The Boeing 377 Stratocruiser was a large long-range airliner developed from the C-97 Stratofreighter military transport, itself a derivative of the B-29 Superfortress. The Stratocruiser's first flight was on July 8, 1947. Its design was advanced for its day; its innovative features included two passenger decks and a pressurized cabin, a relatively new feature on transport aircraft. It could carry up to 100 passengers on the main deck plus 14 in the lower deck lounge; typical seating was for 63 or 84 passengers or 28 berthed and five seated passengers.
The Stratocruiser was larger than the Douglas DC-6 and Lockheed Constellation and cost more to buy and operate. Its reliability was poor, chiefly due to problems with the four 28-cylinder Pratt & Whitney R-4360 Wasp Major radial engines and structural and control problems with their propellers. Only 55 Model 377s were built for airlines, along with the single prototype.
|Boeing 377 Stratocruiser|
|A Pan Am Stratocruiser over San Francisco|
|Role||Long range piston airliner|
|National origin||United States|
|Manufacturer||Boeing Commercial Airplanes|
|First flight||July 8, 1947|
|Introduction||April 1, 1949, with Pan American World Airways|
|Primary user||Pan American World Airways|
|Developed from||Boeing C-97 Stratofreighter|
|Variants||Aero Spacelines Pregnant Guppy|
Aero Spacelines Super Guppy
Aero Spacelines Mini Guppy
The Boeing 377 Stratocruiser was a civil derivative of the Boeing Model 367, the Boeing C-97 Stratofreighter, which first flew in late 1944. William Allen, who had become President of The Boeing Company in September 1945, sought to introduce a new civilian aircraft to replace reduced military production after World War II. Boeing saw in their large-bodied, fast, and long-ranged military transport potential for a passenger aircraft suited for premium service on long transoceanic routes, expanding on the precedent set by their Boeing 314 Clipper with Pan American World Airways. Despite a recession in late 1945, Allen ordered 50 Stratocruisers, spending capital on the project without an order from an airline customer. His gamble that customers would be interested in Boeing's unique and expensive new airplane turned out to be correct for a brief period.
On November 29, 1945 Pan American World Airways (Pan Am) became the launch customer with the largest commercial aircraft order in history, a $24,500,000 order for 20 Stratocruisers. Earlier in 1945 a Boeing C-97 had flown from Seattle to Washington, D.C. nonstop in six hours and four minutes; with this knowledge, and with Pan Am President Juan Trippe's high regard for Boeing after their success with the Boeing 314 Clipper, Pan Am was confident in ordering the expensive plane.
The 377 shared the distinctive design of the C-97, with a "double-bubble" fuselage cross-section, resembling an inverted figure-8, with 6,600 ft³ (187 m³) of interior space shared between two passenger decks. Outside diameter of the upper lobe was 132 inches, compared to 125 inches for the DC-6 and other Douglas types (and 148 inches for today's 737). The lower deck served as a lounge, seating 14. The 377 had innovations such as higher cabin pressure and air conditioning; the superchargers on the four Pratt & Whitney R-4360 engines increased power at altitude and allowed constant cabin pressure. The wing was the Boeing 117 airfoil, regarded as the "fastest wing of its time". In all, 4,000,000 man-hours went into the engineering of the 377. It was also one of but a few double deck airliners, another being its French contemporary, the Breguet Deux-Ponts, as well as Boeing's own 747 and the Airbus A380. A total of 56 were built, one prototype (later reconditioned) and 55 production aircraft.
First flight of the 377 was on July 8, 1947, two years after the first commercial order. The flight test fleet of three 377s underwent 250,000 mi (217,000 nmi; 402,000 km) of flying to test its limits before certification.
