Aero Spacelines B-377MG Mini Guppy
Four-engined Heavy Lift Commercial Transport

Archive Photos 1,2

1949 Aero Spacelines B-377MG Mini Guppy (N422AU, s/n 15937) 1

Overview 3

Aero Spacelines Inc., Subsidiary of Unexcelled Inc., developed two conversions of Boeing Stratocruiser/C-97 transport aircraft, under the names of Pregnant Guppy and Super Guppy respectively, to provide specialized transportation of large booster stages and other items used in America’s national space programs. The conversions were performed entirely with private capital and with no prior contracts or other commitments. The U.S. government subsequently contracted for the exclusive use of both aircraft, and heavy utilization by NASA and the Department of Defense has precluded their use for commercial transportation of outsize cargoes.

To meet a potential commercial requirement, Aero Spacelines subsequently built a prototype of a third Stratocruiser conversion, known as the Mini Guppy. A fleet of ten to twelve new Guppy aircraft for the commercial market are programd for completion by 1972, utilizing the company’s basic inventory of B-377 Stratocruiser airframes and certain other large fuselages.

The new aircraft will include a commercial version of the Super Guppy with a floor width of 13 ft 0 in (3.96 m), a diameter of 25 ft 6 in (7.77 m) and a cruising speed of 300 mph (483 kph), carrying a 50,000 pound (22,680 kg) payload; and further Mini Guppy’s power by turboprop engines to increase payload to 60,000 pounds (27,215 kg).

Aero Spacelines’ parent company, Unexcelled, Inc., of New York, formed a new company, early in 1968, known as Tex Johnson, Inc., to produce Total Inflight Simulation (TIFS) trainers. TIFS are variable-stability aircraft designed to train aircrews by computerized simulation of the control response characteristics of any given aircraft. The first TIFS aircraft, based on a Convair Model 580, will be used as a Boeing 707 trainer, with certification expected in June 1969.

Aero Spacelines B-377MG Mini Guppy 3

Following purchase of the company by Unexcelled Inc., in 1965, Aero Spacelines moved its main offices and base of operations from Van Nuys to Santa Barbara, California. There it developed the first of several large aircraft intended to satisfy a rapidly developing commercial market for the airlift of large aircraft sections, helicopters, jet-engine power plants, oil drilling equipment and other cargoes too large to be accommodated by any existing commercial aircraft.

The first aircraft, known as the B-377MG Mini Guppy utilizes a basic B-377 fuselage, lengthened by 22 ft 6 in (6.86 m). It has a new wing center-section, increasing the span by 15 ft 0 in (4.57 m), and a floor width of 13 ft 0 in (3.96 m), the widest of any existing U.S. aircraft. It has it been expanded laterally, to accommodate cargo up to 18 ft 2 in (5.54 m) in width and 15 ft 5 in (4.7 m) in height. Loading is affected by means of a swing tail.

The modification was started in December 1966 and completed in May 1967. The aircraft made its maiden flight on 24 May and, just two days in 19 hours later, flew to Paris for display at the 1967 Paris Air Show.

Specifications (B-377MG) 3


Dimensions, external

Dimensions, internal (Cargo Compartment




  1. Shupek, John. Photos by John Shupek copyright © 2004 Skytamer Images. All Rights Reserved
  2. Shupek, John. 3-view drawing by John Shupek, copyright © 2013 Skytamer Images. All Rights Reserved
  3. Taylor, John and W.R. Leonard, Jane’s All The World’s Aircraft 1968-69. McGraw-Hill Book Company, 1968


Skytamer Images (
Est. 1998