America´s great depression was soon felt in Europe as well and production at Stampe went downhill. The maintenance contracts for the army and numerous civilians alone kept the company going.
But Stampe was a progressive thinker. He had met the Russian aircraft builder George Ivanow in Paris and had taken him on. Ivanow made the move to Duerne with a number of countrymen to work for Stampe.
Ivanow presented a first design for the SV.1, followed then, with several necessary improvements, by the SV.2. The third version, the SV.3, was built and registered in Belgium. Not satisfied with the initial SV.3 prototype, Ivanow went back to the drawing board and in 1933, presented Stampe with the design for the SV.4, a somewhat reduced version of the SV.3. This SV.4 prototype was then manufactured (registration code: OO-ANI).
On May 17th, 1933, the Stampe SV.4 took to the air for the first time. Its pilot was Jean Stampe himself, who completed the flight without a hitch.
The SV.4 was multi-use aircraft, easily maneuverable for combat and reconnaissance purposes. After the first successful flight, Stampe´s company produced 6 further SV.4 training biplanes. These were at first used only in the company´s flying school. But the machine was an unqualified success, and the Belgian Air Force ordered 20 planes that same year.
In 1935, a delegation from Latvia came to Europe looking for a new aircraft for their air force.
After having toured factories in France, England and Holland, the delegation arrived in Duerne. The Latvians were so impressed by Stampe´s product that they ordered 10 planes on the spot. The agreed upon method of payment was a bit unusual – it was in wheat.
Later, licensed production began in Riga, Latvia (Model SV.5). At that time Jean Stampe travelled to Riga often to test fly each and every machine personally.
Stampe & Vertongen Manufacturing continued to develop. New aircraft designs were created by Ivanow. Stampe’s son worked as a test pilot for the company.
A new aircraft, the SV.10 completed its initial flight on October 4th, 1935. Stampe’s son Leon was the pilot and Ivanow came along as a passenger. The next day the two men undertook a second flight. At low altitude the plane suddenly crashed, killing both immediately.
The death of these two key persons in his life was a heavy blow for Stampe. Later one of Ivanow’s colleagues, an aircraft engineer named Demidoff, took over as chief engineer.
At first Demidoff modified the upper wings of the SV.4. Then the lower wings were redesigned as well. The new plane was given the name SV.4B.
Photo above: Jean Stampe 1933
Photo left: Stampe SV.4B