Adoption of the Stratocruiser got a boost from the US government, with a controversial incentive package offered to Northwest Orient Airlines for its purchase. Its components were unusually generous mail contracts offered to Northwest for opening new routes to Hawaii and points in the western Pacific region that they were invited to apply for, and a Reconstruction Finance Corporation loan earmarked for the purchase of a fleet of Stratocruisers. Pan-Am saw Northwest's mail contract deal and appealed for new terms in their own international mail contracts, which were granted much to the consternation of Trans World Airlines, who were able to provide the same Atlantic mail services as Pan-Am with lower operating costs. The Northwest deal led to allegations of graft and political favoritism towards Boeing. The other carriers who adopted the Stratocruiser were British Overseas Airways Corporation, American Overseas Airlines (merged with Pan Am in 1950) and United Airlines. The last 377 was delivered to BOAC in May 1950. On this delivery flight, Boeing engineer Wellwood Beall accompanied the final 377 to England, and returned with news of the de Havilland Comet, the first jet airliner, and its appeal. The tenure of the Stratocruiser with United ended in 1954, when United had the opportunity to sell them to BOAC after finding them unprofitable without the extra mail subsidies enjoyed by Pan Am and Northwest.
As the launch customer, Pan Am was the first to begin scheduled service, from San Francisco to Honolulu in April 1949. At the end of 1949 Pan Am, BOAC and American Overseas Airlines (AOA) were flying 377s transatlantic, while Northwest Orient Airlines was flying in the United States; in January 1950 United began flights from San Francisco to Honolulu. Stratocruisers were pressed into emergency military service following the onset of the Korean War. By late 1950, Northwest Orient was serving New York City, Chicago, Detroit, Minneapolis/St. Paul, Milwaukee, Spokane, Seattle, and Honolulu with the aircraft. By late 1952 Northwest had placed the Stratocruiser in service to Tokyo via Anchorage, Alaska. However, Northwest replaced the Stratocruiser on the Honolulu run in 1953 and by late 1955 had replaced it in their Tokyo service. For a short time Pan Am flew their 377s to Beirut, Lebanon; however, after 1954 no 377 was scheduled east of Europe or west of Singapore. Also in 1954, United was operating nonstop service with the Stratocruiser between Los Angeles and Honolulu and also between Seattle and San Francisco. According to its August 1, 1954 system timeable, United's service between Honolulu and Los Angeles and San Francisco operated with the 377 featured an all first class cabin at this time as well. In 1955 BOAC 377s had 50 First Class seats (fare $400 one way New York to London) or 81 Tourist seats (fare $290). In 1956 Pan Am was flying the 377 from Los Angeles and San Francisco to Sydney with stops at Honolulu, Canton Island and Suva (via Nadi Airport in Fiji). By 1958 Pan Am was operating the Stratocruiser between Seattle and Fairbanks, Juneau and Ketchikan in Alaska and between Seattle and Whitehorse in the Yukon Territory of Canada. Within six years of first delivery, the Stratocruiser had carried 3,199,219 passengers; it had completed 3,597 transcontinental flights, and 27,678 transatlantic crossings, and went between the United States and South America 822 times. In these first six years, the Stratocruiser fleet had flown 169,859,579 miles (273,362,494 km).
The 377 was one of the most advanced and capable of the propeller-driven transports, and among the most luxurious, but it was troubled by reliability issues in critical areas, and related issues with maintenance costs. Problems included catastrophic structural failures of propellers, failures of propeller pitch control leading to overspeed incidents, problems related to the poor thermal design of the engine, and aerodynamic problems arising from design constraints imposed by the engine's thermal problems. Its service record was marred by a high incidence of in-flight emergencies and hull-loss accidents related to those issues. The propellers were the subject of Airworthiness Directives in 1955, 1957, and 1958.
In 1953, "United's Ray Ireland ...described the Stratocruiser as unbeatable in luxury attraction but is uneconomical. Ireland said PAA's Stratocruiser competition to Hawaii induced United to buy the plane originally." In 1950 United's seven 377s averaged $2.46 "direct operating cost" per plane-mile, and "Indirect costs are generally considered to be equal or greater than the direct costs." Most operators at the time were utilizing Stratocruisers on VVIP class long-range routes where higher prices could be charged, off-setting the higher operating costs. The sole exception to this was Northwest Airlines, who managed to keep the aircraft competitive on a series of shorter U.S. domestic routes where the aircraft's higher payload capacity benefited further from lower fuel weights. United however could not integrate their six-plane fleet of 377s. By 1954 the lack of spares and the inability to cross-train their Douglas crews with the type relegated their Stratocruisers primarily to their Hawaii route, where they faced stiff competition from Pan American and Northwest. By the end of that year the six United 377s were all sold to BOAC in a deal carefully orchestrated by Douglas Aircraft. BOAC, which was short of aircraft after the grounding of the Comet 1, paid between US$895,000 and US$995,000 per unit and spares for what were essentially five-year-old aircraft. An equivalent brand new Douglas DC-7 cost US$775,000 in 1954.
