| RSV 26/140, 26/180, and 26 Lynx | |
|---|---|
| Role | military trainer aircraft |
| National origin | Belgium |
| Manufacturer | Stampe et Vertongen |
| Designer | Alfred Renard |
| First flight | 1926[1] |
| Primary user | Belgian Air Force[1] |
| Number built | between 17[2] and 98[1] |
| Developed from | Stampe et Vertongen RSV.32[3] |
The Stampe et Vertongen RSV.26/140, RSV.26/180, and RSV.26 Lynx were a family of training biplanes designed by Alfred Renard and built by Stampe et Vertongen in Belgium in the 1920s.[1] They were produced as a response to a requirement by the Belgian Air Force,[3] which became their biggest user, although private owners also bought a small number.[1][2][3]
The air force requirement was for a two-seat aircraft with aerobatic capabilities that could provide a next stage for students who had completed basic training on the RSV.32.[3] Stampe et Vertongen contracted Alfred Renard to provide a design, and for the sake of expediency, suggested that he submit a revision of his RSV.32 rather than create an entirely new aircraft.[3] The resulting RSV.26 was, like its predecessor, a conventional single-bay biplane with unstaggered wings of equal span.[4] However, the fuselage was reinforced to accommodate engines of up to 150 kW (200 hp),[3] the undercarriage legs were fitted with thicker bungee cords,[3] and the pilot's and instructor's seats were now placed in two separate cockpits in tandem.[1] The RSV.26 had wings of smaller span and area than the RSV.32, that were, despite appearances, a complete redesign of the older wing.[3] The shorter span allowed for the use of a more powerful engine and provided greater speed and maneuverability while not adversely affecting rate of climb.[3] Power was provided by a 100-kW (140-hp) Minerva engine in the nose, driving a two-bladed propeller.[3] The prototype made its public début on 26 June 1926 at a rally at Ostende.[3][5]
The air force evaluated the type and judged it suitable.[3] However, the new Minerva engines cost 50,000 BEF while the government could purchase war-surplus Hispano-Suiza engines from France for only 6,500 BEF.[3] Consequently, Stampe et Vertongen was asked to adapt the design to the alternative powerplant.[3] The firm was reluctant to accommodate the change, as the Hispano-Suiza engines and cooling systems were heavier than their Minerva counterparts, and were not only obsolete technology but were already used and worn-out.[3] Nevertheless, the contract was too valuable to turn down, and Renard altered the design accordingly.[6] The biggest change was to move the upper wing forward, staggering it with the lower wing to preserve the aircraft's centre of gravity.[7] The change also provided improved access to and visibility from the forward cockpit.[6] The air force purchased the RSV.26 in this form, now designated RSV.26/180 to reflect its more powerful engine.[2][6] In service, it was known as the RSV décalé[2] or 26 décalé[6] ("staggered" in French).
The start of the RSV.26/180's career was troubled by a handling problem that made three-point landings almost impossible.[6] The cause was traced back to the factory: an error in making the templates for the wing ribs resulted in all the wings having the wrong profile.[6] Stampe et Vertongen rectified this at the firm's own expense.[6] Other problems with the type were due to the second-hand engines, which suffered continual mechanical breakdowns[7] and by the early 1930s had contributed to a long list of accidents.[8] To investigate a solution to the ongoing situation, the air force returned the RSV.26/140 prototype to the factory to be fitted with an Armstrong Siddeley Lynx engine.[9] When the resulting modification proved successful, the air force had ten of its RSV.26/180s re-engined the same way.[8] With the new engines fitted, they were redesignated RSV.26/215[1] or RSV.26 Lynx.[8][10][11] Following their military careers, ten RSV.26/180s were sold to private owners in 1936.[12][13]
Histories of Stampe et Vertongen differ on the number of RSV.26/140s and RSV.26/180s produced, with figures as disparate as 17[2] and 98[14] published.
Data from de Maeyer 1980, p.5
General characteristics
Performance
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