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VFW VAK 191B

August 21, 2023

The VFW VAK 191B was an experimental German vertical take-off and landing (VTOL) strike fighter of the early 1970s. VAK was the abbreviation for Vertikalstartendes Aufklärungs- und Kampfflugzeug (Vertical Take-off Reconnaissance and Strike Aircraft). Designed and built by the Vereinigte Flugtechnische Werke (VFW), it was developed with the purpose of eventually serving as a replacement for the Italian Fiat G.91 then in service with the German Air Force. Operationally, it was intended to have been armed with nuclear weapons as a deterrent against aggression from the Soviet Union and, in the event of a major war breaking out, to survive the first wave of attacks by deploying to dispersed locations, rather than conventional airfields, and to retaliate against targets behind enemy lines.

VAK 191B
VAK 191B displayed next to a Dornier Do 31 transport
Role VTOL strike fighter
Manufacturer Vereinigte Flugtechnische Werke
First flight 10 September 1971[1]
Status Retired
Primary user German Air Force
Number built 3

The VAK 191B suffered from a protracted development cycle, spanning ten years between inception and flight, in part due to changing requirements, changing partnerships and the difficulties inherent in the development of VTOL-capable aircraft. Ultimately, during the late 1960s, VFW took the decision to demote the development programme from targeting the type's production and instead only to test-fly a limited number of prototypes, using the VAK 191B effectively as a technology demonstrator and experimental aircraft to support the company's other activities and future programmes. On 10 September 1971, the first prototype conducted the type's maiden flight. A total of 91 flights were performed prior to the retirement of all three prototypes in 1975. These aircraft have been preserved and two are now on public display in museums.

Design and development

Background

During the 1950s, rapid advances in the field of jet propulsion, particularly in terms of increased thrust and compact engine units, had contributed to an increased belief in the technical viability of vertical takeoff/landing (VTOL) aircraft, particularly within Western Europe and the United States.[2] During 1950s and 1960s, multiple programmes in Britain, France, and the United States were initiated; likewise, aviation companies inside West Germany were keen not to be left out of this emerging technology. Shortly after 1957, the year in which the post-Second World War ban upon West Germany operating and developing combat aircraft was lifted, German aviation firms Dornier Flugzeugwerke, Heinkel, and Messerschmitt, having also been allowed to resume their own activities that same year, received an official request from the German Federal Government that urged them to perform investigative work on the topic of VTOL aircraft and to produce concept designs.[3]

As such, multiple companies commenced work on their own conceptual designs for VTOL-capable interceptor aircraft; in order for these designs to be operationally relevant and viable, it was recognised that it would be necessary for the flight performance to equal that of conventional interceptors of the era, such as the contemporary Lockheed F-104G Starfighter.[4] Over time, two separate and distinct requirements emerged, one calling for a VTOL-capable successor to the F-104G interceptor while the other sought a VTOL successor to the Italian Fiat G.91 ground-attack fighter. According to aerospace publication Flight International, this call for a Fiat G.91 replacement, which came under a NATO requirement, known as NBMR-3, was a crucial trigger and greatly influenced the development programme that would lead to the VAK 191B.[1]

In conjunction with these requirements being on offer, Germany's Federal Ministry of Defence (BMVg) championed for the merger of the competing companies; it deliberately withheld the issuing of a development contract in order to incentivise companies to undertake such activities.[5] As such, during September 1961, a new German aircraft company, known as Vereinigte Flugtechnische Werke (VFW), was formed as joint venture between Focke-Wulf and Weser Flugzeugbau, to develop its own VTOL strike aircraft.[6] Initially, Italian aircraft manufacturer Fiat was also a participating company in VFW, however, Italy later chose to withdraw from the joint development agreement with Germany during 1967. Despite this decision, Fiat remained as a major sub-contractor for the venture, being responsible for the production of various structural elements such as wings, tailplanes and some of the fuselage.[7]

Concept and definition

 
Rotating nozzle detail

The VAK 191B was similar in concept to the British Harrier jump jet, but was designed for a supersonic dash capability (Mach number 1.2–1.4) at medium to high altitudes.[1] It was judged that having a single engine would create too much drag, but the two lift engines were dead weight in cruise, and the small cruise engine gave a poor thrust to weight ratio. The VAK 191B had been provided with relatively small and highly loaded wings. By contrast, the Harrier possessed a significantly higher thrust-to-weight ratio, it was effective as a dogfighter, and had larger wings which were put to good use when performing rolling short takeoffs.

