Stampe SV-4A

The SV-4A designation appears in the sources with two different meanings, and both deserve telling because they are often merged into one.

The first concerns the Belgian pre-war aircraft. According to aviationsmilitaires.net, in 1937 Elsa Leysen, a former pupil of the Stampe et Vertongen flying school, was looking for an aerobatic aircraft better than the de Havilland DH-82 and the Bücker Jungmann. The firm's technical team reworked its S-IV of 1933: it shortened the fuselage, changed the tail, swept the upper wing, reduced the span by rounding the wingtips and fitted ailerons to the lower wing. The modified prototype was named SV-4, and the aerobatic version derived from it, like the training version, was designated SV-4a, with a Renault 4P05 four-cylinder inverted in-line engine of 140 hp (104 kW). The English Wikipedia follows the same line and calls the SV.4A the first model, an advanced aerobatic trainer with the Renault 4P-O5. In that account the firm built two more aircraft in 1939 for the Belgian military's trainer competition; the SV-4a was selected and 300 were ordered, and the French Armée de l'Air, won over by its performance, ordered 600. When the war began only about twenty Belgian SV.4a had been completed and eleven were being assembled, and only one came through whole; the same site lists a single SV-4a in the RAF, after a Belgian pilot crossed the Channel with it in 1941.

That pre-war reading is disputed. The French Wikipedia article devoted to the SV-4b, the Dutch Wikipedia and the FRROM documentation attribute the 1939 competition win, the Belgian order and the 1941 escape aircraft to the Gipsy Major-engined SV-4B, not to a Renault-engined SV-4A; the Dutch Wikipedia also says the two 1937 machines were built for Mrs Leysen and for Thierry d'Huart. Those figures belong to the SV-4B and are not repeated here: what can be stated for the SV-4A is that the sources do not agree on whether a Renault-engined SV-4A existed as a Belgian production type before the war.

The second meaning is French and post-war, and it is the better documented. After the war the Armée de l'Air ordered 700 Stampes from SNCAN's Sartrouville factory, according to the Musée Européen d'Aviation de Chasse at Montélimar (MEAC); the French Wikipedia gives 701 aircraft built by SNCAN, numbered 1 to 701. Those aircraft were SV-4Cs with the Renault 4P. According to the MEAC, from construction number 560 the SV.4C took the name SV4A, the A standing for acrobatique, and its Renault 4PEI (01-03) was replaced by a 4PO5 fed for inverted flight. The FRROM documentation, which cites Réginald Jouhaud's books on the Stampe, puts it another way: 50 Armée de l'Air Stampes used a Renault 4-PO5 that allowed sustained inverted flight and so permitted aerobatics, and that version was designated S.V.4a. Externally, the same documentation tells the A from the C by humps on the engine cowling, which the C lacks.

One documented example is F-BDNM, an S.V.4a with construction number 668 flown at Saint-Yan with the black number 9; it was one of the first ten Stampes delivered to Saint-Yan, on 10 April 1948. Avionslegendaires.net likewise describes the SV.4A as a model licence-built by SNCAN and powered by a Renault 4-PO5, which it rates at 145 hp where the other sources give 140 hp, and lists for it a span of 8.40 m, a length of 6.90 m, a height of 2.77 m, a loaded weight of 780 kg, a top speed of 200 km/h, a 5000 m ceiling and a 600 km range. The French Wikipedia and aviationsmilitaires.net sum the version up in the same terms: an aerobatic aircraft with the 140 hp Renault 4PO5, rounded wingtips and ailerons on both wings.

Survivors still carry the designation. The Wikipedia articles illustrate it with the Belgian-registered SV-4A OO-GWC and with a Nord-built SV4A, serial 219, in New Zealand; that serial is lower than the 560 threshold quoted by the MEAC, and the sources consulted do not explain the difference. Aviationsmilitaires.net adds that the unofficial SV-4e designation covers SV-4a or SV-4b aircraft re-engined with a 180 hp (134 kW) Lycoming O-320. No source in hand gives a reliable total of SV-4As or a first-flight date for the version.