And now onto the additional N11 tests, along with the first N1 test. No prizes for guessing how well it goes...
As 1965 closed and 1966 began, the Soviet Space Programme was finding itself in a predicament. The Soyuz was stubbornly behind schedule, the N11 needed more flights to verify it, and the N1 Block A would not be ready until the third quarter of the year.
The March of that year saw only the third N11 test launch, and this time, they needed it to work, since this one would be carrying an experimental payload for the Soviet Military. To provide them with round-the-clock satellite communications, this would be the first time that they would attempt to place a payload into GSO.
Lift-off, and the Blocks B, V, and G burns were performed to well within the accepted margins, further verifying the N11 which successfully carried the test payload and Block D into Orbit. The Block D was commanded to ignite its main engine, and one long burn later, had pushed the apogee of itself and its payload to an altitude of 35,516 Km, just below the required point for a Geosynchronous Orbit. Now they needed it to fire again, not only to place the payload into the proper GSO, but also to prove that the Block D’s RD-58 could be restarted in Space, something that would be vital for the LK, and especially the Soyuz LOK. The command was given to fire the engine. And nothing happened. Repeated attempts were made to try and fire the Block D engine, but it refused to respond.
The RD-58 engine of the Block D required the use of ullage thrusters to settle the propellants and provide enough positive pressure to allow a main engine start. The investigation into the Block D failure would conclude that the Block D’s ullage thrusters had failed, preventing a main engine start. They would have to re-design it to improve its reliability for future flights, though the engineers felt it was not too difficult to achieve.
While two partial failures in the first three flights of a new launch vehicle was relatively impressive for the Soviet Union at that time, for Mishin, it wasn’t good at all. To beat the Americans in the goal of landing a man on the Moon, then returning him safely, these were failures that he couldn’t afford to suffer. Especially since with NASA publicly broadcasting their every achievement and failure, he was under no illusion that they were closing the gap on them. They still needed to test the Block A for the N1, and the only way that they could was with an all-up N1 launch, now scheduled for the third quarter of the year.
June would give him a much-needed boost, as in a repeat of the previous attempt, this N11 again tried to place a payload into GSO. This time, the N11 and the Block D performed well, placing its test payload - a basic communications satellite - into a low-inclination GSO. The Soviet State Media were quick to announce the success of this test, demonstrating their ability to place payloads to where they would appear to be stuck in place in the sky, and would permit constant, reliable communications for the USSR.
Now August 1966 came, and the N1 was finally on the pad for its first test launch. This would mark the first time that the USSR, and indeed anyone, had ever attempted to operate 24 engines at once in a flight. And Mishin knew full well that Kuznetsov’s NK engines hid a serious design flaw, they were single-use only. They could be fired once, and that was it, meaning that the very first time the engines at the base of the Block A, and in fact all the N1 and N11 stages, were fired for the first time at launch. The batch-testing of engines they had been performing, combined with the good flight data received from the N11 flights however, gave Mishin and the engineers the confidence to take the chance.
In the late afternoon, the 24 NK-15 engines were ignited in sequence, the moment the total thrust surpassed the weight of the N1, it rose off the pad, accelerating quickly as all the engines were brought up to full power. The selected audience bore witness to the most powerful launch vehicle that the Soviet Union had ever built, its exhaust plume some three, maybe four times greater than the total length of the N1 itself! And quickly becoming the only easily noticeable part as it continued its accelerating climb.
For the first 90 seconds or so, all the systems appeared to be functioning normally, and it appeared that the flight would succeed. Then the sensors indicated something alarming, something was seriously wrong with the Block A. Some of the engines had ceased functioning, and the stage was beginning to break apart. The auto-destruct was activated by Range Safety, and as the powerful LAS pulled the Soyuz-LOK mock-up away, the N1 was enveloped in a fireball, its debris arcing up before falling back to the ground.
Failed first flights were nothing new, and there wasn’t anything terribly surprising about this being any different. But that didn’t make it any less painful for the designers and engineers who had spent years working on it, as the process of gathering what debris they could and investigating the failure was started. It was eventually determined that somehow, metallic slag had entered the combustion chamber of the No.22 engine about 95 seconds into the flight and caused it to explode, damaging the engines on either side as well as a portion of the Block A structure itself. The KORD system could not react fast enough to shut down the damaged and destroyed engines in time and the knock-on effects caused the entire stage to structurally fail. They decided that they couldn’t risk another test flight until they had at least managed to install filters into the engines, along with other measures to safeguard the engines to prevent a repeat of what had happened, and it would be safer to have at least another N11 test flights to check the improvements prior to another N1 test launch. The Soviet Propaganda Press announced the flight to the west as a complete success. Television footage of the launch showed it gracefully climbing higher and higher having cut the explosion out. The mission was announced to the general public as a suborbital spaceflight and a test of the Soyuz LOK's launch abort system. It even showed footage from camera's mounted on the N1 of the upper stratosphere (40 km) and claimed it was outer space. Even a complete failure was turned into a prestigious victory, coming over a year before NASA's first planned Saturn V test. Many western sources claimed a Soviet Lunar mission was imminent, while the reality remained, a lot more work needed to be done before either side could truly showcase their respective dream rocket.
That next N11 test flight was in the middle of December. With the NK engines now equipped with filters for the propellant feeds, and improved fire-proofing of the critical areas, it was hoped that this test would go well. Fortunately, this flight was as near-as-makes-no-difference flawless, placing it’s Block D/Soyuz payload into Orbit, where the Block D was tested in a variety of manoeuvres to simulate the burns and course corrections for a Lunar Orbital Mission. The Block D performed well, and was seen as ready for use, although the Soyuz was found wanting in a number of areas.