Yokosuka E1Y (1923)

IJN Multirole Observation seaplane 1924-1937

The Yokosuka E1Y was a Japanese observation floatplane of the twenties, one of the first. It was single-engined, designed and developed by the Yokosuka Naval Air Technical Arsenal for the Imperial Japanese Navy. With 320 built as the Type 14 Reconnaissance Seaplane, entering service in 1925 it remained one of the main reconnaissance types until gradually replaced from 1932, but still in service until 1937. It found use from all Cruisers and IJN Battleships of that era and fought in China, notably from IJN Notoro.

Type 14 or Yokosuka E1Y-3 from IJN Hyuga (background) taking off c1936src

Design of the E1Y

Development

In 1919-1920 the Imperial Japanese Navy had grand plans of expansion, and did not lost any bit of the advantages presented by aircraft in WWI. In fact the country even was the first to deploy a seaplane carrier in combat, in 1914. This was IJN Wakamiya, a reconverted cargo, which operated a single seaplane in the siege of Tsingtau (German naval base and colony in China). This showed also that seaplanes had a massive potential to provide reconnaissance for the fleet, which naval plans were in full swing. So right before the Washington treaty, the IJN naval staff wanted 300+ seplanes of a single standard model for everything from reonnaissance, observation and spotting, providing a radio could be fitted.

In 1921, the Japanese Naval Arsenal at Yokosuka, the state center in which skilled engineers worked out new designs for the Navy, started work on a single-engined reconnaissance floatplane. Initially this was to replace the now obsolescent Yokosuka Ro-go Ko-gata, in service from 1918 (218 made). The result was called the Type 10 Reconnaissance Seaplane. The design team was composed of members of a delegation sent to Short Brothers, UK. This was a single-engined two-bay, two-seat biplane. It had a 400 hp (298 kW) Lorraine-Dietrich engine which was to be built under licence.

E1Y variants: Top E1Y-1, bottom E1Y-2

The first two prototypes were completed in 1923, showing however poor performance. It was soon established they were overweight and a completely modified Type 10, called the "Model A", flew in 1924. There was some improvement, and the model B, a new prototype, flew in 1925. It was much lighter while being more stable and easier to fly overall. It was chosen to be built as a pre-serie. Though, the Type 10 was not adopted by IJN which estimated more could be done.

In its fourth redesign the wingspan was shortened from 16.16 m (53 ft 0¼ in) to 13.99 m (45 ft 11 in) and weight was again cured down from 1,912 kg (4,215 lb) to 1,660 kg (3,659 lb), making the best of their engines. First trials showed great promises and as revised it was accepted for production in January 1926 as the Type 14. In the Navy it was standardized as the E1Y. A total of 218 E1Y1/E1Y2s were built. Only a few by Yokosuka (23), 47 by Nakajima and 148 by Aichi which also manufactured 102 E1Y3s, the ultimate variant.

Characteristics

E1Y3 (Type 14)

Two main versions entered service in 1926 (and many variants, see below).
-A two-seater with a 400 hp (300 kW) Lorraine-Dietrich 1 V-12 engine, called Type 14-1/E1Y1
-A three-seater with all-metal floats and the Lorraine-Dietrich 2 W engine called Type 14-2 or E1Y2.

In 1928, the same became the basis for the new Type 90-3 Reconnaissance Seaplane, 20 built as the Yokosuka E5Y1 and the Kawanishi E5K1. It showed only minor improvement over the Type 14-2 so in 1931, Yokosuka developed the new 14-3, sporting a new tail, a more powerful, geared Lorraine-Dietrich 3 engine. Performance increased across the board.

