THE VAUTOUR PAGES

SNCASO / SUD AVIATION SO.4050

HISTORY

Introduction:

1) Soon after the end of WWII the French military industry needed urgent rehabilitation. The aviation industry had to respond to the new Air Force's requests for a whole range of modern aircraft, comparable with the Western AFs service that time.

2) Aid of the U.S and the U.K supplied interim solutions - American aircraft (built or assembled in Europe), and British (assembled and upgraded by French manufactories). Thus The FR-AF was equipped, during the late forties' and the early fifties' by foreign combat aircraft.

3) The French aviation industry achieved rapidly extraordinary abilities, in design. development and production. A series of original prototypes were built and flown, but the majority of these projects remained experimental. Nevertheless these contributed much knowledge for the future successful products.

4) The first mass production jet fighters were of Marcel Dassault design, the Ouragan and the Mystere-4. It is to say that these first fighters were actually the equivalents of American jets which had been developed and combat-proven several years earlier (The Ouragan was comparable with the F-80, F-84 and the naval F9F-2, and the Mystere-4 to the F-86, all of these already participated in the Korean War (1950-1953).

5) The main weakness of the French aviation industry was the power of the engines. The first turbojet engines were French-built British motors (as the Rols-Royce Nene) or their "extrapolation" (as the H.S. Verdon). The original French engines of the time (as the Atar 101 series) were significantly inferior to the British engines, already operational ( as the R.R Avon series and the A.S. Sapphire ), which had stronger thrust, less weight and lower specific fuel consumption.

6) The French manufacturers were either governmental (as SNCASO & SNCASE) or privately owned (as Dassault, Breguet and others). Both types of companies had excellent professional teams, but the management of the governmental firms tended to be less efficient and "excelled" in troublesome bureaucracy. These characteristics had a significant influence on the Vautour's development and production.


Early Designs - SO-M1, SO-M2 and S.O. 4000 Vautour I

1) One of the most interesting projects was the S.O. 4000, an advanced all-metal aircraft, designed in response to a requirement for a tactical bomber.

2) SNCASO began the development via two half-scale models: the first was the SO.M1 glider, designed to explore aerodynamics, the second, SO.M2 was an engined pre-model.

3) The SO.M1 was launched from rails built above the fuselage of the SE.161 Languedoc transport. There is no evidence it was ever launched ( one source claims that its first flight was performed in September 1949 ??).


4) The SO.M2 flew first in April 13, 1949, powered by a single R.R. Derwent turbojet, of 3,500 lb. thrust, (the Meteor's engine). One example built.

See : [ S.0. M1 & M2 Drawings ] and ___ [ S.0. M1 on the Languedoc ] (not linked) .

5)The S.O M2 specifications

  • Experimental, "half-sized" S.O. 4000 planned prototype.
  • Structure: Metal, swept wings, in 'unhedral' position.
  • Crew: pilot.
  • Dimensions - length: 9.99 m. , span: 9.08 m. wings' area: 18.0 sqm.
  • Weights - empty: 3,840 kgs. , gross: 4,700 kgs.
  • Max. speed envisaged: 1,000 kmh.

6) Those two models supplied data for the development of the S.O.4000, with several new features. The S.O.4000 prototype, named Vautour, was a two-seat, two-engine aircraft, that made its sole flight in March 15, 1951. Just one unit was built. It was abandoned in favour of the Vautour II.

7) S.O.4000 "Vautour I" Specifications:
  • All-metal construction.
  • Crew - 2, sitting in tandem.
  • Engines: 2 x 4,982 lbs. Hispano-Suiza (Rolls-Royce) Nene Mk.102, located at the rear fuselage, lateral inlets between the cockpit and the wing roots, and exhausted via plain nozzles inboard of the tailplane halves.
  • Dimensions: length - 19.75 m., span - 17.86 m. wings' area - 75.0 sqm.
  • Weight: 16,850 kgs. (empty), 22,000 kg. (planned, max. loaded).
  • Max. speed - {unknown if attained): 850 kmh at 9,000 m (29,530')
  • Armament (planned) : 2 x 20mm guns in wing tips pods plus
    * Up to 1,800 kg. in a lower-fuselage weapon bay (4 x 450 kg. bombs) and
    * External loads: 1,800 kg. (four 450 kg. bombs).
    * Max. bombs load: 3,600 kg,
  • "Shoulder-set" wings, quarter-chord sweep of 31 degrees.
  • Tail: modestly swept flying surfaces; mid-set tailplane.
  • Retractable landing gear: a single-wheel nose unit, four main units arranged in two tandem pairs.
8) The S.O.4000 had already some features of the future Vautour, but was seriously underpowered and unstable.


