Aero Spacelines Mini Guppy
The Aero Spacelines Mini Guppy was the smallest of the three Guppy outsize-cargo airliners derived from the Boeing 377 Stratocruiser. Three airframes were built between 1967 and 1970. The Mini Guppy filled a niche between the larger Super Guppy (which was sized for Saturn S-IVB rocket stages) and the smaller Pregnant Guppy (the original 1962 conversion built for Saturn S-IV stages). All three Mini Guppys are retired; one is preserved at the Tillamook Air Museum in Oregon.
Aero Spacelines founder Jack M. Conroy designed the Mini Guppy as a less-extreme conversion than the Super Guppy. The original Stratocruiser fuselage was cut at floor-level and a new 18-ft-diameter (5.49 m) upper bubble built above. Cargo loading came from a swing-tail arrangement — the entire empennage hinged sideways to expose the hold from the rear — instead of the swing-nose used on the Super Guppy. The result was a 23-tonne payload aircraft with a hold 33 m long but only 5.5 m diameter, well-suited to airliner fuselage components and oil-industry pressure vessels but too small for the Saturn-class rocket stages the Super Guppy was built for.
The Mini Guppy first flew on 24 May 1967. The original variant (one airframe) used four Pratt & Whitney R-4360 Wasp Major radials; the two follow-ons (Mini Guppy Turbine, MGT) replaced these with four Allison 501-D22C turboprops, the same engine type as the Super Guppy Turbine. Operating economics were difficult — the Mini Guppy was too small for many outsize-cargo loads and too large for general freight — and Aero Spacelines went bankrupt in the mid-1970s. The aircraft passed through Aero Union, Erickson Aviation, and American Jet Industries before retirement in 1995.
The Mini Guppy never matched the Super Guppy's longevity. Its niche was eaten on the small end by conventional freighters (DC-6 and 707-200F) and on the large end by the Super Guppy itself; neither end could be retained profitably without high-volume captive customers like the Apollo programme provided. The surviving Mini Guppy at Tillamook (N111AS) is in good external condition; the other two airframes were scrapped after retirement.
For Kids — a shorter, friendlier version
The Mini Guppy was a very special cargo plane. It had a huge, round top that made it look like a big fish. It was built by a company called Aero Spacelines, and the first one flew on May 24, 1967.
The plane started life as a Boeing 377 Stratocruiser. Workers cut the top of the fuselage and added a giant round bubble on top. The new cargo hold was about 18 feet across — wider than a school bus is long!
Loading cargo was done in a cool way. The whole tail of the plane could swing to one side. This opened up the back so workers could slide long items straight in. The hold could carry things like airplane parts and large pressure tanks.
The Mini Guppy was the smallest of three Guppy planes. The bigger Super Guppy carried giant rocket parts for NASA. The Mini Guppy was too small for those, but it was great for other bulky cargo. Three Mini Guppys were built between 1967 and 1970.
All three Mini Guppys have been retired. But one of them is saved at the Tillamook Air Museum in Oregon. You can go see it there today!
Fun Facts
- The Mini Guppy got its name because it looked like a chubby fish in the sky.
- The whole tail section could swing sideways to load cargo from the back.
- The Mini Guppy was bigger than a regular airliner but smaller than its sister, the Super Guppy.
- Three Mini Guppys were built, and all three have now been retired from flying.
- The cargo hold was over 100 feet long — longer than a tennis court!
- The Mini Guppy could carry about 23 tonnes of cargo in its giant belly.
- One Mini Guppy is on display at the Tillamook Air Museum in Oregon for everyone to see.
- Designer Jack Conroy wanted a less extreme plane than the Super Guppy, so he created the Mini Guppy.
Kids’ Questions
Why did the Mini Guppy have such a big round top?
The big round top made room for very wide cargo inside the plane. Workers added the bubble shape so the hold could fit large items like airplane parts and big tanks. Without that shape, those bulky objects would never fit!
How did people load cargo into the Mini Guppy?
The whole tail of the plane swung to the side like a door. This opened up the back of the plane completely. Workers could then roll or slide long cargo straight into the hold from behind.
Where can I see a Mini Guppy today?
One Mini Guppy is kept at the Tillamook Air Museum in Oregon. It is preserved there so visitors can see this amazing plane up close. All three Mini Guppys have stopped flying, but this one is saved for history.
Was the Mini Guppy used for space missions?
The Mini Guppy was too small to carry the giant rocket parts used in space programs. Its bigger sister, the Super Guppy, did that job instead. The Mini Guppy was better suited for airplane parts and large industrial cargo.
Variants
- Mini Guppy (MG)
- Original piston-powered variant. One built. Pratt & Whitney R-4360 Wasp Major radials, 4× 3,000 hp. First flight 24 May 1967.
- Mini Guppy Turbine (MGT)
- Re-engined turboprop variant, four Allison 501-D22C turboprops. Two built. Operated commercially by Aero Spacelines, Aero Union, and Erickson Aviation through 1995.
Notable Operators
- Aero Spacelines
- Original builder and 1967-1976 operator. Carried airliner fuselage sections, oil-industry pressure vessels, and miscellaneous outsize cargo on charter. Ceased operations after the company's bankruptcy.
- Aero Union / Erickson / American Jet Industries
- Successor commercial operators after Aero Spacelines's bankruptcy. Each operated the surviving airframes on a small-fleet basis through retirement in 1995.
Frequently Asked Questions
How is the Mini Guppy different from the Super Guppy?
The Mini Guppy has a smaller hold (18-ft / 5.5 m diameter vs. 25-ft / 7.6 m on the Super Guppy) and uses a swing-tail loading arrangement instead of the swing-nose. The Mini Guppy was sized for airliner fuselages; the Super Guppy was sized for Saturn IVB rocket stages.
Are any Mini Guppys still flying?
No — all three were retired by 1995. The surviving airframe (N111AS) is preserved on outdoor display at the Tillamook Air Museum in Tillamook, Oregon (museum site).
What did the Mini Guppy carry?
Airliner fuselage sections (DC-9, DC-10), oil and gas pressure vessels, helicopter ferry loads, and outsize cargo too large for conventional freighters but too small for the Super Guppy. Operated by US and Canadian commercial charter operators through the late 1980s.
Why was the Mini Guppy programme unsuccessful?
The hold size was caught between competitors. Conventional 707-200F freighters could carry most of what the Mini Guppy could carry, more cheaply. Saturn-class rocket stages needed the Super Guppy. Without a captive Apollo-like customer, Mini Guppy operating economics were difficult.
What aircraft were the Mini Guppys built from?
Boeing 377 Stratocruiser airframes — the same donor type used for the Pregnant Guppy and Super Guppy. The original tube fuselage was cut and a new bubble upper section built above. Wings and lower fuselage were largely original 1940s Boeing structure.
Sources
See Also
- Aero Spacelines Super Guppy — Larger sister Guppy variant
- Aero Spacelines Pregnant Guppy — Original Guppy predecessor
- Boeing 377 Stratocruiser — Donor airframe for the Guppy family
- Conroy Skymonster — Sister Conroy outsize-cargo conversion
- Airbus Beluga / BelugaXL — Modern outsize-cargo successor