GKN Westland has proposed an upgrade of the EH101 Merlin helicopter to carry higher weight, as part of a growth plan partly devised to meet the UK requirement for a Future Amphibious Support Helicopter (FASH) replacement for the Royal Navy Commando force's Sea King HC4. The FASH requirement is likely to be contested by the Merlin, the Bell-Boeing V-22 Osprey and the Sikorsky S-92.
The upgrade is mainly to allow for future weight growth in the Merlin Mk2 naval variant, which has a maximum take-off weight of 13,530kg (29,800lb), but it will also make the Merlin compliant with the FASH requirement. The improved-performance Merlin has been included in a response to a request for information from the UK Ministry of Defence for the FASH, which has an intended in-service date of 2008. An invitation to tender is likely around 2001.
Part of the requirement is the ability to carry the Royal Marines' future lightweight mobile artillery weapon system, which has a projected weight of around 5t. The FASH requirement is for the weapon to be carried 80km (45nm), and for the aircraft to return to base unladen. The Merlin can lift this weight as an underslung load, but only with reduced fuel and therefore shorter range.
Westland plans to improve the Merlin's performance by using the upgraded 1,735kW (2,330shp) RTM322-04 engine intended for the NH90, improved-performance BERP 4 rotor blades and by increasing rotor RPM to 105% of the current limit, giving the Merlin a maximum all-up weight of 16t.
The shape of the FASH could be decided with the invitation to tender in 2002, but many factors remain unresolved, particularly given the emerging requirements of the UK Joint Helicopter Force.
Source: Flight International
