On January 31, 1968, the Viet Cong launched attacks in cities throughout South Vietnam — the Tet Offensive had begun. At home, protest rallies grew and became both more violent and more pro-North Vietnam. On March 31, President Johnson halted all bombing north of the nineteenth parallel. Peace talks opened in Paris on May 13, and on November 1, Johnson ordered a halt to all bombing of North Vietnam.[260]
The 147Hs were also continuing overflights of Communist China, now engulfed by the madness of Mao Tse-tung's "Great Proletariat Cultural Revolution."[261] On April 30, 1967, the shooting down of a drone over south China was announced.[262] Another announcement followed on June 12.[263] A total of fourteen drones had been shot down by the end of 1967. A fifth Nationalist Chinese U-2 was also shot down on September 9, 1967. The pilot, Capt. Tom Hwang Lung Pei, was killed when an SA-2 hit his plane.[264] In early 1968, it was decided to end the Nationalist Chinese U-2 overflights, due to the risk. From now on, the 147H drones would carry the burden of watching China.
The new role had a cost — on January 20, 1968, the Chinese shot down 147H-25. The Peking Review's announcement reflected the political madness sweeping China: "The Air Force of the heroic Chinese People's Liberation Army, which is boundlessly loyal to Chairman Mao Tse-tung's thought and Chairman Mao's proletarian revolutionary line, shot down a U.S. imperialist pilotless high-altitude military reconnaissance plane when it intruded into China's air space over southwest China for reconnaissance and provocation." In March 1968, a "bad streak" of three drone losses over China brought to eighteen the number of drones lost on China overflights since November 1964. Despite this, the 147H's loss rate was below that of the 147B and G drones.[265]
THE DEFINITIVE DRONE — THE 147S BUFFALO HUNTER
December 1967 saw the debut of the first of a family of low-altitude drones, a series that would form the backbone of the final years of 147 operations. The 147J was not the ideal low-altitude drone. Its long, flexible wings, originally built for the high-altitude 147G, were somewhat unstable at low altitude and prevented the 147J from making sharp turns. The 147NPs and NQs were a quick, short-term effort.
There was a need for a low-cost drone specifically designed for the low-altitude mission. Ryan was told that if they could produce a cheap drone to replace the 147J, the production run would amount to several hundred, compared to only thirty to forty of the other models.
In building the new drone, Ryan went back to the basic Firebee design.
The Firebee's 13-foot wing was used; this was much cheaper than the long wing of the G and J models. The fuselage was 29 feet long and carried a redesigned camera system. Rather than two cameras, as on the 147J, the new drone had a single camera. This provided an 80 percent increase in coverage. The contract for the new 147S drone was issued in December 1966. Unit cost was about $160,000—40 percent less than that of the G and J drones.[266]
It would take a year to get the 147S into operation. Five of the last 147Gs were modified to test the new "poly-profile" low-altitude control system. In the first test of the system, the drone flew into the water. There was a lag in the system, with corrections coming too late. It took six weeks to develop a fix for the problem. It was known as the "Polly Get Well Kit."
When the 147S test flights were completed, there were a number of proposals for modifications which would give it additional capabilities. These included antiflutter kits, different yaw rate gyros, multiple altitude settings, radar altimeters, and a digital programmer. It was decided to group the changes in production blocks. All the drones in a specific block would have identical configurations.
The first such block was the 147SA. A total of forty were produced. The first operational mission was made in December 1967. The drone's camera could produce photos with a one-foot resolution along a sixty-mile-long strip of North Vietnam. In some cases, objects as small as six inches could be identified. On one mission, a stack of truck tires in a storage yard was photographed. The trademark could be read.
Most of the 147SA missions were directed at the main bridges around Hanoi. These were under repair, and it was necessary to have regular coverage. Other targets were supply lines and SAM sites. In some cases, winds or navigation problems would cause the drone to go off the track, but the targets of opportunity picked up would often be more valuable.
