The Nedelin Catastrophe

[Winston]

The Nedelin Catastrophe

https://www.spacesafetymagazine.com...s-launch-padfailures-nedelin-disaster-part-1/
https://www.spacesafetymagazine.com...e/failure-launch-pad-nedelin-disaster-part-2/
Excerpts:

By far the worst launch pad failure, the Nedelin Catastrophe, took place in 1960, before the space age had even begun. It is well known that in the USSR launch decisions were at least as much political as technological, and that it sometimes cost lives: the death of Vladimir Komarov when he flew on a rushed Soyuz 1 is a case in point. But no misguided launch decision cost as many lives as the Nedelin Catastrophe, the deadliest incident in rocketry history. Russian rocket designer Boris Chertok described its impact: “..the first R-16 missile, named ‘article 8K64,’ killed, on average, more people without leaving the launch pad than did any 10 V-2 missiles that struck London during World War II.” This devastation was wrought from an inert missile – no explosives were involved at all. As Chertok described it, the incident was so far outside the norms of spacecraft development that “one cannot explain it using the terminology or classification system of reliability engineering developed for rocket technology.”

The R-16 intercontinental ballistic missile (ICBM) was the brainchild of Mikhail Yangel. Intended to replace the R-7, R-16 was designed to use non-cryogenic fuels, deemed to be “more practical” because a missile could be readied much more quickly as a result of simpler fueling mechanisms. The selected fuels were UDMH oxidized with a 73% nitric acid/27% nitrogen tetroxide blend, a combination known as “the devil’s venom,” and for good reason. The fuels are toxic and corrosive in liquid form; when burned, they produce poisonous gas.

Air Marshal Mitrofan Nedelin, commander of the USSR’s Strategic Rocket Forces, was placed in charge of the R-16 development. Looking to score political points by having the rocket ready for the anniversary of the Bolshevik Revolution, Nedelin pressured Yangel and the rest of the R-16 team (some say Yangel was a willing participant here) to accelerate their timetable. They did this primarily by ignoring all of the quite sensible safety measures in effect at the time. The irony is that the missile was considerably ahead of schedule; it had been expected to conduct flight testing 10 months later, in July 1961. However, the high-boiling point propellant camp felt in competition with the cryogenic liquid oxygen camp of ICBM development and wanted to show up lead Soviet rocket engineer Sergei Korolev and his R-9 missile, then under development.

Due to in-fighting in the Soviet rocketry community, Yangel was unable to engage the best man for the job of designing the electrical guidance system for the R-16. Instead of Nikolai Pilyugin, who had designed most of the major guidance systems of the time, Yangel had to make do with Boris Konoplev, a brilliant inventor and expert in radio engineering, but not a very systematic individual. As a result, his systems had seen limited testing when they were first installed into the R-16 and they were accompanied by ambiguous instructions.

A number of electrical system glitches arose, as may have been expected, in the run up to the anticipated October 24 launch from Tyuratam Launch Complex, the predecessor to Baikonour Cosmodrome. Nedelin responded to the glitches by calling for longer hours and more diligent effort from the workforce. By the time October 24 arrived, they had been working for 72 hours straight.

Building Up a Disaster

Due to the known hazards associated with the R-16’s fuel, there were certain precautions in place to prevent any accident from having catastrophic effects. During fueling procedures, all non-essential personnel were supposed to evacuate the area surrounding the launch pad. Any repairs or configuration changes to the rocket were supposed to be performed on a dry system – without any fuel. In the event, the wisdom of such measures was demonstrated only too well by their absence. Nedelin himself reportedly liked to set up a chair at the pad to watch the proceedings. That’s where he was October 23-24, setting a good example for his workers by being on the spot – and not-so-subtly indicating that they had better be there too.

The engineers responsible for preparing and fueling the R-16 were doing so for the first time. Despite Korolev’s example, Yangel had decided that an engineering model was not needed for the technicians to practice these measures. Whether he based that decision on the desire to save time he thought that the simpler design of the R-16 was more intuitive and needed no practice is not known. In any event, when these workers began preparing the R-16 for launch on October 23, it was the first time they had been put through the procedure.

The rocket was fueled successfully, and there the checklist stopped. Yangel decided to change the planned procedure to compensate for an unreliable blowout mechanism that no one had stopped to fix. Instead of a reusable valve that could be tested, the R-16 has been designed with a blowout disc that allowed the propellant to flow into the turbopump chambers. This pyrotechnic mechanism was never really perfected and had no reliable monitoring system. Essentially, the operators were never quite sure whether the disc had really ruptured or not. Any single disc could not be tested because they were not reusable. Yet, if the discs did not rupture, the rocket’s engines would not ignite. With this in mind, Yangel decided to make sure the discs ruptured as intended by having technicians crawl into a hatch and listen for the gurgling sound the flowing liquid would make if the discs had blown properly. They wore no protective masks, since masks would obscure their hearing. Had there been a leak, all the monitoring technicians could have died of poisoning. “Chief Designer Yangel and military acceptance committed a fundamental error by clearing the missile for flight-tests when it was already known that the disc opening mechanism was unreliable,” Chertok averred.

With the technicians in place, the order was given to blow the second stage discs. Listening hard for the subtle sound of flowing fluid in the second stage, the technicians were startled instead by a shock and a noise from the first stage, followed by a burnt smell. First stage discs placed to cut off the gas generator had been blown by mistake for the second! Miraculously, no one had been injured yet, although they did find a small fuel leak through the turbopump assembly shaft seal.