Boeing set never-exceed speed at 351 mph (305 kn; 565 km/h) IAS, but in testing, the 377 reached 409 mph (355 kn; 658 km/h) IAS (about 500 mph (430 kn; 800 km/h) TAS) in a 15–20 degree dive at 13,500 ft (4,100 m) Typical airline cruise was less than 300 mph (260 kn; 480 km/h); in August 1953, Pan Am and United 377s (and United DC-6s) were scheduled between Honolulu and San Francisco (2,398 mi (3,859 km)) in 9 h 45 min each way.
The longest (by distance) 377 nonstop flights were made by Pan Am from Tokyo to Honolulu during four winter seasons beginning in 1952–1953. In January 1953, two nonstops a week were scheduled with a flight time of 11 hr 1 min due to strong tailwinds; the following August all flights took 19 hours, with a stop at the Wake Island Airfield.
By 1960, Stratocruisers were being superseded by jets, such as the de Havilland Comet, Boeing 707, and Douglas DC-8. The last flight of the 377 with United was in 1954, the last with BOAC was in 1959, and the last with Northwest was in September 1960. By November 1960 only a weekly Pan Am Honolulu to Singapore flight remained, and the 377 was retired by Pan Am in 1961. High operating costs, owing in large part to the fuel consumption and maintenance requirements of the Wasp Major engines, led to rapid abandonment of the 377 with the onset of the jet era. That stands in contrast to its contemporaries such as the Douglas DC-6 and the Lockheed Constellation, which commonly found new roles on secondary routes or re-purposed as freighters. A few 377s were sold to smaller airlines, used as freighters, or converted by Aero Spacelines into heavily modified enlarged freighters called Guppies. During 1959 and 1960, Transocean Airlines assembled a fleet of fourteen at bargain basement prices. In 1960 TOA went bankrupt and only four were in operable condition. The hulks were stored at Oakland International Airport through the 1960s and cannibalized for parts, contributing some to the Aero Spacelines Guppies. Five remaining 377s were also modified by Bedek Aviation to resemble former U.S. Air Force Model 367 Stratofreighters and pressed into service with the Israeli Defense Force. Two were shot down during the course of their service and the three remaining 377Ms were retired from service in 1978 and subsequently scrapped. None of the original 56 377s built were preserved for display. Currently, the IAI Museum in Israel has a C-97 (4X-FPM) on display painted to resemble their most famous 377M, 'Masada'.
In addition to the Israeli Anaks a company called Aero Spacelines was converting old 377s to aircraft called Guppys in the 1960s. There were three types: the Pregnant Guppy, Super Guppy, and Mini Guppy. They had an extension to the top of the fuselage to enable them to carry large aircraft parts between manufacturing sites.
This aircraft type suffered 13 hull-loss accidents between 1951 and 1970 with a total of 139 fatalities. The worst single accident occurred on April 29, 1952. The aircraft type also experienced a significantly high rate of in-flight emergencies related to engine and propeller failure, resulting in Airworthiness Directives. Faults included structural failures of neoprene-cored propellers, failures of propeller pitch control resulting in overspeed, and failures related to engine cooling. Six propeller failures between 1950 and 1955 resulted in separation or near-separation of engines from mounts, with two resulting in hull-loss accidents. Directives were issued in 1950, 1955, and 1958 regarding enhanced maintenance and fault detection, in-flight vibration monitoring, and propeller replacement. A Directive concerning the pitch control system was issued after the October 16, 1956 hull-loss accident. A June 1957 overspeed incident occurred on Romance of the Skies, after the compliance date of the Directive and less than six months before its fatal accident of November 8, 1957. No hull-loss accidents after the loss of the Romance have been attributed to an overspeed incident.
