A hypothetical carrier buy for the RAN?

[Abraham Gubler]

At this point, I suspect the best we will manage is to agree to disagree re: viability of F-35B ops from the LHDs.

The Canberra class LHD can operate F-35Bs and in numbers. It has no deficiency in STOVL operations compared to a carrier like the Invincible class. It has the right flight deck arrangements, maintenance and so on and can carry the consumables needed to sustain an air wing similar in size (if not a little bit bigger) to an Invincible class.

However it can’t do this while being an amphibious assault ship and compared to a purpose built carrier it has a range of deficiencies. Even a half squadron of six F-35Bs would severely impede on the amphibious ready group especially the rotary wing element. But as designed by Navantia and the Spanish Navy this class of LHD can swing role between an amphibious assault ship and a carrier ship.

But even when in the carrier configuration the LHD is a lot slower than it should be so it can’t operate at normal fleet manoeuvre speeds. Most importantly it is not designed as a fleet combat unit especially in terms of ASW. The LHD has an extremely high acoustic profile and would significantly affect the way a normal carrier task force would operate.

While the argument for a third LHD operating as a carrier may be attractive it does not offer any real advantage over building a role specific light carrier/sea control ship and quite a few disadvantages. Clearly seen in that the Spanish won’t be replacing Principe de Asturias with a second LHD.

 

[weasel1962]

Re:

I was going to point that out.: The ski jumps were kept IIRC because the ship and fore structure would have to be re-designed to remove it, and there were concerns about both cost and risk in doing so. In the end it was felt that it less costly and risky to keep the ski jump, than to have it removed and have an extra spot for a helicopter to land.

Thanks! (incl to SASWanabe) So that's even less "cost" involved.

As for AEW being a 'white elephant', I find that a rather funny position. After all, an AEW like the E-2C Hawkeye AWACS has a radar detection radius of 200+ miles, and is able to track several thousand contacts. That sort of increase in a task force sensor footprint vs. air/surface search radars aboard ship is enormous.

I'm just thinking. If let's say a wedgetail can detect an inbound MPA, what can the task group do about it? The SM-2s blk 4 or SM-6s have pretty good range (160-320km) but currently, its only SM-2 Blk IIIA/Bs in inventory with a range up to 90nm (167km).

The US Navy -- Fact File

Once detected, will the aggressor be able to launch anti-ship missiles beyond the range of the standards? Eg using existing 400+km ranged YJ-62s, 2XX km ranged YJ-83s or 290km ranged Yakhonts/Brahmos...

Standards/Aegis vis-a vis detection, could the MPA spot the group before it enters striking range? Not to mention that the Awacs could itself be a big signboard for a search party.

Its gets trickier with UAVs (or worse stealth UAVs) where its going to be pretty expensive trading limited numbers of SM-2s for cheap UAVs. Shooting one down is like telling everyone I am here.

Also, how safe would a single wedgetail be out a few thousand nautical miles out and how much loiter time it would need (not to mention tanker resources if that is the intent)? At least for a Nimitz CBG, there's air cover to provide defensive CAP.

At this point, I suspect the best we will manage is to agree to disagree re: viability of F-35B ops from the LHDs.
-Cheers

Thanks for the civil discourse! Your points raised are not without merit.

 

[Jaimito]

The Canberra class LHD can operate F-35Bs and in numbers. It has no deficiency in STOVL operations compared to a carrier like the Invincible class. It has the right flight deck arrangements, maintenance and so on and can carry the consumables needed to sustain an air wing similar in size (if not a little bit bigger) to an Invincible class.

However it can’t do this while being an amphibious assault ship and compared to a purpose built carrier it has a range of deficiencies. Even a half squadron of six F-35Bs would severely impede on the amphibious ready group especially the rotary wing element. But as designed by Navantia and the Spanish Navy this class of LHD can swing role between an amphibious assault ship and a carrier ship.

But even when in the carrier configuration the LHD is a lot slower than it should be so it can’t operate at normal fleet manoeuvre speeds. Most importantly it is not designed as a fleet combat unit especially in terms of ASW. The LHD has an extremely high acoustic profile and would significantly affect the way a normal carrier task force would operate.

