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Aviation History
1912
1912 - 0406.PDF
Conducted by V. E Replies to Queries, April 20th issue. MR. C. IAN BURRELI. writes as follows:—"(i) Re twin screws)- This question is of comparative unimportance ; however, should one propeller cease to revolve or drop off a model, with arrangement (a) it will make the better landing of the two owing to the reactionary forces of the remaining propeller helping to right the machine. (2) is of greater importance ; to my mind neither arrangement is really satisfactory, for unless the wheels are placed a considerable distance from the C.G., uneven ground will tend to make system <I) tilt forwards (driving the nose into the ground), and system (2) backwards (causing the profilers to come into contact with the ground), in both cases bringing the machine to rest. To overcome this by placing the wheels a good distance from the C.G. too much weight is placed on the skid, and it will act as a serious drag. I have personally found that two wheels just in front of the C.G., combined with both and front rear skid, give a much better result than either system discussed so far, but I find three wheels give a still better result—two wheels some three or four inches in front of C.G. and the third under the propeller." [Compare system shown in steam model illustration.] Mr. W. H. Norton (Chairman Reigateand Kedhill District Ae.C.) also writes : " The matter has been discussed by some of our members (re propellers). Personally, I think it is best they should revolve outwards on twin screw models, for we know that with a single screw the torque is the opposite way to which the propeller revolves : therefore if they revolve outwards on a twin screw model, it would tend to depress the back end of the machine and assist the elevation. But they have been tried revolving inwards, and really I see no difference in the results. On my own models 1 have them revolving outwards for convenience, as I have a duplex winder which winds from the apex of the triangular frame and it is handiest to wind thus. A\ chaiMI, I prefer No. 1 drawing, as I believe it forms a straightcr running on the ground and also a rear skid protects the propellers." Mr. P. C. Nosworthy, referring to the same matter, says : *' In a twin screw model of l-i-Pa-o type, if the ' tops ' of the propellers revolve out wards, the propellers will, whether the machine is stationary or in motion, tend to lift the machine, my explanation being that the propeller ' beat' will act with the greatest force on the machine when the blade is farthest from the C.G. I arrived at this decision after testing a (I-I-P2-O) model having the propellers situated verticallyabove the other and revolving in opiwsite directions. I then found that the model circled in the direction in which the ' top' of the upper propeller revolved. It is therefore most efficient for the propellers to revolve outwards." (AV Query 2). Since a skid is more likely to stand a severe shock without derangement than the wheel chassis, it had better be placed Ns-iled, bound an.d glued Bound. * £W4 1" J 5 round, carve nailed, OTV . JOHNSON, M.A. forward where the brunt of the landing shock has to be taken. Therefore figure 2 is the better combination. (Re Query 3). The large disturbance in the water will be caused by the ducks using their webs as a break to their speed while alighting. Protectors. Mr. W. E. Evans (Hon. Sec. Paddington and District Ae.C.) writes : " I entirely agree with your remarks in to-day's FLIGHT re ' protectors.' You will have my cordial support in the matter, and I will bring it before my committee." In a later communication we learn that the above club have made it a rule (to come into force after May 1st) that all members are forbidden to fly without protectors. Mr. H. F. Holmon (Dover) writes : " I think your notes concerning protectors for model aeroplanes are quite appropriate and timely ones. Although I have never experienced the sensation of receiving a model aeroplane in the neck at about 25 m.p.h., I should certainly not like to, and I am sure that spectators at model ' meets' must be of the same opinion. I enclose a sketch of a protector I have just fitted to a 34-in. A-frame. It is made of two pieces of fVin. cane, and, as you remark, ' serves the purpose of a skid quile admirably.'" The Gordon Jones Biplane. We publish this week an illustration of a very interesting model— interesting for two especial reasons. In the first place it is a Holman's sketch, showing protector. model aeroplane 406 The Gordon Jones all-steel biplane, biplane (which we would like to see far more in evidence), and in the second place it is built entirely of steel (silk surfaced), and is therefore, practically speaking, unbreakable. Steel, although so far as the average amateur is concerned, is possibly more difficult to work and manipulate than wood, but it does undoubtedly possess certain well-marked advantages over it. Amongst them one of the chief is a marked diminution in head resistance owing to the lessened sectional area of steel compared with that of wood of equal strength. Mr. Gordon Jones is well known as a builder of models which have won medals and prizes both at Olympia aero shows and in open competitions. Undoubtedly, steel will be far more largely used in the model of the future than it has been in the past. Steam-Driven Model. As will be seen from the two illustrations, we have completed the model to carry the steam plant made for us by Mr. H. H. Groves, and we are only awaiting the first favourable day to try the same in actual flight. The total weight of the model (without fuel) is 3-lbs. iA-ozs. The C.G. is about 2 ins. in front of the main plane. The only difference made in the model since the photographs were taken is that the length of the elevator has been increased by two extensions of about 2 ins. each. The span of the model is 5 ft. 6 ins., the length 4 ft. 5 ins. It will be noticed the landing-chassis is of a decidedly novel character—being arranged, so far as possible, that the chief forces are in tension. The combined wheels and skids
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