Page 50 - Theory and Design of Air Cushion Craft

34 Introduction to hovercraft

a long time, but owing to its poor course/transverse stability and due to the craft dri-
ver at the time applying too much rudder at high speed, it overturned during an emer-
gency turn to avoid collision with a boat. This accident was similar to the casualties
which happened on SR.N5. Fortunately the craft still floated flat with bottom up, and
no one was injured.
Based on the tests of craft 711-1, MARIC completed another test craft version,
71 l-II, with improved manoeuvrability. The adoption of an integrated lift and propul-
sion system greatly improved the handling and manoeuvrability. The craft has now
served as a test craft for MARIC for about 20 years, and so has provided a great deal
of test data (Fig. 1.31). A test sidewall hovercraft, version 711-III weighing 1.7t, was
developed successfully in 1967. The main hull was made in plywood coated with GRP.
With one 190 kW petrol propulsion engine it obtained a maximum speed of 58 km/h
(Fig. 1.32). Various operations of both craft on rapids, shallow water, swamp and
areas not navigable by boats on the Jin-Sah and Lan Chang rivers were carried out in
June-August 1967. From the test results, it was obvious that the SES would be more
suitable for passenger transport on the Jin-Sah River. For this reason, the first Chinese

Fig. 1.31 Prototype ACV model 711-111 in operation.

Fig. 1.32 First Chinese prototype sidewall hovercraft 711-111 in 1967, fitted with bow hydrofoil to improve
seaworthiness.