Four-engine aircraft

Long-haul Airbus A380

Four-engine aircraft are aircraft that are propelled by four jet engines. This design is used in both military and civil aviation. Four-engine aircraft are predominantly classic long- haul aircraft . Nowadays, the Boeing 747 , the Airbus A340 , the Airbus A380 , the Ilyushin Il-96 and in some countries also, for example, the Ilyushin Il-76 and Ilyushin Il-86 as well as on short and medium-haul routes are particularly important in passenger air traffic on long and ultra-long routes the Avro RJ / BAe 146 family . In 2009, around 3200 four-engine models were in use worldwide in the civil and around 1100 in the military.

The first jet aircraft that were important in aviation were the De Havilland DH.106 Comet , Boeing 707 , Douglas DC-8 , Vickers VC-10 and the Ilyushin Il-62 , of which a few except for the Comet and the VC-10 are still in Are operating.

As a result of technical improvements, four -engine models are increasingly being replaced by twin-engine aircraft such as the Boeing 767 , Boeing 777 , Boeing 787 and Airbus A330 as well as the Airbus A350, even on long-haul routes .

historical development

Short- and medium-haul aircraft Avro RJ

As the first four-engine aircraft, a variant of the originally twin -engine Arado Ar 234 C was constructed in several prototypes for use as a bomber during the Second World War in 1945 . From April 1949 the first jet airliner flew the de Havilland Comet from the British manufacturer de Havilland . Two serious accidents in 1950 and 1954, in which two planes broke apart in the air due to material fatigue, gave other companies the opportunity to establish themselves on the market with four-engine civil aircraft, including the US company Boeing with the model series Boeing 707 and Douglas with the series DC-8. New designs were also forced in military use, e.g. B. in the Soviet Union the Myasishchev M-4 and in the USA the North American B-45 . During the Cold War , bombers in particular were equipped with four jet engines because of their greater range and the possibility of a larger payload.

As a result of the increasing passenger traffic since the 1960s, more civil aircraft types with four engines were built, sometimes in very high numbers. The early civil four-engine aircraft that are still best known today include types from the manufacturers Boeing (e.g. Boeing 707, Boeing 747 “Jumbo Jet”), Douglas (e.g. DC-8), Ilyushin (e.g. Il- 62 , Il-86 ) and the Franco-British joint venture Aérospatiale - BAC developed since 1962 supersonic - airliner Concorde . The Convair CV-880 and Convair CV-990 remained rather unsuccessful .

C-141 Starlifter long-range transport aircraft

One of the few business jets with four engines is the Lockheed Jetstar , sold from 1961 , of which over 200 copies were built.

In particular, the Boeing 747 Jumbo Jet wide-body aircraft has radically changed civil air traffic since its maiden flight in 1969. It made connections over long distances with high passenger numbers (approx. 400-550 passengers ) without any problems and increased safety on transoceanic flights with its four engines. The European company EADS has also been creating a four-engine long - haul aircraft with its Airbus A340 since the early 1990s , which today is one of the main modes of transport on long-haul flights . The Airbus A380 was launched in 2005 as the world's largest passenger aircraft with a maximum of around 800 passengers on two continuous decks.

The Avro-RJ family (before 1993: BAe 146) with good short take-off and landing properties plays a major role in city connections for short and medium-haul use up to around 2800 km.

Effects of the ETOPS

Increasing improvements in the reliability of turbofan engines allow more extensive use of twin-engine aircraft in international long - distance air traffic. ETOPS also follows these technical developments . This is the comprehensive regulation of long-haul flights with two- and three-engine aircraft.

As a result, the Airbus 340 is no longer used as frequently, and as four-engine civil aircraft, the Boeing 747 and Airbus 380 will in future mainly take off and land at airports around the world for whose size class there is no twin-engine alternative.

A niche for four-engine aircraft will probably initially be private, non-commercial aircraft operations (e.g. luxury travel aircraft) and long-haul operations of newly established airlines. For example, private jets do not receive ETOPS approval from the FAA . Even airlines that have not proven sufficient experience in the operation of long-haul aircraft do not necessarily receive ETOPS approval immediately after starting operations. For this reason, z. For example, the Tahitian airline Air Tahiti Nui only uses the A340-300: At the start of operations at the end of 1998, there was no ETOPS approval and the Airbus A340 was the only model for the young company that it could use in its route network, which only consisted of long-haul transoceanic routes . In addition, there are still routes in the South Pacific that can only be flown with three- and four-engine aircraft, e.g. B. Auckland - Santiago de Chile .

