Ask anything Thread


Tam

Brigadier
Registered Member
This just popped into my head, so here I come to ask.

Why does many submarine sonar use cylindrical arrays? I find it weird that some of the arrays are actually facing the submarine hull itself. Wouldn't it be more efficient to just make a half-cylinder array so all the sonar waves are sent outwards to detect targets/obstacles?

There are half cylinder arrays too.

Sonar arrays act like active phase arrays, each element has a receiver and transmitter unless it's passive then it's all receivers. The array beam forms and focuses on one hemisphere. If the beam is to be formed, steered and focused at three 'o'clock, you can use the elements from 12 o'clock to 6. But if the beam has to steered past 3' you will notice you will have less elements available for this. So a bow cylindrical or spherical sonar is strongest at the frontal hemisphere from 9' to 3'.

If you sent sound waves simultaneously from all elements in all directions, the sound doesn't get far without being focused and steered into a beam.

You will notice that a half cylinder does not present as much elements to focus and steer a beam to the sides as a full cylinder.
 

charles18

New Member
Registered Member
Question:
Does the PLA-navy have a severe shortage of Underway Replenishment ships?

The US-navy has 31 Replenishment ships:
15 Henry J. Kaiser - oilers
2 John Lewis-class - oilers
14 Lewis and Clark - dry cargo
Each ship weighs about 45,000 tons so this comes out to a total of 1.4 million tons worth of Replenishment ships. The PLA-navy would have to double its production rate of the Type 901 supply ship from 1 ship every two years to 1 ship every year and do so for the next 20 years straight to roughly equal the US navy.

Am I correct or am I looking at this the wrong way?
 

lcloo

Senior Member
Question:
Does the PLA-navy have a severe shortage of Underway Replenishment ships?

The US-navy has 31 Replenishment ships:
15 Henry J. Kaiser - oilers
2 John Lewis-class - oilers
14 Lewis and Clark - dry cargo
Each ship weighs about 45,000 tons so this comes out to a total of 1.4 million tons worth of Replenishment ships. The PLA-navy would have to double its production rate of the Type 901 supply ship from 1 ship every two years to 1 ship every year and do so for the next 20 years straight to roughly equal the US navy.

Am I correct or am I looking at this the wrong way?
US navy has 11 aircraft carriers, and they operate all over the World, tens of thousands of KM from USA. And they have lots of LHA and LPD etc.

China has 2 aircraft carriers (plus one under out-fitting, i.e. 003) operating close to China, They have not gone beyond South China Sea and Western Pacific. In future when PLAN's large capital ships increase in numbers, and also when they extend their operations globally like US Navy, and only then would China build more large supply ships like type 901 in numbers closer to that of US navy, but this will happen in who knows what year would that be?
 

YES

New Member
Registered Member
Question:
Does the PLA-navy have a severe shortage of Underway Replenishment ships?

The US-navy has 31 Replenishment ships:
15 Henry J. Kaiser - oilers
2 John Lewis-class - oilers
14 Lewis and Clark - dry cargo
Each ship weighs about 45,000 tons so this comes out to a total of 1.4 million tons worth of Replenishment ships. The PLA-navy would have to double its production rate of the Type 901 supply ship from 1 ship every two years to 1 ship every year and do so for the next 20 years straight to roughly equal the US navy.

Am I correct or am I looking at this the wrong way?
if they go and say "I'll be running around the globe like US" tomorrow morning, then yeah, but if everyone's calm and still protect merchant ships then their storage is enough for their current regional demand, and the speed is fine for them to slowly take over the US navy globally as their future plans
 

Sinnavuuty

Junior Member
Registered Member
Question:
Does the PLA-navy have a severe shortage of Underway Replenishment ships?

The US-navy has 31 Replenishment ships:
15 Henry J. Kaiser - oilers
2 John Lewis-class - oilers
14 Lewis and Clark - dry cargo
Each ship weighs about 45,000 tons so this comes out to a total of 1.4 million tons worth of Replenishment ships. The PLA-navy would have to double its production rate of the Type 901 supply ship from 1 ship every two years to 1 ship every year and do so for the next 20 years straight to roughly equal the US navy.

Am I correct or am I looking at this the wrong way?
You're looking the wrong way.

Not all are USPACFLT, I would say half or just over half of these ships are. Looking at the simplest way, the number drops to 16 ships with 700 thousand tons.
 

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