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Aviation History
1919
1919 - 0022.PDF
JANUARY 2, 1919 THE REPORT OF THE CIVIL AERIAL TRANSPORT COMMITTEE APPENDIX II. Interim Report of Special Committee No. 2. . Introductory. The Special Committee were requested to advise as to the practical possi bilities of aeronautics from a scientific and technical point of view, with special reference to certain detailed subjects which of necessity call for con sideration in connection with this branch of the Main Committee's enquiry. 1 • reui e detalIed subjects are dealt with, the Special Committee think it advisable to emphasise some general considerations. Since aeronautics represent m their civil and commercial aspect an untried field of enterprise, it is impossible to arrive at very definite conclusions in many of the subjects considered by the Special Committee, particularly owing to the fact that the technical and scientific data at present obtainable are applicable to aircraft used only for naval and military purposes, and to conditions of flight varying widely from those which will prevail after the War. In this connection, it should be remembered that the whole trend of design has been towards efficiency m the fighting machine, and, consequently, there has been little opportunity for research and enquiry into possibilities of the commercial uses of aeroplanes and airships. The same considerations apply to those branches of the Special Committee's enquiry which deal with the practical running of aerial services on commercial lines. with regard to the detailed subjects assigned for consideration by the Special Committee, these have been in most cases referred either to small sub-committees or individual members of the Special Committee, and the present report is intended to present the conclusions which can be drawn from the materials supplied in this manner. The Main Committee will observe that it has not been possible as yet to cover the whole field of enquiry, but it hns been thought that the conclusions at present reached can con veniently be summarised in an interim report. It is, therefore, proposed to deal with the different items of the terms of reference to the Special Com mittee in order. I. The possibilities of the employment of aircraft at present and in the near future in transporting passengers, mails, and parcels, with the estimated limits of their range, weight, carrying capacity, and running costs, based on the assumption of reasonable State regulation of air traffic, and the probability or otherwise of the use of privately owned aircraft by individuals for pleasure or other purposes. , Types of Aircraft. ?i.eo7* tBe Possibilities of the employment of aircraft for purposes A- transport of passengers, mails and parcels, the Special Committee directed an enquiry* to be made as to (i) four existing types of aeroplane, and (11) rigid airships. These were made the subject of reports by Col. O Gorman and Mr. Bairstow, as to the aeroplanes, and by Wing Capt. Mait land, as to the airships, which are appended to the present Report as Appen dices A and Bf. With regard to aeroplanes, the following four types were selected, viz. :— (i) The Handley-Page, with 250 h.p. Rolls-Royce engines, and the " America " flying boat. (ii) The de Havilland 4, with 250 h.p. Rolls-Royce engine or 230 b.p. B.H.P. engine. (iii) The R.E. 8, with the R.A.F. 150 h.p. air-cooled engine. ftv) The Sopwith " Pup," with an 80 h.p. Le Rhone engine. These types were selected to cover the whole range of well-known machines wl j°a "fw to estimating the possibilities of transport from existing data. Col. O'Gorman and Mr. Bairstow presented the following general con clusions to the Special Committee on the hypothesis of aerial transport in still air. A. It is profitable, so far as fuel consumption is concerned, to fly high. B. It is profiatble, so far as fuel consumption is concerned, and so far as the cost of aeroplane construction is concerned, to use a heavy loading of the wings. C. Since high-wing loading means fast alighting, the provision of first-class grounds will, it is considered, lead to economy of transport. Your Sub- Committee contemplates landing speeds upwards of 60 m.p.h. This does not refer to seaplanes or flying boats. D. High speed of flight is in direct conflict with great weight carrying capacity. E. It follows from D that, in selecting the flying speed of the aeroplane to be used, a compromise must be struck between the value of (a) fuel and labour economy and (6) speed or time saving. F. As illustrating E, a lightly loaded aeroplane, such as is commonly used now, cannot possibly at 120 m.p.h. (low level speed) fly 1,000 miles, that is to say, there will be no lift available to carry even the flyer; whereas, at 80 m.p.h., no less than 30 per zent. of the gross weight of the aeroplane becomes available for crew and commercial load. G. The comparatively small importance of rapid climbing in commercial air work will make the possibilities of combining high speed and weight- carrying much better than those of the modern service aeroplane. H. The cost of production of aeroplanes (taken over the range of varia tions of type presented by the four service aeroplanes selected and based on quotations for large quantities) is roughly proportional to the total crew and useful load carried ; and this in turn is equally proportional to the totai gross loaded weight of the aeroplane, viz., at war prices about £900 per- every 1,000 lbs. of gross weight. With regard to conclusion F, it was pointed out by way of explanation in a supplementary note (at the end of Appendix A) that a comparison is drawn therein not between two performances of one machine, but between performances of two different machines, one designed to fly at 120 m.p.h., and the other at 80 m.p.h. Particular attention is drawn to the tables annexed to this Report. These conclusions were discussed by the Special Committee, and a further report was asked for from Col. O'Gorman and Mr. Bairstow as to the effect in a 1,000-mile journey of an adverse wind on the choice of the flight speed of an aeroplane. This further report is appended as Appendix C. The table attached to this further report sets out the available weight of crew and commercial load per r,ooo lbs. of total loaded weight, as affected by adverse and favourable winds over the journey nam< d. In making any definite recommendations as to commercial transport by aeroplane the Special Committee have felt that, for the reasons stated in the beginning of this report, it is impossible at the present stage to fix upon any particular type, and, therefore, they present the following general conclusions from the technical point of view. Conclusions as to Aeroplanes, (i) That for commercial success speed is probably the most material f actor. * With regard to the types of aeroplanes selected, it should be noted that this enquiry was directed in July, 1917. t Not printed. (ii) That for commercial success the speed needed depends very greatly on the conditions of competing methods. Between large centres connected by direct