While the argument for a third LHD operating as a carrier may be attractive it does not offer any real advantage over building a role specific light carrier/sea control ship and quite a few disadvantages. Clearly seen in that the Spanish won’t be replacing Principe de Asturias with a second LHD.

I doubt the acoustic profile is "extreme" of the Lhd, compared to a "normal" carrier taskforce operation, a Nimitz sends 200 mwatts to 4 propellers, the Canberra send 20 mwatts in 4 propellers, Nimitz is going to have a higher acoustic profile, it is 10 times more powerful, more "violence", "noise".
You can put doubts on the pods and their "twin" propellers but the sea trials for Jc1 has been passed, that means it acomplishes the Spanish Navy requirements in terms of "acoustic profile".

Take into account that jets only use the runway for landing, as soon they land they can be moved, and just move them again to launch them. Once you have an schedule of operation defined, it you just put 2 or 3 jets in air, with an scheduled endurance +- 3 hours. you might have maybe 60 or 70 % of time (3 h.) with the runway free for helos. Its the same principle as for putting in air more than 6 jets, you have to programme it, but instead more jets just more helos.
I am not saying it is not, maybe, more complex, but 6 jets and 10 helos, for example, i don´t rule they can be compatible in simultaneous ops., for me it had be studied.

 

[Bonza]

I doubt the acoustic profile is "extreme" of the Lhd, compared to a "normal" carrier taskforce operation, a Nimitz sends 200 mwatts to 4 propellers, the Canberra send 20 mwatts in 4 propellers, Nimitz is going to have a higher acoustic profile, it is 10 times more powerful, more "violence", "noise".

While I don't have the answers myself, I would be very careful about assigning acoustic signatures on the basis of power output alone. There are a lot of other factors at play when it comes to acoustic warfare - I hope GF, Abe or one of the Navy guys on here can give more information because I won't pretend to be an expert on the topic, but I do know that the acoustic signature of a warship cannot be reduced to something as simple as more power = more noise. I would guess that propellor design, hull design, performance envelopes and many other things would come in to it.

 

[Jaimito]

Several points for consideration.


Without significant modification work done in a dock to re-role one of the LHDs from an LHD into some sort of CHL/V, then the Canberra-class LHD is going to be limited in terms of space available to dedicate to supporting aircraft (fast jet and helicopter) operations. While I have been attempting to relocate where I recall seeing the figure of 800 tons aviation fuel available aboard the LHD, it is germane to note that the larger Wasp-class LHD in service with the USN can carry ~1,200 tons of JP-5 aviation fuel. A Wasp-class LHD also routinely operates ~23 helicopters of various types, and up to 6 AV-8 Harriers sometimes as well, depending on mission.
It is also worth noting that a Nimitz-class CVN carries ~10,000 tons (3 mil. gal.) of aviation fuel aboard, with supplies sufficient to sustain operations for 90 days. That is for a CVN which typically operates with ~64 fixed and rotary aircraft, but can operate up to ~100 total.

Significant work dock is: redistribute fuel, spares, weapons according to what the Lhd carries. It wil take some hours? some days? Not really important.

Lastly the argument that 6 F-35Bs are automatically better than none is not true. It becomes a matter of doctrine and the types of operations that are engaged in. That is part of the reason why a RAN carrier is at this point a, "nice to have, not something worth spending the money on yet..." sort of capability. A properly kitted out CV, with the approriate air group aboard and of course the other vessels and kit that the ADF already has planned, would certainly give Australia more options. At present, the RAN has doctrine for operating vessels in air threat environments, injecting six ADF fast jets (whether RAAF or RAN FAA) would just introduce additional complications to how area air defence would be managed around a task force. Or even worse still, it could result in ships or a task force being deployed to a threat environment where the air defences were insufficient or unsuitable.

Ask the Us Marines why the carry 6 jets (or more) in many missions, for sea issues or for support in land projection.

Given that the RAN is only going to have two LHDs, and that they are the type of asset which is going to see regular use, and that they are really not suited for fast jet ops, can we inject some semblance of reality here and drop arguments to base F-35Bs off them?

Ok Ran´s Lhd are not thought for fast jet ops, but that doesn´t mean that Ran could change her mind and change whatever needs so match the Jc1, which is presented by Navantia as "aircraft carrier with amphibious capability", and note that first words from Navantia to describe the Jc1 is "AIRCRAFT CARRIER" and after that they mention "amphibious" and "sealift".

