Thats just it. They cant stay at 20 knts on AIP. 5 knts is more like it. To go any faster they have to use their batteries. And sustaining 20 knts on battery would force them to recharge which would leave them vulnerable.
The SSK/AIP subs can sustain 20 knts on AIP power for at least 24 hours, it's probably a bit more, but classified, but I've seen it written several places and on several graphs in various papers that there is enough fuel in all the various AIP systems on the varying subs to give them around 1000km range at max power before running the fuel cell out. 5 knts is the sustained cruise speed on the AIP for 3 or 4 weeks without having to snort. I wasn't talking about AIP, AGAIN, when the SSK's are transiting to the operational area. The crossings are done on D/E power, and, like I've said to you twice now, at speeds between 10 to 15 kts. Even in the second world war the US and German fleet subs transited to operational areas in the double digits speed wise. Are you saying with your "humble" request for references that modern subs aren't going that speed?
http://gentleseas.blogspot.ca/2012/03/australia-should-choose-nuclear.htmlTHat is one of three places I've read that AIP powered subs burn off most of their AIP fuel source in approximately 24 hours at 20knts or greater. Pretty simple math to get 1000km range, 20 kts x 24 hrs = about 1000km or more. Regarding crossings or long distance sorties, I'm not sure why or what you're asking for. How is it you think I've hoodwinked you somehow by saying modern D/E/AIP SSK subs do? A relative of mine who was on the Canadian Oberon classes and then the Victoria class for a short while before retiring said they carried more than enough diesel in their tanks to bring the subs home from the UK when they bought them at speeds of 12 knts or better, and they aren't AIP equipped, just D/E.
This is what I've said and maintain - AIP subs can run roughly 24 hours at max power, at least 20knts, likely more but it's classified, until they exhaust the fuel cell or other AIP fuel being used depending on the type. At 5 knts, they can cruise on the AIP for weeks, even up to a month without snorkeling or using the battery charge or diesel to recharge the battery. Cruising 10, 12, or even up to 15knts on the batteries while constantly snorkeling and running the diesel, or surfacing to fast charge as well, they can cross oceans easily, and that's precisely what they do when they operate long distances. Do you think that while transiting to the USA for excises the AIP subs that have come ran at 4 kts on diesel/elec power? The absolute minimum speeds they run is 8-10 knts while transiting, and that is part of a formula based on detection vs submerged speed of economic advance, and stored energy levels. The charts on the below show that sustained long term cruising at 8-10 kts is very easy for most of the modern D/E/AIP subs listed, and 10-15 kts is no stretch at all, and just requires 2 to 3 snorts a day instead of 1 to 2.
http://media.bmt.org/bmt_media/resources/33/SubmarinePowerandPropulsion-Trends%26Opportunities.pdfThis paper also shows that 12 knts is the typical transit speed of SSK/AIP submarines, and while transiting they are typically near the surface and snorkeling as needed to maintain that speed.
http://www.bmtdsl.co.uk/media/1057740/BMTDSL-Optimising-SSK-Transit-Performance-Confpaper-Pacific-Jan12.pdfA quote from the above:
At submerged speeds greater than 14kts, it becomes beneficial to increase the proportion of the transit distance spent on the surface.
This is stating that once speed increases to 14 kts, snorkeling operations start taking up more time in the equation, as speeds are usually reduced to around 5 to 7 knts for snorting, so running on the surface to charge the batteries again is a faster way to do it, and get back submerged and back up to the 14 kt transit speed.
It's pretty obvious from all I've heard and read that SSK/AIP subs typically use high power diesel and electric propulsion for transiting to the operational area, and then use primarily the AIP system to stay covert, and once in the operational area only use their battery charge in certain situations where it is a tactical requirement, ie having to escape or evade surface contacts or other enemy submarines, to avoid burning off AIP fuel unless absolutely necessary.
That should satisfy your humble reference requests. I can post up a dozen other similar links and papers, but it'd be a waste of time repeating the obvious and self evident. Google it yourself if you think any of the above is incorrect, and produce your own references as to why.
