S-4 and S-45 IRBM projects (France, Cold War)

[Grey Havoc]

S-4 - France Nuclear Forces

The S-4 was an intermediate range, silo-based and mobile, solid propellant, MRV capable ballistic missile. The S-4/S-45 program was cancelled in 1991. In 1987 the French Defence Ministry announced a 10 year development programme for the land-based S-4 IRBM to replace the S-3 missile in the late 1990s. However, doubts were expressed in 1988 and several options were explored including land basing a variant of the submarine-launched ballistic missile M-4, land basing a variant of the M-5, or an improved S-4 design known as S-45. In 1991 it was decided to cancel the S-4/S-45 program and to develop a land-based variant of the M-5 SLBM to replace the existing S-3 missiles [an effort which was also cancelled].
The S-4 was a two stage, solid propellant, land mobile or silo-based system, with a range of 3500 km. There was planned to be a MIRV payload of three TN-35 warheads, perhaps with yields in the 20 kT range. The original S-4 program called for 36 missiles capable of random dispersal around France by air or road in times of tension. Some reports suggested that there would be 18 missiles for the land mobile force, and the other 18 would replace the S-3 fixed-based force on the Plateau d'Albion.

https://calhoun.nps.edu/bitstream/handle/10945/26902/britishfrenchstr00bate.pdf?sequence=1&isAllowed=y

The RPR-UDF government in office from March 1986 to May 1988 originally proposed building 30 single-warhead mobile IRBMs now designated S-4 to replace the 18 fixed S-3 IRBMs and the Mirage IV-P bombers by 1996 [Ref. 24: p. 176].The military program law for 1987-1991 described S-4 as "alight ballistic missile capable of depressed trajectories and equipped with a penetration capability permitting it to reach defended targets." [Ref. 29: p. 5649] Some have likened the S-4 to the U.S. Midgetman missile [Ref. 30: p.40]. Jane's Weapon Systems 1988-89 described the planning for the S-4 as a two-stage, solid-propellant , land-mobile system with a range of 4,500 kilometers, each missile carrying three targetable and possibly MIRVed warheads in the 20 kiloton range capable of random dispersal around France by air or road in a period of tension [Ref. 7: p. 4]. Basing modes for the S-4 have yet to be determined,however. In September 1988 the French Defense Minister Jean-Pierre Chevenement, in presenting the military budget program for 1989 indicated that the S-4 project would undergo a significant delay due to cost overruns in the new generation nuclear submarine program [Ref. 31: p. 35]. The S-4 program was placed on hold in 1988 and is still in an uncertain status. The program technicians have been directed to maintain a certain technological know-how without proceeding to a development stage [Ref. 32: p. 143. Some military officials have expressed an interest in seeing the S-45, a land version of the M-45 submarine missile, placed in the silos .rather than to have them abandoned completely [Ref. 33: p. 9]. Ultimately several questions remain unanswered by the French government at this time. Should the missile force on the Plateau d'Albion be modernized at all, and how? Should a dedicated land-based triple-warhead missile (S-4)be developed? If it is developed, how should it be deployed? At any rate, as stated before, the French government under President François Mitterrand continues to place priority on submarine strategic nuclear modernization at the expense of land-based force improvements.

 

[PMN1]

Wonder what the vehicle for the land based mobile missile looked like?

 

[TheKutKu]

SX also kknown as S4/S45
Pre-studies were started under Giscard in the late 70s as a "French Pershing II",
DU MISSILE BALISTIQUE AU LANCEUR... by Serge PETIT
Académie de l’air et de l’espace ANNALES 2015

During this time, under the authority of François Calaque, preliminary studies began on the successor to the SSBS S3 called SX (small 10/11t missile), where different types of deployment were evaluated, as the silos became more vulnerable to increasingly precise first strikes. Two possible solutions: harden a fixed system or make it mobile to avoid being vulnerable to a first strike. In 1983, I took responsibility for phase A/B of the development of the new SX strategic missile; among the different modes of deployment, the mobile system seemed to be the most effective, a 38-ton semi-trailer vehicle that was stationed on air bases and deployed in times of crisis, the missile was tri-loaded. Too much erroneous and caricatural information
circulated about this type of deployment, which was studied closely with the Air Force.
Then this program will follow the French political alternations political changes in France, with periods of slowing slowing down and accelerating.

