the Jet Provost to be satisfactory, refinements were made, such as shortening the legs of the landing gear for a smoother ride when deployed at semi-prepared airstrips. On 19 February 1955, the first of ten pre-production aircraft, designated as the Jet Provost T1, performed its first flight. In May 1955, three of the pre-production aircraft were assigned for the first stage of service trials with the Central Flying School (CFS) of the RAF to determine the value of the Jet Provost in the ab initio training role and to develop a syllabus for the training program. During the second stage of CFS trials using the same three aircraft, actual students were introduced to the type for practical evaluation purposes, which was performed at RAF Hullavington until the successful completion of trials on 2 July 1956. According to feedback from CFS examiners, the Jet Provost had noticeably improved the performance of students during its trial deployment. Further development As a result of the results and responses produced from the trials performed using the pre-production aircraft, Hunting Percival proceeded to develop and incorporate several different improvements upon the design. Amongst the changes made was an overall smoothening of the fuselage lines, hydraulic systems being substituted for pneumatic counterparts, and the addition of a dorsal fillet; the new model was designated as the Jet Provost T2. On 1 September 1955, the first Jet Provost T2 made its first flight. This variant was used only for development work; in addition to seeing use at Hullavington, three Jet Provost T2s were dispatched overseas for winterization trials in Scandinavia and a series of sales tours across Europe, Canada, the United States of America, and Latin America. In June 1957, a production order was placed for the first 40 of the developed Jet Provost T3, featuring a more powerful Armstrong Siddeley Viper jet engine, ejector seats, a redesign of the airframe, and a shortened and strengthened version of the retractable tricycle undercarriage. Percival built a single example, which was used purely for structural tests throughout the development stages, giving the designers valuable research into what could be achieved with the basic design. On 22 June 1958, the first Jet Provost T.3 conducted its first flight. In total, 201 T3s were delivered between 1958 and 1962. The T4 followed in 1960, fitted with a more powerful variant of the Viper engine and first flown on 15 July, and