D. Napier and Son began work on a remarkable new engine, the Lion, in 1916. Its three banks of four cylinders formed a "W" or "Broad Arrow" configuration. The arrangement provided a much shorter crankcase, a stiffer and simpler crankshaft, and a more compact engine than the 12-cylinder "V" construction of other high-performance engines of the period. Napier produced the reliable and widely used Lion series from 1917 until 1932 for military, commercial, and special-purpose racing aircraft.
This early version of the Napier Lion is believed to be a Model II or IIB. Napier manufactured these models from 1918 through 1925 to power many British aircraft types, including the Handley Page H.P.15 V/1500 bomber, Supermarine Sea Lion I racer, and the Felixstowe F.5 flying boat.
Transferred from the U.S. Navy, Naval Supply Center, Cheatham Annex, Williamsburg, Virginia.
Country of Origin: United Kingdom
Length 125.7 cm (49.5 in.), Width 106.4 cm (41.9 in.), Height 91.4 cm (36.0 in.)
Type: W-type, 12 cylinders, liquid cooled
Power rating: 336 kW (450 hp) at 1,925 rpm
Displacement: 24 L (1,462 cu in)
Weight: 389 kg (858 lb)
Manufacturer: D. Napier and Son, Ltd., London, England
Overhead cam; 2 carburetors, inertia starter, water pump, propeller hub; missing exhaust manifolds; on stand.