That New Black Magic
In the early years of the cold war, enter Kelly Johnson and an clean sheet of paper--long enough to accommodate an 80-foot wingspan.
- By William E. Burrows
- Air & Space magazine, January 1999
(Page 3 of 4)
Then there was the oil problem. Because the atmospheric pressure at altitude was so low, oil leaked through the J-57's seals and got into the U-2's air conditioning and de-fogging systems. Engineers calculated that during an operational mission, 64 quarts of oil--the maximum capacity of the system--might be lost. The de-fogging ducts sprayed the windshield with hot air from the engine's compressor, and during long flights a gradually thickening coat of oil would form on the glass. This was solved by providing pilots with long sticks with diaper cloth attached to the ends so they could wipe the windshields clean. Someone even got the idea of welding a small metal box on the de-fog line and stuffing it with Kotex to absorb the oil. But the hot air was under so much pressure that it bent the box out of shape, says Lockheed's Bob Murphy, who was involved in many aspects of the U-2 and SR-71 programs. The problem ended only when the P-31 engine, which required less oil and was optimized for high altitude, replaced the model 37 in 1956.
Another worry was jet fuel: The standard JP-4 and JP-5 would boil away at high altitude. General James Doolittle, an executive with Shell Oil, had been a technical advisor to the reconnaissance community, and he persuaded Shell to develop a new jet fuel, designated JP-7, that had very low volatility. Production of JP-7 required most of the stocks of the petroleum products the company used to manufacture insect sprays, and although few Americans knew why, there was a nationwide shortage of bug spray in 1955.
In the near vacuum of the upper atmosphere, pilots also required special protection so that their body fluids would not bubble and boil. To this end, the David Clark Company of Worcester, Massachusetts, devised a partial-pressure suit, which was the first of its kind for keeping pilots alive in near-space conditions. This even led to the first specialized food and water provisions. Pilots could push a tube through a little hole in the face mask and suck on sweetened water or cheese- and bacon-flavored food mixtures squeezed from soft containers.
Undoubtedly the most daunting problem faced by U-2 pilots was the infamous "coffin corner," the terribly tiny margin between Mach-shock and stall buffet. At altitudes above 65,000 feet, the first U-2s had an interval of only six knots (7 mph) indicated airspeed between the onset of Mach buffet and a stall. In other words, the difference between the U-2's slowest flying speed and its fastest was only six knots. The margin was so narrow that Lockheed test pilots reported that in a bank, a U-2's inner wing could be stalled while its outer one was buffeting wildly from excess speed.
And as Ben R. Rich, the engineer who succeeded Johnson as head of the Skunk Works, said, "The shuddering felt the same whether it was because of flying too fast or too slow, so a pilot had to keep totally alert while making corrections." Once a U-2 pilot reached 70,000 feet and 400 knots true airspeed, he tried very hard to stay right there.
"The original U-2 was a difficult airplane to fly," says Garfield J. Thomas, vice president of Reconnaissance Systems at what is now Lockheed Martin. "It was a lot of work." Knowing that, the inventors of the revolutionary camera designed it to be automatic. "The pilot really had very little to do with the camera," adds Thomas. "The camera was usually pre-programmed and set up. When he reached a certain area, in the old days, he'd just throw a switch."
The camera itself was the result of a remarkable collaborative effort between Edwin "Din" Land, inventor of the Polaroid Land Camera, and James G. Baker, a Harvard-educated astrophysicist whose interest in optics went back to the 1930s. Land, a longtime member of the reconnaissance community's inner circle, led a group of presidential science advisors known as Project 3. In the U-2, he saw an airplane that could carry a camera good enough to count Soviet bombers and resolve the controversial "bomber gap," and it was Land who introduced the concept to President Dwight Eisenhower. Baker designed the U-2's camera, which carried a mile of specially developed, ultra-thin Eastman Kodak film. The film itself weighed around 300 pounds and had to be spooled on tandem nine-inch-wide rolls that fed in opposite directions on parallel tracks to maintain the airplane's center of gravity (see "Captured on Film," above).
The so-called Type B camera was fabricated by Hycon Corporation in California. Fitted into the Q-bay, which was pressurized to 0.25 atmosphere (one atmosphere is a unit equal to the pressure of the air at sea level: 14.7 pounds per square inch), it was mounted on a hatch that actually formed a section of the skin of the airplane. The U-2 (and its supersonic successors, the A-12 and SR-71) would also come with noses that could be replaced with others carrying different sensors, the way lenses are changed on cameras.