R-7 Semyorka

The figures here are for the 8K71PS, the stripped R-7 that launched Sputnik, because that is the configuration with a payload to quote. NASA gives its length as 29.167 metres, almost four metres shorter than the ICBM version, after the warhead, the measurement hardware, the vibration monitoring and a 300 kilogram radio package came off it. Encyclopedia Astronautica puts liftoff thrust at 3,886 kilonewtons; RussianSpaceWeb prints 396.9 tonnes of thrust at liftoff, which works out at 3,892 kilonewtons. Two sources arriving within a fifth of a percent of each other is as firm as this gets. The core is 2.99 metres across, and the four strap-on boosters give the base a span of 10.3 metres.

The strap-ons are not there for thrust. They are there because in 1953 nobody knew how to reliably light a rocket engine already in flight. After considering around sixty designs, Korolev’s engineers chose to cluster four short boosters around a taller core and ignite all five on the pad, letting the core keep burning after the boosters fall away. Some called it a one and a half stage rocket. Every Soyuz that lifts off today still lights all five engines on the ground because of that workaround.

Sputnik 1 was the fallback, not the plan. Static testing showed the R-7 engines would not deliver more than 304 seconds of specific impulse against a projected 309 to 310, too little for the heavy Object D science satellite. Korolev asked why not launch something simpler first. He also had to threaten to take the whole question to the Central Committee before the state commission would let him try at all, on the reasoning that nobody in the room wanted to be blamed for missing a national first.

As a weapon it was a failure on its own terms. It burned cryogenic oxygen, took hours to prepare, and could not sit on alert, which is the only thing an intercontinental missile is for. Officially in armaments from January 1960, it was superseded within a few years. As a launch vehicle it became the most-flown orbital rocket family in history, and the reason is the same conservatism that made it a bad missile: nothing about it needed to be clever.

On 4 October 1957 at 22:28:34 Moscow time it put 83.6 kilograms of polished aluminium into orbit and rearranged the politics of the next two decades. A month later, on 3 November, the same vehicle carried the dog Laika, and that was the second and last flight of the 8K71PS. The dates on this record run from the first R-7 launch on 15 May 1957 to that second Sputnik; the missile itself stayed in armaments into the mid-1960s and its descendants have never stopped flying. Korolev, who once lost his temper at a workshop hand over the finish on a mockup, had been right about one thing: the ball did end up in museums.