A hypothetical carrier buy for the RAN?

[Jaimito]

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.

For God´s shake.

The noise is caused by moving parts, or shocking metalic parts, also the vibrations, they are interelated, vibrations from cavitation is other, but the magnetic engines don´t have moving parts! Or have many less moving parts or pure metalic shocks, you might not even need to hide it. And anyway all the rest of moving components that you save using pods, it is a long chain, are you going to isolate it so well easily?

I try to put doubts on your "assumptions".

 

[gf0012-aust]

For God´s shake.

The noise is caused by moving parts, or shocking metalic parts, also the vibrations, they are interelated, vibrations from cavitation is other, but the magnetic engines don´t have moving parts! Or have many less moving parts or pure metalic shocks, you might not even need to hide it. And anyway all the rest of moving components that you save using pods, it is a long chain, are you going to isolate it so well easily?

I try to put doubts on your "assumptions".

Can you knock it off?

Having worked on subs for 3 different class types, I can tell you first hand that abes comments about acoustic detection issues are correct

STOP telling people who have a functional knowledge of these things how they work when its apparent that you don't.

Your understanding of the dynamics of acoustics in subs is wrong - all subs emit, all subs are in effect managed transducers, and if its doing more than 5 knots then whatever machinery that is not managed will be contributing to its noise footprint.

2nd warning. Next will be final and you will be banned.

 

[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.

Can you tell me where is that picture from?

 

[alexsa]

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?

Sorry that is only for tugs, for commercial pos the motor is in the pod.

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.

You can conduct prop repairs underwater on commercial ships now, this is not a biggy. Even the Oberons could have a prop replaced while alongside....... I fail to see the advantage the pod offers in this regards. The pods are great commercial advance but have had teething issues

I paste:

"Advantages
•Substantially higher efficiency than Z drives with a single propeller.

Err so ........ Where have you seen a Z drive in either a comercial ship or a war ship

•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 .

I think you are talking aobut tug boats here...... not large vessel applications.

•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 .

No arguement ..... but bearing issues ofter mean complete removal of the pod. This is significantly more work that a shaft line issue.

•Particularly suitable for installations permitting only limited propeller diameters (restricted draught or required tip clearance) ".

True for tugs but on many large podded ships the pod and props are still below the hull line. for a large commercial shilp neither the prop pf the rudder generall protude below the keel line.

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

The LHD is based on commercial rules modified to military requirements. Be careful about deriding commercial rules as some of these are ahead of the technolgy curve (ignoring the acousitc issue which they most certainly are not) hence their use by the military. I doubt many navla design organisations ahve formualted rules for pods.

 

[alexsa]

Can you tell me where is that picture from?

Please do some research........... Look up rolls Royce Mermaid but you need to be careful to ensure the pod your looking at is not for a tug boat.

On another issue, your comments with regard to cavitation are rubbish. Caviatation problems are casued by a range of issues such as:

• hull design
• prop design ( a real biggy in this isuses)
• and the impact both of these have on operating envelope.

Wheyher or not the prop is driven by an elctric motor may be completely irrelevant if the prop is not suited to purpose................................. this is even true in a merchant ship, however, considerations with respect of caviataion relate to normal operating speed, not a range of operations. This is not for silence (we leave that to the military) but because caviation casued efficiency losses (more fuel - more cost) and damage to the propeller (again more cost).

 

[Volkodav]

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?

I imagine a deployed ASW Helo sqn would have 6 to 9 airframes.

Unless the OCVs are designed to operate Seahawk / NH-90, once the FFGs (with their twin hangers vs the singles on the ANZACs and AWDS) retire over the coming decade there will be far fewer helo spots at sea. A carrier with its hanger and maintenance facilities could be used to extend the endurance of helo detachments onboard our surface combatants.

Remember we are only ordering 8 P-8s so would that be sufficient to sanitise a convoy route as well as everything else they will need to do?

 

[Aussie Digger]

I imagine a deployed ASW Helo sqn would have 6 to 9 airframes.

Unless the OCVs are designed to operate Seahawk / NH-90, once the FFGs (with their twin hangers vs the singles on the ANZACs and AWDS) retire over the coming decade there will be far fewer helo spots at sea. A carrier with its hanger and maintenance facilities could be used to extend the endurance of helo detachments onboard our surface combatants.

Remember we are only ordering 8 P-8s so would that be sufficient to sanitise a convoy route as well as everything else they will need to do?

