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Aviation History
1913
1913 - 0235.PDF
FEBRUARY 22, 1913. The name ana,address (/ycHT) CORRESPONDENCE. oj the writer (not necessarily for publication) MUST in all cases accompany letters intended fer insertion, or containing queries. Correspondents communicating with regard to letters which have appeared in FLIGHT, would much facilitate ready reference by quoting the number of each letter Aeroplane r ngines and R.A.F. Tests. [1726] It may be useful that constructors of engines intended for aeronautical purposes should be informed that I am prepared to test at the R.A.F. anysuitable engines. An impression having arisen, perhaps from the terms of the Alexander Prize Competition, that such engines must be submitted to a 24 hours' full load test in order to be considered, I beg that you will assist in removing this impression. It is a goal to be aimed at that such an engine shall be capable of running without overhaul for a total of 24 hours, and it is to be appreciated that aeroplane conditions involve running up somewhere about full load during the major part of flying—differing in this from normal motor car conditions. Builders of aeronautical engines are invited, and all facilities will be given to them, to demonstrate their engines by test at the R.A.F. Petrol, oil, and labour will be provided without cost, and the test bench appliances will be put at their disposal, subject only to the presence of a skilled mechanic to represent the firm putting forward their engine, and under the firm's responsibility for the test and any damage or accident which may occur in connection with the test. It is useful to secure that the weight shall not exceed 4 or 5 lbs. per brake h.p., and the brake h.p. in question is that h.p. which the engine will develop as useful h.p. on a 5 hours' test. It is as well that designers should realise that propellers of usual diameter run at from 900 to 1,200 r.p.m. according to the engine, and at normal full load, and that when a speed as low as 900 r.p.m. is given it is obtained by gearing down to the propeller shaft (naturally weight allowance is claimable for this). One of a type of the engines now in use has in most cases (viz., one British and three foreign) been run from 20 to 24 hours without mechanical damage or overhaul and without compulsory stop. I can provide a wind-tunnel over the brake instrument, giving about 30 r.p.m. wind, or alternatively the engine may be submitted with a screw or fan such that it affords its own cooling. Where an air screw is used to develop the h.p. r.p.m., it will be necessary that it shall be handed over to be calibrated, and so obtain a measure of the power consumed by such screw. Fuel and oil consumption will be measured. Any further particulars will be given on request, and a statement of the performance, weight, h.p., speed, endurance, consumption, which is claimed is invited, whether or not the above desiderata are reached. MERVYN O'GORMAN. Supt. R.A.F. The Wulffing Airship. [1727! In view of the apathy of the Government and the English nation in general to airship matters, chiefly owing to the non-existence of any (apart from the small Army dirigibles), I beg to place before your readers some particulars relating to an airship with several unique features, patented in this country by Mr. Wulffing, a German engineer. Essentially Mr. Wulffing employs a rigid form of construction. This, however, is of a modified nature, which is such as to combine the advantages of the rigid system with those of the non-rigid type. The hull is built up on a skeleton of steel tubes; these steel tubes can be made exceedingly light, and can be built either fusiform or fish shaped hull as desired. The steel tubes converge at the l»w and stern, where they are joined together by a metal nose-piece and tailpiece. The steel cable running horizontally from bow to stern knits the whole structure firmly together, anil renders it absolutely rigid. The skeleton thus formed is covered with an outer covering of fabric ; within the lifting gas is contained either in a single envelope—which may be separated by partitions—or in a series of interior balloons. The base of the hull is left flexible by the omission of two or more steel tubes that would normally occupy this position ; the latter are replaced by elastic strands, thus when the gas expands owing to a decrease in the atmospheric pressure or increased temperature, this elastic portion of the envelope will be distended, thus preventing the loss of gas which would otherwise take place. The engines are six in number, and are mounted in two sets of three, one engine being mounted at the bow with two engines immediately in its rear, carried on outriggers extend ing upwards to either side of the hull ; a similar arrangement, but in reversed order, is adopted for the rear motors ; each set ot engines is mounted on a separate girder platform. The passenger car, completely covered in, is situated l>etween the two motor platforms, and works in a ball-race at either end, so that the shock of landing is thrown neither on to the rigid car nor on to the power plant when resting on the ground or on the water, for which also it is provided. In flight the motor platforms and car are locked rigid ; the propellers are well clear of the surface ; these engines work independently, and the propeller in each case is mounted direct, thus saving any loss due to transmission. The following form the main features of the dirigible under consideration : Length, 325 ft. ; master diameter, 50 ft. ; average diameter, 35 ft. ; capacity, 350,000 cubic ft. ; gross lifting power, II tons ; total weight, including engines, car, &c, 6 tons ; net lifting power, 5 tons. As the total lift amounts to 24,640 lbs., the net lifling power amounts to 11,200 lbs., or about 50 per cent. ; the best Zeppelins have only al«jut 30 per cent. I enclose two drawings, one in reference to the above description, the second is to do with a smaller ship (44 by 279 ft.), which it is thought would 1* better to start building on account of it costing less money, which for this purpose is hard enough in England to get ; but constructionally both are exactly the same. The advantages of the Wulffing airship over the Zeppelin are : This airship is absolutely rigid, but the construction is so light that if, for instance, we build a ship of the same cubic capacity as the Zeppelin we have double the size of car for passengers, and 50 per cent, more motor power ; still 80 to 100 per cent, more net lifting power than the Zeppelin. The higher motor power enables us to obtain greater speed (by a size equal to the Zeppelin) of 60 to 70 miles per hour. The higher net lifling power enables us in time of war to take in more petrol for longer acting radius ; quick- firing guns with plenty of ammunition, and an additional platform •9 The principal feature of the WulfHng dirigible lies in the construc tion of the gas-containing hull; he has abandoned the lattice girder type of framework, and has obtained his increased lifting power principally in this direction. above the aerostat for observation purposes, and quick-firing gun ; larger crew, wireless telegraphy, &c. ; and for private use good income can be earned by passenger carrying, of which a good number could be taken, about double the amount of the Zeppelin ; 241
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