Bristol Type 123

Bristol Type 123

Company type	Prototype fighter aircraft
Industry	Aerospace
Founded	1934
Headquarters	United Kingdom
Products	Fighter aircraft

The Bristol Type 123 was a single-seat, single-engine biplane fighter developed in response to a United Kingdom Air Ministry specification during the early 1930s. Only one prototype was constructed.

Development

Towards the end of 1931, the Air Ministry issued specification F.7/30, which called for a four-gun fighter featuring enhanced high-altitude capabilities and endurance compared to existing aircraft, alongside superior climb performance, agility, excellent visibility in all directions, and a low landing speed. The specification indicated a preference for the evaporatively-cooled Rolls-Royce Goshawk engine. Among the designs submitted to meet this requirement, the most notable was the crank-winged Supermarine Type 224 monoplane with an open cockpit and fixed landing gear, designed by R.J. Mitchell. Bristol proposed several biplane concepts that did not secure prototype orders but were invited to develop a private venture aircraft.

This led to the creation of the Bristol Type 123, Bristol’s final biplane design, characterized by its compact and distinctive look along with advanced control systems. It was a single-bay biplane featuring wings of nearly constant chord extending almost to the tips and marked by pronounced stagger. The upper wings were swept without dihedral, while the cantilever lower wings were unswept with a dihedral angle of 6°. Both wings were equipped with full-span ailerons. Additionally, the upper wing incorporated full-span leading-edge slots divided into inner and outer sections. Ailerons were connected to interceptors positioned behind the outer slots that deployed when the inner slots opened at high angles of attack; simultaneously, the ailerons drooped symmetrically. This slot and interceptor arrangement aimed to prevent stalls from developing into spins and had previously been evaluated by Handley Page on a de Havilland Moth and subsequently by Bristol on a Bristol Bulldog. The rudder and elevators were horn-balanced, with trim tabs fitted on the elevators. The wings, tail assembly, and fuselage aft of the cockpit were fabric-covered over metal frameworks.

The aircraft’s pronounced stagger combined with its narrow nose gave it a somewhat humpbacked silhouette, with the pilot’s open cockpit positioned high above the centre of the lower wing and well behind the upper wing’s trailing edge. Armament consisted of twin pairs of machine guns mounted on either side of the engine. The fixed undercarriage was almost entirely enclosed in streamlined fairings that projected forward, joined by a cross-axle between the wheels.

Powered by an Air Ministry loaned Goshawk III engine, which utilized condensers integrated into the leading edges of the lower wings along with an additional ventral condenser mounted forward for cooling, initial flight attempts were delayed due to cooling issues. The first flight occurred on 12 June 1934 with test pilot Cyril Uwins at the controls. Flight testing uncovered significant lateral instability that persisted despite multiple modifications to the fin, rudder, and inner slots; this problem may have been related to structural factors. Consequently, further development was discontinued.