Isegoria

The phenomenally low radar cross section on the Oxcart (proto-SR-71), Annie Jacobsen explains (in Area 51), had to be lowered even further:

In a hangar not far from the radar range, Edward Lovick got to work on a one-eighth-scale model of the Oxcart. In what became known as Project Kempster-Lacroix, Lovick designed a system straight out of Star Trek or James Bond. “Two giant electron guns were to be mounted on either side of the aircraft,” Lovick recalls. Remarkably, the purpose of the guns would be “to shoot out a twenty-five-foot-wide ion cloud of highly charged particles in front of the plane as it flew over denied territory.” That gaseous cloud, Lovick determined, would further absorb radar waves coming up from radar tracking stations on the ground.

Using the small-scale model, the scientists were able to prove the scheme worked, which meant it was time to build a full-scale mock-up of Kempster-Lacroix. Testing the system out on a full-size aircraft, the scientists discovered that the radiation emitted by the electron guns would be too dangerous for the pilots. So a separate team of engineers designed an X-ray shield that the pilots could wear over their pressure suits while flying an Oxcart outfitted with Kempster-Lacroix. When one of the pilots made a test run, he determined that the thickness of the shield was far too cumbersome to wear while trying to fly an airplane at Mach 3. Then, while Lovick was working on a solution, the Air Force changed its mind. The Oxcart’s low observables were low enough, the Pentagon said. Project Kempster-Lacroix was abandoned.

To the pilots of the still-experimental Oxcart, Annie Jacobsen explains (in Area 51), there was nothing scarier than an engine un-start:

To the engineers, there was nothing to explain the cause of it. Flying at a certain pitch, one of the two J-58 engines could inexplicably experience an airflow cutoff and go dead. At that speed, the inlets were swallowing ten thousand cubic feet of air each second. One engineer likened this to the equivalent of two million people inhaling at once; an un-start was like all those people suddenly cut short of air. During the ten seconds it took to correct the airflow problem—one engine dead, the other generating enough power to propel an ocean liner—a violent yawing would occur as the aircraft twisted on a vertical axis. This caused a pilot to get slammed across the cockpit while desperately trying to restart the dead engine. The fear was that the pilot could get knocked unconscious, which would mean the end of the pilot, and the end of the airplane.

[…]

Once, a pilot flying over semirural West Virginia had to restart an engine at thirty thousand feet. The resulting sonic boom shattered a chimney inside a factory on the ground, and two men working there were crushed to death.

[…]

Collins pushed the aircraft through Mach 2.8. In another forty-five seconds he would be out of the danger zone. Nearing eighty-five thousand feet, the inevitable tiny black dots began to appear on the aircraft windshield, sporadic at first, like the first drops of summer rain. Only a few months earlier, scientists at Area 51 had been baffled by those black dots. They worried it was some kind of high-atmosphere corrosion until the mystery was solved in the lab. It turned out the black spots were dead bugs that were cycling around in the upper atmosphere, blasted into the jet stream by the world’s two superpowers’ rally of thermonuclear bombs. The bugs were killed in the bombs’ blasts and sent aloft to ninety thousand feet in the ensuing mushroom clouds where they gained orbit.

[…]

In a critical instant, the airplane banged and yawed so dramatically it was as if the airplane’s tail were trying to catch its nose. Collins’s body was flung forward in his harness. His plastic flight helmet crashed against the cockpit glass, denting the helmet and nearly knocking him unconscious. As the airplane slid across the atmosphere, Collins steeled himself and restarted the engine. The aircraft’s second engine kicked back into motion almost as quickly as it had stopped.

[…]

A hand-cranked calculator and a metal slide rule sat on Rich’s desk. Park set his flight helmet down—it had its own crack, similar to Collins’s—and pointed to it. “Fix it,” Park said. “And I mean the un-start problem, not my helmet. Time to suit up, Ben. Time for you to see how it feels.” The pilots figured that the only way to get Ben Rich to understand just how unacceptable this un-start business was would be to have Rich experience the nightmare scenario himself, and there just happened to be a two-seater version of the Oxcart on base. The Air Force was currently testing its drone-carrying version of the Oxcart, the M-21/D-21, in the skies over Groom Lake, and the pilots had seen the two-seater going in and out of the hangar all week. Park told Ben Rich the time had come for him to take a Mach 3 ride.

In a burst of what he would later describe as “a crazy moment of weakness,” Ben Rich agreed. Rich was a self-described Jewish nerd. Totally unathletic, he was a kid who never made the high school baseball team. Before joining Skunk Works, Ben Rich had only one claim to fame: being awarded a patent for designing a nickel-chromium heating system that prevented a pilot’s penis from freezing to his urine elimination pipe. He was a design wizard, not an airplane cowboy. He’d never come close to flying supersonic before, and he had absolutely no desire to go that fast. But he was chief engineer for Skunk Works, so fixing the un-start problem was his job. “I’ll do it,” Ben Rich said.

[…]

Rich passed the physical and a few early stress tests but when he got to the pressure-chamber test—the one that simulated ejection at fifty thousand feet—things did not go as the engineer had planned. The moment the chamber door closed behind Ben Rich, he panicked. “I was sucking oxygen like a marathon runner and screaming, ‘Get me out of here!’” Rich later recalled. Without ever getting close to simulating what it was like to fly at Mach 3, let alone experiencing an un-start at that speed, Ben Rich admitted in his memoir that he had still nearly dropped dead from fright.

But the point was made. Rich dedicated all his efforts to fixing the un-start problem.

[…]

Rich invented an electronic control that made sure that when one engine experienced an un-start, the second engine dropped its power as well. The control switch would then restart both engines at the same time. After the new fix, pilots were notified of the un-start by a loud buzzing noise in the cockpit. And as far as nearly getting knocked unconscious at 2,000 miles per hour, Oxcart pilots could cross that off their lists of concerns.