Immediately after The Great Escape the Royal Navy and Royal Canadian Navy started to set up a torpedo factory in Canada. After a brief interlude with Canadian-Vickers, the torpedo working group set up an Annex to the Northern Electric Company plant in Montreal. This facility was initially to refurbish existing RN torpedoes pulled in from all over the world, with specialist equipment again dredged up/contributed from Commonwealth sources, mostly Singapore DY and the RAN.
Australia's own domestic 18inch torpedo program gets packed off to Canada at this time along with its key personnel. The trade off was that the RAN got the available reserve of 18inch torpedoes in exchange for their stock of 21inch and all this kit. The logic behind that was that the RAAF was getting Beaufort at this time and its original role as a torpedo bomber was effectively their big stick at sea. That made 18 inch torpedoes worth more than 21inchers to them. To supplement the limited and wasting supply of RN 21inch torpedoes in Canada, they appealed to the US. This produces a limited supply of USN Mk10's modified to work in RN tubes. These were pure straight runners, with no adjustments in tube, they could be fired and that was it. Supply was also limited as the USN liked those for its own training. Fortunately, the fact that the RN were firing warshots and the USN could train with Mk14's, created enough slack to provide sufficient torpedoes to tide them over for a while. However it was obvious to everyone that the Mk10's were just a better expedient and wouldn't last forever. With submarine production in Canada on the program, there was a need for a new long term source. The obvious method was to use US torpedoes, so quite early in the war USNTS Norfolk prepared a small batch of 'Mk14CW' and send them north.
These torpedoes were tested on lake St. Louis and found to run deep. They were sent to the British submarine depot ships that had escaped as a part of the Great Escape where they were dismantled, the problem located and a fix applied. Even then, these torpedoes had only limited interoperability with RN tubes (say they get either the gyro or depth spindle to line up), and were fitted to take the old nose pistols from the USN MkII - the USN mag/inertia pistol being nationally sensitive.
Fortunately for the USN, torpedo consumption did not prove to be particularly heavy (depth charge consumption was another matter). A proposed plan to see Alexandria being reopened and a new torpedo plant at Keyport set up was discarded. Alexandria got reopened but the site and resources intended for Keyport went to production of anti-submarine weapons including depth charges and Hedgehog. Unfortunately there had been little preparation for expanded production though civil subcontractors. The Canadian factory fitted into the picture as a major sub-contractor in place of US firms.
Under this scheme they would make subcomponents for US production and be supplied with enough of the components they didn't make to assemble the torpedoes needed by the RN/RCN. One key element they didn't make was the turbines. These were an industrial challenge to make so it would be easier for Norfolk to work with a contractor closer to home, and they could well be seen as nationally sensitive technology. So by not having the Canadians make engines it kept them tied to the US for torpedoes and out of the technology with all the useful commercial and political effects this would have. But by allowing the Canadians to assemble the torpedoes they need it means they can modify them as required to work with RN tubes and it spared the US from having to bother with it.
The tests on the Mk14CW led to a major convulsion in the torpedo program. Norfolk threw a tantrum over the St. Louis tests, calling the Canadians all sorts of nasty names and claiming they had no right to test their product and were violating US national security. Admiral King got to hear of the row, investigated the situation and blood flowed. Eventually, sanity was restored but trust in the "official" torpedo design establishment was lost and the USN went looking to the universities and commercial labs for torpedoes development. Another effect of this convulsion was that the Canadians decided to work towards making a clone of the 21inch MkVIII* as insurance in case the US ended cooperation, In any case Northern Electric are well set up to help manufacture torpedoes. There are also costs to defray, which is the other side to the Canadian effort being absorbed into the US torpedo production program as a major subcontractor.
At this point the USN still had an unknown problem with their fancy pistol, and the RN had a reasonable supply of torpedoes that only have a limited interface with their tubes. There were two additional other drivers at this point, technical development in torpedoes and Canadian submarine production. The Canadians still had to use US periscopes (Kollmorgan's), as their construction was well beyond Canadian industry in the short to medium term - it would have taken them at least five years to build up the industry to make them. So with USN torpedoes, and USN periscopes, in a logical world the new submarines coming out of the Canadian Vickers yard would be fitted with USN tubes and the rest of the USN's TDC and sensor fit. It wasn't possible to get the best out of the USN torpedoes without the rest of the system.