AIR-9000 Phase 8 (Future Naval Aviation Combat System) is scoped to acquire up to 24x ASW helos, with the intention of be capable of operating 8 aircraft at sea at any particular time. With 11 major surface combatants, you'd have to think that there will rarely be more than 8 at sea at any one particular time, so the scoping work seems pretty well thought out, though VTOL UAV's are reportedly in RAN's sights within future years, so this may upset the balance somewhat. Still there is no guarantee that the "Future Frigate" won't have 2 spots available...

Clearly surge deployments will be possible in future years and if you include the LHD's into your planning there will be significantly more helo spots at sea than we have now.

Even with the 4x FFG's only being replaced with 3x AWD's, the overall spots will still dramatically increase and I imagine the LHD's will carry at least one FNACS helo to sea on every deployment and more if required due to the operational environment...

Defence Capability Plan 2009 - Public Version - December 2010 Update

 

[Jaimito]

Please do some research........... Look up rolls Royce Mermaid but you need to be careful to ensure the pod your looking at is not for a tug boat.

On another issue, your comments with regard to cavitation are rubbish. Caviatation problems are casued by a range of issues such as:

• hull design
• prop design ( a real biggy in this isuses)
• and the impact both of these have on operating envelope.

Wheyher or not the prop is driven by an elctric motor may be completely irrelevant if the prop is not suited to purpose................................. this is even true in a merchant ship, however, considerations with respect of caviataion relate to normal operating speed, not a range of operations. This is not for silence (we leave that to the military) but because caviation casued efficiency losses (more fuel - more cost) and damage to the propeller (again more cost).

Not tug boat, the pod refered in the "advantages" pasted before is twin propeller, and it is 6 mwatts for 1 propeller per pod as a max reference for 1 propeller per pod by Schottel, and they present the twin propeller as i pasted, which is associated theoretically with 11 mwatts for the Lhd per pod.

Lhd of 27000 t., then 6 mwatts half of that, for example, 13000t. ships, so probably not tug boat. But those pods (twin or not) are already in 20000 t. commercial ships.

Wrt my comments on cavitation: it seems, i´ve read, the problems in the Charles de Gaulle carrier, is that cavitation problems are producing vibrations that the structure of the ship is not supporting. 42000 t., 2x150 mwtts reactors, 2 shafts. Imagine the workload for each propeller..

 

[alexsa]

Not tug boat, the pod refered in the "advantages" pasted before is twin propeller, and it is 6 mwatts for 1 propeller per pod as a max reference for 1 propeller per pod by Schottel, and they present the twin propeller as i pasted, which is associated theoretically with 11 mwatts for the Lhd per pod.

Lhd of 27000 t., then 6 mwatts half of that, for example, 13000t. ships, so probably not tug boat. But those pods (twin or not) are already in 20000 t. commercial ships.

Wrt my comments on cavitation: it seems, i´ve read, the problems in the Charles de Gaulle carrier, is that cavitation problems are producing vibrations that the structure of the ship is not supporting. 42000 t., 2x150 mwtts reactors, 2 shafts. Imagine the workload for each propeller..

This is a Z drive. Z drives are not used in pods for large vessels such as the LHD.

With the CdG you have just made my point, hull design and prop. It does not hold that the more props you have the less caviation. if the design is wrong thye will cavitate...... just more of them will do it.

As I said.... do some reasearch. Pods are in much larger vessels than 20000 tonne (Queen Mary II) but this does not mean the desing is quieter and more effecient for all applications whihc you are trying to claim.

 

[Volkodav]

AIR-9000 Phase 8 (Future Naval Aviation Combat System) is scoped to acquire up to 24x ASW helos, with the intention of be capable of operating 8 aircraft at sea at any particular time. With 11 major surface combatants, you'd have to think that there will rarely be more than 8 at sea at any one particular time, so the scoping work seems pretty well thought out, though VTOL UAV's are reportedly in RAN's sights within future years, so this may upset the balance somewhat. Still there is no guarantee that the "Future Frigate" won't have 2 spots available...

Clearly surge deployments will be possible in future years and if you include the LHD's into your planning there will be significantly more helo spots at sea than we have now.

Even with the 4x FFG's only being replaced with 3x AWD's, the overall spots will still dramatically increase and I imagine the LHD's will carry at least one FNACS helo to sea on every deployment and more if required due to the operational environment...

Defence Capability Plan 2009 - Public Version - December 2010 Update

Fair call but what about the torpedoes and ASMs when deployed on the LHDs? Add to that the increased tail if the RAN (as looks likely) get Romeo over NH-90?

