Letov Š-31
| Letov Š-31/131/231/331/431 | |
|---|---|
 Letov Š-31 |
|
| Type: | Fighter plane |
| Design country: | |
| Manufacturer: | |
| First flight: |
1929 (Š-31) |
| Number of pieces: |
К-31: 33 |
The Letov Š-31 aircraft is a single-engine, single-seat biplane that was developed as a fighter aircraft . The first flight of the machine took place in 1929. The type was manufactured in the Letov factory in Letňany near Prague in Czechoslovakia. The construction was carried out by Alois Šmolík . The landing gear was rigid and had a tail skid . The machine was made entirely of metal. The wings were braced and braced with an N-stem on both sides. They were also attached in the area of the fuselage with two N-posts. The engine powered a two-bladed wooden propeller , also made by Letov. Variants of the machines were used in the Spanish Civil War until 1938.
Letov Š-31
The machine is based on the Letov Š-20 , but had a more powerful radial engine . 33 pieces were ordered. However, they were soon ousted from their role as fighter aircraft and then used as advanced training aircraft.
Letov Š-131
This machine essentially corresponded to the Š-31, but had a more powerful engine (BMW Hornet) and, in particular, showed greatly improved climbing performance. To climb to 5000 meters, the machine only needed 6.5 minutes (instead of 10 minutes as in the initial sample). The pattern was specially designed for use in air races. Only three machines of this type were made.
Letov Š-231
In this variant, the aerodynamics have been significantly improved. The machines received a modified wing profile and the radial engine was provided with a Townend ring . The Bristol Mercury was chosen as the engine . The first flight of this variant - originally called Letov Š-31A - took place on March 17, 1933. Some changes were made to the structure and test flights continued. On July 21 of the same year the machine was handed over to the Military Air Technology Institute. Shortly after this handover, the Š-231 broke apart during the dive test, whereby the test pilot was killed. It was found that the aircraft fuselage was not able to withstand the loads actually occurring, although previous load tests had turned out to be satisfactory. However, after detailed negotiations between the Ministry of Defense and the Letov plant, a second prototype was ordered and serial production of 23 Š-231s began.
After further thorough tests in 1934, official approval for series production was granted on November 3, 1934 . The price for a series machine was 264,000 crowns. The guy was transferred to the troop service in 1934, but was only able to hold out for barely two years. As early as 1936, seven machines in the Letov factory were dismantled and packed in boxes and sent to Spain to be used by the Republicans in the Spanish Civil War . Due to the lack of technical documentation, however, there were difficulties in assembly and use. Four were destroyed in startup accidents. The other three, however, were used for combat missions. In 1937 another ten machines were brought to Spain. Based on the experiences already made with the first delivery, these proved themselves well.
Overall, it was found that the biplane fighter aircraft were already out of date compared to machines like the Polikarpow I-16 or the even more modern Messerschmitt Bf 109 and Hawker Hurricane .
Letov Š-331
Version with an even stronger engine. The only copy was sold to the Republicans fighting there during the Spanish Civil War. The first flight took place in 1935. In the same year, Jiři Anderle set an altitude record of 10,651 meters.
Letov Š-431
Prototype with a 14-cylinder double radial engine Armstrong Siddeley Tiger. The machine crashed during testing in 1936. With this, the series of the Š-31 was finally discontinued.
Military use
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Slovakia
- Slovak Air Force
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Spain
- Spanish Republican Air Force
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Spain
- Spanish Air Force
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Czechoslovakia
- Czechoslovak Air Force
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Technical specifications
| Parameter | Š-31 | Š-131 | Š-231 | Š-331 | Š-431 |
|---|---|---|---|---|---|
| length | 7.15 m | 7.80 | 7.90 m | ||
| span | 9.80 m | 10.06 | |||
| height | 2.95 m | 3.00 m | |||
| Wing area | 21.80 m² | 21.50 m² | |||
| Wing loading | 57.4 kg / m² | 63.9 kg / m² | 82.5 kg / m² | 91 kg / m² | 84 kg / m² |
| Empty mass | 830 kg | 970 kg | 1280 kg | 1450 kg | 1310 kg |
| Takeoff mass | 1254 kg | 1392 kg | 1770 kg | 1950 kg | 1805 kg |
| Top speed | 254 km / h | 292 km / h | 348 km / h | 405 km / h | 370 km / h |
| Cruising speed | 225 km / h | 270 km / h | 310 km / h | 385 km / h | 345 km / h |
| Ascent time to 5,000 m | 10 min | 6.50 min | 8.28 min | 6.44 min | 6.58 min |
| Service ceiling | 8,000 m | 10,000 m | 9,300 m | 11,200 m | 9,500 m |
| Range | 320 km | 450 km | 410 km | 450 km | |
| Armament | 2 × MG 7.7 mm | 4 × MG Strakonice 30 7.92 mm, pneumatically operated 6 light bombs of 12 kg each |
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| drive | 1 × 9-cylinder radial engine Walter Jupiter with 331 kW (450 PS) | 1 × 9-cylinder radial engine BMW Hornet with 386 kW (525 PS) | 1 × 9-cylinder radial engine Walter (Bristol) Mercury V-S2 with 412 kW (560 PS) | 1 × 14-cylinder double radial engine Walter K-14 II with 662 kW (900 PS) | 1 × 14-cylinder double radial engine Armstrong Siddeley Tiger with 500 kW (680 PS) |
See also
literature
- Václav Němeček: Československá letadla. Naše Vojsko, Prague 1968.
Web links
- Letov Š-31 on vinar.cz (Czech)
- Letov Š-31 on airwar.cz (Russian)