Julian Moxon/PARIS

AEROSPATIALE IS proposing to the French air force a new version of the ASMP air-launched nuclear missile, the ASMP Plus, which it says will have twice the range of the existing ASMP, and be half as expensive as the abandoned ASLP long-range stealth missile.

The French Government is considering the future of its nuclear-weapons launch policy, and sources indicate that the ground-based missiles in silos on Plateau d'Albion will be abandoned, leaving the submarine- and air-launched elements. The ASMP Plus is proposed as the least expensive solution to fulfilling the air-launched requirement.

The ASMP has been in service since the end of 1987, and will be nearing the end of its operational life in 2005, when the ASMP Plus would be ready for service entry. Aerospatiale had been working with British Aerospace on the ASLP until the UK cancelled its involvement as part of its decision to centre its nuclear deterrent on submarine-launched missiles. France then decided that it could not support alone the Fr10 billion (£2.56 billion) cost of development.

Modernising the ASMP would cost around Fr5 billion, the missile taking advantage of many of the ASLP's features, such as a new boosted-ramjet propulsion system, advanced inertial-navigation system and improved low observability. Aerospatiale has already carried out tests of the missile in an altitude chamber.

Range is increased to around 1,000km (540nm), by lengthening the missile to the maximum capability of the Dassault Mirage 2000N and Super Etendard launch platforms, allowing extra fuel to be carried for the ramjet. The extra burn time, and a more demanding flight trajectory, meant developing advanced thermal materials for the ramjet, which, one source says, is the "key" to the missile's improved capability.

The missile does not use the single-inlet (under the body) design of the ASLP, retaining instead the double-inlet (either side of the body) of the ASMP, but with revised shaping, to reduce observability. The design of the fins is also modified to lower the radar signature.

The ASMP Plus would cruise at Mach 2.5 after launch at low level, following a "lo-hi-lo-lo" trajectory instead of the "lo-hi-lo" trajectory flown by the ASMP. The missile would reduce height to near-ground level from cruise altitude several kilometres before arriving at the target, improving penetration and reducing the chance of detection.

Aerospatiale is pushing for full-scale development to begin within months. Sources indicate that the engine could also be used for the ANNG sea-skimming missile, which has yet to be approved for development.

Source: Flight International