Since 2007, Kawasaki Heavy Industries has been developing the four - engine XP-1 as a marine surveillance aircraft for the Japanese Sea Self-Defense Forces .

Design features

Boeing 747-400: Engines under the wings

Engines below the wings

Four turbofan engines mounted in pairs in engine nacelles below the wings provide the necessary thrust . This arrangement has largely prevailed for commercial aircraft today.

Although disadvantages in terms of controllability during engine failures, the risk of foreign objects being sucked in and cabin noise are accepted, the advantages in terms of fuel consumption and maintenance costs outweigh this.

Engines on the side of the stern

IL-62: stern engines

The engines are attached on both sides at the end of the fuselage in engine nacelles (for example with Vickers VC-10 or Ilyushin Il-62 ), mostly with spacers. This arrangement requires the design of the horizontal tail unit as a T-shaped tail unit.

It is an advantage to be able to construct aerodynamically very "clean" wings, in which the air flow is not disturbed by engines and their suspensions. In addition, the ground clearance is not dictated by the dimensions of the drooping engines, and the risk of engine damage due to the suction of foreign objects is massively reduced, since the air inlets are very high above the ground.

If one of the engines fails, the aircraft is much easier to control because the lever arm of the loss of thrust is extremely short.

Due to the arrangement close to the fuselage, the noise level in the rear passenger area is somewhat higher, but extremely low in most of the cabin.

A significant disadvantage is the comparatively poor accessibility of the engines for control and maintenance purposes.

Integration of the engines into the wings

DH Comet: engines in the wing root

In the first jet-propelled airliner, the De Havilland DH.106 Comet , the engines were installed in pairs in the wing roots.

If one of the engines fails, the aircraft is much easier to control because the lever arm of the loss of thrust is extremely short. This in turn allowed the use of a relatively small and thus lighter fin.

The risk of engine damage due to the suction of foreign objects is reduced as the air inlets are relatively high above the ground.

A disadvantage is the necessary and weight-intensive structural reinforcement in the wings in order to ensure the stability of the wings even in the event of an engine explosion.

Advantages and disadvantages

Four-engined aircraft are characterized by better take-off properties than aircraft with fewer engines and are not subject to any restrictions with regard to route guidance by ETOPS . However, fuel consumption and, above all, maintenance costs are higher in four-engine aircraft because of the larger number of engines.

The thrust of three engines must be sufficient to operate safely if one engine fails. In contrast to twin-engine airplanes, the engines can be used at a higher capacity (about 3/4 of the maximum) and thus operated closer to the optimal operating point.

For a long time, four engines were associated with long-haul safety. This also explains the advertising slogan of the British airline Virgin Atlantic Airways " 4 Engines 4 long-haul ", which until the delivery of the twin-engine Boeing 787 in October 2014 had only operated four-engine Boeing 747 and Airbus 340.

The engines are generally somewhat smaller than in twin-engine aircraft and, taken as a whole, lead to higher fuel consumption per passenger-kilometer , although this no longer has such a strong impact due to modern developments. The ratio of passenger kilometers to fuel consumption is generally increasing in modern four-engine wide-body aircraft compared to earlier models (military models are not taken into account).

Classification of four-engine aircraft with primarily civil use according to use, dimensions and production

Note on the table: For a quick overview, the aircraft types used in 2012 are highlighted in light blue. The columns can be sorted by clicking the small arrows in the heading bar.