 

[SASWanabe]

Ok Ran´s Lhd are not thought for fast jet ops, but that doesn´t mean that Ran could change her mind and change whatever needs so match the Jc1, which is presented by Navantia as "aircraft carrier with amphibious capability", and note that first words from Navantia to describe the Jc1 is "AIRCRAFT CARRIER" and after that they mention "amphibious" and "sealift".

i think it has been pointed out but the LHDs are alot different to Jc1 they only look the same from the outside

 

[Abraham Gubler]

i think it has been pointed out but the LHDs are alot different to Jc1 they only look the same from the outside

They look the same from the inside too. The significant difference between the two is in the C2 side of things. Certainly a RAN LHD will be capable of operating in a similar carrier mode as a Spanish LHD. Of course we don't have the air wing but say the USMC was to pony up a VMFA it could be accomodated.

 

[Sea Toby]

They look the same from the inside too. The significant difference between the two is in the C2 side of things. Certainly a RAN LHD will be capable of operating in a similar carrier mode as a Spanish LHD. Of course we don't have the air wing but say the USMC was to pony up a VMFA it could be accomodated.

But if the US DOD cancels the F-35B, the AV-8Bs won't be around much longer... The US Navy had intentions of building along with the British many of the Bs before the Cs to replace old worn out Harriers... The British have already given up on the Bs, and it looks as if the US Marines will follow within two years unless Lockheed Martin pulls a rabbit out of the hat...

Of course, I would expect the Marines would find a way to arm the Ospreys to provide ground air support if the Bs are cancelled... But we'll cross that bridge at a later date...

 

[Abraham Gubler]

But if the US DOD cancels the F-35B, the AV-8Bs won't be around much longer... The US Navy had intentions of building along with the British many of the Bs before the Cs to replace old worn out Harriers... The British have already given up on the Bs, and it looks as if the US Marines will follow within two years unless Lockheed Martin pulls a rabbit out of the hat...

Of course, I would expect the Marines would find a way to arm the Ospreys to provide ground air support if the Bs are cancelled... But we'll cross that bridge at a later date...

The cancellation of the F-35B is still a very unlikely event. Also it does not mean the cancellation of STOVL capability. The UK DID NOT give up the F-35B they moved to the F-35C so they could immediately abolish their Harrier force and move to a joint naval air wing with the French in ten years time. Nor is the F-35B in as much trouble as people are making out.

So back in the real world there is still a solid future of STOVL operations from carriers and LHDs for some time. Most likely this will be the F-35B or another aircraft to replace the AV-8B in the 2020s.

 

[weasel1962]

Re:

While I don't have the answers myself, I would be very careful about assigning acoustic signatures on the basis of power output alone. There are a lot of other factors at play when it comes to acoustic warfare - I hope GF, Abe or one of the Navy guys on here can give more information because I won't pretend to be an expert on the topic, but I do know that the acoustic signature of a warship cannot be reduced to something as simple as more power = more noise. I would guess that propellor design, hull design, performance envelopes and many other things would come in to it.

Academically and in simple terms, I note citations of 4 major factors. Speed, tonnage, prop tip speed and number of prop blades.

Power output can be considered an indirect proxy of the above factors. Heavier ship with less power = less speed. However agree with Bonza as power alone is not the sole factor.

Variables can include the way the ship moves in water, depth of water, water temp, hull/machinery vibration/engine harmonics, use of damping material and a whole host of other variables.

The above is based on readings relating to radiated sound spectrum surveys for commercial vessels. I'm probably missing quite a bit more variables but I'll leave it as that. I do note some papers stating that at higher speeds, the propellor noise is the main culprit of acoustic sounds.

Militarily, I would guess that some of the items eg construction materials and tighter construction techniques to reduce vibration, ship design features that lessen noise creation would reduce noise signatures and probably explain why it cost more to build military vessels.

imho, a sonar operator with actual experience of listening to both would actually be the only person to comment since sonar is the main acoustic device to pick up the signatures. With the ships built by 2 differing countries and 2 differing yards, no engineer will have experience with both types of vessels.

 

[Jaimito]

Academically and in simple terms, I note citations of 4 major factors. Speed, tonnage, prop tip speed and number of prop blades.

