Boeing 377: Wikis


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Boeing 377 Stratocruiser
Pan Am Boeing Stratocruiser "Clipper Seven Seas" arriving at London (Heathrow) in September 1954
Role Airliner
Manufacturer Boeing
First flight 8 July 1947
Primary users Pan Am
Number built 56
Developed from C-97 Stratofreighter
Variants Pregnant Guppy
Super Guppy
Mini Guppy

The Boeing 377 Stratocruiser was a luxurious long-range postwar airliner with four piston-driven engines. It was a civilian version of the C-97 Stratofreighter.


Design and development

Like the C-97, the 377 was developed towards the end of World War II by adapting an enlarged upper fuselage onto the lower fuselage and wings which were essentially the same as the B-50 Superfortress, the high-performance evolution of the B-29 Superfortress bomber. The 377 was larger and longer ranged than the Lockheed Constellation and Douglas DC-6, with nonstop transatlantic range eastbound, but the P&W R-4360 Wasp Major engines proved uneconomical, with production ending in 1950. [1]

The "inverted-figure-8" doubledeck fuselage design provided 6,600 ft³ (187 m³) of interior space where the lower deck had a smaller diameter than the upper deck. It offered seating for over 100 passengers, or sleeping berths for up to 28 berthed and five seated passengers. It first flew on July 8, 1947. It had the speed and range to span ocean routes, enabling flying from New York to Hawaii in less than 24 hours.[2] Pressurization (previously introduced on the Boeing Stratoliner and also designed into the B-29) allowed sea-level cabin pressure at 15,500 ft (4,700 m) of altitude. At 25,000 ft (7,600 m), passengers enjoyed a “cabin altitude” of only 5,500 ft (1,700 m).

Operational history

Despite serious design flaws and a marginal service record,[3] the Stratocruiser was one of the most luxurious post-war propeller airliners. Extremely complex and expensive, only 56 were built as airliners. Another 60 of this design were built as C-97 military transports, but the majority were built as 816 KC-97 tankers.

The Stratocruiser served as flagships on the Atlantic and Hawaii runs until forced out of service by the 1960s, when it was made obsolete by the coming of jet airliners such as the Boeing 707 and de Havilland Comet. Its spiral staircase, which led to a lower-deck lounge, inspired the one on the 747. It was one of the few airliners with a double-decker seating arrangement (another was the French Breguet Deux-Ponts) until the 747, though some airlines did have lower-level lounges on their L-1011 Tristar aircraft. The only survivors are converted Super Guppies.


American Overseas Airways Stratocruiser.
BOAC Stratocruiser G-AKGJ "RMA Cambria" at Manchester operating a New York flight in 1954
  • Línea Internacional Aérea
 United Kingdom
 United States
  • Rutas Aéreas Nacionales SA
 Denmark  Sweden  Norway

Safety record

  • This aircraft type suffered 13 hull-loss accidents between 1951 and 1970 with a total of 140 fatalities. The worst single accident occurred on April 29, 1952; separation of the number two engine and propeller from Pan Am Flight 202 caused it to crash in the jungle near Carolina, Brazil, killing all forty-one passengers and nine crew.
  • In April 1956, Northwest Orient Airlines Flight 2 ditched into Puget Sound after the flight engineer forgot to close the cowl gills on the plane's engines. Although all aboard escaped the aircraft after a textbook landing, four passengers and one flight attendant succumbed either to drowning or to hypothermia before being rescued. The survival rate was 87%.
  • In October 1956, Pan Am Flight 6 ditched northeast of Hawaii, after losing two of its four engines. The aircraft was able to circle around USCGC Pontchartrain until daybreak, when it ditched; all 31 on board survived.
  • The Romance of the Skies, Pan Am Flight 7, left San Francisco on November 8, 1957, headed for Hawaii with 38 passengers and 6 crew. The 377 suffered a mechanical failure that may have been sabotage, and crashed around 5:25pm in the Pacific. There were no survivors. There is speculation that two passengers had a motive to bring the plane down. Eugene Crosthwaite, a 46 year old purser, had shown blasting powder to a relative days prior to the flight, and had cut a stepdaughter from his will only one hour before the flight. William Payne, an ex-Navy demolitions expert, had taken out large insurance policies on himself just before the flight, and had a $10,000 debt he was desperate to pay off. The insurance investigator later suspected him of never being on the plane. His wife received at least $125,000 in payouts.

Aero Spacelines/Guppys

The Pregnant Guppy heavy lifter.

In the 1960s, Aero Spacelines modified several Stratocruisers to make oversized transports dubbed "Guppys". The first of these was the Pregnant Guppy, followed by the Super Guppy, and finally the Mini Guppy.

Specifications (377)

Data from Airliners of the World[4]

General characteristics

  • Capacity: Up to 100 passengers on main deck plus 14 in lower deck lounge; typical seating for 63 or 84 passengers or 28 berthed and five seated passengers.
  • 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:Pratt & Whitney R-4360-B6 Wasp Major 28-cylinder radial engines four-bladed propellers, 3,500 hp (2,610 kW) each


See also

Related development

Comparable aircraft


  1. ^ Pushing the Envelope: The American Aircraft Industry By Donald M. Pattillo
  2. ^ Stratcruiser
  3. ^ Ernest K. Gann's Flying Circus: Lady with a past
  4. ^ Wilson, Stewart (1999). Airliners of the World. Fyshwick, Australia: Aerospace Publications. ISBN 1-875671-44-7.  

External links

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