Aircraft type	image	Production (period)	Piece production (2012)	Piece ready for use (2012)	country	Length (from – to) in m	Span (from – to) in m	Range in km	Starting weight in t	comment
Airbus A340 -200 / -300 / -500 / -600		1991-2011	377	362	France / Germany / European consortium	59-75 m	60-63 m	14,600 km	365 t	A340-600 replaced by Boeing 747-8 as the longest aircraft in the world
Airbus A380 -800		2005–	97	97	France / Germany / European consortium	72 m	79 m	14,800 km	560 t	A380-900 (79 m length) and freighter A380-800F currently frozen
Antonov An-124 Ruslan / Condor		1982–1992, since 2008	57+	25th	Ukraine (former Soviet Union )	69 m	73 m	4,800 km	392 t	Wide-body transport aircraft, initially used in the military
Avro 706 Ashton		1950s	6th	-	United Kingdom	26-30 m	26 m	2,700 km	37 t	Prototypes
Avro Canada C-102 jetliner		1949	1	-	United Kingdom / Canada	25 m	30 m	2,000 km	30 t	prototype
Avro RJ family (RJ85, RJ100, BAe 146)		1981-2003	387	183	United Kingdom	26-30 m	26 m	2,800 km	46 t	only four-engine short- and medium-haul aircraft
152 / Baade B-152 / Dresden 152 / VL-DDR 152		1958-1961	3	-	German Democratic Republic	31 m	26 m	2,400 km	46 t	Prototypes, the only jet aircraft development in the GDR
Beriev Be-42 / A-40 Albatros / Mermaid		1980s	2	2	Russia (former Soviet Union )	46 m	42 m	5,500 km	86 t	world's largest amphibious aircraft, originally for military use
Boeing 707		1957-1979	1.010	2	United States	44-46 m	40-44 m	9,700 km	150 t	first long-haul aircraft equipped with jet engines
Boeing 720		1957-1967	154	-	United States	41 m	40 m	6,700 km	106 t	Short to medium haul variant (originally: Boeing 707-020)
Boeing 747 -100 / -200 / -300 Jumbo Jet ( Classic series)		1969-1991	675	80	United States	71 m	60 m	13,000 km	374 t	no longer in production
Boeing 747-123 Shuttle Carrier Aircraft (SCA)		1975 and 1989	2	2	United States	70 m	59 m	1,850 km	322 t	Transport of the NASA space shuttle (approx. 70 t empty weight)
Boeing 747SP Special Performance		1975-1987	45	18 (approx.)	United States	56 m	60 m	15,400 km	317 t	shortened jumbo jet
Boeing 747 -400 / -400F / -8 / -8F Jumbo Jet		1989-	734	605	United States	71-76 m	65-69 m	13,500 km	400 t	Passenger version of the 747-400 no longer in production; 747-8 is currently the longest aircraft in the world
Boeing 747LCF Dreamlifter		2003–	3	3	United States	71 m	65 m	7,800 km	364 t	Wide-body transport aircraft, used in Boeing production
Boeing VC-25A / 25-B (747-200B) Air Force One		1990-1991	2	2	United States	71 m	60 m	13,000 km	375 t	Machines of the President of the USA
Aérospatiale-BAC Concorde 101/102		1962-1976	20th	-	France / United Kingdom	61 m	25 m	7,250 km	190 t	Supersonic airliner in service until 2003
Convair CV-880 Skylark / Golden Arrow		1959-1962	65	-	United States	36 m	39 m	5,000 km	83 t	Jet airliner
Convair CV-990 Coronado		1961-1963	37	-	United States	42 m	36 m	8,700 km	115 t	enlarged version of the Convair CV-880
De Havilland DH.106 Comet 1-4		1951-1964	114	-	United Kingdom	28-35 m	32-35 m	6,900 km	73 t	first jet airliner
Douglas DC-8		1958-1972	556	17th	United States	45-57 m	43-45 m	12,400 km	160 t	one of the first jet passenger aircraft, from 1967 McDonnell Douglas, since 1997 Boeing
Ilyushin Il-62 Classic		1963-1999	292	13	Russia (former Soviet Union )	53 m	43 m	10,000 km	165 t	Long-haul jet of the USSR , all-metal aircraft
Ilyushin Il-76 Candid [civil]		1974–1997, since 2005	560 (approx. Civil)	147	Russia (former Soviet Union )	46-53 m	50 m	6,300 km	210 t	heavy transport and commercial aircraft, civil and military use (see below)
Ilyushin Il-86 Camber		1977-1994	106	4th	Russia (former Soviet Union )	59 m	48 m	5,000 km	206 t	first wide-body aircraft in the Soviet Union
Ilyushin Il-96		1993–	29	13+	Russia	55-63 m	57-60 m	11,000 km	216 t	Wide-body airliner
Lockheed L-1329 JetStar / C-140		1961-1979	204	12 +	United States	16 m	18 m	4,800 km	20 t	also used militarily
McDonnell 119/220		1958	1	-	United States	20 m	17 m	3,800 km	21 t	Inferior competitor to the Lockheed JetStar
Shanghai Y-10		1980	2	-	People's Republic of China	42 m	43 m	8,300 km	110 t	Chinese project of a passenger jet, only one airworthy copy built
Tupolev Tu-144 Charger		1960s – 1978 (approx.)	16	-	Russia (former Soviet Union )	65 m	28 m	6,500 km	207 t	first supersonic airliner, only 7 months in use
White Knight Two (by Scaled Composites )		2008–	1	1	United States	24 m	43 m	5,400 km	45+ t (?)	experimental carrier aircraft for spacecraft SpaceShipTwo

Classification of four-engine aircraft primarily for military use according to size and production

Note on the table: For a quick overview, the aircraft types used in 2012 are highlighted in light blue. The columns can be sorted by clicking the small arrows in the heading bar.

