RAST vs Decklock

[solidRolf]

Hi, I'm new to the forum.

I am looking into the advantages/disadvantages of the Convetional 'harpoon' decklock system that I know is used by the RN over the Recovery Assist, Secure and Traverse (RAST) system pioneered by the Canadians.

The RAST or 'beartrap' system seems to be the best in my view at the moment by the fact that it guides the helicopter to be secured to the arresting beams and the wire tension allows the helicopter to be moved in phase with the ships pitch and gradually brought down as the wire provides a guiding and centering effect.

If this is the case why do navies still use the conventional deck lock system?

I do not much knowledge on this systems and it would be great if any of you could explain the benefits of each.

[Um... lifting...]

If this is the case why do navies still use the conventional deck lock system?

Cost. Complexity. Crewing. Capacity.

Deck lock (known variously as Harpoon, Talon, and probably other things) consists of no moving parts on the ship. The maintenance for the ship consists of periodic cleaning and inspection of the grid and fasteners. The helicopter's system has electrical, mechanical, and hydraulic bits to it.

Beartrap (RAST) consists of lots of moving parts, requires active crewing and training on the part of the ship and maintenance of both the helicopter's and ship's parts of the system.

RAST can handle rather a lot of weight and also traverses the helicopter into the hangar. Deck lock has a lower weight limit and has no traversing function.

Deck lock can't induce inflight oscillations, RAST can. Helicopters using RAST have rolled over. A pilot can land and use deck lock unassisted. Not the case with RAST. I've used one but not the other.

[peterperfect]

Once trapped in the RAST the aircraft stays attached to the ship via its belly probe, can be traversed in and out of the hangar and is never detached until 5 seconds before the next launch, even days later without the need to ever become a liability in rough weather. Provides more options. pp

[Shawn Coyle]

Deck lock requires the pilot to be able to maneuver the helicopter accurately over the grid - pilot training and helicopter agility become issues. Lynx can do the rapid maneuvering, Sea King can't dance quite that quickly.
Deck lock won't let you automatically take helicopter from hangar to deck position (and vice versa) - how can you man-handle a Sea King in rough weather?
Both have advantages and disadvantages.

[Praet]

how can you man-handle a Sea King in rough weather?

With difficulty - however, you don't have to. There are handling systems available that can do that for you.

[dangermouse]

Merlin has Decklock

It's bigger than a Sea King, but has much more control authority so can be accurately positioned, the RN uses a deck lock on theirs coupled with a separate deck handling system (PRISM) on frigates that can move the aircraft in/out of the hangar without external assistance. When over the grid the decklock is egnaged the deck handling system is stowed and the aircraft can then start and takeoff as normal

DM

[solidRolf]

Many thanks for the replys, just what I was after!