The Ireland Neptune was a four or five place pusher configuration biplane sold in flying boat and amphibian versions. Designed in the U.S. and first flown in 1927, well over 50 were built.

Design and development

Ireland N-1B Neptune 3-view Aero Digest June 1927

Ireland N-2C Neptune Aero Digest March,1930

The Neptune was a

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

with a single, pusher configuration engine mounted just under the upper wing and with a conventional

hull Hull may refer to: Structures * Chassis, of an armored fighting vehicle * Fuselage, of an aircraft * Hull (botany), the outer covering of seeds * Hull (watercraft), the body or frame of a ship * Submarine hull Mathematics * Affine hull, in affi ...

. The 1927 type N-1B was initially advertised with engines in the power rang and an early 3-view shows it with an inline engine, but it first flew in late 1927 with a Wright J-5-C radial. About five more of this

flying boat A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in that a flying boat's fuselage is purpose-designed for floatation and contains a hull, while floatplanes rely on fusela ...

sub-type were built but, despite the 220 hp Wright, they were underpowered when loaded and so most were re-engined into N-2Bs. This was also a flying boat. It had a

Wright J-6-9 The Wright R-975 Whirlwind was a series of nine-cylinder air-cooled radial aircraft engines built by the Wright Aeronautical division of Curtiss-Wright. These engines had a displacement of about and power ratings of . They were the largest memb ...

but was otherwise similar to the N-1B. The N-2C which followed it into production was an amphibian and had a further 50% power increase from its heavier

Pratt & Whitney R-1340 Wasp The Pratt & Whitney R-1340 Wasp is an aircraft engine of the reciprocating type that was widely used in American aircraft from the 1920s onward. It was the Pratt & Whitney aircraft company's first engine, and the first of the famed Wasp series ...

. The power increase required a new, three-bladed propeller in place of the earlier, , 2-bladed one used by the N1-B and it had a swept upper wing and a increase of lower span. The Neptune was an unequal span single bay biplane with its lower wing on top of the hull and close to the water but with a wide interplane gap. The lower wing had a span 85% of the upper and was significantly narrower, but only it carried dihedral. The wings were rectangular in plan out to rounded tips apart from a central cut-out in the upper trailing edge for propeller rotation. Frise-type, Alcad covered ailerons were fitted only on the upper wings. Both wings were built around spruce

spars The United States Coast Guard (USCG) Women's Reserve, also known as the SPARS (SPARS was the acronym for "Semper Paratus—Always Ready"), was the women's branch of the United States Coast Guard Reserve. It was established by the United States ...

and were fabric covered and braced together by pairs of outward-leaning parallel interplane struts. The upper centre-section was mounted over the hull on a pair of sturdy N-form struts which were also the main engine supports. Leading edge sweep on the N2-C was about 7°. The hull had a Cr/Mo steel tube structure which was Alcad clad. The planing bottom had a shallow V-section and a single step under the wing, though it ended abruptly mid-way between wing and tail. Stability on the water was provided by small floats mounted below the interplane struts. The first few N-2Bs had open cockpits but most had glazed cabins like that of the N-1B, as did the N-2C. Crew and passengers were accommodated in two rows of side-by-side seats with the pilot's seat, on the front row, well ahead of the upper leading edge. Entry was via upward-opening doors Behind the wings the hull tapered to a conventional tail. Its fin was broad and tetrangular in profile, carrying a large

balanced rudder Balanced rudders are used by both ships and aircraft. Both may indicate a portion of the rudder surface ahead of the hinge, placed to lower the control loads needed to turn the rudder. For aircraft the method can also be applied to elevators and ...

. A small, near-rectangular tailplane was mounted on top of the fin, braced by inverted V-struts to the hull. The elevators were larger and balanced, separated by a cut-out for rudder movement. The tailplane was structurally similar to the wings but the other tail surfaces had metal frames. All were fabric-covered. The amphibious N-2C had mainwheels on short oleo strut legs close to the hull sides with rear drag struts and an oleo tailskid at the extreme rear fuselage. Wheel retraction was manual and took about 30 seconds.

Operational history

About 46 flying boats and 10 amphibians were completed, though histories are sparse. Two at least were used by Curtiss Flying Services, an air-taxi service, the first from mid-winter 1927-8 along the New England coast joined by another based in Florida a year later.

Variants

''Data from'' Aerofiles ;N-1B Neptune: 1927 four seat amphibian with a 9 cylinder

Wright J-5 The Wright R-790 Whirlwind was a series of nine-cylinder air-cooled radial aircraft engines built by Wright Aeronautical Corporation, with a total displacement of about and around . These engines were the earliest members of the Wright Whirlwin ...

. About six built. ;N-2B Neptune: 1928 five seat flying boat with a 9 cylinder

. About 40 built. ;N-2C Neptune: 1929 five seat amphibian with a 9 cylinder Wasp C. 10 built. ;N-2D Neptune: 1929 = 300hp

Wright J-6 The Wright Whirlwind was a family of air-cooled radial aircraft engines built by Wright Aeronautical (originally an independent company, later a division of Curtiss-Wright). The family began with nine-cylinder engines, and later expanded to inc ...

pusher. ;ND-5: 1929 - 5pCBAm; 450hp Wasp pusher. ;ND-6: 1929 - ND-5 with 300hp

pusher.

Operators

; Curtiss Flying Services

Design and development

Operational history

Variants

Operators

Specifications (N-2C)

Notes

References

Further reading