Great video. Regarding the propulsors, I think that the principal advantage of the pumpjets over propellers is that they are able to achieve much higher speeds without cavitation occurring on any of the blades. This allows them to achieve a much higher 'tactically silent' speed, since cavitation (the creation of voids in the water) tends to dominate most other sources of noise once it starts occurring. The shroud of the pump jet actually slows down the water column and raises its pressure before it comes into contact with the rotors. Such a shroud is also called a 'decelerating duct' for this reason. The trade-off is that at very low speeds, the pump-jets are less propulsively efficient, since slowing down water that's already moving slowly means that some part of the water turns around moves in the opposite direction. This is called flow-separation. I actually don't think that at low speeds pump jets are actually any quieter than open propellers, at least while the propellers can operate without causing any cavitation. In fact they might be ever-so-slightly louder, because of the greatly increased turbulence of the flows inside the shroud. But the pump-jets would be vastly quieter at any speeds where a propeller would cavitate. Since conventional submarines can't sustain such speeds for any useful period of time anyway, they choose propellers consistently over pump jets.
I was very fortunate with service on DDG (Charles F Adams) class warships when serving in the Royal Australian Navy. 4 x 1250psi Foster Wheeler D Type boilers and 2 x General Electric 3 stage steam turbines. The system was a superheated steam system. As you pointed out a steam system is very complex with a lot of pipework and auxiliary systems, and steam recovery systems. Having said that, steam is the most amazing propulsion system yielding fantastic efficiencies.
YOu;re right, supeheated steam systems are indeed very efficient, but the secondary loop of nuclear submarines operate at lower temperatures using saturated steam. THis creates other problems related to wear as wel as lower power. To supeheat the steam would require the primary loop o be kept at enomous pressure., so early RN SSns used the saems designs adn WW! waships !
I really need to sort that out! I had four parts but realised there were errors and meant to redo them. I never expected this presentation to be so popular! I'll try and correct the errors and get these videos up again in the next month!
15:04 in September 2021 Australia announced that they will build (with US/UK help) and operate nuclear powered attack submarines. From the descriptions, they might be using the US virginia-class attack submarine design.
HMS Trafalgar's screw is - or was - on display at Devonport since decommissioning; it's a 7 bladed skewback screw, that's relatively aggressive in its skew and sharp tips.
Am sure we all appreciate you may be limited on the amount of detail you can provide. However the science of fluid dynamics is in the public domain and I'm already on several watch-lists so not overly worried about mentioning a few things. 🐬 Like ducted propellers are more efficient at lower rpm & significantly quieter plus surface vessels have been openly enjoying the advantages of variable pitch propellers for decades.
What you say about props is true. However, propellers with 2, 4, 6, or 8 blades can resonantly vibrate like a bell. Whereas propellers with 3, 5, 7, or 11 blades do not do this. Skewed blades also minimize self vibration. Larger blades exert less force per surface area which reduces cavitation, and they reduce turbulence. The cowled propellers have greater directional precision and do not side slip in a turn. This gives greater precision in a turn as well as in cross currents.
Thanks for that, I appreciate it. I totally forgot about the surface area! Judging by your icon, you also know a lot about nuclear reactors? I am currently trying to make part 2 but its hard without exposing classified information, so I think its going to have to be based on civilian reactors and things like the USS Savannah. Hopefully I'll get it out on the weekend.
India has an operational nuclear ballistic missile submarine (SSBN) INS Arihant which is the lead ship of Arihant class submarines. Another submarine of this class INS Arighat is undergoing sea trials currently. These submarines were built in India and weren't leased from Russia like INS Chakra which is a Russian Akula class submarine. Beside this, India is going to start the Project to build Nuclear Attack Submarines (SSN) very soon. Thank you!
Well, considering the fact no one has used a nuclear weapon for nearly 80 years, I think it's more fair to say these subs have been built as a deterrent and not to kill people. The MAD doctrine has been pretty damn effective, arguably, for a very long time.
Hi, I was attempting to run part three of the four parts series - as it is one of my favourites. I couldn't find it. I only found part 1 (this one): What happended to the other parts. Fortunately I have it on my external HD - unfortunatey the HD is at home, and not at the airport where I spend friday afteroon. As a backup I rund part 1
@@drawingboard82 Thanks for a fast reply - I guess the missing parts will be back in the not too distant future. That said, know that a part with a few minor errors outshine no parts!
You stated that all missile submarines were nuclear and it was a requirement as such. However recently south Korea has developed a non-nuclear missile submarine. While it obviously can't operate in the worldwide oceans, it can serve as a mobile launching platform in its territorial waters and nearby waters. This is superior than a fixed land based missile system.
