Progress was painfully slow during the summer and fall of 1965; the D-21, its launch mode, the complexity of the D-21's systems, the aerodynamic combination of the two aircraft, and the technical problems of operating a high-speed drone all proved difficult. A new test range was needed, as the D-21/M-21 could not accelerate sufficiently within the range being used for the early tests. This was followed by performance problems; the weight and drag of the D-21 cut into the M-21's speed and range. The D-21/M-21 also showed poor transonic acceleration, particularly on hot days, Several attempts were made to fly to Point Mugu for launch practice, but the plane could not make the range. More powerful engines were fitted to the M-21s, along with a new inlet control system, but the problems persisted.
The old uncertainties with the launch profile also reappeared. The instrumentation system's strain gauges could not measure the launch forces, due to the heat of Mach 3-plus flight. Johnson was unwilling to commit to a launch until he was sure the separation maneuver was understood. The program was effectively stalled. The first batch of D-21 drones had been completed, but Lockheed was yet to launch a single free flight, and Johnson was unwilling to recommend building any more D-21s until it had been proven in flight.
A final problem facing the D-21 program was how to separate the intake and exhaust covers. Fragments could enter the ramjet and strike the M-21.
These fears were justified on the first, and only, attempt to separate the covers. The pieces tore up the chines of 503, causing major damage.
It was decided to leave the covers off. Ironically, this also provided the solution to the drag problem. With the covers off, the ramjet could act as a third engine for the M-21 during the acceleration to launch speed. It would be started at Mach 1.24. Just before launch, fuel from the M-21's tanks would be transferred to top off the D-21, replacing that used during the run-up to the launch point.
By late January 1966, more than a year after the first captive flight, everything seemed ready. The launch forces were understood, the ramjet operations and hatch recovery had been proven, and the launch maneuver had been practiced. Although the Minneapolis-Honeywell guidance system was not ready, this would not affect the test flights.[310] As with the other A-12s, Article 135 was painted all black with white markings. The D-21s were also painted all black. (Article 134 would remain in the silver and black finish.)
D-21 LAUNCHES
The first D-21 launch was made on March 5, 1966. William Park was the pilot, while Keith Beswick acted as LCO. On this first mission, D-21 Article 503 had only a partial load of fuel. After takeoff, the combination headed east. Over Texas, the M-21 rendezvoused with a KC-135 tanker, refueled, and started the run to the launch point. This began over the town of Dalhart, Texas, on a direct course toward Point Mugu. The D-21/M-21 accelerated slowly at first as it crossed New Mexico. When the proper speed was reached, the ramjet was started. The combination began to pick up speed.[311]
As the D-21/M-21 neared the launch point, it was flying at a speed of Mach 3.2 and altitude of 72,000 feet. Once the checkout was completed and the tanks of the D-21 were topped off, Park began a slight climb, followed by a pushover into a slight dive, holding 0.9 gs on the M-21's precise g-meter. Once Park was satisfied with the profile, he gave clearance to launch.
Beswick then pressed the release button.[312] Through the periscope, Beswick could see the D-21 rising off the pylon.
There was a small puff of vaporized fuel as it separated. Article 503 held steady as it rose away from the M-21. Then, it stopped and seemed to hang perhaps twenty feet above the back of the M-21. For two or three seconds, the D-21 flew in formation with the M-21. Beswick said later at the debrief-ing that it seemed to have flown in formation for "two hours." The onboard camera had recorded the sight. Finally, it passed out of the view of the periscope. Article 503 flew for 120 nautical miles before it ran out of fuel.[313]
Despite the successful flight, CIA and air force interest remained limited.
This placed a burden on Lockheed, as the D-21 program was strapped for money. Johnson had discussions with air force officials and offered, if necessary, to have Lockheed crews launch the early operational missions. He was also looking at a new launch profile — attaching a rocket booster to the D-21 and launching the assembly from a B-52. Despite the successful launch, he was still concerned about the risks of the M-21 profile.
