BH.7 'WELLINGTON CLASS'

The BH.7 is a 55 ton hovercraft which was designed specifically for naval and military roles. The sole prototype, designated BH.7 Mk 2 (P235) saw service in the Royal Navy starting in 1970 where it was evaluated in a number of different roles including fishery protection, ASW and MCM work.

In 1982 / 83 the RN craft was equipped with an operational mine hunting fit comprising Plessey 193M and 2048 Speedscan sonar equipment and Racal Decca NAV / AIO system. Using this equipment the craft completed a very successful series of trials, operating from the Royal Navy Air Station at Portland. Having completed service with the Royal Navy, this craft was obtained by the trustees of the Hovercraft Museum and it currently resides at Lee on Solent on the South coast of the U.K.

The second and third craft, designated Mk 4, and a further four Mk 5As saw service with the Iranian Navy and are currently thought to be in storage after trade embargoes effectively ceased their operation.

LIFT AND PROPULSION

Power for the integrated lift and propulsion system on the Mk 2 and Mk 4 is provided by a Rolls Royce Marine Proteus 15M/541 gas turbine with a maximum rating at 23 ºC of 4,250shp. On the Mk 5A, a 15M/549 is installed with a maximum rating of 4,250shp. In both types the engine drives, via a light alloy driveshaft and bevel drive gearbox, a BHC 12 blade centrifugal 3.5m diameter lift fan and a British Aerospace Dynamics four blade variable pitch pylon mounted propeller. Propeller diameter on the Mk 4 is 5.79 m and 6.40 m on the Mk 2 and Mk 5A. Normal fuel capacity is up to 13,635 litres.

CONTROLS

Craft direction is controlled by swivelling the propeller pylon angle by a foot pedal. Thrust ports are fitted at each quarter to assist directional control at low speed, and a hydraulically-operated skirt-lift system helps to bank the craft in to turns, thereby reducing drift. Fuel is transferred between forward and aft tanks via a ring main to adjust fore and aft trim.

HULL

Construction is mainly of corrosion resistant light alloy. Extensive use is made of components which were designed for the SR.N4, including the propeller pylon and air intake assembly, basic structure of the control cabin, main cabin sidewalls and windows etc. The bow structure is a Plasticell base covered with glass fibre.

SKIRT

The fan delivers air to the cushion via a continuous peripheral fingered bag skirt made in neoprene-coated nylon fabric. The skirt provides an air cushion depth of 1.68 m. The cushion is divided in to four sections by a full length longitudinal keel and by two transverse keels located slightly forward of amidships.

ACCOMMODATION

The raised control cabin, located slightly forward of amidships on the hull centreline, accommodates a crew of three with the pilot and navigator / radar operator in front and the third crew member behind. The pilot sits on the right, with the throttle and propeller pitch lever on his right, and the pylon angle pedal and skirt-lift column in front. The navigator, on the left, has a Decca radar display (Type 914 on the Mk 5), compass in front and Decometers in an overhead panel.

The large main cabin area permits a variety of operational layouts. In a typical layout the operations room is placed directly beneath the control cabin and contains communication, navigation, search and strike equipment and associated displays. As an alternative arrangement, the main hold floor area of 56 sq.m provides an unobstructed space suitable for loading wheeled vehicles, guns and military stores. Two side cabins equipped with paratroop-style seats, can accommodate up to 60 troops and their equipment. Access at the bow is through a 'clamshell' type door.

The craft has an endurance of up to 11 hours under cruise conditions but this can be extended considerably as it can stay 'on watch' without using the main engine. Provision can be made for the crew to live aboard for several days.

SYSTEMS - ELECTRICAL

Two Rover / Lucas IS/90 APUs provide, via two 55kVA generators, three phase 400Hz ac at 200V for ac and dc supplies.

EXTERNAL DIMENSIONS

Overall Length: 23.90 m
Overall Beam: 13.80 m
Overall Height on landing pads: 10.36 m
Cushion depth: 1.76 m

INTERNAL DIMENSIONS
(Main Cabin)

Cabin Length: 13.20 m
Cabin Width: 4.17 m
Headroom (on centre line): 2.38 m

WEIGHTS

Maximum: 56 tonnes
Disposable Load (including role equipment): 18.3 tonnes

PERFORMANCE
(At maximum operating weight at 15 ºC)

Maximum continuous calm water speed: 58 knots

(Technical information courtesy BHC)

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