The Soviet Union built some sodium cooled reactors in submarines, but the reactivity of the sodium with water creates numerous safety issues in a naval vessel.
@@Griz1231 that had to a good idea molded sodium chloride is not fun in water. But running high pressure reactors 15 times atmosphere not a good choice either
Thank you so much for this video! It was very helpful and informative. ❤️🔥🙏🦾 But am I really the only one who realizes they are using a Tesla disc stack pump for zero cavitation and windage on the “screw”?! 🤭🦾🤓👨🔬 Lol what a convenient word “screw” and way to get everyone’s mind to immediate think complex geometry screw pattern for no cavitation when in fact it’s the exact opposite. Classic obfuscation. Flat discs with no tips that cause acoustic or EM oscillations and variations. Also using the Tesla turbine for the steam turbine means there would be no need for a reversing gear as the steam is just sent into a different nozzle that spins the discs the opposite way.
Also using the Tesla turbine for the steam turbine means there would be no need for a reversing gear as the steam is just sent into a different nozzle that spins the discs the opposite way.
Great Lesson. Thanks for covering this in a manner that can be consumed by the majority. Thanks!
Thank you for this great video. I have just watched the first 15 minutes and will come back for more when I'm off work.
You're welcome. I hope you enjoy it.
Very much enjoyed, thanks for posting this! Hoping that part 2 is made available again soon!
Great video. Regarding the propulsors, I think that the principal advantage of the pumpjets over propellers is that they are able to achieve much higher speeds without cavitation occurring on any of the blades. This allows them to achieve a much higher 'tactically silent' speed, since cavitation (the creation of voids in the water) tends to dominate most other sources of noise once it starts occurring. The shroud of the pump jet actually slows down the water column and raises its pressure before it comes into contact with the rotors. Such a shroud is also called a 'decelerating duct' for this reason. The trade-off is that at very low speeds, the pump-jets are less propulsively efficient, since slowing down water that's already moving slowly means that some part of the water turns around moves in the opposite direction. This is called flow-separation. I actually don't think that at low speeds pump jets are actually any quieter than open propellers, at least while the propellers can operate without causing any cavitation. In fact they might be ever-so-slightly louder, because of the greatly increased turbulence of the flows inside the shroud. But the pump-jets would be vastly quieter at any speeds where a propeller would cavitate. Since conventional submarines can't sustain such speeds for any useful period of time anyway, they choose propellers consistently over pump jets.
I was very fortunate with service on DDG (Charles F Adams) class warships when serving in the Royal Australian Navy. 4 x 1250psi Foster Wheeler D Type boilers and 2 x General Electric 3 stage steam turbines. The system was a superheated steam system. As you pointed out a steam system is very complex with a lot of pipework and auxiliary systems, and steam recovery systems. Having said that, steam is the most amazing propulsion system yielding fantastic efficiencies.
YOu;re right, supeheated steam systems are indeed very efficient, but the secondary loop of nuclear submarines operate at lower temperatures using saturated steam. THis creates other problems related to wear as wel as lower power. To supeheat the steam would require the primary loop o be kept at enomous pressure., so early RN SSns used the saems designs adn WW! waships !
Here to beg for part 2.
I really need to sort that out! I had four parts but realised there were errors and meant to redo them. I never expected this presentation to be so popular! I'll try and correct the errors and get these videos up again in the next month!
Same!
15:04 in September 2021 Australia announced that they will build (with US/UK help) and operate nuclear powered attack submarines. From the descriptions, they might be using the US virginia-class attack submarine design.
MORE!!! PLEASE MORE!!!
HMS Trafalgar's screw is - or was - on display at Devonport since decommissioning; it's a 7 bladed skewback screw, that's relatively aggressive in its skew and sharp tips.
Why is part 2 private? I would love to rewatch it
Can you put a link to part 2 in the comments? I enjoyed your casual yet informative stroll through the concepts.
ua-cam.com/video/S5ed0bf0SvQ/v-deo.html
@@drawingboard82 . it looks like this link is private. Can you make it open for everyone again?
Yes, I’d love to re-watch part 2 again, I saw it months ago, but it looks private now.
Can u please make part 2 public
@@drawingboard82 are you allowed to make part 2 public again? Very interesting stuff
Am sure we all appreciate you may be limited on the amount of detail you can provide. However the science of fluid dynamics is in the public domain and I'm already on several watch-lists so not overly worried about mentioning a few things. 🐬 Like ducted propellers are more efficient at lower rpm & significantly quieter plus surface vessels have been openly enjoying the advantages of variable pitch propellers for decades.