A second D-21 launch was made on April 27. This time Torick was the LCO. Article 506 flew for 1,200 nautical miles, holding its course within a half nautical mile throughout the flight. The peak speed was Mach 3.3, while an altitude of 90,000 feet was reached. The flight ended when a hydraulic pump burned out. Subsequent investigation indicated it had been run unpressurized several times during ground tests, which damaged it.
The two successful launches sparked renewed interest, and an order for a second batch of fifteen D-21s was issued on April 29. In May, Johnson formally proposed the new launch profile. Using a B-52H as the launch aircraft, he told the air force, would improve safety, cut costs, and extend the deployment range over the short-range M-21.
The third D-21 launch was made by Park and Beswick on June 16. Article 505 flew 1,550 nautical miles and made eight programmed turns to photograph the Channel Islands, San Clemente Island, and Santa Catalina.
The flight was perfect until hatch separation. Due to an electrical problem, this did not occur.[314]
The fourth D-21 free flight was set for July 30, 1966. The D-21, Article 504, would carry a full fuel load for the first time. This meant it was heavier than on any of the previous launches. The launch would be made at a slightly higher speed and at exactly 1.00 g. Park, as before, was flying the launch aircraft, Article 135. His launch control officer was Ray Torick.
Article 134 was used as the chase plane for the launch. It was flown by Art Peterson, with Keith Beswick in the backseat to film the separation. The chase M-21 flew about three hundred feet to the right and about one hundred feet behind the launch M-21, at a speed of more than Mach 3.[315]
As the two planes flew in formation, Park reached the launch speed of Mach 3.25, began the shallow dive, and Torick started the separation sequence. From analysis of the data, it appears that Article 504 climbed more slowly through the shock wave and suffered an unstart. This caused it to strike the back of Article 135. The M-21 pitched up and the aerodynamic loads tore off the forward fuselage. Park and Torick were subjected to in-credible g forces as the fuselage tumbled. The cockpits depressurized and Park and Torick's suits inflated. The two crewmen ejected and landed in the ocean 150 miles offshore. Park was picked up by a helicopter, but Torick, having survived a Mach 3 breakup and ejection, drowned when sea water entered his pressure suit.
Kelly Johnson was devastated by the death of Torick and personally canceled the D-21/M-21 program.[316] He had long feared launch problems and was unwilling to see any more pilots killed. He concluded that the Mach 3 launch of so large an aircraft could not be justified from a safety point of view.[317] A number of D-21s had already been produced, and rather than scrapping the whole effort, Johnson again proposed to the air force that they be launched from a B-52H. This, however, would require major modifications to the D-21. It would take a year to complete the work.
THE D-21B
Using the B-52H as drop plane entailed a complete rebuilding of the D-21s.
The process involved removing the outer wing panels, inlet cone, and ramjet from the airframe. Attachment points were added to the top of the fuselage for the pylon and to the bottom for the rocket booster. Once this was completed, the drone would be reassembled and its systems checked out.
Due to the major changes made, the drone was redesignated the "D-21B."
The program code name remained Tagboard. Conversion work was under way in Burbank in late 1966 and early 1967.
The rocket booster used to propel the D-21B to ramjet ignition speed was longer and heavier than the D-21 itself. The booster was 44.25 feet long, had a diameter of 30.16 inches, and
weighed 13,286 pounds. It was cylindrical with several ridges, giving it the appearance of a water pipe. At the pointed nose was the propeller of a ram air turbine, which spun to provide electrical power. The solid rocket motor produced an average thrust of 27,300 pounds and burned for 87 seconds. To stabilize the assembly during the burn, a fin was attached to the bottom of the booster. To provide ground clearance, it folded to the right while attached to the B-52. The total weight of the D-21B and its booster was over 24,000 pounds.
Two B-52Hs were modified to act as launch planes. The major modification was the addition of two large pylons to hold the D-21B. These were much larger than the pylons for the Hound Dog cruise missile normally carried by B-52Hs. They bolted to the existing attachment points and involved no changes to the wings' structure. Inside the two B-52s, two LCO stations were added to the rear of the flight deck; each station was independent, with its own command and telemetry system, as well as a periscope.