In 1984, the programme was slowed down; I then took over the management of the entire programme for this new weapon system, and we continued to study both the missile and the deployment of this weapon system with the various operational constraints, such as transmissions, protection and, of course, security... Work with the DGA, but also the Air Force.
In 1986 (cohabitation) the program was launched and took the name S4; the missile became a single-charge missile and was deployed on a VTL 1, a true autonomous semi-trailer, but also in a second phase, in silo. To better understand these decisions, it is necessary to compare the international political events of the time, and in particular the East-West balance on antiballistic defences with the SALT agreements.
On the industrial side, development of the first and second stage boosters (701 and 702) and the biliquid propulsion system (SYBIL) was launched (the upper stage, the model of which is still on display in the Snecma museum in Villaroche). In November 1987, the first 15-month tranche of the development contract was signed for 1 billion francs. In 1988, political changeover and, at the end of the year, a new delay, it takes six months to review the budgets and governmental defense priorities.

The mobile system and the VTL (Véhicule de transport et de lancement) were stopped - a prototype vehicle had been developed and had begun its trials with the Air Force - deployment would only be in silos; the Albion plateau had to be reviewed and modernized, in particular to make it invulnerable to a non-nuclear attack, which was not a matter of course.
I was then entrusted with all the SSBS programs, development of the S4 and maintenance of the S3 weapon system. It should be remembered that Aerospatiale was the industrial prime contractor for the entire program, and as such had a very important role to play with the DGA and the French Air Force in maintaining the entire system in operational condition:
PCT2 Transmissions, ZL3 , missile etc. Two teams, one at Mureaux and the other at Apt on the St-Christol air base, ensured all the activities of the force's operational maintenance on behalf of the DGA and the Air Force.
In 1989, the S4 became the S45 by integrating penetration aids of the M45 class, which is currently being developed, with a new high part and thus a very superior penetration of adversary defences. The development of the S45 missile continued with the first bench firing of the 701 (1990) and 702 (1989) propellants of the two powder stages, as well as the SYBIL engines. In 1990, the programme was again spread out with reduced funding, and in December a Defence Council was held to decide on the continuation of the programme

But for us, industrialists, on July 12, 1991, we receive the notification of the DEn of the cancellation of the contract and thus, the stop of the program. My deputy Gérard Bréard will take charge of it.
With the benefit of hindsight, this was probably the right decision - 1989 was the fall of the Berlin Wall. For the manufacturer, of course, it's a different matter, with teams to be reassigned and loads lost, but overall, it won't pose an insurmountable problem.

I should take a look when I go at the safran museum...

 

[flateric]

photos (c) Muxel

 

[TheKutKu]

photos (c) Muxel

Thanks! I had meant to go there last saturday but I had a hitch...

 

[TheKutKu]

"La Maitrise du Feu; 40 ans de propulsion solide et composite" by Felix Torres, ,gives the following characteristics for the two booster stages 701 and 702:

701
Diameter: 1.35m
Length: 3.5m
Gross Mass: 6,600 kg
Propellant Mass: 6,100 kg
Propellant type: Butalane
Combustion Pressure: 100 bar
Burn time: 60s
-Carbon-Resin epoxy wound structure
-Flex-seal bearing nozzle
-Carbon-Carbon joint
-Phenolic carbon divergent nozzle
Designed in 1988
First ground test fire: July 12th 1989
Cancelled in Jully 1989

702
Diameter: 1.2m
Length: 2.4m
Gross Mass: 2,500 kg
Propellant Mass: 2,300 kg
Propellant type: Butalane
Combustion pressure: 85 bar
Burn time: 42s
-Carbon-Resin epoxy wound structure
-Flex-seal bearing nozzle
-Carbon-Carbon joint
-Phenolic carbon divergent nozzle
Designed in 1988
First ground test fire: June 15, 1989
Cancelled in July 1991

Some additional comments:

"The ground test happened only 2 years after the start of the program"
"The 702 has two characteristics for its time, the first being ground fire tested: A very light nozzle, making up less than 1.5% of the total mass of the booster, and with a thrust vectoring angle twice higher thanthe M4's, it has a flex-seal bearing nozzle with a composite frame for thrust vectoring and a SEPCARB vein piece (?) significantly simplifying the architecture"
"The structural parts that used to be protected by thermal insulationare replaced by unique thermostructural parts that do both roles;one of the benefits of SEPCARB carbon-carbon and their great very-high temperature mechanical properties; the use of these materials enable a halving of of the mass of the bottom part of the booster compared to the M4 generation, proof of the advantages of the "all-composite""

 

[TheKutKu]

S45 Third Stage SYBIL 's engine on its test stand in SEP (now Safran Aircraft Engines) Villaroche.