Thanks. Where is the Part 2 ?
What you say about props is true. However, propellers with 2, 4, 6, or 8 blades can resonantly vibrate like a bell. Whereas propellers with 3, 5, 7, or 11 blades do not do this. Skewed blades also minimize self vibration. Larger blades exert less force per surface area which reduces cavitation, and they reduce turbulence.
The cowled propellers have greater directional precision and do not side slip in a turn. This gives greater precision in a turn as well as in cross currents.
Thanks for that, I appreciate it. I totally forgot about the surface area! Judging by your icon, you also know a lot about nuclear reactors? I am currently trying to make part 2 but its hard without exposing classified information, so I think its going to have to be based on civilian reactors and things like the USS Savannah. Hopefully I'll get it out on the weekend.
India has an operational nuclear ballistic missile submarine (SSBN) INS Arihant which is the lead ship of Arihant class submarines. Another submarine of this class INS Arighat is undergoing sea trials currently. These submarines were built in India and weren't leased from Russia like INS Chakra which is a Russian Akula class submarine. Beside this, India is going to start the Project to build Nuclear Attack Submarines (SSN) very soon. Thank you!
Thanks for the information! You're welcome.
Thanks for your revert! I forgot to mention the video is absolutely amazing! Awesome content and presentation. Great work!!
@@sauravghosh3534 I'm glad you enjoyed it!
Awesome presentation.
Glad you like it. I have more in the pipeline but struggling with motivation at the moment!
Well, considering the fact no one has used a nuclear weapon for nearly 80 years, I think it's more fair to say these subs have been built as a deterrent and not to kill people. The MAD doctrine has been pretty damn effective, arguably, for a very long time.
Hi, I was attempting to run part three of the four parts series - as it is one of my favourites. I couldn't find it. I only found part 1 (this one): What happended to the other parts.
Fortunately I have it on my external HD - unfortunatey the HD is at home, and not at the airport where I spend friday afteroon. As a backup I rund part 1
Sorry, I have taken them down for now. They had a few minor errors and I want to remake them! I really appreciate your feedback though.
@@drawingboard82 Thanks for a fast reply - I guess the missing parts will be back in the not too distant future.
That said, know that a part with a few minor errors outshine no parts!
Excellent video! Would love to see part two but it is labeled as private.
Probably Confidential Atomic, need SC Clearance for that lol or worse like DV for SECRET / TOP SECRET
Nerwin was a peaceful little sub when she existed, not a weapon on her.
You stated that all missile submarines were nuclear and it was a requirement as such. However recently south Korea has developed a non-nuclear missile submarine. While it obviously can't operate in the worldwide oceans, it can serve as a mobile launching platform in its territorial waters and nearby waters. This is superior than a fixed land based missile system.
India operates its own Nuclear powered submarine of the Arihant class which is currently operational from the last 8 years now
Id totally forgotten that. You're right, sorry.
I wonder if they have tried molten salt reactors. You do not have to create pressure in the core.
The Soviet Union built some sodium cooled reactors in submarines, but the reactivity of the sodium with water creates numerous safety issues in a naval vessel.
@@Griz1231 that had to a good idea molded sodium chloride is not fun in water. But running high pressure reactors 15 times atmosphere not a good choice either
@@joem80003 lol
Like a piped version of a toroidal prop!
In a cone shape, but without the cone shape would be less detectable! More surface area, less bubbles!
Four of the Ohio class were converted into SSGNs with each trident being replaced with a cluster of 7 tomahawk cruise missiles.
Billions and billons and billions and billions per unit? Hmmm
Real anti boat aren’t you. Turning off.
Can we please stop saying water is incompressible and start saying water is nearly incompressible
Thank you so much for this video! It was very helpful and informative. ❤️🔥🙏🦾
But am I really the only one who realizes they are using a Tesla disc stack pump for zero cavitation and windage on the “screw”?! 🤭🦾🤓👨🔬
Lol what a convenient word “screw” and way to get everyone’s mind to immediate think complex geometry screw pattern for no cavitation when in fact it’s the exact opposite.
Classic obfuscation.
Flat discs with no tips that cause acoustic or EM oscillations and variations.
Also using the Tesla turbine for the steam turbine means there would be no need for a reversing gear as the steam is just sent into a different nozzle that spins the discs the opposite way.
Also using the Tesla turbine for the steam turbine means there would be no need for a reversing gear as the steam is just sent into a different nozzle that spins the discs the opposite way.