Draft:Avia S-92

Avia S-92 Turbina
Avia S-92 on display at Prague Aviation Museum, Kbely
General information
Type	Fighter aircraft / Jet trainer
Manufacturer	Avia
Designer	Messerschmitt
Status	Retired
Primary users	Czechoslovak Air Force Israeli Air Force (alleged)
Number built	12 (9 fighters, 3 trainers)
History
Introduction date	1948
First flight	27 August 1946
Retired	1951
Developed from	Messerschmitt Me 262
Variants	CS-92 (two-seat trainer)

The Avia S-92, nicknamed "Turbina" ("Turbine"), was a Czechoslovak-built jet fighter developed immediately after World War II. Essentially a continuation of the German Messerschmitt Me 262A-1a Schwalbe, the S-92 was produced using captured German airframe components, jet engines, and technical blueprints left behind in Czechoslovakia. It became the first operational jet fighter to serve with the Czechoslovak Air Force in the late 1940s. A small batch of single-seat fighters and two-seat trainer variants were completed, but the type’s service was short-lived, as more modern Soviet jet fighters soon replaced it by 1951.

Development

During the German occupation of Czechoslovakia in WWII, the Avia aircraft company and other local factories were subcontracted to produce parts for the Messerschmitt Me 262 jet fighter, and plans were in place to commence full Me 262 production in Czechoslovakia. In May 1945, as the war ended, Soviet forces liberated western Czechoslovakia and captured the Me 262 production facilities intact. The Soviets turned over the seized jigs, tooling, and components to the re-established Czechoslovak governmentaviastar.org. As a result, the Czechoslovaks found themselves with complete technical documentation, sub-assemblies, numerous spare parts, and several Junkers Jumo 004 turbojet engines on hand – effectively everything needed to build the Me 262.

Antonín Kraus (1908-1951), Czech test pilot on a prototype of Avia S-92 in 1946

Eager to propel their air force into the jet age, the Czechoslovak Ministry of Defense authorized Avia to resume production of the Me 262 under the new designation S-92 (“S” for stíhací for the single-seat fighter model). By late 1945, Avia had completed assembly of the first prototype airframe at the Letňany Research Institute using an Avia-built fuselage and two Jumo 004 engines (locally overhauled and redesignated M-04). On 27 August 1946, Avia’s chief test pilot Antonín Kraus took this first S-92 prototype (serial S-92.1) on its maiden flight. The flight exposed some issues – it lasted only about 15 minutes and the landing gear could not be fully retracted. Days later, on 31 August, the prototype was lost in a crash (without fatality). Despite this setback, the program pressed ahead. A second prototype (S-92.2) flew on 24 October 1946, and by 10 December 1946 the first two-seat trainer variant (designated CS-92, essentially an Me 262B-1a) had its initial flight.

Further examples were built over the next few years. Production was neither easy nor rapid, with each S-92 was essentially hand-assembled, requiring an estimated 7,000 man-hours per aircraft. Avia managed to utilize enough captured components to plan for up to 17 airframes, but in practice a smaller number were completed. Early in the project it became clear that a dual-control trainer was needed to transition pilots to jets, so three two-seat CS-92s were included, identical to the fighters except that a second seat replaced some fuel tank capacity. One S-92 airframe (the seventh built) was experimentally fitted with alternative BMW 003 turbojet engines (which offered slightly higher thrust of ~950 kgf each), but this retrofit proved unsuccessful. Test flights showed reliability problems, and the aircraft was promptly re-engined with the standard Jumo 004 units. By 1949, the final S-92s were completed and the limited production run came to an end.

Design and technical characteristics

In design, the Avia S-92 was a part-for-part copy of the wartime Me 262A jet fighter, with only minimal local modifications. The airframe, aerodynamic layout, and systems were essentially identical to the German design. Notably, the Czechoslovak-built examples did not carry the underwing rocket racks for R4M air-to-air rockets that some late-war Me 262s had, but they retained the same nose armament of four MK 108 30 mm cannons. The powerplant was the Junkers Jumo 004B axial-flow turbojet, produced during the war by Walter Aircraft Engines in Prague; Avia overhauled these engines post-war and designated them M-04. Each S-92 carried two M-04 engines, each rated at approximately 8.8 kN (1,980 lbf) of thrust, feeding from the Me 262’s original fuel system. Avia’s careful refurbishing of the engines and peacetime operating procedures managed to double the typical service life of the powerplants. Czechoslovak pilots reported up to ~60 flight hours between overhauls on the M-04, whereas wartime German Jumo 004s often lasted only 25–50 hours. This longevity improvement was largely attributed to gentler throttle handling and meticulous maintenance in a non-combat environment.