This was only the most egregious of a number of problems that occurred during preparation, tied to problems with the control panel, onboard electrical control system, and second stage onboard battery. The onsite State Commission responsible for final decisions affecting launch readiness went into a huddle. Only one individual, the firing range department chief Lieutenant Colonel S. D. Titov felt called upon to recommend the proper procedure: “Drain the propellant components, neutralize the missile at the firing range, and send it to the factory for modification.” Despite a number of individuals present having the stature and knowledge to know better, none of them supported Titov; Nedelin carried the day with the decree to correct the electrical circuits in situ. “We’ll modify the missile on the launch pad,” he reportedly declared. “The nation is waiting for us!”

[continued in next post]

R-16 Saddler

https://en.wikipedia.org/wiki/R-16_(missile)
The missile was 30.4 m long, 3.0 m in diameter and had a launch weight of 141 tons. The maximum range was 11,000 km with a 5-6 Mt thermonuclear warhead and 13,000 km with a 3 Mt warhead. The missile had a circular error probable (CEP) of 2.7 km.

Link to excellent R-16 image gallery:

https://www.b14643.de/Spacerockets/Specials/R_and_UR-Missiles/Gallery/R-16/R-16.htm

 

[Winston]

[continued]

They worked all night. One bundle of wires that was removed and replaced had all their coverings melted as a result of a short circuit from the first stage’s pyrotechnic cartridge; the wires were in direct contact with each other. Propulsion engineers still weren’t sure whether the second stage blowout discs had blown, since the monitors had been distracted by the first stage; they attempted to verify the situation by smell.

The morning of October 24 arrived. Nedelin was still seated by the launch pad, a position that had become if anything, even riskier. NII-4 chief General A. I. Sokolov had the temerity to suggest to Nedelin that it might be safer to move away from the fueled, poorly controlled missile; Nedelin called him a coward. The offended Sokolov left directly for Moscow, a move that almost certainly saved his life.

The evening of October 24: It was time, once again, to blow the second stage discs. No longer trusting the electrical system which was clearly riddled with faults, engineers undertook to detonate each disc manually, powered by a battery carried up the service ladder.

T-30 minutes: The service platforms and access ladders were swarming with people moving both up and down, scurrying to correct last minute glitches that had popped up all over the system, while the countdown continue, inexorably. A lucky few individuals decided to take a cigarette break in the bunker smoking room. One of them was Yangel. Another was OKB-586 lead designer Khachaturyan who had just finished manually blowing the explosive discs. This is Khachaturyan’s account of what happened next, as recorded by Chertok:

“When I went down into the bunker I found the always calm and collected Matrenin [the missile crew chief] in somewhat of an agitated state, which Aleksandr Sergeyevich explained saying that Grigoryants was putting tremendous pressure on him and always rushing. Continuing our conversation, we stopped by the smoking room and had a cigarette. I started to reassure him, uttering a bunch of platitudes. And suddenly at that moment we heard incomprehensible chaotic, violent noises and explosions. Matrenin and I ran into the control room. Senior Lieutenant V. N. Taran, the preparation and launch control panel operator, and engineers from our design bureau whose responsibilities included monitoring the pre-launch circuit setup, were there at that time. They looked horrible: ashen and wild-eyed. I dashed to the periscope and saw our missile burning on the launch pad. This hideous conflagration was accompanied by the explosions of the solid-fuel braking engines and the high-pressure tanks.”

An ill-advised flip of a switch whose circuitry was poorly design had ignited the second stage, still on the launch pad. Its flames in turn ignited the fully fueled first stage, creating a massive fireball. The lucky ones, like Nedelin, died instantly. A video camera had been set up to record the launch; instead it recorded figures stumbling off the launch pad engulfed in flames. The fire reached 3,000°C, melting tar on the road and trapping those who tried to run. Those who didn’t bake or burn died of toxic gas inhalation. A few managed to run to the edge of the launch site, where they got tangled in the barbed wire fence intended to demarcate the safety line.

100 civilian and military personnel had been engaged in work on the R-16. An additional 150 spectators had come to watch the momentous event from up close. All but a handful of them died that day.

Three Decades of Silence

It was decades before a full account of the Nedelin Catastrophe came out. Despite at least 150 people killed (the real number remains unknown, as the official death toll was either never counted or revealed), the catastrophe was completely covered up. An apparently victorious nation happily launched the first man to space just six months later. Relatives were told their loved one had died in a plane crash – only later did these relatives discover just how many “plane crashes” there had been on October 24. Bodies of military service members were buried in a mass grave on the launch site; it was not until 1963 that they were given a memorial marker. The bodies of deceased civilians were sent home to their families. Today, Site 41 at Baikonour Cosmodrome remains as an abandoned lot, with a small monument listing the names of 54 people’s remains could not be identified.

It would be nice to conclude that the horrific outcome of this incident was a radical change in the Soviet approach to launch vehicle safety, but history has shown otherwise. It was not until four decades later that this account became public – and Marshall Nedelin is still seen as a Russian hero due to his World War II service, a reputation unsullied by his subsequent errors. Even those who were aware of all the facts at the time seemed anxious to forget them as soon as possible. The investigative commission, after declining to punish anyone for the catastrophe perhaps rightly concluding that anyone still alive had been punished enough, went on to demand cleanup of the launch site within 10-15 days and a fresh launch attempt within one month. In fact, the next launch attempt was three months later – and it failed too. Luckily no one died on the second time around.