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Napier Dagger


The Napier Dagger was FB Halford's most successful air-cooled engine design for Napier.  The 24-cylinder supercharged engine was of vertical 'H' configuration with twin crankshafts geared together. It included Halford patented hudraulic tappets operated from its four sets of single overhead camshaft gear  


Flight testing was carried out by Fairey's test pilot, Chris Staniland, in a Fairey battle.  Despite receiving the full support of the Air Ministry this engine failed to break into the market in a big way.  The engines were fitted in the Hawker Hector and the twin engined Handley Page Hereford light bomber which saw active service in Europe and North Atlantic early in WWII.


The Trust's Dagger is a crash victim believed to be an E105 Dagger 800 Series III.  It was either a test engine from a Fairey Battle, prototype Martin Baker II fighter or, more likely, from a Hawker Hector biplane army support light bomber.

Rocket Lion Javelin Culverin Sabre Rapier Cub Piston

'H' Air-Cooled Engine

Design E98   1934   Dagger I

24-cylinder 4.1/2" bore x 5.1/4" stroke  630 bhp


Design E105   1935   Dagger 800

24-cylinder 3.13/16" bore x 3.3/4" stroke  725 bhp


Design E108   1937   Dagger H10

24-cylinder 3.13/16" bore x 3.3/4" stroke  935 bhp


Design E110   1939   Dagger VIII

24-cylinder 3.13/16" bore x 3.3/4" stroke  1,000 bhp


Design E112   1939   Enlarged Dagger

24-cylinder 4.1/16" bore x 3.15/16" stroke

Where to see:

    NMSI Store, Wroughton, Nr. Swindon

    NPHT collection

    RAF Museum Hendon