Flight, September 1922
The Darmstadt Machines. - Of the various "groups" that competed at Rhon the Hannover students did best of all, owing to the remarkable flights made by Martens and Hentzen on the "Vampyr." So much was this the case that nearly all the first prizes were won by
representatives of the Hannover High School. Other institutions, however, also collected respectable prizes, notably the Darmstadt "group" (Akademischer Fliegergruppe, Hochschule, Darmstadt), whose students had entered three machines for the competition. By the courtesy of Flugsport we are able to publish, in addition to our own photographs, general arrangement drawings of the three Darmstadt machines, two of which are monoplanes and one a biplane.
Of the three Darmstadt machines the one which appears to have done best is No. 4 ("Edith" ) , which was piloted by Bottsch. This machine, which is shown both in photographs and scale drawings, is a parasol monoplane, in general arrangement not unlike the Hannover "Vampyr"; that is to say, it has a ply-wood covered fuselage with a monoplane wing placed above. The wing construction is, however, somewhat different from that of the Hannover machine, notably on account of the employment of two wing spars. The "Edith" is not a true cantilever machine, as two struts on each side slope outwards for a considerable distance from the lower longerons of the body. The monoplane wing is straight and non-tapered both in chord and thickness, and is built up of two halves joined on the centre line of the fuselage. As in the Hannover, the entire leading edge is covered with three-ply wood to give extra stiffness and to retain the shape. The fuselage is rectangular section with a triangular portion added behind the pilot's seat. The undercarriage is in the form of two skids (flexible) of ash. The weight of the machine empty is stated to be 200 lbs., so that assuming a weight of 160 lbs. for the pilot, the total loaded weight is 360 lbs. and the wing loading 360/172 = 2.1 lbs./sq. ft., which is fairly high for a glider. Nevertheless, Bottsch on this machine was awarded third prize in the competition for slowest rate of descent. The Darmstadt monoplane No. 6 ("Geheimrat") was piloted by Hackmack, and received second prize in the slow rate of descent competition. Generally speaking, the "Geheimrat" is not greatly different from "Edith," but its monoplane wing, is divided into three separate portions, a large centre section and two tapered end pieces. The wing is so mounted that the angle of incidence can be adjusted during flight. The weight of the machine is the same as that of the "Edith" (200 lbs.), as is also the wing loading. The wing is carried on two vertical extensions of the sides of the fuselage, and no external bracing struts are employed.
The third Darmstadt machine is a small biplane with a short enclosed nacelle and open tail booms. To a certain extent the machine is reminiscent of the early Caudron biplanes, except that the skids on which it lands are not continuations of the lower tail booms, but are a separate structure. The biplane wings show the usual wire bracing, but lateral control is by wing warping. One of our photographs shows the construction of the nacelle. As in the monoplane, three-ply wood is extensively used.
In our introductory remarks it was pointed out that the cantilever monoplane is necessarily somewhat heavier than a biplane structure. The wing area of the Darmstadt biplane is 150 sq. ft., and the weight empty is 110 lbs., so that with pilot on board the wing loading of the biplane is approximately 1-8 lbs./sq. ft., in spite of the fact that the area is some 22 sq. ft. smaller than that of the monoplanes. On the other hand, the monoplanes probably have a considerably higher maximum lift coefficient.
THE DARMSTADT MONOPLANE GLIDER "EDITH." In the illustration the machine is just getting away. Note the tow rope dropping from its quick-release in the nose of the fuselage.
The Darmstadt monoplane, piloted by Bottsch, flying over the Dresden biplane.
The Darmstadt monoplane, of which scale drawings were published in our issue of September 21, 1921. Herr Bottsch just managed to land the machine before striking the trees, but damaged the fuselage in doing so.
Herr Bottsch in the cockpit of the Darmstadt machine. Note the quick-release in the nose of the fuselage. This machine has made flights of long duration, one being of 1 1/2 hours.
Two-seater Gliders: Front portion of the "Margarete" (No. 35), showing two cockpits and peculiar mounting of the monoplane wing.
THE MARGARETE: A glider of the intermediate type being flown by the flying section of the Technical High School at Darmstadt. They gained the first prize for the two-seater class in the Rhon Gliding Competition.
A two-seater glider at Rossitten: The Academic Flying Group, Darmstadt's "Margarete," in flight over the Kurischen-Haff. Note the kind of country over which the machines fly.
From the Rhon Meeting: No. 46 ("Moritz") and No. 35 ("Margarete") in the air together. On this occasion "Margarete" is not carrying a passenger.
TWO DARMSTADT FUSELAGES: Top, the body of the Type 4 monoplane; bottom, the nacelle of the biplane.
THE THREE DARMSTADT MACHINES: General arrangement drawings.