The genesis of the Me 323 Gigant (giant) transport was in a 1940 German requirement for a large assault glider. The DFS 230 light glider had already proven its worth in the famous attack on Fort Eben-Emael in Belgium (the first ever assault by gliderborne troops), and would later be used successfully in the Crete invasion in 1941. However, the prospective invasion of Great Britain focused minds on the need to be able to airlift vehicles and other heavy equipment as part of an initial assault wave. Although Operation Sealion was cancelled, the requirement was still a valid one with the focus now on the forthcoming invasion of the USSR.
On October 18 1940, Junkers and Messerschmitt were given just 14 days to submit a proposal for a large transport glider. The emphasis was still very much on the assault role: the ambitious requirement was to be able to carry either an 88mm gun and half-track tractor, or a PzKpfw IV medium tank. The Junkers Ju 322 'Mammut' reached prototype form, but was completely unsatisfactory and was scrapped. The Messerschmitt was originally designated the Me 261w, was then changed to Me 263, eventually becoming the Me 321. Although the Me 321 saw considerable service, it was never used for a Maltese invasion, or for any other such undertakings.
Early in 1941, the decision had been taken to produce a motorized variant of the Me 321. It was now realised that a serious heavy-lift requirement would exist outside the specialized assault role, and that a huge glider that needed specialised towing aircraft, rocket packs and other equipment was simply not the answer. After much study and testing with a converted Me 321 with four engines, it was decided to fit six French Gnome-Rhone GR14N engines. These were in production and readily available, and could easily be bolted on the wing, which consequently needed to be strengthened. A cabin for a flight engineer was added in each wing between the inboard and centre engines, although the pilot could override each engineer’s decision on engine and propeller control. A brand-new permanent landing gear was bolted on to the side of each fuselage, and gave the resulting Me 323 superb rough-field performance. Compared to the Me 321, the Me 323 had a much-reduced payload of between 10–12 tonnes, which was the price that had to be paid for an aircraft that could operate autonomously. Even with the engines, rocket assisted take off packs were still frequently used.
Some ME-321 was converted to ME-323, but the majority was built as 6-engined from the beginning, the early ones had wooden 2-blade propellers which later was replaced by metal 3-blades one.
Capable of carrying 100 combat-equipped troops or a similar freight load of about 15 tons, the Me 323 was used in 1943 to ferry supplies and reserve troops from Italy and Sicily to the German Afrika Korps in Tunis and the area of North Africa. However, from Ultra intelligence, the transport formations' flight schedules were known to the Allies who used this information to send fighter squadron to ambush the aerial convoys and shoot down the transports.
For example, on 22 April 1943 near Cape Bon, several squadrons of Spitfires and P-40 Kittyhawks attacked a unit of 14 petrol-carrying Me 323s and their fighter escorts. All 14 were shot down with the loss of about 120 crew and 700 drums of fuel.
213 Me 323's were built before production ceased in April 1944. There were several production versions, beginning with the D-1. Later D- and E- versions differed in the choice of power plant and in defensive armament, with improvements in structural strength, total cargo load and fuel capacity also being implemented. Nonetheless, the Me 323 remained significantly underpowered. There was a proposal to install six BMW 801 radials, but this never came to pass. The Me 323 was also a short-range aircraft, with a typical range (loaded) of 1,000–1,200 km. Despite this, the limited numbers of Me 323's in service were an invaluable asset to the Germans, and saw intensive use. The Me 323 was something of a 'sitting duck', being so slow and large an aircraft. In the final weeks of the North African campaign in April/May 1943, 43 Gigants were lost, along with much greater numbers of Ju 52's. In terms of aircraft design, the Me 323 was actually very resilient, and could absorb a huge amount of ene my fire, unless loaded with barrels with fuel - the Afrika Korps' nickname of Leukoplastbomber (Elastoplast Bomber) was somewhat unfair. However, no transport aircraft can ever be expected to survive without air superiority or at least, comprehensive local air cover, and it is believed that no Me 323s survived in service beyond the summer of 1944.
(Via: Wikipedia)