A6M1 Drawings
Evidence and Theory Presented by Jim Long


Part Five

The last of the A6M1 drawings were in the Koku-Fan Monthly installment for November 1974. These were on pages 187 through 190 and were mixed with some items on the A6M2 and A6M3.

Page 187 illustrated the engine cowl flaps and the exhaust manifolds. The drawings were laid out in landscape style, with the four diagrams on the left side of the page applying to A6M No. 37 and after. The four drawings on the right side of the page applied to A6Ms Nos. 1 through 36, which of course includes the two A6M1s.

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(Page 187 from the November 1974 issue of Koku-Fan Monthly.)
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The original illustrations were probably on four sheets of paper, two showing side and front views of the cooling flaps and two showing side and front views of the exhaust pipes. Note that the two drawings of the cowl flaps at the bottom of the right-hand group were reproduced at a scale different from the others. Those two drawings were reproduced in a smaller size.

Although the right-column drawings apply to the two A6M1s as far as the cowl flaps and the exhaust pipes are concerned, the side and front views of the engine cowling and the carburetor and oil-cooler air intakes do not. These details are shown as they applied to A6Ms Nos. 3 through 5, the first three A6M2s, which were of course equipped with Sakae 12 engines. You can see that they had air scoops at the bottom of the cowling to feed their updraft carburetors, and they had horizontally mounted oil coolers in large housings below and behind the carburetor air intakes.

On page 188, two sets of drawings once again illustrated differences between planes. This time the drawings show the long-wire antenna system and point out the differences between A6Ms Nos. 1 through 6 and A6M No. 7 and after. On the first six A6Ms the streamlined antenna mast was angled forward at 22.5 and was aligned with the fuselage centerline. Beginning with A6M No. 7, the mast's angle was changed to 10 forward and the alignment of the mast was at about 6 to the left of the fuselage centerline. These differences could have been shown on two profiles of A6M2 aircraft, but lucky for us the draftsman used the drawings that had already been prepared to illustrate the A6M1 configuration, which also applied to the first four A6M2s, merely relabeling the drawings to indicate that application.

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(Page 188 from the November 1074 issue of Koku-Fan Monthly.)
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The profile at the top of the group on the left side of the page is of the rear portion of the fuselage of an A6M1. This important drawing shows the low position of the horizontal tail (at the fuselage reference line) and the characteristics of the broad and pointed vertical tail.

Something that may go unnoticed is the fact that the profiles of the fuselage rear sections exhibit evidence in support of the idea that the rudder on the No. 2 A6M1 could easily have had an aerodynamic balance area forward of the hinge line at the top of the tail, either as an original installation or as a refit. Notice that the hinge line of the rudder is indicated by a vertical line drawn right through the diagram. The same is true of the hinge line on the A6M2's vertical tail, though the line is somewhat shorter. In both instances it is the hinge line that is being indicated, not the actual profile of the rudder itself.

This is evidence to show that the rudder of the No. 2 A6M1 may have been similar to that of the A6M2. A photograph of the wrecked second A6M1 on page 34 in Robert C. Mikesh's "Zero: Japan's Legendary Fighter" actually shows that the pictured A6M1 did have a balance area. It can be seen at the top of the photo, along with the notched-out area on the fin to accommodate it. You will have to ignore the photo's caption material. It is in error and would have been corrected in a new edition planned for publication in the Japanese language. The revised caption would have identified the plane as A6M1 No. 2 (s/n 302) that had crashed on 11 March 1940, killing test pilot Masumi Okuyama.

A different version of the A6M1's antenna drawings was in the handling manual reproduced in Model Art Publication No. 323. It is diagram 169 on page 143. It shows a complete profile of an A6M1. It doesn't have an external carburetor air scoop. But it does have an oddly shaped oil cooler scoop at the bottom of the cowling, which we know to be contrary to the shape of the actual oil cooler air scoop that can be seen in a photo of one A6M1 airframe. One artist has assumed that this shallow oil cooler scoop was real, at least for the No. 1 A6M1 as it was originally built, and he has illustrated the A6M1 with a shallow scoop at the bottom of the cowling.



References

9. Robert C. Mikesh, Zero: Japan's Legendary Fighter, Motorbooks International publishers & Wholesalers, Osceola, WI, 1994. This book has the photograph of A6M1 No. 2 in its wrecked condition on page 34. Pages 85 and 86 have a paragraph on the A6M1's carburetor air scoop.


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