A6M1 Drawings
Evidence and Theory Presented by Jim Long
Parts One Through Six


When Dave Pluth called for us to revisit the A6M1 on 10 August 2001 in a note on the JAPANESE NAVY AIRCRAFT BOARD, I couldn't help responding with a comment about the external carburetor air scoop that he listed as one of the items necessary to make an A6M2 look like an A6M1. Dave listed five items of that kind and asked if there were any other features he had missed.

I posted a reply on 11 August in which I wrote that the external air scoop on top of the cowling was not really there, although almost everyone thinks that it was one of the main identifying features of the A6M1. Other people reminded Dave that the fuselage had to be shortened and that the horizontal tail had to be lowered to the fuselage reference line.

Those doings with the fuselage length and the horizontal tail are true and are agreed upon by most everyone. But you will not find general agreement among enthusiasts regarding the nature of the carburetor air scoop on the A6M1s and the characteristics of their vertical tails. A few of us believe that the carburetor air intake scoop was under the top of the engine cowling, and was not the bent elbow sticking out of the accessory section that has been illustrated in every drawing of an A6M1 since the 1950s or 1960s. We base our belief on authentic WWII Japanese technical drawings that show an air scoop under the cowling of an A6M1.

A few of us also believe that at least one of the two flying A6M1s had a rudder with an aerodynamic balance which was not unlike that of the A6M2. We believe that a photo of the destroyed No. 2 A6M1 shows that the rudder had an aerodynamic balance surface forward of the hinge at the top, just like the A6M2, with a notch in the fin to accommodate it. We are convinced that the rudder with the straight leading edge was unique to the A6M1 prototype only, as originally built, and that modifications were made as testing went forward on the Nos. 1 and 2 A6M1s and also an unnumbered airframe for static tests. Therefore, when it comes to illustrating or modeling A6M1s, a person must specify a time and a serial number that is appropriate to the plane being shown or recreated in miniature.

Drawings of A6M1s with external air scoops and straight-edged rudders got published in various books, perhaps as early as the 1950s, surely as early as the 1960s. To this day, these external scoops and straight-edged rudders are regarded as being the only true configuration the A6M1s ever had. But a few researchers and observers have different views. I, myself, have known since the 1970s that the business about the external air scoop was not true. In that decade of the 1970s I also came to believe that the No. 2 A6M1 had a revised vertical tail to incorporate an aerodynamic balance. A few of my closest associates agree with me. It all means that the various possible configurations of A6M1s must be considered before a drawing or modeling project can go forward.

It was in 1975 that my friend Charles J. "Chuck" Graham, former editor of the IPMS-USA Journal, sent me some most interesting excerpts from the Koku-Fan monthly magazines he had been receiving from Mr. Toda of the Bunrindo Company, the publisher of Koku-Fan. These excerpts, identified in this piece as Reference 1, were drawings of the Zero Fighter. What made them extremely interesting was the fact that they were obviously authentic technical drawings from some sort of Mitsubishi document or from a Japanese navy manual on the famous naval fighter. I was grateful that my friend had been considerate enough to copy these 48 pages of material and send them to me. This was stuff that was right up my alley, and I spent a lot of time and effort studying the diagrams and translating some of the labels. The Koku-Fan publisher had obligingly included some English labels; that was a great help.

To my great surprise and pleasure, I discovered that a few of the drawings actually related to A6M1s, that is, to the first two A6Ms, the experimental models with the Zuisei engines that had started the whole thing, but had been rejected in favor of a re-engined and modified model know as the A6M2.

When Robert C. Mikesh was asked by Motorbooks to produce a volume on the Zero in the early 1990s for its warbird series, he said to himself, to me, and to his publisher that the Zero had been done to death. He didn't know what he could write that hadn't already been written. But he agreed to do the project, and along with a score of associates, he enlisted me to help create the new book on the Zero. Bob permitted me to do some editing and writing of material for the new edition. I was given a by-line for the chapter I wrote on Zero serial numbers, and some of my other ideas were incorporated into Chapter 10, "The Zero Matures" and Chapter 11, "A Critical Look." On Pages 85-86, I was permitted to mention the carburetor air scoop of the A6M1 and the very real probability that it was under the cowling, not protruding into the air stream from the accessory section as illustrated in many drawings, including the three-view drawing on page 20 of the very book in which I was making the suggestion. That didn't help, of course. But Bob was compelled to use those drawings because they represented the majority view at the time. And still do, obviously.

I was basing some of my material upon what I had seen in the Koku-Fan reprints of the Zero technical drawings. The drawings had convinced me that the air scoop was under the cowling piece. And Bob Mikesh allowed me to say so in his new book that became known as Zero: Japan's Legendary Fighter when published in 1994. But since the statement about the air scoop was a short one and was not accompanied by an updated drawing to support the comment, it got lost. I didn't pursue the matter further - until now.

I think it is now time for everyone to see these old technical drawings. To that end, I have prepared the following presentation to be posted on the j-aircraft website by Dave Pluth. I believe this material will convince you that my ideas about the air scoop and the rudder characteristics are correct. But each of you will have to examine the material and come to your own conclusions. As for me, if I were to draw a diagram of an A6M1, if I were to build a model of an A6M1, or if I were to describe the A6M1 to someone, I would use the WWII technical drawings that appeared in the Koku-Fan magazines back in 1974 and my drawing, my model, and my description would embrace and reflect that data.

The presentation that follows fell naturally into six parts. There are five parts that discuss the five monthly issues of Koku-Fan's Zero technical drawings in which items related to the A6M1 appeared. These parts are illustrated with annotated pages from the pertinent Koku-Fan magazines and include lists of other references which have material related to the discussion. The sixth part is my conclusion, where I talk about A6M1 drawings that have been published over the years, and I identify the two important artists who have produced drawings of A6M1s in the 1980s and 1990s. There is also a list of nine other references which have material on A6M1s, from which four pages have been selected to be included in this presentation.

The excerpts from the Koku-Fan magazines, from Reference 5, and from Reference 8 are presented here under the fair-use provisions of U. S. Copyright Law. They are for your private use only. They should not be reproduced, published, or distributed further in a commercial publication or other similar media without specific permission from the Bunrindo Company, publishers of the Koku-Fan magazine, from the Model Art Co., Ltd., publishers of Reference 5, and from the publisher of Maru Mechanic. Securing that permission is the responsibility of the would-be user.

James I. Long, Owner
AIR'TELL Publications
& Research Service

Continue to Part I