The British Carrier Strike Fleet. David Hobbs
rubber deck. NAD made a final proposal in 195212 in an attempt to revive the concept. This suggested designing aircraft with ‘taxiing wheels’ which could be lowered after landing to allow the aircraft to taxi or be moved without needing trollies. The design effort required for such a unique aircraft requirement and the weight and complexity of adding an undercarriage, complete with brakes, on which it could not land, was utterly impractical and was rejected by both the RN and USN and the rubber deck experiment was officially terminated in 1954. In the event, carriers with angled decks, better aircraft design and the rapid evolution of turbo-jet engines solved what had been perceived as the major problem of landing-on high performance aircraft. Although the rubber deck experiments seem bizarre in hindsight, they certainly show the extreme lengths to which the Admiralty was prepared to go in order take its fighters into the supersonic era.
Invention – The Angled Deck, Steam Catapult and Mirror Landing Aid
Jet aircraft with their higher landing speeds needed a longer pull-out once they had taken an arrester wire and space had to be left for both conventional and nylon barriers to protect aircraft parked in Fly 1. By 1951 the amount of parking space left was becoming significantly smaller, limiting the number of aircraft that could be parked after a single land-on and thus the size of the maximum deck-load strike that any given carrier could recover in a single operation. The newer and heavier aircraft in prospect would virtually eliminate the space available for Fly 1 and so, if the RN was not to be forced to return to the clear deck techniques of the 1920s, a solution had to be found. Lateral separation with landing and parking areas alongside each other was not possible on existing ships and would call for unacceptable beam dimensions in new designs. It was a serving naval officer who came up with the simple but elegant solution. Captain D R F Campbell DSC RN was serving as the Deputy Chief Naval Representative at the Ministry of Supply (MoS), in 1951 and he was inspired by some of the concept designs put forward during the rubber deck trials in which the landing area had been offset from the centreline to allow aircraft to be pulled clear once they had landed. Campbell worked with Lewis Boddington to put forward the very practical idea of radial separation. By rotating the axis of the landing deck by a few degrees off the centreline of the ship from a point in the centre of the round-down at the after extremity of the flight deck, several positive and attractive benefits were achieved. Even a slight angle brought the forward edge of the landing area to the edge of the flight deck at a point well aft of the bows, significantly lengthening the space available to bring aircraft to rest after they caught a wire. The area to starboard formed a larger and safer Fly 1 which could be used for parking aircraft after a land-on and the sum of the length of the two areas was greater than the length of the original flight deck. Even better, the angled deck gave pilots a clear deck with no barrier in front of them since aircraft parked in Fly 1 were parked to starboard of the wingtip safety line, clear of the line of flight. If his aircraft’s arrester hook missed all the wires, the pilot simply opened the throttle and climbed away for a further circuit.
The Naval Air Department at the RAE used a model of an Illustrious class carrier in a water tank to demonstrate the advantages of the angled deck, known initially in the RN as the ‘skew deck’ and in the USN as the ‘canted deck’. Model fighters have been used to show the space made available in the offset Fly 1 for parking, an aircraft taking an arrester wire and even one on a stick to show it turning downwind. (Author’s collection)
The concept was demonstrated by photographing a model carrier with an angled deck floating in a tank and by flying trials on Triumph. An angled deck was painted into place with its centreline extending from the starboard quarter to a point on the port deck edge abreast the island, angled 8 degrees to port of the ship’s centreline. In February 1952 examples of all RN aircraft in service and being developed took part in flying trials which involved approaches to Triumph’s angled deck which terminated in low overshoots ordered by the DLCO. No actual ‘touch-and-go’ roller landings were carried out because of concerns that the undercarriage might snag one of the arrester wires, which were still aligned with the axial deck, and might thus cause an accident by snagging a tyre13 but the trials were very successful. No difficulties were experienced flying circuits to the angled deck, the new constant-power approach down a steeper glide slope proved easy and pilot confidence was greatly improved by the lack of a barrier ahead of the landing area. Concerns about potential snags with drift if the wind was not quite down the angled deck and with funnel smoke were found, in practice, to be of no consequence.
The USN was kept fully informed at every stage of the new development,14 quickly appreciated its value and adopted it immediately. Trials similar to those in Triumph were carried out on to a deck painted onto an Essex class carrier in the spring of 1952 and in the summer, another Essex class ship, the USS Antietam (CV-36), was fitted with a full 10-degree angled deck and the arrester wires realigned to line up across the new landing area. The first-ever arrested landing on an angled deck was carried out by her captain, Captain S G Mitchell USN, flying a North American SNJ Harvard on 12 January 1953 and a series of trials with a variety of aircraft types followed. These included a visit to Portsmouth in the autumn and RN trials which included a large number of arrested landings by operational RN aircraft. DLCOs were embarked to give height corrections for aircraft on finals and the cut for piston-engined aircraft. Known initially as the ‘skew deck’ in the RN and the ‘canted deck’ in the USN, the simpler term ‘angled deck’ was soon adopted by both and the concept was adopted immediately. The only delay was caused by the significant amount of dockyard work needed to build the port-side sponson that supported the forward end of the new landing area and to re-align the arrester wires. Since its invention all carriers built or modified to operate fixed-wing aircraft in every navy have been fitted with angled decks.
The second important invention of this period was also the work of a man with wartime naval experience. Commander C C Mitchell RNVR had proposed the development of a slotted-cylinder catapult to the Admiralty in the 1930s but, with the minimal requirement to catapult the light naval aircraft of the time, the existing hydraulic catapults had been deemed adequate and the idea, although recognised as sound, was not progressed. With the greatly increased weight of naval aircraft in 1945 and the prospect of even heavier jet aircraft in the near future, however, the BH 5 hydraulic catapults to be fitted in Eagle and the 1943 light fleet carriers were recognised as being at the end of their development potential15 and Mitchell resumed work on his more powerful catapult. He was able to hasten development when he found that the Germans had used a similar catapult to launch V-1 ‘flying-bombs’ and he acquired components through the British Intelligence Operational Survey Team. The result was a prototype catapult in which rams were driven along parallel cylinders by steam pressure. A cradle linked the rams so that they ran along their cylinders together and provided the structure on which the towing shuttle was fixed. This ran along a slot at flight deck level, pulling the aircraft forward by means of a wire strop which was looped at either end onto hooks on the underside of aircraft.16 Rubber seals ran along the tops of the cylinders which were forced open by devices on the leading edges of the cradle and resealed behind it to allow its passage without significant loss of steam pressure.17 High pressure steam was provided from the ship’s boilers and stored in large accumulators at up to 4000 psi.
The hydraulic catapult had used a short piston which activated miles of wire-rope reeving in pulleys which translated the piston stroke into movement of the shuttle. Maximum acceleration was reached after less than a third of the shuttle’s travel and the wire pulleys were a constant source of unserviceability. The new slotted-cylinder, or steam, catapult, on the other hand, not only had a greater energy potential but accelerated more smoothly to reach a maximum at two-thirds of the shuttle’s travel. The Admiralty immediately saw the potential of the design and awarded a development contract to the Scottish engineering firm of Brown Brothers and Co which Mitchell joined when he was demobilised from the RNVR. After extensive trials with a development catapult ashore, the prototype steam catapult, BXS1, was built into a new structure on the deck of the maintenance and repair carrier Perseus in Rosyth Dockyard during 1951. Sea trials were carried out first with wheeled trollies known as dead loads which could be accurately weighed,