avia.wikisort.org - Aeroplane

The Sikorsky S-9 Kruglyj (Rounded One) was a Russian single engine prototype aircraft completed in the spring of 1913 by the Russian Baltic Railroad Car Works while Igor Sikorsky was the chief engineer of the aircraft manufacturing division.

S-9
Sikorsky S-9 circa 1913
Role	Experimental Monoplane Type of aircraft
National origin	Russian Empire
Manufacturer	Russian Baltic Railroad Car Works
Designer	Igor Sikorsky
First flight	1913
Number built	1

Design and development

The S-9 was a three-seat mid-wing monoplane with constant-chord wire-braced wings originally powered by a Gnome air-cooled rotary engine rated at 100 hp (75 kW). It was the first monocoque monoplane built in Russia and the cylindrical tapered fuselage was constructed of plywood 5 mm thick in the forward section and 3mm thick aft. Construction was completed in the spring of 1913.[1][2]

Operational history

Upon completion the S-9 was found to be substantially heavier than anticipated and the engine only delivered 80% of its rated horsepower. Initial flight tests revealed very poor performance. The engine was replaced by a 100 hp (75 kW) Gnome Monosoupape and further flights showed only a nominal increase in speed. The machine was eventually scrapped.[1]

Specifications

Data from Russian Aviation Museum[2]

General characteristics

• Crew: One
• Capacity: Two passenger
• Upper wingspan: 39 ft 4 in (12 m)
• Wing area: 320 sq ft (30 m²)
• Empty weight: 1,521 lb (690 kg)
• Gross weight: 2,183 lb (990 kg)
• Powerplant: 1 × Gnome Monosoupape 7-cylinder air-cooled rotary piston engine, 100 hp (75 kW)
• Propellers: 2-bladed

Performance

• Maximum speed: 56 mph (90 km/h, 49 kn)
• Wing loading: 6.8 lb/sq ft (33 kg/m²) max load

References

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