Twin-boom aircraft

A twin-boom aircraft is characterised by two longitudinal booms (extended nacelle-like bodies). The booms may contain ancillary items such as fuel tanks and/or provide a supporting structure for other items. Typically, twin tailbooms support the tail surfaces, although on some types such as the Rutan Model 72 Grizzly the booms run forward of the wing. The twin-boom configuration is distinct from twin-fuselage designs in that it retains a central fuselage.

Fairchild C-119 Flying Boxcar, doing a parachute drop from the rear
de Havilland Vampire T.11, whose booms keep the rear fuselage clear of the jet exhaust
Caproni Ca.3, whose booms provided clearance for a propeller - and a position for a gunner to fire to the rear

DesignEdit

The twin-boom configuration is distinct from the twin fuselage type in having a separate, short fuselage housing the pilot and payload. It has been adopted to resolve various design problems with the conventional empennage for aircraft in different roles.

Engine mountingEdit

For a single engine with a propeller in the pusher configuration or a jet engine, a conventional tail requires the propeller or exhaust to be moved far aft, requiring either a very long driveshaft or jet pipe and thus reducing propulsive efficiency. The twin-boom configuration allows a much shorter and more efficient installation.[1] The Saab 21 was originally built as a pusher type and was later adapted to jet power as the 21R.[2]

In these designs, the tailplane (horizontal stabilizer) is typically high-mounted on twin tail fins to keep it clear of the engine wake. The Scaled Composites SpaceShipOne and SpaceShipTwo sub-orbital spaceplanes adopted twin booms with outboard tails or outboard horizontal stabilizers (OHS) to keep the airframe clear of the more widely-spreading rocket engine exhaust.

Twin booms have also been adopted for twin-engined designs where the engine system includes bulky additional items such as turbochargers and heat exchangers, taking up a large volume of space. Examples include the Lockheed P-38 Lightning.

Field of viewEdit

For a rear observation or gunnery position to have an unobstructed field of view, placing it at the rear of a conventional tail moves it so far aft that problems arise with the centre of mass and balancing the aircraft. Getting rid of the conventional empennage allows the rear position to be located more forward, resolving the balance problem. An example is provided by the Focke-Wulf Fw 189.

However the twin booms and bridging tailplane still obstruct the field of view to some extent and guns in this position are especially restricted in firing to the side.

Transport accessEdit

Loading and unloading large freight or cargo items such as vehicles and containers requires large access doors. In conventional designs these doors must be located at the nose or side of the fuselage, necessitating heavy reinforcement of the main structure. Side doors limit the length of an item to the width of the door and access may also be obstructed by engines or undercarriage. The twin-boom configuration allows a large door to be placed at the rear of the fuselage, free from obstruction by the tail assembly, as on the Armstrong Whitworth AW.660 Argosy.

However access to the rear door remains limited, especially for trucks backing up to it, and a high-mounted conventional rear fuselage is often preferred.

EfficiencyEdit

Twin booms typically offer greater drag than a conventional arrangement. They are also typically shallower than the fuselage and thus inherently less stiff, requiring additional reinforcement to maintain a rigid tail position in pitch. On the other hand tip effects on the tailplane are avoided and it is supported at both ends, allowing it to be made smaller and lighter. Moreover, span loading along the wing can reduce the structural forces between the booms and thus overall weight.

Some modern high-efficiency designs have twin booms which distribute the load along the wing span and/or stiffen the overall structure. Capable of flying non-stop round the world, the Rutan Voyager was a canard design with tractor propeller, in which the twin booms extended forwards to brace the foreplane as well as aft to support twin fins. The later Virgin Atlantic GlobalFlyer was jet propelled but with a similar range, still with large twin booms to accommodate the jet fuel in a lightweight span-loaded structure, but with a small conventional tail on each boom.

HistoryEdit

Twin boom designs can trace their history back to the lattices of booms used on many early boxkite aircraft. With the recognition of the tremendous drag these imposed, more compact structures covered in fabric were developed during the World War One. Prime examples include the Caproni series of trimotor bombers.

Around the same time, the first wooden monocoque fuselages appeared, and it wasn't long before this technique was applied to provide twin booms. Possibly the first of these was the pre-war Nieuport pusher, which used paper impregnated with Bakelite however the most successful were the AGO C.I and C.II which used a more conventional wooden shell, built up from strips of wood glued over a form. With the development of aluminium stressed skin monocoques later in World War One, the same technique was extended to twin boom designs, beginning in the 1920s.