The choice of lift/propulsion system was an obvious critical element of the aircraft's design.[1] According to Flight International, there were several options available in the field of vectored thrust propulsion during its development, these being the twin-nozzle Rolls-Royce/MAN Turbo RB153 and the four-nozzle Bristol Siddeley BS.94 engines.[8] Ultimately, VFW's design team decided to adopt the Rolls-Royce/MAN Turbo RB.193-12 engine to provide both lift and cruise, which was augmented by a pair of Rolls-Royce vertical lift engines. In practice, this arrangement meant during vertical hover, all of the lifting thrust could either be generated by the propulsion engine, or entirely produced by the two lift engines, or some combination thereof; analysis determined that the optimum thrust-generation configuration would be a 50–50 split between both engine types.[9]

During mid-1963, the in-development aircraft received its design designation of VAK 191B. Reportedly, the initials in this designation stood for Vertikalstartendes Aufklärungs-und Kampfflugzeug (in English: vertical take-off reconnaissance and fighter aircraft), the numbers were to indicate its role as a successor to the Fiat G.91, while the B suffix was to show that the aircraft was the second of the four designs to be studied for this purpose.[9] The rate of progress on the programme was noticeably slow; ten years passed between its inception and the first prototype performing its maiden flight on 10 September 1971.[1] The slow progression can be viewed as a natural result of specification changes, such as a revised operational requirement that called for the aircraft to possess greater manoeuvrability issued during 1965.

Scaling-back and termination

Even prior to the first flight of the type, the programme had been heavily affected by political changes. Amongst these were the effective irrelevance of the original NBMR-3 requirement and the decreasing importance of the strike mission as a result of a German government decision to abandon the nuclear role, a divergence of opinion between partner countries, the withdrawal of the Italian government from participation during August 1967, and a growing awareness of the programme's escalating costs.[7] At one stage, the Italian government had agreed to take on 40 per cent of the programme's development costs, thus their departure meant that a substantial amount of funding was lost for the venture.[9]

The emergence of a new German/American "Advanced Vertical Strike" (AVS) programme also played a role in diminishing the type's perceived value; the prospective aircraft which was on offer from the Americans via a cooperative venture with Germany had somewhat eclipsed the VAK 191B in the eyes of the German Air Force and served to effectively undermine support for the programme. Finally, during 1968, officials at VFW decided that the VAK 191B should be reclassified as an experimental programme, and that the resultant aircraft should principally function only as technology demonstrators instead.[6] The initial programme had called for the construction of three single-seater and three two-seater aircraft; however, amid escalating costs, this intended test batch was first converted to become six single-seat aircraft, and was later on cut down to only involve three single-seat aircraft following Italy's withdrawal.[7]

During April 1969, the first prototype was rolled out at VFW's facility in Bremen, and was later displayed at that year's Hannover Air Show.[10] Over the course of the following 17 months, it went through a flight-qualification programme, during which some issues were discovered, most of these associated with the hydraulic system. During February 1971, trials commenced using the cruise engine for the first time.[10] The first hovering flight performed by the VAK 191B was conducted at Bremen on 20 September 1971.[1]

A total of three VAK 191B aircraft were flown in the flight test program, which was conducted between 1970 and 1975, during which a total of 91 flights were performed. The first transition from vertical flight to horizontal and vice versa was achieved on 26 October 1972 in Munich. At one stage, the prototypes were used for testing some of the concepts that were then being considered for the European MRCA programme (which led to the Panavia Tornado strike fighter), including the use of fly-by-wire technology. According to Flight International, the VAK 191B was well-suited to this purpose due to its modern flight-control system and its general characteristics.[10]