Data from Airliners of the World
Aircraft of comparable role, configuration and era
The 1954 Prestwick air disaster was the crash, in the early hours of Christmas Day 1954, of Cathay a British Overseas Airways Corporation Boeing 377 Stratocruiser on landing at Prestwick Airport, Scotland; 28 of the 36 on board were killed.A Yank in Ermine
A Yank in Ermine is a 1955 British comedy film directed by Gordon Parry and starring Peter M. Thompson, Noelle Middleton, Harold Lloyd Jr. and Diana Decker, and featuring Jon Pertwee and Sid James. It was adapted by John Paddy Carstairs from his own novel "Solid! Said The Earl". The film includes the song "Honey, You Can't Love Two", sung by Decker and written by Eddie Pola and George Wyle.Aero Spacelines Pregnant Guppy
The Aero Spacelines Pregnant Guppy was a large, wide-bodied cargo aircraft built in the United States and used for ferrying outsized cargo items, most notably NASA's components of the Apollo program. The Pregnant Guppy was the first of the Guppy line of aircraft produced by Aero Spacelines. The design also inspired similar designs such as the jet-powered Airbus Beluga, and the Boeing Dreamlifter.American Overseas Airlines
American Overseas Airlines (AOA) was an airline that operated between the United States and Europe between 1945 and 1950. It was headquartered in Midtown Manhattan, New York City.Boeing 367
Boeing 367 was a model number for aircraft within the Boeing Company and refers to two different aircraft:
Boeing 367/C-97 Stratofreighter was a B-29 based prototype for the Boeing 377 Stratocruiser aircraft.
Boeing 367-80 or 'Dash 80', the 1950s prototype of Boeing's first jet airliner which had evolved from the original 367 design through a large number of design studies.Boeing C-97 Stratofreighter
The Boeing C-97 Stratofreighter was a long-range heavy military cargo aircraft developed from the B-29 and B-50 bombers. Design work began in 1942, the first of 3 prototype XC-97s flew on 9 November 1944 (none saw combat), and the first of 6 service-test YC-97s flew on 11 March 1947. All these (9) were based on the 24ST alloy structure and Wright R-3350 engines of the B-29 but with a larger-diameter fuselage upper lobe (making a figure of eight or 'double-bubble'section) and they had the B-29 vertical tail with the gunners position blanked off. The first of 3 heavily revised YC-97A incorporating the re-engineered wing ( higher strength 75ST alloy), taller vertical tail and larger Pratt and Whitney R-4360 engines of the B-50 bomber, flew on 28 January 1948 and was the basis of the subsequent sole YC-97B, all production C-97s, KC-97s and civilian Stratocruiser aircraft . Between 1944 and 1958, 888 C-97s in several versions were built, 811 being KC-97 tankers. C-97s served in the Berlin Airlift, the Korean War, and the Vietnam War. Some aircraft served as flying command posts for the Strategic Air Command, while others were modified for use in Aerospace Rescue and Recovery Squadrons (ARRS).Consolidated R2Y
The Consolidated R2Y "Liberator Liner" (Consolidated Model 39) was an airliner derivative of the B-24 Liberator built for the United States Navy by Consolidated Aircraft.Double-deck aircraft
A double-deck aircraft has two decks for passengers; the second deck may be only a partial deck, and may be above or below the main deck. Most commercial aircraft have one passenger deck and one cargo deck for luggage and ULD containers, but only a few have two decks for passengers, typically above a third deck for cargo.Flight 202
Flight 202 may refer to:
Pan Am Flight 202, a Boeing 377 Stratocruiser which crashed in the Amazon Basin on 28 April 1952
Ariana Afghan Airlines Flight 202, a Douglas DC-4 which crashed in Lebanon on 21 November 1959
Airblue Flight 202, an Airbus A321 which crashed in Pakistan on 28 July 2010
Emirates Flight 202, onboard which the man responsible for the 2010 Times Square car bombing attempt attempted, but failed, to leave the United States. He was arrested moments before the aircraft left the gate at John F. Kennedy International AirportFlight 7
