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Rocket failure cuts short circumlunar mission again

On Nov. 22, 1967, the USSR made its second attempt to send an unmanned prototype of its L1 spacecraft on a lunar flyby mission. It was also the fourth launch for the UR-500/7K-L1 complex, the nation's most powerful space vehicle. The Soviet Moon shot took place in the wake of the first test flight of the America's giant Saturn-5 rocket designed to put humans onto the lunar surface, making Moscow's response even more so critical. However, the UR-500K rocket failed again, this time during the operation of its second stage, dealing another to blow to the Soviet effort.

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launch

The 7K-L1 No. 5L vehicle lifted off on November 22, 1967.

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The 7K-L1 No. 4 mission at a glance:

Spacecraft designations 7K-L1 (11F91) No. 5L
Launch vehicle 8K82K (UR-500K, Proton-K) No. Ya10723001 / Block D1 (11S824) (No. 13L)
Launch site Tyuratam, Site 81, "Right" pad
Crew Unmanned
Spacecraft mass 5,017 kilograms
Launch date and time 1967 Nov. 22, 22:07:59 Moscow Time
Mission results Failure during Stage II ascent

(52)

Boosted by a success

The launch date for the 7K-L1 No. 5L vehicle was driven in big part by the domino effect of delays in the previous L1 mission. The assembly of Vehicle No. 5 was already taking place in early 1967. As of February 13, the delivery of the 11D58 engine for the mission's Block D space tug was expected on March 10, followed by the rest of the stage on March 20. However, the head of the TsKBEM design bureau Vasily Mishin noted at the time, that the descent module and the aggregate compartment had to be assembled with mockup equipment, while engineers were still waiting for the delivery of flight-worthy instruments.

As of April 30, 1967, the launch of the 5L ship was expected between July 1 and July 5, but by May 5, it had already slipped to the period between June 27 and July 5, 1967.

Like its predecessor, Vehicle 5L was waiting for a parachute container redesigned in the wake of the Soyuz-1 accident. And similarly, in June, Vehicle No. 5L had to wait for crucial star sensors, designated 99K, 100K and 101K, for the troublesome attitude control system which had to be urgently reworked based on the experience in the previous mission.

By June 16, the launch of Vehicle 5L shifted to between August 15 and 20, 1967, however by that time, the ship was apparently still in Podlipki and its delivery to the launch site was expected around the end of August 1967. (774)

Another delay came with the failure of the 7K-L1 No. 4 launch on September 28. Head of cosmonaut training Nikolai Kamanin quoted Dmitry Ustinov as saying during a meeting on October 7 that the latest failed launch had set back the L1 project by two or three months. It was now clear than no manned launches either on the 7K-OK or the 7K-L1 sides of the Soviet lunar program would be possible in 1967. Around November 14, the expert commission reviewed the status of the L1 project and concluded that between four and six unmanned flights of the 7K-L1 spacecraft would still be required, before it could be certified to carry a crew. During the same meeting, the launch of the next unmanned L1 spacecraft was set for November 21 or November 22, 1967. (820) The timing of the window was chosen to allow a flight around the Moon.

The L1 program got a major morale boost at the end of October, when a pair of Soyuz 7K-OK spacecraft, under cover names Kosmos-186 and Kosmos-188, made a successful docking in the Earth's orbit.

Final preparations

As usual, the veteran of the Soviet rocket development program Georgy Tyulin was working tirelessly at the launch site in Tyuratam processing Vehicle No. 5L. As of November 16, all preparations were proceeding on schedule for a November 22 liftoff.

On November 18, at 10:00, a group of 12 cosmonauts, including Aleksei Leonov, Pavel Popovich and Georgy Dobrovolsky, who were preparing for flights around the Moon aboard the L1 spacecraft, departed Star City for Tyuratam on two Il-14 and one An-12 aircraft to watch the launch of Vehicle No. 5L. The next day, the State Commission convened at the launch site, where Tyulin and Shabarov reported that the preparations for launch had been proceeding as planned. The head of the Soviet ground control network Ivan Spitsa then reported that the flight controllers had been conducting final dress rehearsals.