The early 147SA missions were very successful, and, in March 1968, a second block of forty drones was ordered. The 147SB carried the multiple altitude control system (MACS). The 147SB could be programmed to fly at three different altitude settings between 1,000 and 20,000 feet. It could also vary between the three settings throughout the mission, making it much less predictable. The drone was also equipped with new yaw gyros that allowed tighter, more precise turns.
The first 147SB missions were flown in March 1968, overlapping with the 147SAs. One early mission was flown by a pair of drones over Haiphong Harbor. The Soviets claimed one of their freighters had been tor-pedoed by the United States as it entered the harbor. The drone unit was ordered to photograph the ship to see if it had been damaged. The drones' flight paths were to cross over the ship. The two drones flew as programmed and returned with photos looking directly into the cargo hold.
They showed no damage at all. The North Vietnamese, however, caused some damage when they opened fire at the low-flying drones. Shooting at a nearly flat trajectory, the shells hit the ground throughout the harbor area.
The 147S drones were the source of a number of "war stories." None matched the adventure of 147SB-12 on October 6, 1968. After launch, the MACS had a problem and rather than flying at an altitude of 1,500 feet, the drone flew at 150 feet above the ground. Its programmed flight path took it under a line of high-tension power lines. The photo showed the tower looming above the drone, while on the ground, people were looking upward at the low-flying plane. The unit commander posted the photo on the bulletin board with a note saying, "The FAA frowns on this bullshit!"[267]
Such achievements were not without cost. With the partial bombing halt on March 31, the drones became a prime target. Flying at 1,000 to 1,200 feet, they were taking heavy losses. On April 21, SA-17 was lost over Haiphong.[268] On June 8, a drone was reported shot down over Hanoi.[269]
A change in profile was necessary — the drones were set to fly at 500 feet and 500 knots. This put them below the m i n i m u m altitude of heavy antiaircraft guns, while the high speed made them difficult to hit with light antiaircraft guns or small arms.[270] Still, by late 1968, the North Vietnamese had shot down a total of about forty of the drones.[271]
The North Vietnamese also sought to end the drone flights through political means. When the Paris Peace Talks opened, the North Vietnamese demanded an end to all reconnaissance flights. This was described as the first order of business: the halt must be "without delay" and "definite and unconditional," and continuation of the talks was dependant on U.S. acceptance of the demand.[272] This effort also proved ineffective. United States reconnaissance flights continued to monitor North Vietnamese activities.
These reconnaissance photos showed that, within two weeks of the bombing halt, the North Vietnamese had repaired all the bombed-out bridges between the seventeenth and nineteenth parallels. Roads had also been made passable, and troop and truck traffic had quadrupled to some four hundred trucks per day.[273]
The next version of the 147S family made its debut in November 1968.
This was the 147SRE night reconnaissance drone. They were equipped with a near infrared strobe. In flight, this was visible as a small red light; it was hard to see unless someone looked directly at it, making the drone much harder to track than the white-light strobe on the NRE. The film was geared to near infrared, and the camera had a filter to cut down the effects of haze. A doppler navigation system also provided better accuracy than the NRE.
The first flight, by 147SRE-1, was made on November 7, 1968. A total of five flights were made in November and six more in December. Missions were flown in the predawn hours, when activities w
ere just starting. When compared to photos taken later in the day, this would give an indication of activities.
The December 19 flight of SRE-2 was an adventure. As it flew over a SAM site, it was fired on. The camera photographed the SAM overtaking the drone, then exploding behind it as the SAM hit the ground. A second SAM was launched, which passed so close the photo was burned out by the exhaust flame. The flight was intended to cover the Haiphong docks and seaplane base, then turn west to cover an airfield near Hanoi. The doppler system was not set correctly, however, and the turns were coming late. This caused the drone to fly to an area northwest of Haiphong, where it missed colliding with a ridgeline seven times. The photos showed it only ten or twenty feet above the trees. The final 147SRE flight was made in October 1969.
