"Troikaschlepp" arrangement to get the Messerschmitt Me 321 Gigant cargo glider airborne

The Messerschmitt Me 321 Gigant was a large German cargo glider developed and used during World War II. Intended to support large scale invasions, the Me 321 saw very limited use due to the low availability of suitable tug aircraft, high vulnerability whilst in flight and the difficult ground handling, both at base and at destination landing sites.

The first flight of the prototype Me 321 V1 took place on February 25th 1941, towed into the air by a Ju 90. It was piloted by Messerschmitt test pilot Karl Baur, and carried 3 tonnes (3 tons) of ballast. Baur reported that the controls were heavy and responses sluggish. It was decided to enlarge the cockpit to accommodate a co-pilot and radio operator, and dual controls were fitted. Electric servo motors were also fitted to assist in moving the huge trailing edge flaps and further tests caused a braking parachute to also be added.

The test flights were plagued by takeoff difficulties, since the Junkers Ju 90 was not powerful enough, and as an interim measure three Bf 110 heavy fighters were used, in a so-called Troikaschlepp, with the trio of twin-engined fighters taking off together in a V formation. This was a highly dangerous maneuver and Ernst Udet asked Ernst Heinkel to come up with a better aerial towing method. Heinkel responded by creating the Heinkel He 111Z Zwilling ("Twins"), which combined two He 111 aircraft through the use of a new "center" wing section with a fifth engine added. Underwing-mount, liquid monopropellant Walter HWK 109-500 Starthilfe rocket-assisted takeoff booster units were also used to assist takeoff from rough fields.