Copyright 2011 by Brandon Cope 

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R-class transport submarine

One of the practical problems facing the Axis powers was the transfer of strategic materials between Europe and the Far Etas. Surface shipping was too vulnerable to the US and British navies and cargo planes over such a long distance were impractical. The solution was to modify long range patrol submarines to carry these important materials. However, such loads were fairly small compared to the displacement of the submarines. In 1942, the Italians laid down the hulls for a new class of large transport submarines which carried four times as much cargo as the patrol sub conversions and double that of the Typ XB (p.W:MP115). This was neither a new nor untested idea; in WWI Germany had sent the merchant submarine Deutschland to the US twice before  the US entered the war. There were two holds, one fore and one aft, with two cranes (which folded flush into the deck) for each hold. Only two of the twelve boats ordered were completed, the Remo and Romolo.  Launched in late March 1943, both had very short careers, being sunk in mid July 1943 before ever completing a trip to the Far East.

Although the R-class submarines had no effect on the war, in an alternate history campaign they might have some impact. Perhaps the Germans managed to finish some of the boats that were not completed. Also, with some additional life support equipment, the boats could be used as 'amphibious assault' submarines, carrying troops instead of cargo ...

The Remo has a crew of 63. Three 20mm AA guns are carried in single mounts on the foredeck, afterdeck and platform on the rear of the conning tower. The engines burn 77.5 gallons of diesel fuel per hour of routine usage. The Remo can travel 13,800 miles at 10.5 mph surfaced and 125 miles at 4 mph submerged.

Subassemblies: Medium Destroyer chassis with Sub option +9; sealed Medium Secondary superstructure [Body:T] +3; three retractable full-rotation Mini open mounts #1-3 +0.
Powertrain: 2¥970-kW marine diesel engines with 2¥970-kW water screws and 118,000-gallon standard tanks; 2¥336-kW electric motors with 7.15 million-kWs batteries†.
Occupancy: 16 CS Body, 5 CS Sup Cargo: 400 Body

Armor
Body: 4/55
Sup: 4/55
OM: 0/0

Weaponry
20mm Long Ground AC [OM1-3:F] (2,000).

Equipment
Body: Autopilot; backup driver controls; 5,450-VSP bilge; 15¥bilge pumps†; 62¥bunks; cabin, 2¥2,100-VSP cargo holds; 4¥10-ton cranes, 75-man environmental control†; 12¥fire extinguishers†; 80-man-days life support†; navigation instruments; precision navigation instruments; 5,670-man/days of provisions; 2-mile passive sonar. Sup: Navigation instruments; 2¥20’ 15¥ periscopes; 2¥very large radio receivers and transmitters; large radio receiver and transmitter, searchlight. OM1-3: Universal mount.
† Full access.

Statistics
 
Size: 232’¥26’¥30’ Payload: 1,021 tons Lwt:  2,606 tons
Volume: 32,650
 Maint.: 11 hours Price: $327,000

HT: 9
HP: 108,000 [Body], 750 [Superstructure], 30 [Open Mounts1-3]
 
wSpeed: 15 wAccel: 0.1 wDecel: 0.5(0.6) wMR: 0.05 wSR: 4 Draft: 18'
Flotation Rating 3,125 tons.
 
uSpeed: 7
 uAccel: 0.05 uDecel: 0.3(0.4) uMR: 0.05 uSR: 4 uDraft: 30'
Crush Depth 100 yards.

Design Notes
The 2,606-ton historical submerged weight was used for underwater performance calculations. Design wSpeed was 13 mph and uSpeed was 8 mph; the historical figures were used instead. The small destroyer chassis was about 1,000 VSP too small for the design; the one chosen, however, leaves a lot of excess space (over 4,000 VSP) that should be ignored.

Two external 533mm torpedo tubes could be fitted to the bow if required, but reloads had to be carried in cargo space and the tubes could only be reloaded when surfaced.

Variants
There were no historical variants of the R-class, although one or two hulls after the war was completed to the point of it being used as floating fuel tanks. In non-historical campaigns, there are a couple of options.

An amphibious assault version might use the rear hold to carry three pinnances (p.W:MP119) and one Ro.43 floatplane (or perhaps a verson of the CR.42 (p.W:GL34) equipped with twin floats and folding wings. The front hold would have accomodations for 85 troops an 15 crew, mechanics and deckhands for the pinnances and floatplane.

A rather more pulp/cliffhanger exploration version would again use the forward hold for accomodations, but with eight roomier cabins and only ten bunks, additional life support and a second galley. The rear hold would be partially given over to three labs, two workshops (Electronics and Mechanics) and a large (for submarines) sickbay, with three beds and a surgery, along with a two small boats (one 25' whaler and one 30' pinnance, both p.W:MP110), with remaining space used for exploration gear and provisions.

A third alternative is a missile boat, either as a joint Italian/German operation or Germany alone if it completed any of the unfinished boats. The least ambitious rote is to simply carry the equipment in the holds and assemble it on deck in firing range. This would include, for each hold, a launching ramp, two or three V-1 "buzz bombs" (P.WIC123) modified with folding wings, and JATO pods. As there was a manned V-1 project by 1944 but not a flood of German volunteers, the operation could take on a  fully Axis operation with willing Japanese aviators. New York City and Washington D.C. would be the most obvious targets for such terror weapons, but manned V-1's could be used for smaller targets, such as naval yards.