Post 2: The First Rumble
- The President’s Daily Brief, 7th May 1970
The latest photography from a satellite over Tyuratam shows that the Soviets are still working on their largest space booster—assembled on one of the pads at Complex J and therefore dubbed ‘the J-Bird’ by U.S. observers of Soviet rocketry. The first booster of this type to be tested blew up on the other pad at Complex J last July during an attempt to launch a payload to the Moon. The extensive damage to that pad is still being repaired.
The J-Bird is the Soviet counterpart of the Saturn V, but [REDACTED] it cannot deliver as large a payload to the moon. The difference in performance is in the high-energy propellants in the upper stages of the Saturn.
The Soviets would have to use two J-Birds to put a man on the Moon—a rendezvous would be necessary. Thus, both launch pads at Complex J would be needed. The link-up mission of Soyuz 9 and Soyuz 10, currently in progress, is believed to be making use of a different docking system than previous flights, and could be a test of the system planned for connecting in orbit the components of dual-launch lunar mission. Interplanetary probes and circumlunar missions can be handled by one J-Bird, which could also be used to orbit a permanent space station weighing 100 to 150 tons. An unmanned lunar landing and return mission could also be launched.
Because of the problems the Soviets have been having with their large space boosters, the intelligence community has estimated that they probably will not be able to make a lunar landing before 1973.
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With the successful completion of the record-breaking Soyuz 9/10 mission, attention at TsKBEM was focussed back towards the lunar mission, and in particular getting the N-1 into space. The priorities agreed at the Ministerial meeting in May 1970 were quickly confirmed in June via Decree 437-160, directing Mishin’s team to develop the enhanced N-1F version of the booster that would be needed for the expanded L3M lunar mission. This Decree was followed in September by the formal approval of L3M by the Military Industrial Commission, the VPK, making the dual-launch lunar mission the official policy of the Soviet government. TsKBEM would fly the last remaining Zond probe in October, continue development of the 7K-T Soyuz ferry for Phase 1 of Chelomei’s Almaz space station, and begin advanced planning for the MKBS space base, but the overriding priority was now, once again, getting N-1 off the pad and into space.
Following the disastrous loss of N1-5L in July 1969, much work had gone into improving the rocket to avoid such costly failures in the future. In particular, at the insistence of Vladimir Barmin, the Chief Director of launch facilities, the N-1's KORD control system was modified to prevent any engine shutdown command being issued until after the rocket was clear of the pad. The 5L explosion had completely wreaked the pad at Site 110 East, and Barmin wanted to ensure that any future failures would happen well away from his precious facilities.
Other changes included the addition of a fire suppression system in the N-1 Blok-A, contained within large external sleeves added to the outside of the first stage in the most visible change to the rocket’s appearance. Additionally, more robust partitions were added between the engines, with the aim of minimising the damage should one of the NK-15s explode, as had happened on the previous launch. The NK-15s themselves were subjected to more rigorous testing and extra precautions to avoid contamination that might cause “foreign object ingestion” - Kuznetsov’s go-to explanation whenever one of his engines failed.
Despite all of these precautions, the launch of N1-6L on 10th March 1971 ended in another failure after less than a minute in the air. This time all of the Blok-A engines performed flawlessly - and that was the problem. The interaction of thirty engine plumes with the wide base of the rocket, seen now for the first time, set up eddies that generated an unexpected roll force. The four small vernier thrusters of the Blok-A were unable to compensate, and within forty seconds the roll had grown beyond the capabilities of the guidance system, which went into gimbal lock. As the aerodynamic forces began to tear the vehicle apart, the KORD system shut off all engines, and the wrecked vehicle descended to impact the steppe, coming down several kilometres from the launch pad, much to Barmin’s satisfaction[1].
Although hugely disappointing, this latest setback did not derail the programme, and work continued in defining the upgrades that would be needed to support N-1F and the L3M mission. The N1-6L Launch Commission had, for the first time, officially acknowledged that the single-launch N1-L3 approach was impossible to safely execute, and so all the energies of TsKBEM’s lunar project team were firmly focussed on the dual-launch mission. It was decided that the existing L3 spacecraft - seven pairs of Soyuz derived LOKs and LK landers in various stages of assembly - would be flown without crews. This would allow in-space testing of critical subsystems, such as the LOK fuel cell technology and LK propulsion system, which could then be adapted for the larger Lunar Expedition Ship (LEK) planned for L3M. For similar reasons, the LK itself would undertake two Earth orbit test flights, in February 1971 as Kosmos 398 and August 1971 as Kosmos 434, in addition to the Kosmos 379 mission that had already been flown in November 1970. All three of these LK test missions, launched on Soyuz-L rockets, were completed flawlessly, and the remaining LK flight models were held for uncrewed lunar missions under the N-1 flight test programme.