S.O. 4000 [ courtesy of "Dan" ] _ [ SO-4000 full size ] .



S.O. 4050 Vautour II Project

1) In July 1951, the FR-AF issued a requirement for an advanced warplane capable of undertaking the all-weather interceptor, tactical attack and high/low-level bomber roles.

2) SNCASO decided that drastic redesign could transform the S.O.4000 into a model that could satisfy this requirenent. The result was the S.O.4050 Vautour II project. The team that designed the Vautour was headed by the engineers Jean Parrot and Jean Weil.

3) The two obvious changes were the new type of landing gear, (bycicle arrangement with two twin-wheel units under the fuselage, and two single-wheel units for stability), the installation of the engines (under the wings, at about one-third chord), and changes in the tail surfaces.

4) The S.O.4050 design was considered very successful, and 3 prototypes , according to the 3 roles required, were ordered. The sub-types, which possessed 90% commonality, were designataed: A - tactical attack, B - bomber, N - ( nuit- night) all-weather interceptor.

Prototypes



[left: as built ; right: modified ] [ iaf-mag 45/1957 ]

1. The three prototypes were built in a quite short time, and were tested with several different engines. At first these were numbered 01, 02, 03 but as the pre-production were built, the numbers changed to 001, 002 and 003.

    001 ("quasi" N, two-seater)
  • It was built as two-seater for testing reasons. It was not an actual "N" prototype.
  • Civil registration: F-ZWRU
  • This prototype flew first in October 16, 1952, piloted by Jacqes Guignard, chief test pilot of SNCASO, at Meulan-Villaroche air field.
  • It was iniatally powered bt two ATAR 101B series engines, of 5,280 (5,577?) lbs. of thrust, each.
  • After the first flight it stayed for two months, awaiting the analysis of some 200 parameters defined for the exPerimental flight. Its second flight tok place only in January 19, 1953.
  • In May 1953 it was equipped with the 6,175 lbs. Atar 101C.1 (101D ?) engines.
  • Flight tests led to the addition of a ventral fin, under the tailplane. This became standard for all later Vautours.
  • In June 30, 1953, its 30th flight, the Vautour-001 became the first two-engined, two-seater aircraft to exceed the speed of sound (in a shallow dive), in Europe. The dive began at 43,000 feet and the typical "double bang" was clearly heard.
  • With the same configuration it was revealed to the public, in flight, at the 1953 Paris airshow ("The Aerial Salon", 4&5 of July). The "001" demonstrated a climb of 34 degrees to 43,000 feet, and in descending broke another time the speed of sound barrier.
  • Further tests in CEV included varied profiles of flight, and were aimed for aerodynamical studies. During these flights the "001" reached an altitude of 45,000' and a level speed of 0.96 Mach was recorded. In dives the prototype exceeded Mach 1.03.
  • Its 100th flight took place in December 2, 1953, and the 100 hours of flight were done in March 10, 1954.
  • During tests it was modified with a dorsal fairing connecting the rear of the cockpit with the leading edge of the vertical tail surface. (This became standard on all later Vautours). It also got a pointed nose housing the CSF radar. (* see pictures at top of this paragraph).
  • The "001" prototype was exhibited to NATO experts, and a very senior American delegation evaluated the aircraft, being very much impressed. The Belgian, looking for the Meteor-11 replacement, flew the "001" and performed interception trials, with the early radar, versus the Night-Meteor. {Later the "09" was shown to the Belgian, but their preference was finally the Canadian CF-100 Mk. 5}.
  • The next stage involved the installation of a CSF radar and an aerial, that added 200 kgs. in the nose. The radar (replaced by the Drac-32AI), needed fitting of a "pointed" new, nose. The radar was tested against "adversaries" - light planes, the Ouragan and the Meteor-11.
  • Then was the turn of the guns, several variations were fitted (2 x 37 mm. , 2,3 & 4 x 30 mm.). At the end of 1954 tests show the destructive influence of the guns' fire on the radome. Firing trials continued in Cazaux, 1955, and included deliberate flights without the radome covering.
  • The first nocturnal flight was carried out in October 14, 1954, reaching 44,000'.
  • During farther flights Mach 1.045 was recorded.
  • The "001" suffered a harsh emergency landing, December 12, 1954. The aircraft spent some 4 months in repairs, and two ATAR 101E.3 (to become the standard engine of most production-Vautours), of 7,716 lbs. each, were installed.
  • The aircraft didn't last for long after. In May 16, 1956, at high altitude, it went into a "flat spin" , and, after an uncontralable dive, the crew ejected at 10,000', and rescued. This was the end of "001", after more than three and a half years, and over 300 flight hours.