Surviving aircraft

Operators

  Germany

Specifications (VAK 191B)

 
VAK 191B from above

Data from X-Planes and Prototypes[14]

General characteristics

  • Crew: 1
  • Length: 16.4 m (53 ft 10 in)
  • Wingspan: 6.16 m (20 ft 3 in)
  • Height: 4.3 m (14 ft 1 in)
  • Wing area: 19 m2 (200 sq ft)
  • Airfoil: root: NACA 63A005; tip: NACA 65A006[15]
  • Empty weight: 5,562 kg (12,262 lb)
  • Gross weight: 8,507 kg (18,755 lb)
  • Max takeoff weight: 9,000 kg (19,842 lb)
  • Powerplant: 1 × Rolls-Royce/MAN Turbo RB193-12 vectored-thrust turbofan engine, 45.2 kN (10,200 lbf) thrust for lift/cruise
  • Powerplant: 2 × Rolls-Royce RB162-81F-08 turbojet, 26.5 kN (6,000 lbf) thrust each for lift

Performance

  • Maximum speed: 1,108 km/h (688 mph, 598 kn)
  • Range: 400 km (250 mi, 220 nmi)
  • Service ceiling: 15,000 m (49,000 ft)

See also

Aircraft of comparable role, configuration, and era

Related lists

References

Citations

  1. ^ a b c d e f Flight International 1972, p. 502.
  2. ^ Hirschel, Prem and Madelung 2012, p. 451.
  3. ^ Hirschel, Prem and Madelung 2012, pp. 451–452.
  4. ^ Hirschel, Prem and Madelung 2012, p. 452.
  5. ^ Hirschel, Prem and Madelung 2012, pp. 583–584.
  6. ^ a b Flight International 1972, pp. 502, 504.
  7. ^ a b c Flight International 1972, p. 504.
  8. ^ Flight International 1972, pp. 502–503.
  9. ^ a b c Flight International 1972, p. 503.
  10. ^ a b c Flight International 1972, p. 505.
  11. ^ "Deutsches Museum Flugwerft Schleissheim Oberschleißheim, Germany". Aviationmuseum. Retrieved 31 October 2019.
  12. ^ "Wehrtechnische Studiensammlung Koblenz, Germany - www.aviationmuseum.eu". Aviationmuseum. Retrieved 31 October 2019.
  13. ^ Jackson,1976. p.144.
  14. ^ Winchester, Jim, X-Planes and prototypes, Barnes & Noble
  15. ^ Lednicer, David. "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu. Retrieved 16 April 2019.

Bibliography

  • Buttler, Tony and Jean-Louis Delezenne. X-Planes of Europe: Secret Research Aircraft from the Golden Age 1946-1974. Manchester, UK: Hikoki Publications, 2012. ISBN 978-1-902-10921-3
  • Hirschel, Ernst Heinrich., Horst Prem and Gero Madelung. Aeronautical Research in Germany: From Lilienthal until Today. Springer Science & Business Media, 2012. ISBN 3-642-18484-7.
  • Jackson, Paul A. German Military Aviation 1956–1976. Hinckley, Leicestershire, UK: Midland Counties Publications, 1976. ISBN 0-904597-03-2.
  • Wilson 'The Technical Editor', Michael (13 April 1972), "VAK 191B—Germany's V/Stol fighter?", Flight International, IPC Business, 101 (3292): 502–506 {{citation}}: |last= has generic name (help)

External links

 
Wikimedia Commons has media related to VAK191.
  • Paul Nann, Photo of VAK191B
  • Photo of lineup of three VAK 191Bs
  • VAK 191B (French language)