Following the conclusion of the L1 circumlunar programme with the October 1970 launch of Zond 8, L1 chief engineer Yuri Semenov had been put in charge of development of the LEK, and he and his team were eager to take advantage of the huge amount of work already done to accelerate their timetables. Semenov also brought his experiences working with Chelomei’s TsKBM on L1 to bear in discussions with Mishin and his other deputies on the direction of the N-1 programme. In particular, Semenov reported favourably on the rigorous review and testing campaign that had finally cured the Proton rocket of its “childhood illnesses”, and impressed upon Kuznetsov the importance of quality control in the manufacture of the NK-15 engines and their uprated NK-33 derivatives that would power N-1F. Although defensive of the work already done by his bureau in front of the other Chief Designers, Kuznetsov privately took note of Semenov’s suggestions and began instituting additional quality checks at his production plant. Most of these improvements related to the development of the new NK-33 engines, but before they would have their chance to fly there was one mission remaining for the NK-15s.
In late May of 1972, N-1 vehicle No. 7L was finally rolled out of the Assembly and Processing Building at Baikonur’s Site 112 (MIK-112) and into the bright Kazakh sunshine, resting in the cradle of its “Grasshopper” Transporter/Erector. The previous month had witnessed a similar scene, when the 1M1 test vehicle, a full-scale non-functioning model of the rocket, had been hauled out for fitting tests. This, however, was the real deal, the fourth flight model of one of the two largest rockets on the planet. Hauled along twin tracks by two pairs of powerful diesel locomotives, slowly, grudgingly, the wheeled cradle and its 230 tonne cargo were pulled out of the building on the first part of its journey to the Raskat launch complex at Site 110.
As N1-7L emerged into the sunshine, the modifications from the previous N-1 vehicles became visible. Aside from a minor update of the white-and-grey colour scheme, a trained eye would note significant modifications as the rear of the rocket emerged. Firstly, the sharp-edged skirt at the N-1's base was replaced by a short cylindrical section joined to a gentle slope starting higher up the rocket’s flanks, and sported four large auxiliary rockets. The modified base would change the aerodynamic loads, whilst the beefed up roll control engines would be able to counter any forces that might still emerge, preventing a repeat of the roll that had doomed vehicle 6L.
Further aerodynamic refinements were evident as the eye moved upwards along the body of the rocket, with the long housings protecting the propellant lines and fire suppression systems of each stage now coming to a streamlined point instead of the previous boxy termination. This was evident on all three stages of the N-1 proper, as were the increased number of telemetry antennas.
The nose of the rocket looked much the same as on the previous three missions, with the distinctive shroud of the L3 complex terminating an a launch abort system which had proven its reliability on vehicle 5L by pulling the modified L1E “Zond” capsule free of what became one of the largest non-nuclear explosions in history. Beneath that shroud lay the L3 complex, consisting of the Blok-G and -D upper stages, a mock-up of the LK lander, and an operational LOK lunar orbiter. This LOK had been fitted out as an uncrewed test vehicle and scientific probe. If successful, it would carry the designation “Zond 9”, a heavier follow-on to the L1 series of Soyuz derived lunar probes that had ended with the launch of Zond 8. If the launch was unsuccessful, the public would never hear of it.
After grinding along five kilometres of Baikonur’s rail network, the four locomotives, now positioned at the opposite end of the Transporter/Erector, began the final push up to Pad 38 of Site 110, the Grasshopper straddling one of the three giant flame trenches extending from the pad itself. Carefully, the giant transport and its moon rocket cargo eased into position, the bottom of the launcher overhanging the wide, circular pit of the launch pad.