high speed railways, ground speeds of 100 m.p.h. are desirable, but for linking places between which the railway service is slow or inter rupted by sea crossings, lower speeds will be found commercially practicable. (iii) That, at present, stages of about 500 miles would be the normal limit, but that it will be desirable from the commercial point of view that stages should be as long as possible. (iv) That it is desirable as speedily as possible to develop the existing facilities for night flying, especially for the carriage of mails. (v) That heavy loading is necessary for commercial success, but, since this will involve a high landing speed, development of land and air brakes is necessary. (vi) That in view of certain disadvantages of high landing speed, efforts should be made to keep loading as low as possible consistently with securing a commercial rate of speed and to provide for aerodromes and landing places possessing the best possible surfaces, and that it may well be hoped that future inventions and improvements in design will enable a lower landing speed to be attained without sacrifice of flying speed. A irships. With regard to airships, the report of Wing Capt. Maitland is appended to this Report as Appendix B. The Special Committee desire to draw special attention to the fact that in airships above a certain size the proportion of available lift, i.e., crew, fuel, ballast, passengers and merchandise, to total weight increases rapidly, rising to as much as 50 per cent, in the case of a rigid airship with a gross lift of 60 tons, of 2,000,000 cubic feet capacity, and, therefore, from the commercial point of view there are obvious advantages in having airships of large size. Further, the conclusion can be drawn from that report that increase in size can be readily accompanied by increase in speed, as the weight of additional engines would occupy a very small proportion of the extra lift. The proportion of disposable lift in the case of non-rigid airships is less, at least in the case of non-rigid airships of the largest size at present known. The Special Committee have come to the conclusion that for commercial purposes the rigid type offers certain advantages over the non-rigid. In a further report (Appendix D*), Capt. Maitland works out some valuable statistics as to the effect of adverse wind and ascent in a 1,000-mile journey. Prime Cost. It is practically impossible to give any satisfactory estimate of running costs of either type of aircraft from existing data. With regard to the prime cost of machines, Appendices A and B contain curves showing the relation of gross weight to cost and useful load to cost, based on approximate war prices. General figures relating to cost must be considered as indicative only ; the weight of an aeroplane is not a definitely fixed quantity, and the amount of commercial load depends on the length of journey. An upper limit to the amount of commercial load is given in Appendices A and B under the name of " disposable load," this term including both crew and fuel. A lower limit is obviously zero when the journey is so long that the whole of the " disposable load " is absorbed by the crew and fuel. Figures qualified as above are :— Prime cost Prime cost per lb. of per lb. of Prime cost gross disposable per lb. of weight. load. commercial load. Aeroplane (high speed) 18s. 40s. Upwards of 40s. Aeroplane (low speed) 18s. 30s. Upwards of 30s. Airship (rigid) .. 9s. 18s. Upwards of 18s. Mail Services. The question of the carriage of passengers or of goods has not yet been con sidered by the Committee except from the technical point of view of the range and weight-carrying capacity of aircraft generally, but the Committee hope at an early date to report further on this important branch of their subject, and on the closely connected question of the probability of the use of privately-owned aircraft by individuals. In regard to what follows with respect to air mail services it should be understood that the Committee consider that in so far as the useful load-carrying capacity of the aircraft is not fully occupied by the transportation of mails it should be employed in the conveyance of passengers and even of small parcels of valuable goods. It has been pointed out above that it is desirable from the commercial point of view that stages should be as long as possible. This principle is illustrated with peculiar clearness in the case of mail services. A London-Paris air service, for example, should be effected in 2| hours, or less, as against, say, seven hours by the land or sea route. An air mail service would here enjoy a very evident advantage as compared with any other. With longer Con tinental flights, such as that from London to Paris, and then on to Turin, greater savings of time should be possible as compared with existing means of communication. In the case of the Italian mail, the time saved might amount to as much as a day. The longer the flight the more important is the time saved, and, consequently, the better are the prospects of an aerial mail service. There is, for example, nothing impossible, given the proper facilities, in sending mails by air from London to Calcutta in four days, as against 16 days (minimum), or from London to Johannesburg in six days as against 19. When the importance to business of full and rapid com munication, and the great cost of trans-ocean cabling is borne in mind, it appears perfectly reasonable to anticipate that people will be willing to pay a price per ounce for letters carried by aircraft sufficient to make these long distance air mail services commercially profitable. A cable message of 100 words from London to Johannesburg to-day, at 2s. bd. a word, costs £8 10s., and 24 hours at least usually elapse between the despatch of a message from London and its delivery to the addressee. A letter of 5,000 words need not weigh more than an ounce or two. If such a letter could be sent in six days, even at 2s. 6d. an ounce, the saving in cost would be enormous, and the extra time taken by this means of communication as compared with the cable would in many cases be more than compensated for by the avoidance of the risk of misunderstanding inseparable from the use of the necessarily abbreviated language of cable messages. The case is naturally different as regards air mail communications within Great Britain. In the case of services from London to large provincial towns, i t may be said to require a flight of at least three hours, at an average, say, of 100 miles an hour, for the speed of an air-mail service to reveal itself and for this speed to offer a sufficiently marked saving of time over land transit, remembering that one must reckon the time taken in establishing the land connections of an air service. When an oversea journey is made, such as the passage across the Irish Sea in a flight to Dublin, the saving of time offered by an air service is much more evident, and the same holds good in the case of cross-country routes, e.g., from Cardiff or Bristol to South- *_Not printed. 2*
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