Twin-fuselage aircraft

A twin-fuselage aircraft has two main fuselages. It is distinct from the twin-boom configuration which has a single main fuselage with two subsidiary boom structures.

The North American XP-82 Twin Mustang (photographed in 1945) incorporated a twin-fuselage design.

The Scaled Composites White Knight Two

Twin fuselages have been adopted for various reasons, and a few types have entered production.

Early seaplanes

During and after World War I a number of twin-fuselage floatplanes and twin-hulled flying boats were constructed, and several entered production:

The Blackburn T.B. of 1915 was a long-range floatplane for anti-Zeppelin patrol. A handful of production examples were delivered but few were used operationally.

The British Wight Twin Seaplane of 1916 was a prototype long-range floatplane intended to carry an 18-inch torpedo. Its design was a twin-fuselage variant of the earlier Wight Twin Landplane of twin-boom configuration, i.e. with the central nacelle removed and the crew housed in the remaining bodies on either side. The French Labourdette-Halbronn H.T. 1 and H.T.2 flying boat prototypes of 1918-1919 were intended for a similar role.

Savoia-Marchetti produced two twin-hulled flying boat types, the S.55 multirole flying boat of 1924 and the S.66 airliner of 1931, both of which took advantage of a twin hull/fuselage to provide the same stability of a twin float design, but with a hull. The S.55 proved very successful, being produced in large numbers.

The Tupolev ANT-22 flying boat prototype conceptually followed the Savoia's, but was much larger and despite flying in 1934 never progressed beyond a single prototype due to poor performance.

Heavy glider tug

During World War II the need arose for a heavy glider tug capable of towing the large Gotha Go 242 and even larger Messerschmitt Me 321 Gigant. The Heinkel He 111Z Zwilling (twin) was created by joining two He 111 fuselages with a new wing centre section and adding a fifth central engine. Although liked by its pilots when it first flew in 1941, even the 111Z could not tow a fully laden Gigant, and although a small batch became operational they saw little action.

A few variants were developed for roles such as long-range reconnaissance or air-launched anti-ship missile carrier, but none entered service.

Heavy fighters

During World War II a need arose for a heavy fighter, which could not be met by a new design proposal in a reasonable time frame. Joining two examples of an existing light fighter aircraft was one way to achieve this.

The German Messerschmitt Bf 109Z twin (Zwilling) Bf 109 prototype was destroyed in an attack by the British in 1943 before it was completed, and the project subsequently abandoned. The later Me 609 twin Me 309 project was never built.

In 1944 Dornier proposed the Dornier Do 635 long-range reconnaissance variant of the Do 335 Pfeil heavy fighter, to have twin Do 335 fuselages and four engines. It was never built.

The Italian Savoia-Marchetti SM.92 prototype was unusual in being an adaptation of a twin-boom design but did not enter production.

The North American F-82 Twin Mustang arrived too late to enter service during the War but later saw service in the Korean war.

Space launchers

More recently the idea of a dedicated re-usable mothership design capable of carrying and launching a spacecraft has gained interest. The twin fuselage configuration offers the advantage of a clean payload area underneath the wing centre section.

The Scaled Composites White Knight Two is under development, with the first example now flying.

Past projects have included the Conroy Virtus and Twin fuselage Lockheed C-5 Galaxy Shuttle transport aircraft of 1974.

Current projects include the Scaled Composites Model 351 Roc proposed for Stratolaunch and NASA's Towed Glider Air-Launch Concept.

List of twin-fuselage aircraft

Types are listed in chronological order of first flight or, for those which never flew, of project announcement.

