Profile – From Stratofreighter to Guppy

Meanwhile, at the same time as surplus C-97s and Stratocruisers were coming onto the market, the National Aeronautics and Space Administration (NASA) found itself faced with a major logistics problem involving the need to transport giant S-11 rocket stages of the Saturn V rocket launcher for the Apollo space programme. These had to be moved from the manufacturer’s factory on the west coast by special barges through the Panama Canal to NASA’s base at Cape Kennedy in Florida. The sheer size of the load precluded transportation by road or rail.

At Aero Spacelines Inc. , Mansdorf was aware of the problem and came forward with the suggestion of converting one of his Stratocruisers by enlarging its fuselage to a size whereby it could transport such outsized cargoes. Jack Conroy was enthusiastic about the idea and he became the chief promoter and main driving force behind the scheme. Thus, a new branch in the Stratocruiser/Stratofreighter family tree – the Guppy family of conversions.

Work began on the first aircraft in December 1961, at Van Nuys airport, California, where On Mark Engineering Co was contracted to carry out the conversion. First, an extra 16ft Sin (5. 08m) section was inserted into the fuselage behind the wings. Next was built a gigantic upper fuselage, 20ft 4in (6. 2m) in diameter, large enough to house rocket stages up to a diameter of 19ft 9in (6. 02m) to be loaded through the split rear fuselage which was unbolted aft of the wing and swung back out of the way. Although some sceptics doubted that such a bulgy aircraft could actually fly, the final conversion first flew on September 19, 1962, and handled surprisingly well. The plane became officially designated B-377PG, the last two letters standing for “Pregnant Guppy” which it had been named. It was allocated the registration number N1024B. Because of the Pregnant Guppy’s success, by mid-1963 Aero Spacelines received a contract from NASA for the transportation of equipment and components for the space programme.

NASA soon wanted a much larger version of the machine to deliver by air the huge S-IVB second stage of the Saturn V rocket. To solve this and other transportation problems, the company began developing a bigger conversion. Called at first the 377VPG, Very Pregnant Guppy, it later became known as the 377SG Super Guppy. To begin, the last surviving YC-97J was purchased. This aircraft, No 52-2693, was one of two specially converted C-97’s used by MATS (Military Air Transport Service) to flight test early turboprop engines, the other, No 52-2762, having suffered a collapsed nosewheel and cannibalisation for spare parts at Norton AFB, California.

Reconstruction began late in 1964. The fuselage was extended by 30ft 10in (9. 4m), a newly designed tail was built and the wingspan was increased to 156ft 3in (47. 63m). Whereas the Pregnant Guppy had loaded its cargo by removing the entire tail section, the Super Guppy featured a hinged nose which allowed the cargo to be loaded through the front into a cavernous 25ft (7. 62m) diameter fuselage compartment. In August, 1965, even though the aircraft was nearing completion, Aero Spacelines was facing severe financial difficulties and during the month a New York conglomerate, Unexcelled Corporation, purchased the company. A few days later on August 31, the Super Guppy made its maiden flight from Van Nuys airport. Several months of flight testing and evaluation followed after which, having been allocated the registration N1038V, the Super Guppy joined its sister ship, the Pregnant Guppy in contract service for NASA in March, 1966.

Later in the year Jack Conroy, who still held his position as president, moved Aero Spacelines Inc to Santa Barbara and, foreseeing a commercial use for an aircraft adapted to carry a large variety of more common outsized cargo such as oil drilling equipment, large computers etc. , he launched the Mini Guppy development programme. The parent aircraft selected was a Boeing Stratocruiser which retained its Pratt & Whitney R4360 piston engines. The Mini Guppy made use of a hinged swinging tail for loading and had an internal fuselage diameter of 18ft 2in (5. 54m). It first flew on May 24, 1967. Allocated the registration N1037V, it was the first Guppy to receive full FAA certification clearing its way for contract use in the commercial aviation market.

A few months later, following the completion of the Mini Guppy programme, Jack Conroy left Aero Spacelines and formed a separate company of his own, Conroy Aircraft Corporation, with which he intended to specialise in special development and conversion of existing aircraft.

Meanwhile, Aero Spacelines embarked on an ambitious expansion programme constructing modern new facilities on Santa Barbara airport and turning its production efforts towards designing and building a new computerised Flight Simulator (TIFS) for the training of pilots for the new wide bodied jets and supersonic transports. Unfortunately, the project was not successful and it was terminated in December, 1969, so that by the beginning of 1970 the company’s future looked bleak because its only income came from NASA contracts for use of the Pregnant Guppy and Super Guppy plus a few minor commercial contracts for the Mini Guppy.

All efforts were now redirected towards a new Guppy programme and the first to be produced under this new scheme was the Mini Guppy Turbine (MGT)-101. This aircraft was similar in size to the first Mini Guppy but was powered instead by four 4,912hp (3663kW) Allison 501-D22C turboprop engines. Because of this increased power it was estimated that it would be able to carry almost twice the payload of the previous machine and it featured for the first time a power-operated swing nose for the quick loading of large parts. It flew for the first time on March 13, 1970 and was allocated the registration N111AS but was lost through a tragic accident at Edwards AFB only two months later on May 12, during its flight test programme.

European Interest

Back in 1967, the Mini Guppy had visited the Paris Air Show and afterwards it had gone on to Toulouse for demonstration to officials at Aerospatiale. At the time they were looking at methods of transporting large sub-assemblies and sections of their projected wide bodied A300 Airbus medium haul transport aircraft from England and various manufacturing sites in Europe to Toulouse for final assembly. The Mini Guppy was not exactly what they wanted but the demonstration stirred their interest towards the next aircraft under construction, an updated version of the Super Guppy.

