Журнал Flight

Flight, March 12, 1915.

AN AMERICAN "PARASOL" MONOPLANE - THE GRINNELL.

   IN general design, several of the latest aeroplanes built in the United States have followed, more or less closely, European practice. From this it must not be inferred that they lack originality, for the latter is to be found in constructional details, whilst in some cases traces of American practice still remain. One of these "European" models that has given very satisfactory results is the Grinnell monoplane, designed by William C. Robinson and built by the Grinnell Aeroplane Co. of Grinnell, Iowa. This machine is of the "Parasol" type, i.e. having the mounted above the body, a practice introduced little time back by the Morane-Saulnier and Bleriot firms, which has proved its worth on active service. The principal advantages of this type are an increased range of vision, and, so it has been claimed, an improvement in stability. The Grinnell parasol differs from the Morane-Saulnier and Bleriot machines of this type in that the wings are not all in one piece, but in two sections, leaving an open space in the centre above, and of about the same width as, the body. By this arrangement an unobstructed view upwards is obtained, and in this respect it is certainly an improvement, but it would be interesting to know if the space in the centre of the wings has any effect aerodynamically. The wings, which are rectangular in plan-form, are supported above the body by two pairs of short tubular struts. The front and rear pairs of these struts are each connected to a horizontal tubular member which receives the inner ends of the front and rear wing-spars respectively - forming, in fact, continuations of the spars. Four tubular extensions of the short struts form a pyramid above the wings from which the latter are braced. The rectangular body is not unlike that of the Nieuport monoplane, and in the nose is mounted the 100 h.p. engine. The latter is also of Robinson's own design, and is a 6-cyl. radial (fixed) air-cooled engine having a bore and stroke of 5 ins. and 6 ins. respectively. Behind the engine are the fuel tanks, and behind these again are the pilot's and passenger's seats, arranged side by side. The front portion of the body forward of the cockpit is covered with sheet aluminium, and the remainder with fabric. The tail consists of two almost rectangular stabilizing surfaces, mounted on either side of the rear extremity of the body, with elevator flaps hinged to the trailing edges. A peculiar feature of the stabilising surface is that the leading edge is curved forwards where the abutment against the body takes place, so that a kind of peak is formed. Pivoted to the sternpost of the body is a circular-shaped partially balanced vertical rudder
   The under-carriage is both simple and strong. It consists of two tubular steel U struts, to the lower extremities of which are sprung the two running wheels. The front under wing-bracing cables are anchored to the forward members of the U struts, whilst the rear under bracing or warp cables are carried by the lower longitudinals of the body. It was on this machine that W. C. Robinson put up the American cross-country record last October (375 miles in 4 hrs. 44 mins.). The principal dimensions of the Grinnell monoplane are :- Span 35 ft.; chord 7 ft.; supporting area 225 sq. ft.; overall length 25, ft.; weight empty 900 lbs.; speed about 80 m.p.h.