Flight 7 or Flight 007 may refer to:
Korean Air Lines Flight 007, a 1983 incident in which a Korean Air Lines Boeing 747 was shot down over the Sea of Japan
Pan Am Flight 7, a 1957 crash of a Pan Am Boeing 377 Stratocruiser 10-29
Western Air Express Flight 7, a 1937 crash of a Western Air Express Boeing 247B
Air France Flight 007, a 1962 crash of an Air France Boeing 707
LOT Polish Airlines Flight 7, a 1980 crash of a LOT Polish Airlines Ilyushin Il-62Northwest Orient Airlines Flight 2
Northwest Orient Airlines Flight 2 was a Boeing 377 Stratocruiser aircraft that was ditched into Puget Sound just off Maury Island at the Point Robinson Light shortly after takeoff from the Seattle-Tacoma International Airport (Sea-Tac) on April 2, 1956. The plane flew over Normandy Park heading west-southwest. All of those aboard survived the ditching and escaped the aircraft before it sank, but four passengers and one flight attendant subsequently died.On Mark Engineering
On Mark Engineering was an American aircraft remanufacturing company established in 1954 at Van Nuys Airport in California. Its most significant products were rebuilding military surplus A-26 Invaders into executive transports—the Marketeer with an unpressurized fuselage and the Marksman with fuselage pressurization. On Mark converted 41 Douglas B-26s into one YB-26K and 40 B-26K Counter-Invaders (later redesignated A-26A) for counterinsurgency missions with the US Air Force. On Mark also undertook conversion work of a Boeing 377 Stratocruiser into the prototype Pregnant Guppy for Aero Spacelines.Pan Am Flight 202
Pan American World Airways Flight 202 was a Boeing 377 Stratocruiser aircraft that crashed in the Amazon Basin about 281 nautical miles (520 km) southwest of Carolina, Brazil on April 29, 1952. The accident happened en route from Rio de Janeiro, Brazil, to Port of Spain, Trinidad and Tobago, during the third leg of a four-leg journey. All 50 people on board were killed in the worst-ever accident involving the Boeing 377.The investigation took place under exceptionally unfavorable conditions, and the exact cause of the crash was not established. However, the Stratocruiser's engines were known to be temperamental, and it was theorized that an engine had separated in flight after propeller blade failure.Pan Am Flight 6
Pan Am Flight 6 (registration N90943, and sometimes erroneously called Flight 943) was an around-the-world airline flight that ditched in the Pacific Ocean on October 16, 1956, after two of its four engines failed. Flight 6 left Philadelphia as a DC-6B and flew eastward to Europe and Asia on a planned multi-stop trip. On the evening of October 15, 1956, the flight left Honolulu on a Boeing 377 Stratocruiser Clipper named Sovereign Of The Skies (Pan Am fleet number 943, registered N90943). The accident was the basis for the 1958 film Crash Landing.Pan Am Flight 7
Pan Am Flight 7 was a westbound around-the-world flight originating in San Francisco that crashed in the Pacific Ocean on November 8, 1957, while flying to Honolulu, Hawaii. The aircraft assigned to the flight was a Boeing 377 Stratocruiser named Romance Of The Skies, and the crash killed all 36 passengers and 8 crew members. No radio reports of any emergencies were ever received from the crew of the flight, and the fate of the flight was not known until about nine hours after its last known radio transmission, when the plane, if it had still been flying, would have exhausted its fuel. Under the assumption that the plane could have survived a controlled landing on the ocean surface, the United States Coast Guard launched a massive search for the plane and any potential survivors. The week-long hunt became the largest search and rescue operation in the Pacific Ocean at the time. The bodies of 19 of the victims and pieces of the plane were eventually recovered from the ocean about 900 miles (1,400 km) northeast of Honolulu.
