Nazi Germany (1942)
Light Transport and Trainer – 1,216 Built

The Siebel Si 204 was a twin engined light transport and trainer aircraft built by Siebel for the Luftwaffe in World War II.

History

The story of the “Siebel” factory starts in the 1934, with the founding of “Hans Klemm – Flugzeugwerke Halle“ that was a branch of “Leichtflugzeugbau Klemmin Böblingen”. In December 1937 the name changed to “Siebel Flugzeugwerke“ when it was taken over by Friedrich Siebel.

Initially Siebel had a license to produce the Focke-Wulf Fw 44 “Stieglitz” and later during the war Heinkel He 46, Dornier Do 17 and the Junkers Ju-88. In addition to the production of licensed aircraft, in 1937, “Siebel” produced its own aircraft under the name Fh 104. It had its first test flight that same year, and some 46 planes where build during the period of 1938-42. The Fh 104 made a number of notewortly flights:

• In March of 1939 flying a 39975 km tour of Africa,
• Winning the “Littorio rally in Italy”,
• And flying a 6200 km across 12 countries in 1938 (Europa Rundflug).

By the end of 1930, “Siebel” company was commissioned by the Luftwaffe to design a new type of all-metal twin-light light transport aircraft with a capacity of eight persons with two crew members. In 1940 the first prototype of the twin engine and larger and also heavier Si 204 appeared with originally a conventional stepped cockpit and a powerplant of two 360 hp (268 kW) Argus As 410 engines . The prototype made its first flight during the period of May to September 1940. Second prototype made it first test flight in early 1941. The third prototype was re-designed as a trainer aircraft for blind flying. Because of this, its first test flight was only possible at the end of 1941 or the beginning of 1942. The other 12 planes produced by “Siebel” were used for general flight evaluation. After this small production run Siebel stopped building this aircraft, and future planes would be built in France and Czechoslovakia.

Model A was build in relatively small number by the French “SNCAC” (Société Nationale de Constructions Aéronautiques du Nord) factory. It was designed as a transport and communication aircraft.

The next model D appeared in 1942, with a new glazed nose and cockpit with no separate flat windscreen for the pilot. Almost all German bomber aircraft during the war shared this design. The D model also had more powerful 600 hp As 411 engines. The D  model was used for radio navigation and for training. This model was mostly used during the war.

The production of the D-3 version start in October 1944 by the “Aero” company. The D-3 had wooden wings and a tail-plane made of wood because due to material shortages. In France, production of this aircraft was stopped in August 1944 as a result of the Liberation.

“BMM” produced the aircraft until October 1944 and then changed to producing spare parts for the Si 204. The “Aero” was scheduled to cease production of the D-1 in March 1945 after building 486 aircraft and then switch to D-3 only. The E version was built in limited numbers and can be considered as an experimental series.

After the war, production of Si 204 continued in Czechoslovakia and France. Czechoslovakia produced some 179 Si 204D, developed into military trainer variants Aero C-3A, passenger variant C-103 and military transport variant D-44. France produced 240 transport NC.701 Martinets and a number of passenger NC.702 Martinets.

Operational history

During the war the Luftwaffe put the plane to use for transport, communication while also seeing use as an advanced trainer and blind flying trainer.

It was generally regarded as a good plane, but with some drawbacks like the lack of any armament, which prevented many exercises for the combat training program and possible use as a combat aircraft, although for this role it is not designed.

Designers in Halle had developed few different military projects, like installing bomb racks, machine gun turrets and other necessary equipment, but none of these plans were ever  realized. This problem was attempted to be solved with some modified Si 204D airplanes with three 13mm MG 131 machine guns, intended to be used as a night combat aircraft but this model was not used in combat and was built in limited numbers.

Despite these unsuccessful attempts, Germans tried to make a new bomber variant, in order to be used in anti guerrilla fighting with a built to this specification. Three Si-204E were sent to the military tests in Belarus. They were treated as special anti-guerrilla aircraft. The scope of the actions of the Belarusian partisans forced the Germans to throw against them not only regular troops, but armored vehicles and aircraft. The extent to which they were used in this  role remains unknown.

Si 204 is reported to has the “honor”, of being the last German aircraft shot down on the Western Front. On May 8, 1945 an Si 204 was shot down by an American P-38 Lightning, three miles southeast of Rodach, Bavaria.

