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NBMR-3 V/STOL fighter (1961)
(NATO Basic Military Requirement)

AC.169a Mach 2 V/STOL fighter
FranceDassaultMirage IIIV
NetherlandsFokker-Republic D.24 Alliance
UKBAC/Vickers 583
UKBAC/Vickers 584
UKBAC/Vickers 585
UKBAC/English ElectricP.39
UKHawker P.1150/3
UKHawker P.1154
AC.169b subsonic V/STOL fighter-bomber
FranceBreguet Br.122
FranceNord N.4400
GermanyEWR VJ.101
GermanyFocke-Wulf FW.1262
ItalyFiatG95/4
UKArmstrong-Whitworth AW.406
UKShorts PD.45
UKShorts PD.49
UKShorts PD.56
UKBAC/English-Electric P.39
USALockheed CL-704
Vertikal Startendes Augklarungs-und-Kampflugzeug
(vertical take-off and landing fighter aircraft)
UKVAK-191AHarrier P.1170 mod
GermanyVAK-191BFocke Wulf FW-1262
GermanyVAK-191CEWR-340 (VJ-101D)
ItalyVAK-191DFiat G.95-4
At least by 1960 it was increasingly clear that a Soviet nuclear attack could close NATO airfields, and destroy its nuclear facilities and the high-performance aircraft, giving the Soviets air superiority from the outset of the war. This required NATO to develop aircraft that could take off from rough unprepared airstrips, and but obviously there must be some aircraft to take the necessary equipment, ammunition and petrol to these advanced fields. After study of their needs, the military authorities of NATO defined three general types of V/STOL aircraft answering to the NBMR (NATO Basic Military Requirement) 3, 4 and 22. Work groups were created to examine the possibility of manufacture of joint prototypes. The NATO 1961 VSTOL competition was in two parts: submissions for a general-purpose transport have to be made by 15 November 1961; submissions for a strike and reconnaissance aircraft must be completed by 31 December 1961.

Designation of the strike aircraft competition is BMR-3, which stands for Basic Military Requirement. Manufacturers were left to decide for themselves whether to employ lift/thrust engines or composite propulsion (separate lift and propulsion engines, probably with full deflection on the latter). BMR-3 stipulated a minimum sea-level speed of Mach 0.92, but it was clear that contenders are expected to do better.

Group AC/169 on the V/STOL attack and reconnaissance plane was equipped with the mandate stated in the document AC/74-D/453. The following countries took part in its work: Germany, Belgium, Canada, France, Italy, Netherlands, the United Kingdom and the United States (Greece in 1961). In July 1960, for the first meeting of the AC/169 group, the Permanent group published the NBMR-3, based on an operational need relating to an improved version of a light attack and and reconnaissance plane with V/STOL capacity intended to replace the FIAT G.91. It was modified to envisage two phases distinct from setting in service, one for 1964/1965, the other for 1966/1967.

On this basis, the group prepared the operational characteristics and technical specifications of the apparatus. In July 1961, an identical letter of the technical specifications (AC/169-IND/1) was sent to more than forty aeronautical manufacturers to invite them to subject preliminary drafts (phase II 1966/1967).

At the instigation of Germany, Commission AC/169(LW) was set up to work on a light attack and reconnaissance VTOL plane. It was equipped with the mandate appearing in the document AC/169-D/20 of December 7, 1961. In addition to Germany, it included four other countries interested by the settling of a light plane - Belgium, Italy, the United Kingdom and the United States. The activities of the commission mainly consisted of information exchanges on the various subjects of study which were entrusted to it.

NATO's Advisory Committee 169 NMBR3 (Nato Military Basic Requirement No 3), a historic document which had great influence on combat aircraft thinking for the next decade. The NMBR3 specification called for a single-seat tactical close-support and reconnaissance fighter to exploit the V/Stol principle, having a combat radius of 250 n.m. at Mach 0-92 and 500 ft altitude while carrying a 2,0001b store. A 5 minute stay in the target area was assumed, with landing reserves of 10 per cent of the initial fuel. Vertical operation was called for at both ends of the mission, with an environment of ISA + 15 C at sea level. Operation from dispersed semi-prepared sites, independent of ground aids, in limited bad weather was also specified. Largely concealed - publicly at any rate - was the nuclear-delivery role, though this dictated the mission requirements and the shape of the aeroplane.

Two months later the committee redefined the objectives, calling for a separate F-104G replacement (the specification for which, AC 169a, was identical with the earlier one) and a successor to the G.91. The specification for the latter, AC 169b, differed only in calling for 180 n.m. radius and the carriage of a 1,0001b store. Neither called for air superiority or interception, and there was no requirement for supersonic dash.

