The Loening M-8 was a monoplane fighter that was ordered into production in large numbers during the First World War, but that was eventually produced in significantly smaller numbers for the US Navy.
The M-8 was designed by Grover C. Loening, a very able aeronautical engineer who had graduated from Columbia University in 1911 after virtually writing his own course! Over the next few years he worked for the Wright Brothers, served as the chief engineer for the Army Flying School at San Diego and then as chief engineer for the Sturtevant Aeroplane Company. In 1918 he formed his own company, and one of his first commissions was to design a two-seat scout for the US Army that was to out-perform the Bristol Fighter. It was to be based around a 300hp Wright-Hispano Model H engine, and the first two prototypes were officially ordered as engine test beds for Wright-Martin.
Loening produced a shoulder-winged monoplane, an unusual design in a period when Allied aircraft design was almost entirely dominated by biplanes (although the same wasn't true in Germany where a number of monoplanes entered service during 1918, including the Fokker D.VIII).
Loening produced a monoplane with shoulder-mounted wings. The upper surface of the wings was level with the top of the fuselage and with the two open cockpits. The two crewmen thus had excellent upwards visibility. Downwards visibility was improved by installing cut-out windows in the side of the fuselage below the wing.
The wings were supported by twin struts that went from the bottom of the fuselage to a point half-way along the wing. The struts were given fairings with an aerofoil cross-section, and it was hoped that they would thus provide some lift.
One novel feature that was used in many later aircraft was the location of the radiator. In many aircraft of this period the radiators were bolted on to the outside of the fuselage or the wings, or were carried around the propeller shaft. On the M-8 the radiators were carried in a tunnel built into the part of the fuselage below the engine.
The aircraft was of wooden construction, with a fabric covering. It was quite light and was able to carry two 0.3in Lewis guns on a flexible mounting in the observer's cockpit. The M-8 was significantly faster than the Bristol Fighter. Its performance impressed the Army, and an order for 5,000 aircraft was placed.
This order was cancelled after the end of the First World War, but the US Navy then expressed an interested in the design. They had already purchased three Loening Kittens, a light-weight aircraft designed for use from submarines and now decided to order the M-8 as a full sized fighter. A single prototype was ordered, with the designation M-8-0. This was followed by forty-six land planes, which were given the designations M-8-0 and M-8-1, and by six M-8-1S floatplanes. The Naval Aircraft Factory built thirty six of the aircraft, Loening built the rest.
The Navy's M-8s were ordered as fighters, but they were used as observation aircraft. One was modified for use as a racer, and was entered into the 1920 Pulitzer race but was forced to withdraw by a water leak in the cooling system. The Army resumed its interest in the type, and in 1920 ordered prototypes of a modified single-seat fighter, the Loening PW-2.
The two prototypes ordered by the Army had the designation M-8.
The M-8-0 was the designation given both to the prototype ordered by the Navy and some of the production aircraft.
The remaining Naval production was given the designation M-8-1.
The M-8-1S was a floatplane version of the M-8-1,
As well as the M-8-1S the US Navy ordered three seaplane versions of the M-8, with the designation LS-1 (Loening Seaplane 1). Only one of these three aircraft was completed, and the single aircraft was used to test the Richardson Pontoon. This was a twin float design with vertical inside surfaces (resembling one large float that had been cut in half). The idea was that the straight edges would improve the water handling of the aircraft. The idea doesn't seem to have been developed any further.
Statistics for M-8-0
Engine: Wright-Hispano Model H engine
Span: 32ft 9in
Height: 6ft 7in
Empty Weight: 1,623lb
Gross Weight: 2,068lb
Maximum Speed: 145mph
Climb rate: 10 minutes to 13,900ft
Endurance: 5.5 hours
Guns: Two flexibly mounted 0.30in Lewis gun