DAEWOO HEAVY Industries (DHI) of South Korea is making further changes to the design of its KTX-1 turboprop basic trainer, to improve manoeuvrability and stability.
A fourth prototype, scheduled to have its maiden flight in May, will incorporate structural and aerodynamic modifications. The aircraft is the final flying prototype planned for the programme and had originally been due to fly towards the end of 1995.
The major change centres on the position of the KTX-1's horizontal stabiliser, which has been moved back by 300mm and lowered by about 150mm. The aircraft's vertical stabiliser remains unchanged.
The KTX-1 design's original 10.1m wing span, has been widened by an additional 300mm, further enlarging its 15.5m2 wing area. At the same time, the wing's aerofoil has been remodelled, to produce a sharper contour.
Other refinements include a shortening of the trainer's nose length by 200mm. DHI had originally lengthened the forward fuselage of the third prototype by 300mm, to accommodate the more powerful 710kW (950shp) Pratt & Whitney PT6A-62 turboprop.
DHI and the Korean Government's Agency for Defence Development (ADD) decided to modify the design, based on the performance of a third prototype first flown in August 1995.
It has since been returned to DHI's Changwon plant, to be modified to the same standard as that of the fourth prototype.
The latest changes are the second major revision to the KTX-1 design since the first PT6A-25-powered prototype was flown in 1991. It was decided, to switch to a larger engine and four-blade Hartzell propeller, after the first two aircraft were found to be under-powered.
In the meantime, DHI and ADD flight-development testing continues at Sachon AB, with the second prototype. The lead aircraft was lost in 1995, after the pilot accidentally ejected. The first production trainer is targeted for entry in service in 2000.
Source: Flight International
