In 1939 Stampe built two additional biplanes to be entered in a bidding competition for the Belgian Air Force, as they required a new training aircraft.
Stampe & Vertongen won the competition and the Belgian government ordered 300 SV.4 aircraft that same year. Production was stepped up accordingly and the manufacturing site at Antwerp was no longer large enough to cover demand.
When WWII began on September 1st, 1939 and France and England declared war against Germany, the French Armée de l’Air didn’t waste a moment. On September 9th, it placed a maximum priority order for 300 SV.4B aircraft, offering the immense sum of 129,000 Belgian francs per machine.
As Belgium was a neutral country at that time, a Belgian company could under no circumstances produce aircraft for France as a warring country. Thus Jean Stampe decided to grant a production license to France. This is how France’s Farman Aircraft Company came to produce the SV.4B.
Henri Farman Aéroplanes was an aviation business on the Camp de Chalons near Bouy on the Marne, founded and run by the French brothers Henri and Maurice Farman (Henri Farman, who died July 17th, 1958, was a pilot and aircraft mechanic; Maurice Alain Farman, 1877-1964, had already modified the G.Voisin biplane together with his brother before WWI). Together, they designed and built aircraft from 1908 to 1939. During WWII, the aviation industry was nationalized. Thus, the Farman company’s assets were allotted to the Société Nationale de Constructions Aéronautiques du Centre (SNCAC).
Thus the Stampe biplane was now also licensed for production in France. The French government ordered a further 300 SV.4 aircraft. All the aircraft produced for the French army were fitted with Renault Series 4 PEI engines.
As early as the 1940s, spectacular aerobatic performances were carried out with the Stampe. Notable were the extreme upside-down maneuvers by chief pilot Capitaine Perrier of the famous Patrouille d’Etampes.
The British aerobatic pilot Brian Lecomber, who included a Stampe SV.4B in his line-up of machines, was a devotee of the aeroplane and recommended it as an excellent teacher: "It shows up one's tiny errors in gentle slow motion, is usually fairly forgiving about things when you make a monumental faux pas - and when you do it right, performs with the most satisfying classical grace."
He described the elevator as light and sweet, an the rudder as "powerful, but definitley on the heavy side". The ailerons, otherwise effective and efficient, are, however, let down by their system of interconnection which transmits stick inputs by relay from the lower to the upper set and consequently inhibits a crisp roll entry: "half the ailerons are getting the message by second-class post" (from: Flight Fantastic, The Illustrated History of Aerobatics by Anette Carson, England, USA, 1986, page 151)
Thirty SV.4 had just been manufactured in Antwerp when on May 10th, 1940, the German Forces occupied Belgium. After just a few days, the Germans had reached Antwerp and Stampe started evacuating his factory. He transported the materials from Antwerp to Le Havre by boat and brought them to the Farman company on the Marne. More than 10 SV.4s in advanced stages of production were loaded onto trucks and moved. What couldn’t be moved had to be destroyed. The evacuation was fast and chaotic.
Jean Stampe himself travelled by ship over Ostend to Le Havre, from where he reached his old friend Farman. Stampe spent the rest of the war underground in Paris. There he passed the time by designing new aircraft types.
In 1941 two Belgian Air Force pilots crossed the English Channel with a SV.4.
In 1944 the Stampe & Vertongen Manufacturing site in Antwerp was destroyed by the German Luftwaffe.
Photo top: Jean Stampe in 1939 with a de Havilland D.H.60X Moth
Photo middle: Capitaine Perrier with his Stampe SV.4A two meters above the ground as chief pilot of the Patrouille d’Etampes in Villacoublay, 1939
Photo bottom: destroyed Stampe & Vertongen factory