    002 (A, single-seater)
  • Civil registration: F-ZWSI
  • Roll out: November 28, 1953
  • First flight: December 16, 1953
  • Powerplant: two 6,173 lbs. Atar 101C, later replaced by the 6,217 lbs. 101D.
  • During later tests it was powered with several more engine types (of 6,620 to 10,000 lbs.thrust), including, in 1955, two R.R Avon sub-types, of 9,260 and 10,000 lbs.
  • This prototype was the first to test gun firing.
  • In 1957 it began testing air-refuelling equipment.
    003 (B, two-seater)
  • This variant had a separate glazed nose for the bomber-navigator, and an "all flying" (Monoblock) tail.
  • First flight: December 5, 1954
  • Powerplant: two 8,000 (or 8,157 lbs.) Armstrong-Siddeley Sapphire-6 turbojets.
2. As soon as mid. 1953, even before the 3rd prototype went to air, six pre-production machines were ordered: 1 B, 2 A and 3 N.

Pre-Production Series

1. The 6 pre-production Vautours were flown during 1955 and the beginning of 1956. These also had a variety of engines installed.

2. The pre-series aircraft were numbered 04 ( B ), 05,07 ( A ), 06,08,09 ( N ).

    04 (B)
  • Completed: December 4, 1954.
  • First flight: March 18, 1955
  • Powerplant: Atar 101 (?).
  • d) The aircraft was handed over to the FR-AF, for trials, on March 25, 1955.
    05 (A)
  • First flight: June 14, 1955.
  • Powered by the 9,500 lbs. R.R. Avon R.A.14 engines.
    06 (N)
  • First flight: June 17, 1956.
    07 (A)
  • First flight: February 11, 1956.
  • Powerplant: British turbojets, R.R. Avon or A.S. Sapphire.
    08 (N)
  • Completed: December 10, 1955.
  • First flight: March 1st, 1956.
  • Powerplant: two 8,157 lbs. Sapphire-6 turbojets.
  • Tested several more engines. (Atar-8 included ?).
    09 (N)
  • This aircraft flew first October 18, 1955, powered by two R.R Avon RA.8 (later - RA.14), of 10,000 lbs. thrust.
  • Due to the powerful engines it achieved extraordinary performance, (half the time to 12,000 m. as compared to the Atar-101 powered aircraft, 3.5 min. vs. 7 min., respectively).
  • Unfotunately this aircraft was lost during tests of launching the internal-housed 68mm rockets, its crew killed (1957 or 1958).
3. It is possible that one of the aircraft (08 ?) was powered with the 9,700 lbs. Atar-8 turbojets.

4. The various trials were carried out at several FR-AF test centers, mainly Bretigny (aeronautics), Cazaux (armament) and Mont-de-Marsan (piloting).

5. The initial expectations were as high as to forecast some 600 aircraft to be built, about half of the tactical strike/attack variant, some 200 all-weather fighters and ca. 100 bombers.



5. The Vautours' Characteristics:

The Vautour was a unique design, embodying features no other two-seat, two-engined aircraft had. The three-mission design, the special undercarriage, the long range and the powerful armamrnt, all these were advantageous features. On the other hand, the Vautour had some weaknesses, mainly by being underpowered, deserving stronger engines that could extract more of the aircraft potential.

