Handley Page HP.115 - Design and Development

Design and Development

The HP.115 was designed to explore the low speed handling characteristics and aerodynamics of slender, delta wing aircraft. It was originally intended to be a glider, being towed by a Canberra aircraft to high altitude of around 30,000 ft (9,140 m). After reviewing costs, it was estimated that a powered version would achieve 200% more flying time at 95% less cost per hour.

Originally intended to be an all-wood glider, design calculations were carried out at Slingsby Sailplanes as the Slingsby T.48, but when the requirement changed to a powered aircraft work was transferred to Handley Page as the HP.115. The HP.115 featured a delta wing of very low aspect ratio swept at 75° and a fixed tricycle undercarriage derived from the main gear of a Percival Prentice and the nose-gear from a Miles Aerovan. The fuselage was a shallow rectangular section girder, with a nacelle at the nose to house the cockpit. It was powered by a single Bristol Siddeley Viper turbojet set over the wing at the base of the tailplane fin. The fin had a bullet fairing at the top to accommodate a cine-camera to record airflow visualisation experiments, some of which employed smoke generators mounted on the wing leading edges.

The aerofoil section was a modified bi-convex type with the maximum thickness at 40% of the chord. This section was chosen as being representative of the type likely to be adopted for a supersonic transport. It had a favourable chord-wise distribution of cross-sectional area and hence a low wave drag in supersonic flight. A unique plywood leading edge was employed wherein new sections of different degrees of camber could be substituted although in practice, this feature was never used.