Type	Country	Class	Role	Date	Status	No.	Notes
Belyayev DB-LK	USSR	Propeller	Bomber	1940	Prototype
Bestetti BN.1	Italy	Propeller	Private	1940			Sportplane.
Blackburn T.B.	UK	Propeller	Patrol	1915	Production		Floatplane.
Blériot 125	France	Propeller	Transport	1931	Prototype		12 seat airliner.
Caproni Ca.4	Italy	Propeller	Bomber and transport	1915	Production		Series of types.[1]
Conroy Virtus	USA	Propeller	Transport	1974	Project	0	Shuttle transport
Dornier Do 635	Germany	Propeller	Fighter	1944	Project	0	Twin Dornier Do 335 Pfeil proposal.
Twin Ercoupe	USA	Propeller		1946			Twin ERCO Ercoupe one-off conversion.
Fokker K.I	Germany	Propeller		1915	Prototype		Kampfflugzeug (twin fuselage with nacelle)
Fouga CM.88 Gemeaux	France	Jet	Experimental	1951	Operational		Twin Cyclope, jet engine testbed, 2 built[2]
General Aircraft Twin Hotspur	UK	Glider	Experimental	1942			Twin General Aircraft Hotspur
Heinkel He 111Z	Germany	Propeller	Utility	1941	Production		Glider tug. Variant of the He 111.
Labourdette-Halbronn H.T.1	France	Propeller	Torpedo bomber	1918	Prototype		Flying boat. One H.T.1 (1918) flown.[3]
Labourdette-Halbronn H.T.2	France	Propeller	Torpedo bomber	1919	Prototype		Flying boat. Two H.T.2 (1919) flown.[3]
Twin fuselage Lockheed C-5 Galaxy	USA	Jet	Transport	1974	Project	0	Shuttle transport aircraft proposal.[4][5]
Messerschmitt Bf 109Z	Germany	Propeller	Fighter	1943	Project	0	Twin Bf 109 prototype. Destroyed while under construction.[6]
Messerschmitt Me 609	Germany	Propeller	Fighter	1941	Project	0	Twin Me 309 proposal.[6]
North American F-82 Twin Mustang	USA	Propeller	Fighter	1945	Production	272	Long-range.
Pipistrel Taurus G4	Slovenia	Propeller	Experimental	2011	Prototype		Electric aircraft and competition winner.
Ricci R.1	Italy	Propeller		1917	Prototype		Flying-boat
Savoia-Marchetti S.55	Italy	Propeller	Multirole	1924	Production		Flying boat.
Savoia-Marchetti S.66	Italy	Propeller	Transport	1931	Production		Flying boat.
Savoia-Marchetti SM.92	Italy	Propeller	Fighter	1943	Prototype
Scaled Composites Model 348 White Knight Two	USA	Jet	Spacecraft launcher	2008	Prototype
Scaled Composites Model 351 Roc	USA	Jet	Spacecraft launcher	2019	Prototype		Launcher for Stratolaunch spacecraft.
Scaled Composites Model 367 BiPod	USA	Propeller	Experimental	2011	Prototype		Flying car, carried out "hops" under wheeled power.
Thomas-Morse MB-4	USA	Propeller	Utility	1920	Prototype		Mail plane
Towed Glider Air-Launch Concept	USA		Spacecraft launcher	2013	Project	0	NASA Dryden[7]
Tupolev ANT-22	USSR	Propeller		1934	Prototype		Flying boat.
Wagner Twin Cub	USA	Propeller		1952	Prototype		Twin Piper Cub one-off conversion.[8]
Wight Twin Seaplane	UK	Propeller		1916	Prototype		Variant of the Wight Twin Landplane of twin boom configuration.

References

Notes

1. "The Caproni Bombing Triplane CA-4-1915", Flight, Volume XI, Issue 25, No. 547, 19 June 1919, pp. 797–799. Retrieved: 29 October 2013.
2. http://johnlinde.ca/Early_Designs.html
3. Davilla, J.; French aircraft of the first World War (2002), Flying Machines Press, Page 287
4. Tails through time
5. Shuttling the Shuttle: Twin fuselage C-5 Galaxy
6. Green, W.; Warplanes of the Third Reich, Macdonald and Jane's, 1970.
7. 'Gliding' to Space: A Novel Means of Launching Space Satellites
8. http://www.twinnavion.com/oddballs.htm

Bibliography

• Gunston, Bill, The Cambridge Aerospace Dictionary, Cambridge, Cambridge University Press 2004, ISBN 978-0-521-84140-5/ISBN 0-521-84140-2

See also

• Asymmetrical aircraft
• Composite aircraft