Most of the early designs used twin booms to clear a rear mounted propeller, however even in World War One, several larger aircraft used them to provide a gunner with the ability to cover the underside of the tail without having to have the weight at the very extreme end of the aircraft where it posed balance and control problems.

Only in World War Two, with the increasing prevalence of transporting bulky items and vehicles by air was the utility of a rear door, in line with the cabin to ease loading realized, and with it, the utility of moving the rear fuselage structure to the sides to avoid excessive height in the rear fuselage as on the Gotha Go 242 glider.

With the beginning of the jet age, the need for clearance for the propeller was replaced with the need to provide a clear path for hot exhaust gases. Jet engine efficiency was hampered by long intake and exhaust trunks, as were used on many early designs, and one solution was to use twin booms to shorten the exhaust trunking to the minimum, such as de Havilland used on their successful Vampire and Venom jet fighters.

A small number of designs used twin booms for other reasons, most notable being the Lockheed P-38 Lightning, whose booms contained the overly lengthy engine turbo-superchargers, which would have made for an unusually long nacelle. The final use for a twin boom to be developed was in tying together very high aspect ratio wings and canards as on the Rutan Voyager, to reduce flexing, and the weight needed to otherwise constrain it. Also, by having the mass from most of the fuel mid-span, it reduces the forces on the wings considerably, much in the same manner mounting the engines mid-span on most jet transports does.

Despite these anticipated benefits, twin booms remain unusual. For most cases, the booms are less efficient structurally in providing pitch stiffness, and produce more drag. In the case of those using twin booms to improve the field of fire downwards, it severely reduces it laterally, and often directly astern. For transports, the booms may facilitate access to the fuselage, but trucks then have to be extremely careful to not hit parts of the aircraft that they are then getting closer to. As a result, the C-119 remained an anomaly, and most successful post-war transports, such as the C-130 Hercules, reverted to a single rear fuselage.

Even worse, at transonic speeds attained in long power on terminal dives, the location of the tail on the P-38 caused it to be blanked by the wing and fuselage , which caused Mach tuck, when the nose would pitch down violently and dangerously, although it was otherwise extremely forgiving.[citation needed] It is also unclear that the twin booms really offered any advantages over a conventional fuselage and extended nacelles, which worked well in several other designs.

