N1

The N1 was 105 metres long and 17 metres across at the base, with 95 tonnes of payload to low Earth orbit on paper. RussianSpaceWeb’s overview page gives liftoff thrust as 4,500 tonnes, about 44,130 kilonewtons, while its page on the Block A first stage gives 4,590 tonnes at sea level, about 45,013 kilonewtons. The overview figure is used here. It has no firsts listed because it never achieved anything: it did not once reach orbit.

Its first stage carried thirty NK-15 engines. The problem was not the number of engines, it was that RussianSpaceWeb states plainly what nobody could get around: the size of the stage prevented test firing of a fully integrated booster with all its engines, leaving it to actual flights to hammer out any issues during joint operation. Thirty engines whose interactions were only ever discovered at full scale, on the pad, in public, four times.

The system meant to contain that risk destroyed the first vehicle. KORD monitored four parameters on every engine across all three stages and could shut down any engine showing signs of catastrophic failure. On 21 February 1969, 0.34 seconds after liftoff, it issued a faulty command shutting down engine number 12. At 68.7 seconds it shut down all 28 remaining engines, after a 25 volt signal, ten volts over the allowable current, travelled across the whole KORD network.

The second attempt, on 3 July 1969, is the one that entered legend. A turbopump exploded a fraction of a second before liftoff, the vehicle rose about 200 metres, KORD shut down everything except engine 18, and it fell back onto the pad at about 23 seconds. It is often called the largest non-nuclear explosion in history, and it was not: roughly 85 percent of the propellant did not detonate, putting the yield nearer 4.5 to 5 tonnes of TNT equivalent rather than the theoretical 400 tonnes. Nobody was killed.

Two more flew and failed, in June 1971 and November 1972, and the Soviet lunar programme was cancelled in May 1974. The vehicle is worth keeping on this page precisely because it failed. Saturn V worked partly because NASA test-fired a bomb inside a running F-1 engine to see if it could recover. The N1 was never allowed the equivalent, and the difference between the two programmes is largely the difference between what each one could afford to break on the ground.