Dubat (Somali soldier) of Italian colonial troops. DVX

Dubat

The lone prototype of SAI Ambrosini SS.4 fighter aircraft at Castiglion del Lago Airfield, Lake Trasimeno, near Perugia, Central Italy, March 1939. The SS.4, designed by Sergio Stefanutti and built by SAI-Ambrosini in the Passignano sul Trasimeno’s factory, near the airfield, was the peak of experiences of the same Stefanutti over the airplanes canard formula. The canard’s concept was tested by Stefanutti with the motor-glider SS.2 and the light plane SS.3. The SS.4 was designed as single-seat, single-engine all metal fighter with retractable tricycle landing gear, arrow wing with 20 degree angle and elevons, double fin, an Isotta Fraschini Asso XI RC40 960 HP-in line engine with pusher three-blades in flight variable pitch propeller, estimated maximum speed 540 km/h, estimated minimum speed 120 km/h, armament proposed two 20 mm Mauser cannon and one 30 mm on the nose. The prototype (military registration MM387) was completed on February 1939 and transferred to Castiglion del Lago Airfield for the flight tests. But the life of SS.4 was extremely brief with a tragic end. The test pilot, Ambrogio Colombo, flew the plane for the first time at Castiglion del Lago on 7 March 19439. The day after, 8 March, prior of aircraft’s transfer by rail to Aviano, in North-East Italy, for the tests continuation, Colombo took off from another flight. But after 45 minutes of flight, 2 kilometers from the airfield, one of elevons detached and the pilot attempted an emergency landing in the campaign. During the touch down, the plane impacted with a tree. The impact caused the detachment of engine which was threw forward against the cockpit killing the pilot. According to the enquiry the accident was caused not by the SS.4’s design, but by an assembly’s fault of the elevon increased by the excessive vibrations transmitted by the engine to the airframe. Victor Sierra