Although the SREs were successful, less use was made of the system than was possible. The photo interpreters were not trained in analyzing the near infrared images. Many times targets were missed.[274]
A total of 340 drone missions were launched in 1968. Of these, 205 were 147S drones, while only 67 were 147H high-altitude flights. Clearly, there was a shift in operations. The original concept of high-altitude, covert reconnaissance, similar to that of the CIA U-2 overflights, had been replaced by the much simpler low-altitude mission.
In January 1969, the 147SC was introduced. The SC drones had a cross-correlation doppler radar and a digital programmer to improve navigation accuracy. Of the total of 437 launches made in 1969, 307 were SC drones, known as "Buffalo Hunters." They provided photos with a three-to-five-inch resolution and were used to provide technical intelligence. In contrast to the huge numbers of SC drones, there were only twenty-one high-altitude 147H missions during 1969. These were conducted between January and June; it would be seven months before another was flown.[275]
The drone program did suffer losses, but throughout the war the North Vietnamese grossly inflated the American losses. On April 19, 1969, they reported shooting down a drone, which they claimed was the 3,278th U.S. aircraft downed over the north.[276] In fact this total was more than twice the true number. The actual drone loss rate in 1969 was 24 percent. Even if hit, the drones often survived. During H-58's seven flights during 1969, it was damaged twice. SC-75, dubbed "Myassis Dragon," was hit seven times by shell fragments during its eighth mission. After recovery, SC-75 was "awarded" a Purple Heart. (SC-75 was finally "killed in action" on its tenth mission.)[277]
BELFRY EXPRESS
Up to this point, the drones had been solely an air force operation. The navy had access to the information, but thought it was not timely enough.
Now the navy wanted to test the idea of drones being launched from ships.
This would give the task force commander the ability to cover targets immediately. A contract was issued to modify several SC drones for surface launch. These were the 147SKs; they used the SC's 29-foot fuselage, but with 15-foot wings (two feet longer than the SC's).
Test launches were done from Point Mugu and from the U.S.S. Bennington before deployment off Vietnam. The drone got its initial boost from a rocket, which would burn out and separate. An E-2A aircraft would guide the flight to the initial point, where the drone's own system would take over and fly the programmed mission. After it was completed, a midair recovery would be made. The program was code-named "Belfry Express."
For the operational missions, three 147SK drones were loaded aboard the U.S.S. Ranger. The first flight was made on November 23, 1969, to cover North Vietnam's Highway 1, which ran parallel to the coast a few miles inland. SK-5 was launched successfully, but the carrier was two miles out of position. This meant the ground track was shifted, and the drone photographed an area two miles seaward of Highway 1.
A second mission was flown on November 27, which followed the planned route. The third Belfry Express mission was made on November 30. This time, a midair recovery was made by an air force helicopter. After landing on the Ranger's deck, the pilot climbed out with a large American flag and announced, "I claim this island for the United States Air Force!"
By February 10, 1970, fifteen Belfry Express missions had been flown.
SK-5 was launched on mission sixteen and ran into problems. The tracking beacon could not be picked up, and the drone was lost. When the drone ran out of fuel, a radio signal to deploy the parachute was transmitted. A helicopter was sent to its estimated position, but nothing was found.
Several days later, the Chinese announced they had "shot down" SK-5 over Hainan Island. This was the 20th drone to be lost over China. A newspaper report said, "A broadcast from Canton describing the downing of the plane said that the craft 'cunningly' changed altitude as it veered over Hainan but 'could never escape the eyes of our radar operators.' Chinese Navy men were said to have 'shot down' this U.S. pirate plane at once 'while cherishing infinite loyalty to our great leader Chairman Mao and harboring bitter hatred for the U.S. aggressors.'"
A total of fifteen more Belfry Express missions were flown after SK-5's capture. The three missions of April 18, 22, and 27, 1970, were particularly effective, providing photos of SAM and antiaircraft gun sites at Vinh and Than Hoa, as well as railroads, bridges, pipelines, truck parks, storage yards, and anchorage areas. The only disappointment was the loss of SK-3 on April 24. The mission was successfully flown, but the drag and main parachutes failed to deploy.
