The QT-2 test period in Vietnam in the early months of 1968 was the first use of stealth or low-detection technology in combat and was one of the first operational deployments of night-vision devices aboard aircraft. Night after night, the QT-2 crews peered into the Viet Cong world without the Viet Cong knowing it. Through their Starlight Scopes, the backseat observers saw—in crude, two-tone green and black—heavily loaded sampans traveling on darkened waterways, truck convoys bumping along on unpaved roads, and thousands of campfires twinkling beneath the jungle canopy. They saw VC sappers—demolition teams—with explosives climbing on a bridge along a major highway and onto ocean-going junks on a southern delta river. The observers radioed reports to the U.S. Military Assistance Command, Vietnam, but at that time MACV, for the most part, couldn’t respond. The U.S. military simply didn’t have the capability to fight at night.
But the potential was clear enough to James McMillan, science advisor to General William Westmoreland, the commander of U.S. forces in Vietnam. McMillan summoned Les Horn to Saigon and, giving him almost no time to prepare, told him to brief Westmoreland on the project. When Horn walked into the briefing room, “it was like a Time magazine centerfold,” he remembers, with not only Westmoreland but the U.S. ambassador, the chairman of the Joint Chiefs of Staff, and others. McMillan introduced Horn as the project officer for what he felt was his most significant science achievement in Vietnam.
Horn started his briefing, knees shaking, with a grease pencil and a board. Before the briefing was over, Westmoreland was standing with him at the board, sketching surveillance missions that he wanted to run.
The prototype quiet spyplane had passed its test, and now it was time to develop its successor. Back in California, Lockheed had already used its own funds to build what it called the Q-Star. A radiator from a Chevrolet Corvette sat in the nose, and the thing was even more peculiar-looking than the QT-2. The radiator cooled an exceptionally quiet marine Wankel rotary engine. When Curtiss-Wright, which owned the rights to the Wankel engine, decided against manufacturing an air-cooled version for aviation, the Q-Star became a footnote. Lockheed agreed to Stanley Hall’s proposal to develop the more conventional aircraft that became the YO-3A. (“Y” indicated pre-production; “O” stood for observation; and the meaning of “A” was unclear, possibly indicating later “B” and “C” models that were hoped for but that never materialized.)
The YO-3A had a 220-horsepower Continental engine mounted in the nose and an ordinary propeller shaft in the traditional location but driven at low rpm by quiet rubber belts. It had retractable landing gear mounted inboard on the wings. The observer sat in the front under a large bubble canopy and the pilot in the back. The engine compartment had several kinds of acoustic insulation and a muffler mounted on the starboard side of the fuselage. It had a brand-new sensor package, including a laser target designator that was not compatible with anything the military services had at the time. But what really set the YO-3A apart from its predecessor was that, at $11 million dollars, the program was big enough to trigger every kind of corporate and military oversight, procurement headache, and interservice backstabbing imaginable. “We could have done better,” says Stanley Hall, nominally in charge of airframe design, in reality a man whose design decisions were overruled by higher-ranking executives. The YO-3As were not only much heavier than the QT-2s (3,700 pounds versus 2,500 pounds) but also a lot noisier, with a quiet cruising altitude of 1,500 instead of 800 feet.
With U.S. forces already starting to withdraw from the war, and funding levels falling, only 11 YO-3As were built. Nine were sent to Vietnam in early 1970. They were flown and maintained by the Army in Hue Phu Bai (where a few Marines flew them too) and Long Thanh North, a big base east of Saigon. The little nocturnal spyplanes, nicknamed Yo-Yos, no longer enjoyed an advocate as high up the command ladder as Westmoreland, who was long gone. There was no effort to see what airborne stealth reconnaissance could achieve if given the right resources. And yet the Yo-Yos did their job well.
Much credit goes to the sensor package, which had leapfrogged several generations of technology from the QT-2’s primitive night vision scopes. Never mind the laser target designator, which didn’t work reliably and was seldom used. Protruding from the fuselage beneath the front seat was an ocular, or eyeball. It was like a periscope but controlled by a joystick, and gimballed, so that the horizon always looked horizontal in the viewer. Equipped with a light amplifier for night vision, along with an infrared viewer that sensed heat, it provided a view as clear as daytime of the nighttime scene below. The infrared viewer moved in tandem with an infrared illuminator, a kind of searchlight mounted in the belly, aft of the other optics.
Mark Kizaric was a YO-3A observer. A few months out of high school and a self-described pimple-faced kid, he became adept at using the ocular and manipulating the joystick. “After a while you’d get in a zone where you didn’t even think of yourself as being up in an aircraft,” he recalls. “You kinda lost contact with the real world. It was more like a video game. You’re just, you know, going along, you’re acquiring targets, noting positions, calling in artillery.
“Most of the time we worked with artillery,” says Kizaric, who is now an engineer in Wisconsin. “One especially strong memory is of a very large sampan moving down a river, 30 to 40 feet in length and riding very low in the water at about three or four o’clock in the morning where nobody’s supposed to be. We directed artillery fire, and though I’ll acknowledge a level of skill on my part, [there was] also an awful lot of luck. I happened to get a direct artillery hit. The sampan had to be loaded from stem to stern with ammunition, because there was a blinding flash that, even outside the ocular, lit up the whole night sky. I lifted my head away and there was this brilliant orange flash. A few seconds later I put my eye back in the ocular and the sampan had literally vanished.”
On other nights and missions, the Yo-Yos worked with the helicopter gunships of the 1st Air Cavalry. “We would go well ahead of the choppers and acquire the targets, because we were silent,” says Kizaric. “We would find, you know, people sitting around campfires, hot truck exhaust, something like that. We could literally see, in some cases, people moving around on the ground. We would note the position, call in the Cobra gunships, and lock onto the target with our ocular and illuminate the target. When people on the ground heard the choppers come in, all the fires go out and they start scrambling. But it was too late then. We had them on the IRI—the infrared illuminator. The gunships had a screen that could also pick up the infrared illuminator, and so they would home in and open fire.