August 21, 2023
191b, experimental, german, vertical, take, landing, vtol, strike, fighter, early, 1970s, abbreviation, vertikalstartendes, aufklärungs, kampfflugzeug, vertical, take, reconnaissance, strike, aircraft, designed, built, vereinigte, flugtechnische, werke, develo. The VFW VAK 191B was an experimental German vertical take off and landing VTOL strike fighter of the early 1970s VAK was the abbreviation for Vertikalstartendes Aufklarungs und Kampfflugzeug Vertical Take off Reconnaissance and Strike Aircraft Designed and built by the Vereinigte Flugtechnische Werke VFW it was developed with the purpose of eventually serving as a replacement for the Italian Fiat G 91 then in service with the German Air Force Operationally it was intended to have been armed with nuclear weapons as a deterrent against aggression from the Soviet Union and in the event of a major war breaking out to survive the first wave of attacks by deploying to dispersed locations rather than conventional airfields and to retaliate against targets behind enemy lines VAK 191BVAK 191B displayed next to a Dornier Do 31 transportRole VTOL strike fighterManufacturer Vereinigte Flugtechnische WerkeFirst flight 10 September 1971 1 Status RetiredPrimary user German Air ForceNumber built 3The VAK 191B suffered from a protracted development cycle spanning ten years between inception and flight in part due to changing requirements changing partnerships and the difficulties inherent in the development of VTOL capable aircraft Ultimately during the late 1960s VFW took the decision to demote the development programme from targeting the type s production and instead only to test fly a limited number of prototypes using the VAK 191B effectively as a technology demonstrator and experimental aircraft to support the company s other activities and future programmes On 10 September 1971 the first prototype conducted the type s maiden flight A total of 91 flights were performed prior to the retirement of all three prototypes in 1975 These aircraft have been preserved and two are now on public display in museums Contents 1 Design and development 1 1 Background 1 2 Concept and definition 1 3 Scaling back and termination 2 Surviving aircraft 3 Operators 4 Specifications VAK 191B 5 See also 6 References 6 1 Citations 6 2 Bibliography 7 External linksDesign and development EditBackground Edit During the 1950s rapid advances in the field of jet propulsion particularly in terms of increased thrust and compact engine units had contributed to an increased belief in the technical viability of vertical takeoff landing VTOL aircraft particularly within Western Europe and the United States 2 During 1950s and 1960s multiple programmes in Britain France and the United States were initiated likewise aviation companies inside West Germany were keen not to be left out of this emerging technology Shortly after 1957 the year in which the post Second World War ban upon West Germany operating and developing combat aircraft was lifted German aviation firms Dornier Flugzeugwerke Heinkel and Messerschmitt having also been allowed to resume their own activities that same year received an official request from the German Federal Government that urged them to perform investigative work on the topic of VTOL aircraft and to produce concept designs 3 As such multiple companies commenced work on their own conceptual designs for VTOL capable interceptor aircraft in order for these designs to be operationally relevant and viable it was recognised that it would be necessary for the flight performance to equal that of conventional interceptors of the era such as the contemporary Lockheed F 104G Starfighter 4 Over time two separate and distinct requirements emerged one calling for a VTOL capable successor to the F 104G interceptor while the other sought a VTOL successor to the Italian Fiat G 91 ground attack fighter According to aerospace publication Flight International this call for a Fiat G 91 replacement which came under a NATO requirement known as NBMR 3 was a crucial trigger and greatly influenced the development programme that would lead to the VAK 191B 1 In conjunction with these requirements being on offer Germany s Federal Ministry of Defence BMVg championed for the merger of the competing companies it deliberately withheld the issuing of a development contract in order to incentivise companies to undertake such activities 5 As such during September 1961 a new German aircraft company known as