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The Guppy – Ugliest Aircraft Ever?

The Pregnant Guppy and the Super Guppy were cargo planes designed to carry oversized objects for NASA’s Apollo Saturn program that ran for the best part of the 1960s.

The product of an ambitious financial gamble by multimillionaire entrepreneur John M. Conroy, once in action the Guppy series singlehanded saved NASA months of delays by guaranteeing that rocket segments and other mammoth hardware were delivered in a timely manner.

The Guppy’s key involvement in the transportation of Apollo components also ensured that President John F. Kennedy’s 1962 pledge to walk on the moon by the decade’s end was fully realized.

A Super Guppy parked on a runway from the side.
The later Super Guppy. Photo credit – MilborneOne CC BY-SA 3.0.


Logistical Nightmare

During the Apollo Saturn program NASA administrators were becoming increasingly anxious about the delivery of upper-stage rocket segments carried out by seagoing barges and transports.

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In contrast to the lower stage components of the Saturn I and Saturn IB, which had arrived relatively troublesome-free from nearby Huntsville and Michoud with the assistance of helicopters, getting the upper stage components to Cape Canaveral in Florida by boat was a logistical nightmare, involving an arduous journey down the Pacific Coast, through the Panama Canal and across the Gulf of Mexico to the final destination.

NASA was principally concerned that these challenging voyages, rife with bad weather and unexpected obstacles, were delaying the arrival of crucial parts.

Apollo 11 parts being loaded into a Super Guppy.
Apollo 11 parts being loaded into a Super Guppy.

Furthermore, another worry was their over-reliance on the Panama Canal which, if closed for any reason, would mean cargo ships would have to sail around South America, almost definitely causing the carefully calculated launch schedules of the program to collapse.

In response, NASA employees and contractors came up with a variety of alternatives. Among the most unusual of their proposals involved a transcontinental blimp that would dangle the machinery underneath, and the use of a pre-war dirigible craft was also seriously considered.

One of the brainstormers was John M. Conroy, CEO of Aero Spacelines Incorporated, who suggested that his fleet of over a dozen four-engined Boeing B-377 Stratocruisers could be modified into a bloated cargo aeroplane.

Although his idea was largely dismissed by engineers and aerodynamicists, who believed that no aeroplane could possibly haul a rocket segment and still be able to fly, Conroy remained convinced he had the solution – and he was even prepared to dip into his own pockets to make it a reality.

The Stratocruiser was going to be modified to haul large cargo.
The ideas was for the Stratocruiser to be modified to haul large cargo.

The Pregnant Guppy

A dashing and charming multimillionaire, during a presentation to NASA at the Marshall Space Flight Center (MSFC) Conroy managed to persuade the MSFC director Dr Werher Von Braun and a few other executives that his idea was feasible.

However, although they had been receptive, Conroy’s proposal was almost immediately derailed when NASA and MSFC stated they couldn’t allocate substantial funds to it. As a result, Conroy took matters into his own hands, spending 1 million dollars of his own money on the modification of a single Boeing Stratocruiser.

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The resulting B-377 Pregnant Guppy had, with the addition of the cabin section of another Stratocruiser, a significantly extended fuselage that could accommodate a single rocket segment. In a self-contained transportation system, the cargo was loaded and unloaded with the help of a section of the fuselage, just aft of the wing’s trailing edge, that could be separated to provide an entryway into the hold.

The 377 was dervied from the B-29.
The 377 was dervied from the B-29 and evidence of this can be seen in the Pregnant Guppy.

However, by the time the Pregnant Guppy had completed its maiden voyage on September 19th 1962, Conroy was seriously over his budget and desperately in need of a fresh injection of cash. As a result on September 20th, after getting special permission from the Federal Aviation Administration (FAA), Conroy and his crew set off east from the Aero Spacelines facility at Van Nuys, California, on a demonstration tour intended to drum up interest for his invention.

Following a series of interim stops, the Pregnant Guppy landed at the Marshall Space Flight Center in Huntington, Alabama where Conroy intended to illustrate to the NASA top brass the heavy-loading capabilities of his brainchild.

Using a combination of sandbags and extra fuel to simulate the weight of a Saturn rocket segment, Conroy took off from the runway with a pair of MSFC observers, Julian Hamilton and Herman Kroeger, on board to examine proceedings.

The Pregnant Guppy was not a looker.
Enter the Pregnant Guppy – a heavily modified 377. The looks were certainly unusual…

Conroy showed both of his passengers that even with 2 of the 4 engines running he could still maintain course and altitude with only light control, a feat that so impressed Kroeger he lapsed into German in excitement when reporting his experience to Von Braun after touchdown. 

Having proven that his aeroplane was flightworthy, on July 10th 1963 with NASA officials anxious about the timely delivery of the S-IV stage of the Saturn, the Pregnant Guppy was finally issued an airworthiness certificate.

The plane was immediately made operational, and after transferring various pieces of Apollo hardware in the summer months, the Pregnant Guppy successfully transported the S-IV stage to Cape Canaveral on January 29th 1964. In doing so the Guppy had saved up to three weeks in transit time and reduced transportation costs significantly to the delight of NASA officials, who inundated Conroy with much-desired endorsements and long-term contracts.

On the other hand with the transportation of the even larger S-IVB stage looming on the horizon, the astute Conroy was quick to propose a second generation that would be even bigger and more powerful than the Pregnant Guppy.

