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Published on 07/01/1996 All articles from this issue

The two-hat letter and a question of visibility

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By Donald Kelly

In World War II, my first assignment in the Navy involved testing various aircraft paint schemes at Patuxent River Naval Air Test Center, on Chesapeake Bay. There a small group of camouflage people in the Tactical Test Unit had been measuring visual detection thresholds for small aircraft models, a few inches long, hanging from wires against a clear sky background. But the results were invariably the same, no matter what paint scheme was used, because they were all thresholds for resolving a small dark blob against a bright background.

As a recent graduate in optical engineering, I recognized this as a problem in atmospheric optics. When a full-scale airplane disappears in the distance, it is usually obscured by haze in the atmosphere, even on a clear day when the pilot is not trying to avoid detection. Now that is partially a contrast threshold, not simply a resolution threshold, and it occurs much closer to the observer than the scaled distance calculated from the model planes. As I tried vainly to explain to my new colleagues, they had not scaled down the atmosphere.

There were three other reserve officers in the Aircraft Camouflage Section. All well-meaning fellows, none of them could understand the folly of what they were doing. The skipper of this motley crew was a curator of mummies from the Boston Museum. Worse, he was bucking for promotion to lieutenant commander, and he was determined not to rock the boat. We were following orders, he said, and it would be a breach of Naval discipline to change our procedures in any way.

But before leaving Patuxent River, I was able to rectify this fiasco. My superiors were being mustered out, and I would soon be left in command of Camouflage at Patuxent. My alma mater provided me with an ingenious little device that did scale down the atmosphere, so I could do some experiments that proved the point, using the same camouflaged model planes but this time at realistic distances. I happily wrote up the results, and soon found something to do with them.

I was being transferred to the Camouflage Section at BuAer in Washington, where my new superior was a pilot recently back from the Pacific, who just happened to have an MS in engineering from Cal Tech. He was much more understanding. With his blessing, I became the cognizant officer at BuAer over the Camouflage Section at Patuxent River until it was finally de-commissioned. During that brief period, I held two desks in the Navy - my old one at Patuxent, and my new one in BuAer. At BuAer, I wrote up orders for Patuxent to carry out the experiments that I had just done. Then I hurried down to Patuxent to receive the orders and convert our experimental results into an official report to BuAer.

Most military communications are not signed by the person who writes them but by a higher-ranking officer. In this case, any official communication between BuAer and the Naval Air Test Center, had to go over the desk of the flag officer in command at each end. So there was plenty of time for me to get back to BuAer before the report of the final Patuxent experiments arrived at my new desk. I read it with great satisfaction. It followed my orders exactly and was, I thought, an excellent job. The fellow deserved a commendation, so I wrote him one, and sent it out through channels.

I had to make one more trip to Patuxent to prepare for the move to Washington. While cleaning out my quarters, I was suddenly summoned to report to the commander of the Tactical Test Unit, a regular Navy captain whom I had never met. I saluted him with some trepidation, but he was all smiles. He just wanted to shake my hand and make sure I had received a copy of the commendation. "In all my time on this base," he said in a confidential tone, "this is the only commendation we have ever received from BuAer! Well done, Ensign!"

Back in civilian life a few years later, I received a letter from the OEG, an MIT think-tank at the Navy Department, asking if I could help them locate the Patuxent River detection data. I directed my correspondent to the scaled-atmosphere experiments, adding that to the best of my knowledge, all the rest of the data had been lost, and that I fervently hoped those data would stay lost, because if they were ever found, the science of visibility would be set back 50 years. I never heard from him again.

Donald Kelly isa Los Altos Hills resident.