List of twin-boom aircraftEdit

Type Country Class Role Date Status No. Notes
AAI RQ-7 Shadow US UAV UAV 1991
Abrams P-1 Explorer US Propeller Survey 1937 Prototype 1
AD Seaplane Type 1000 UK Propeller Bomber 1916 Prototype 2
Adam A500 US Propeller Transport 2002 Prototype 7
Adam A700 US Jet Transport 2003 Prototype 2
ADI Condor US Propeller Motor glider 1981 Prototype 1
AeroRIK Dingo Russia Propeller Utility 1997 Prototype 1-5 [3]
AGO C.I Germany Propeller Reconnaissance 1915 Production 64
AGO C.II Germany Propeller Reconnaissance 1915 Production 15
AHRLAC Holdings Ahrlac South Africa Propeller Attack 2014 Prototype 1
Air Utility AU-18 US Propeller Transport 1945 Prototype 1 [4]
Airmaster Avalon 680 US Propeller Transport 1983 Prototype 1 [5]
Airsport Song Czech Republic Propeller Ultralight 2009 Production unk.
AISA GN Spain Autogyro Utility 1982 Prototype 1
Akaflieg Stuttgart fs28 Avispa Germany Propeller Utility 1972 Prototype 1
Alaparma Baldo Italy Propeller Utility 1949 Production 35 ca.
Alenia Aermacchi Sky-Y Italy UAV UAV 2007
American Gyro AG-4 Crusader US Propeller Utility 1935 Prototype 1
Antonov LEM-2/OKA-33 USSR Propeller Transport 1937 Prototype 1 [6]
Anderson Greenwood AG-14 US Propeller Utility 1947 Prototype 5
ANTEX-M Portugal UAV UAV 2002
Antonov A-40 USSR Glider Transport 1942 Prototype 1
Arado E.340 Germany Propeller Bomber n/a Project 0
Armstechno NITI Bulgaria UAV UAV 2006
Armstrong Whitworth AW.660 Argosy UK Propeller Transport 1959 Production 74
Arpin A-1 UK Propeller Utility 1938 Prototype 1
AVE Mizar US Propeller Flying car 1973 Prototype 2
BAE Systems Phoenix UK UAV UAV 1986
BAE Systems SkyEye UK UAV UAV 1973
BAT Crow UK Propeller Ultralight 1920 Prototype 1
Bell XP-52 US Propeller Fighter 1940 Project 0
Belyayev EOI USSR Propeller Fighter 1939 Project 0
Bendix 51 & 51A US Propeller Utility 1945 Prototype 2
Bestetti BN.1 Italy Propeller Utility 1940 Prototype 1 [7]
Blériot 125 France Propeller Transport 1931 Prototype 1
Blohm & Voss BV 138 Germany Propeller Reconnaissance 1937 Production 297
Boeing Insitu RQ-21 Blackjack US UAV UAV 2012
Bryan Autoplane US Propeller Flying car 1953 Prototype 2
Bryant Dole Racer Angel of Los Angeles US Propeller Racer 1927 Prototype 1 [8]
Burnelli CBY-3 Canada Propeller Transport 1944 Prototype 1
Burnelli GX-3 US Propeller Experimental 1929 Prototype 1
Burnelli UB-14 US Propeller Transport 1934 Prototype 2
Burnelli UB-20 US Propeller Transport 1930 Prototype 1 [9]
Buscaylet-de Monge 7-4 France Propeller Experimental 1923 Prototype 1
Buscaylet-de Monge 7-5 France Propeller Transport 1925 Prototype 1
Campbell Model F US Propeller Utility 1935 Prototype 1 [10]
Canaero Toucan Canada Propeller Ultralight 1983 Production 41+
Caproni Ca.1 Italy Propeller Bomber 1914 Production 162
Caproni Ca.2 Italy Propeller Bomber 1915 Production 9
Caproni Ca.3 Italy Propeller Bomber 1916 Production 269-383
Caproni Ca.4 Italy Propeller Bomber 1917 Production 44-53
Caproni Ca.5 Italy Propeller Bomber 1917 Production 662
Caproni Ca.37 Italy Propeller Attack 1916 Prototype 1
Caproni Ca.61 Italy Propeller Bomber 1922 Prototype 1-2
CarterCopter US Autogyro Transport 1998 Prototype 1
Celier Xenon 2 Poland Autogyro Utility 2005 Production 100+
Cessna Skymaster US Propeller Transport 1961 Production 2,993
Cessna XMC US Propeller Experimental 1971 Prototype 1
Commuter Craft Innovator US Propeller Transport 2015 Prototype 1 [citation needed]
Conroy Stolifter US Propeller Utility 1968 Prototype 1
Continental KB-1 US Propeller Reconnaissance 1916 Prototype 1
