Flight, January 1930

THE "TAUBE" REVIVED
Igo Etrich Incorporates Old Principles in New Machine

   AMONG the earliest German experimenters a wing form was popular which had been derived from a study of the Zanonia plant's winged seeds. The early German machines ДальшеMore>>> incorporating this wing form were given the general title "Tauben" (pigeons), presumably because they had, at a distance, somewhat the appearance of a pigeon wing overhead. The likeness to a pigeon was, however, far from striking. In plan form the wings of the Taube machines were characterised by a rounded wing tip, the trailing portion of which projected considerably aft of the trailing edge of the main wing. These flaps were given a twist so as to form not only a negative incidence in relation to the rest of the wing, but also a negative camber. The object of the arrangement was, of course, stability, chiefly lateral, but also, probably, a certain degree of longitudinal stability due to the fact that the projecting wing tip flaps were aft of the main wing to some extent. It may be recollected that Mr. Handley Page in this country, and about the same time, achieved similar results with his crescent-shaped wing form in which the wings tapered both in plan and thickness, while there was a decided "wash-out" in incidence towards the wing tips. In the "Tauben" lateral control was by flexing the trailing edge wing tip flaps.
   Among the Austrian pioneers whose early work on “Tauben" attained considerable success, was Herr Igo Etrich, the "Etrich Taube" becoming fairly popular. One of these machines was purchased by the British Admiralty in 1912 and was flown by the Eastchurch pilots.
   If our memory is not at fault, the "Tauben" did in point of fact achieve the "automatic stability" claimed for them, but the price paid for this was somewhat high. It is to be assumed that the drag of a wing which carries at its extremities large trailing edge flaps upturned to give negative incidence and camber must be higher than the drag of a "parallel" wing. Also the early "Tauben" were relatively heavy, in spite of the fact that they had what may be described as biplane wing bracing: Some two or three feet below the wing was a boom running out to the wing tip forward corner, and connected to the spars of the wing structure by struts, the girder being cross-braced with wire. This undoubtedly added a good deal of drag to a wing which probably already had a fairly high drag, and so it was scarcely surprising that the "Tauben" were somewhat slow and stately machines, and that when the war came they were supplanted by faster types which had not, and were probably not desired to have, the same "automatic stability."
   For the private owner-pilot, if he is not in a hurry and does not regard himself as a particularly clever pilot, the stable machine might, however, be worth studying once more in an effort to evolve the "fool-proof" machine. This idea has, apparently, also occurred to Herr Igo Etrich, who has recently revived his old love the "Taube" but has incorporated in its design such improvements as modern knowledge may suggest.
   The new Etrich "Taube" has its upturned wing tip flaps less pronounced both in size and twist, and the boom bracing of the old type has given way to a single strut on each side. The fuselage is deep and encloses a conduite interieure cabin with seating accommodation for two, the pilot in front. The fan-shaped tail of the old "Taube" has to some extent been retained, but the fixed vertical fin is a large single surface, and the rudder is wholly above the tailplane. In the old type the fin and rudder were usually divided into upper and lower above and below the tail.
   The general lay-out of the new Etrich "Taube" is fairly well shown in the photographs. The engine is a 40 h.p. Salmson, and the machine has a length of 6 m. (19 ft. 8 in.), a wing span of 11 m. (36 ft. 1 in.), and a wing area of 15 sq. m. (162 sq. ft.). The weight is about 300 kg. (660 lb.).
   The new Etrich "Taube" was built in a very small experimental workshop which Herr Etrich still maintains (his real business is textile manufacture in Czechoslovakia), and largely constructed by non-specialised labour under Herr Etrich's personal supervision. The preliminary test flights were made from a field in the vicinity of Trautenau, and there was no opportunity for accurate performance tests. The top speed, however, appeared to be in the neighbourhood of 150 km./h. (93 m.p.h.) and the landing speed about 50 km./h. (31 m.p.h.). The pilot reported the machine to be very stable, and particularly so on turns, when the lateral control did not need to be used. The take-off and climb were also described as very good indeed.