Nakajima A6M2-N Rufe (oz14029)

About this Plan

Nakajima A6M2-N Rufe (Navy Type2 Fighter Seaplane). Radio control scale model Japanese WWII floatplane. Wingspan 58-11/16 in, wing area 577 sq in, for .50 to .60 engines.

Note this plan is derived from the raw (greyscale, 200 dpi) scans as posted on HPA by danito69 - see datafile. This version here has been cleaned up to remove paper creases, then saved as a 2-colour 400 dpi bitmap.

Note the parts supplement file is a modern redrawn file in vector format. Note: These parts sheets were drawn up by Larry D Philip (see comments).

Update 27/8/2024: Added kit review from Radio Modeller, February 1984, thanks to RFJ.

Quote: "RM Kit Review: Marutaka Nakajima A6 M2-N. Kit reviewed by Roy Tassell.

With a wingspan of 1490mm and a designed flying weight of 2.9 to 3.6kg, this 1/8 scale model of the famous 'Float Zero' is designed around .60 engines and five function radio control. Distributed by Irvine Engines, the kit costs £94.25.

ESSENTIALLY a floatplane version of the Mitsubishi A6M2 Zero-Sen, the Rufe was a stop-gap shipborne fighter until the Rex could be developed. Nakajima engineers took the airframe of the Zero, increased the tail area and added a ventral fin. A central float, braced by a single front pylon and 'V' struts at the rear, plus outboard stabilising floats mounted on single struts from the wings replaced the undercarriage. The project began at the end of 1940; the first prototype was finished in December 1941 designated the Nakajima A6M2-N and production began in April of 1942. US forces reported Rufe at Guadalcanal, later in the Aleutians and the home islands of Japan. The powerplant was a Nakajima Sakae 12, rated at 940hp and Rufe had a top speed of 270mph at 14,000ft.

On obtaining the Marutaka kit for review I was extremely keen to set to work and see the finished product, but on opening the box, examining the contents and spending two evenings studying the drawings, it was obvious that it would take some long and serious building to get near to seeing the final sliape and form of this interesting subject.

The contents were of a very high standard of materials and die-cutting, including a superb spun aluminium engine cowl and vac-formed cockpit canopy. The only items lacking were transfers and control surface hinges. As a signwriter by trade the lack of transfers didn't bother me, but I feel that they should have been included for those less skilful with a paintbrush. As there were no separate building instructions I had to decide for myself the proper order of building and fell into my old habit of going for the fuselage first, only to find that it should have been the tail unit.

The drawings (two sheets) are very com-prehensive and easy to read provided they are studied carefully for a couple of evenings before commencing. Also at this point the modeller should decide on his choice of engine mounting. The kit is designed with integral wooden Uearers so if you require an aluminium radial mounting, then modify with a quick pencil sketch before starting work and note also that the thrust line is offset to counteract torque.

Fuselage The box structure supporting the engine and wing was built first. This is formed entirely from ply and includes the main fuselage jigs and engine bearers. When this assembly was firmly glued together it was
quite straightforward to clamp it upright in the vice and slide all the formers onto the four longerons and add the balsa blocks (F.20-F.21) which form the wing fairings and the blocks (F.19) which eventually become the gun blisters in front of the cockpit. At this point the tailplane and fin were built and fitted into place on the fuselage with their balsa block fairings before commencing to sheet the fuselage.

Tail surfaces are straightforward but care has to be taken to keep them as light as possible. Large holes were therefore cut in the main rudder and elevator profiles (R.1 & S.10) and the blocks (R.4), which continue the curve of the fuselage over the lower part of the rudder, were hollowed out. The entire tail unit was fitted to the fuselage although the ply ventral fins were added after sanding.

The skinning was completed with thin strips of 1/8in. sheet. Having arrived at this point the modeller must put aside a complete evening for the sanding session. First, very coarse sandpaper is used to bring the blocking into shape with the sheeting, particularly around the area where the fin meets the tailplane, but remember to leave it about 1/16 proud for finishing with a finer grade. Do not touch the blocking around the wing bay until you have built the wing and offered it up to the fuselage.

The wing: This has a very thick aerofoil section and is extremely strong. Construction is again very straightforward if one follows the drawing closely. Do not add the sheeting until the central float is built and offered up so that its fixing can be finalised.

