071 LPD thread

[Jeff Head]

re: PLAN Type 071 LPD & its Landing Craft

Something like that was done with the Australian Kanimbla class.View attachment 8579

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Many ships, including many in use today, use cranes to lift up their smaller landing craft.

The LASH system was much more complex and involved much heavier machinary becuase the barges were much heavier.

A fully laden LCAC would be heavy compared to most of the smaller landing craft like that shown in the picture with the Australian vessel. This would be particularly true if you wanted to use the system to lift the LCAC sized craft, and then position them in an auxiallary storage area that could be accessed by an LPD's vehicle decks.

Anyhow, that was what I was trying to explain earlier with the LASH discussion.

 

[drunkmunky]

Re: PLAN Aircraft Carrier programme..News & Views

how the hell does that well deck seal?

Do they just constantly use pumps to vacate the water in the bay?

Sorry, I'm talking about the 71

 

[drunkmunky]

Re: PLAN Aircraft Carrier programme..News & Views

Can someone answer my question about the type 71 rather than talking about geopolitical positioning?

Mentioning OT, doesn't mean it's ok. hate to step on your hard on's gents.

 

[Blitzo]

Re: PLAN Aircraft Carrier programme..News & Views

Can someone answer my question about the type 71 rather than talking about geopolitical positioning?

Mentioning OT, doesn't mean it's ok. hate to step on your hard on's gents.

... I assume the well deck of 071 works similarly to most well decks.

The water is probably pumped out and ballast tanks emptied when the well deck isn't in use, which both makes the ship rise out of water enough so the water won't enter the well deck, and also so it'll empty the well deck of present water.
The well deck is shut and the ship has a lower draft in the water when they well deck isn't in use.

 

[Engineer]

Re: PLAN Aircraft Carrier programme..News & Views

how the hell does that well deck seal?

Do they just constantly use pumps to vacate the water in the bay?

Sorry, I'm talking about the 71

There are ballast tanks under the ship that can control the pitching angle of the ship. When the bay needs to be flooded, water is pumped into ballast tanks near the stern. The rear of the ship gets pushed down, and water from outside floods into the bay from the aft end. To vacate the bay of water, water is pumped out of the ballast tank. The rear of the ship lightens up, and water drains from the bay through the aft end.

 

[plawolf]

Re: PLAN Aircraft Carrier programme..News & Views

There are ballast tanks under the ship that can control the pitching angle of the ship. When the bay needs to be flooded, water is pumped into ballast tanks near the stern. The rear of the ship gets pushed down, and water from outside floods into the bay from the aft end. To vacate the bay of water, water is pumped out of the ballast tank. The rear of the ship lightens up, and water drains from the bay through the aft end.

I don't think the ballast tanks just tip the back end of the 071 down. The entire waterline is raised and the well deck is flooded evenly.

 

[Quickie]

Re: PLAN Aircraft Carrier programme..News & Views

To simplify things, I think the entire well deck acts as the ballast tanks itself. The well deck will have to extend through the centre of gravity of the ship, so that when it fills up with water or starts emptying it, the ship will has zero or minimum tilting.

 

[drunkmunky]

Re: PLAN Aircraft Carrier programme..News & Views

But that door and the way that it operates with a hinged bottom is impossible to seal.

During high seas, pumps would still need to be active to evacuate the water out of the deck?

Talking about 10 metre + waves during typhoon like conditions.

 

[plawolf]

Re: PLAN Aircraft Carrier programme..News & Views

But that door and the way that it operates with a hinged bottom is impossible to seal.

During high seas, pumps would still need to be active to evacuate the water out of the deck?

Talking about 10 metre + waves during typhoon like conditions.

I don't see how the door would be impossible to seal up.

 

[Jeff Head]

re: PLAN Type 071 LPD & its Landing Craft

A question was raised on another thread about the well deck doors on large amphibious assault vessel. One poster indicated that such doors would be impossible to keep water tight in heavy seas.

Of course, the water tight integrity of modern well decks has been ensured. Earlier LSDs had what was called a weather deck, which was open to the weather and was designed to allow water to catch there and be drained off, and to allow vessels to sail right in. There well deck door was not as watertight. The Ashland Class LSDs (the first US LSDs) were an example of this. Their weather/welldeck initially was open for almost its entire length, although later they were modernized and a helicopter landing deck for was built over most of it.

However, new class LSDs, LPDs, LHDs, LHAs etc. are designed for water-tight integrity.

Here are a couple of pictures where the hydraulic operating (opening/closing) mechanisms and the seals are clearly visible. Those doors are raised against their seals and water tight integrity is accomplished and then maintained with those actuators.

French Ouragan Class LPD

US Wasp Class LPD
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