hon@hans.scs.carleton.ca (Edmund Hon) (03/31/91)
From: hon@hans.scs.carleton.ca (Edmund Hon) While we are on the subject of submarines, does anyone know what is the purpose of a mysterious "pod" on top of the tail fin of some of the newer class of USSR SSNs? These classes includes: Akula, Sierra, and Victor III. I've heard of 3 different explainations: a housing pod for towed array sonar, a decoy, or a propulsion device. Also, does anyone know why there were only one boat of the Papa and the Mike class? (Well, the Mike was sunk, so there are none now.) (source: Jane's Warsaw Pact warships handbook. 1986)
ruedi@dtoa1.dt.navy.mil (David Ruedi) (04/01/91)
From: ruedi@dtoa1.dt.navy.mil (David Ruedi)
I recently had a chance to look at an UNCLASSIFIED photo of the
Soviet equivalent to a piping tab for a Victor III. It showed a cut
away view of the boat. The pod in the phot was definitely not a MHD
(or any other) propulsor. It looked like it contained a reel and the
machinery necessary to deploy/recover whatever was on the reel. In
my (not necessarily the Navy, Dod, or US Government's) opinion the reel
holds a towed array, I didn't see any evidence of a buoy.
To the best of my knowledge, the Papa and Mike were one of a kinds
because they were R&D technology demonstrators. Some of the technology
worked, some didn't.
LT David H. Ruedi, USNswilliam@oasys.dt.navy.mil (Steve Williams) (04/01/91)
From: swilliam@oasys.dt.navy.mil (Steve Williams) > ... does anyone know what is the purpose of a mysterious "pod" on > top of the tail fin of some of the newer class of USSR SSNs? Jane's Fighting Ships (1986-85 & 1990-91) doesn't explain, and I won't speculate here. >Also, does anyone know why there were only one boat of the Papa and the >Mike class? "Papa" was apparently a development of the "Charlie" class submarines. The fin is of a much more angular shaped than the "Charlie" classes with a higher casing, a more rounded bow and with the missile tubes having square covers. Built at Severodvinsk. Source: Jane's Fighting Ships 1985-86 Steve Williams
ab3o+@andrew.cmu.edu (Allan Bourdius) (04/01/91)
From: Allan Bourdius <ab3o+@andrew.cmu.edu> >While we are on the subject of submarines, does anyone know what is the >purpose of a mysterious "pod" on top of the tail fin of some of the newer >class of USSR SSNs? These classes includes: Akula, Sierra, and Victor III. I think that the generally accepted explanation is that it's a towed-array housing. >Also, does anyone know why there were only one boat of the Papa and the >Mike class? (Well, the Mike was sunk, so there are none now.) The Soviets built two new classes of SSNs as a test (Akula, Mike) to find out which one was the best design, kind of like the current YF-22/YF-23 competition in our defense industry. One (Mike) was found to be inferior, so no more of that class was built (that's my guess, anyway). The Papa is a cruise missile boat (right?) so perhaps the first sub had design or construction problems or had an accident after completion and the design has fallen out of favor. -- Allan Bourdius ab3o+@andrew.cmu.edu
arthur@Eng.Sun.COM (Arthur Leung) (04/03/91)
From: arthur@Eng.Sun.COM (Arthur Leung) ruedi@dtoa1.dt.navy.mil (David Ruedi) writes: > I recently had a chance to look at an UNCLASSIFIED photo of the >Soviet equivalent to a piping tab for a Victor III. [...] >In my (not necessarily the Navy, Dod, or US Government's) opinion the reel >holds a towed array, I didn't see any evidence of a buoy. if this is the pod at the top of the fin seen on the stern of surfaced soviet submarines, i believe the volume is too small to house your average towed array. a towed array sonar is pretty large in diameter. won't get much of a length in that small space. the towed array housing on Los Angeles class boats looks to be about 1' tube running a good portion of the length of the boat. might this soviet pod be used as a housing and reel for VLF antenna? it would fit better. -- arthur
hon@scs.carleton.ca (Edmund Hon) (04/03/91)