The command system allowed the LCO to activate postlaunch functions normally operated by the drone's programming (engine ignition, booster jettison, telemetry, hatch ejection, and destruct). This provided a backup should the programming fail, or if it was necessary to change the timing.
The telemetry system recorded data on the functioning of the flight control, propulsion, fuel, booster, electrical and hydraulic systems, engine and equipment temperatures, as well as the D-21B's Mach number, direction, and location. This information was used to monitor the launch, and for postflight analysis of any problems. The command and the telemetry systems were duplicated for reliability. A stellar navigation system was also added to the B-52. This was used to update the D-21B's own inertial navigation system during the long flight to the drop point.
Finally, an air-conditioning system provided air to the D-21B for temperature control and to drive the auxiliary power unit (APU).[318] Temperature control was critical, as the D-21B would be "cold soaked" by the negative-58 degree F conditions during the long flight to the launch point. After the drop, the D-21 would be suddenly heated by the acceleration to Mach 3-plus cruise. This put severe thermodynamic stresses on the vehicle and its systems.[319]
The first of the B-52s arrived at Palmdale on December 12, 1966, to begin the modifications. The 4200th Test Wing at Beale Air Force Base was assigned to undertake both the test launches and the operational missions.[320]
Before launch, the LCO would lower the booster fin, turn on the telemetry, test the automatic flight control system, and turn on the fuel and the observation camera. The drop would be made at about 38,000 feet. The assembly would fall free for a moment, then the booster would ignite. It would accelerate forward, then pitch up into the climb. At 50,000 feet, it would go into the final climb trajectory. As it passed through 63,000 feet, the destruct system would be activated; the LCO could destroy the vehicle should it go off-course. At 74,000 feet, the ramjet would ignite.
Soon after, the APU would take over the electrical load. When the D-21B reached an altitude of about 80,000 feet, two explosive bolts would fire and the booster would drop off. The D-21B's automatic flight control system would then go to a preprogrammed Mach number. During the first ten minutes of the cruise, the LCO could send a destruct command to the D-21B.
After this point, the telemetry and command system was turned off.
The D-21B would be controlled during the overflight by an onboard inertial navigation system. This was preprogrammed with the headings, bank angles, and the camera on-and-off points. Should there be a problem, the D-21B would automatically destruct. This would be triggered by any loss of altitude.
When the mission was completed, the D-21 would fly to friendly airspace. Once clear, the command system, recovery beacons, and telemetry would be turned back on. The D-21B could now be controlled by the JC-130 recovery aircraft. Over the recovery zone, the ramjet's fuel supply would be cut off. The D-21B would slow, then go into a dive. As it passed through 60,000 feet, at a speed of Mach 1.67, the latches on the front edge of the hatch would release. It would open like a door and separate from the D-21B's airframe. The recovery parachute would open, and the hatch would be caught in midair by the JC-130. (The procedure was similar to that used to recover reconnaissance satellite capsules.) If the midair recovery was unsuccessful, the hatch would float, and could be picked up by a ship. The D-21B would continue its descent, until it self-destructed at 52,000 feet.[321]
Support for the Tagboard program was starting to grow. On January 18, 1967, Kelly Johnson had a meeting with Deputy Secretary of Defense Cyrus Vance. Vance said he was very much for the project and asked Lockheed to press forward with it. He said that the U.S. government would never again fly a manned aircraft over enemy territory in peacetime.
D-21B/B-52H TEST LAUNCHES
By late summer of 1967, the modification work to both the D-21Bs and the B-52Hs was complete. The test program could now resume. In effect, the development program would have to begin again from scratch. The three successful D-21 flights had provided limited data. They had flown only half the D-21's full range, and the hatch had not yet been successfully recovered. Checks of the navigation system and camera were yet to be made.
The test missions were flown out of Groom Lake, with the actual launches over the Pacific. The first D-21B to be flown was Article 501, the prototype.
