The P.1127/Kestrel was an experimental V/STOL aircraft, which served as the forerunner for the production of the Hawker Siddeley Harrier and the wider Harrier Jump Jet family.
It served to demonstrate an entirely original technique of flight, as well as to trial a brand new type of engine in the form of the Pegasus turbofan engine.
Despite this, the aircraft employed a principally conventional structure which, according to Mason, lent itself favourably to performing the intended ground attack operations envisioned for production aircraft.

The location of the large Pegasus engine, which was housed within the relatively small fuselage, meant that the cockpit was positioned directly forward of it, in between the later "elephant-ear" air intakes to the engine itself.
The 'cold' jet exhaust was directed from the large fan forward of the engine compressor to rotatable fiberglass nozzles located on the sides of the main fuselage aft of the air intakes; the 'hot' jet exhaust from the rear of the engine were channeled via a bifurcated exhaust channel to two steel rotatable nozzles located somewhat aft of those used for the 'cold' jets.
Additionally, bleed air was also extracted from the compressor and sent via ducts within the fuselage and wings to control nozzles, known as "puffers", located upon the aircraft's nose, tail, and wing tips, which were used for stabilisation during mid-air hovers.

The aircraft was furnished with a single-piece shoulder-mounted wing mounted across the top of the fuselage; the shape of the wing progressively alters from a clipped delta to a fully swept configuration, complete with extended leading edges and spaced out sawtooth extensions.
A fully movable single-piece tailplane was also adopted, which was hinged upon the rear fuselage.
The P.1127 had an atypical undercarriage arrangement, known as a "zero-track" tricycle undercarriage, which supported the majority of the aircraft's weight upon a pair of centrally mounted main wheels; steering was performed via a conventional nose wheel while balance was provided by a pair of wing tip-mounted outriggers.

The P.1127 was equipped with entirely conventional flying controls when operated within the normal flying regime; to avoid aerodynamic stall conditions when decelerating to slow speeds, control would be gradually and automatically transferred to the reaction jets, or "puffers", by bleeding more air from the compressor as the engine nozzles were moved towards the downwards position.
An auto-stabilisation system was installed upon all aircraft; the necessity of such a feature is arguable, as countless transitions between vertical and horizontal flight were performed with the auto-stabiliser equipment being entirely disabled.

The P.1127 lacked any in-built armaments, the ethos of tactical flexibility meant a reliance upon underwing hard point-mounted munitions and equipment, which included multiple 2-inch rocket batteries, 30-mm ADEN cannon gun pods, and 1,000 lb bombs, napalm, and range-extending drop tanks.
The prototypes were furnished with long nose-mounted instrumentation booms, these were replaced on the Kestrel with a much smaller counterpart on the fin to enable the nose to accommodate a tactical camera instead.
An unusual feature of the P.1127 was the installation of a ram air turbine upon the rear fuselage just forward of the fin to provide power for ancillary services in the event of engine failure.
The P.1127/Kestrel was an experimental V/STOL aircraft, which served as the forerunner for the production of the Hawker Siddeley Harrier and the wider Harrier Jump Jet family. It served to demonstrate an entirely original technique of flight, as well as to trial a brand new type of engine in the form of the Pegasus turbofan engine. Despite this, the aircraft employed a principally conventional structure which, according to Mason, lent itself favourably to performing the intended ground attack operations envisioned for production aircraft.
The location of the large Pegasus engine, which was housed within the relatively small fuselage, meant that the cockpit was positioned directly forward of it, in between the later "elephant-ear" air intakes to the engine itself. The 'cold' jet exhaust was directed from the large fan forward of the engine compressor to rotatable fiberglass nozzles located on the sides of the main fuselage aft of the air intakes; the 'hot' jet exhaust from the rear of the engine were channeled via a bifurcated exhaust channel to two steel rotatable nozzles located somewhat aft of those used for the 'cold' jets. Additionally, bleed air was also extracted from the compressor and sent via ducts within the fuselage and wings to control nozzles, known as "puffers", located upon the aircraft's nose, tail, and wing tips, which were used for stabilisation during mid-air hovers.
The aircraft was furnished with a single-piece shoulder-mounted wing mounted across the top of the fuselage; the shape of the wing progressively alters from a clipped delta to a fully swept configuration, complete with extended leading edges and spaced out sawtooth extensions. A fully movable single-piece tailplane was also adopted, which was hinged upon the rear fuselage. The P.1127 had an atypical undercarriage arrangement, known as a "zero-track" tricycle undercarriage, which supported the majority of the aircraft's weight upon a pair of centrally mounted main wheels; steering was performed via a conventional nose wheel while balance was provided by a pair of wing tip-mounted outriggers.
The P.1127 was equipped with entirely conventional flying controls when operated within the normal flying regime; to avoid aerodynamic stall conditions when decelerating to slow speeds, control would be gradually and automatically transferred to the reaction jets, or "puffers", by bleeding more air from the compressor as the engine nozzles were moved towards the downwards position. An auto-stabilisation system was installed upon all aircraft; the necessity of such a feature is arguable, as countless transitions between vertical and horizontal flight were performed with the auto-stabiliser equipment being entirely disabled.
The P.1127 lacked any in-built armaments, the ethos of tactical flexibility meant a reliance upon underwing hard point-mounted munitions and equipment, which included multiple 2-inch rocket batteries, 30-mm ADEN cannon gun pods, and 1,000 lb bombs, napalm, and range-extending drop tanks. The prototypes were furnished with long nose-mounted instrumentation booms, these were replaced on the Kestrel with a much smaller counterpart on the fin to enable the nose to accommodate a tactical camera instead. An unusual feature of the P.1127 was the installation of a ram air turbine upon the rear fuselage just forward of the fin to provide power for ancillary services in the event of engine failure.
Hawker Siddeley P.1127