The final flight, by SK-10, was made on May 10, 1970. After a near perfect mission, the main parachute failed to open, and the drone was destroyed. The problem was later traced to salt water contamination of the parachute actuation circuit cable. On this note, Belfry Express, and the navy experience with drone reconnaissance, ended.[278]
LAST OF THE BREED — THE 147T
Although the 147S family made up the bulk of flights in 1969, the year also saw introduction of the final high-altitude drone — the 147T. It had been ordered in early 1967 as successor to the 147H. It used the basic 147H airframe and camera but had a new engine that increased the maximum altitude to 75,000 feet. The 147T also carried the Rivet Bouncer SA-2 jammer and the radar-absorbing inlet coating.
The first 147T missions were flown in April and May 1969, followed by a second series in October and November 1969. One of the new drones, T-17, was shot down over China on October 28. Further 147T missions were flown during February-May 1970, then again in September 1970.
With this, the program ended after only twenty-eight missions over two years. The same pattern was true for the 147Gs. There were only nineteen 147G flights in 1970, and a mere nine in 1971. In both years, the 147Gs were flown between March and June. This brought the era of high-altitude drone photo reconnaissance to a close. The 147T would find success in another mission.
On April 18, 1969, a navy EC-121 ELINT aircraft was shot down by North Korean MiGs over international waters. All thirty-one crewmen were killed.
Lieutenant Colonel Andy Corra, head of unmanned reconnaissance systems, learned of the incident as he left his hotel for a meeting at Ryan Aeronautical to review the 147T program. When he arrived at the plant, he suggested using the 147T as an ELINT drone. It would carry receivers that would pick up radar and radio transmissions. The data would then be relayed from the drone to a ground station. Operators on the ground would control its operations.
The first briefing was ready a week after the EC-121 was lost. Four 147T drones were modified into a TE configuration. The first test flight was made on November 25, 1969. They were then sent to Osan, South Korea, for operational testing. It was a schedule that many in the National Security Agency had said was physically impossible to meet.
The first 147TE mission was flown on February 15, 1970, beginning a two-month operational test program. The drone was equipped with ten receivers for radio traffic. A ball-shaped radome on the drone's tail relayed the transmissions. Each receiver was individually controlled from a ground station. The 147TE could fly a preprogrammed mission or be controlled by the DC-130 launch aircraft. In some cases, it would have to fly a very tight "race trac
k" pattern to remain within the signal beam. Following the initial 147TE missions, a contract was issued for fifteen production 147TE drones, in a program code-named "Combat Dawn." The first flight of the production TEs was made on October 10, 1970.
Unlike the other drones, the 147TEs remained at least fifty nautical miles offshore. The ELINT drones flew two types of missions — over the Yellow Sea between North Korea and China, and along the Demilitarized Zone between North and South Korea. Several times, MiGs were sent out after the drones. When MiGs were detected, the drone was maneuvered to avoid the fighters. None were lost to enemy action. Late in the TE program, external tanks were added to the drone, which increased the flight time from five hours to nearly eight. The 147TEs provided about ten thousand hours of intelligence data per year. A total of 268 147TE missions were flown up until the replacement of the drone in June 1973.
The replacement was an improved version, the 147TF. They were fitted with the external tanks and ELINT equipment that could pick up either radio or radar transmissions. The 147TF was introduced in February 1973 and would make 216 flights over the next two years, until the end of the drone program.[279]
SON TAY
The most significant of the 276 147SC missions flown in 1970, out of a total of 365 drone flights, was a "package" of seven. Their target was a small, isolated, walled compound twenty-three miles west of Hanoi. It stood on the bank of the Song Con River, outside the provincial capital of Son Tay. It was a POW camp, and the United States was planning to raid it. The camp was identified in May 1970. Comparison of old and new reconnaissance photos showed a guard tower and new wall had been added. It was also noticed that some uniforms had been spread out on the ground to spell out "SAR" — search and rescue. In one corner of the compound the letter K had been stomped in the ground — the code letter for "come get us." The POWs were calling for a rescue mission.[280]
Dark Eagles: A History of the Top Secret U.S. Aircraft Page 15