February 1, 2016

P-8 anti-submarine warfare (ASW) detection technologies.

Stirring Indian Navy recruitment? and Boeing sales youtube for India P-8Is. 32 seconds in P-8's electro-optical sensor detects a (likely Kilo) submarine's attack? periscope. Sonobuoys then dropped etc. 2:40s one of India's last Harriers fires expensive missiles at dinghies (serious need for Harrier cannon!). I wonder if Pakistan also wants to buy P-8s?

The following are February 1, 2016 comments by Josh on on Submarine Matters article P-8 Poseidons becoming operational and sales success, of January 31, 2016. I have added links and supporting material in […] brackets:

“High altitude has a host of advantages, including:

-  fuel economy,

-  immunity from AAA/MANPADS [Anti-Aircraft Artillery like 14.5 mm ZPU heavy machine guns and small MAN-Portable Air Defence Systems - missiles like Strela-2s]

-  increased airframe life

-  increased transit speed, and,

-  wider sensor field of view/horizon.

About the only drawback is the loss of MAD detection and decreased accuracy of sonobuoy drops.

[Sonobuoy drops] can be addressed by delaying parachute deployment, spin stabilizing the buoys, and using dropsondes to identify wind patterns at lower altitudes.

[On dropsondes see KaZaK Composites Inc’s Low Cost, Precision Aerial Dropsonde Delivery Vehicle response to a US Navy 2006 project or tender? http://www.navysbir.com/06_1/184.htm ]

MAD is used for target localization, not initial detection, so it seems likely the USN has decided this step can be handled by active sound sources, either the multi-static active coherent [MAC] source upgrade for the P-8

[The Multi-Static Active Coherent (MAC) sonobuoy system uses a single noise source sonobuoy and multiple receiver sonobuoys. By using multiple receivers, the MAC system can theoretically cover more volume and provide greater sensitivity since the sound echoes can be correlated over multiple receivers. This requires a great deal of sophisticated analysis software and high degree of operator skill to interpret results. The MAC will hopefully promote P-8 ability to conduct wide area ASW searches.]

 or a traditional AN/SSQ-62 DICASS type buoy.

It could be these systems are NOT being offered to allied nations (particularly India) or that allied nations might not have the resources to upgrade their aircraft in a timely fashion and want to retain MAD as a back up/stop gap. The only major savings of deleting the MAD boom is relatively minor cost and fuel savings.

I'm not aware of diesel fumes being a detection method since [Autolycus on] the Shackletons were taken out of service. I'm not sure the USN ever used the technique.

LIDAR might be viable in sufficiently shallow water but it doesn't appear to be capable of large volume searches. I'm not aware of any underwater search sensor using lasers in service outside of the ALMDS mine detection system, though I know green lasers have been used for mapping shallow water areas of coastline.

Josh [and Pete]


Josh said...

It looks like the P-8 may in fact have some kind of hydrocarbon sensor, though I haven't found a hard source for it yet. See Anonymous's comments in the previous P-8 article. I'm pretty sure the P-3 never did however - most likely because the primary threat would be ocean going Russian nuke boats in the North Atlantic more than D/Es which tended to see more barrier/bastion use closer to the North Fleet's basing area.

Glad something I posted was of interest!


Anonymous said...

The AN/APS-154 Advanced Airborne Sensor can detect masts and periscopes at great distances. AAS brings ISR&T capabilities to the P-8 and allows P-8 to function as a J-Stars for USN. AAS has been going through tests since 2014 (to be completed in 2016).

Josh said...

Quick search during a break from work (you don't need to post the comment, this is just FYI). A hydrocarbon sensor apparently at least was part of the design, though I can't find a recent source mentioning it. I'm still surprised as the areas it would patrol would tend to be awash in diesel fumes and if a boat is snorting, its air intake should be a pretty obvious radar target at longer ranges than fumes could be detected - the radar in the nose of the P-8 is a high speed mechanically scanned antenna *specifically* to allow for increased sensitivity in periscope detection at the expense of other modes (no AESA). The radar spins so fast its in vacuum sealed space in the nose IIRC. So I find it surprising a sesnor for hydrocarbons could possibly be useful, but there you go:

GAO report, so I think this is the most primary source I can find:


"The P-8A program entered development with none of its critical
technologies mature. Since then, the program has made several revisions
to its critical technologies. One of the two current critical
technologies is mature; the other, the Hydro-Carbon Sensor, is expected
to reach maturity by September 2009. In October 2008, almost all of the
expected design drawings had been released. However, the design may not
be stable until the program completes technology development and
developmental testing. The program has initiated fabrication of test
aircraft, with the first scheduled to be delivered in August 2009. A 2-
month strike by Boeing machinists in 2008 may result in schedule delays
and increased costs. The P-8A has already experienced a $1.4 billion
contract cost increase, and is currently managing weight growth to
ensure that the aircraft will meet its key performance requirements. "


"In mid-2008, the Naval Air Systems Command (NAVAIR) deleted the requirement for the P-8A to be equipped with magnetic anomaly detection (MAD) equipment. This was part of a NAVAIR-directed effort to reduce P-8A aircraft weight by 3,500 lb (1,600 kg) to improve aircraft range and endurance. P-8Is destined for the Indian Navy will continue to retain MAD. The P-8A will use a new hydrocarbon sensor to detect fuel vapors from diesel submarines and other conventionally powered ships. "

MHalblaub said...

Dear folks,

LIDAR has one problem. It can not distinguish between smoke of a diesel powered fisher boat and a diesel powered submarine.

Therefore a clean diesel would be nice for the next Australian submarine.


Josh said...

Just because I think our posts might cause confusion, the 'stock' radar in the nose of the P-8 is the APY-10. This is actually a mechanically scanning set, as it was determined rapid mechanical scanning is actually superior to an electronically steered beam in the periscope detection mode. AESA was deliberately not used for this reason. There are surface search, weather, air to air (tanker) modes as well. The AN/APS-154 is a follow on to the Littoral Surveillance Radar System which is a belly mounted side looking AESA radar primarily used (apparently with great success in Afghanistan) for land surveillance. A number of P-3s were fitted with this system though it prevents the bomb bay from being used. In the P-8 the bomb is moved to the rear of the aircraft such that a long belly fairing can be fitted while keeping the bomb bay doors clear. The AN/APS-154 might also have some kind of periscope mode, though I suspect it more often would be used for SAR/ISAR/GMTI.


Josh said...

Something I just thought of - I wonder if there's anyway of detecting the fumes from an AIP plant. I suspect those would differ substantially from regular diesels (PEM cells would be undetectable). THAT would be a neat trick if it could be done, though I suspect both due to the amount of exhaust and its dispersed nature under water that it would be far harder, likely impractical, to detect.


Peter Coates said...

Hi Josh [9/2/16 6:23 AM]

It seems that CO2 and heat created by AIP functioning are potentially detectable (by sniffers, LIDAR and Infrared sensors). So CO2 and heat needs to be "diluted" to normal background levels.

My article http://gentleseas.blogspot.com.au/2014/08/air-independent-propulsion-aip.html of August 5, 2014 indicates:

"The [Spanish S-80 sub's trialling of] bioethanol-processor [AIP] also produces a stream of highly concentrated carbon dioxide and other trace gases that are not burned completely during combustion. This gas flow is mixed with sea water in one or more ejector venturi scrubber and then through a CO2 Removal System and whose purpose is to dissolve the "bubbles" of CO2 in water to undetectable levels."

Also see https://en.wikipedia.org/wiki/Ejector_venturi_scrubber