Convair 106 Skycoach US Propeller Utility 1946 Prototype 1
Convair Model 48 Charger US Propeller Attack 1964 Prototype 1
Creative Flight Aerocat Canada Propeller Transport 2001 Prototype 1
Cunliffe-Owen OA-1 UK Propeller Transport 1939 Prototype 1
Curtis Wright 21 US Propeller Utility 1947 Prototype 1 [11]
Curtiss Autoplane US Propeller Flying car 1917 Prototype 1 [note 1]
Curtiss CT US Propeller Bomber 1921 Prototype 1
De Havilland Sea Vixen UK Jet Fighter 1951 Production 145
De Havilland Vampire UK Jet Fighter 1943 Production 3,268
De Havilland Venom & Sea Venom UK Jet Fighter 1952 Production 1,431
De Schelde S.20 Netherlands Propeller Trainer 1940 Prototype 1
De Schelde S.21 Netherlands Propeller Fighter 1940 Prototype 1 [note 1]
Difoga 421 Netherlands Propeller Utility 1946 Prototype 1 [12]
Dyle et Bacalan DB-70 France Propeller Transport 1929 Prototype 1
Doblhoff WNF 342 Germany Helicopter Reconnaissance 1943 Prototype 3
DRDO Nishant India UAV UAV 1996
Edgley Optica UK Propeller Reconnaissance 1979 Production 22
Eldred Flyer's Dream US Propeller Utility 1946 Prototype 1 [13]
Emsco B-8 Flying Wing US Propeller Record 1930 Prototype 1
Fairchild C-82 Packet US Propeller Transport 1944 Production 223
Fairchild C-119 Flying Boxcar US Propeller Transport 1947 Production 1,183
Fairchild XC-120 Packplane US Propeller Transport 1950 Prototype 1
Friedrichshafen FF.34 Germany Propeller Bomber 1916 Prototype 1
Focke-Wulf Fw 189 Germany Propeller Reconnaissance 1938 Production 864
Focke-Wulf Flitzer Germany Jet Fighter 1944 Project 0
Focke-Wulf Project VIII Germany Propeller Fighter n/a Project 0
Fokker D.XXIII Netherlands Propeller Fighter 1939 Prototype 1
Fokker F.25 Netherlands Propeller Utility 1946 Production 20
Fokker G.I Netherlands Propeller Fighter 1937 Production 63
General Airborne XCG-16 US Glider Transport 1943 Prototype 2
General Aircraft Cagnet UK Propeller Trainer 1939 Prototype 1
General Aircraft GAL.47 UK Propeller Reconnaissance 1940 Prototype 1
Ghods Mohajer Iran UAV UAV 1981
Gotha Go 242 Germany Glider Transport 1941 Production 1,528
Gotha Go 244 Germany Propeller Transport 1942 Production 174
Gotha WD.3 Germany Propeller Reconnaissance 1915 Prototype 1
Grahame-White Ganymede UK Propeller Bomber 1918 Prototype 1
Groen Hawk 4 US Autogyro Utility 1997 Prototype 3
Grokhovsky G-37 USSR Propeller Transport 1934 Prototype 1 [14]
Grokhovsky G-38 USSR Propeller Fighter-bomber 1934 Project 0 [15]
Grokhovsky G-39 Cucaracha USSR Propeller Fighter 1935 Prototype 1 [16]
Häfeli DH-1 Switzerland Propeller Reconnaissance 1916 Production 6
Hanriot H.110 & H.115 France Propeller Fighter 1933 Prototype 1
Henderson H.S.F.1 UK Propeller Transport 1929 Prototype 1
Heston JC.6 UK Propeller Reconnaissance 1947 Prototype 2
Hughes D-2 US Propeller Fighter-bomber 1942 Prototype 1
Hughes XF-11 US Propeller Reconnaissance 1946 Prototype 2
HWL Pegaz Poland Propeller Motor glider 1949 Prototype 1
Hydra Technologies Ehécatl Mexico UAV UAV 2006
IAI Arava Israel Propeller Transport 1969 Production 103
IAI Heron Israel UAV UAV 1994
IAI Scout Israel UAV UAV 1981
IAI Searcher Israel UAV UAV 1992
Ikarus 452M Yugoslavia Jet Experimental 1953 Prototype 2
Ion Aircraft Ion US Propeller Utility 2007 Prototype 1
I.S.T. XL-15 Tagak Philippines Propeller Utility 1954 Prototype 1
Johns Multiplane US Propeller Bomber 1919 Prototype 1
Kalinin K-7 USSR Propeller Experimental 1933 Prototype 1
Kaman HH-43 Huskie US Helicopter Utility 1947 Production 193
Kamov Ka-26 USSR Helicopter Utility 1965 Production 816