The E1Y2 was 10.59 m (34 ft 9 in) long for a wingspan of 14.22 m (46 ft 8 in), 4.15 m (13 ft 7 in) high and a total wing area of 54.2 m2 (583 sq ft). This was a big plane, yet relatively light, being 1,889 kg (4,165 lb) empty, 2,750 kg (6,063 lb) gross. It was powered by the same powerful Lorraine 2 W-12 water-cooled piston engine which developed 336 kW (451 hp). This was a French engine developed as the Lorraine 12E Courlis. It was also built in Spain and Poland. The first version ran in 1922. It was liquid cooled but with a very peculiar arrangement in W-12 or broad arrow, with three rows of cylinders, one axial, two angled. A reliable and powerful engine, it was adopted by more than 30 aircraft.

Despite the bulk and large wings and fuselage, the EY2 was "only" capable of 178 km/h (111 mph, 96 kn) for a cruise speed of 130 km/h (81 mph, 70 kn). it was not able to escape fighters, but certainly had a better range at 1,156 km (718 mi, 624 nmi) or up to 9 hours flight, perfect for the fleet. It could observe opposite fleets from 4,000 m (13,000 ft), out of AA fire envelope, but had a slow cimbing rate of 3,000 m (9,800 ft) in 28 minutes 13 seconds, and an abysmal extra time to reach 4,000 m. Its wing loading was 50.7 kg/m2 (10.4 lb/sq ft) explaining the still large wingspan, and it had a power to mass ratio of 0.1226 kW/kg (0.0746 hp/lb).

The construction called for metal only for the forward engine and fuel tank wrapping, then metal tubing and wood paneling for the fuselage, wooden and metal framing for the wings, tail and rudder, wrapped in canvas. The crew of three comprised the pilot, the radio/observer behind sharing the same cockpit and the gunner a bit further aft the fuselage in his own seat. The "14 Shiki" also had a wooden four-bladed propeller. The E1Y2 floats were all metal and shorter but wider compared to the E1Y1s wooden and metal floats. But they were installed the same. The equal plan wings were braced and connected by two pairs of I type struts with a nother pair at the middle of the wings, over the pilot. The floats were connected by N types struts to the lower fuselage with two pairs connected to the underwings base.

Being a primary observation seaplane, the E1Y could only carry so much armament, a single flexibl mount with a 7.7 mm machine gun aft, nothing for the pilot. It could also carry a small bomb payload under the lower wings, close to the fuselage under racks, two 110 kg (240 lb) or four 30 kg (66 lb) bombs. This model was occasionally used for harrasment missions in China at the very end of its service.

Variants

Navy Type 10 Reco Seaplane: Prototype, 400 hp (298 kW) Lorraine-Dietrich 1 V-12 (2)
Navy Type 10 Model A: Revised prototype (1)
Navy Type 10 Model B Same, plus 5 pre-prod.
Navy Type 14-1 (E1Y1): Production version, same engine.
Navy Type 14-2 (E1Y2): Modified prod. metal floats, 450 hp (336 kW) Lorraine-Dietrich 2 W
Navy Experimental Type 14-2 Kai-1: Based on the Type 14-2
Navy Type 14-3 (E1Y3): New tail, better performance.
Navy Type 14 Modified Transport Seaplane, Civilian adaptation

The D1Y in action

The E1Y1 and E1Y2 entered service in 1926, replacing as intended the mush slower Ro-Go Ko-Gata as well as the Hansa-Brandenburg W.33 seaplanes also in service. The last E1Y3 also arrived in units from 1931, produced by Aichi. The E1Ys became the main reconnaissance seaplanes of the fleet, and operated as much from battleships than seaplane tenders. In the former role, they acted as spotters, in the latter, as reconnaissance models. E1Ys were operated notably from the transformed seaplane tender Notoro and they proved indstrumental to provide intel to IJA and SNLF troops in the 1932 Shanghai Incident.

In fact some were used to strafe and bomb Chinese troops as well. The E1Y remained in use until the Second Sino-Japanese War flared up in 1937 but most were retired already from 1933-34, replaced by more modern models, and many also were resold t the civilian marketn being used for transport, converted with an enclosed cabon and four seats. They served practically up to WW2, refitted with more powerful Napier Lion engines.