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Skymonster

Conroy Aircraft · Large outsize-cargo transport aircraft · Early Jet (1946–1969)

Skymonster — Large outsize-cargo transport aircraft
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The Conroy Skymonster (factory designation CL-44-O) was a one-off outsize-cargo aircraft built by Conroy Aircraft in 1969 from a Canadair CL-44 swing-tail freighter. The conversion was a simpler approach than the more dramatic Aero Spacelines Guppy series: rather than slicing the upper fuselage off a Boeing 377, Jack Conroy took an existing turboprop freighter with a swing-tail loading system already and added a large bulged upper fuselage to enlarge the hold cross-section. One Skymonster was built and operated commercially under several owners between 1970 and 2022.

The donor aircraft was a Canadair CL-44 — a Rolls-Royce Tyne-powered four-engine turboprop derived from the Bristol Britannia, with a unique swing-tail arrangement. Conroy added a large "hump" running from cockpit to tail, expanding the hold to about 11 ft 8 in (3.55 m) diameter. The aircraft was registered N447T and first flew in 1969 with Conroy at the controls. It was sold soon after to Heavylift Cargo Airlines (UK) and then through a long succession of operators: Transmeridian Air Cargo, RP-C8023 (Philippines), 4K-GUP (Azerbaijan), 9G-LCA (Ghana), and finally back to N447FT in 2013 for a brief revival as a heavy-lift charter freighter.

The Skymonster's commercial niche was haulage of helicopter-sized loads — fuselages of light helicopters, oil-industry pressure vessels, large generators — that fit into its 11.6-ft hold but were too large for conventional 707 or DC-8 freighters. Cruise speed (about 270 knots) and range (about 3,500 nm) were comparable to a CL-44 freighter. The Skymonster's particular value was the swing-tail roll-on/roll-off loading, which was much faster than the side-door loading on most outsize freighters of the era.

The Skymonster was withdrawn from service in 2022 after a final ownership change. It is currently stored at Bournemouth Airport (UK), reportedly in serviceable condition, awaiting either a future operator or scrapping. It is the last surviving Conroy outsize-cargo conversion — the Guppy series passed to Aero Spacelines and Boeing, but the CL-44-O remained Conroy Aircraft's own one-off design.

For Kids — a shorter, friendlier version

The Conroy Skymonster is a very special cargo plane. It was built in 1969 by a company called Conroy Aircraft. Only one was ever made, which makes it truly one of a kind.

The Skymonster started life as a regular Canadair CL-44 freighter. That plane already had a cool swing-tail — its whole tail could swing open to load big cargo. Conroy added a giant hump on top of the plane to make the cargo hold even bigger. The hump ran all the way from the cockpit to the tail.

The cargo hold grew to about the size of a small tunnel. It was bigger than what most other cargo planes could carry at the time. This let the Skymonster haul very large and bulky loads that would not fit anywhere else.

The plane first flew with Jack Conroy as the pilot. It then worked for many different airlines around the world. It flew for companies in Britain, the Philippines, Azerbaijan, and Ghana over the years.

The Skymonster flew for more than fifty years before it was retired. That is a very long life for any aircraft! Today it sits in storage at Bournemouth in England.

Fun Facts

  • Only one Skymonster was ever built — making it one of the rarest cargo planes in the world!
  • The Skymonster has a swing-tail, meaning the entire tail of the plane swings open like a giant door.
  • Jack Conroy himself was at the controls when the plane took its very first flight in 1969.
  • The cargo hold was bigger than a school bus tunnel, letting it carry loads too large for most other aircraft.
  • The plane flew under the flags of at least five different countries during its long life.
  • The Skymonster kept flying commercially all the way from 1970 to 2022 — over fifty years in service!
  • Its four turboprop engines were made by Rolls-Royce and were called Tyne engines.
  • The giant hump on its back ran from just behind the cockpit all the way to the tail.

Kids’ Questions

What made the Skymonster different from other cargo planes?

The Skymonster had a huge hump added to the top of its body. This made the cargo hold much wider so it could carry very large objects. It also had a swing-tail that opened up for easy loading. No other plane looked quite like it!

How did the plane get so big?

A man named Jack Conroy took a normal Canadair CL-44 freighter and added a big bulging hump on top. The hump made the inside of the plane much taller and wider. It was a clever way to carry outsize cargo without building a brand new plane.

Where is the Skymonster now?

The Skymonster is stored at Bournemouth in England. It stopped flying in 2022 after more than fifty years of service. It is one of the last of its kind still around today.

Variants

CL-44-O (Skymonster, sole airframe)
Single conversion of a Canadair CL-44 freighter. First flight 1969 with Jack Conroy at the controls. Originally registered N447T; later EI-BND, 4K-GUP, 9G-LCA, RP-C8023, and N447FT. Stored at Bournemouth, UK as of 2026.

Notable Operators

Heavylift Cargo Airlines
First commercial operator after Conroy. UK-based heavy-lift charter operator that flew the Skymonster on helicopter and outsize-cargo charters from 1970 through the early 1980s.
Transmeridian Air Cargo
Acquired the Skymonster in the late 1970s/early 1980s. Continued the heavy-lift charter business through several ownership changes.
Various subsequent operators
Passed through Philippine, Ghanaian, and Azerbaijani heavy-lift charter operators 1990s-2010s. Returned to U.S. registration as N447FT in 2013 for a brief revival period before final 2022 retirement.

Frequently Asked Questions

What is the Conroy Skymonster based on?

A Canadair CL-44 swing-tail turboprop freighter — a Canadian-built civil derivative of the Bristol Britannia, powered by four Rolls-Royce Tyne turboprops. Conroy added a bulged upper fuselage to expand the hold cross-section to 11.6 ft (3.55 m) diameter.

How is the Skymonster different from the Aero Spacelines Guppy?

The Super Guppy uses a much more aggressive conversion — sliced upper fuselage replaced with a 25-ft bubble — on a Boeing 377 Stratocruiser. The Skymonster is a much milder bulge on a CL-44 turboprop, with a smaller hold (11.6 ft vs. 25 ft) but lower per-mile costs.

Does the Skymonster still exist?

Yes — the single airframe (N447FT) is stored at Bournemouth Airport, UK, as of 2026. Reportedly in serviceable condition; no announced operator. It was last commercially active in 2022.

Who built the Skymonster?

Conroy Aircraft, founded by Jack M. Conroy in 1968 after he sold his interest in Aero Spacelines. The Skymonster was Conroy Aircraft's one outsize-cargo product; the company also did smaller specialised conversions before Conroy's death in 1979.

What did the Skymonster carry?

Helicopter-sized loads — fuselages of light helicopters being delivered or repaired, oil-industry pressure vessels, large generators, and outsize cargo too large for conventional 707 or DC-8 freighters but too small for the Super Guppy or An-124. The swing-tail loading made roll-on/roll-off much faster than side-door alternatives.

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