Skunk Works

The CIA code-named the project Rainbow. The orders came directly from the Oval Office and had the highest priority. Every one of Kelly’s engineers and designers was put to work. The object: significantly lower the U-2’s radar signature or face a presidential cancellation of the entire program. These orders arrived just before the new year in 1956, after only seven or eight overflights of the Soviet Union. The Russians were using diplomatic channels to scream at us. They were too embarrassed by their own ineptitude in being able to stop the overflights to make their threats public, but that did not make these threats less ominous.

So the heat was on to find ways to reduce the airplane’s radar signature from approximately that of a Fifth Avenue bus to the size of a two-door coupe. But the U-2’s big tail, wings, and large inlets designed for its lift and thrust got in the way, acting like a circus spotlight on hostile radar scopes. Kelly flew to Cambridge, Massachusetts, seeking advice from a high-powered scientific group doing research on antiradar technology. He brought back with him two of their best radar experts, Dr. Frank Rogers and Ed Purcell, to help us brainstorm. I was involved analyzing various composites and paints that might be tried to absorb radar energy without adding too much weight to the airplane. The U-2 was painted a dull black to prevent it from glinting in the sun. We wanted to make it as difficult as possible to achieve human detection from the ground or from below in an interceptor trying to reach it. And we began experimenting with chromic paint that changed from different shades of blue to black at different temperatures like a chameleon. But paint added more weight than deception, as did the idea of painting the U-2 with polka dots to break up the silhouette against the sky. As for fooling radar, Rogers and Purcell suggested a radical fix: stringing piano wire of various dipole lengths along the entire fuselage in the hope of scattering as much radar energy in as many frequencies as possible in every direction. The wires made the U-2 draggy and we lost seven thousand feet in altitude.

The next thing we tried was something called a Salisbury screen, a metallic grid applied to the airplane’s undercarriage in the hope of deflecting incoming radar beams, but it worked only at some frequencies and altitudes and not at others.

Kelly thought it was more practical to try special iron ferrite paints that would absorb a radar ping rather than bounce it back to the sender. The paints were moderately effective but inhibited heat dissipation through the airframe’s outer skin and we experienced overheating engine problems. But the paint lowered the radar cross section by one order of magnitude, so we decided to give it a try. We called these specially painted airplanes “dirty birds” and shipped the first one out for flight testing in April 1957. Our test pilot, Bob Sieker, took the U-2 up to over seventy thousand feet and suddenly radioed that he was experiencing rapid airframe heat buildup. Moments later his engine blew out and the faceplate blew off Bob’s oxygen mask as his pressure suit instantly inflated. The U-2 dove straight down and crashed. It took us three days to locate the wreckage and Bob’s body. An autopsy revealed that above seventy thousand feet he had suffered acute hypoxia and lost consciousness in only ten seconds. The culprit that killed him was a defective faceplate clasp that cost fifty cents.

The CIA was so desperate to buy time for these Soviet overflights that Bissell got Kelly to sequester four of our test flight engineers and have them write a bogus flight manual for a U-2 twice as heavy as ours and with a maximum altitude of only fifty thousand feet that carried only scientific weather gear in its bay. The manual included phony instrument panel photos with altered markings for speed, altitude, and load factor limits. Four copies were produced and then artificially aged with grease, coffee stains, and cigarette burns. How or if the agency got them into Soviet hands only Mr. B knew, and he never told.