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Offline Harrier

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Australian Invincible
« on: November 07, 2014, 06:56:50 am »
Image of the Vickers proposal for a modified Invincible Class ship to replace HMAS Melbourne. The enlarged hangar and removal of Sea Dart are of note. Also Invincible image for comparison.


Found at:
http://warships1discussionboards.yuku.com/topic/24222
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Offline pathology_doc

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Re: Australian Invincible
« Reply #1 on: November 07, 2014, 08:04:12 am »
Given that us Australians had actually been involved in talks regarding buying the ship, was this a proposal for a Melbourne replacement or a proposal for what was actually going to happen to Invincible as part of the sale? What was driving the proposal? i.e. did the RAN not want the Sea Dart GWS with all its added parts and servicing complexities, given that they were already operating the US Tartar/Standard in their bigger destroyers? Certainly there was Australian technical experience with the system, which AFAIK had been test-fired at Woomera, but whether this would have translated to a desire for service introduction when it was the only such system in the RAN is another matter.


Replacing Sea Dart with Tartar/Standard would have been an expensive proposition, even if the hull volume issue had allowed a lift-out-and-replace solution for the launcher. If you don't want to operate two such completely different systems in such low numbers, better to ditch the SAM launcher in the carrier and put the volume to use.



IIRC all three through-deck cruisers did lose their Sea Dart systems in favour of an expanded air group eventually (Why? Retirement of Sea Dart in destroyers ---> lack of support/spares? Or just a desire for a bigger air group?). How does this proposal compare in detail to what they actually went through with, and to what degree might it have inspired the conversion that actually happened?

Offline JohnR

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Re: Australian Invincible
« Reply #2 on: November 07, 2014, 08:58:39 am »
I believe this must be an earlier proposal for the replacement of Melbourne designed to meet the RAN's requirements.  The sale of Invincible was a last minute bargain basement offer after Nott's decision to reduce to RN carrier force to 2. 
 
Apart from the extension of the flight deck over the forward mooring deck, the reshaping of the hanger from the 'as built' dumbbell shape would seem to indicate that the air intakes from the port side were deleted, suggesting an alternative power plant.
 
The deletion of the Sea Dart installation was done to enhance the aviation facilities, not as far as I am aware due to any shortage in spares.
 
Regards

Offline pathology_doc

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Re: Australian Invincible
« Reply #3 on: November 07, 2014, 10:03:59 am »
The deletion of the Sea Dart installation was done to enhance the aviation facilities, not as far as I am aware due to any shortage in spares.


Thanks. I wasn't sure but I wondered mostly because I had a vague sense that the conversion was performed at about the same time as Type 42s started to leave the Fleet. It can't have been a direct transplant of systems required for stretched Type 42 hulls, because IIRC the Invincibles' missile magazines were larger and probably wouldn't fit.


Had I ever been the captain of an Invincible, it would have pleased me to keep the Sea Darts - it'd be nice to know that even if all my escorts were sunk or diverted, I still had some area air defence capability. Surely even the Harrier has limits to the weather it can fly in and the UK carriers were mostly Atlantic/North Sea assets, yes?


(The same argument applies to carriers having battleship escort in World War 2 - the torpedo bomber has far greater range and potentially greater lethality than the 14 to 16 inch gun, but the battleship can steam and fight and defend the carrier from enemy capital ships in weather which would make it impossible to launch a defensive strike in time, especially in the days when radar was not so hot and an enemy ship could suddenly appear out of the mist. See also "Norwegian Campaign".)

Offline TomS

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Re: Australian Invincible
« Reply #4 on: November 07, 2014, 10:22:53 am »
The RN Invincible refits added about 8% to the total flight deck area (including both the Sea Dart area and the forecastle area originally intended for Exocet).  This has a surprisingly large impact on flight deck operations. 
 
I understand the Sea Dart magazines also got repurposed as air ordnance magazines, which was a big deal because the Invincibles have rather small magazines to begin with.  They were built around expected ordnance usage by ASW helos and air-defense fighters.  Ground attack missions and increase use of smart weapons called for larger magazines.

Offline pathology_doc

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Re: Australian Invincible
« Reply #5 on: November 07, 2014, 11:48:21 am »
The RN Invincible refits added about 8% to the total flight deck area (including both the Sea Dart area and the forecastle area originally intended for Exocet).  This has a surprisingly large impact on flight deck operations.


