PAUL LEWIS /WASHINGTON DC
Critical design review completion moves programme ahead - but ballistic protection and low observability issues remain
The Boeing Sikorsky RAH-66 Comanche programme has completed critical design review (CDR) of the overall weapon system, clearing the way for construction of major assemblies to begin in August. Ballistic protection and low observability issues, however, remain outstanding.
US Army RAH-66 programme manager Col Bob Birmingham says the helicopter met 73 of 86 component and system level CDRs and while there were several chits or discrepancies it is hoped to have these addressed by September. The CDR is the last milestone before assembling the first of five development machines, the first of which is due to fly in mid-2005.
The CDR covers the initial four limited user test and training helicopters due to be delivered in late 2006. Under the programme's spiral development plan, separate CDRs will follow for Blocks 1, 2 and 3, beginning next year with the initial operational version due for delivery in 2009.
Among issues to be resolved is a study of the armour required to protect the helicopter and two-man crew. Boeing Sikorsky's design makes assumptions on the level of ballistic robustness, but updated modelling with shots from different angles "found it did not perform as well as we would like. We're going back to looking at the model and the requirements we've designed," says Birmingham.
The army's revised modelling assesses the threat from a particular type of round, but Boeing Sikorsky and the army decline to give details. Conflicts since the mid-1990s have highlighted helicopters' vulnerability at close range to rocket propelled grenades.
Armour has a direct bearing on weight, which the programme is fighting to reduce for the Block 3 version to have sufficient growth margin over and above its key performance parameters. As a result, the programme office has asked the army's Aviation Applied Technology Directorate to look at developing lighter weight armour.
Chuck Allen, Boeing Sikorsky RAH-66 programme director, says most of the remaining outstanding issues are "process" rather than "product based". The only other "chit of any significance" is the location of the radar warning receiver, which affects radar cross section. Infrared signature is listed by the army as an issue, but Birmingham adds: "Its a minor design replan. We know what we have to do differently, we just need to do it."
Source: Flight International