Vereinigte Flugtechnische Werke VFW was formed as joint venture between Focke Wulf and Weser Flugzeugbau to develop its own VTOL strike aircraft 6 Initially Italian aircraft manufacturer Fiat was also a participating company in VFW however Italy later chose to withdraw from the joint development agreement with Germany during 1967 Despite this decision Fiat remained as a major sub contractor for the venture being responsible for the production of various structural elements such as wings tailplanes and some of the fuselage 7 Concept and definition Edit Rotating nozzle detailThe VAK 191B was similar in concept to the British Harrier jump jet but was designed for a supersonic dash capability Mach number 1 2 1 4 at medium to high altitudes 1 It was judged that having a single engine would create too much drag but the two lift engines were dead weight in cruise and the small cruise engine gave a poor thrust to weight ratio The VAK 191B had been provided with relatively small and highly loaded wings By contrast the Harrier possessed a significantly higher thrust to weight ratio it was effective as a dogfighter and had larger wings which were put to good use when performing rolling short takeoffs The choice of lift propulsion system was an obvious critical element of the aircraft s design 1 According to Flight International there were several options available in the field of vectored thrust propulsion during its development these being the twin nozzle Rolls Royce MAN Turbo RB153 and the four nozzle Bristol Siddeley BS 94 engines 8 Ultimately VFW s design team decided to adopt the Rolls Royce MAN Turbo RB 193 12 engine to provide both lift and cruise which was augmented by a pair of Rolls Royce vertical lift engines In practice this arrangement meant during vertical hover all of the lifting thrust could either be generated by the propulsion engine or entirely produced by the two lift engines or some combination thereof analysis determined that the optimum thrust generation configuration would be a 50 50 split between both engine types 9 During mid 1963 the in development aircraft received its design designation of VAK 191B Reportedly the initials in this designation stood for Vertikalstartendes Aufklarungs und Kampfflugzeug in English vertical take off reconnaissance and fighter aircraft the numbers were to indicate its role as a successor to the Fiat G 91 while the B suffix was to show that the aircraft was the second of the four designs to be studied for this purpose 9 The rate of progress on the programme was noticeably slow ten years passed between its inception and the first prototype performing its maiden flight on 10 September 1971 1 The slow progression can be viewed as a natural result of specification changes such as a revised operational requirement that called for the aircraft to possess greater manoeuvrability issued during 1965 Scaling back and termination Edit Even prior to the first flight of the type the programme had been heavily affected by political changes Amongst these were the effective irrelevance of the original NBMR 3 requirement and the decreasing importance of the strike mission as a result of a German government decision to abandon the nuclear role a divergence of opinion between partner countries the withdrawal of the Italian government from participation during August 1967 and a growing awareness of the programme s escalating costs 7 At one stage the Italian government had agreed to take on 40 per cent of the programme s development costs thus their departure meant that a substantial amount of funding was lost for the venture 9 The emergence of a new German American Advanced Vertical Strike AVS programme also played a role in diminishing the type s perceived value the prospective aircraft which was on offer from the Americans via a cooperative venture with Germany had somewhat eclipsed the VAK 191B in the eyes of the German Air Force and served to effectively undermine support for the programme Finally during 1968 officials at VFW decided that the VAK 191B should be reclassified as an experimental programme and that the resultant aircraft should principally function only as technology demonstrators instead 6 The initial programme had called for the construction of three single seater and three two seater aircraft however amid escalating costs this intended test batch was first converted to become six single seat aircraft and was later on cut down to only involve three single seat aircraft