This was a severe problem. The Canadian Vickers Yard had been built to produce H-class submarines in World War Two and had been mothballed thereafter. Plans to revive it had already been set in motion prior to the Butler-Halifax Coup and accelerated as soon as Canada found itself on the receiving end of Halifax's cold shoulder. However, the yard was sized for the 500-ton H-class submarine and anything much larger would mean a major rebuild. However, in 1936, the British had produced a modernized version of the H-class for use as a training and coastal submarine, designated the U-class. At 540 tons, this was eminently suitable for building in the Canadian Vickers yard and a group of U-class hulls were constructed. The design was then developed further, construction being welded rather than rivetted and, of course, American-supplied periscopes, torpedo tubes and diesels replaced their British equivalents. This design became the V-class
However, the USN's TDC was a big, sophisticated bit of kit, and the V-class were simply too small to accommodate it. The US also saw their TDC as nationally sensitive. In comparison, the RN's 'Fruit Machine' was small, compact and primitive. The TDC was, at first, not offered to the Canadians for security reasons, and thenr politely rejected on cost/volume grounds. The Canadians simply combined the USN periscope, tubes and some elements of sonar with the basic RN box adapted with Selsyn inputs/outputs. This left RN skippers still going to be shooting by mental arithmetic and seaman's eye, assisted by the Fruit Machine's best guess. This didn’t upset them since they'd always done things that way, only now the FC box had direct feeds from the instruments and gyro angles could be dialed in from the bridge rather than passed forward by word of mouth.
This left Northern Electric making two torpedoes. As Norfolk used CW (CommonWealth) for the RN derivative of the Mk14, and the current RN Mk sequence ended at 10, the Canadians called their initial
version of the Mk14CW the Mk.XIC with asterisks for later mods. This fish was specifically for existing RN submarine tubes and was, in all respects ,identical in performance with the standard USN Mk14, but was fitted with the RN impact nose pistol (being made in Canada). As war experience built up, more functions were hooked up, leading to three revisions of the basic design.
During the depths of the early torpedo shortage the RN/RCN also drew heavily on the stock of RN Mk.IX (and earlier) torpedoes from destroyers and cruisers. These needed to be replaced, which was no great drama, Norfolk just shipped up the required number of USN MK15 bodies for Northern Electric to assemble just as they have been doing with the MK14. - This (obviously) became the Mk.XIIC. The MkXIIC was a step backwards from the Mk.IX in range and speed, but it was a lot better than empty tubes.
Since the Canadian V-class subs had US torpedo tubes they need US specification torpedoes so Northern Electric made a straight MK14 for them, which became the Mk.XIIIC. These three torpedoes became the baseline for all subsequent Commonwealth torpedo development with 21inch Mk.XIC equipping British built subs, 21inch Mk.XIIC equipping RN DD/Cruisers and 21inch Mk.XIIIC arming Canadian built submarines with USN type tubes. All come from the same basic stock of original US components and modified Canadian components.
In retrospect, the Canadians could probably have used US produced Mk14's and not bother building them in Canada, but torpedoes were not only expensive, they were the RN's primary weapon in the war so consumption was heavy and the British government was very short of disposable funds Added to this was simple inertia. The Canadians had started making torpedoes (Mk.XIC), made a good number of them and the arrangement was working well. Finally, the US had scaled their torpedo production to meet their anticipated demand then adapted that plan to meet reality. At no point in the planning process had supplying whole torpedoes to the Commonwealth figured. The U.S. was already beginning to feel the pressure of wartime production demands and bottlenecks were beginning to pinch heavily. A few US Mk14's did get used in RN/RCN submarines but the bulk came from Canadian production.
With the initial emergency over, development kicked in. Torpedoes were the RN's primary weapon and one that they were gaining a great deal of experience in using. As time ground on, this experience translated into demands for changes made to their torpedoes. To the Commonwealth submariners, the natural place to take their ideas was Northern Electric not Norfolk. Once the grotesque and unworkable demands were quietly discarded, the requirements were for more speed, more range and less wake. Lurking in the background were also electrically-powered and homing torpedoes. However, improving the existing thermal torpedoes had priority.
Almost by definition, this meant a split away from the American line of development. U.S. research was aiming at a high-test peroxide torpedo and the Canadians had grave doubts about the viability of that concept. Economics though (and political concern over the control the use of American engines gave them over the Canadian torpedo program) pushed the Canadian Navy to examine reverse engineering the Royal Navy's Brotherhood-Burner engine in Canada. The two engine technologies were equal at this time, but turbines were a more specialized product and less understood in Canada, whereas the reciprocating engine was much easier to build even if mechanically it is a lot more complex. The thing was, the technical competence to build the Brotherhood-Burner in Canada was available to them. So the BB engine provided Canada with an engine it controlled and could work on, while reducing their imports from the US. It was also something they can do fast. It wasn't that easy to do but the Northern Electric had all the technical data and experience they needed on hand, and any competent tool room could make one up just as quickly as the castings could be made. The Brotherhood-Burner torpedo became the Mk.XIVC and this progressively replaced the Mk.XIIIC on the V-class submarines.
Another field was opened up when the German submarine U-571 was sunk in shallow water while attempting to land saboteurs on Long Island. The wreck was salvaged and in the torpedo room examples of a full-sized electric torpedo, the G7e. This had been designed to aid German submarines attacking into the teeth of a respectable ASW defense and was obviously of interest to the Allies. Westinghouse were prime contractor for copying the G7e with Northern Electric integrating the electric drive into the torpedo and taking on a big slice of the production. This became the Mk18 in US service and the Mk.XVC in Canadian and British use. By 1947, 65% of torpedoes fired by RN/RCN submarines were Mk.XVCs.
