J.Davilla Italian Aviation in the First World War. Vol.2: Aircraft A-H (A Centennial Perspective on Great War Airplanes 74)

Breguet HU 3

  Two HU 3 floatplanes, were obtained by Italy before the war.

Technical

  Biplane floatplane with crew of two seated in tandem; however. The engine was a 135-hp Canton-Unne (Salmson) fixed engine.
  Wings - two bay biplane with the upper wing longer than the lower wing. Th upper wing had a 1.80 m overhang. The wings have a rectangular configuration, with a rounded tips and a thick profile. This shape was used in other, earlier Breguet designs as it had been tested in the Eiffel wind tunnel.
  The wing structure had a metal central spar and four other wooden spars, aft of the leading edge. The main ribs protruded somewhat beyond the trailing edge, and their ends were connected with metal wire. The ribs were spaced at approximately 0.12 m intervals.
  To strengthen the wing, numerous rigging wires were used from the bow of the float connecting the struts. Other wires passed from the struts to the tail of the fuselage.
  Fuselage - The fuselage had four longerons of steel stiffened with metal posts and crossbeams. They main fuselage was canvas covered, but the forward part with the engine was covered by aluminum aluminum sheets to reduce air resistance. The radiators were composed of bundles of thin tubes attached to the sides of the fuselage.
  Floats - The shape of the Breguet central float was characteristic for that firm. It had chines on the sides because the frames - straight and vertical - met at the surface of the bottom along two edges that end up on the bow.
  The dimensions are as follows: Length 4.80 m; width 1.50 m; height 0.55 m; volume 2,700 cubic meters
  The volume of 2,700 cubic meters allowed for a displacement which could support a machine twice as heavy. The central float was divided into multiple watertight compartments by longitudinal and transverse bulkheads. Its structure, however, was remarkably light.
  Tail Unit - The tail had oblique horizontal stabilizers and ended in a small step with a vertical wall. This structure was intended to strengthen the airframe and avoid vibrations or testing when exposed to wind eddies.
  The connection of the float to the device is ensured by means of uprights, two under the forward area attached to the fuselage, just behind the engine, and two others to the center of airframe (probably at or near the center of gravity). The points of attachment to the float were hinged, so that the hull could undergo slight rotations and the stern strut supports were elastic. The special system of these struts consists included a pair of oil-pneumatic shock absorbers, placed almost under the center of gravity, to dampen shocks due to ditching or waves.
  Along the upper edge of the float, in the forward section, a metal sheet was fitted to protect the propeller from splashing water.
  The outer floats, necessary for transversal stability in water, were fitted under the intermediate uprights. These floats were 1.90 m in length, 0.70 m wide, and had a volume of about a quarter of a cubic meter. They were supported with a single post plus several wires, one of which, the front, attached to the upper end of the post. The threads were elastic to allow the float a limited amount. The two stabilizing floats were also connected by means of tubes to the central float.
  The tail float had an unusual shape, with a “V” shaped part starting from the keel, while the upper part was almost flat. It was supported by four struts and various wires at the tail of the fuselage. While sitting on the water both the central and tail float would be immersed at 9 °.
  Flight Controls - The entire rudder and tail form a single, cruciform configuration connected to the end of the fuselage with a universal joint, so that the movements of the assembly were free when one or the other of the rudders was operated.
  The rudder had a span of 4.00 m and width of 1.45 m. The surface area was 4.60 sq m.The directional rudder was symmetrical. The vertical, triangular tail, which starts from the passenger seat had a surface area of 0.70 sq m.
  Both rudders were balanced, and were held in the medium equilibrium position by means of spring ties.
  The steering wheel controlled the horizontal rudder with the usual forward and backward movements of the lever, or the vertical rudder by means of its rotation.
  Lateral control was via the aileron system.

Operational Service

  The speed of the HU 3 was modest due to its somewhat high drag, ungainly layout, plus an engine of modest power.
  The Breguet seaplanes were usually equipped with wireless telegraphy (transmitting apparatus).
  During the war in Libya, eight civilian and eight military pilots were sent to Tobruk and Derna. The Flottiglia Volontari di Piloti (Civil Volunteer Civil Aviatos Fleet) reached Denza (Derna) on 25 November and Tobruk on the 28th. They were then divided into the 3a and 4a Plotone di aviazione autonoma (Autonomous Aviation Platoons). The civilians were provided with one Regia Marina Breguet HU 3 floatplane and a Deperdussin (listed as a “Concours Militaire 1911”) with a 100-hp Clerget engine.
  The HU 3s were embarked on the Dante Alighieri in 1913 and 1914. The aircraft were carried on top of Current number 2 and had to be taken in and out of the water using a ship’s crane.
  One was out of service at the end of 1915; it is uncertain as to when the second Breguet was SOC.


Breguet HU 3 two-seat floatplane with a Canton Unne engine
  Wingspan 15.40 m; length 10.20 m; height 3.50 m; wing surface area 47 sq m
  Empty weight 900 kg; payload 250 kg; loaded weight 1,150 kg
  Maximum speed 90 km/h; range 250 km
  Two acquired by the Regia Marina

L.Opdyke French Aeroplanes Before the Great War (Schiffer)