Multiple investigations into the cause of the crash were inconclusive. Despite some theories that the plane may have been the victim of sabotage, poor maintenance, or in-flight fire, investigators could not find enough evidence to support any definite conclusion. The final report from the Civil Aeronautics Board (CAB), who conducted the investigation, stated, "The Board has insufficient tangible evidence at this time to determine the cause of the accident."Pan Am Flight 845/26
Pan Am Flight 845/26 was a four-engined Boeing 377 Stratocruiser named Clipper United States and registered as N1032V. It departed Portland International Airport in Oregon on a flight to Honolulu International Airport in Hawaii on March 26, 1955. The aircraft was en route and about 35 miles (56 km) off the Oregon coast when at 11:12 Pacific Standard Time the No. 3 engine and propeller tore loose from the wing causing a loss of control. The aircraft was ditched.
The aircraft floated for twenty minutes before sinking in 1,600 metres (5,200 ft) of water. Approximately two hours after the aircraft ditched, the United States Navy attack transport USS Bayfield (APA-33) arrived on the scene and rescued the 19 survivors. Four people died.The probable cause was failure of No. 3 propeller which caused the engine to detach and the aircraft to become uncontrollable.
The experience provided lessons that helped prevent any casualties in another ditching the following year, when Pan Am Flight 6 sank between Honolulu and San Francisco.Propliner
A propliner is a large, propeller-driven airliner. Typically, the term is used for piston engine airliners that flew before the beginning of the jet age, not for modern turboprop airliners. With the notable exception of the de Havilland Albatross of the 1930s, which was largely fabricated of wood, propliners featured all-metal wings and structural members, retractable landing gear, and generally two or four engines.
The first propliner was the Boeing 247 (first flight 1933), with the Douglas DC-1 and Douglas DC-2 closely following in response. The most successful is the Douglas DC-3, which was produced in the thousands, and is still in widespread use; while the Dewoitine D.338 and SNCASE SE.161 Languedoc were developed in France and Germany produced the Focke-Wulf Fw 200 Condor and Junkers Ju 90. In Japan a license-built version of the Douglas DC-3 was developed as the Nakajima L2D and the smaller Mitsubishi MC-20 was locally developed. In the Netherlands Fokker, previously one of the leading manufacturers of airliners before the Boeing 247 appeared, became the European sales agent for Douglas DC-2s and DC-3s. Most British-built aircraft of the period were less advanced, such as the Avro 642 Eighteen and de Havilland Express; one exception was the Armstrong Whitworth Ensign. Other American-designed propliners included the Douglas DC-4, Douglas DC-5 and Martin 2-0-2. None of these models featured cabin pressurization.
With the earlier introduction of the Boeing 307 Stratoliner and the experimental Douglas DC-4E, a second generation of propliners emerged. These technologically more modern aircraft featured cabin pressurization systems allowing greater comfort by allowing aircraft to fly higher and above much of the lower altitude weather, although it was not until the Lockheed Constellation, followed by the Douglas DC-6 and Douglas DC-7, that this design advance became common.
By the 1950s the traveling public were increasingly finding themselves being transported upon long range pressurized propliners such as the Boeing 377 Stratocruiser, Lockheed L-1049 Super Constellation and Lockheed L-1649 Starliner, or shorter ranged twin engined Martin 4-0-4 and Convair CV-240, CV-340 and CV-440 aircraft. British propliners included the Airspeed Ambassador, Vickers Viking and Handley Page Hermes, while the Canadair North Star (a development of the Douglas DC-4) was produced in Canada. The Breguet Deux-Ponts and Hurel-Dubois HD.31 were manufactured in France; and the Soviet Union produced the postwar twin-engined Ilyushin Il-12 and Ilyushin Il-14, both produced in quantity through the 1950s. Finally, the Swedish SAAB Scandia was produced in small numbers.Transocean Air Lines
Transocean Air Lines was an Oakland, California-based airline that operated from 1946 until 1960. The Transocean name was also used in 1989 by another US-based air carrier, TransOcean Airways, which previously operated as Gulf Air Transport.
Boeing aircraft model numbers