All and Nothing

After Pearl Harbor, the Japanese planned to strike the United States with aircraft borne by giant submarines.

The Aichi M6A1 Seiran (Clear Sky Storm) (shown here on a beaching dolly) was designed to operate from a submarine. (NASM)
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We knew most of the work would be on the bottoms, so we turned the floats upside down and started removing the skin panels. We knew we couldn’t just do a cosmetic repair because the aircraft would be displayed on its floats, so the floats had to be structurally sound.

Some sections had rivets that had completely turned to powder. The corrosion looked like it probably started on the inside and worked out. The float had probably filled with water—in fact, we could make out a water line inside it.

We took out the bad sections on one entire float and made wooden forms from the original parts. We used these to hand-form the replacement sections from .040-inch aluminum sheet. We annealed [softened] the aluminum and shaped it with a mallet.

We did 75 percent of the re-skinning job solo until we got to the keel, which is on top with the floats flipped the way they were. The access hatches that would normally be on top of the float were on the bottom where a person could crawl inside with a light and a fan and a whole bunch of bucking bars. Because of the location of some of the rivets, we had to fabricate bucking bars. Finally we got to where we had to have someone inside the float. A person can work about two hours in there before they have to come out. Once they were inside it wasn’t too bad. But getting in was tough.

Tyrone Stewart: [I worked inside the floats] for about three weeks, and it was hot in there! The hardest part was near the end portions, where the float narrows. I had to crawl out, then climb back in again every time I needed to change my position.

Bill Reese: The engine was taken off the firewall and set vertically while we worked on it. It was fairly easy to remove. We pulled the cover off the bottom of the block to see the big ends of the connecting rods and crank. We looked inside the cylinders and saw that there was only a light coating of carbon, so it had less than 10 hours on it. We went inside with a spray wand and some corrosion inhibitor and did some touching up here and there. There were no earth-shattering surprises. It was fun for me as a mechanic to work on such a rare engine. It’s complicated, and it’s a big chunk of metal—that made it a lot of fun. But curiosity is not a good enough reason to tear an engine completely down. You start tearing it down and you can do more damage than if you leave it alone.

Matthew Nazzaro: The fuselage had been outside most of the time, so it had sun and water damage. Souvenir hunters had been at it as well. There were areas where aluminum and steel were joined without coatings between them, setting up electrolytic corrosion cells.

Robert McLean: The first record of the [propeller spinner that accompanied the Seiran] was some photographs taken around 1960 when the aircraft was on display at an open house at the naval air station in Alameda, California. There is a mysterious blue spinner nose that didn’t look right in these photographs, and later, during restoration, we found that this blue nose section didn’t really fit the spinner base, leaving a gap. The shape didn’t look right, the color was wrong, and rivet holes at the rear end of the spinner nose had no purpose.

Inside this blue spinner was penciled “RH” in an English or European alphabet, which suggests that this was not a Japanese spinner and possibly was the right-hand spinner of a twin-engine airplane.

Nazzaro: [After studying photographs] we decided that the spinner nose of the Suisei [the Japanese “Judy,” similar to the Seiran] was longer than that of the Seiran, but the actual spinner bases from the two aircraft were identical. This provided us with an excellent starting point, knowing that all that was needed to plan the new Seiran replica spinner nose was an updated profile, with construction techniques based on the longer Suisei nose.

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