Nakajima P-1 type night-mail delivery plane, 1934.

Nakajima P-1 type night-mail delivery plane, 1934, on a test flight past Mount Fuji. The airplane’s initial open cockpits were later enclosed to better protect the pilot flying at night through inclement weather conditions.

“The Nakajima P-1 was based on the Nakajima E4N2 (Navy Type 90-2-3), a reconnaissance seaplane constructed of mixed wood and metal structure with fabric covering which first entered production for the Imperial Japanese Navy in 1931.

“In 1933, Nakajima won a contract from Nihon Koku Yuso (Japan Air Transport Co.) to convert nine E4N2-C airframes into single-seat land-based P-1 mail planes to be employed on night-mail services between the Japanese Home Islands.

“Aside from certain external structural changes (e.g. replacing floats with fixed landing gear), other modifications included replacing the original Nakajima Kotobuki 2 581 hp nine-cylinder engine with the 420–450 hp Nakajima Jupiter VI nine-cylinder engine or, later, the 585 hp Nakajima Kotobuki 2-kai-1 nine-cylinder radial engine.

“Its cockpit was initially open but enclosed on later aircraft with glazing running aft into a turtle back fairing. Night flight safety was increased by two landing lights under mid-span and the addition of parachute distress flares. It also had a radio receiver and a radio beacon.

“The first of Nihon Koku Yuso‘s eight P-1 aircraft was completed in May 1933. (A ninth, specially built P-1 was used exclusively by the Ministry of Communications.) The standard night mail route connected Tokyo, Osaka and Fukuoka and began operations in August 1933.

“The service was successful in the sense of increasing mail volume. But, it showed that night flights were stressful for a single flyer piloting a single-engined aircraft, especially in bad weather. As a result, the P-1s were gradually retired over two pioneering years, replaced by larger, twin-engined aircraft with a larger crew.”

– Wikipedia

Nakajima P-1 type mail delivery plane, 1934.

Nakajima P-1 Performance

Maximum speed: 243 km/h (151 mph, 131 kn)
Cruise speed: 194 km/h (121 mph, 105 kn)
Range: 1,000 km (620 mi, 540 nmi)