The Development of the “H” Engine: The Latest Series of the Interesting Napier Rapier Described and Illustrated Available to Purchase

IT will be remembered that the salient features of the Napier Rapier engine were described in AIRCRAFT ENGINEERING, Vol. II, July, 1930, p. 166, while some brief particulars of the Scries II type appeared in Vol. IV, November, 1932, p. 281. D. S. Napier and Sons, Ltd., now send full details of the Series II and Series IV types, both of which have passed the Air Ministry 100 hours' Type Test. The two engines, which both have a 6·0 : 1 compression ratio, do not differ except that the Series II is rated at 305 b.h.p. at 3,500 r.p.m. at 10,000 ft., and the Scries IV at 340 b.h.p. at 3,500 r.p.m. at sea level.