See the Specifications chapter for full details.


The Vautours' Contemporaries

The Vautour's contemporaries that were already in service in 1957, or entered service during 1956-1957, according to categories ( attack/light bombers and all-weather fighters), were:

A. Strike / Attack / light bombers - (two engined, two/multi seaters)

  • The British, English Electeric Canberra B.I.8 & B.2
  • The American modification of the Canberra - Martin B-57.
  • The Soviet Ilyushin IL-28.
  • The American, carrier-borne, A-3A/B Skywarrior
  • The U.S.A.F modified version of the A-3: B-66 Destroyer.
  • The British, carrier-borne, long range strike aircraft, Buccaneer S.1

    B. All-Weather Interceptors (two-engined, two-seaters)
  • The Avro-Canada CF-100
  • The Soviet Yakovlev Yak-25/Yak 27
  • The British, carrier-borne, Sea Vixen
  • The British Gloster Javelin

    See [ Vautour's Contemporaries ] chapter. page



    Orders and Production

    1. At the end of 1955 the FR-AF issued its initial order for 480 Vautours: 300 IIA, 40 IIB and 140 IIN.

    2. The Vautours were planned to replace a series of elderly types, during the next years:
    a) The IIB bomber was to replace the prop-engined A-26 Invader, and to become the main long-range bomber with nuclear and conventional capabilities.
    b) The IIA tactical attack variant would replace all the fighter- bombers in service (as several prop-engined types and the jet-powered Mistral and Ouragan) and to be armed with a variety of bombs, rockets and ASMs.
    c) The IIN variant was to enhance the all-weather capability of the FR-AF, and should replace the Meteors N.F.11 (The single-engined, single seater F-86K Sabre was to be replaced in a later stage). This variant was planned with a heavy air-to-air armament: guns, rockets and missiles.
    3. Unfortunately, budget limitations besides political factors intervened and caused a drastic cut off in the Vautours orders.
    a) Budget constrains cut off the initial order to 360 aircraft, (220 A? 100 N? B-40), with a declared tendency to lessen this quantity once more.
    c) Internal competition among the French leading manufacturers, aroused a discussion about the right place to invest, either in the proven products (as of Dassault, then developing the Super Mystere and designing the Mirage), or to risk a purchase of a not proven aircraft in such a large quantity.
    d) The internal debate was "solved" by the U.S.A. There is more than a suspicion that the Americans, who concentrated in building heavy bombers and fast fighters, were not interested in the success of a European multi-purpose aircraft which could endanger their control over the western export market.
    c) the U.S offered France an immediate delivery of 200 F-84F (150 fighter-bombers and 50 RF-84F), for "dump" prices. This, bargain of oppurtunity, was quicly accepted. (Later the U.S. provided the French with the attack version of the Super Sabre, F-100 (88 -D and 12 -F, by this cancelled the need for a French strike variant).

    F-84F Thunderstreak
    150 F-84F & 50 RF-84F were sold to France, by that the U.S. prevented mass production of the Vautour IIA
    [ preserved aircraft at the FR-AF museum ]

    4. Orders for the Vautour went down to 160, and finally to 140 Aircraft, including 30 A, 40 B and 70 N.

    5. First production aircraft flew first as follows:
    Vautour IIA No. 01 - April 30, 1956.
    Vautour IIN No. 301 - October 10, 1956
    Vautour IIB No. 601 - July 27, 1957.

    6. While the final order was decided the serial production of the IIA had already commenced. At the time the first production aircraft (IIA) went out of the line, Israel made its order for 28 Vautours, including 17 IIA. The Vautours IIA to Israel were delivered beginning July 1957.

    7. The Vautours, prototypes and production aircraft, were assembled in SNCASO factory at Saint Nazaire.

    8. All the Vautours IIA (30) were completed till February 1958. The IIN and IIB manufacture continued till 1959 and 1960, respectively

    * Remark: on March 1st, 1957, SNCASO merged with SNCASE to form the Sud Aviation company. Products of the former had been designated as SO- , and the latter SE- . Despite the change in the manufacturer the designation SO-4050 was kept.