G. P. Melnikov reported on the specifics of the lunar flyby trajectory and warned that after flying around the Moon, the descent module could land as far as 1,500 or 1,700 kilometers from the projected point. As a solution, Melnikov also proposed to install a 6-kilogram Krab TV camera on the spacecraft, whose live images could allow better tracking the capsule during its descent through the atmosphere. According to Kamanin, this proposal was approved but it is not clear whether the camera could be installed on Vehicle No. 5 or subsequent ships.

Air Force General Aleksandr Kutasin, who was in charge of search and rescue operations, reported that his teams were ready for recovery operations in the Indian Ocean and over land.

The State Commission reconvened on November 20 at 17:00, where managers and engineers reported on the readiness of the vehicle for launch on November 22, 1967, at 22:07 Moscow Time. Managers expressed their concern about many incidents of negligence during the launch campaign and quoted endless failures of equipment. It was decided to delegate the technical leadership of the project to develop new measures for improving the reliability of all systems. Obviously, attention was focused on Plant 19 in the city of Perm, which had manufactured engines for the first stage responsible for the September 28 failure. After the accident, Valentin Glushko, who led the engine design, had visited Perm and reported some improvements, but overall, he described the production process as unsatisfactory. Deputy Minister of Aviation Industry Vasily Kazakov, whose ministry oversaw Plant 19, promised to improve quality control and assured the commission that the first-stage engines would perform as planned in the upcoming launch. (820)

L1 No. 5L mission fails two minutes into the flight

On the day of the launch, November 22, the weather service predicted a complete cloud cover at an altitude of just 100-150 meters, winds reaching 5 or 8 meters per second and precipitation. Still, the final preparations for launch went on at full swing.

In the evening, General Kutasin returned from a trip to Karaganda and Novosibirsk, located along the ground track of the upcoming mission, and reported that search and rescue teams were ready to support the launch.

Despite the bad weather forecast, the night sky over Tyuratam turned clear by the time the launch window approached and the moon rose right above the horizon, providing a dramatic backdrop for the rocket towering on the pad. Still, strong gusts of wind reaching 15 or 17 seconds per second forced officials to stay off the viewing pad until just five minutes before launch. According to Kamanin, the group included Vladimir Chelomei, Valentin Glushko, Vasily Kazakov, Lobov, Yuryshev, Mrykin and Kurushin.

The UR-500K rocket with the L1 No. 5L spacecraft lifted off on Nov. 22, 1967, at 22:07:59 Moscow Time from the "Right" launch pad at Site 81 in Tyuratam. The first stage fired for two minutes lifting the vehicle into the stratosphere, but the second stage failed almost immediately upon the ignition. According to Kamanin, observers in Tyuratam could see the firing of the emergency escape system taking the descent module of the L1 spacecraft away from its stricken rocket and ending any further hopes for the flight.

Kamanin immediately asked General Kutasin to dispatch aircraft to pinpoint the crash site of the rocket and locate the descent module, which was now expected to touch down between 250 and 300 kilometers from Tyuratam. (820)

Post-flight analysis

Around 40 minutes after the failed launch, all the members of the State Commission and the chief designers gathered at the vehicle assembly building at Site 2. By that time, it was already known that Engine No. 4 on the second stage of the UR-500K rocket had failed to develop full thrust, and that the three remaining engines had been able to keep the vehicle on its correct path for only 3.9 seconds, before the rocket pitched beyond acceptable margins. As a result, the vehicle safety system, SBN, cut off the engines and triggered the emergency escape system.

Urgent checks via the Krug radio direction-finding system failed to detect short-wave signals from the spacecraft, but around an hour later, a search aircraft did locate the descent module thanks to the Pritok radio beacon operating in UHF. The spacecraft had landed 80 kilometers southwest of Dzhezkazgan and 285 kilometers downrange from the launch site.

To find the culprit in the failure of the propulsion system, which had been manufactured in 1966, an investigative commission was formed. (820)

On the morning of November 23, at 09:00, Kamanin and Aleksei Leonov, who headed the cosmonaut team training to fly L1 spacecraft, accompanied search and recovery technicians aboard an Il-14 aircraft heading to the landing site of Vehicle No. 5L. The descent module was reported transmitting signals throughout the night, helping search aircraft make several overflights of the landing site. At 10:17, after flying along the ascent path of the mission, the Kamanin's group discovered the crash site of the UR-500K rocket. (820) It was apparently located 300 kilometers downrange from the launch site and 110 kilometers southwest of town of Dzhezkazgan. Another 13 minutes later, the team saw the descent module and its red and white parachute. It was already surrounded by helicopters and personnel.

