masch3 wrote:
...what would be the possibilities to backdate the Trumpeter Repulse to her pre-war fit or even WWI fit??
Backdating the model to depict
Repulse in her post-modernization appearance (1936) up to October 1938, requires leaving the existing gunhouses mainly as provided by Trumpeter. The supplied 4-inch AA singles located atop these gunhouses would need to be replaced by twin 4" BD mountings. The kit-supplied #3 pompom on the flying-deck should be replaced as well, with a 4-inch triple mounting for any period prior to early 1941.
Some minor alterations to the flying-deck and island shelter would also be needed, mainly to remove the ventilator extensions and (possibly) correct the detailing of the guncrew shelter and some of the fittings beneath the flying-deck with a bit of scratchbuilding work--nothing too difficult from what I have seen so far (although I do not actually own the kit yet).
No 20mm AA was carried until very late in 1941, so any existing splinter tubs, footings, etc. for these weapons would need to be blanked or left off--including the locations either side of the forward director/rangefinder and those on "Y" turret roof. The 284 radar should be omitted, the seaplanes replaced (if desired to be displayed) with earlier types (either Sharks or Swordfish, depending on the retro-date chosen) and, if the kit includes it, 286 search radar omitted.
A second starboard anchor and limited cabling were also present before 1939, which should be added for accuracy (there was no third capstan/windlass for this, however). For 1936 only, the gash chutes on the ship's sides (immediately abaft the upperdeck 4"single mountings) and their protective mantlets, which are supplied with the kit, must also be omitted and new, unprotected chutes fabricated (or purchased) and installed, several feet forward of the 4"AA positions. For 1937 onward, this modification is not applicable.
The workshop roof (between the funnels) was fitted with cradles and carried spare seaplane floats until 1941 when Walrus seaplanes were embarked; no Carleys were stowed there until this happened, so any prior configuration should include this modification to the kit. Between 1936 and 1939, minor changes to the number and location of Carley floats were made, as well as paravane/boat booms and their locations. Ship's boats varied slightly in number and location as well, during this period.
For the ship's 1938 Spanish Neutrality Patrol/Mediterranean commission "B" turret was painted, as per nominal RN practice, with red, white and blue aerial recognition stripes. From her 1933-36 reconstruction until 1939,
Repulse was mainly painted in overall very light grey (close to 507c, if not that exact color).
For 1939 and 1940 builds, the kit's existing gunhouses and flying-deck/island shelter need to be altered, but the ventilator extensions remain as provided. The second starboard anchor was also gone by then; otherwise, many of the aforementioned details apply as above, i.e. workshop roof, radars, weapons, etc.
All in all, many year-by-year differences make for a fairly good range of possibilities; however, and to address the second part of your question, the work involved to backdate the kit to a WW1 configuration would be very extensive, requiring significant changes in the hull, as well as a complete overhaul of the superstructure.
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Danny DON'T "waterline"...!