Aircraft type	image	Production (period)	Piece production (2012)	Piece ready for use (2012)	country	Length (from-to) in m	Span (from-to) in m	Range in km	Starting weight in t	comment
Arado Ar 234 C		1945	14th	-	German Empire	12 m	14 m	700 km	10 t	Prototype, approx. 1.5 t payload
Avro Vulcan		1956-1965	136	-	United Kingdom	30 m	34 m	7,400 km	113 t	one of the three so-called V-bombers (Vulcan, Valiant and Victor) of the Royal Air Force
Beriev A-50 Shmel / Mainstay		1984–	40 (approx.)	31 (approx.)	Russia (former Soviet Union )	47 m	50 m	7,300 km	172 t	AEW variant of the Il-76 MD , also incorrectly called Il-82
Boeing 707-320 E-3 Sentry		1974-1991	68	64	United States	46 m	44 m	8,000 km	147 t	AWACS air reconnaissance aircraft
Boeing 707-320 E-6 Mercury		1989-1992	16	16	United States	45 m	45 m	12,100 km	154 t	US Navy combat control platform
Boeing 707-300 E-8 Joint Stars		1988-2005	19th	17th	United States	46 m	44 m	9,300 km	152 t	flying command and control center
Boeing / de Havilland C-8A QSRA		1972	1	-	United States	24 m	30 m		20 t	Prototype for testing the upper surface blowing effect ( Coanda effect )
Boeing C-17 Globemaster III		1991–	250+	246	United States	53 m	51 m	5,100 km	263 t	multifunctional large transport aircraft, payload 77 t
Boeing C-135 Stratolifter / EC-, OC-, RC-, TC-, WC-135		1954-1965	45	29	United States	42 m	40 m	12,000 km	124 t	Transport aircraft , derived from the KC-135 , various special models
Boeing C-137 Stratoliner / C-18		1954-1955	3	-	United States	46 m	44 m	12,000 km	184 t	derived from the Boeing 707 , V-137C was used as Air Force One of the President of the USA
Boeing KC-135 Stratotanker		1954-1991	761	470	United States	42 m	40 m	17,700 km	146 t	Tanker aircraft , payload 92 t of fuel
Boeing RC-135 ELINT		1964-1968	40 (approx.)	22nd	United States	41 m	39 m	6,500 km	134 t	US Air Force reconnaissance aircraft , derived from the KC-135
Boeing Rockwell B-1B Lancer		1970–1988 (approx.)	104	66	United States	44 m	41/23 m	5,500 km	216 t	long-range strategic bomber
British Aerospace Nimrod		1966-1974	62	-	United Kingdom	36-38 m	35 m	9,300 km	87 t	Royal Air Force reconnaissance aircraft until 2011
Convair B-36 D - B-36J Peacemaker		1947-1954	300 (approx.)	-	United States	49 m	70 m	13,000 km	186 t	additional 6 propeller engines
Convair B-58 Hustler		1955-1964	116	-	United States	29 m	17 m	3,200 km	73 t	high speed supersonic bomber
Handley Page Victor		1952-1963	86	-	United Kingdom	36 m	34 m	7,400 km	80 t	one of the three so-called V-bombers (Vulcan, Valiant and Victor) of the Royal Air Force
Ilyushin Il-76 , Il-76M Candid , Il-78 Midas , Il-76MD-90A		1978–	400+ (approx.)	165+ (approx.)	Russia (former Soviet Union )	47-53 m	51 m	6,000 km (approx.)	210 t	IL-76M as a transport and hospital aircraft, IL-78 as a tanker (payload approx. 28 t of fuel), IL-76MD-90A as a modernized version from 2011; also in civil use (see above)
Kawasaki XP-1		2007–	8th	8th	Japan	38 m	35 m	8,000 km	80 t	Prototypes in Eluger trials since 2007
KongJing KJ-2000		2000–	4+ (approx.)	4+ (approx.)	People's Republic of China	46 m	50 m	5,000 km (approx.)	200 t (approx.)	AWACS air reconnaissance aircraft, variant of the Il-76 MD / A-50
Lockheed C-5 Galaxy		1968-1973, 1986-1989	131	73	United States	75 m	67 m	4,400 km	380 t	Wide-body transport aircraft, payload 118 t or 345 soldiers
Lockheed C-141 Starlifter		1963-1968	285	-	United States	44-51 m	48 m	6,500 km	147 t	Transport plane
Martin P6M Sea Master		1955-1959	12	-	United States	41 m	32 m	3,200 km	80 t	originally planned as a nuclear bomber
McDonnell Douglas YC-15		1975-1979	2	-	United States	38 m	33/40 m	4,800 km	98 t	Prototype of a military transporter (in competition with Boeing YC-14 )
Myasishchev M-4 / 3MT Bison		1953-1963	93	-	Soviet Union	48 m	50 m	10,000 km (approx.)	181 t	strategic bomber
Myasishchev M-50 Bounder		1955–1959 (approx.)	2	-	Soviet Union	57 m	35 m	7,400 km	200 t	Prototypes for a supersonic bomber
North American B-45 tornado		1948-1950	143	-	United States	23 m	27 m	1,600 km	37 t	light bomber
Northrop Grumman B-2 Spirit (also: The Stealth Bomber )		1997–	21+	19th	United States	21 m	52 m	18,000 km	152 t	long-range strategic bomber
OK-GLI / BTS-02 (Buran)		1984	1	-	Soviet Union	36 m	24 m	km	105 t	Independent, airworthy model of a Buran space shuttle, flights 1984–1989
Sukhoi T-4 Sotka		1972-1974	4th	-	Russia (former Soviet Union )	44 m	22 m	6,000 km	125 t	Prototypes, never in service
Tupolev Tu-160 Blackjack		1981–1994, 2005–	35+	12+	Russia	54 m	55/35 m	10,000 km	275 t	heavy strategic swing-wing and supersonic bomber
Vickers Valiant		1952-1957	107	-	United Kingdom	33 m	35 m	3,500 km	63 t	one of the three so-called V-bombers (Vulcan, Valiant and Victor) of the Royal Air Force
Vickers VC10 / VC10K / C1 / Super VC10		1962–1970, 1978 – mid-1990s (approx.)	54	6th	United Kingdom	48-52 m	45 m	6,300-11,000 km	150 t	one of the first long-haul aircraft, mainly in the military variant VC10K / C1 in use as Transport and refueling aircraft of the Royal Air Force
Xian Y-20 / Yun-20		2012–	2	2	People's Republic of China	47 m (approx.)	50 m (approx.)	4,400 km (approx.)	220 t	Strategic transporter , new development, prototypes in flight test

