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Aviation History
1913
1913 - 0157.PDF
FEBRUARY 8, 1913. 45. To one special point the Committee desire to call attention. It is, unfortunately, a somewhat common practice for flyers to descend intentionally in a vol pujui. Owing to the serious nature of the stresses induced, the Committee are of opinion that this involves an unnecessary risk, and recommend that flyers be cautioned as to the danger of the manoeuvre. Further, there are certain considerations that point to the desirability of an investigation into the special conditions attending this attitude in flight, and the Committee recommend that the Advisory Committee be asked specially to examine the questions of vol piqut flight and recovery therefrom. 46. Gyroscopic Effect of Rotating Engine and Propeller. —Calculations and experiments have been made at the Royal Aircraft Factory to determine the amount of the gyroscopic action of the rotating engine (100-h.p. Gnome) and propeller. The engine is assumed to be running at 1,200 revolutions. The amount of the gyroscopic effect depends also, of course, on the rate at which the machine is being turned. In the calculation made it is supposed that this is such that a complete circle would be described in 20 seconds. Consideration of the maximum rate probable in a sudden dip leads to a nearly equal result. The moment due to this cause is then of the order of magnitude of that which would be produced by a force of 20 lbs. acting on the horizontal or the vertical rudder. 47. The couple due to gyroscopic action will have an effect as regards (a) increase of stress, (6) steering. There is no reason to anticipate serious consequences on either ground. There is no difficulty in taking up additional stress of the amount indicated. Probably the most important consequences would arise in the event of any insecurity in the mounting of the engine. This is a further reason for attention to this matter. In its relation to steering, the effect may be compared with that of a small gust, of known direction, and should cause no difficulty to the flyer. 48. Testing and Inspection of Machines.—The Committee desire to lay stress on the importance of the carelul testing, and periodical inspection, of machines. No machine should be taken into use until after thorough examination and approved test. 49. The exact tests to be applied require some closer investiga tion. The Committee have, by the kindness of the Military Attache to the British Embassy in Paris, received particulars as to some of the tests laid down by the French authorities, and a memorandum presented by one of the witnesses gives some useful suggestions. The Committee recommend that the Advisory Committee be requested to take the matter into careful consideration. 50. The advisability of testing machines has been questioned on the ground that the test load may overstrain some part. This, however, is only a matter of properly proportioning the test load at each point to that which will produce rupture, and would no doubt be considered by the Advisory Committee in their report. 51. The Committee are agreed that it is desirable arrangements should be made for the regular inspection of machines and of their engines. For this purpose it is desirable that a sufficient number of permanent officials should be appointed— (a) To inspect and report on the machines at regular intervals to xhe officer directing the work in the air. (6) To examine and report OD every accident and repair. 52. The Committee are of opinion that the condition of the engines is of such paramount importance to the safety of pilots and observers in aeroplanes, and the engines, in the present state of development of the aircraft industry, are so various^ in design, requiring careful and frequent expert inspection, as to justify the appointment of an engineer of extensive technical experience as an Inspector of Engines, with the rank of an officer in the Military Wing of the Royal Flying Corps. 53. The Committee feel also that the lives of those who fly aero planes depend to an important degree on the skilful and conscientious manner in which the mechanics of the Royal Flying Corps carry out their work of examination and adjustment of the various parts of an aeroplane, and they wish to bring to the notice of the Lords Commissioners of the Admiralty and the Army Council the importance of ensuring that as large a number as possible of the mechanics of the Royal Flying Corps are adequately trained without delay to perform their duties in an efficient manner. The Committee realise that the organisation of the Royal Flying Corps, when matured, will render possible the training of the requisite numbers, but they suggest that, during the present stage of its development, to supplement the training establishment of the Royal Flying Corps, two or three skilled mechanics for each squadron should be specially engaged for a time to act as instructors, and to set a standard of technical workmanship, while advantage should be taken of the facilities afforded by private firms, both at home and abroad, for teaching men in their workshops. 