On 15 July 1960, the first "P.1127 Prototype V/STOL Strike Aircraft", serial XP831, was delivered to Dunsfold Aerodrome, Surrey, to commence static engine testing.
On 31 August 1960, the Pegasus engine was run for the first time while inside the airframe.
Some of the tests were performed from a purpose-built platform at the aerodrome which functioned to deflect the hot exhaust gases away from the aircraft during early hovering trials while more powerful versions of the engine were developed.
On 13 October 1960, the first Pegasus flight engine, capable of generating 11,300 lb of thrust, was delivered to Dunsfold.

On 21 October 1960, the initial tethered flight, performed by XP831, was conducted at Dunsfold; at this stage of development, this feat had required the airframe to have been stripped of all extraneous weight and restrictions on the engine meant it could not be run at full power for more than 2.5 minutes at a time.
Several tethered flights took place, partially so that the test pilots could familiarise themselves with the hovering controls; on 4 November, the first tethered flight without use of the auto-stabiliser system was accomplished.
In mid-November, conventional taxying trials were performed at speeds of up to 70 knots.

On 19 November 1960, the first un-tethered free-flight hover of XP831 was achieved; a week later, the first publicity photos of the P.1127 were released.
Prior to the first flight, Hooker is claimed to have asked of Camm "I suppose you are going to do some conventional flying first Sydney?"
and Camm replied "What for?"
 Hooker said "Well you know, just to make sure the aeroplane is a nice aeroplane, and everything under control."
 Camm replied, "Oh, Hawker aeroplanes are always beautiful, nothing wrong with a Hawker aeroplane, not going to bother with that.
Vertical first time".

On 13 February 1961, XP831 performed its first conventional flight, flown by Bill Bedford and lasting for 22 minutes.
Soon after this, XP831 was refitted with a new model of the Pegasus engine, capable of generating 12,000 lb of thrust, prior to embarking on new hovering trials in May 1961.
In June, XP831 attained another milestone in the program when it performed the first transition from vertical hover to horizontal flight, initially flying the length of Dunsfold's runway at a height of 50 meters.

On 7 July 1961, the second prototype, XP836, performed its first take off conventionally.
Continuing tests of the two prototypes proceeded to close the gap between vertical take off and flight, a feat which was achieved on 8 September 1961.
During September, the feat was repeated multiple times by both prototypes, transitioning from vertical to horizontal flight and vice versa, including instances in which the auto-stabiliser was intentionally disabled.

During the flight test program, the issuing of NATO Basic Military Requirement 3 (NBMR-3) did not prove to be the opportunity as envisioned by Hawker, as NBMR-3 sought performance characteristics of which the P.1127 was not only unable to meet, but unlikely to be developed to meet in its current form either.
As such, in 1961, there was little military interest in the P.1127 program, although, in January 1961, Hawker was requested to provide a quote for the costs involved in a potential 100 production standard P.1127 aircraft.
Meanwhile, Hawker believed that the continuing development of the P.1127 would serve a successful demonstration, acting to dissuade potential customers from pursuing competing 'paper' VTOL aircraft projects.

On 2 November 1960, the Ministry of Supply issued a contract for a further four prototypes to be produced, which were intended to develop the aircraft further towards being a realistic combat design, such as the refinement of the wing, engine improvements, and of accompanying operational equipment.
Throughout this period, improved models of the Pegasus engine were rapidly developed, such as the Pegasus 3 being capable of 15,000 lbf (67 kN) of thrust.
Apart from the improved powerplants, the first four P.1127 prototypes were quite similar; the fif
On 15 July 1960, the first "P.1127 Prototype V/STOL Strike Aircraft", serial XP831, was delivered to Dunsfold Aerodrome, Surrey, to commence static engine testing. On 31 August 1960, the Pegasus engine was run for the first time while inside the airframe. Some of the tests were performed from a purpose-built platform at the aerodrome which functioned to deflect the hot exhaust gases away from the aircraft during early hovering trials while more powerful versions of the engine were developed. On 13 October 1960, the first Pegasus flight engine, capable of generating 11,300 lb of thrust, was delivered to Dunsfold.
On 21 October 1960, the initial tethered flight, performed by XP831, was conducted at Dunsfold; at this stage of development, this feat had required the airframe to have been stripped of all extraneous weight and restrictions on the engine meant it could not be run at full power for more than 2.5 minutes at a time. Several tethered flights took place, partially so that the test pilots could familiarise themselves with the hovering controls; on 4 November, the first tethered flight without use of the auto-stabiliser system was accomplished. In mid-November, conventional taxying trials were performed at speeds of up to 70 knots.
On 19 November 1960, the first un-tethered free-flight hover of XP831 was achieved; a week later, the first publicity photos of the P.1127 were released. Prior to the first flight, Hooker is claimed to have asked of Camm "I suppose you are going to do some conventional flying first Sydney?" and Camm replied "What for?"  Hooker said "Well you know, just to make sure the aeroplane is a nice aeroplane, and everything under control."  Camm replied, "Oh, Hawker aeroplanes are always beautiful, nothing wrong with a Hawker aeroplane, not going to bother with that. Vertical first time".
On 13 February 1961, XP831 performed its first conventional flight, flown by Bill Bedford and lasting for 22 minutes. Soon after this, XP831 was refitted with a new model of the Pegasus engine, capable of generating 12,000 lb of thrust, prior to embarking on new hovering trials in May 1961. In June, XP831 attained another milestone in the program when it performed the first transition from vertical hover to horizontal flight, initially flying the length of Dunsfold's runway at a height of 50 meters.
On 7 July 1961, the second prototype, XP836, performed its first take off conventionally. Continuing tests of the two prototypes proceeded to close the gap between vertical take off and flight, a feat which was achieved on 8 September 1961. During September, the feat was repeated multiple times by both prototypes, transitioning from vertical to horizontal flight and vice versa, including instances in which the auto-stabiliser was intentionally disabled.
During the flight test program, the issuing of NATO Basic Military Requirement 3 (NBMR-3) did not prove to be the opportunity as envisioned by Hawker, as NBMR-3 sought performance characteristics of which the P.1127 was not only unable to meet, but unlikely to be developed to meet in its current form either. As such, in 1961, there was little military interest in the P.1127 program, although, in January 1961, Hawker was requested to provide a quote for the costs involved in a potential 100 production standard P.1127 aircraft. Meanwhile, Hawker believed that the continuing development of the P.1127 would serve a successful demonstration, acting to dissuade potential customers from pursuing competing 'paper' VTOL aircraft projects.
On 2 November 1960, the Ministry of Supply issued a contract for a further four prototypes to be produced, which were intended to develop the aircraft further towards being a realistic combat design, such as the refinement of the wing, engine improvements, and of accompanying operational equipment. Throughout this period, improved models of the Pegasus engine were rapidly developed, such as the Pegasus 3 being capable of 15,000 lbf (67 kN) of thrust. Apart from the improved powerplants, the first four P.1127 prototypes were quite similar; the fif
Hawker Siddeley P.1127