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Hovercraft development  - composite / sandwich constructions
252 Industrial Drive #4
78578 - Port Isabel - TX
Tel.: (956) - 9435150


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Manufacturer: Saunders Roe
Built: Circa 1956
Size: 1 / 6th scale
Approx. 6 ft x 4 ft
Constructed from balsa wood and thin plywood

Powered by a single internal combustion engine driving a large central fan to
provide a continuous flow of air to a peripheral jet. A small IC engine was
mounted at the rear of the model to provide thrust.


This is the last surviving original model from the development model test
program that was undertaken prior to the construction of SR.N1, the world's
first, practical, man carrying hovercraft. Model trials were still going on alongside
the production of the real craft.

The model represents the early stage of development of the SR.N1 before it was
fitted with any skirts and this was how the SR.N1 was first flown on the Solent in
1959. The craft flew in calm conditions but the air loss was great and the
man carrying craft was soon fitted with a simple skirt to help to contain the air
and enable it to work better over waves.

Dimensions & Performance

Length: 30 feet
Width: 15 feet
Weight: 5 tons
Hover height: 2 feet

Maximum speed: 45 knots
Endurance: 2 hours

Power / Lift: 3 x 150 H.P. Rover 2S/150 gas turbines (1 for lift, 2 for propulsion)

Payload: driver, co-driver + 6 observers

Designed as a one third scale model of a concept design for a side-loading
passenger and car ferry and used in a number of experiments.

Wrap-around loop-segment skirt

This was the first hovercraft to use this type of skirt, which had been derived from
earlier tests, and has segments the full depth of the cushion. The skirt surrounds
the air cushion which is a single-cell plenum chamber without the
compartmentation used on earlier craft to give stability in roll and pitch. On HD.2
the peripheral stability is obtained from changes in the cushion area due to
deformation of the angled segments of the skirt, as the craft rotates relative to the
surface over which it is traveling.

This type of skirt has the great advantage of being easily accessible from outside
the craft, even when off-cushion. Individual segments can be detached and
replaced in minutes and a complete new skirt can be fitted within two hours. The
skirt material weighs about 1 lb per square yard and is a synthetic weave coated
with artificial rubber. In order to reduce the effect of abrasion, delimitation and
tearing, which frequently occur in a marine environment, segments of a different
material are fitted at convenient points on the periphery.

This type of skirt revolutionized hovercraft production from large commercial or
military craft down to single seat racers.


Dimensions & Performance

Length: 77 ft
Width: 45 ft 6 ins
Weight: 48 tons
Height on landing pads: 33 ft

Hover height: 5 ft 6 ins
Bow door: 13 ft 9 ins x 7 ft 10 ins
Headroom at centerline: 7 ft 10 ins
Integrated Lift and propulsion: Rolls Royce / BS Marine Proteus 15M / 541 gas
turbine 4,250 shp at 15ºc
Generators powered by 2 Rover IS90 gas turbine APUs
Accommodation: Cabin crew of 3, payload up to 14 tons
The model could accommodate up to 152 fully equipped troops or combination of
troops, vehicles, equipment and stores but this particular BH.7 contained
provision for the crew to live on board for several days
Special Equipment: Fitted with MCM Sonar
Fully amphibious
Maximum speed: 65 knots
Endurance: 11 hours

(See main BH.7 Page for further technical details and pictures of the craft in


The BH.7 was designed as a rugged, reliable, high-performance military vehicle. It
was used extensively as a trials evaluation craft prior to entering into service with
the Inter service Hovercraft Unit on 28th September 1970. In early 1972 the craft
was subjected to an intensive cold weather trials program in Sweden during
the course of which it achieved speeds of over 70 knots over ice in the Gulf of
Bothnia. During this trip the BH.7 covered 1,000 miles which was the longest
journey undertaken by a hovercraft at that time.

The BH.7 was subsequently fitted with a redesigned bow incorporating an
hydraulically operated clamshell bow door and ramp to allow the loading of
vehicles on to the main deck.

Although a high speed craft the BH.7 was also a good sea keeper with a
comfortable ride. It's inherent amphibious qualities gave it extreme freedom of
operation as it was not dependent on ports, harbors or deep water. It could be
deployed and camouflaged on any suitable beach and with a reaction time of 2
minutes it was superior to anything of it's day. It could operate over any terrain
and deliver troops 'dry' onto many beaches otherwise considered inaccessible.
The high speed, lack of surface penetration, low magnetic and underwater
acoustic signature made it almost immune from damage by torpedoes, mines or
other underwater weapons, rendering it an ideal mine countermeasures vessel.
All these uses were developed using the prototype craft which now belongs to
the Museum. The BH.7 was also used as a fishery protection vessel and it was
used for a time patrolling the one way system in the English Channel.

