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Š-20 and Š-21
	Š-20
Role	Fighter
National origin	Czechoslovakia
Manufacturer	Letov
First flight	1925
Number built	ca 118

The Letov Š-20 was a fighter aircraft produced in Czechoslovakia during the 1920s.

Design and development

The Letov Š-20 was a conventional, single-bay biplane with unstaggered wings, braced by N-struts. In overall appearance, it greatly resembled contemporary SPAD fighters. The fuselage and empennage were of welded steel tube construction and covered in fabric. The wings had a tubular metal spar but were otherwise wooden, and also fabric-covered.^[1]

The Czechoslovakian Air Force bought 105 machines, and ten examples were produced for Lithuania under the designation Š-20L. These remained in service until 1936 and 1935 respectively.

Operational history

An Š-20 placed second in the single-engine category of the national President of the Republic air race in 1925, but fared better the following year. In the 1926 race, an Š-20 not only won this category, but also set a new national airspeed record of 234 km/h (146 mph). This record was short-lived, however, since the prize for the fastest circuit was also won in an Š-20, and this raised the record to 245 km/h (153 mph).^[2]

A single prototype of an unarmed advanced trainer version was built as the Š-21, but this did not sell.

Variants

Š-20 – initial production version
- Š-20M – revised version with slimmed down rear fuselage (main production version for Czechoslovakia)
- Š-20L – export version for Lithuania (eight built)

- Š-20R – version with further revisions to fuselage (one built)
- Š-20J – version with Walter-built Bristol Jupiter engine
Š-21 – trainer version with Hispano-Suiza 8Aa engine (one built)

Specifications (Š-20)

Data from Jane's all the World's Aircraft 1928^[3]

General characteristics

Crew: 1
Length: 7.44 m (24 ft 5 in)
Wingspan: 9.6 m (31 ft 6 in)
Height: 2.56 m (8 ft 5 in)
Wing area: 18.4 m² (198 sq ft)
Empty weight: 740 kg (1,631 lb)
Gross weight: 1,050 kg (2,315 lb)
Powerplant: 1 × Škoda-built Hispano-Suiza 8Fb V-8 water-cooled piston engine, 221 kW (296 hp)
Propellers: 2-bladed wooden fixed-pitch propeller

Performance

Maximum speed: 257.5 km/h (160.0 mph, 139.0 kn)
Range: 528 km (328 mi, 285 nmi)
Endurance: 2 hours 10 minutes
Service ceiling: 7,250 m (23,790 ft)
Rate of climb: 6 m/s (1,200 ft/min)
Time to altitude: 5,000 m (16,000 ft) in 13 minutes 40 seconds
Wing loading: 57 kg/m² (12 lb/sq ft)
Power/mass: 0.2163 kW/kg (0.1316 hp/lb)

Armament

Guns: 2x fixed, forward-firing, synchronised 7.7 mm (0.303 in) Vickers machine-guns (ZB vz.09) in the forward fuselage upper decking

References

Notes

^ Taylor 1989, p. 573.
^ Taylor 1969, p. 63.
^ Grey, C.G., ed. (1928). Jane's all the World's Aircraft 1928. London: Sampson Low, Marston & company, ltd. p. 79c.