(38)Where was the atomic bomb dropped?

3.8 km in the sky, east-northeast of the hypocenter

The atomic bomb is said to have exploded about 600 meters above Shima Hospital. It's easy to imagine, then, that it was dropped at a point above that. To check, I spoke with Kunio Nagata, 48, a science teacher at Ujina Junior High School in Hiroshima. In August, Mr. Nagata delivered a lecture in town entitled "Where did the Enola Gay drop the atomic bomb?"

"No, that's impossible," he replied, referring to my theory. "It was released from an airplane in flight." He went on to explain "the law of inertia" which is taught in the third year of junior high school.

According to this law, a bomb dropped from an airplane, just after its release, should continue to move horizontally in the same direction and at the same speed as the plane. However, in reality, gravity will make the bomb drop along a parabolic path, as in Illustration 1. This means that the atomic bomb was released short of the hypocenter.

How far short of the hypocenter?

Based on the testimonies from crew members of the Enola Gay, the atomic bomb is believed to have exploded 43 seconds after its release from the aircraft. The "law of motion," another junior high school science topic, states that an object takes the same amount of time to fall, whether dropping straight down or along a parabolic path.

Therefore, if we can identify the location of the Enola Gay 43 seconds before the atomic bomb exploded, that should be the point of release. This can be calculated backward from its velocity. Then, if the plane's direction can be confirmed, the location can be pinpointed on a map.

Mr. Nagata makes some assumptions for the purpose of his teaching methods. One assumption is based on the average speed of the Enola Gay, a calculation based on the distance from Tinian Island, where the Enola Gay took off, and its flight time. As a result of this calculation, he speculates that the point of release was "above Fuchu town" (next to Hiroshima).

Is this conjecture correct? I next met with Yozo Kudo, 58, professor at Tokuyama College of Technology. Prof. Kudo has edited and translated documents from the U.S. military into such books as "The Whole Story of the Atomic Bombings" and "Report on the Atomic Bombings." I asked him to calculate the bomb's point of release based on precise data.

First, Prof. Kudo tried to confirm the speed of the Enola Gay. According to an order issued by the commander of the U.S. Air Force on August 2, 1945, the speed of the Enola Gay for its mission was noted at 200 miles per hour (about 322 km/h). However, the final report produced after the bombing doesn't make mention of the airplane's speed. Although the book "Ruin from the Air," by Gordon Thomas, also suggests the speed was 200 mph, a book by Joseph L. Marx, called "Seven Hours to Zero" pegs the velocity at 285 mph.

Based on this information, Prof. Kudo believes the correct velocity to be 200 mph (about 322km/h). Other B-29 bombers flew at an average speed of 330 km/h, he added, so it is natural to think that the plane carrying the atomic bomb flew at the same speed, as it had been ordered.

As a result, the Enola Gay was flying at a speed of 89.4 meters per second, which means it was located 3845 meters short of the hypocenter 43 seconds before the explosion.

Next, Prof. Kudo considered the direction of the flight. The navigator of the Enola Gay, Theodore Van Kirk, recorded the latitude and longitude in the flight log at the point of attack. This spot was above the city of Mihara, as the original order for the mission had instructed. Prof. Kudo explained that the plane's altitude would be kept stable from that point, in preparation for an accurate drop.

The two books mentioned earlier, their contents based on statements from the crew, note that the Enola Gay shifted its direction southward by 5 degrees to keep the plane on course. This means that the aircraft, when viewed from the hypocenter, had been approaching from the east and bearing northerly by 5 degrees.

I looked for the point on a map and found it located about 100 meters south-southwest of the Yaga train station in the eastern part of the city. Prof. Kudo added that it may be thought the bomb's blast had an impact on the Enola Gay, but any effect was relatively minor. He is convinced the atomic bomb was released near this point. (Keisuke Yoshihara, Staff Writer)