WWII Engineers Combined Two Bombers to Create Aircraft for Towing Larger Planes

In early 1944, a British reconnaissance pilot flying a Spitfire over northern France reported seeing something unusual. It looked like two German Heinkel 111 bombers fused into one aircraft. At first, British intelligence dismissed the claim, thinking the pilot had misinterpreted a close formation of planes. But soon after, a Royal Air Force Mosquito shot down an aircraft fitting that description, along with two Gotha gliders it was towing. The existence of this strange design was finally confirmed. The aircraft was the Heinkel He 111Z, a special-purpose towing plane developed by German engineers.

The He 111Z Project and the Challenges of the Me 321 “Gigant” Glider

The He 111Z project began in 1941. The goal was to create a powerful aircraft capable of towing the Messerschmitt Me 321, a massive cargo glider. This glider, known as the “Gigant” (Giant), had been developed for Operation Sea Lion, the planned invasion of Britain. When that plan was abandoned after Germany failed to gain air superiority in the Battle of Britain, the Me 321 was repurposed for transport operations, particularly on the Eastern Front.

The Me 321 was far larger than standard German transport planes. It had a wingspan of 180 feet (55 meters) and could carry 130 soldiers or about 23 tons of supplies. This was more than six times the capacity of the Junkers Ju 52, Germany’s primary transport plane at the time. Unlike the Ju 52, the Me 321 could also transport armored vehicles, making it valuable for resupplying troops deep into Soviet territory. However, getting the enormous glider into the air was a major challenge. The initial solution involved using three Messerschmitt Bf 110 twin-engine fighters in a complex and dangerous towing formation. This method proved too risky and unreliable.

Development and Operational Challenges of the He 111Z Towing Aircraft

To solve the problem, the Heinkel company proposed joining two He 111 medium bombers with a reinforced wing center section and adding a fifth engine between them. This design created a more powerful towing aircraft, the He 111Z, which entered service in 1942. Despite having a combined engine power of 6,500 horsepower—far more than modern cargo planes like the C-130 Hercules—it still struggled to tow a fully loaded Me 321. Engineers added rocket-assisted takeoff boosters, which were jettisoned after takeoff and recovered for reuse.

The He 111Z had a crew of seven. The left fuselage housed the main pilot, chief mechanic, radio operator, navigator, and a gunner. The right fuselage contained the co-pilot, an additional mechanic, and another gunner. The aircraft had an impressive range of over 1,200 miles (1,900 kilometers), which could be extended to 10 hours of flight with extra fuel tanks. Despite its range, it was highly vulnerable due to its slow towing speed of just 130 miles per hour (209 kilometers per hour). This made it easy prey for Allied fighters like the P-51 Mustang, which could fly at more than three times that speed. As a result, the He 111Z was kept away from front-line combat zones whenever possible.

Limited Deployment and Unrealized Potential of the He 111Z Aircraft

In 1942, German high command considered using the He 111Z to support an invasion of Malta and later to resupply the German Sixth Army trapped at Stalingrad. However, these plans were abandoned due to the aircraft’s vulnerability. In total, only twelve He 111Zs were built, and they were used primarily to tow around 200 Me 321 gliders.

The German air force had hoped to develop other versions of the He 111Z, including a heavy bomber and a long-range reconnaissance variant, but none of these advanced beyond the planning stage. The aircraft remained a rare and unusual design, created out of necessity but limited in its effectiveness due to the changing conditions of the war.