See also

• Single-engine aircraft
• Twin-engine aircraft
• Three-engine aircraft
• Six-engine aircraft
• Eight-engine aircraft

Remarks

1. ↑ ^{a b} The respective model is classified under the name under which it became known or, in the case of current models, under which it is currently offered or listed by the manufacturers. Possibly. Several names are listed, for models from the former Soviet Union, Russia, China, etc. also the NATO names. For some models there is no entry in the German-language Wikipedia, in these cases there is a direct link to the English Wikipedia.
2. ↑ ^{a b c d} The numbers are taken from (a) overviews in Flight International : "World Airliner Census" for civil aircraft (as of mid-year), "Directory World Air Forces" for military aircraft (as of end of year). The overviews summarize all aircraft in use on the respective cut-off date, including temporarily decommissioned ("parked") aircraft, with the exception of aircraft operated by leasing companies. (b) Airbus production information at www.airbus.com (always updated) under Aircraft families and Boeing at www.boeing.com . Some of the total number of items produced are not published. B. the engl. Taken from Wikipedia or other statistics from Flight International and Aviation Week . The overviews are online at Flightglobal. Archived from the original ; accessed on March 23, 2020 .  available as PDF. Figures for China are generally not certain. a. sinodefence.com .
3. ↑ ^{a b} Country or countries with the registered office of the manufacturer company or companies. In cooperation, e.g. B. EADS / Airbus all countries directly involved are listed. In the case of the countries of the former Eastern Bloc , the former USSR may also be listed for production before 1990.
4. ↑ ^{a b c d} The length and span dimensions are rounded to the nearest meter in order to keep the table clear. Different sizes for variants of a model: from – to m, for swing-wing aircraft : maximum / minimum size.
5. ↑ ^{a b} The manufacturer than normally maximum specified range in kilometers when in normal payload, most powerful model of the type without consideration of additional tanks, except possibly at specifically mentioned ER models ( extended range rounded = extended range) in kilometers, optionally
6. ↑ ^{a b} Gross weight, according to manufacturer information in metric tons, most powerful model of the type, possibly rounded, military models including weapon load.
7. ↑ further information at aerofiles.com : "QSRA 1978 =" Quiet Short-haul Research Aircraft "airliner developed by NASA-Ames from de Havilland DHC-5 / C-8A [63-13687] and modified by Boeing with four 7500 # Lycoming YF102 turbofans, new wing and tail. Employed upper surface blowing powered lift technology over inboard Coanda flaps and boundary layer control air over the wing's leading edges and ailerons; ff: 7/6/78. In a joint test program with USN it made 37 touch-and-go and 16 full-stop landings and take-offs from USS Kitty Hawk on 7/10/80. "