The Saturn IV being loaded into a Guppy.
Loading S-IV stage into the “Pregnant Guppy” – this aircraft was built to carry these oversized loads.

The Super Guppy

In fact even before he had signed the first NASA contract, Conroy had already written to Von Braun suggesting a jumbo version, arguing that in addition to the S-IVB stage that it could also lug the enormous instrument units for both the Saturn IB and the Saturn V, deliver the cyclopean Apollo lunar module adapter unit, and act as a back-up to the Pregnant Guppy.

Once again Conroy used his own resources to develop the new aircraft, but he was also assisted by MSFC personnel and a flight test expert from NASA’s Flight Research Center at Edwards Air Force Base.

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Originally dubbed the B-377 VPG, which stood for ‘Very Pregnant Guppy,’ the name was eventually changed to the B-377 Super Guppy, a Frankenstein-like plane whose cockpit, forward fuselage, and wing sections had been ripped from a Stratocruiser and its 4 Pratt & Whitney T34-P-7WA engines scavenged from a Boeing C-97J, the Air Transport version of the commercial Stratocruiser.

The Super Guppy was even large in almost all dimensions.
The Super Guppy took size up a notch. Photo credit – Bill Larkins CC BY-SA 2.0.

Dimensionally it was bigger than the Pregnant Guppy, having a wingspan increased by 4.57 meters, a fuselage lengthened by 9.40 meters and an upper fuselage that housed cylindrical loads with a diameter of 7.62 meters.

Other improvements included better cockpit pressurization, enabling it to cruise at a speed of 285 miles per hour and to soar at altitudes as high as 25,000 feet to avoid bad weather, and also a reworked empennage that featured a vertical fin, larger dorsal tips, and a 48-inch extension to the horizontal stabilizer tips for better in-flight stability.

Building on the lessons of its predecessor, the Super Guppy also featured a markedly better loading procedure in which cargo was inserted from the front with the aid of a pivotable forward section of the fuselage.

Moreover, taking lessons from Pregnant Guppy missions of the past, the ground support techniques and equipment needed for this process, such as the cargo lift trailer which employed the scissor-lift principle to raise its load into the interior of the cargo bay, were also made considerably more efficient.

The Super Guppy on landing.
Whilst ugly, it is certainly function over form. The Guppy was an excellent transport aircraft.

After flying for the first time on August 31st 1965, by the spring of 1966 the Super Guppy was awarded FAA approval and almost immediately called upon by NASA to shift heavy spacecraft components. With much aplomb, the Super Guppy had soon completed its first assignment; hauling a Saturn instrumentation unit created by IBM from Huntsville to the Douglas Aircraft Corporation’s plant at Huntington Beach for systems testing.

Along the way, however, there were a few mishaps. On September 25th 1965 for example, while manoeuvring the Super Guppy into a high-speed dive for FAA authentication, a mid-air collision caused the nose to explode, nearly crashing the craft.

In another more humorous episode from 1966, the crew of one Super Guppy, who was forced to re-divert after a spell of bad weather on their way out of Los Angeles, found themselves surrounded by armed policemen from Strategic Air Command (SAC) and questioned for hours after failing to notify the SAC base they were landing.

The sucessor to the Super Guppy is the Airbus Beluga. Whilst sharing no components, the design philosophy can be seen.
The successor to the Super Guppy is the Airbus Beluga. Whilst sharing no components, the design philosophy can be seen. Although the Super Guppy is still in service with NASA. Photo credit – Don-vip CC BY-SA 3.0.

Nevertheless, despite some unfortunate incidents, over the next few years, the Super Guppy would be instrumental in the success of several NASA operations. In 1968 it would transport the special environmental chamber used in the final preparations of the Apollo mission that would put a man on the moon, and in the late 1960s and early 1970s Guppies would ferry devices such as the multiple docking adaptor, the Apollo telescope mount, and the Skylab workshop.

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As such, it wouldn’t be unreasonable to say that both the Pregnant Guppy and the Super Guppy played an integral role in the 1969 moon landing and in America’s triumph over the Soviet Union in the Space Race.

How many Supеr Guppy Airplanеs arе thеrе?

Thеrе arе four Supеr Guppy airplanеs in еxistеncе. Thеsе massivе planеs, built by NASA and Airbus, arе crucial for moving ovеrsizеd cargo that won’t fit in other aircraft. Thеir uniquе dеsign and spacious cargo bays makе thеm vital in transporting largе componеnts for spacе missions. Additionally, they also transport government projects, and military еquipmеnt across continеnts.


  • Crew: 4
  • Length: 143 ft 10 in (43.84 m)
  • Wingspan: 156 ft 3 in (47.63 m)
  • Height: 48 ft 6 in (14.78 m)
  • Cargo bay dimensions: 111 ft × 25 ft × 25 ft (33.83 m × 7.62 m × 7.62 m)
  • Empty weight: 101,500 lb (46,040 kg)
  • Max takeoff weight: 170,000 lb (77,111 kg)
  • Powerplant: 4 × Allison 501-D22C turboprop engines, 4,680 shp (3,490 kW) each
  • Maximum speed: 250 kn (290 mph, 460 km/h)
  • Range: 1,734 nmi (1,995 mi, 3,211 km)
  • Service ceiling: 25,000 ft (7,600 m) certified