Intended as a successor to the Spad 7 and 13 in service with the newly-created Czechoslovak Air Force, and selected in preference to the Š 3 parasol monoplane, the Š 4, initially designated S HS. 1, was a single-bay unstaggered biplane of mixed construction with fabric-covered wooden wings and metal fuselage and tail.

Flown in 1922, the Š 4 was powered by a 220 hp Hispano-Suiza 8Ba engine and carried an armament of two synchronised 7,7-mm Vickers machine guns.

A series of S-4 fighters was ordered, but 20 of these were completed with the 180 hp HS 8Aa engine as Š 4a aerobatic trainers. As a result of low manufacturing standards a number of difficulties were experienced with the S4 which was grounded in 1927, the surviving aircraft being rebuilt in 1928 to Š 4a trainer standard.

Letov Š -4 / SHS-4
Engine: 1 x 220hp Hispano-Suiza 8Ba
Max take-off weight: 980 kg / 2161 lb
Empty weight: 673 kg / 1484 lb
Wingspan: 8.00 m / 26 ft 3 in
Length: 6.58 m / 21 ft 7 in
Height: 2.62 m / 8 ft 7 1/8 in
Wing area: 16.43 sq.m / 176.85 sq ft
Max. speed: 232 km/h / 144 mph
Cruise speed: 200 km/h / 124 mph
Rate of climb: 323 m/min / 1050 ft/min
Climb to 5000m: 21 min 50 sec
Service ceiling: 5500 m
Range: 500 km / 311 miles
Armament: 2 x 7.7mm
Crew: 1

Š -4a
Engine: 180 hp HS 8Aa

The first original fighter design to be produced by the Vojenská továrna na letadla (State Aircraft Works) “Letov”. The Š 3 was created by Ing Alois Smolik who had formerly worked for the Austro-Hungarian government Initially designated as S B.1, the original prototype was destroyed in a fire at the Prague-Letnany factory on 5 November 1921, but a second prototype entered flight test early in 1922.

A single-seat parasol monoplane powered by a 185 hp BMW l1la six-cylinder in-line engine and carrying an armament of two 7,7-mm Vickers machine guns, the Š 3 was of mixed construction with a wooden wing and metal fuselage and tail. The Š 3 participated in the International Meeting in Zurich in 1922, taking third place in the precision take-off and landing contest and seventh place in the aerobatic contest. Further development was discontinued in favour of the S 4.

Š.3
Crew: 1
Engine: 1 x 185hp BMW IIIa
Max take-off weight: 928 kg / 2046 lb
Empty weight: 662 kg / 1459 lb
Wingspan: 10.13 m / 33 ft 3 in
Length: 7.08 m / 23 ft 3 in
Height: 3.04 m / 10 ft 12 in
Wing area: 17.60 sq.m / 189.44 sq ft
Max. speed: 225 km/h / 140 mph
Cruise speed: 195 km/h / 121 mph
Rate of climb: 508 m/min / 1650 ft/min
Time to 9,840 ft (3000 m): 5.9 min
Range: 472 km / 293 miles
Armament: 2 x 7.7mm

Since the first controllable heavier-than-air flights had been made, the Austria-Hungarian administration did not intend to establish aeroplane manufacturing in Bohemian or Moravian Lands. An Aeroplane Repairs Works “Al-Ma” was set up by Dr. Martius, being of German origin, in the Prague district of Holešovice in 1916. Several days after the independent state of Czechoslovakia had come into existence on October 28, 1918 the Air Force Corps was founded and an order to move all the aeroplanes and air material to Prague was issued. On November 18, 1918 nine planes were seized by the Czechs and eight of them ferried from the town of Cheb to Prague situated near border on Germany so that the Germans were prevented from flying them into Germany. This unexpected raid was commanded by Cpt. Adamec [Addammaets] who was later appointed the Aeroplane Arsenal`s CO. The ninth Czech pilot had to land in Germany and his aircraft was confiscated.

Every plane was concentrated at the Prague Fair Facility until February 1919. A young P/O Alois Smolik was in charge of repairs. He used to be as an asistant to the Air Expert and Scholar Profesor Miess. The Sm-1 biplane designed by Alois Smolik and flight-tested in Apríl 1919 persuaded the Czechoslovak government to prefer the home-production aircraft to ones imported from France, though 115 French planes were presented them.

Originally built in 1910 as the SH-1 with 127 kW (230 hp) Hiero L engines, the SH-1 was later redesignated Š-1. 28 were built.

The Letov Š-1 was a single-engined, two-seat biplane surveillance aircraft. Designed by Alois Šmolík at Letov Kbely, it was first military aircraft built in Czechoslovakia.

The Š-1 first flew in 1920.

The SM-1 variant was powered by 194 kW (260 hp) Maybach Mb.IVa engines and later redesignated Š-2. 64 were built. This 2 seater was armed with one forward firing machine gun and had a twin movable machine gun in the rear. 28 were built.

The Sm A 1 was a commercial variant with a canopy over the rear cockpit for 2 passengers.

The Letov Š-10 of 1921 was an Š-1 trainer variant with a 100 hp 6-cyl Breitfeld & Danek Blesk (Czech Mercedes DI) engine.

The Letov Š-5 was an Š-1 modified for evaporate cooling trials.

The primary user was the Czechoslovakian Air Force.

SH-1 / Š.1
Engine: 1 × Hiero 6L inline engine, 169 kW (230 hp)
Wingspan: 13.23 m (43 ft 4.75 in)
Length: 8.31 m / 27 ft 3 in
Height: 3.10m / 10 ft 2 in
Empty weight: 861 kg
Max takeoff weight: 1,375 kg (3,031 lb)
Maximum speed: 194 km/h (120 mph)
Range: 715 km / 445 miles
Climb to 5000 m: 52 min
Service ceiling: 6,000 m / 19,685 ft
Crew: 2
Armament: 1x fixed machine gun, 1x twin machine gun on swivel mount

SM-1 / Š.2
Engine: 1 x 260hp Maybach Mb.IVa
Max take-off weight: 1492 kg / 3289 lb
Empty weight: 970 kg / 2138 lb
Wingspan: 13.02 m / 43 ft 9 in
Length: 8.52 m / 28 ft 11 in
Height: 3.31 m / 11 ft 10 in
Wing area: 36.17 sq.m / 389.33 sq ft
Max. speed: 198 km/h / 123 mph
Cruise speed: 167 km/h / 104 mph
Ceiling: 6500 m / 21350 ft
Range: 667 km / 414 miles
Armament: 3 x 7.7mm, 120kg of bombs
Crew: 2

Š.10
Engine: 100 hp 6-cyl Breitfeld & Danek Blesk