I'm by no means familiar with the deck manipulation aspect of through-deck-cruiser air operations, but I can sort of understand how having just a little bit more space in all the right places can make a disproportionate difference.
 
Quote
I understand the Sea Dart magazines also got repurposed as air ordnance magazines, which was a big deal because the Invincibles have rather small magazines to begin with.  They were built around expected ordnance usage by ASW helos and air-defense fighters.  Ground attack missions and increased use of smart weapons called for larger magazines.


 ;D  How convenient to have that space which just happens to already be designed for the safe storage of rocket motors, high explosives, etc. I guess that removing the no-longer-necessary illuminator radars for the Sea Darts would have helped a fair bit with topweight/metacentric height issues too, especially if you're going to add weight in the way of extra flight deck structure and the necessary bracing.

Offline Abraham Gubler

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Re: Australian Invincible
« Reply #6 on: November 07, 2014, 05:51:43 pm »
The Sea Dart seems to get a lot of intention when Invincible being sold to Australia is retrospectively looked at but it wasn't a big issue for the RAN. When they were looking at a carrier in the 1970s to build in Australia to replace the Melbourne an area air defence missile system was not a requirement. So when Vickers pitched a design based on the Invincible they didn't include one. Neither did G&C with their sea control ship nor Ingalls with their light carrier. The later was called a modified Iwo Jima but it only shared the hull with this ship.


When the offer came through to sell the actual HMS Invincible it was going to come with the Sea Darts. Removing the system was not part of the plan to Australianise the ship. Sea Dart was in a different class to the SM-1MR operated by the RAN on the DDG and FFG at the time. It was comparable to the SM-1ER and the two systems would have worked very well together providing a RAN task force layered air defence. It is also important to understand at the time the RAN had no program to buy Sea Harriers. Clearly they wanted and needed them but at first HMAS Australia (ex Invincible) was only going to operate Sea Kings with the Skyhawks and Trackers flying from shore until VTOL replacements for both types were acquired. A Sea Harrier, Sea Dart, Standard three layer air defence system would have been very effective at the time.
"There is a tendency in our planning to confuse the unfamiliar with the improbable." Thomas Schelling

Offline pathology_doc

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Re: Australian Invincible
« Reply #7 on: November 10, 2014, 08:11:48 am »
Thanks for that. I was unaware that Sea Dart was actually that good in performance terms.


It seems that HMAS Australia would have been a true large ASW helicopter cruiser in the mould of the large Italian Terrier-armed ships, at least until such time as a Harrier component was acquired, except that the Italian ships also bristled with 76mm rapid-fire guns that would have added a well-needed inner line of defence - not ideal or true anti-sea-skimming-missile CIWS in the Phalanx sense, but certainly better than nothing.


For a small navy like the RAN, too, the extra area-defence SAM system would make a HUGE difference.

Offline Abraham Gubler

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Re: Australian Invincible
« Reply #8 on: November 10, 2014, 02:07:52 pm »
Thanks for that. I was unaware that Sea Dart was actually that good in performance terms.

Sea Dart Mod 0 max range = 40 nm
SM-1MR Block V max range = 25 nm
 
It seems that HMAS Australia would have been a true large ASW helicopter cruiser in the mould of the large Italian Terrier-armed ships, at least until such time as a Harrier component was acquired, except that the Italian ships also bristled with 76mm rapid-fire guns that would have added a well-needed inner line of defence - not ideal or true anti-sea-skimming-missile CIWS in the Phalanx sense, but certainly better than nothing.

Both ships, Invincible and Vittorio Veneto, were designed for the same mission: being the centre of an ASW task force. The difference in designs is because of their different operational theatres. The Invincible was designed for the North Atlantic and the Vittorio Veneto for the Mediterranean. So the former needed much better sea keeping and a capability to shoot down enemy long range patrol planes (hack the shad). The later didnít need these capabilities but in their place needed heavy armament for short range engagement of Ďsurpriseí threats.
 
The RAN however wanted Invincible to be a conventional aircraft carrier. The only reason they wouldnít have flown fighters from its deck from day one is because they didnít have a suitable aircraft. But it would have become the RANís no. 1 priority after transfer of the ship and as soon as money was available a squadron would have been purchased. Until then the Skyhawks would have kept flying.
 
For a small navy like the RAN, too, the extra area-defence SAM system would make a HUGE difference.

