FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1913
1913 - 0666.PDF
L/-j.lGMT( power expenditure of less than 50 h.p. This in itself will be recognised as an extremely interesting iact that is well worthy of the close attention of those who purpose erecting wind tunnels elsewhere. It happened also that one of the first experiments conducted in the new laboratory was itself of singular interest and importance. It consisted of a lest on a scale model of a complete biplane, the original of which had been flown by Lieut. Saulnier in a special laboratory constructed by Col. Bottieaux and Major Dorand, of the Chalais-Meudon school of military aeronautics. This laboratory enabled straight line flights to be made in still air, and the aeroplane was fitted with recording apparatus that enabled the following things to be ascertained automatically and simultaneously by merely pressing a button at the appropriate time :—1, the thrust of the propeller; 2, the speed (revs, per sec.) of the propeller; 3, the air speed of the machine ; 4, the angle of inclination. The weight of the machine was, of course, known in advance. When M. Eiffel came to test the model, which was constructed to a scale of I : 14-5, he obtained a striking coincidence between his re>ults and those derived from the full-sized aeroplane. In one case, every figure was found to lie upon the same curve in both tests, and in the other case five out of seven values similarly coincided. As M. Eiffel very properly remarks, nothing could afford a beiter justification of the utility of the model research. Among the other tests made in the new wind tunnel, were those that led to the construction of the Drzewiecki aeroplane, a cuiious tail-first design, the illustration* of which will be familiar to our readers. It was constructed in order to demonstrate the principle of longitudinal stability by means of the fore and aft dihedral, but perhaps the references to it in M. Eiffel's book scarcely do full justice to the univeisal acceptance of that fundamental principle in aeroplane design. It is, in fact, curious that this principle, which is perhaps more completely accepttd than any other, is continually being exploited in all manner of special guises, which althougn novel in themselves, derive whatever vjrtue they may possess from a principle that is now In-coming as old as the hills. The practical realisation of the principle of the fore and aft dihedral depends on the leading plane of an aeroplane having a heavier loading (lbs. per sq. It.) than the tail plane. In the case ® ® The Burton-orj'Trent Meeting. Arm si 1ST, 2nd, 4th (Bank Holiday), and 5th have been decided upon :is the dales of the meeting at Burton-on-Trent which is being organised by Mesrs. llandley I'age, Ltd. There will be two or three races each day, and the following prizes will be offered:— Burton to Repton and back twice (4 miles each way). Prize Z25. JUNE 28, I9I3- of a tail-first type of aeroplane, the main planes occupy the position of a tail plane, and must be less heavily loaded than the leading plane. In the case of an ordinary aeroplane, the main planes, being in front, must be more heavily loaded than the tail. The distribution of the weight of the machine is such that the aeroplane is balanced fore and aft in its normal flying attitude. If the attitude of the machine changes, by a small amount, so that the angle between its axis and the relative wind is now, say two degrees less than formerly, then both the main planes and the tail plane will have suffered a similar diminution in their angles of incidence. If the effect of this diminution is an equal loss of lift on both planes then the proportionate loss is less on the leading plane than on the tail plants, because the leading plane has the higher initial loading. The consequence of this difference is that the tail end of the machine tends to fall, and thereby to restore the normal attitude of the axis of the machine in flight. If there is any difference in the absolute loos of lift on the two planes for a common change in the angle o incidence, it is, of course, important that the difference should Lot be such as to destroy the above principle. But from the evidence of practical aeroplane construction, it is apparent that there is to difficulty in acquiring a sufficient difference in initial loading lo neutralise any individual differences in the characteristics in the wing sections employed for the main planes and the tail. In this matter the tail-first type of aeroplane has the advantage of affording a wider range of attitudes for the stabilising organ. The chief consideration of the designer is, of course, the main plane, and if this happens to be very lightly loaded, the latitude for the adjustment of the tail plane so as to be still less lightly loaded is small. On the other hand, when the stabilising member is in front, it will have to be more heavily loaded than the main plane, and the latitude for doing this is, by comparison, unlimited. Eiffel's later wotk at Auteuil has been directed towards the testing of propellers, for which he has a very ingenious apparatus. His propellers are tested in the wind tunnel, the draught being adjusted to the speed of flight. The propeller is driven from over head by a vertical shaft and bevels. The motor that drives the propeller, and al.10 supports it, is itself supported upon diaphragms, so adjusted that they record by means of gauges the thrust and the torque. ® ® Altitude competition. Piize cup £25 (presented by Messrs. Bass and Co.), with £75 in gold. Cross-country race to Atherstone and back (distance 18 miles each way). Prize £50. Bomb-dropping competition, quick-starting competition, and passenger carrying will also be carried through. pu3ie 1 The ground on which the meeting is being held is the one on which the successful meeting was held three years ago, and is beine lent by Messrs. Bass and Co. 7*^ & Photo, by Butler and Ward, Chiswick Visit cf the Irish Millers to Hendon Aerodrome, Thursday, last week.—Around the tea tents. 692
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
