RD-108
Core stage engine of the R-7
On display
The RD-108 differs from its strap-on sibling in having more vernier chambers — four instead of two — and a tuning for longer operation: the core stage keeps accelerating after the boosters separate, so the nozzles are optimised for thinner air.
A cluster of one RD-108 and four RD-107s gives about 4 meganewtons of thrust at lift-off. All twenty chambers ignite simultaneously on the ground: in-flight ignition of such a cluster would be an unjustified risk.
On display is a sectioned engine showing the turbopump assembly, the gas generator and the chamber cooling passages.
