Time Period: Post-WW2
Country of Origin: Soviet Union / Russia
Type: Prototypes and Experimental
Manufacturer: Konstantin Kalinin (designer)
Kalinin K-7 Aircraft Overview
In the early 1930s, the Soviet Union was dreaming big — and nowhere was that dream more outrageous than in the sky. Designed by Konstantin Kalinin, the K-7 was an experimental heavy bomber and troop transport intended to showcase Soviet engineering power. It was meant to carry soldiers, equipment, and even artillery… in the air.
But it wasn’t just big — it was huge. With a wingspan of over 53 meters (174 feet), it rivaled modern jumbo jets. Its thick, load-bearing wing was so massive that passengers could walk inside it, and it was equipped with seven engines: six pusher-propellers on the wing’s trailing edge and a seventh pulling from the front. Twin tail booms and chunky landing gear added to its monster-like silhouette.
The Kalinin K-7 was designed as a multi-role aircraft: capable of acting as a heavy bomber, troop transport, or even a civilian airliner. One version was supposed to carry 120 passengers, while the military variant could transport 112 troops or a significant payload of bombs and defensive weapons. It was meant to be an airborne city, complete with gun turrets for defense.
The structure was mostly built from metal, unusual for the time, and the plane was full of novel features. But the sheer scale of it pushed technology to its limit—and then some.
How Did the K-7 Fly?
Surprisingly, the K-7 did fly. Its first flight took place in 1933, and despite its unwieldy shape and mechanical complexity, it got off the ground. But the test program quickly revealed serious flaws: vibrations in the tail booms, structural instability, and underpowered engines. After just seven test flights, disaster struck. During one flight, the aircraft suffered a structural failure, causing it to crash and killing 14 people.
The accident and the aircraft’s engineering issues led to the cancellation of further development. Additional prototypes were planned but never completed.
Where Is It Now?
The Kalinin K-7 was a one-of-a-kind machine. No other versions survived, and no replicas have ever been built. All that remains are photographs, blueprints, and scale models, along with a near-mythical status in aviation circles. It’s a classic example of ambition outpacing practicality—a bold, beautiful failure that aimed high but fell short.
Kalinin K-7 Specifications
- Length: Approximately 28 meters (91 feet 10 inches)
- Wingspan: Around 53 meters (173 feet 11 inches)
- Estimated Height: 12.4 meters (40 feet 8 inches) to the top of the engine nacelles
- Wing Area: A massive 454 square meters (4,890 sq ft)
- Aspect Ratio: 6.2
- Airfoil Design: TsAGI R-II profile, with a 22% thickness at the wing root and 19% at the tips
- Empty Weight: Roughly 24,400 kg (53,793 lbs)
- Normal Loaded Weight: About 38,000 kg (83,776 lbs)Maximum Bomb Load Configuration: 42,400 kg (93,500 lbs)
- Maximum Takeoff Weight: 46,500 kg (102,515 lbs)
- Fuel Capacity: 9,130 liters (approx. 2,410 US gallons), stored in the wing tanks
- Engines: Powered by seven Mikulin AM-34F liquid-cooled V-12 piston engines, each producing 560 kW (750 hp)
- Propellers: Each engine drove a fixed-pitch, two-bladed propeller
Kalinin K-7 Performance
- Top Speed: Up to 225 km/h (140 mph or 121 knots)
- Cruising Speed: Around 180 km/h (110 mph or 97 knots)
- Range: Capable of flying up to 1,600 kilometers (990 miles or 860 nautical miles)
- Service Ceiling: Operational altitude of approximately 4,000 meters (13,000 feet)
- Wing Loading: 84 kg/m² (17 lbs/sq ft)
- Power-to-Weight Ratio: Approximately 0.084 kW/kg (0.051 hp/lb)
Kalinin K-7 Armament
- Cannons: At least three 20 mm cannons, located in the nose and tail boom tips
- Machine Guns: A minimum of eight 7.62 mm (0.30 caliber) machine guns, spread across gondolas and defensive positions
- Bomb Capacity: Could carry up to 19,000 kg (42,000 lbs) of bombs in its maximum payload configuration
Kalinin K-7 Image Gallery
The Kalinin K-7 wasn’t just an airplane — it was a symbol of 1930s Soviet ambition: monumental, experimental, and fearless. While it never became the sky-dominating beast its creators envisioned, it remains one of the most fascinating aircraft ever built. It’s a story of innovation, risk, and the boundaries of aviation pushed to their breaking point.
