Flight, July 1924

THE DESCAMPS-BRUNET A.2 SESQUIPLAN

   WE are able to give this week, through the courtesy of our French contemporary Les Ailes, a brief description of a new French machine. The Descamps-Brunet A.2 is a military two-seater reconnaissance "sesquiplan," designed by M.Brunet, a young French engineer, who has embodied in his design several interesting features. This machine is constructed entirely of metal, except for the covering of the wings, where fabric is employed. What is often held as a disadvantage of metal construction is the difficulty of effecting repairs. The method of construction adopted in the Descamps-Brunet, however, enables repairs and replacements to be effected with the same facility as that obtained with the orthodox wood construction.
   Special attention has been given as regards making the machine a production job. All the parts and fittings are rapidly detachable, while the absence of bracing wires and cables, and the employment of rigid struts in their place, not only enables the machine to be rigged very easily and quickly, but once this is accomplished it is practically impossible for the machine to get out of adjustment.
   The principal characteristics of the Descamps-Brunet A.2 are :-
   Span 14-500 m. (47 ft. 6 ins.).
   Overall length 9-350 m. (30 ft. 9 ins).
   Height 3-350 m. (11 ft.).
   Wing area 44 sq. m. (473-4 sq. ft.).
   Weight empty 1.100 kgs. (2,425-5 lbs.).
   Useful load (inc. fuel) 800 kgs. (1,764 lbs.).
   Total weight 1,900 kgs. (4,189-5 lbs.).
   Power loading 4-750 kgs./h.p. (8 lbs./h.p.).
   Surface loading 43 kgs./sq.m. (8-8 lbs./sq. ft.).
   Speed (max.) 240 km.p.h. (148-8 m.p.h.).
   Ceiling 7,800 m. (25,584 ft.).
   At present this machine is undergoing trials at Villacoublay and the results obtained so far have been entirely satisfactory.
   As previously stated, the Descamps-Brunet is a sesquiplan in which the top plane, mounted a short distance above the fuselage, has an area of 34 sq. m. (365.8 sq. ft.) while the lower plane, mounted on the bottom of the fuselage, is in comparison very small, having an area of only 9.5 sq. m. (102 sq. ft.). The top plane is set at a slight dihedral angle (1° 30) and is swept back 2°, whilst the lower plane, which is staggered forward, is straight. A single vertical panel supports the centre of the top plane on the top of the fuselage.
   A comparatively thick wing section, designed by M. Brunet, is employed. In the laboratory this section has given results equal to those of the Gottingen 430, with, however, a smaller travel of the centre of pressure.
   The wings are constructed of two main spars of I section, built up of sheet duralumin without the use of rivets. The ribs are triangulated and are built up of V-section elements secured at the joints by a single rivet. The whole of the wing frame is so constructed that repairs or replacements are easily made to individual members. Internal bracing is by tubes, giving an exceptionally rigid structure. External bracing is effected by means of four pairs of N struts, two pairs extending from the top longerons of the fuselage down to the lower plane at a point coinciding with the location of the landing wheels, the other pairs extending upwards and outwards from this point to the top plane. They are fixed to the wings by knuckle joints which allow of rapid attachment or detachment.
   Non-balanced ailerons are mounted on the top plane in such a manner that the removal of the wings will not upset their adjustment. The horizontal tail plane is interesting in that while it is rigidly mounted on the fuselage, the leading edge is adjustable during flight. The divided elevators are balanced and are hinged as usual to the trailing edge of the tail plane. The unbalanced rudder is hinged to a triangular vertical fin mounted on the top of the fuselage.
   The fuselage, which is comparatively large, is constructed of duralumin tubes (longerons, cross-members and diagonals), being assembled, by means of detachable fittings, in the form of a rigid girder. As in the case of the wings, individual members are easily repaired. The weight of the fuselage is 58 kgs (128 lbs.). It is of rectangular section, tapering sharply to the rear, where it terminates in a vertical knife edge.
   The engine mounting is easily removable, enabling a rapid change of power plant - two mechanics being able to accomplish this in about an hour. It is also possible to mount in the same machine engine mountings equipped either with the 400-h.p. Lorraine Dietrich, or some other make of engine. In designing these engine bearers special attention has been given to the elimination of vibration. The engine cooling radiator is of the Vincent Andre type, mounted below the fuselage under the engine. Temperature control is effected by withdrawing more or less of the radiator within the fuselage. The 400 h.p. Lorraine-Dietrich engine is fitted as standard.
   Both pilot and passenger have an excellent range of vision. The pilot is located beneath the trailing portion of the t op plane, a section of which is cut away for the purpose of providing a view upward, while the small dimensions of the lower plane enables the pilot to obtain a good view downwards. The gunner's or observer's cockpit is located well aft of the top plane, where he has an excellent view and range of fire in all directions.
   The control is independent of the fuselage and all cables are out of the way of the pilot and observer, being; led beneath the flooring of the cockpits. The seats and controls are adjustable to suit different "sizes" of pilots or passengers.
   A wide-track landing gear is provided, consisting of two independent housings - or "plus fours"! - each mounted out on the lower planes and each containing a wheel. The wheels are also separate, and are mounted in the housings by means of Sandow shock absorbers. There is thus a clear space below the fuselage at this point for the mounting and operation of bombs. The tail-skid is pivoted in order to facilitate steering on the ground.