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Aviation History
1929
1929 - 1085.PDF
FLIGHT, MAY 23, 19291 East^Africa as an agricultural country of wide spaces, one is inclined toexpect rather more scope for this type of work than actually occurs. Coffee, which is the principal crop of Kenya and parts of Tanganyikaand Uganda, grows in the highlands, usually in relatively small areas, and almost invariably in very broken country difficult for aeroplane spraying opera-tions. Coffee is not at present attacked by any pest which is susceptible to surface spraying. Cotton, the principal crop of Uganda and parts of Tanganyika, is entirelynative grown in very small plots entirely unsuited for treatment by aircraft. The system of cultivation which makes it unsuitable for aeroplane treatmentmakes it easy to apply the more drastic method of burning infested crops, which is now enforced.Sisal, grown largely in the lower lying level areas in very large plantations, Ideally adapted for aeroplane spraying, appears to be impervious to anypests. Maize, a rapidly increasing crop in Kenya, is attacked by the mealy bug,which, however, buries itself in the cob and cannot be reached by surface spraying.An opportunity for experimental attack by aircraft did present itself in the fcry serious locust invasion of Kenya, which took place in 1928 and the earlypart of 1929. While it should be possible to do valuable work with aircraft in a locust invasion, the technique of attack has certainly not been developedto the point where any certainty of success can be promised. Control of Flying The International Convention for Air Navigation applies to British Possessions by virtue of the signature of Great Britain. Certain sections of the Air Navigation Act of 1920 were applied to the Crown Colonies and Protectorates by the Air Navigation (Colonies and Protectorate) Order in Council of 1922. In 1927, the Air Navigation (Colonies, Protectorates and Mandated Territories) Order in Council, 1927, applied many of the detailed provisions of the home Order in Council to the Colonies, etc., while it left to the Governor discretion on many points, which might be affected by varying local conditions, and gave him power to make directions to amplify and give full effect to the terms of the Order in Council. ('.Air Navigation Directions.—In 192S, directions were drafted in Kenya, Uganda and Tanganyika, and in Kenya they were put into force. They are drafted on somewhat similar lines to the British Air Navigation Directions. The main differences in the Order and Directions from those in force in Great Britain are :— (1) Type Certificate of Airworthiness.—No provision is made. (2) Periodical Inspection.—For the 24 hourly inspection of aircraft flying for hire or reward is substituted a weekly inspection, except in the case of aircraft operating on a regular service. (3) Pilots' Licences.—" A " licences only may be issued by the Governo* ; " B " Licences may be renewed. The Directions are drafted on fairly comprehensive lines, and contain provision for the temporary relaxation by the Governor of any of the conditions where it is clear that local conditions make it impracticable to carry them out. This course was considered preferable to establishing a lax system to fit the existing facilities for control in a Colony, with the inevitable necessity of tightening up the system later on. Air Board.—An Air Board has been established in each territory to advise the Governor on matters of principle and policy arising out of the regulations. While the Board may have a permanent existence, its avowed purpose is to distribute the responsibility which would normally be borne by a special department having experience of the administration of aviation—until such a department is justified. The Board consists of the heads of those depart- ments having some interest in aviation, headed by the Colonial Secretary or Chief Secretary. A Registrar has been appointed as provided in the Order, and his functions will include all the routine business of administration.Function of the Aero Club in Control.—Use is being made in Kenya of the Aero Club of East Africa in a number of ways. The club has been appointedprovisionally as a technical advisory body to the Air Board. It has under- taken the examination and testing of candidates for " A " licences. Twoof its representatives with previous experience are being instructed in the methods of aircraft inspection, with a view to carrying out this duty, andrecommenjing to the Air Board the renewal of Certificates of Airworthiness. A subsidy has been granted to the Aero Club by the Government of Kenyato enable it to employ a qualified ground engineer, who will be available for the " signing out " of any aircraft requiring it. His headquarters willbe in Nairobi, and his duties will include the management of the new Nairobi aerodrome. In addition