Ambrosini SS . 4 The SAI - Ambrosini SS . 4 was an Italian fighter prototype developed in the late 1930s , featuring a canard - style wing layout and a ' pusher ' propeller . Development of the SS . 4 was abandoned after the prototype crashed on its second flight . Development . Sergio Stefanutti had already experimented with canard aircraft with the S . C . A . SS . 2 and S . C . A . SS . 3 " Anitra " ( " Duck " ) , light aircraft built by " Stabilimento Costruzioni Aeronautiche " ( SCA ) at Guidonia ( a new city focussed on aviation ) . The single - seat SS . 2 had a canard wing configuration , fixed undercarriage and was powered with a 2 - cylinder Keller engine rated at . The SS . 2 first flew in 1935 , and one of the two prototypes was converted into a two - seater with a larger CNA II engine built by " Compagnia Nazionale Aeronautica " . This new aircraft first took to the air on 2 October 1937 and was officially revealed in Milan at an international air exposition and the small fixed - undercarriage SS . 2 was sent to Passignano for evaluation . Experience with this machine and the study of its aerodynamics led Stefanutti to design a canard style interceptor and air superiority fighter , designated SS . 4 , very similar in layout to the SS . 2 and SS . 3 . The SS . 3 had a span of and was long with an overall height of . With a engine it was capable of a maximum speed of and able to reach an altitude of altitude . Stalling speed was : A prototype SS . 4 was built at the " Società Aeronautica Italiana - Ambrosini " factory in Passignano sul Trasimeno , Umbria . Relatively little flying was carried out as development of the SS . 4 was abandoned after the prototype crashed , killing the test pilot . The design barely compared favourably to contemporary fighters , and the Regia Aeronautica decided not to pursue the design , despite having already ordered a second aircraft which was cancelled . Description . The SS . 4 was a single seat fighter of all - metal construction with a canard configuration wing with twin fins mounted on the wing trailing edges , retractable tricycle undercarriage and short fuselage with rear - mounted engine driving a pusher propeller . The pilot was accommodated in an enclosed cockpit in the centre of the fuselage forward of the two fuel tanks and aft of the armament in the nose . Visibility from the cockpit was excellent to the sides and front , but restricted to the rear by the large main wing , engine and large twin fins positioned at approximately the half - span position . Flying controls consisted of elevators on the trailing edges of the canard fore - plane controlling pitch , rudders on the large fins controlling yaw and ailerons on the main wings to control roll . Pitch trim was set by adjusting a trim tab on the starboard elevator . The moderately swept , tapered , high aspect ratio wings had no sweep on the trailing edge and a cut back to give clearance for the propeller , with the large fins with rudders extending past the trailing edge at the ends of the cut - backs , to ensure enough moment to give adequate control and stability . The delta fore - plane was of low aspect ratio with the elevators sited below the trailing ege similar to the method used by contemporary Junkers aircraft like the Junkers Ju 87 . The engine was a powerful liquid - cooled Isotta - Fraschini Asso XI R . C . 40 engine capable of driving a three - bladed metal propeller . The engine was cooled by two radiators either side of the fuselage in ducts just behind the cockpit . Fuel for the engine was housed in two fuel tanks located mid - fuselage along with an oil tank . Three armament options were proposed for light , general purpose and long - range versions ; the light interceptor / fighter was to have had two machine guns in the nose of the fuselage ; the general purpose fighter was expected to be armed with the fuselage guns and two wing - mounted cannon ; the long - range version would have had only the wing - mounted cannon and carry two drop tanks under the wings . Operational history . The prototype SS . 4 was built by SAI Ambrosini , Passignano sul Trasimeno , and then sent to Eleuteri airport , Castiglione del Lago , also in the Trasimeno area . There , the aircraft was successfully flown for the first time on 7 March 1939 . The next day the SS . 4 prototype was scheduled to be transported to Aviano airbase by rail , but Ambrosini ' s chief test pilot Ambrogio Colombo wanted a second test flight . After 45 minutes , an aileron malfunctioned just from Eleuteri . Colombo attempted to land but was unable to reach the runway and crashed near Campagna , hitting a tree . Colombo was killed when the engine pushed through the rear bulkhead and crushed him against the front of the cockpit . A memorial to him was erected near the site of the crash . The investigation into the crash concluded that the accident was due to imperfect construction which led to a faulty installation of the aileron which had failed . The study also pointed out the excessive vibrations transmitted by the engine to the wing .