Sea Harriers would have made the most difference. But the whole point of putting a SAM system onto the carrier was to improve its self defence capability with spread out task force sailing formations. It would also enable in the RANís context a good upper layer over the top of the SM-1M%.
"There is a tendency in our planning to confuse the unfamiliar with the improbable." Thomas Schelling

Offline pathology_doc

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Re: Australian Invincible
« Reply #9 on: November 11, 2014, 05:45:42 am »

Sea Harriers would have made the most difference. But the whole point of putting a SAM system onto the carrier was to improve its self defence capability with spread out task force sailing formations. It would also enable in the RANís context a good upper layer over the top of the SM-1MR.


In terms of the carrier's performance in isolation, yes - putting Harriers on is the best thing that ever happened to the through-deck cruisers. I can't remember the purchase timeline exactly but Invincible must have been under consideration at a time before any of the Perry-class frigates entered Aussie service, and the extra hull with an area-defence weapon system would have added massively to the Navy's flexibility in terms of putting such systems to sea. That's what I was mostly getting at with that comment.


The one thing I'm not completely sure of before I shoot my mouth off about DDG vs. FFG capabilities regarding guided missiles is how many channels of fire the Perry-class ships had for their Standard systems (when they were still using SM-1MR). I always thought one, but I vaguely recall reading somewhere that the gun FCS radar can be used as a secondary illuminator, which gives them two and would make them the equal in that respect (and that respect alone) of the DDGs and Invincible.


ETA:
http://en.wikipedia.org/wiki/Adelaide-class_frigate


So it looks like they were in contention an aeon before Invincible was considered, and some of what I wrote above is utter garbage. Interesting in light of what I hypothesised above that mention is made of retrofitting SM-1MR to Type 42 hulls!!!!!
« Last Edit: November 11, 2014, 05:52:11 am by pathology_doc »

Offline TomS

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Re: Australian Invincible
« Reply #10 on: November 11, 2014, 07:50:13 am »
Yes, the FFGs were actually in service already by the time the Invincible decision was made. 


As of 1981, Janes was still saying that the preferred option seemed to be "a gas-turbine version of the US Navy "Inchon" [Iwo Jima] class with a ski jump."  That ship would not have had any area SAM at all, so the presence of Sea Dart on Invincible would have been a bonus, but not a requirement.  I suspect that if they had gone with a purpose-built Invincible (rather than a used ship), Sea Dart would have been left off as an economy.  By that point, the RAN would have had at least seven ships with SM-1, including the three DDGs with proper 3-d radar (the FFGs had only 2-d search radar). Sea Dart would have been nice, but an expensive option. 


The plan c. 1981 also called for a VSTOL aircraft to be selected in 1983, after the carrier selection in 1982.  The only choice, I think, would have been between Sea Harrier (with radar) and Harrier II (with more payload). 




Offline pathology_doc

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Re: Australian Invincible
« Reply #11 on: November 11, 2014, 12:10:02 pm »
The plan c. 1981 also called for a VSTOL aircraft to be selected in 1983, after the carrier selection in 1982.  The only choice, I think, would have been between Sea Harrier (with radar) and Harrier II (with more payload).


IOW a Big Call between an interceptor with secondary strike capability and a strike aircraft with dogfight capability but not necessarily optimised for the interceptor role. In the context of an ASW/escort group leader which is a nation's only carrier, and with a limited number of aircraft on the ship, I'd be biased towards the interceptor, quite frankly. That being said...


[1] There has to be a critical number beyond which having a mixture of types would start making sense, but one baby flat-top of the sort Australia would have been operating isn't enough to take that many to sea.


[2] It's arguable whether the Brits would have operated a mixture of types at the Falklands if the RAF hadn't already been operating the land-based Harrier in significant numbers. It's fortunate indeed that the RN had the option of reinforcing its carrier-based fighters with a land-based aircraft which was the same in all essential respects.

Offline Abraham Gubler

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Re: Australian Invincible
« Reply #12 on: November 11, 2014, 04:37:08 pm »
In terms of the carrier's performance in isolation, yes - putting Harriers on is the best thing that ever happened to the through-deck cruisers. I can't remember the purchase timeline exactly but Invincible must have been under consideration at a time before any of the Perry-class frigates entered Aussie service, and the extra hull with an area-defence weapon system would have added massively to the Navy's flexibility in terms of putting such systems to sea. That's what I was mostly getting at with that comment.

