Country of origin:

United States of America

Description:

Twin-engine commercial flying boat

Power Plant:

(Model 9)

Two 336 kw (450 hp) Pratt & Whitney SC-1 nine-cylinder air-cooled radial engines

Specifications:

History:

The Dolphin was designed by the Douglas Aircraft Company to meet the requirements of civil operators for a twin-engine flying boat, and the prototype, initially known as the Sinbad, flew for the first time at Santa Monica Bay, California, in July 1930. At the time it was fitted with two 224 kw (300 hp) Wright J-5C Whirlwind radial engines. Built initially as a flying boat, the advantages of amphibious capability were soon realised and the beaching gear was re-designed to form a undercarriage suitable for land-based operations.

Although the design had some potential on the civil market, it did not sell well, particularly because of its introduction during the Great Depression, and only 59 examples were built for civil operators, the remainder going to the United States Armed Forces. Construction numbers were not consecutive as aircraft were only built to fulfill orders, and a number of model numbers were allotted. Engines in the 224 kw (300 hp) to 410 kw (550 hp) range were installed.

The first series was the Model I, which accommodated two pilots and 8 to 10 passengers. The Model 3 was identical except it had two Pratt & Whitney R-985 Wasp Junior engines. Other models in the series followed up to the Model 9 in 1933, this having 336 kw (450 hp) Pratt & Whitney CD-450 Wasp engines, although the supercharged S3D1 model of the engine was also available. Last variant was the Model 10 with 373 kw (500 hp) Pratt & Whitney SD-1 radial engines.

Civil customers included William Wrigley, the chewing gum millionaire, who used a number of examples in the Los Angeles area; William E Boeing of the Boeing Aircraft Company (c/n 1280); and William K Vanderbilt, who purchased two Models 5s (c/ns 1283 and 1284), one usually being carried on the stern of the Vanderbilt yacht.

In US military service the type received a number of designations, these varying usually with the engines and equipment fitted. These included the RD-1, RD-2 and RD-4 with the US Coastguard; the RD-1, RD-2 and RD-3 with the US Navy; and the YIC-21 (later C-21), YIC-26 (later C-26), YIC-26A (later C-26A), C-26B, C-29, OA-3, OA-4, OA-4A, OA-4B, OA-4C, FP-2 and FP-2A with the US Army. These designations related to the type of duties the aircraft performed, OA relating to observation amphibians; C to transports; FP to frontier patrol; RD to Douglas transports.

Four are known to have operated in this region. N14286 (c/n 1282) was built for Standard Oil Company of New Jersey in 1934 and was transferred to the company’s Australian subsidiary, Australasian Petroleum Corporation in October 1939, operating alongside a Sikorsky S-38 amphibian and a Stinson Reliant floatplane. After service in New Guinea it was presented to the Royal Australian Air Force (RAAF) and flown to the Seaplane Training Flight at Rathmines, NSW becoming A35-1. It also saw service with No 9 Squadron. In September 1941 it was allotted to the workshops at Rathmines for a complete overhaul but this was never completed and in July 1943 approval was given for conversion to components.

The next aircraft was NC12212 (c/n 1002) built for William Wrigley as a Model 1. It is believed it operated with Australasian Petroleum Corporation in New Guinea during 1939 alongside N14286. It was presented to the RAAF as a gift but records indicated it was awaiting erection at Richmond, NSW in August 1941. In any event, it appears to have become A35-2 and served with the Seaplane Training Flight at Rathmines. On 8 October 1941 the mainplane was badly damaged when it ground-looped. It was repaired and issued to No 9 Squadron. On 27 July 1942 it suffered an engine failure and force landed at Fullerton Cove in the Port Stephens area but returned to Rathmines. Corrosion was repaired at No 2 Flying Boat Repair Depot (FBRD) at Rathmines and it returned to No 9 Squadron. On 12 December 1943 it was destined for another overhaul at No 2 FBRD but this was not completed and it was eventually converted to components in February 1944.

Dolphin 114 NC14204 (c/n 1279) was built with 410 kw (550 hp) Pratt & Whitney Wasp SC-1 engines for William Wrigley and operated with his Wilmington – Catalina Island Airline. It to came to Australia for use by the RAAF and became A35-4 with No 1 Service Flying Trining School (SFTS) at Point Cook, VIC and then No 3 Operational Training Unit (OTU). It operated with No 4 Communications Flight and No 9 Squadron until 29 July 1943 when it suffered hydraulic problems landing at Rose Bay and received damage. It was inspected by No 2 FBRD but later converted to components.

Dolphin NC982Y (c/n 1001) was a Model 3 with Pratt & Whitney Wasp Junior A engines built for Powell Crosley Jr and used by Crosley Radio Company. It was purchased for the RAAF and test flown at No 1 SFTS at Point Cook on 17 November 1942. It became A35-3 and went to No 9 Squadron at Point Cook. It also served with No 3 OTU. It was sold by the Commonwealth Disposals Commission to Mr M Whittle, at this time having Pratt & Whiteny Wasp Junior SB1 engines. He proposed to convert it for civil operations, to be based at Mascot, NSW and the registration VH-AGE was allotted. In May it was flown from Rathmines to Mascot and a new company Newcastle Safety Airways was formed by Stuart F Doyle Enterprises to charter the aircraft from Whittle.

However, a Certificate of Airworthiness was not forthcoming and an application was made to ferry the aircraft to Essendon, VIC for civil conversion. This was also rejected. Another possible buyer indicated an intention to use the aircraft on passenger services between Gladstone and Heron Island in Queensland but this also did not come to fruition. Sydney aviation identity Sid Marshall then sought to obtain the machine for possible freight operations and joy-riding, but its use would only be permitted for freight or private flying, subject to satisfactory performance flight testing. The Department advised a Certificate of Airworthiness would not be issued as it was concerned with various aspects of airworthiness and performance, particularly the aircraft’s ability to fly on one engine. In the end the registration was not taken up and the machine was left parked in the open at Mascot for several years until it was scrapped.

One airworthy Dolphin has survived in the United States, this being a Model 8 NC14205 (c/n 1230) once owned by William Boeing, which has been operated out of a private strip in Lexington, South Carolina.