The first attempt was made on September 28, 1967, and ended in complete failure. As the B-52 was flying toward the launch point, the D-21B fell off the pylon. The B-52H gave a sharp lurch as the drone fell free. The booster fired and was "quite a sight from the ground." The failure was traced to a stripped nut on the forward right attachment point on the pylon. Johnson wrote it was "very embarrassing."[322]
The first actual D-21B/B-52 test launch was made on November 6, 1967.
It was also a failure — Article 507 was boosted to altitude, but nosed over into a dive after flying only 134 nautical miles. A second launch on December 2 flew a total distance of 1,430 nautical miles before Article 509 was lost. The third attempt, with Article 508 on January 19, 1968, flew only 280
nautical miles. Several other attempts had to be aborted before launch due to technical problems. Johnson felt another D-21B failure would result in the program being canceled, so he organized a review panel to look at the problems.[323]
The resumptions of D-21 tests took place against a changing reconnaissance background. The A-12 had finally been allowed to deploy, and the SR-71 was soon to replace it. The Model 147 drone program was in full swing, with both the high- and low-altitude drones being flown. Finally, the Nationalist Chinese U-2 program was being ended. The latter was the most important — the 147 drones could not cover targets deep inside mainland China. With a 3,000-nautical-mile range, the D-21Bs could act as a replacement.
At the same time, new developments in reconnaissance satellite technology were nearing operation. Up to this point, the limited number of satellites available restricted coverage to the Soviet Union. A new generation of reconnaissance satellites could soon cover targets anywhere in the world. The satellites' resolution would be comparable to that of aircraft, but without the slightest political risk. Time was running out for the Tagboard.
It was not until April 30, 1968, that the next D-21B launch was made.
Article 511 suffered the same fate as the earlier missions, flying only 150 nautical miles.
The next mission, by Article 512 on June 16, was everything Johnson had hoped for. It flew 2,850 nautical miles — the design range — and also reached an altitude of 90,000 feet. During turns, the ramjet blew out, but it reignited each time. This confirmed the wind-tunnel results. At the end of the mission, the hatch was successfully recovered. Although it had carried no camera, Article 512 had demonstrated the complete mission profile.
Events, however, would show there was still much work to be done.
The next two missions ended in failure. Article 514 traveled only 80 nautical miles before it failed, followed by an even less successful flight of 78 n
autical miles by Article 516. All these failures put Lockheed in a bind — the D-21B was overrunning costs, and Lockheed had to put its own money into the program. Although Johnson still felt the project had a great deal of promise, he knew there were still very difficult technical challenges ahead.
The final flight of the year gave some optimism. On December 15, 1968, Article 515 flew 2,953 nautical miles. This mission carried a camera; when developed, the photos proved to be fair.
The mission of February 11, 1969, was the first attempt to fly a "Captain Hook" mission profile. This involved a launch near Hawaii, a flight path taking the D-21 over Christmas Island or Midway, then back to Hawaii and the recovery zone. It simulated an operational mission. The D-21B was lost after flying 161 nautical miles. Lockheed believed the cause was water in Article 518's guidance system, but this could not be proven.
This was the final disappointment of the test program. Two fully successful flights followed — Article 519 on May 10, 1969, and Article 520 on July 10, 1969. Both missions were in excess of 2,900 nautical miles, and both hatches were recovered. The photos from the first mission were fair, while the second were considered good.
The twin successes demonstrated the D-21B's design performance, and the air force now considered it ready for operational flights. The air force and CIA proposed to President Nixon that the D-21B be used on "hot" missions over Communist China. Kelly Johnson felt the probability was high that approval would be given. If the D-21B was successful, he felt it had a great future. In anticipation of the approval, the remaining D-21Bs were brought up to the configuration of Articles 519 and 520. Johnson also began looking at ways to recover the complete airframe. The initial recovery studies looked promising.[324]
In the early fall, Nixon gave the go-ahead.
SENIOR BOWL — THE TAGBOARD OVER CHINA
With the approval to start operational missions, activities shifted to Beale Air Force Base. The two B-52Hs were moved to the base. It was home of the 465th Bomb Wing, so the two modified aircraft would not be noticed.
Dark Eagles: A History of the Top Secret U.S. Aircraft Page 18