to this, arrangements have been made with theKenya-Uganda Railway to find posts for two other mechanics with ground engineers' qualifications. These will be available for spare time work onaircraft. It will be possible, therefore, for aircraft operators who cannot afford to employ ground engineers of their own, to have their aircraft inspectedat the intervals required by the regulations, and, at the same time, the path of the private owner in the matter of overhauls and repairs will be greatlysmoothed. Special ConditionsHaving now surveyed the field, we may review briefly the special conditions which aircraft operators have to face in East Africa. With the advance inaeronautical design and the technique of aircraft construction which has taken Plan since the war the problem of operation in the tropics is not such abugbear as it. was. Certainly to-day there is no excuse for that legacy of the war, the belief so widely held that there is something peculiar and myster-]OUK in the conditions in East Africa, which makes it impracticable to operate aircraft satisfactorily or even safely. No better proof to the contrary isneeded than the constant stream of " Moths," " Avians," and bigger craft Bitting up and down to the Cape apparently quite normally, though actually,we know, lacking some of their home performance. Temperature.—Data concerning temperature, humidity and pressure aregiven in the section dealing with climatology in this paper. It will be seen that no conditions of extreme temperature have to be faced. While freezingtemperatures are sometimes experienced in the highlands, a temperature of 100" F. may be looked on as the normal upper limit. This, however, issufficiently high to affect the take-off and landing run adversely. Humidity.—While conditions of extreme humidity are only met with on-he coast and to a lesser extent around the lakes, e.g., in Uganda, it will be seen that in the dry season conditions of extremely low humidity may be encountered, and are normal in such regions as the Northern Frontier Province°i nenya. Aircraft may therefore be subjected to both conditions alternately probably the worst conditions for wooden aircraft. Shrinkage and warping°' spars, ribs and longerons, with the attendant slacking off of fittings, is a -erious item of maintenance in a dry climate. If to this is added a periodical Change of Address BURCH'S, the well-known R.A.F. tailors, have had tom°ve to new premises, owing to alterations in the Strand, wllere, at No. 401, they have been established for over subjection to moist conditions, a further detriment to the use of woodemaircraft is introduced, particularly where glued surfaces are concerned. The more serious of the two factors, however, appears to be the dry condition,owing to the change in strength factors of the timber on loss of water content. Pressure and Height.—The whole of East Africa lies within the tropical low-pressure belt, but it has been shown that the variations of pressure at any place are extremely small. Pressure is therefore practically a function ofheight, and this, it is abundantly clear, is an all-important factor in East Africa, affecting as it does the performance of an aircraft in take-off, landingrun, climb and speed. Nairobi, at a height of 5,500 ft., has been given as a typical example with a minimum relative density of -81. While this expressessufficiently well the normal condition in the highlands, more extreme con- ditions are met with, for example, on the Uasin Gishu Plateau (Eldoretand Kitale) where the altitude is 7,000 ft., and other isolated places where operations may have to be carried out at an altitude of 8,000 ft. As far aspossible, the increased take-off and landing runs are being allowed for by increased size of landing grounds. From a recent investigation of the effect of low-pressure and high tempera-ture on the take-off and landing run of aircraft carried out by the Royal Air- craft Establishment, it is calculated that the increase in run required by anormal aeroplane at Nairobi in the dry season with a temperature of 90° is as follows :— Increase per cent. Take-off run SOLanding run .. .. .. .. .. .. .. 23 Severe dust devils and smoke from bush and grass fires are referred to unde r" Climatology," and need only be mentioned here as special conditions. Insect Pests.