The intention had been for this new plane, the B-377SGT Super Guppy Turbine-201, to remain with Aero Spacelines so that it could be contracted out to service companies such as Douglas, Convair and Lockheed for the transportation of major sections of the DC01 O and L-1011 TriStar but continuing financial difficulties obliged the company to sell it to the European group. It flew for the first time on August 24, 1970 and it was flight-tested by the company and the FAA for a year before receiving its FM certification on August 26, 1971. Its registration number was N211AS.

Powered by four 4,912hp (3663kW) Allison 501-D22C turboprop engines, the new Super Guppy’s maximum speed was stated as Mach 0. 413 ASI above 14,800ft (4510m) and its maximum cruising speed was 288mph (463km/h). At the same altitude, the plane’s most economical cruising speed was 253mph (407km/h). Its initial climb rate was 1,500 feet per minute (7. 6m/sec) and it had a certificated service ceiling of 25,000ft (7620m). Maximum range was 2,920 miles (4700km) but when fully loaded and with 45 minutes reserve fuel its range shrank to 505 miles (813km). When loading, six large diameter bolts were unfastened and the whole cockpit section, including the nosewheel, could be swung aside on a huge hinge 110° to the left for easy access to the cavernous cargo compartment with its usable volume of 39,000 cubic feet (1104. 4 cubic metres).

The aircraft was delivered to Aerospatiale in November, 1971, as F-BTGV to be headquartered in Paris with Airbus lndustrie as ‘Airbus Skylink 1’. Airbus Industrie had been formed as a multinational company for the purpose of designing and making a European aircraft able to vie successfully for markets in competition with American manufacturers. Members of the Airbus lndustrie consortium then included Aerospatiale of France, CASA of Spain, Messerschmitt-Bolkow-Blohm, VFWFokker of West Germany and Holland and Hawker Siddeley of England. The prototype A300B Airbus had its maiden flight on October 28, 1972 and the type received Franco-German certification on March 15, 1973, FAA certification on May 30, 1974 and entered service with Air France on the Paris/London run on May 23, 1974.

Meanwhile, construction of a second Super Guppy-201 had been well under way in 1970 but work on it had been suspended to concentrate all effort and facilities on the quest for the successful certification of the first machine. After August, 1971 attention refocused on this aircraft and it was flown for the first time a year later on August 24, 1972. Another year passed before it too went to Aerospatiale in August, 1973, as F-BPPA and became ‘Airbus Skylink 2’ with Airbus lndustrie.

In spite of these two successful sales, financial problems continued to plague Aero Spacelines and in 1974 the company nearly closed down. That year, as part of the disposal of assets, both the Pregnant Guppy and the Mini Guppy were sold to American Jet Industries but it took until 1979 to sell the original Super Guppy to NASA. The few years after 1974 were bleak but things very gradually improved. At a meeting during the autumn of 1977 a previously taken decision to terminate Aero Spacelines completely was reversed and a market evaluation showed that there was a potential need for two more Super Guppy aircraft at Airbus lndustrie because of the outstanding success of the A300/ A310 Airbus programme. However, the now much smaller Aero Spacelines did not have the capacity to produce two new Guppy- 201’s within the time required by the European consortium so it was decided to draw up a licencing agreement whereby Aero Spacelines, for a fee, allowed Airbus lndustrie to have the planes built in Europe. Airbus lndustrie in turn drew up a contract with UTA Industries in Paris for the project with the proviso that 50% of the work, mainly involving modifications of the cockpit, wings, nacelles and empennage, would be sub-contracted to the American parent company. Aero Spacelines, later Tractor Aviation, was on the road to recovery once more.

The third Super Guppy-201 flew on July 1, 1982 and was delivered to Airbus lndustrie as F-GDSG where it became ‘Airbus Skylink 3’. The fourth machine, F-GEAI ‘Airbus Skylink 4’, flew for the first time on June 21, 1983 and at the time of writing all four aircraft were being kept busy flying A300, A310 and A320 parts around Europe with the prospect of continued work hauling for the A330/340 and ATR 42 programmes.

A Guppy Stepsister?

As already noted, when he left, Jack Conroy, who had been responsible for the development of the Pregnant Guppy and its successors for Aero Spacelines, founded the Conroy Aircraft Corporation with which he continued to specialise in the modific ation and conversion of existing aircraft. Among his unique creations were the Conroy/Douglas Turbo Three, a DC-3 powered by two 1,600hp (1193kW) Rolls Royce Dart turboprops each driving a Rotol four blade propeller; a turboprop conversion for the Cessna Model 337 Super Skymaster; and another turboprop conversion of a Grumman HU-16 Albatros amphibian.

His second major project was the ‘guppification’ of a Canadair CL-44 into a large-capacity long-range freighter. For this the upper half of the plane’s fuselage was removed and replaced by a new pressurised bulging structure which provided a maximum internal height of 14ft 11 in (4. 24m) almost doubling the volume of the cargo compartment. The converted plane, N447T, was designated Conroy/Canadair CL-44-0 and flew for the first time on November 26, 1969. It was a unique, one-off machine and it was first used by Transmeridian Air Cargo. Later is was flown by Stansted Skyline until the company’s financial collapse after which it was acquired by Heavy Lift Cargo Airlines at Southend, England in mid-1982. After overhaul, it was re-registered EI-BND and has since been mainly used for shifting outsized general cargo. The CL-44-0 Guppy’s most fragile consignment has been a load of giraffes and antelope transported from Mombasa to Newburgh/Stewart, New York, where all animals arrived safe and well.

She is a worthy stepsister to the Guppy Family.

In the nineteen forties when Boeing launched the initial Stratofreighter project they obviously would have been amazed to realise that their aircraft would, nearly a half-century later, be the transportation backbone for what is nowadays their single largest commercial competitor.