How glider enthusiast may help save Russian sub

The LR5 is lowered into the sea

By Paul Sussman, CNN.com writer

The LR5, one of the world's most advanced underwater rescue craft, owes its existence to one Briton's passion for fixed-wing gliding.

The man in question was Sir Leonard Redshaw, former chairman of Vickers Shipbuilding and Engineering Ltd., from whose initials the LR5 derives its title.

Redshaw, who was born in 1911 and spent his entire career in the shipbuilding industry, was a lifelong gliding enthusiast. In the late 1960s this enthusiasm brought him into contact with a York-based glider-making company called Slingsby Ltd.

At the time Slingsby was experimenting with a new substance called Glass Reinforced Polyester (GRP). This was an ideal material for constructing gliders because as well as being extremely strong it was also light and good at retaining heat.

Redshaw, however, with his experience in the shipbuilding industry, immediately recognised another potential application for the new substance: as the casing for submersibles.

Until then manned deep-sea submersibles had been made of steel. Redshaw's idea was to use GRP instead.

Contact was made with a Florida-based company called Perry Triteck who produced an underwater craft known as the L1. After hearing of Redshaw's theories they granted Slingsby a licence to create a version of the L1 in the UK, out of GRP. The LR series was born.

The first LR craft, the LR2, appeared in 1974. Although it had a GRP casing it was in other ways unrecognisable from the submersible involved in the Kursk rescue operation.

It was smaller, less technologically sophisticated and, most significantly, not intended for underwater rescue (it had no rescue chamber). Rather, it was designed to inspect sub-sea structures in the North Sea oil and gas fields.

The LR2 was succeeded by improved versions and, in 1978, an LR5. The LR4 and LR5 did have a chamber capable of transferring personnel from the outside, although once again it was not designed for rescue purposes, but rather to eject deep-sea divers.

It was only in 1983, when the LR5 was purchased by the Ministry of Defence, that it was adapted for submarine rescue. Since then it has undergone a series of alterations and upgrades, which have enabled the craft to carry more people (the original rescue chamber could only fit three; the current one carries 16).

Based at the Royal Navy's Submarine Rescue Headquarters (SRH) in Renfrew, Scotland, the £8 million submersible is the only one of its kind in the world. Ten metres long by three metres wide and weighing 21 tonnes, it is capable of operating up to a depth of 1,500 feet (457 metres).

Its two-man crew is housed in its forward section, with a rescue chamber located in the centre of the craft and a battery-driven propulsion system at the rear. Batteries last for up to eight hours before needing to be recharged at the surface.

The LR5 latches onto the stricken submarine by means of a watertight "transfer skirt" which attaches around the mouth of the vessel's emergency escape hatch, allowing up to 16 crewmen at a time to pass into the submersible and be taken to the surface.

A special "wedge" allows the skirt to be tilted so it can still lock-on to the submarine even if it is lying at an angle.

In 1997 an LR5K rescue craft was built for South Korea.

Perry Triteck was subsequently bought by the French company Coflexip Stena Offshore, who in May 2000 also bought Slingsby, merging the two companies to form Perry Slingsby Systems Ltd.

Sir Leonard Redshaw died in the early 1980s.

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