—A much feared enemy of the wooden aircraft, without muchjustification, is the white ant. The white ant occurs in different forms in the whole of Africa, from the southern Sudan to Rhodesia. He is, in all cases thatI know of, a timber borer, but the important fact which is usually lost sight of is that he does his work under special conditions. He loves darkness, comesout under cover of night or twilight, and, in attacking a tree or a post, builds tunnels of mud along the ground and up the trunk of the tree. A whole forestof trees may be encountered, stained to a height of 10 ft. from the ground with the deep rich red of the laterite soil, carried there by the white ant in hisoperations. The process is slow, and it is not until a house is left unoccupied for a considerable period that the white ant invades it and does the damage tofurniture, trunks, etc., which makes him so much feared. To a normally maintained aircraft, therefore, the white ant is not a factor to be very seriouslyconsidered. The habit of the white ant of building ant-hills which vary in size andshape from the giant hills 15 ft. high found in Rhodesia, to the small mole heap type found on the Iringa Plateau, and the strange chimney formationsfound in the southern Sudan—this habit is much more a danger to aircraft than his timber boring propensities. Fortunately it appears that when ant-hills are continually destroyed, and particularly when the destruction goes below ground level and the queen is disturbed, the ants forsake the nest, and acontinuously maintained landing ground, therefore, costs successively less each year to maintain on this account. The same thing also applies to thegrowth of bush on a landing ground, which is continuously cleared. The white ant is not the only boring pest to be considered. The borerbeetle is common in the southern Sudan and northern Uganda. His ceaseless activities in the wooden beams of one's grass banda may be listened to allnight, while periodically he ejects a fine stream of wood dust on to one's face through the minute hole by which he enters the beam. His efforts result inquite a short space of time, in an outwardly sound piece of timber, which is completely hollow inside. Again, the conditions of his working are much morelikely to attract him to the wooden frame of a hangar than to the wooden members of an aircraft frame.Cases are not unknown where the propensity of the innumerable bees of the country for nesting in small holes have attracted them to the pitot tubeof an aeroplane, with disconcerting results for the pilot It is a good rule to stop up the pitot tube when the aircraft is on the ground, not forgetting theprecaution of tying a red rag to the stopper, in case the cure should be as- disastrous as the disease. The prolific life of the mangrove swamps of the seaboard of East Africasuggests that additional precautions to keep the floats and hull bottoms of seaplanes clean and protected will be necessary.Special Type of Aircraft Required While in East Africa, as elsewhere, different types of aircraft will be requiredfor different types of work, one or two points may be brought to the notice of designers.The climatic conditions suggest immediately the desirability of all metal construction in place of wood.The high altitude of operation calls for some increase of power in the normal light aeroplane, to give it approximately the same carrying capacity andperformance. The large areas of bush to be flown over point to the desirability of thethree-engined aircraft, even in small sizes, to give absolute freedom of flight over the whole country with comparative safety.Taking into account the economic features, the most useful type of machine for which there should be a demand in the near future, is a cabinmachine for four passengers with baggage space. The machine should be fitted with three engines, and on account of the high altitude of operationshould be designed to fly on any two engines at 7,(100 ft. without loss of height. It should have a cruising range of about 300 miles in still air. Such a machineappears to be one that will meet with a demand in all colonies or similar partially developed countries, and it is good to note that the type is nowreceiving the attention of British designers. With such a machine one of the last obstacles to aircraft operation inEast Africa—high or prohibitive insurance rates—should largely disappear. Closer Union Commission Report While the Closer Union Commission did not specifically study aviation iarelation to the development of the East African territories, their report is a document of such far-reaching importance in this connection that it is worthwhile quoting in conclusion their main reference to the subject, as showing the probable trend of development :— " Great possibilities for the future of communications as a help towardsadministrative union lie in the development of air routes. A service of communications by air cannot be organised save by the common effort,administrative and financial, of all three territories." f am indebted to Mr. S. G. Champ, of the Air Ministry, for very great helpin the preparation of the material, diagrams and slides used in this lecture. <$> <•>40 years. They have now removed to more modern and commodious premises at 33, Bedford Street, W.C., right opposite the Post Office. We trust "FLIGHT" Readers, Service and Civil, will note this change. 431
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