From the link above (admittedly a lot of text - however searching the page with the 'Edit' look for word 'capture' will find this text block [the figures are not there so I'll supply an A-4 diagram]:
"Bridle Capture.
For a long time the bridles were regarded as expendable and went overboard after falling away from the machine as it flew away. But more and more intensive flying, the fact that every aircraft type required it’s own special bridle and so placed a demand on storage space on long cruises, as well as the fact that they were becoming more elaborate and expensive, led to a search for a means of saving them. Avoiding damage to the departing aircraft was an obvious requirement, which could occur because of the tendency of the bridle to whip or flail about as it was captured.
It was to be a long time before satisfactory means of doing this were evolved. The author recalls some early attempts, in the late 1940s, by Commander (E) E.C.Beard at the Carrier Equipment Division at R.A.E. Farnborough, to start a systematic study of the mechanics of bridle arrest. An Avenger aircraft was used, but the work was abruptly stopped, it was said because a naval officer was trespassing on R.A.E’s turf.
Van Doorn Unit.
Be that as it may, it was more than ten years after that before the definitive - Van Doorn - unit appeared in service. The system is shown in
Installed on the post WW2 Carriers, HMS’ Eagle and Ark Royal and on most American ships as well, it was in essence a water cooled disc brake connected to a bridle arrest shuttle through a flexible steel driving strap.
The shuttle ran in its own grooves on either side of the main catapult track and was pulled along by lanyards hooked on to the aircraft towing bridle. It then had to be stabilised by three other free running followers, two ahead and one alongside it, also running in it’s grooves.
The lanyards hooking these four travelling elements together were of nylon rope and one pair, located between cleats formed low down near the towing bight of the bridle ran one to each of the forward followers. Another ran directly from the port side towing eye of the bridle to the bridle arresting shuttle. The fourth, rather longer, ran from the starboard towing eye, through a cleat attached to the follower on that side and then across to the arresting shuttle.
When a launch took place, the bridle pulled the shuttle and followers along with it, through the agency of the lanyards. This drew out the steel strap from the drum in the arrest unit. At a predetermined point in the launch run, a low brake pressure began to be applied for the purpose of keeping the strap taught. About 15 feet before the end of the acceleration run the pressure increased to a level dependent upon the launch speed and bridle weight and at that point the shuttle was ready to take the bight of the bridle as the machine flew away.
The rate of bridle arrest was controlled by the brake settings and the lanyards then pulled the bridle downwards, away from the aircraft to ensure a safe departure, assisted by the downturned extension ahead of the catapult. Full brake pressure then came on and the bridle was held in about 40 feet, near the end of the typical beak like projection which are to be seen at the bows of most contemporary carriers.
The bridle was then returned to the starting position by a hydraulic motor rewinding the strap back on to the drum to be ready and in position for the next launch. A deflector plate set into the deck had to be raised to carry it past and over the stationary catapult towing hook during this recovery phase. A separate compartment to contain all this capture mechanism was below deck, alongside the main catapult room, but all the controls for launch and recovery phases were operated from the deck edge howdah.
More recently, US naval aircraft seem to have been designed to take the launch load straight into the nose wheel strut, with just a short mechanical link to the catapult towing hook which hinges away on release and does not need to be captured."
User:Ralph Lewis - Wikipedia, the free encyclopedia