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Boeing 377 Stratocruiser
Pan Am Stratocruiser Clipper Seven Seas arriving at London Heathrow in September 1954.
Role Airliner
Manufacturer Boeing
First flight July 8, 1947
Retired 1963
Status Retired
Primary user Pan Am
Number built 56
Developed from Boeing C-97 Stratofreighter
Variants Pregnant Guppy
Super Guppy
Mini Guppy

The Boeing 377, sometimes called the Stratocruiser, was an airliner made by Boeing after World War II. It was made from the C-97 Stratofreighter, which was a type of Boeing B-29 Superfortress used to move troops around. The Stratocruiser first took off on July 8, 1947.

The Stratocruiser had four piston engines. It had a pressurized cabin and two decks. Airlines could fly for much longer with the Stratocruiser, to places like Hawaii.

However, the Stratocruiser was a lot more expensive than the Douglas DC-6 and Lockheed Constellation. Only 55 Stratocruisers were made for airlines.

Design and development

The Boeing 377 used the bottom and the wings of the B-50 Superfortress. The 377 was bigger than the Lockheed Constellation and Douglas DC-6 and it could fly for longer. Boeing stopped making the 377 in 1950.

Pressurization (first used on the Boeing 307) meant that if the plane was flying at 15,500 ft (4,700 m), to the passengers it would be like they were on the ground.


56 Stratocruisers were made. 55 of these were made for airlines.

The Stratocruiser flew to Hawaii as well as many other places. It was one of the only planes with two decks (another one was the Breguet Deux-Ponts) until the Boeing 747 was made.

In the early 1960s the Stratocruiser was overtaken by jet planes like the de Havilland Comet, Boeing 707 and Douglas DC-8.

Different types of Boeing 377

Prototype. It was given to Pan American World Airways in 1950.
20 given to Pan American World Airways.
10 aircraft with better engines and more fuel. It was called the "Super Stratocruiser".

Many other types were made, but most of them only had changes made to the shape of the windows.

Aero Spacelines Guppy

Pregnant Guppy NASA
The Pregnant Guppy

A company called Aero Spacelines started changing 377s to planes called Guppies in 1960s. There were three types: the Pregnant Guppy, Super Guppy, and Mini Guppy.

The first of them was the Pregnant Guppy. After this they made the Super Guppy and then the Mini Guppy. The Super Guppy and the Mini Guppy had turboprop engines.


Boeing 377 Stratocruiser (B-29) American Overseas 1949-50
American Overseas Airways Stratocruiser
BOAC Stratocruiser at Manchester 1954
BOAC Stratocruiser G-AKGJ "RMA Cambria" at Manchester operating a New York flight in 1954
  • Línea Internacional Aérea
  • Israeli Air Force
United Kingdom
United States
  • Rutas Aéreas Nacionales SA


Pan Am Flight 6

The Stratocruiser had 13 hull-loss accidents between 1951 and 1970. A hull-loss accident is when a plane is damaged so badly it cannot be fixed. 140 people died in these. The worst accident happened on April 29, 1952.

Details (377)

Data from Airliners of the World

General characteristics

  • Length: 110 ft 4 in (33.63 m)
  • Wingspan: 141 ft 3 in (43.05 m)
  • Height: 38 ft 3 in (11.66 m)
  • Wing area: 1769 ft² (164.3 m²)
  • Empty weight: 83,500 lb (37,876 kg)
  • Max. takeoff weight: 148,000 lb (67,133 kg)
  • Powerplant: 4 × Pratt & Whitney R-4360-B6 Wasp Major four-bladed propellers, 3,500 hp (2,610 kW) each


  • Maximum speed: 375 mph (603 km/h)
  • Cruise speed: 301 mph (483 km/h)
  • Range: 4,200 mi (3,650 nmi, 6,760 km)
  • Service ceiling: 32,000 ft (9,800 m)

Related pages

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