The Chow rocket motor was developed to provide the boost stage of theSea Dart SAM for the Royal Navy. The Chow is a tandem boost motor capable of boosting the Sea Dart to M2.5 in 4 seconds, enabling the Odin ramjet to operate.
Chow featured a quartet of boost fins, which are folded to reduce the size of the Sea Dart during stowage and loading, but flip out under G-force as the missile is launched. The fins are fully deployed as the missile clears the launcher.
The photograph shows a complete Sea Dart Drill round with Chow motor attached and is on display at the Bristol Collection at Kemble Airfield.