The central float is designed to be detachable and is bolted through the centre section of the wing, wherein also the hydro-dynamic rudder controls run. It is advisable to make the floats detachable if you feel that one day you may wish to convert the craft to a la ndplane. But in my own case I built as per the drawings and fitted the floats as in-dicated, but made them permanent with a touch of epoxy. After dry-fitting the floats, they were detached and the wing was sheeted and sanded. It is advisable to add an extra hardwood stiffener to the trailing edge at the flap position as this area is flimsy. When finished, the wing was offered up to the fuselage so that the latter's wing seating and fairings could be finalised. A point to note here is that the wing fairing blocks flare to a very sharp and therefore fragile point at the trailing edge. To prevent these being repeatedly broken off during construction; a piece of thick paper (the edge of the drawing in fact) was cut to the wing fairing shape and glued with household UHU over the fairing block. After doping and painting it made the fairing far more durable.

Floats: As with the rest of the model the built up ply and balsa central float fitted together like a well-cut jig-saw puzzle and completed while the wing was half assembled (before sheeting). It was jigged up in a vice, epoxied together and completely sheeted and blocked before sanding. The water rudder was fitted in place and its free working checked. Control runs for this were made from Sullivan Flexi-Push Rods, which despite a sharp bend at the bottom of the central pylon, worked quite freely. The drawings show the water rudder and aerodynamic rudder operated by the same servo, but in practice it was found that this was a serious mistake. The water rudder should have a separate servo of its own, for if on take off you wish to keep the model into wind with the rudder, the water rudder on the float will throw the model bodily to one side. The float rudder should only be used to steer the model at low speed on the water.

The wing tip floats are from injection moulded expanded polyurethane with a central ply former and a very heavy wire brace which runs through the centre of the strut and locks into the undersurface of the wing. This is an extremely heavy arrange-ment and its weight out at the wing tips was rather unwelcome, but due to the strength that these floats require, there was no way to avoid the weight. When taking off, these floats take an awful lot of fore and aft buffeting and should be secured into the wing as positively as possible. Otherwise they could be ripped off, taking the lower skin of the wing with them.

Finishing: After constructing the model, a faithful old Merco 61 was installed and the radio gear linked up. The aluminium cowl was dressed up with dummy hinges and catches made from litho plates and cooling gills engraved with an engineer's scriber before the cowling was sprayed up with a matt black cellulose aerosol. The airframe was covered with rag tissue (not Jap!) and given three coats of dope before the cockpit canopy was fixed in place.

I found it quite difficult to find colour references for Japanese floatplanes, but after spending a day in one of London's famous aeronautical book shops, I came up with a green scheme, which I applied with Humbrol Enamel aerosols (gloss) and added a bit of riveting and panel line detail with a silver paint pen (made by Pilot of Japan). Finally the whole thing was fuelproofed with matt Polyurethane varnish. 'Meatballs' (the Rising Sun national markings) were produced by painting white discs of the correct size onto wings and fuselage and when dry over-painted with a slightly smaller red disc. This is easier than painting the red disc first and then trying to work a thin white line around it.

The box art work is peculiar as this depicts the manufacturer's original model in a Prussian Blue finish and as far as my researches went, no colour scheme like this ever existed. Scale purists might also note that, unlike the Zero-Sen, Rufe did not have a pilot's head rest or wing cannons, although both of these are depicted in the drawings.

Flying: First flights were made on a very calm day and were preceeded by taxiing runs which were satisfactory, although they revealed that the Rufe has to be regarded as a flying boat as opposed to a twin float seaplane for the wing tip floats have to be taken into consideration. Fortunately all three floats touch the water when at rest, which gives the model a natural even keel for take-off. As previously mentioned, the water rudder has to be independent from the air rudder so that it may be left at neutral during the take-off.

The take-off run had to be fully gunned as the model is quite heavy with 2 oz of lead trim inside the cowling. The first take-off was made with the flaps deployed and these made the climb quite steep. At a safe height they were retracted and the model evened out into a steady flight for six or seven circuits. The first approach was quite fast and throttling back at the last minute caused the heel of the main float to cut into the water resulting in a semi-stalled landing, but a safe one. On its second flight all went as previously except that this touch down was much improved. The final touch-down should be in a semi-stalled attitude because of the way that all three floats are in the water when at rest. It is important to prevent the wing tip floats touching down simultaneously with the central float when alighting, to avoid an unnerving ground (water?) loop.

Summary: It is obvious that this model is intended for the more experienced pilot - in fact, during the initial flight trials I was quite frightened of it myself. Others might find it easier to fly but even so still find it a new experience. As for the building, it took a long time and I enjoyed every minute of it - a meaty one!

Marutaka should be applauded for their bravery in producing such a rare and specialised type and making such a success of the project.

Further reference 'Floatplanes' by William Green (McDonald and Co.); 'A6M Zero in Action' by Shigeru Hohara (Squadron/Signal Publications) No. 59 (ISBN 0 89747 141 5)."

Update 28/8/2024: Replaced the parts supplement file with a version that now includes the original credit statement to Larry D Philip.

Supplementary file notes

Parts, 2 pages.
Review.

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