Power output can be considered an indirect proxy of the above factors. Heavier ship with less power = less speed. However agree with Bonza as power alone is not the sole factor.

Variables can include the way the ship moves in water, depth of water, water temp, hull/machinery vibration/engine harmonics, use of damping material and a whole host of other variables.

The above is based on readings relating to radiated sound spectrum surveys for commercial vessels. I'm probably missing quite a bit more variables but I'll leave it as that. I do note some papers stating that at higher speeds, the propellor noise is the main culprit of acoustic sounds.

Militarily, I would guess that some of the items eg construction materials and tighter construction techniques to reduce vibration, ship design features that lessen noise creation would reduce noise signatures and probably explain why it cost more to build military vessels.

imho, a sonar operator with actual experience of listening to both would actually be the only person to comment since sonar is the main acoustic device to pick up the signatures. With the ships built by 2 differing countries and 2 differing yards, no engineer will have experience with both types of vessels.

I replied wrt Abraham was referring to the propellers, as far i understood he was referring to the "twin" propeller each pod has, not the rest of the ship, that is envelopes for the engines, the transmission, for example this, the transmission and all the reductor chainings, in the Lhd because it works with pods and is electric is going to be in that aspect less noise than more mechanical transmissions.

But people see the something rare with the twin propellers and because they are very close in each pod maybe they think of water violently separated between both propellers in the same pod. But the reality is that they are syncronized.

See this way, you send 200 mwatts because you need to move much more water through the propellers, instead of moving 24000 t (carrier mode) or 27000 t. of displacement for the Lhd, you are moving 100000 t. or a bit less, of corresponding water via propellers, and water just itself makes noise. For example rumrumrum. Energy transforms, it doesnt disappear.

At the same time if you see how the pods are enveloped each one in a channel of water under the ship, you see that actually they are less exposed out of the shape of the ship than normal propellers with mechanical transmission, so maybe reducing certain type of echoe.

But those things are different to what i pointed out of transmitting 20 mwtts to propellers or 200 mwtts to bigger propellers, or faster propellers, etc.

 

[Abraham Gubler]

I replied wrt Abraham was referring to the propellers, as far i understood he was referring to the "twin" propeller each pod has, not the rest of the ship, that is envelopes for the engines, the transmission, for example this, the transmission and all the reductor chainings, in the Lhd because it works with pods and is electric is going to be in that aspect less noise than more mechanical transmissions.

I was not referring to the twin propellers. Trying to over think capability from a limited understanding of inputs is not a good idea, but extremely popular in these forums. The problem with acoustics is the pod. This pod contains the motor that propels the propellers. In non pod ships these motors – be they electrical or mechanical - are contained within the hull. In the pod there is no way to isolate motor noise from the ocean. This is no problem for the pod as a commercial motor it is designed for hydrodynamic purposes not acoustic. But in a military vessel it is a major issue. This is one of the reasons the RAN is rapidly upgrading stand off ASW capability to push back the threat from the LHD.

 

[Volkodav]

I was not referring to the twin propellers. Trying to over think capability from a limited understanding of inputs is not a good idea, but extremely popular in these forums. The problem with acoustics is the pod. This pod contains the motor that propels the propellers. In non pod ships these motors – be they electrical or mechanical - are contained within the hull. In the pod there is no way to isolate motor noise from the ocean. This is no problem for the pod as a commercial motor it is designed for hydrodynamic purposes not acoustic. But in a military vessel it is a major issue. This is one of the reasons the RAN is rapidly upgrading stand off ASW capability to push back the threat from the LHD.

Which I suppose is one of the reasons why the QE2, Type 45 etc have their electric motors inboard driving the propellers via short shafts. The motors can be adequately rafted and isolated from the ocean.

Although EB have been looking at podded propulsers on some of their future sub concepts so there must be a way to facilitate pods and acoustic performance. Probably just not seen to be worth the time effort and cost to do it for a surface platform as there are perfectly adequate alternatives available.

 

[Abraham Gubler]

Which I suppose is one of the reasons why the QE2, Type 45 etc have their electric motors inboard driving the propellers via short shafts. The motors can be adequately rafted and isolated from the ocean.