Individual evidence

1. ↑ Market analysis for four-engine jets at airliners.de
2. ^ Report from EADS
3. ↑ The A380-800 - The new dimension of flying. Dr. Peters Group, January 23, 2008; archived from the original on March 12, 2016 ; accessed on September 3, 2013 (consumption data of the A380). 
4. ↑ of which Avro RJ: 166; BAe 146: 221
5. ↑ Description of the four engines at Globalsecurity as the two main engines and two sustainer engines ... established on the pylons above the landing-gear fairings after the wing with a drawing
6. ↑ Statistics on the Boeing 720 at Aviastar
7. ↑ For details on production, see the Boeing website , accessed on January 27, 2013
8. ↑ Type -100: 205 copies, -200: 316 copies, -300: 81 copies, freighter -200F: 73 copies, without 747-SP
9. ↑ according to flightglobal.com type -100: 1 copy, -200: 58 copies, -300: 21 copies, status: autumn 2012
10. ↑ Production overview (English)
11. ↑ continuously updated overview of the models in service (English), accessed on January 27, 2013
12. ↑ including according to boeing.com model -400: 532 copies, -8:; Freighter -400F: 166, -8F: 28 copies, as of December 2012
13. ↑ according to flightglobal.com as of autumn 2012: 8 in civil use, 5 in military use
14. ↑ In total, around 960 machines of the types Il-76 / Il-78 were produced by 2010, of which approx. 560 for civil use and approx. 400 for military use
15. ↑ At the end of 2012 in the civilian sector in Africa 21, Asia 24, Europe 102
16. ↑ in military use for special missions
17. ↑ at airliners.net a dozen are for 2012 min. Still in use copies located listed (VP-CSM, 62-4197, N159B, ZS-ICC, 61-2489, etc.)
18. ↑ Another photo of an Ar 234C at Airventure (Ger.)
19. ↑ Sources: Hans-Jürgen Becker, NASA aviation research and groundbreaking developments, Stuttgart, 2005, pp. 101–103 (The test programs C-8A AWJSRA and QRSA)
20. ↑ in 2009 as special models 2 OC-135, 22 RC-135, 3 TC-135 and 2 WC-135
21. ↑ a total of at least 1,000 machines of the types IL-76 / IL-78 were produced up to 2012, of which over 560 for civilian use and over 440 for military use
22. ↑ Information from the Flug-Revue ( Memento from March 7, 2009 in the Internet Archive )
23. ↑ Type description of the KJ-2000 (English), accessed on January 27, 2013
24. ↑ more photos at chinesemilitaryreview , accessed on January 27, 2012
25. ↑ for more information see Buran, Technik Museum Speyer, Speyer 2008, ISBN 3-9809437-7-1
26. ↑ more photos at defenseindustrydaily.com  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.  
27. ↑ Decommissioning planned for autumn 2013, frequently updated overview of the models in use at vc10.net , information on retrofitting at defenseindustrydaily.com , both sources in English, accessed on January 30, 2013
28. ↑ s. britains-smallwars.com ( Memento of February 4, 2007 in the Internet Archive )
29. ↑ Chinese Y-20 revealed in new online pictures. Flightglobal, December 27, 2012, accessed January 10, 2013 .