Page 29 - Theory and Design of Air Cushion Craft

14 Introduction to hovercraft

Table 1.4 Early Hovercraft accidents causing overturning and major skirt damage
Item Model Country Date Damage Data source
1 XR-1 USA Dec. 1964 Transverse overturning in waves ACV 1965
Vol. 6 No 34
2 SR.N5-004 UK Apr. 1965 Overturn in calm water due to ACV 1965
plough-in at yaw angle (in Norway) Vol. 6 No 34
3 SR.N6-012 UK Mar. 1972 Overturn, flooding, in very Hovercraft &
choppy seas on the Solent, 5 Hydrofoil 1972
passengers died of drowning No 1
4 SR.N5-007 UK May 1965 Overturn in calm water due to ACV 1965
plough-in at yaw angle (in San Vol. 6 No 35
Francisco, USA)
5 SR.N5-005 UK July 1965 Overturn in calm water due to ACV 1965
plough-in at yaw angle (in UK Vol. 6 No 39
waters)
6 SR.N4-001 UK Sept. 1968 Skirt damage from waves, Lloyds List
subsequently hull structure 1968, 47951
damage, while in service
7 SR.N4-003 UK July 1971 Skirt damaged and hull damage Hovercraft &
while in service Hydrofoil 1971
No 7
8 SK5-015 UK Nov. 1971 Severe damage to hull structure ACV 1976
from waves, craft sank Vol. 11 No 7
9 N.500 France May 1977 Craft caught fire while in Hovercraft &
workshop, almost completely Hydrofoil Vol.
destroyed 16 No 7

stretched to the Mark III version, at 208 tons, so that 400 seated passengers and 55
cars and coaches could be accommodated. In itself, the SR.N4 is more than just
another hovercraft, rather, it even now symbolises the hopes and aspirations of the
entire industry, particularly those elements pursuing the development of the amphibi-
ous skirted hovercraft. The basic concept, modified to include the technological devel-
opments in gas turbine engines, skirts and structures is still capable of extension to
around 750 tonnes, with the tremendous work capacity that this represents.
At B.H.C., [207] the follow up to SR.N4, designated the BH.7, was built first as a
trials craft for the British Royal Navy, and later as a patrol craft for Iran. Smaller than
the SR.N4 and grossing 45 tons it makes extensive use of components developed for
SR.N4. While the trials showed that the BH.7 was a useful coastal patrol craft, its
operation was too different to the units in many navies already operating traditional
high speed patrol boats, so the expected market did not arise. The British military ser-
vices formed a joint trials unit to test and develop ACV technology in September
1961, located at a Naval Air Station (HMS Ariel, Later HMS Daedalus) in Gosport.
The unit was in operation until December 31st 1974, and during this period tested
most of the major marques developed in the UK. [213] A flypast of SR.N6, BH.7,
and Vosper Thornycroft VT.2 is shown in Fig. 1.13. Hovermarine Limited was
founded in the UK in 1965 in order to undertake the research and development of
sidewall hovercraft which offered the possibility to save lift power and be more attrac-
tive to the traditional ferry operators. The first of this kind of craft, HM-2, was
launched in 1968 (Figs 1.14 to 1.17). This was developed with a modified skirt system
to become HM-2 MK2, and lengthened from 16m to 18m to become HM-2 MK3
over a relatively short period, and later to 21m, to become the HM-221 (Fig. 1.18).