The Siebel Si 204 was a small twin-engined transport and trainer aircraft developed in World War II. It was based on the Siebel Fh 104 Hallore. Originally designed in response to a German Ministry of Aviation development order for a small civil transport aircraft in 1938, it was eventually produced for the Luftwaffe.
The Si 204 was planned as a small all-metal passenger aircraft with two crew and eight passengers for German airline Deutsche Luft Hansa (DLH). Development was initiated in 1938. The contractor was, as usual, the RLM, but the development was conducted in close collaboration between DLH and Siebel in Halle.
After the beginning of the war, the aircraft was redesigned as a trainer aircraft with a full "stepless" glass cockpit, as had been initiated with the He 111P in early 1938, with no separate flat windscreen for the pilot (much as almost all German bomber aircraft of the time were being designed), which seemed to be better for instrument flying in the Si 204's case.
The first two prototypes only were delivered as passenger aircraft with the old cockpit. The maiden flight of the first prototype was before September 1940, possibly on 25 May 1940, that of the second prototype before February 1941. The third prototype was redesigned as a trainer aircraft for instrument flying. As a result of this, the maiden flight was not earlier than the end of 1941 or the beginning of 1942.
At that time, Siebel produced the Junkers Ju 88 under licence, so only 15 prototypes were able to be built in Halle. As a result, Société Nationale de Constructions Aéronautiques du Nord (SNCAN) in France produced the A-0 preseries and A-1 production passenger aircraft between April 1942 and November 1943.
Českomoravská Kolben-Daněk (ČKD, called Böhmisch-Mährische Maschinenfabrik AG [BMM] in German) in the Protectorate of Bohemia and Moravia delivered the first instrument flight trainer D-0 in January 1943 followed by production of a further 44 D-0 preseries aircraft. The D-1 series was begun in March 1943 by Aero, also in the Protectorate, and by BMM in June or July 1943. In August 1943, SNCAN also delivered their first D-1.
Production of the D-3 was started in October 1944 by Aero Vodochody. The D-3 had wooden wings and a tail-plane made of wood and metal. French production of the D-1 was ended in August 1944 after the Liberation. SNCAN produced a total of 168 units of the Si 204. BMM produced the aircraft until October 1944 and then changed to producing spare parts for the Si 204. The Aero company was scheduled to cease production of the D-1 in March 1945 after building 486 aircraft and then switch to D-3 only. The aircraft, however, was only built until January 1945 with 541 completed.
Therefore, total production was 1,216 (until January 1945) including the prototypes; some production in other countries continued after the war ended.
The Si 204D was used mainly in B- and C-Schools (advanced schools) and in FÜG 1 (delivery wing of the Luftwaffe), probably as a taxi aircraft for crews who had delivered other aircraft to fighting units. Its use in instrument flight schools was sporadic; for radio schools, no evidence of use has been found. The Si 204A flew mainly with communications squadrons and flying services for senior officers, but also with schools.
In July 1944, five Si 204 were destined to be converted to night-combat aircraft, but no further aircraft were allotted. They were probably intended for the pre-series Si 204 E-0. However, no evidence shows that these aircraft were ever used in combat situations.
Luft Hansa received at least four Si 204s: The first prototype, D-AEFR, was evaluated from March to May 1941 by Luft Hansa Prague. From spring 1942 to spring 1943, the second prototype, D-ASGU, was used on regular routes as a freight carrier.
An Si 204 was likely the last German aircraft shot down on the Western Front. At 8 p.m. on May 8, 1945, 2nd Lt. K. L. Smith of the 9th Air Force's 474th Fighter Group, flying a P-38 Lightning, downed a Siebel 3 miles southeast of Rodach, Bavaria.[1]
At the end of the war, one Si 204D remained in Berlin-Tempelhof (named "Rhein"). One flew to Enns in Austria, where it was captured by the Allies.
Captured Si 204s flew in a variety of civil roles in the post-war USSR, serving with Aeroflot until 1949, being particularly successful in Tajikistan regional services. Soviet Polar Aviation flew seven Si 204s, equipped with skis, in Siberia. Major engine deficiencies in the extreme climate conditions, with four aircraft lost, caused local aircrew to nickname the Si 204 Giebel, Russian for disaster, before withdrawal from the region. The last Soviet Si 204, flying with the Agricultural Survey, was retired in 1951.[2]
| Version | Engine | Usage | First Flight | Fate | |
|---|---|---|---|---|---|
| V1 | As 410 | Prototype passenger plane, Reg. D-AEFR | 25 May 1940? | Not mentioned in November 1942, scrapped? | |
| V2 | As 410 | Prototype passenger aircraft, Reg. D-ASGU | Before February 1941 | 26.02.44 Crash Erprobungs-Stelle Rechlin | |
| V3 | As 410 | Prototype instrument flight trainer aircraft | Before February 1942 | 01.06.42 Crash Erprobungs-Stelle Rechlin | |
| V4 | As 411 | Prototype instrument flight trainer aircraft, Reg. KM+GB | Before November 1942 | ||
| V5 | For stress testing | ||||
| V6 | As 410 | Evaluation As 410 | December 1942 | ||
| V7 | As 410 | Weather reconnaissance | |||
| V8 | As 410 | General flight evaluation | |||
| V9 | As 410 | General flight evaluation | 30.06.43 Crash School C-16 Burg | ||
| V10 | As 410 | General flight evaluation | |||
| V11 | As 410 | General flight evaluation | |||
| V12 | As 410 | General flight evaluation | 13.03.44 Crash Erprobungs-Stelle Rechlin | ||
| V13 | As 410 | General flight evaluation | |||
| V14 | As 411 | Prototype D-2 | |||
| V15 | As 411 | Evaluation As 411 |
Production figures of the Si 204 until 31 January 1945:
| Version | Siebel | SNCAC | BMM/ČKD | Aero | SUM | |
|---|---|---|---|---|---|---|
| Prototypes | 15 | 15 | ||||
| A-0 | 30 | 30 | ||||
| A-1 | 85 | 85 | ||||
| D-0 | 45 | 45 | ||||
| D-1 | 53 | 447 | 477 | 977 | ||
| D-3 | 64 | 64 | ||||
| SUM | 15 | 168 | 492 | 541 | 1.216 |
After the war, a production of Si 204 continued in Czechoslovakia and France. In Czechoslovakia Aero Vodochody produced 179 Si 204D, developed into military trainer variants Aero C-3A and C-3B (the latter for bombardier training), passenger variant C-103 and military transport variant Aero D-44 until 1949. In France SNCAC (Société Nationale de Constructions Aéronautiques du Centre), commonly known as Aérocentre, produced 240 transport NC.701 Martinets and a number (110?) of passenger NC.702 Martinets.[3] The NC.701 was distinguished by three-blade propellers and was powered by 440 kW (590 hp) Renault 12S-00 engines. The NC.702 had a modified nose.[4]
Slovakia