The emergence of specific aircraft replacements was a move from the earlier idea of commonality, but reflected increasing British and Italian interest. A German/British brochure of December 1962 retained the basic 180 n.m./ 1,0001b load requirement, while the German/Italian requirement of May 1963 merely increased the weapon load to 1,2501b. The G.91 replacement galvanised into activity Focke-Wulf (as VFW was then), EWR and Fiat, and three designs were proposed to the German and Italian Governments between May and August 1963. They were the FW 1262, the EWR 420 and the Fiat G.95/4. For comparison purposes they were matched against the projected Hawker Siddeley P.1127 development, later to become the Kestrel.

Seven countries presented eleven projects whose analysis was entrusted to a project assessment commission, the report of which carried the designtion AC/169-D/26. NATO Basic Military Requirement 3 produced a profusion of paper designs. Derivatives of the Hawker P.1127 were the obvious British entry, and virtually all the power specified in the submissions would be provided by Bristol Siddeley or Rolls-Royce. Especially intriguing was the Republic/Fokker contender, planned around single Bristol Siddeley BS.100 lift/thrust engine. This impressive powerplant was to have a thrust in excess of 35,OOOlb, and its development is being partially financed througi the Mutual Weapons Development Program. The Republic/Fokker aircraft had variable geometry, and the thrust of the engine chosen released it from crippling weigh restrictions and may enable it to score on range.

Other entries were: the Dassault-Sud Balzac, essentially a Mirage III provided with four Rolls-Royce RB.162 lift engines between the intake ducts to the propulsion engine; the Messerschmitt/Heinkel Bolkow VJ-101, which had a quartet of RB.162s, each wing-tip and an engine of some 20,0001b thrust for propulsion, and the Fiat G.95, with two pairs of unspecified Rolls-Royce lift engines and two Bristol Siddeley propulsion turbojets.

Four were down-selected - the Dassault Mirage III-V, Fokker-Republic D.24 Alliance, BAC 584 and Hawker's P.1154, a P.1150 derivative with the BS.100 engine giving greater mission performance. Hawker submitted their proposal in January 1962. The evaluations showed that no project answered the NBMR-3 completely. However, two projects of very advanced design, Hawker P1154 (the United Kingdom) and Dassault Mirage III V (France) were retained, but the countries did not manage an agreement on the choice of one or the other formulae. The results of the competition were announced in May 1962 - the P.1154 won the technical competition while the Mirage III-V was viewed as better in terms of industrial work share; the two aircraft were joint winners.

The group submitted a report of its work at the Committee of Armaments in document AC/169-D/31 (revised), where it concluded there was no common program of development and production possible for the moment. The Committee took note on August 17, 1962 of it (AC/74-D/675) and transmitted to the Council (CM (62) 93), which asked to continue the study on the subject. The group re-examined the definition of the attack and reconnaissance plane, and work continued within commission AC/169 (LW) on light attack and reconnaissance V/STOL plane.

Great Britain, Germany and Italy agreed on joint development of a tactical nuclear bomber/reconnaissance plane. The basic specifications were derived from the Focke-Wulf FW-1262. The winning solution, the FW 1262 (submitted to the NATO Advisory Committee in March 1962), employed a single vectored thrust powerplant and two lift engines. The estimated performance and general characteristics of the Fw 1262 design had been used as the basis for the formal NBMR.3 AC 169b specification.

During the evaluation period between May 1963 and August of that year that the designation VAK 191 was given. The initials stand for Vertikal Startendes Augklarungs-und-Kampflugzeug (vertical take-off and landing fighter aircraft); the numbers indicate a successor to the Fiat G.91; and the final B shows that the project was the second of the four aircraft to be studied - the reference P.1127 Mk 2, for example, was the VAK 191A.

There were four proposals:

  1. VAK-191A - Harrier P.1170 mod
  2. VAK-191B - Focke Wulf FW-1262
  3. VAK-191C - EWR-340 (VJ-101D)
  4. VAK-191D - Fiat G.95-4

One notes two programs launched in 1963: the program of evaluation of the "Kestrel" (ex-Hawker P1127) by Germany, the United Kingdom and the United States following an agreement made in 1963; and the bilateral program of the VAK 191B launched following the German-Italian agreement to develop and build a light plane intended to replace the FIAT G.91. Great Britain withdrawn from this project in late 1963 when it became clear that the P.1170 would not be accepted, and it continued development independently.

Without a work program clearly defined, commission AC/169 (LW) was dissolved by the Committee of Armaments on June 29, 1966. Its old activities were transferred temporarily with advisory Group NATO for the air forces AC/22480 which, become group for l' armament of the air forces, confirmed its suppression with its first meeting in April 1967. Subsidiary group AC/169 and its organizations produced some 127 documents.



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