54. Chief Conclusions and Recommendations.—The main conclusions arrived at by the Committee and their recommendations in connection therewith may be briefly summarized. (/jjGHf] (i.) The accidents to monoplanes specially investigated were not due to causes dependent on the class of machine to which they occurred, nor to conditions singular to the monoplane as such. -• (ii.) After consideration of general questions affecting the relative security of monoplanes and biplanes, the Committee have found no reason to recommend the prohibition of the use of monoplanes, pro vided that certain precautions are taken, some of which are applicable to both classes of aeroplane. (iii.) The wings of aeroplanes can, and should, lie so designed as to have sufficient strength to resist drift without external bracing. (iv.) The main wires should not be brought to parts of the machine always liable to be severely strained on landing. (v.) Main wires and warping wires should be so secured as to minimise the risk of damage in getting oft the ground, and should be protected from accidental injury. (vi.) Main wires and their attachments should be duplicated. The use of a tautness indicator, to avoid over-straining the wires in " tuning up," is recommended. Quick-release devices should be carefully considered and tested before their use is permitted. (vii.) In view of the grave consequences which may follow fracture of any part of the engine, especially in the case of a rotating engine, means should 1* taken to secure that a slight damage to the engine will not wreck the machine. Structural parts, the breakage of which may involve total collapse of the aeroplane, should, so far as possible, be kept clear of the engine. (viii.) The fabric, more especially in highly loaded machines, should be more securely fastened to the ribs. Devices which will have the effect of preventing tears from spreading should be con sidered. Makers should be advised thai the top surface alone should be capable of supporting the full load. (ix.) The makers should be required to furnish satisfactory evidence as to the strength of construction aud the factor of safety allowed. In this special attention should be paid to the manner ia which the engine is secured to the frame. (x.) Engine breakages should be systematically investigated and reported on, and the reports should be submitted to the Advisory Committee for Aeronautics. (xi.) No machine should be taken into use until after examination and approved test, and all machines should be regularly inspected, especially after any serious damage or repair. Parts of machines in course of construction should l>e inspected and passed before being assembled. • ' (xii.) Two or three skilled mechanics for each squadron should be specially engaged for a time to act as instructors and to iet a standard of technical workmanship. (xiii.) In case of any serious accident, care should be taken to preserve and identify damaged portions of the machine which may help to account for the cause. It is desirable to obtair.the assistance of the police authorities in this matter. 55. With regard to the machines already in use at Larkhill, the Committee recommend that they be carefully inspected by a skilled engineer, and, if necessary, modified so as to bring them as far as possible within the recommendations of this report, regard lieing had particularly to the points dealt with in clauses 20 and 32. 56. The Committee also desire to recommend that the following questions be specially referred to the Advisory Committee for Aero nautics for further investigation and report— (a) The general question of the stability of aeroplanes. 6) Detailed investigation of the strains and stresses in aeroplane wings, especially monoplane wings. Tests on the strength of wooden struts and beams as used in aeroplane work. (() Aerodynamic investigation ot aeroplane wings designed to have sufficient strength without external bracing. (d) Investigation into the strength of aeroplane fabrics, wounded and unwounded ; and into the effect of the application of dopes and of exposure. (e) Investigation of engine breakages. (/) The methods of testing a complete machine and the test conditions to be fulfilled. (g) Investigation into the conditions of the vol pi qui in respect to monoplanes and biplanes. In conclusion the Committee desire to place on record their high appreciation of the valuable services rendered to them in the course of their enquiry by their secretary, Mr. F. J. Selby. They wish also to thank those members of the staff of the National Physical Laboratory whose investigations have contributed so greatly t» the elucidation of the causes of the accidents. (Signed) R. T. Glazebrook (Chairman); A. E. Berriman ; R. Brooke-Popham, Major ; Spenser Grey, Lieutenant, R. N. ; David Henderson, Brigadier- General ; F. W. Lanchester; Mervyn O'Gorman ; J. E. Petavel; F. H. Sykes, Major; F. J. Selby (Secrelarv). 157
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