With The Big One, abruptly ending WW2, Australia put in a bid to recover its equipment and personnel. The Canadians were demobilizing quickly and saw little need to maintain a torpedo development capability. As a result, by the mid 1950's the entire design and torpedo production capability had been moved from Canada to Australia. This coincided with a need to reassess Australia's need for torpedoes. The submarines taken over by Australia as part of the Imperial gift were all pre-breakout Royal Navy. The small, short-ranged U- and V-class boats were of little value to the Australian Navy and funding did not allow the purchase of more than a handful of X-class boats. So, an assessment of future needs suggested that the RAN's submarines needed an electric torpedo for anti-trade work, an electric homer for ASW/anti-escort and a simple high performance torpedo for insurance and close work. The surface fleet still needed a 'standard' 21inch torpedo for its DD's etc, and a heavy weight homer for ASW. In addition, the RAAF need a lightweight homer for ASW.
On checking their inventory, the Australians found they had a wide variety of 18inch torpedoes, a handful of 21inch Mk.VIII* and 21inch Mk.IXs, stocks of 21inch Mk.XIC, 21inch Mk.XIIC, 21inch Mk.XIIIC, 21inch Mk.XIVC and 21inch Mk.XVC plus a handful of American-supplied MK24/MK27. So, it would make sense to retain the 18 inch as the RAAF's lightweight and the 21 inch as the standard fleet torpedo. Within that constraint, much would rather depend on what type of Tube the RAN picked to standardize on. Here, the status-quo counted. Most of their subs were old RN, the US was friendly but no ally so the RAN adopting the RN tube but added a three spindle (gyro, speed, depth) capability to give a tube that was not compatible with the US. To mark this change, the Australian Navy decided to drop Roman numerals for Arabic.
An initial post-war retrofit and modernization program gave the following torpedoes.
21inch Mk.16. This is the old Mk.VIII*** equivalent with enriched air for submarines. It was the Australian Navy's first line torpedo in the 1950's and early 1960's but lingers on as a second string weapon to this dauy.
21inch Mk.17 - Mk.IX*** Surface fired version of the Mk.16 for cruisers and destroyers. It was the main surface ASuW torpedo until that capability is withdrawn.
21inch Mk.18 - Mk.XVC based electric straight runner for submarines, seawater battery and evolved design
21inch Mk.19 - Mk.18 based passive homer, with guidance based on MK24/MK27 at least in theory. Simple but workable. Sub and surface launched
Those four are the first generation of Australian built torpedoes. They were very much regarded as an interim stage pending the delivery of a genuine "Australian" torpedo. As might be expected, their designation as an "interim solution" guaranteed a long service life.
The second generation of Australian torpedoes came as a result of the solid linkage between Sweden and Australia as a source of naval weapons. This resulted in Australia adopting the Swedes High Test Peroxide torpedoes as a cooperative venture, with tropicalisation, trials and finally domestic production. However, the main priority was the development of a better electric torpedo in both guided and unguided form. It was already perceived that the primary task of the RAN's submarine force in the Australia First period would be going to be after Japanese invasion convoys. This meant that escort suppression and killing merchant ships was the primary concern. Later, when the Japanese navy started to introduce SSBNs and SSGNs, ASW became a major driver.
After a couple of failed attempts, the Australian Navy finally produced the 21inch Mk.2 in the early 1960s. This was a 'programmable in the tube' one size fits all Universal torpedo. It had a seawater battery that gave it a speed of 27-30 knots out to 15,000 yards and programmable speed. Its primary limitation was a small warhead that demanded a magnetic fuse. This becomes the basic tool of the the RAN's submarines and the basis for a long lived family, that matured over the years, with the guidance system updated to wire and so on. The tactical doctrine behind its use was to fire off a full salvo with a mix of Mk.18's at the convoy and Mk.21's at the greatest threats then get out. After reloading, the attack would be repeated with two more Mk.21's in the stern tubes to cover the retreat.
The Mk.21 got updated every 5-10 years with increasingly fancy guidance and propulsion. However, its small warhead and relatively low speed meant that it was becoming increasingly outclassed by its primary targets. In the early 70's the Australian Navy adopted a Swedish HTP torpedo as the Mk.22 for ASW and Anti-Escort use. This was fast and had a heavy warhead but was also very noisy. Accordingly, it was reserved for high-risk targets with the modernized Mk.21's for firing at convoys as per the Mk.18/Mk.21 mix of the 60's.
Carrying two types of torpedo (at least, most submarines carried at least a couple of old Mk.16s to handle those really-hard-to-sink targets) was a pain. There was a demand for a new, high-speed, very discrete torpedo to replace both the Mk.21 and Mk.22. High speed and high discretion were, of course, mutually exclusive but hydrodynamic advances made some reduction in noise possible. The new Mk.23 torpedo used propylene glycol dinitrate (the major component), 2-nitrodiphenylamine, and dibutyl sebacate fuel. This gave very high speed and long range. The Mk.24 version of this torpedo had a nuclear warhead.