Heading into the 1920s, the United States Navy (USN) looked to a new, all-modern fighter type with a dual-role capability in mind. This single-seat, single-engine mount would be of standardized design for equipping a wheeled undercarriage for land-based service or twin floats for operating on water. In 1921, the requirement was fleshed out and the competition was open to both local aero-industry as well as those with wartime experience in Europe.
The British concern of Handley Page, founded back in 1909, responded with a modern monoplane of advanced design for the period. The fuselage was well-streamlined and incorporated the powerplant at the extreme front end of the design in the usual way with the open-air cockpit positioned just aft. The pilot sat behind a windscreen and ahead of a raised section of the dorsal spine to protect the head and neck from violent forces or rollovers. The fuselage tapered elegantly to the tail to which a high-reaching, large-area, single-finned rudder arrangement was set in place. The wing mainplanes were set low against the sides of the fuselage, though positioned nearly at the nose which drove center mass considerably forward. The undercarriage was a twin-wheeled, strutted arrangement under the nose with a skid installed at the underside of the tail. As stated, the aircraft would be able to swap out the wheeled undercarriage for twin floats for water landings. Construction was largely of wood with plywood skinning used at both the wings and fuselage.
The aircraft was planned from the outset to carry a 400 horsepower output engine through its serial production models but prototypes were powered by the lower-rated Gwynne (Bentley) BR.2 rotary engine of 230-232 horsepower used to drive the two-bladed propeller unit at the nose.
As with other fighters of the period, this monoplane would be capably armed through a pairing of machine guns in fixed, forward-firing mounts set over the nose and synchronized to fire through the spinning propeller blades. Based on the local USN requirement, these weapons were to be 2 x 0.30 caliber (7.62mm) Marlin Machine Guns (as opposed to the popular British Vickers used across European fighter designs).
Internally, the aircraft was known to Handley Page as the "Type S".
Three prototypes were contracted by the USN under the local designation of "HPS-1" (for "Handley Page Scout"). The first of these was readied and flown for the first time on September 7th, 1923 but its handling (particularly in the realm of directional stability) left something to be desired so various fixes were enacted in an attempt o resolve the issues. The second prototype was given an advanced mainplane form in which dihedral (upward angle) was six degrees. This model was tested beginning in February of 1924.
It was this prototype that, with a ballast added to simulate the required USN war load, hard-landed during evaluations, its undercarriage collapsing as a result. The accident more or less spelled the death knell for this monoplane program and third prototype, to feature the requisite twin floats, was never realized. The Type S became Handley Page's only attempt at a frontline fighter - the firm known largely for design and construction of oversized aircraft more suitable for the bombing role than one-on-one combat. In later literature, the Type S would be referred to as the "HP.21".
As completed, the stylish, racer-like aircraft had a running length of 21.5 feet, a wingspan of 29.2 feet, and a height of 9.6 feet. Empty was 1,320lb with a Maximum Take-Off Weight (MTOW) of 2,030lb. It managed a maximum speed of 147 miles-per-hour with a service ceiling of 21,000 feet and a rate-of-climb nearing 1,800 feet-per-minute. Flying endurance was up to three hours on internal fuel.