When Pemberton-Billing Ltd changed its name to Supermarine Aviation in December 1916, work on a further airship fighter, the P.B.31E, had reached an advanced stage and the first prototype of this quadruplane was to fly shortly afterwards, in February 1917. Fundamentally an extrapolation of the P.B.29E, and unofficially known as Night Hawk, the P.B.31E was designed to have a maximum endurance in excess of 18 hours to enable it to lie in wait for intruding airships. The entire concept was fallacious as, in the unlikely event that the P.B.31E found itself fortuitously in the same area of sky as its prey, it would have been totally incapable of pursuing the airship which could have risen out of range before any guns could have been brought to bear. A three-bay quadruplane powered by two 100hp Anzani nine-cylinder radials, the P.B.31E carried a searchlight in the extreme nose. The intended armament comprised a one-and-a-half pounder Davis gun on a traversing mounting in a forward position level with the top wing, a 7.7mm machine gun being located in a second position immediately aft and a similar weapon occupying a forward fuselage position. Shortly after the start of flight trials, the shortcomings of the concept were finally appreciated, and, on 23 July 1917, the first prototype was scrapped and the second incomplete prototype abandoned.

3-View

A three-view drawing (1278 x 930)