Kamov Ka-126 USSR Helicopter Utility 1988 Production 17
Kamov Ka-226 Russia Helicopter Utility 1997 Production 69
Kingsford Smith PL.7 Australia Propeller Agricultural 1956 Prototype 1
Kokusai Ki-105 Otori Japan Propeller Transport 1945 Prototype 9
Kokusai Ku-7 Japan Glider Transport 1942 Prototype 2
Kortenbach & Rauh Kora 1 Germany Propeller Motor glider 1973 Prototype 2
Larkin Skylark US Propeller Utility 1973 Prototype 1
Lawrence Special US Propeller Racer 1949 Prototype 1 [17]
Levasseur PL.200/201 France Propeller Reconnaissance 1935 Prototype 1
Lockheed P-38 Lightning US Propeller Fighter 1939 Production 10,037
Lockheed XP-49 US Propeller Fighter 1942 Prototype 1
Lockheed XP-58 Chain Lightning US Propeller Fighter 1944 Prototype 1
Lloyd 40.08 Luftkreuzer Germany Propeller Bomber 1916 Prototype 1
LWF model H Owl US Propeller Transport 1919 Prototype 1 [18]
Maeda Ku-1 Japan Glider Trainer 1941 Production 100
Macchi M.12 Italy Propeller Bomber 1918 Production 10 ca.
Mansyū Ki-98 Japan Propeller Attack 1945 Prototype 1 [note 1]
McCulloch J-2 US Autogyro Utility 1962 Production 83+
McDonnell XV-1 US Autogyro Experimental 1954 Prototype 2
McGaffey Aviate US Propeller Utility 1935 Prototype 1 [19]
Millet Lagarde ML-10 France Propeller Utility 1949 Prototype 2
Mikoyan MiG-110 Russia Propeller Transport 1995 Project 0
Mirach 26 Italy UAV UAV 1992
Mitsubishi J4M Japan Propeller Fighter n/a Project 0
Moskalyev SAM-13 USSR Propeller Fighter 1940 Prototype 1
Moskalyev SAM-23 USSR Propeller Fighter 1943 Project 0 [citation needed]
Myasishchev M-17 and M-55 USSR Jet Reconnaissance 1978 Production 8+
Nieuport seaplane pusher France Propeller Reconnaissance 1913 Prototype 1 [20]
Nord Noratlas France Propeller Transport 1949 Production 425
North American OV-10 Bronco US Propeller Attack 1965 Production 360
Northrop F-15 Reporter US Propeller Reconnaissance 1945 Production 36
Northrop Flying Wing US Propeller Experimental 1929 Prototype 1 [21]
Northrop Grumman Firebird US Propeller Reconnaissance 2010 Prototype 1
Northrop P-61 Black Widow US Propeller Fighter 1942 Production 706
NPO Molniya Molniya-1 Russia Propeller Utility 1992 Prototype 2
OMA SUD Skycar Italy Propeller Utility 2007 Prototype 1
Otto C.I Germany Propeller Reconnaissance 1915 Production 25
PAL-V Netherlands Helicopter Flying car 2012 Prototype 1
Piper PA-7 Skycoupe US Propeller Utility 1944 Prototype 1
Pitcairn XO-61 US Autogyro Reconnaissance 1943 Prototype 2
Pocino PJ.1A France Propeller Ultralight 1989 Prototype 1
Portsmouth Aerocar UK Propeller Utility 1947 Prototype 1
Potez 75 France Propeller Attack 1953 Prototype 1
Praga E-51 Czechoslovakia Propeller Reconnaissance 1938 Prototype 1 [22]
Puget Pacific Wheelair III-A US Propeller Utility 1947 Prototype 1 [23]
PZL M-15 Belphegor Poland Jet Agricultural 1973 Production 175
PZL M-17 Poland Propeller Trainer 1973 Prototype 1
Rice Knowlton Volante US Propeller Flying Car 1981 Prototype 1 [24]
Rutan Grizzly US Propeller Experimental 1982 Prototype 1
Rocheville Arctic Tern US Propeller Record 1932 Prototype 1 [25]
Rotor Flight Dynamics LFINO US Autogyro Experimental 2006 Prototype 1
RTAF-5 Thailand Propeller Trainer 1984 Prototype 1
RUAG Ranger Switzerland / Israel UAV UAV 1999
Rutan Voyager US Propeller Record 1984 Production 1
S-TEC Sentry US UAV UAV 1986
Saab 21 Sweden Propeller Fighter 1943 Production 298
Saab 21R Sweden Jet Fighter 1947 Production 64
SAB AB-20 & 21 France Propeller Bomber 1932 Prototype 2
Sadler Vampire US Propeller Ultralight 1982 Production unk.
