The RAN may be going forward with UAVs, but the hangar facilities on its new destroyers and pending frigates are going backward from those of the obsolescing Adelaide class. The design for the nine Hunter-class ASW frigates should be modified with the planned main and smaller UAV doorways on the stern end of the hangar replaced by two wide side-by-side doorways.
Press images suggest that the Hunter-class, which is derived from the British Type 26, has hangar arrangements tailored to satisfy the Royal Navy (RN), which routinely operates with one ASW helicopter per escort. Those arrangements are fundamentally inadequate for sub hunting and the wide area needs of the RAN where two ASW helicopters are more than twice as useful as one. The proposed hangar arrangements would similarly limit the manner in which a manned ASW helicopter could be operated in conjunction with a UAV large enough to be equipped with ASW sensors and weaponry.
The problem with the Type 26 design
The rear superstructure of the RN's Type 26 frigate includes separate hangar doorways for ASW helicopters and UAVs. One helicopter is stowed and maintained in a hangar on the centreline of the hull and is moved onto the flight deck via a doorway closed by a roll-up shutter. A smaller shuttered doorway to starboard, and possibly another small portside doorway, are provided for UAVs. Both shoulders of the whole beam superstructure are cut away to provide a short deck and a lightweight 30mm DP gun to port and starboard.
At the forward end of the main hangar, a centreline doorway is provided so that a second helicopter can be moved into a mid-ship mission bay. That bay is also intended for stowing up to four side-loaded rigid hull inflatable boats and other cargo. Storing a second helicopter in that bay would pre-empt much of its space, and moving the second helicopter - or a large UAV - back out for use could necessitate an awkward shuffling of both onto the flight deck and then transposing the stern-most back into the hangar.
Side-by-side doors are future proof
Embarking two ASW helicopters on a fleet combatant is standard practice in several navies. The Adelaide class frigates can hangar two SH-60 Seahawks side-by-side on a 139 metre hull with a maximum beam of 14 metres. Modern multi-role frigates are larger. The Italian version of the FREMM frigate has a double hangar with side-by-side doors designed to hold two SH-90 ASW helicopters or one SH-90 and one AW101 Merlin. That frigate has a hull length of 145 metres and a beam of 19.7 metres.
The SH-90 is the Italian ASW version of a medium size helicopter that is also in service with the RAN as the MRH-90 Taipan. It is not known which UAVs are embarked on the Italian frigate. But with the exception of helicopters converted for unmanned use, most in-service UAVs employed by NATO navies are small and readily moved, and probably stowed in hangar spaces shared with helicopters. Moreover, the flexibility provided by side-by-side doors would allow joint operation of an ASW helicopter with a large yet-to-be developed sensor and weapon-carrying UAV.
The RAN does not employ the AW101 Merlin but instead uses the MH-60R Seahawk, which is slightly smaller than the AW101. With its main rotor folded rearward and tail boom folded against the portside of its fuselage, the MH-60R occupies a cube 12.51 metres long by 3.35 metres wide and 3.94 metres high. The Hunter class has a hull length of 150 metres and a maximum beam of 20.8 metres. That beam is clearly adequate for a whole beam double hangar with two wide side-by-side doors and two medium-size ASW helicopters stowed one to port and one to starboard.
The Schiebel S-100 Camcopter occupies a cube about 3.3 metres long by 1.12 metres wide and 1.24 metres high. At that size a Hunter-class frigate could stow two or more UAVs on the hangar centreline for ready movement around a MH-60R and out through either of the side-by-side doorways. A more capable surveillance UAV with sonar/sonobuoy and weapons would be much larger, but no such purpose-designed UAV is yet in service with a NATO or affiliated navy. It is worth noting that the RAN reportedly intends to procure a UAV that will also be small enough to be operated from the Arafura class OPVs.
In short: to operate a mix of ASW helicopters and UAVs, the design of the Hunter class needs to be modified to have a double hangar with two doors. Each must be large enough for a MH-60R or similar helicopter (or a large UAV) and small UAVs stored on the centreline. The hangar arrangements and roof/hoist supports would need modification for stowage and movement of the helicopters and UAVs. Those modifications might preclude stowage of a helicopter or large UAV in the mid-ship mission bay, but that limitation might not apply to small UAVs. If either limitation did apply, it would enhance availability of the bay as a garage for RHIBs and containers/stores.
This is more than enough words to establish the basics; the hangar arrangements planned for the Hunter class are inadequate and need to be thoroughly revised.
Note: This article originally appeared as a comment on our website.