Absolutely. Pods are not considered milspec though there are some ideas for naval use isolated pods no pod maker seems to be putting serious money into developing one. Certainly the COTS pods used on both the JCI and Mistral class LHDs are just commercial items. Which is why these ships are built to commercial standards and why the JCI is considered a cruise ship from the waterline down.

But any pod – even an isolated one – will also have the motor highly exposed to damage and not just from enemy weapons. You run aground in a conventional ship and you just need a new propeller, you run aground with a podded ship and you need a new motor. While pods can be easily changed the more aggressive sailing of military ships compared to commercial cruise liners significantly increases the risk of motor damage. Especially since pods tend to have a much higher draft than conventional propeller arrangement.

 

[Volkodav]

I can't help but equate deploying half a dozen F-35Bs on an LHD to fitting a turret with a 76-105mm gun to an APC (wheeled or tracked). The end result sort of looks like a tank and on paper matches the gun power but it most definitely is not a tank and things will end very badly very quickly if you ever try to use it as a tank. You have the gun but that’s it, the rest of the balanced platform, developed over decades of battle experience is missing so what you end up with is limited and vulnerable. You are much better off deploying a tank or purpose designed armoured car that isn’t compromised through being designed for another role.

Same with the LHD option, you can carry the aircraft but that about it and you will be severely limiting the utility of the F-35B by tying it to an amphib. You lose amphibious capability to accommodate the F-35s and their minimum support requirements while limiting the performance of the F-35’s through not possessing the full spectrum of support capabilities.

In particular if you are talking about building a third LHD to serve as a carrier a much better option would be a purpose designed carrier. Perhaps a little small and too limited, but it could be argued that something akin to the RTNs HTMS Chakri Naruebet would be a better option if combined with the purchase of a Bay or similar to fill the sealift requirement.

While not ideal a small purpose designed carrier (CVS?) carrying a single sqn each of F-35s, ASW helos and an AEW and a CSAR detachment, would likely be a better and more versatile investment. Design it for fleet speeds, i.e. 18 kt cruise speed / 27kt + max sustained, and endurance 6000Nm +. Incorporate the same combat system as the ANZAC replacements as well as CEC and a decent self defence capability.

There will still only be a half dozen F-35 in peace time and a dozen as required, the big advantage would be the AEW, ASW and CSAR helos added to any task group this ship is assigned to.

Logistics, easy form something akin to the RFA to save costs while tripling the number of fat ships using conversions along the lines of Sirius, perhaps including the sealift ship as well. Maybe look at incorporating operation and support of Customs fleet within this organisation too.

 

[Jaimito]

I was not referring to the twin propellers. Trying to over think capability from a limited understanding of inputs is not a good idea, but extremely popular in these forums. The problem with acoustics is the pod. This pod contains the motor that propels the propellers. In non pod ships these motors – be they electrical or mechanical - are contained within the hull. In the pod there is no way to isolate motor noise from the ocean. This is no problem for the pod as a commercial motor it is designed for hydrodynamic purposes not acoustic. But in a military vessel it is a major issue. This is one of the reasons the RAN is rapidly upgrading stand off ASW capability to push back the threat from the LHD.

The electrical engine is inside the ship, and it has a big "envelope", a big capsule, exactly a ring from the ship, where it is supported, round it. But the thing is that it is totally electrical, why modern subs like the S80, Scorpene, U-boats, why the have totally electrical engines? Are they noisy?


My personal view:The pod it has the head inside the ship, where there is the electrical engine, below the head there is the other part that can be changed if you damage the whole part that is out of the ship, you don´t need to change the head if you dont damage it. If you break a lip you can change it or the whole propeller as well indepently of the body that has the pod transmission if you don´t damage it. As the rigourous Spanish Navy did in the sea trials, just the propeller or lip shape, not the body pod or the electrical engine. The draft of the ship is just +-7.2 loaded.

I paste:

"Advantages
•Substantially higher efficiency than Z drives with a single propeller
•Higher power transmission possible than with a single propeller
•Lower risk of cavitation due to the lower propeller load
•Lower pressure fluctuations and noise emissions
•Lower mechanical losses than contrarotating two-propeller systems
•High reliability due to the small number of moving parts
•Fully steerable (360°)
•High variability of the characteristic curve meets a wide range of operational requirements up to speeds of 21 knots
•Particularly suitable for installations permitting only limited propeller diameters (restricted draught or required tip clearance) "

It´s Siemens Schottel who is saying this above wrt the twin propellers.


