Stampe et Vertongen RSV.26

This article is about the military trainer aircraft of 1926. For the light touring aircraft of 1928, see Stampe et Vertongen RSV.26/100.

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]

RSV 26/140, 26/180, and 26 Lynx
RSV.26/180 amphibian
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

Design and development

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 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 Ostend.^[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 had not only obsolete technology but were already used and worn-out.^[3] Nevertheless, the contract was too valuable to refuse, 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.

Variants

RSV 26/140

variant with a 100-kW (140-hp) Minerva engine (depending on the source, either one built^[2][3] or 29 built^[1])

RSV 26/180

variant with a 130-kW (180-hp) Hispano-Suiza engine (depending on the source, any of: 16 built, ten for the air force and six for private owners;^[2] or 26 built, 20 for the air force and six for private owners;^[3] or up to 43 built, up to 38 for the air force and five for private owners.^[15]) One RSV.26/180, civil registration O-BADE, was converted to an amphibious floatplane for a time.^{[2][16][17][18]}

RSV 26/215 or RSV 26 Lynx

variant with a 160-kW (215-hp) Armstrong Siddeley Lynx (depending on the source, either one converted from the RSV.26/140 and ten converted from RSV.26/180s^[8] or ten built^[19])

Operators

 Belgium

• Belgian Air Force

Specifications (RSV 26/180)

Data from de Maeyer 1980, p.5

General characteristics

• Crew: two
• Length: 7.15 m (23 ft 5 in)
• Wingspan: 9.38 m (30 ft 9 in)
• Wing area: 26 m² (280 sq ft)
• Empty weight: 540 kg (1,190 lb)
• Gross weight: 821 kg (1,810 lb)
• Powerplant: 1 × Hispano , 134 kW (180 hp)

Performance

• Maximum speed: 182 km/h (113 mph, 98 kn)
• Service ceiling: 7,500 m (24,600 ft)

See also

Related lists

• List of Interwar military aircraft