In 1978 it was used as a mine counter measure vessel, both for sweeping and
detection and during this incarnation it was fitted with MCM Sonar, Plessey type
193. The prominent 'chimney' on the BH.7 Mk 2 houses the sonar head which can
be lowered for detection and raised for rapid transit. The craft last flew in October

There were a further six BH.7s produced, all of which went in to service with the
Imperial Iranian Navy, where, although they operated in high ambient
temperatures, they achieved block speeds in excess of 50 knots and maximum
speeds approaching 70 knots, thus demonstrating the extreme versatility of this
craft. The Iranian craft were used very effectively in the amphibious assault role
and have even acted as helicopter refueling craft. Two of these craft were
externally identical to the prototype, though being designated as Mk 4 and the
other four, Mk 5s, had a narrower superstructure and flat side decks for housing
the missile launchers. Following the overthrow of the Shah of Iran there was a
trade embargo which prohibited further sales to Iran and effectively halted the
production of this craft.

Special Features

1. Used many of the proven systems developed on the SR.N4.
2. Built for the British Government as an experimental naval patrol craft.
3. Capable of operating in wave heights up to 9 ft significant (15 ft maximum) and
wind speeds of over 30 knots.
4. Used for the evaluation of a highly sophisticated navigation system.
5. Used the first 21 ft diameter glass fiber propeller.


The ex-British Army 200 Hovercraft Squadron RCT CC.7 XX101 originally based in
Gosport was acquired by the Hovercraft Museum Trust in 1992. The craft was
previously last seen in Gosport in 1984 at the HMS Daedalus Air Day before
MARTSU transported her to the Rotor craft Museum at Weston Super Mare, after
several years in the Fleet Air Arm Museum at Yeovilton. On 1st February 1992 the
CC.7 was loaded and carried to Rye, East Sussex where a year long restoration
project was undertaken under the leadership of Peter Cahill and three
engineering friends.


Following commercial trials with earlier craft which were still owned by the
manufacturer, this was the first hovercraft built and sold to provide a commercial

The build numbers of SR.N5 and SR.N6 were in consecutive order of construction
from 001 to 068 irrespective of type. 009 was the first SR.N6 built (See the
Hovercraft Production List page for details).

009 was built in 1965 as an SR.N6 Mk 1. It is the same width as an SR.N5 and it is
basically a stretched version of that model, providing over double the seating
capacity. The SR.N2 and SR.N5s operated commercial services as trials craft, but
this was the first production craft to enter commercial service. After initial trials it
was operated by Scandinavian Hovercraft Promotions of Oslo, trading under the
name of 'Scanhover'. It entered service in June 1965 and it was joined by 011
operating on a 120 mile route, with six stopping points, in the Aalesund area. It
later operated between Aarhus and Kalundborg in Denmark and in February and
March 1966 the craft also successfully underwent cold weather trials in Sweden,
in the Gulf of Bothnia.

In the spring of 1966 both craft were acquired by British Rail Hovercraft Limited,
then trading as 'Seaspeed' and the Southampton to Cowes passenger service
commenced on 1st July 1966. These craft were also used on the Portsmouth
Harbour Railway Station to Ryde route between 1967 and 1969, in addition to
operating the Southampton to Cowes route. In 1972 the craft were taken out of
service in order to be stretched by a further 10 feet and they were then
designated SR.N6 Mk 1S. 009 went back in to service on the Cowes route on 19th
March 1972 and continued in service with Seaspeed until 2nd May 1976 when it
was taken over by Hovertravel, of Ryde, who continued the Cowes route service
until 24th December 1980.

The Seaspeed Cowes to Southampton service, whilst operating in its own right,
had the primary purpose of evaluation, training and preparation for the launch of
Seaspeed SR.N4 cross Channel services in 1968.

009 was refurbished by BHC as an apprentice exercise before being donated to
Southampton Museums. It was originally intended to display it at the Hall of
Aviation in Southampton, but due to lack of space, the Hovercraft Museum has
been loaned the craft on a long term basis.

Special Features

1) By increasing the length to accommodate 38 passengers instead of the 18
carried by the SR.N5, and subsequently extending it to accommodate a further 20
passengers, the SR.N6 made commercial operation a much more viable

2) In increasing the length of the craft BHC demonstrated the efficiencies
achieved through increased size and continuous development of skirt

    Although double the weight and with three times the payload, the engine was
    only increased by 100shp from 900shp to 1,000shp.

    The hover height was very little reduced from that of the SR.N5.

    The width remained the same so the increased area of the cushion was not
    increased by the same proportion as the length.

    The air loss is proportional to the periphery of the skirt, whereas the lift is
    proportional to the area of the cushion so, by increasing the periphery
    slightly, the supported area could be increased by a greater amount.

    Since the craft is hovering on water, the drag incurred by a larger craft is
    very little more than a smaller one and the propulsion required for the same
    performance is only slightly more.

3) By Increasing the capacity to 58 seats in the Mk 1S an important matching to a
typical coach load of people was achieved.

4) The SR.N6 provided the role model for many larger craft built around the world.


Data with permission from
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