The Napier Lion was a long-lived and reliable engine family whose later versions powered the Supermarine S.5 and Gloster IV racers as well as a British Power Boat Company 63-foot Type 2 high-speed rescue launch. The Blackburn used the 450-horsepower Lion IIB rather than the roughly 480-horsepower standard form described in the video. Its lower output reflected navalization for repeated operation around salt water. Corrosion resistance, material choices, and maritime reliability therefore mattered more than extracting the maximum headline power.
Notable Point · 30:12-32:55
The navalized Napier Lion traded power for durability
The Blackburn's 450-horsepower Lion IIB sacrificed output so its materials and construction could withstand salt-water service.