Edit: the Jc1 is done to military standards, not commercial standards but also environmental and many standards... (video from Navantia).

 

[Abraham Gubler]

The electrical engine is inside the ship

No it isn’t. The electrical generator is inside the ship but the motor that turns the screws is inside the pod. See the attached patent image. Add this to your list of epic fails.

 

[weasel1962]

I can't help but equate deploying half a dozen F-35Bs on an LHD to fitting a turret with a 76-105mm gun to an APC (wheeled or tracked). The end result sort of looks like a tank and on paper matches the gun power but it most definitely is not a tank and things will end very badly very quickly if you ever try to use it as a tank. You have the gun but that’s it, the rest of the balanced platform, developed over decades of battle experience is missing so what you end up with is limited and vulnerable. You are much better off deploying a tank or purpose designed armoured car that isn’t compromised through being designed for another role.

Same with the LHD option, you can carry the aircraft but that about it and you will be severely limiting the utility of the F-35B by tying it to an amphib. You lose amphibious capability to accommodate the F-35s and their minimum support requirements while limiting the performance of the F-35’s through not possessing the full spectrum of support capabilities.

In particular if you are talking about building a third LHD to serve as a carrier a much better option would be a purpose designed carrier. Perhaps a little small and too limited, but it could be argued that something akin to the RTNs HTMS Chakri Naruebet would be a better option if combined with the purchase of a Bay or similar to fill the sealift requirement.

While not ideal a small purpose designed carrier (CVS?) carrying a single sqn each of F-35s, ASW helos and an AEW and a CSAR detachment, would likely be a better and more versatile investment. Design it for fleet speeds, i.e. 18 kt cruise speed / 27kt + max sustained, and endurance 6000Nm +. Incorporate the same combat system as the ANZAC replacements as well as CEC and a decent self defence capability.

There will still only be a half dozen F-35 in peace time and a dozen as required, the big advantage would be the AEW, ASW and CSAR helos added to any task group this ship is assigned to.

Logistics, easy form something akin to the RFA to save costs while tripling the number of fat ships using conversions along the lines of Sirius, perhaps including the sealift ship as well. Maybe look at incorporating operation and support of Customs fleet within this organisation too.

How many ASW helos would be sufficient?

Each escort vessel operates ASW helos plus carries its own sonar. That's already a fairly large number of sonars in the water.

Unlike short-legged fighters, could P-3Cs (or P-8s which can be aerial refuelled?), assuming safe air cover, have much better endurance to clear a anti-sub passage ahead of convoys? Considering that enemy subs have far less speed than enemy fighters, wouldn't any sanitised area have longer lasting effect?

 

[Jaimito]

No it isn’t. The electrical generator is inside the ship but the motor that turns the screws is inside the pod. See the attached patent image. Add this to your list of epic fails.

Sorry, but i used this other picture from Schottel web about the twin propeller, and i saw the transmission inside the body pod and inside the propeller, but now i went to the Spanish navy site and found the other which i´ll try to past.

Anyway it is magnetic electrical engine, similar to subs, probably out of all noises the one generated by that magnetic is a secondary one... just looking at the Spanish site they say wrt fixed or controllable pitch propellers, the system is less noisy, and the Spanish navy use alreday pods before the Jc1, and normal pitchs propellers as well, and they have subs that are old but have absolute moder sonars..etc.
Just looking at the amount of mechanical parts that you save from non using pods, its a list, and all make their noise which adds to the total noise and vibration.

And you can change the propeller without changing the magnetic engine, i edited reference in previous message wrt.

 

[Abraham Gubler]

Anyway it is magnetic electrical engine, similar to subs, probably out of all noises the one generated by that magnetic is a secondary one...

This is not what makes the submarines acoustically silent. It is all the isolation and other stuff around the motor. It doesn’t matter if it is mechanical or electrical a big spinning thing will make a lot of noise. Now if you just stick said spinning thing in the water that noise will be transferred and radiated. I have broken my cardinal rule of not responding to Jaimito’s barrage of nonsensical posts so will leave this discussion point now and not respond any further.