SAIMAN LB.2 Italy Propeller Utility 1937 Prototype 1
Savoia-Marchetti S.64 Italy Propeller Record 1928 Prototype 2
Savoia-Marchetti S.65 Italy Propeller Racer 1929 Prototype 1
Savoia-Marchetti SM.88 Italy Propeller Fighter 1939 Prototype 1
Savoia-Marchetti SM.91 Italy Propeller Fighter-bomber 1943 Prototype 1
Scaled Composites ARES US Jet Attack 1990 Prototype 1
Scaled Composites ATTT US Propeller Transport 1986 Prototype 1
Scaled Composites Pond Racer US Propeller Racer 1991 Prototype 1
Scaled Composites Proteus US Jet Experimental 1991 Prototype 1
Scaled Composites SpaceShipOne US Rocket Spaceplane 2003 Prototype 1
Scaled Composites SpaceShipTwo US Rocket Spaceplane 2010 Prototype 2
Scaled Composites White Knight US Jet Transport 2002 Prototype 1
Schneider Sch-10M France Propeller Bomber 1925 Prototype 1
Schwade Kampfeinsitzer Nr 2 Germany Propeller Fighter 1916 Prototype 1 [26]
Schweizer RU-38 Twin Condor US Propeller Reconnaissance 1995 Prototype 5
SECAN Courlis France Propeller Utility 1946 Production 144
Selex ES Falco Italy UAV UAV 2003
SIAI-Marchetti FN.333 Riviera Italy Propeller Utility 1952 Production 29
Siemens-Schuckert L.I Germany Propeller Bomber 1918 Prototype 3
Siemens-Schuckert R.I Germany Propeller Bomber 1915 Prototype 1
Sikorsky S-38 US Propeller Transport 1928 Production 101
Sikorsky S-39 US Propeller Transport 1929 Production 23+
Sikorsky S-40 US Propeller Transport 1931 Production 3
Sikorsky S-41 US Propeller Transport 1930 Production 7
SIPA S.200 Minijet France Jet Trainer 1952 Prototype 7
Škoda Kauba Sk V6 Czechoslovakia Propeller Experimental 1944 Prototype 1 [27]
SNCAC NC.1070 France Propeller Attack 1947 Prototype 1
SNCAC NC.1071 France Jet Attack 1948 Prototype 1
SNCASO SO.8000 Narval France Propeller Fighter 1949 Prototype 2
SPCA 30 France Propeller Bomber 1931 Prototype 2
Spectrum SA-550 US Propeller Utility 1983 Prototype 2+
Stearman-Hammond Y-1 US Propeller Utility 1931 Production 20 ca.
Stout Skycar US Propeller Transport 1941 Prototype 4
Sukhoi Su-12 USSR Propeller Reconnaissance 1947 Prototype 1
Sukhoi Su-80 Russia Propeller Transport 2001 Prototype 8
Tachikawa Ki-94-I Japan Propeller Fighter n/a Project 0
TAI Baykuş Turkey UAV UAV 2003
Teledyne Ryan Model 410 US UAV UAV 1988
Terrafugia Transition US Propeller Flying car 2009 Prototype 2
THK-11 Turkey Propeller Utility 1947 Prototype 1
Thomas-Morse MB-4 US Propeller Transport 1920 Prototype 4
Transavia PL-12 Airtruk Australia Propeller Agricultural 1965 Production 118
Trella T-106 US Propeller Utility 1949 Prototype 1 [28]
Trella T-107 US Propeller Transport 1954 Project 0 [29]
Tupolev I-12/ANT-23 USSR Propeller Fighter 1931 Prototype 1
Vance Viking US Propeller Racer 1932 Prototype 1
Virgin Atlantic GlobalFlyer US Jet Record 2005 Production 1
Voisin E.28 France Propeller Bomber 1919 Prototype 1
Voisin Triplane France Propeller Bomber 1915 Prototype 1
Vultee XP-54 US Propeller Fighter 1943 Prototype 2
Vultee XP-68 Tornado US Propeller Fighter n/a Project 0
Wagner Aerocar Germany Helicopter Flying car 1965 Prototype 1
Weick W-1 US Propeller Experimental 1934 Prototype 1
Weymann 66 France Propeller Transport 1933 Prototype 1
Willoughby Delta 8 UK Propeller Experimental 1939 Prototype 1
Willoughby Delta 9 UK Propeller Transport 1939 Project 0
WLT Sparrow Czech Republic Propeller Ultralight 2010 Production 13
WNF Wn 16 Austria Propeller Experimental 1939 Prototype 1
Yakovlev Yak-58 Russia Propeller Utility 1993 Prototype 7
Yakovlev Yak-141 Russia Jet Fighter 1987 Prototype 4