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    First Flights - Prototypes, Pre-production and Production Aircraft
    Date Aircraft Remarks
    April 1949 S.O. M2 Engines: 2 x R.R. Derwent ; sole flight
    September 1949 S.O. M1 glider Launched from a Languedoc (?)
    March 15, 1951 S.O. 4000 Vautour I Engines: 2 x R.R. Nene 102 ; sole flight
    October 16, 1952 Prototype "N" 01 (later 001) Engines: 2 x Atar-101 B.2
    December 16, 1953 Prototype A 02 (later 002) Engines: 2 x Atar-101 C
    December 5, 1954 Prototype B 03 (later 003) Engines: 2 x Atar-101 D.2; ASS Sapphire-6
    March 17, 1955 Pre-production B 04 2 x Atar-101 D.2 ; Delivered to the FR-AF
    June 14, 1955 Pre-production A 05 2 x Atar-101 D.2
    June 17, 1955 Pre-production N 06 2 x Atar-101 D.3
    October 18, 1955 Pre-production N 09 2 x R.R. Avon 14
    February 11, 1956 Pre-production A 07 2 x Atar-101 D.3
    March 1, 1956 Pre-production N 08 2 x Atar-101 E.3
    April 30, 1956 First production A s/n 1 2 x Atar-101 E.5 ; Delivered to CEV
    June 12, 1956 Second production A s/n 2 2 x Atar-101 D.3 ; Delivered to Wing 30
    October 10, 1956 First production N s/n 301 2 x Atar-101 D.3 ; Delivered to CEV
    November 28, 1956 Second production N s/n 302 2 x Atar-101 D.3 ; Delivered to CEAM
    July 31, 1957 First production B s/n 601 2 x Atar-101 E.3 ; Delivered to Melun
    February 24, 1958 Last production A s/n 30 2 x Atar-101 E.3 ; Delivered to CIB
    July 31, 1959 Last production B s/n 640 2 x Atar-101 E.3 ; Delivered to EAA
    July 18, 1960 Last production N s/n 370 2 x Atar-101 E.5 ; Delivered to EAA
    Production Period : [ 140 aircraft ] April 1956 - July 1960 ; ca. 50 months ; avg. 2.8 a/c per m.


    [ A full list of the 140 production Vautours is under construction ]



    Export

    The only country the Vautour were exported to, was Israel.

    Only one other country, Belgium, evinced interest in the Vautour (N). In 1955 The Belgian AF planned to replace the Meteors N.F.11.
    The Belgian's priority was for a long range, two-seater all-weather fighter, with modern search & fire control systems and heavy armament.
    The altrnatives of the time (the two-engined CF-100, Javelin F.A.W.7 and the Vautour IIN, and also the single-engined F-89K Sabre and the two-seater SAAB J-32B Lansen) were considered.
    The preferred fighter was, eventually, the Avro Canada CF-100, due to its better fire-control system (American MG-2, built in Canada), rather than those of the Vautour or the Javelin, (the two other main candidates).
    In 1957 Canada transferred to Belgium 53 CF-100 Mk.5, all- rocket armed (and with AAM capability), to equip two squadrons.



    Service

    1) The Vautours served for a long time with the FR-AF and with the IAF.

    2) The FR-AF IIN variant entered service mid-1958 and was replaced by the Mirage F.1C/B by end of 1973 and during 1974.

    3) The FR-AF IIB entered service towards the end of 1958 and was retired from operational service end of 1978 and during 1979, replaced by the Mirage F.1C.

    4) Some Vautours continued in testing missions well into the 80's.

    5) The few French Vautour A (13) served for training and tests. Two of these were delivered to Israel in 1967 and 1968.


    6) The majority of the Israeli Vautours entered service during 1958, and served till 1970. They gradually phased out till March 1972. The Vautours were replaced in their respective roles by the F-4E and RF-4E Phantom.

    7) The IAF Vautours participated with excellency in the Six Days War, 1967, and ended their life as decoys in the Sinai desert. Reports about "ten Vautours... in the 1973 war" are without basis.




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