Production variants

Because Siebel produced the Junkers Ju-88 under licence and the need for as many military aircraft as possible, Germans decided to increase the volume of production for this aircraft. This was done by moving the production to French “SNCAC” and Czechoslovakian “Aero”, and “ČKD-BMM” factories. The “SNCAC” produced some 168 aircraft and the “Aero” and “ČKD-BMM” produced 1033 aircraft, Siebel produced only the first 15 prototype Aircraft, before the production was stop in favor of Ju-88. In total some 1,216 aircraft of this type where build, during the war.

During WW2

• Si 204 – Prototype version with 15 plane build by Siebel (Number V1 to V15),
• Si 204A – Model A was a transport and a communication aircraft, with crew of two and eight passengers.
  • A-0 – Passenger plane version,
  • A-1 – French built version.
• Si 204B and C – Were paper projects
• Si 204D – Model with a new glazed nose and cockpit and with two 600 hp As 411 engines. Model D was used for radio navigation and for flying training.
  • D-0 – Blind flying trainer,
  • D-1 – Czechoslovakian production version,
  • D-3 – This model had wooden wings and tailplanes, in order to save on metal.
• 204E – Experimental night fighter plane. This model had on its nose two 13mm MG 131 machine guns plus one more machine gun (same caliber) in a glazed cupola on the upper hull of the plane. This model was not used in combat and was build in limited number using rebuild Si 204D planes.
  • E-3 – Proposed version to be armed with bombs, and to be used in anty guerrilla fighting, possibly only few were build.
• Flying carrier – Paper project that was originally intended to carry one DM-1 (Doctor Alexander Lippisch plane) on the back of a Siebel Si 204. Little is known about this project

 Postwar

• Czechoslovakia Version:
  • Aero C-3 – Used for flying and crew training,
  • Aero C-103 – Used for Civilian transport,
  • Aero D-44 – Military transport version.
• France versions:
  • SNCAC NC.701 Martinet – Military transport version with SNECMA 12S-00 air-cooled V-12 engines,
  • SNCAC NC.702 Martinet – Improved Passenger transport version.

Operators

• Germany – Most produced planes where used by the Luftwaffe as advanced schools training, transport, blind flying trainer (usage in this role was at best was sporadic) and communication. There were plans for arming this plane for night fighter and anti-partisan operatons, but it all left on paper only with few model build and not a single one was used in combat.
• Czechoslovakia – Used German build planes and the new Aero C-3 version after the war.
• France – Used some captured German planes and also the NC. 701 version which was build by France after the war.
• Hungary – Operated some C-3 Aero version after the war.
• Poland – Used six NC.701 version.
• Soviet Union –They were captured in some numbers at the end of the war. At first, the captured Si-204 was mostly used by the military. The headquarters of many regiments and divisions stationed in Germany used the Siebel for official flights, but only for short period.
• Sweden –  Operated five NC.701 (1962-1970) for mapping photography.
• Switzerland – Operated some Si.204 D planes.

Specifications (Si 204D)
Wingspan	70 ft / 21.33 m
Length	39 ft 3 in / 12 m
Height	14 ft / 4.25 m
Wing Area	495 ft² / 46 m²
Engine	2x Two Argus As 411 12 cylinder inverted piston engines (447kW/600 hp)
Maximum Take-Off Weight	12,346 lb / 5,600 kg
Empty Weight	8,708 lb / 3950 kg
Maximum Speed	226 mph / 364 kmh
Range	1,118 miles / 1,800 km
Maximum Service Ceiling	24,605 ft / 7,500 m
Capacity	8 passengers or up to 3,638 lb / 1,650 kg  cargo

Gallery

Sources

The Hamlyn Concise Guide to Axis Aircraft of World War II, David Mondey, Aerospace Publishing Ltd 1984, 2006., Naoružanje drugog svetskog rata, Namacka-ratno vazduhoplovstva knjiga 2. Duško Nešić. Beograd 2007., http://www.flugzeuginfo.net/acdata_php/acdata_siebel_si204_en.php, https://de.wikipedia.org/wiki/Siebel_Flugzeugwerke, https://en.wikipedia.org/wiki/Siebel_Si_204, http://www.airwar.ru/enc/other2/si204.html, http://www.sas1946.com/main/index.php?topic=19151.0, http://www.secretprojects.co.uk/forum/index.php?topic=3160.0, http://en.valka.cz/topic/view/181034#530924, Images: Side Profile Views by Ed Jackson – Artbyedo.com