The group landed at an airfield in Dzhezkazgan and inspected its rudimentary runway. Although it had no pavement, thanks to a bitter cold reaching minus 17C at the time, the ground was hard enough to receive practically any aircraft. Therefore, the officials requested the dispatch of an An-12 transport plane to Dzhezkazgan to evacuate the descent module.

The group then flew a Mi-4 helicopter to the landing site. After a 32-minute flight, the helicopter landed just 50 meters from the descent module. A separate evacuation team inspected the vehicle, removed its APO self-destruct charge and began preparing the capsule for airlifting on a heavy Mi-6 helicopter.

By the time Kamanin arrived, the capsule had already been returned to the upright position, but a cracked external glass on the starboard window and scratches on the body of the vehicle had clearly showed that it had been thrown on its side by the parachute. The capsule's short-wave antenna, embedded into the parachute strings, was also found severed.

Moreover, when the technicians attempted to drain hydrogen peroxide, which serves as propellant for attitude control thrusters in the module, its spontaneous combustion caused a small fire. Fortunately, the team quickly suppressed the flames, but one helicopter pilot and an engineer from TsKBEM, who rushed to help, got burns on their hands when operating fire extinguishers.

Leonov, Kamanin and other air force specialists then walked back 550 meters along the trail left by the capsule on the ground after landing, when its parachute acted as a sail propelled by a 12-meter per second wind.

At the touchdown point there were no typical burn marks usually left by the soft-landing rocket motors, indicating that they had fired at a higher-than-the-required altitude of 1.2 meters from the ground. (820) The investigation revealed that the solid propellant motors of the capsule had fired at an altitude of 4.5 kilometers instead. (52)

Post-flight analysis

After returning to Tyuratam, the State Commission reconvened at 17:00 on November 23. According to Kamanin, top managers, including Mishin, Shabarov, Trufanov and Chelomei, expressed displeasure with the "slow pace" of recovery operations and demanded that the remnants of the failed rocket be delivered to the launch site no later than November 24. However General Kurushin, the head of the Tyuratam test range, asked for more patience with his personnel. Kamanin, who had just tasted the cold and wind faced by recovery specialists in the midst of the Kazakh steppe, echoed Kurushin. (820)

The subsequent probe into the failed launch apparently revealed more issues. Immediately after liftoff, problems with the draining system in the tanks of the first stage had been detected, even though the rocket was able to continue a normal ascent for the first two minutes of the mission. However, after separation of the first stage, a faulty engine ignition sequence on the second stage, caused engines No. 2 and No. 3 in the 8D412K propulsion system to develop their preliminary thrust slower than required. (537)

In the meantime, the nozzle on Engine No. 4 disintegrated at T+125.5 seconds in flight, leaving it without thrust. The damage was apparently caused by the explosive ignition of propellants and the resulting violent pressure fluctuations below the nozzle during the faulty ignition. After the flight control system had detected the lack of thrust in the propulsion system, it issued the emergency engine cutoff command, or AVD in Russian, at T+129.9 seconds in flight. The emergency escape mechanism was also triggered.

As a silver lining for the failed L1 mission, the activation of the emergency escape system during the flight provided invaluable data for upgrades to all the safety mechanisms and procedures on both the 7K-L1 and 7K-OK spacecraft... But the Soviet lunar exploration effort was set back one more time...

To be continued

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The article and illustration by Anatoly Zak; Last update: November 22, 2017

Page editor: Alain Chabot, Last edit: September 28, 2017

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apollo

The first Saturn-5 rocket launches the Apollo-4 mission on Nov. 9, 1967. Click to enlarge. Credit: NASA


stand

A stand in the city of Perm used for testing of RD-275 engines on the first stage of the Proton rocket. The engine's performance was a key concern in the runup to the launch of the UR-500K-7K-L1 No. 5 vehicle on Nov. 22, 1967. Credit: Roskosmos