Flight, February 1924
THE "FEIRO I" COMMERCIAL MONOPLANE
First Hungarian Machine has a Rotary Engine
A NEW commercial monoplane, the first to be designed and built in Hungary, has recently been completed at the Budapest works of the firm of Feigl and Rotter.
The machine was designed by Herr Ladislas Rotter, and is shown in the accompanying illustrations. It will be observed that the machine is fitted with a 120 h.p. Le Rhone engine. This engine was installed in the first experimental machine, as it happened to be available, but we understand that in subsequent machines either Haacke or Siemens radial engines will be fitted, although any engine developing between 100 and 140 h.p. can be fitted.
The "Feiro I" is a strut-braced monoplane, with the wing resting on top of the fuselage. A very high factor of safety has been adopted, no less than 12, a figure that appears unnecessarily high for a machine of this type. Constructionally the machine is of interest mainly because of the extensive use of three-ply wood. The entire fuselage, with the exception of the nose, and the wing are covered with this material, the wing being built without internal drag bracing.
The monoplane wing is built in two halves and braced to the lower longerons by two struts on each side. The wing spars are of box section with spruce flanges and three-ply webs. The ribs are also mainly of three-ply, and to them is nailed the three-ply wing planking. The wing can be dismantled by undoing eight bolts. The section used is one of the Joukowsky-Gottingen "tadpole" sections, having a maximum life coefficient of 0-8 "absolute." Thus, in spite of the high wing loading, the landing speed is stated not to be unduly high.
The fuselage, as already mentioned, is a three-ply covered structure of rectangular section, capped by a turtle-back fairing. The front portion of the fuselage is, however, a steel tube structure, and is covered with sheet aluminium up to the front of the cabin. The latter has seating accommodation for four occupants, or rather two side by side in the rear (enclosed) part, and two side by side (pilot and passenger) in the forward part, which is partly open, owing to the cockpit opening being cut very low on the sides. This has been rendered possible by making the deck fairing very deep in proportion to the depth of the main fuselage structure. It would not appear that the pilot's view forward can be particularly good, as the deck fairing in front of him is fairly wide.
Access to the cabin, as well as to the pilot's cockpit, is by a door in the side, and in addition the cabin is well lighted by large windows, which can all be opened for ventilation. As the cabin width is close on 4 ft., there is ample room for the occupants to sit side by side. Dual controls are provided in the pilot's cockpit, one of the sets being easily removable. A trimming tail plane is fitted so as to allow of flying with full or part load. The fin and tail plane are covered with ply-wood, while the rudder and elevator are fabric-covered.
The undercarriage is of the "vee" type, braced laterally by "vee" struts in place of the more usual wire bracing. The engine housing is separated from the cockpit by two fireproof bulkheads placed some little distance apart. Between these bulkheads is placed the carburettor, the space between the bulkheads being ventilated by the air blowing past the openings in the sides. The petrol tank is mounted in the centre of the wing, above the cabin, and direct gravity feed from the main tank to the engine is provided.
The main characteristics of the ''Feiro I” are as follows: Length over all, 8-83 m. (28 ft. 11 ins.); span, 14-25 m. (46 ft. 9 ins.); chord, 2 m. (6 ft. 7 ins.); wing area, 26 sq. m. (280 sq. ft.); area of tail plane, 3 sq. m. (32-3 sq. ft.); area of elevators, 1-8 sq. m. (19-4 sq. ft.); area of fin, 0-36 sq. m. (3-9 sq. ft.); area of rudder, 0-7 sq. m. (7-5 sq. ft.). The weight empty is 750 kgs. (1,650 lbs.), and the useful load 450 kgs. (990 lbs.), giving a total loaded weight of 1,200 kgs. (2,640 lbs.). The wing loading is, therefore, 9-43 lbs./sq. ft., and the power loading, assuming 120 h.p., 22 lbs./h.p. Speed tests over a measured course have not yet been carried out, but the estimated maximum speed of the machine is 160 kms. (100 m.p.h.). It is stated that the machine takes off after a run of approximately 50 yds., and that it climbs and handles well. Further tests are now being carried out.