Will the OCVs require a third helo type, something smaller?

I suppose the other arguement is a larger fleet of helicopters would not be amiss either.

 

[Kirkzzy]

Wow, a lot has happened in the past week.. I was going to post a reply sooner but had to evac cause of the flood, then was without power for a few days followed by internet................. ANYWAY.

I am no expert but what about the second option of my post that was on p43 I think?

The QE2 carrier would be great, and as a cost saving measure we could arm it with our SHs with the possibility of getting more or even put some legacy hornets on it since we are in peace time. This capability would be able to give us a FOB to any future "surprise" attack, and when the carrier is under maintenance we can station the aircraft at Christmas island or something. We will also be able to back up our LHDs in amphibious assault operations like people above have been trying to argue need CAS.

Just my 2 cents, is it it possible?

 

[Sea Toby]

We will also be able to back up our LHDs in amphibious assault operations like people above have been trying to argue need CAS.

What is wrong with using the Australian Army's Tiger ARHs off the LHDs for close air support? Please explain why the LHDs require fighter jets to support the troops with close air support when Tigers are available? Maybe some should research the Tigers capabilities...

 

[SASWanabe]

What is wrong with using the Australian Army's Tiger ARHs off the LHDs for close air support? Please explain why the LHDs require fighter jets to support the troops with close air support when Tigers are available? Maybe some should research the Tigers capabilities...

im honestly not even sure if the tigers are marinised... i still think we shoulda gone for AH-1Z Viper for the LHDs

 

[aussienscale]

What is wrong with using the Australian Army's Tiger ARHs off the LHDs for close air support? Please explain why the LHDs require fighter jets to support the troops with close air support when Tigers are available? Maybe some should research the Tigers capabilities...

And where exactly are the Australian Tigers up to with their certifications ?
How long do we have to wait ?

 

[StingrayOZ]

they arent ioc (AFAIK). they arent specifically marinised.They should be near IOC, but there have been a few set backs and delays etc.

France has opearted one off a mistral for training exercises I believe. Pushed come to shove if they were operational they could be operated off the LHD but would require careful watch of wear etc. There was talk of offering a marine kit, folding rotors, engine, etc, france certainly seems keen to operate them from her LHD/carrier. UK operates apaches from her amphibious ships. With hindsight I think we should have got something that would be operational by now.

These issues may well be resolved by the time the first LHD is in IOC. I would imagine the Tiger would fill the CAS gap at least regionally. Anything out of region our partners would provide.

 

[gf0012-aust]

What is wrong with using the Australian Army's Tiger ARHs off the LHDs for close air support?

they will be, thats what part of their certification requires.

 

[gf0012-aust]

And where exactly are the Australian Tigers up to with their certifications ?

not certified for maritime or expeditionary ops yet.

 

[aussienscale]

not certified for maritime or expeditionary ops yet.

Thanks for that GF, although I still personally have a concern for their maritime suitability, but having said that realistically how often will we see them on the LHD's ? So timeline wise are we roughly on track for the certifications along with the LHD's etc ? And where are they at with weapons certifications ? IIRC they were having some troubles there as well ?

Just as a side question, has there been any real interest (other than forum/blog) shown in the Bay Class ?

Thanks

 

[gf0012-aust]

Thanks for that GF, although I still personally have a concern for their maritime suitability, but having said that realistically how often will we see them on the LHD's ?

I would imagine that we'd see a flight or short squadron sent on any expeditionary or recovery mission where displays of or actual need of covering support would be needed. eg, sending in Tigers during ET would have alleviated some tasking pressures. In fact, Tigers, more chooks, C-17's and the LH's are all legacies of post event analysis (lessons learnt) coming out of ET in 99

So timeline wise are we roughly on track for the certifications along with the LHD's etc ? And where are they at with weapons certifications ? IIRC they were having some troubles there as well ?

NFI for one and NC for the other

Just as a side question, has there been any real interest (other than forum/blog) shown in the Bay Class ?

NFI, but I haven't seen any serious chat yet.

 

[weasel1962]

Re:

I am no expert but what about the second option of my post that was on p43 I think?

The QE2 carrier would be great...

If the RAN couldn't even justify a sqn of F-35Bs for the LHDs, how much more can they justify a multi-$b vessel?

The opportunity cost of a QE is easily a couple of sqns of F-35As. I think the RAAF would rather more F-35As than the carrier. There's a lot of competing priorities higher up on the scale for the military $ budget.