At this point the Transporter/Erector was called upon to demonstrate the second half of its name. With a billowing smoke and fumes from the powerful diesel engines, the giant hydraulic rams were forced into their pistons, and the behemoth began to tilt upwards. It took more than an hour to lift the rocket to vertical over the flame pit and bring the adapter ring nestled inside the outer circle of NK-15 engines to rest on the launch pad’s support pads. Once in position, steel latches emerged from the pads and locked the rocket into place. With the launch vehicle secure on its stand, the Grasshopper was disconnected from the rocket’s load bearing hardpoints and the supporting frame was lowered once more, leaving N1-7L a solitary white peak in the late afternoon sun of the Kazakh plain. As the sun set, the rotating service tower swung into place and floodlights lit to allow work to continue through the night.
On the morning of 12th June 1972, the Kazakh steppe was once more shaken by the sound of thirty NK-15 rocket engines firing together. As soon as their combined thrust exceeded the weight of the rocket, N1-7L lifted from Pad 38 and began its ascent to the stars. The redesigned aft skirt and beefed-up control rockets performed perfectly, and as the launcher cleared the tower there was no sign of the roll that had doomed its predecessor. At T+23 seconds the rocket had already out-lived N1-5L. The ascent continued, with the rocket following its pre-programmed pitch and yaw manoeuvres. T+50 seconds had seen the KORD-commanded shutdown of vehicle 6L, but 7L continued to fly true. The clock passed T+68 seconds, making 7L the longest lived N-1 to date, beating the record set by N1-3L, the very first launch, and still there were no signs of trouble. Had they finally defeated the “bobkins” that had plagued the earlier flights?
At T+94.5 seconds, exactly to programme, the six central engines of the Blok-A first stage shut down. The 24 engines of the outer ring kept firing, providing the thrust that would settle the Blok-B propellants and enable its own engines to ignite, whilst also giving a final boost to the rest of the stack. No previous N-1 launch had ever gotten this far, and it was here that the gremlins made one last roll of the dice.
The simultaneous shutdown of the six central Blok-A engines meant a sudden drop in thrust that sent a shockwave through the rocket. Joints were shaken and welds were strained, and deep inside the complex plumbing of the Blok-A propulsion system, pipes feeding oxygen and kerosene to the central engines snapped.
T+100 seconds.
Rocket propellant sprayed inside the aft compartment of the first stage and was quickly ignited on contact with the hot engine parts. A fireball expanded inside the aft compartment, continuing to be fed by the broken propellant lines.
T+105 seconds.
The fire suppression system, which was first added on vehicle 6L and had been upgraded for 7L, triggered and sprayed flame retardant chemicals into the compartment. The flames retreated briefly, but then resurged.
T+110 seconds.
A battle raged inside of Blok-A. A battle between flame and foam, and a battle against the clock. The outer engines felt the heat of the fire, and above them, the giant, almost-empty sphere of the oxygen tank got warmer, and warmer…
T+113 seconds.
With a burst of flame that dwarfed the events lower down, the eight NK-15V engines of Blok-B roared into life. Fourteen million Newtons of thrust hammered against the blast deflectors atop Blok-A’s kerosene tank.
T+118 seconds.
The fire in Blok-A finally reached the outer ring of engines. As engines started to fail, KORD began shutting them down in pairs, keeping the now-dwindling thrust balanced, before finally extinguishing all 24 engines. As the thrust dropped, the still-firing Blok-B separated from the doomed lower stage, pushing them apart a few seconds sooner than anticipated in their programming. The deviation is a minor one though, and as the heat of the fire finally ignites the vapours in Blok-A’s propellant tanks, the rest of N1-7L ascends, phoenix-like, to continue its journey into space.[2]
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[1] IOTL N1-6L launched on 26th June 1971, and failed for the same reasons. The earlier launch ITTL reflects the increased priority without the distraction of preparing for Salyut 1. Without full-scale ground testing (something ruled out by the cost of the necessary facilities), it was impossible to foresee the aerodynamic instabilities that doomed the rocket.
[2] The fire happened as described IOTL on launch 7L, but is believed to have been joined by the explosion of a turbopump on one of the still-firing NK-15s, probably due to contact between the turbine blades and the pump casing. ITTL additional attention to quality - or perhaps just dumb luck - mean that the turbopump explosion doesn’t happen, giving just enough of a window for Blok-B staging to complete before Blok-A ceases to function.