For the RAN the decision to add Tartar (later renamed SM-1MR in the move to digital processors) to the new destroyer was made around 1970. This was the DDL project which was conceived as a primary Ďmaritime interdictioní mission vessel that could also be built as an ASW vessel. Maritime interdiction was the name for destroying small boats and coastal shipping and was based on the RANís experience against the Japanese in WWII, Indonesia during the Confrontation and North VietNam during that war. Around 1970 the RAN realised that the best platform for this mission was an armed helicopter. Therefore the most efficient way of doing the mission was to have smaller numbers of ships flying larger numbers of helicopters rather than larger numbers of DDLs (aka frigates/corvettes) without helicopters. Since the DDL ship grew in size and importance to operate two helicopters it was decided it needed Tartar for self defence.
 
Rather than build the DDL locally the then new Whitlam Government decided to order the then PF (Patrol Frigate later renamed the FFG-7, Oliver Hazard Perry class) from the USA. On paper these ships were similar to the DDL having Tartar-D and flight deck and hangars for two similar sized (<14,000 lb) helicopters. Which is how the RAN got the first four FFGs. The later two came from the Australian Frigate Project which was a plan from around 1981-82ish in order to kickstart warship building in Australia after the DDL cancellation killed it off. The original plan for this program was to initially build two and upwards of 10 ships from the mid to late 1980s. The final decision on this project was actually made at the same time that the Invincible sale deal was going through, being cancelled. The type of ship to be built was down to between the Dutch M class (later called the Karel Doorman) and the FFG-7. The later was chosen only because it was considered a better class to be built at the Australian shipyard because it had been designed as amobilisation, mass production frigate by the USN so had high tolerances for local differences.
 
Anyway because the RANís air threat risk opersting in the South Pacific and Indian Ocreans was far lower than the RNís risk operating in the North Atlantic there was no need to provide their new Melbourne replacement carrier with a high end self defence missile system like Tartar. It was hoped that the carrier borne fighters and the DDG/FFGs operating as pickets would Ďpickí anything off before it got to close. The RN facing massed BACKFIRE attacks needed a Sea Dart on every ship to survive (or more likely two Sea Darts!).
 
The one thing I'm not completely sure of before I shoot my mouth off about DDG vs. FFG capabilities regarding guided missiles is how many channels of fire the Perry-class ships had for their Standard systems (when they were still using SM-1MR). I always thought one, but I vaguely recall reading somewhere that the gun FCS radar can be used as a secondary illuminator, which gives them two and would make them the equal in that respect (and that respect alone) of the DDGs and Invincible.

The FFG has two air engagement channels for SM-1MR via the Mk 92 Mod 2 FCS. However compared to the Mk 74 FCS system on the DDG supported by 3D radar it canít acquire a track as quickly nor illuminate with as much power. So engagement range in less than ideal circumstances will be lower.
 
Interesting in light of what I hypothesised above that mention is made of retrofitting SM-1MR to Type 42 hulls!!!!!

The Australian forces often put all sorts of ridiculous options into papers for consideration by the Government. Type 42s with Tartar would be one of them. The DDL submission to cabinet also considered Finish corvettes in the mix!
"There is a tendency in our planning to confuse the unfamiliar with the improbable." Thomas Schelling

Offline Abraham Gubler

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Re: Australian Invincible
« Reply #13 on: November 11, 2014, 04:40:45 pm »
As of 1981, Janes was still saying that the preferred option seemed to be "a gas-turbine version of the US Navy "Inchon" [Iwo Jima] class with a ski jump."  That ship would not have had any area SAM at all, so the presence of Sea Dart on Invincible would have been a bonus, but not a requirement.  I suspect that if they had gone with a purpose-built Invincible (rather than a used ship), Sea Dart would have been left off as an economy.

Before the HMS Invincible offer was put on the table the RAN had shortlisted the new carrier design to Gibbs & Cox with the SCS (Prince of Asturia) and Ingalls with the LPH hull turned into a carrier (Inchon/Iwo Jima). There was never a requirement for a self defence missile system just CIWS for these ships.
"There is a tendency in our planning to confuse the unfamiliar with the improbable." Thomas Schelling

Offline Abraham Gubler

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Re: Australian Invincible
« Reply #14 on: November 11, 2014, 04:58:01 pm »
IOW a Big Call between an interceptor with secondary strike capability and a strike aircraft with dogfight capability but not necessarily optimised for the interceptor role. In the context of an ASW/escort group leader which is a nation's only carrier, and with a limited number of aircraft on the ship, I'd be biased towards the interceptor, quite frankly. That being said...

