|OA-1A San Francisco (26-431) of the U.S. Army Pan American Flight|
|Role||Amphibious observation aircraft|
|Primary users||United States Navy
United States Army Air Corps
First flown in 1923, the OL was a high-performance amphibian with a large single hull and stabilising floats fitted underneath each lower wing. The landing gear was retractable by use of a hand-crank in the cockpit, and the plane was equipped with a tailskid for operations on land. It had a tandem open cockpit for a crew of two. The aircraft could be flown from either cockpit, with a wheel control in the forward cockpit and a removable stick control in the rear. Navigation and engine instruments were located in the forward cockpit.
The hull was built of Duralumin on a wooden frame, with five watertight compartments connected through a selector switch to a bilge pump in the rear cockpit. Plugs in the bottom of each compartment permitted drainage on the ground. The fuselage was constructed on top of the hull. The aircraft was strength-tested at Columbia University.
The United States Army Air Corps ordered four prototypes as the XCOA-1, powered by a 400 hp Liberty V-1650-1 engine mounted inverted for clearance of the three-bladed variable-pitch steel propeller. The engine came with a fire suppression sprinkler system and was encased in a streamlined cowling to protect it from sea spray. Oil from a tank in the fuselage was cooled by passing through a spiral copper tube exposed to the slipstream on top of the cowling. The fuel tanks were mounted inside the hull, with a 140 gallon (530 liter) gasoline tank under the wings, and a reserve 60 gallon (230 liter) gasoline-benzol tank between the cockpits. Total fuel capacity provided for approximately ten hours of flight.
A number of variants were introduced for both the Army and United States Navy. During later production the company merged with the Keystone Aircraft Corporation.
- Four prototypes powered by 400hp V-1650-1 engines, three later to COA-1
- Three prototypes and nine production aircraft for the Army Air Service
- Army production aircraft with redesigned vertical tail and powered by a 420-horsepower, water-cooled Liberty V-12 engine that was mounted inverted, 15 built.
- One prototype with a single retractable mainwheel and skids fitted to wing floats. Powered by a inverted V-12 Wright Typhoon, redeignated OA-10 before delivery in 1929.
- Same as an OA-1A with a water-cooled V-1650-1 engine, nine built.
- OA-1B with redesigned fin and rudder, ten built.
- OA-1C with 480hp Wright IV-1460-1 engine modified tail surfaces and forward-firing machine gun moved to port upper wing, eight built.
- One XOA-1A redesignated before delivery by the U.S. Army.
- Naval version with third cockpit, two prototypes powered by a 440hp Packard 1A-1500
- Naval version similar to the COA-1, five built.
- OL-1 powered by a 475hp Packard 1A-1500 and other detail changes, four built.
- OL-3 powered by a 400hp V-1650-2 engine, six built.
- Three of these were built for the U.S. Coast Guard in 1926
- OL-3 with a redesigned vertical tail as OA-1C, 28 built.
- One OL-6 fitted with experimental thicker wing.
- One OL-6 re-engined with 450hp Pratt & Whitney R-1340-2 engine.
- As XOL-8 with two cockpits and a 450hp R-1340-4 engine, 20 built.
- An OL-8 fitted with arrestor gear, 20 built.
- An OL-9 with equipment changes, 26 built.
- An improved version of the OL-6, prototype only.
- A development of the OA-2 with a 200hp R-1340-0 engine, project cancelled.
- United States Army Air Corps
- United States Coast Guard
- United States Navy
- El vuelo pan americano de buena voluntad 1926-1927
Data from The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985), 1985, Orbis Publishing, Page 2376
- Crew: two
- Length: 34 ft 9 in (10.59 m)
- Wingspan: 45 ft 0 in (13.72 m)
- Height: 12 ft 9 in (3.89 m)
- Wing area: 504 ft2 (46.82 m2)
- Empty weight: 3649 lb (1655 kg)
- Gross weight: 5404 lb (2451 kg)
- Powerplant: 1 × Pratt & Whitney R-1340-4 Wasp radial piston engine, 450 hp (336 kW)
- Maximum speed: 122 mph (196 km/h)
- Range: 625 miles (1006 km)
- Service ceiling: 14,300 ft (4360 m)
- Aircraft of comparable role, configuration and era
- Related lists
- List of seaplanes and flying boats
- List of military aircraft of the United States
- List of military aircraft of the United States (naval)
- John Andrade, U.S.Military Aircraft Designations and Serials since 1909, Midland Counties Publications, 1979, ISBN 0-904597-22-9 (Page 98, 137 194 and 204)
- The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985), 1985, Orbis Publishing, Page 2376
- "Air Stations". Historic Coast Guard Air Stations. U.S. Coast Guard Historian's Office. Retrieved 22 December 2014.
- "Record of Movements, Vessels of the United States Coast Guard, 1790–December 31, 1933 (1989 reprint)" (pdf). U.S. Coast Guard, Department of Transportation.
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