The S-92’s performance remained on par with the original Me 262A. It was a fast aircraft by late-1940s standards, easily outpacing any piston-engine fighters. However, like the Me 262, it suffered from the early turbojets’ drawbacks (such as sluggish throttle response and occasional flameouts or asymmetric thrust issues). Once pilots mastered these quirks, the S-92 was still considered a competent fighter for its time. Czechoslovak evaluations noted it was less maneuverable in a tight turn than contemporary prop fighters like the Lavochkin La-7, but its speed and ability to retain lift in jet-powered sustained turns made it formidable. The key specifications of Avia S-92 were as follows:

• Configuration: Single-seat, twin-engine jet fighter (S-92). Tandem two-seat trainer (CS-92 variant) with dual controls.
• Powerplant: 2 × Malesice M-04 axial-flow turbojets (Junkers Jumo 004B), ~8.8 kN thrust each.
• Dimensions: Wingspan 12.50 m (41 ft 0 in); Length 10.58 m (34 ft 9 in); Height 3.83 m (12 ft 7 in); Wing area 21.8 m²
• Weights: ~4,000 kg empty; 7,045 kg maximum takeoff weight.
• Performance: Top speed ~870 km/h (540 mph); service ceiling ~11,450 m (37,550 ft); climb rate ~1,220 m/min (4,000 ft/min); range ~1,050 km (650 mi).
• Armament: 4 × 30 mm MK 108 autocannon in nose (single-seat fighter). Note: Two-seat CS-92 carried the same armament but with reduced internal fuel capacity. No provision for rockets or bombs was utilized post-war.

Production and variants

Avia CS-92 A, painted under false German marking

The Avia S-92 program was very limited in scale. In total, only 12 airframes were completed by Avia between 1946 and 1949. These comprised 9 single-seat S-92 (“S” for stíhací – fighter) fighters (equivalent to Me 262A-1a) and 3 two-seat CS-92 trainers (equivalent to Me 262B-1a). The aircraft were serial-numbered S-92.1 through S-92.9 and CS-92.3, .5, .7 (the numbering was shared in one sequence, reflecting the order of assembly). As noted, the CS-92 (“CS” likely for cvičný stíhací – training fighter) variants were essentially identical to the standard fighter except for a second cockpit added at the expense of some fuel volume. This allowed an instructor pilot to train a student, a crucial addition, since the jump from propeller fighters to jets was non-trivial for new pilots in the late 1940s.

Despite plans and components to potentially build more, Avia did not produce beyond these 12 units. By the late 1940s, Czechoslovakia was aligning with the Eastern Bloc and newer jet technology was becoming available from the Soviet Union. Avia had already begun work on license-producing the Soviet Yakovlev Yak-23 jet (designated S-101 in Czech service) in 1949, and more importantly was angling for a license to build the superior Mikoyan-Gurevich MiG-15 fighter. Continuing to hand-build an outdated German design was seen as an impediment to these modern projects. Indeed, once the MiG-15 production license was granted, the S-92 assembly line was promptly shut down to free up resources.

Another factor that curtailed S-92 production was the issue of spare parts and armament standardization. The S-92’s MK 108 cannons fired unique 30 × 90 mm ammunition that was left over from German WWII stocks. By 1948–49, Czechoslovakia was trying to streamline logistics by focusing on either Western (ex-German and British) or Soviet calibers; producing ammo for a handful of Me 262-derived jets was low priority. Combined with the increasing difficulty of maintaining the Jumo/M-04 engines (which, even with careful use, had to be completely scrapped after roughly 300 total hours of operation due to metal fatigue issues), the rationale for building more S-92s simply faded.

Operational history

In Czechoslovakia

The S-92 and CS-92 were introduced into Czechoslovak Air Force service in the late 1940s, marking the country’s entry into the jet age. After flight testing and acceptance, the first S-92 was officially delivered to the air force on 6 February 1948, and by 1950 the jets were formed into a dedicated jet fighter unit. A special all-jet detachment within the 5th Fighter Squadron (based at Prague–Kbely airbase) was equipped with the S-92 and CS-92. This unit’s role was primarily to train pilots on jet operations and to provide air defense for the capital, Prague. The S-92s flew as interceptors guarding the city, but given the peacetime conditions of the late 1940s, they never saw actual combat. Lacking radar and carrying limited fuel (especially the two-seaters), their practical use was confined to daytime interception and familiarization flights. Still, for Czech pilots transitioning from pistons to jets, the experience was invaluable. Pilots noted that the S-92 was roughly 270 km/h faster than the best piston fighter in the fleet (the La-7) and gave Czechoslovakia a brief technological edge in the immediate post-war region.

By 1950, however, the writing was on the wall for the S-92. The Czechoslovak Air Force began receiving its first truly modern jet fighters, the Soviet-built MiG-15 and two-seat MiG-15UTI trainers, which far outperformed the older German-designed machines. In mid-1950 the S-92s were officially withdrawn from frontline 5th Squadron service and reassigned as ground instructional airframes for technical training at various aviation schools. The three CS-92 trainers continued flying slightly longer (for proficiency and transition training) until 1951, but by the end of 1951 all S-92/CS-92 aircraft had been permanently retired from flying status. The brief era of the “Turbina” had come to a close just four years after it began.

In total, the S-92s served operationally for only a few years and did not participate in any armed conflict. Nonetheless, they hold the distinction of being the first jet-propelled fighters in Czechoslovak service and a bridge to the more advanced jet age of the 1950s. Several of the airframes were preserved rather than immediately scrapped. They were stored in the National Technical Museum, the Prague Aviation museum in Kbely, and elsewhere. At least one S-92 was kept airworthy for a short time to perform taxi runs or engine tests, but no flights were recorded beyond 1951.