The Sea Harrier is NOT an interceptor with a secondary strike capability. It actually has superior strike capability than a AV-8B. It was always designed as a multi role strike fighter. In the Falklands most of its missions were combat air patrol because that was the need but they still carried out a series of important strike missions and could have flown more if not for conflicting tasking requirements with the RAF (ie politics!). The AV-8B can carry more stores further but the Sea Harrier is faster and before the Block 2 AV-8Bs with the APG-65 was a far superior naval aircraft.
 
[1] There has to be a critical number beyond which having a mixture of types would start making sense, but one baby flat-top of the sort Australia would have been operating isn't enough to take that many to sea.

Two types of Harrier would never make sense for the RAN. The AV-16 would have been ideal but it never went ahead. And even if it did it was the RNís preference for the Sea Harrier role.
 
[2] It's arguable whether the Brits would have operated a mixture of types at the Falklands if the RAF hadn't already been operating the land-based Harrier in significant numbers. It's fortunate indeed that the RN had the option of reinforcing its carrier-based fighters with a land-based aircraft which was the same in all essential respects.

The GR.1 Harriers were only sent south because the UK Forces ran out of Sea Harriers. If they had another 10-12 then they would have been sent even if flown by RAF personnel.
 
As an addition to this discussion I was thinking last night that the best option available for the RAN at this time if the Government had been interested in maintaining the carrier force was not the HMS Invincible but the backup offer. When the UK requested that they keep this carrier their plan was to have a three Invincible class force to maintain two in service post Falklands War (lesson learnt). Invincible was the dog of the class having very bad engine vibration issues and the entire class while a nice modern ship with great systems was very badly designed to be a carrier.
 
When the RN asked to keep the Invincible they offered the Hermes in its place being available from 1985 (when Ark Royal would be online). Hermes was turned down by the Australian Government but would have made a much better ship for the RAN to replace Melbourne. For starters it was much cheaper being later sold to India for £60 million compared to £175 million deal for Invincible. The sale included a one year refit which Iím not sure of the specifics but I assume must have included reboilering considering how long India has kept it in service since. The light fleet carriers have proven themselves to have excellent hull life if properly maintained. Hermes was also larger and a much better carrier for aircraft and had a good ASW systems fit.
 
For the RAN the money saved between Hermes and Invincible could have been used to fit a brand new US spec air warfare radar and combat management system (NTU level) and provide the ship with CIWS and a thorough systems refresh (and reboilering, propulsion zero houring). But most interesting the ship could have been reverted to a conventional catapult and arrestor gear carrier. With the removal of the ski jump and refit of such gear including two new C13 catapults (but with limited length, 150 and 175 feet) this ship could operate the RANís legacy air wing. There would be no need to replace the Skyhawk and Tracker both of which had plenty of remaining life and established workforces.
 
Such a ship could easily operate an air wing of 12 A-4Gs, 12 S-2Gs and 12 Sea Kings. It could be in service by 1988 (commissioning of HMAS Australia during the Bicentennial Year) and remain in service until 2013 (RAN Centenary). The air wing could be modernised with the Skyhawks either going through something like the RNZAF Kahu upgrade or being replaced by Australian built F/A-18 Hornets (12 of which could fit onboard). The Trackers still had over 20,000 hours of flying life left on them and had modern digital acoustic processors. With the Grumman/Garret turboshaft upgrade they could be in service until the carrier needed replacing. While E-2 Hawkeyes might be a big too big for the Hermes the Tracker could be upgraded for AEW. Either Boneyard E-1 Tracers with a new radar or a Sea King AEW modification to the S-2G combined with turboshafts would provide excellent fleet AEW.
 
Such an option would have been a low cost, low risk way of maintaining the RANís carrier force and avoiding the need to rebuild the first three FFGs for ASW helicopters and buying 16 very expensive Seahawks to retain some kind of standoff ASW capability in the fleet.
 
 
« Last Edit: November 11, 2014, 05:01:45 pm by Abraham Gubler »
"There is a tendency in our planning to confuse the unfamiliar with the improbable." Thomas Schelling