following Italy s withdrawal 7 During April 1969 the first prototype was rolled out at VFW s facility in Bremen and was later displayed at that year s Hannover Air Show 10 Over the course of the following 17 months it went through a flight qualification programme during which some issues were discovered most of these associated with the hydraulic system During February 1971 trials commenced using the cruise engine for the first time 10 The first hovering flight performed by the VAK 191B was conducted at Bremen on 20 September 1971 1 A total of three VAK 191B aircraft were flown in the flight test program which was conducted between 1970 and 1975 during which a total of 91 flights were performed The first transition from vertical flight to horizontal and vice versa was achieved on 26 October 1972 in Munich At one stage the prototypes were used for testing some of the concepts that were then being considered for the European MRCA programme which led to the Panavia Tornado strike fighter including the use of fly by wire technology According to Flight International the VAK 191B was well suited to this purpose due to its modern flight control system and its general characteristics 10 Surviving aircraft EditAn example of the VAK 191B can be seen at the Deutsches Museum Flugwerft Schleissheim at Oberschleissheim near Munich 11 The second remaining VAK 191B is part of the Wehrtechnische Studiensammlung Military technical collection at Koblenz Germany 12 The third VAK 191B was reported as being put into storage in 1976 13 Its current location is at Airbus in Bremen citation needed Operators Edit GermanyGerman Air Force Luftwaffe citation needed Specifications VAK 191B Edit VAK 191B from aboveData from X Planes and Prototypes 14 General characteristicsCrew 1 Length 16 4 m 53 ft 10 in Wingspan 6 16 m 20 ft 3 in Height 4 3 m 14 ft 1 in Wing area 19 m2 200 sq ft Airfoil root NACA 63A005 tip NACA 65A006 15 Empty weight 5 562 kg 12 262 lb Gross weight 8 507 kg 18 755 lb Max takeoff weight 9 000 kg 19 842 lb Powerplant 1 Rolls Royce MAN Turbo RB193 12 vectored thrust turbofan engine 45 2 kN 10 200 lbf thrust for lift cruise Powerplant 2 Rolls Royce RB162 81F 08 turbojet 26 5 kN 6 000 lbf thrust each for liftPerformance Maximum speed 1 108 km h 688 mph 598 kn Range 400 km 250 mi 220 nmi Service ceiling 15 000 m 49 000 ft See also EditAircraft of comparable role configuration and era EWR VJ 101 Hawker Siddeley Harrier Hawker Siddeley P 1127 Hawker Siddeley P 1154 Yakovlev Yak 38Related lists List of fighter aircraft List of military aircraft of GermanyReferences EditCitations Edit a b c d e f Flight International 1972 p 502 Hirschel Prem and Madelung 2012 p 451 Hirschel Prem and Madelung 2012 pp 451 452 Hirschel Prem and Madelung 2012 p 452 Hirschel Prem and Madelung 2012 pp 583 584 a b Flight International 1972 pp 502 504 a b c Flight International 1972 p 504 Flight International 1972 pp 502 503 a b c Flight International 1972 p 503 a b c Flight International 1972 p 505 Deutsches Museum Flugwerft Schleissheim Oberschleissheim Germany Aviationmuseum Retrieved 31 October 2019 Wehrtechnische Studiensammlung Koblenz Germany www aviationmuseum eu Aviationmuseum Retrieved 31 October 2019 Jackson 1976 p 144 Winchester Jim X Planes and prototypes Barnes amp Noble Lednicer David The Incomplete Guide to Airfoil Usage m selig ae illinois edu Retrieved 16 April 2019 Bibliography Edit Buttler Tony and Jean Louis Delezenne X Planes of Europe Secret Research Aircraft from the Golden Age 1946 1974 Manchester UK Hikoki Publications 2012 ISBN 978 1 902 10921 3 Hirschel Ernst Heinrich Horst Prem and Gero Madelung Aeronautical Research in Germany From Lilienthal until Today Springer Science amp Business Media 2012 ISBN 3 642 18484 7 Jackson Paul A German Military Aviation 1956 1976 Hinckley Leicestershire UK Midland Counties Publications 1976 ISBN 0 904597 03 2 Wilson The Technical Editor Michael 13 April 1972 VAK 191B Germany s V Stol fighter Flight International IPC Business 101 3292 502 506 a href Template Citation html title Template Citation citation a last has generic name help External links Edit Wikimedia Commons has media related to VAK191 Paul Nann Photo of VAK191B Photo of lineup of three VAK 191Bs VAK 191B French language V STOL Fighter Programs in Germany 1956 1975 Retrieved from https en wikipedia org w index php title VFW VAK 191B amp oldid 1118822520, wikipedia, wiki, book, books, library,

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