[Reformatted to avoid excessive indentation. --CDR] From: hon@scs.carleton.ca (Edmund Hon) In article <1991Apr3.024755.24304@amd.com> arthur@Eng.Sun.COM (Arthur Leung) writes: >a good portion of the length of the boat. might this soviet pod >be used as a housing and reel for VLF antenna? it would fit better. But why would they want to trail the antenna at the tail when you can do it nicely from the conning tower? Why aren't the other classes do the same? It seems to much of a coincidence for me that only the latest SSN's (not SSGN's i.e., Oscar, Charlie, etc.) have such a pot. Let's look at some of the possible answer to this pot, and the possible reasons against the explainations: i) Towed Array Sonar- Volume too small to house an average length TAS (how long is a TAS anyway), as stated by Arthur Leung. ii) A Decoy (Nixie) - Unless it is a "one-use" disposable one. I can't think of anyway where the sub can detach the pod, trail it behind the sub with a cable, then retrieve it onto the top of the fin. Seems like a pretty tricky operation. (Note: maybe the decoy is INSIDE the pod, then this becomes a very plausible explaination. David Ruedi did say in an earlier post that there are reeling mechanisms in the pod when he saw the cut- away of the Victor III.) iii) A Propulsion device - Too small. iv) A sonar (not a TAS) - Does the size of a sonar (in general) deter- mines the frequency which the sonar can operate? To me it seems that small size => short wavelength => high frequency. If the pod is a sonar, then it must be a high frequency one, which will not be very use- ful when you consider that most of the newer, better sonars utilizes the low frequency approach. Any comments? -- Edmund Hon hon@scs.carleton.ca
tek@CS.UCLA.EDU (Ted Kim) (04/04/91)
From: tek@CS.UCLA.EDU (Ted Kim) arthur@Eng.Sun.COM (Arthur Leung) writes: > If this is the pod at the top of the fin seen on the stern of > surfaced Soviet submarines, I believe the volume is too small to > house your average towed array. A towed array sonar is pretty large > in diameter. It won't get much of a length in that small space. The > towed array housing on Los Angeles class boats looks to be about 1' > tube running a good portion of the length of the boat. Might this > Soviet pod be used as a housing and reel for VLF antenna? It would > fit better. In the "Soviet Navy" column of April 1991 USNI Proceedings, Norman Polomar and LtCmdr Jurrien Noot (Royal Netherlands Navy) mention the tear-drop shaped pod on the Victor III (which is about 29.5 feet long and almost 8 feet at its widest point). Their opinion is that it is most likely a housing for a THIN-LINE towed array sonar. They mention a variety of alternative possibilities: towed communications cable, torpedo decoy system, auxiliary high-speed burst propulsion, auxiliary low-speed creep propulsion. They believe any theories about MHD or EMT auxiliary propulsion systems are not likely because of the high power consumption necessary and because there is no opening on the front of the pod for water intake. Also, they note the high position makes it vulnerable to ice damage. -- Ted Kim Internet: tek@penzance.cs.ucla.edu UCLA Computer Science Department UUCP: ...!{uunet|ucbvax}!cs.ucla.edu!tek 3804C Boelter Hall Phone: (213)206-8696 Los Angeles, CA 90024 FAX: (213)825-2273
norton@manta.nosc.mil (Scott Norton) (04/04/91)
From: norton@manta.nosc.mil (Scott Norton) I always thought it was a mail bouy! :-) :-)
swilliam@oasys.dt.navy.mil (Steve Williams) (04/04/91)
From: swilliam@oasys.dt.navy.mil (Steve Williams) >> If this is the pod at the top of the fin seen on the stern of >> surfaced Soviet submarines, I believe the volume is too small to >> house your average towed array. "The notable feature of the AKULA class is a large streamlined pod on top of the vertical tail fin. The official judgement is that it probably contains a towed sonar array. Others have speculated that a new type of auxiliary propulsion system, based on magnetohydrodynamics (MHD), is involved." Source: SOVIET SUBMARINES: Designs, Development and Tactics by Jan Breemer Jane's Information Group Published in United Kingdom by Jane's Defense Data, a principal activity of Jane's Information Group Limited 1989