Countering the Zero: A Small Firm’s Contribution

It didn’t take long after the December 7, 1941, attack on Pearl Harbor for American pilots to fear engaging the Japanese "Zero" fighter plane in combat. Time and again, the agile Mitsubishi A6M would out-turn its rival in dogfights, allowing skilled Japanese pilots to gain the aerial advantage. Lightweight construction, positioning its engine and fuel tanks close to the cockpit and employing a lightened empennage produced a reduced moment of inertia. This "second moment of mass" describes a vehicle’s resistance to rotational motion. The low weight of the A6M also enabled it to out climb rivals.

The design of U.S. fighter aircraft stressed heavy firepower, durability, and pilot protection, including both armor and fuel security. In addition, the airframes of Navy aircraft such as the Grumman F4F-3 and F4F-4 were more heavily constructed than land-based fighters like the Curtiss P-40. This helped them overcome the rigors of landing on aircraft carriers. Together, these features resulted in more weight, increased moments of inertia, and lessened climbing capability.

By mid-1942, however, new tactics were devised that countered some of the Zero’s inherent advantages. Tactics included the "Thach Weave," an aerial combat maneuver developed by Navy pilot John S. Thach. And in 1943, superior carrier fighters including the Grumman F6F Hellcat and the Vought F4U Corsair arrived to support the Pacific fleet.

When taking fire, Mitsubishi A6M Zeros often burst into flame or exploded, because they lacked the self-sealing fuel tanks that protected American flyers. In contrast, Japanese pilots complained that multiple salvos fired into U.S. fighters often failed to hinder their flight.

The self-sealing fuel tanks (also called fuel cells) of U.S. aircraft were constructed of layers of reinforced fabric and rubber. Entrance holes made by bullets were quickly sealed by the action of the gasoline on untreated rubber. The rubber swelled and closed the hole, preventing massive leakage and possible ignition and/or explosion.

However, laboratory experiments reported in the 1946 Naval Institute Proceedings showed that a bullet’s high-speed impact often burst slab-sided tanks. As Edward Eckelmeyer, Jr. wrote in Vol. 72/2/516 [see previous article], this was only avoided by building the tank as a unitary construction, carrying alternate layers of materials around rounded corners to adjacent sides to distribute the stresses of impact.

This measure complicated the cell’s construction in two ways: First, the entire cell had to be constructed at one time rather than assembled from separate parts. Second, it had to be built over a form. The form duplicated the inside configuration and dimensions of the completed cell. It provided the base upon which a worker would successively accumulate layers of reinforced fabric and rubber. This construction technique required the form to be removed before the fuel cell could be installed—a difficulty that was not easily overcome.

My uncle, Serge A. Rivard (1905-1987), proposed that the form for a fuel cell be made of corrugated cardboard. Piping live steam into the fuel cell’s interior would collapse the cardboard. Within a short time, the hot steam would reduce the cardboard to its original nature as wood-pulp and water. Subsequent flushing via its hose connections removed the pulp-water mix from the cell. After cleaning and drying, the empty fuel cell was now ready to be installed in a warplane on its assembly line.

The United States Rubber Company in the small town of Mishawaka, Ind., accepted the concept and Rivard Products Company was formed to produce the needed cardboard forms. Within months, an existing warehouse on the bank of the St. Joseph River was leased and production of forms begun. My father, Earl J. Rivard (1907-1996), Serge’s brother, became the . . .