definite knowledge. While, therefore, the educational course cannot deal with flying qua flying, yet it will be of advantage JULY 5, 1917. to arrange for perioiUcal visits of the students to the flying grounds and even to provide for some lectures given by an engineer-aviator on the behaviour of aeroplanes under prac- tical conditions of flight. I* addition, as in other branches of engineering education, visits should be paid to works in which aeroplanes are in various stages of construction.. In this way the student will be stimulated in his studies and will gain some insight into the every-day work of the aeronautical engineer. It may even be found to be possible in the case of th£ senior students to arrange for trial flights so as to familiarise them still further with the behaviour of the machines upon the theory and designing of which so much of their time will have been spent. The case is analogous to that of the student apprentices of locomotive engineering or of marine engineering, Who are always ambitious to take part in a trial run or a trial trip. Similarly, it is natural to suppose that a trial flight (not as pilot) will have attractions as well as being practically valu- able for the student apprentice who is approaching the end of his college training in aeronautics. Perhaps even the day is not far distant when the require- ments of education and research will justify an experimental aerodrome, laboratory and flying ground for experiments on a larger scale and of much wider applications than is possible at the present time. The chief obstacle at the present time is the necessarily heavy expenditure. Special and Evening Instruction. No scheme for the education of aeronautical engineers can be considered complete at the present time which fails to take into account the general as well as the specialised instruction required by the very large number of engineers and engineering students who for various reasons are quite unable to attend aeronautical courses in an engineering day, college. These men may for the most part be placed in one or other of the following classes or categories :— 1. The rank and file of apprentices, learners, improvers and journeymen, the best of whom may subsequently rise to class 2, and who are employed or employable in the shops an<J drawing-offices. 2. Trained engineers, civil, mechanical, electrical, or military, who have already received in varying degrees of proficiency the educational training qualifying them for the particular branch of engineering in which they are or have been employed and who from the force of circumstances have changed over or intend changing over to aeronautical engineering. From the necessities of the case it goes without saying that, up to the present, the best design and con-- structive work in aeronautics has been done by men Who received their technical education in one or other of the older branches of engineering before aeronautical * work developed and this training has proved invaluable to them as a solid foundation for the specialised Work of aeronautics. For some time to come the ranks of the aeronautical engineer will still be recruited from men already possessing those solid qualifications, the more ambitious of whom will be eager to supplement their training and experience by special s/udy of the new science. / For the first-named or apprentice category an excellent start, well calculated to arouse the interest and stimulate the ambition of many who are only too much inclined to waste their leisure time, has been made in the series of works lectures which have been inaugurated by the society during the present session, and which it is proposed to extend in the coming autumn and winter. Further reference is made to this work later. ' It is not likely, however, to be overlooked that if sub- stantial educational benefit is to follow from these lectures, regular and systematic courses must be attended in a well- organised technical college. Such students will have to face much preliminary work in mathematics and general engineer- ing theory, in drawing office and laboratory work before any real progress can be made by attendance at classes dealing specially with aeronautical engineering. Indeed, it will be found in this connection as with other branches of engineering that a very large number, probably the majority, will never effectively_get beyond the mere elements of workshop calcu- lations and drawing. Many are called but few chosen. Aeronautical engineering, like other professions, requires its " heWers of wood and drawers of water." Notwithstanding, it is advisable to arrange lecture courses and practical work of an elementary character in aeronautics specially suitable to the requirements of the man %vho will join the artisan section of this important industry. He will be a far better workman because of a knowledge of workshop arithmetic and drawing, supplemented by simple laboratory experiments 684
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