See alsoEdit

ReferencesEdit

NotesEdit

  1. ^ a b c did not fly

CitationsEdit

  1. ^ Martyn Chorlton and Tony Buttler; "De Havilland's First-Generation Interceptor", Vampire, Aeroplane Icons, 2014. Page 6.
  2. ^ Green & Swanborough (1994), pp.512-3.
  3. ^ Savine, Alexandre (13 November 2000). "'Dingo' amphibian by NPP "AeroRIK" (Designer General Viktor Morozov)". Russian Aviation Museum. Retrieved 16 December 2019.
  4. ^ Various (2 May 2009). "American Airplanes: Ab-Ak". Aerofiles.com. Retrieved 16 December 2019.
  5. ^ Various (2 May 2009). "American Airplanes: Ab-Ak". Aerofiles.com. Retrieved 16 December 2019.
  6. ^ Savine, Alexandre (27 July 1998). "LEM-2, OKA-33 by O.K.Antonov, L.P.Malinovskij". Russian Aviation Museum. Retrieved 16 December 2019.
  7. ^ Brotzu, Emilio; Caso, Michele; Garello, Giancarlo (1977). Scuola-Collegamento Volume 2. Dimensione Cielo, Aerei Italiani nella 2ª Guerra Mondiale Vol.11 (in Italian). Rome: Edizioni dell'Ateneo & Bizzarri. pp. 87–92.
  8. ^ Various (2 May 2009). "American Airplanes: Bo-Bu". Aerofiles.com. Retrieved 16 December 2019.
  9. ^ Various (13 October 2009). "Burnelli". Aerofiles.com. Retrieved 16 December 2019.
  10. ^ Various (15 August 2008). "American airplanes: Ca - Ci". Aerofiles.com. Retrieved 16 December 2019.
  11. ^ Various (3 August 2008). "American airplanes: Cu - Cy". Aerofiles.com. Retrieved 16 December 2019.
  12. ^ Wesselink, Theo. Difoga 421 en Fokker F.25 Promotor (in Dutch). Netherlands: Wesselink. ISBN 978-9491993145.
  13. ^ Various (16 October 2008). "American airplanes: Ea - Ew". Aerofiles.com. Retrieved 16 December 2019.
  14. ^ Maslov, B.; Kapustyan, A.; Komsomolsk on Amure, G. (2003). "Гроховский Г-37 "УЛК" (Grokhovsky G-37 "ULK")". Avia Museum Narod. Retrieved 16 December 2019.
  15. ^ Savine, Alexandre (2 January 2001). "G-38, LK-2 (Light Cruiser) multirole aircraft project by P.L.Grokhovskij, P.A.Ivensen". Russian Aviation Museum. Retrieved 16 December 2019.
  16. ^ Savine, Alexandre (21 October 2000). "G-39 Cucaracha by P.I.Grokhovskij, V.F.Bolkhovitinov, S.G.Kozlov, A.E.Kaminov". Russian Aviation Museum. Retrieved 16 December 2019.
  17. ^ Various (16 April 2008). "American airplanes: La - Li". Aerofiles.com. Retrieved 16 December 2019.
  18. ^ Various (2 September 2008). "American airplanes: Lo - Lu". Aerofiles.com. Retrieved 16 December 2019.
  19. ^ Various (2 April 2009). "American airplanes: Ma - Me". Aerofiles.com. Retrieved 16 December 2019.
  20. ^ Sanger, Ray (2002). Nieuport Aircraft of World War One. Wiltshire: Crowood Press. pp. 28–29. ISBN 978-1861264473.
  21. ^ Various (8 August 2008). "Northrop". Aerofiles.com. Retrieved 16 December 2019.
  22. ^ Němeček, V. (1983). Československá letadla 1918-1945 (Czechoslovak aircraft 1918-1945) (in Czech). Prague: Naše Vojsko (Our Troops).
  23. ^ Various (18 November 2008). "American airplanes: Wh - Wy". Aerofiles.com. Retrieved 16 December 2019.
  24. ^ Various (17 April 2009). "American airplanes: U - V". Aerofiles.com. Retrieved 16 December 2019.
  25. ^ Various (12 October 2008). "American airplanes: Ro - Ry". Aerofiles.com. Retrieved 16 December 2019.
  26. ^ Green & Swanborough (1994), Page 521.
  27. ^ Němeček, Václav (1983). Československá letadla 1918-1945. Československá letadla (Czechoslovakian airplanes) (in Czech). Prague: "Naše vojsko (Our Army)".
  28. ^ Various (2 May 2009). "American airplanes: Ti - Ty". Aerofiles.com. Retrieved 16 December 2019.
  29. ^ Various (2 May 2009). "American airplanes: Ti - Ty". Aerofiles.com. Retrieved 16 December 2019.

BibliographyEdit

  • Green, W. and Swanborough, G.; The complete book of fighters, Salamander, 1994.