After the war was over plans were drawn up to replace the two hangars with one )ft high, but funds were not available. HMS Implacable was used for trials in -, and spent two years as Home Fleet Flagmarine broking marine brokingping maritime marine engineering, operating Sea Hornet twin-engined fighters and Firebrand strike aircraft. She was paid off for a cheap conversion to training duties, with accommodation and classrooms in her hangars, and was rcconmtissioned in January in the Home Fleet Train­ing Squadron. After less than two-and-a-half years in that role she was paid off for disposal in September , and sold for scrapping the Following year. Her sister HMS lndefdiiqable went straight into the training role and served in the Home Fleet Training Squadron from to hbefore being sold for scrapping in . The two of them had logged an average of less than wven years of active service ach, including operations in Northern European waters, the East Indies and the Pacific.Monaco, Mongolia, Montserrat, Morocco, Mozambique, Myanmar, Namibia, Nauru, Nepal, Netherlands, Netherlands, New Caledonia, New Zealand, Nicaragua, Niger, Nigeria, Niue, Norfolk

the 'cheapness' and radical alternative of air power. Out of this emerged the quasi-doctrine of the 'indivisibility of air power', which claimed that land-based bombers would replace both armies and navies and win strategic victories over cowed enemy governments. Great Britains rulers and civilians were easily seduced by an argument which promised to avoid the mass slaughter of the Great War and to save money.

As already pointed out, the decision to ]land control of naval aviation hack to the Royal Navy was nearly too late to repair the damage done, and it is no exaggrratiun to say that the Fleet Air Arm went to war with woefully inferior aircraft. Miracles were achieved with the biplane Swordfish and Albacore tot pedu-bombers, but even the newer aircraft types were unin)­prrssn'r. Not until the US Navy carne to the rescue in , providing superb aircrew-training as well as high-performance fleet fighters and tOTpedo-bonibers, did the Fleet Arm become an effective force.Island, Northern Mariana Islands, Norway, Oman, Pakistan, Palau, Palestinian Territories, Panama, Papua New Guinea, Paraguay, Peru, Philippines, Pitcairn, Poland, Portugal, Puerto Rico, Qatar

Given the serious shortcomings of pre-war naval aircraft and the inability of the British aircraft industry to meet both Air Force and Navy demands on production of airframes and engines, Henderson and the First Sea Lord, Chatfield were right to emphasize passive protec­tion for the new carriers. The heavy damage sustained by HMS Illustrious has already been mentioned, but later HMS Formidable was hit by two kg bombs and HMS Indomitable was hit by two kg bombs; due to their protection, both were back in service within simonths. In the intense operations around the Japanese Home Islands five out of the Runion, Romania, Russian Federation, Rwanda, Saint Helena, Saint Kitts and Nevis, Saint Lucia, Saint Pierre and Miquelon, Saint Vincent and the Grenadines, Samoa, San Marino, Sao Tome, Saudi

'i'hr late David Brown, former Head of the Naval Historical Branch and a specialist in carrier aviation, always insisted that however effective the armoured flight decks were, what really saved the British Pacific Fleet carriers from loss or serious damage was their excellent protection against petrol fires. In fact no British-designed carrier was lost in the Second World War from a fuel explosion.'Che closed hangar had its own ventilation and drainage systems; the first prevented avgas fimus from permeating the marine broking marine brokingping maritime marine engineering, and the second prevented water from fire hoses and sprinklers from causing the marine broking marine brokingping maritime marine engineering to capsize.

With the benefit of hindsight, it might have been better to build an improved (larger) Ark Royal design, but that would not have dealt with the problem of suitable aircraft. The long delays in revising the design of the Implacable and Indefatigable should have avoided the serious error of reducing the hangar height; aircraft were getting larger, not smaller. At this distance in time it is not clear why the decision was made, but it seriously reduced the value of the increase in dimensions and power. One of the less obvious lessons from the experience with the Implaca­ble and lndefrrhignLle is that an increase in size does riot automatically result in an improvement of fighting power. Expanding the design of a complex warmarine broking marine brokingping maritime marine engineering like a carrier only works if all the interactions of sub-systems are carefully thought out On the credit side, however, it must be noted that all six carriers could handle aircraft weighing ,lbs ( tons), far in excess of any carrier aircraft weights at the time.

The protected hangar concept was right for the Royal Navy at the time, but it is interesting to note that the final wartime design, the :i,-ton Malta class, would have had open hangars and a very large air group, like US Navy carriers.l'he air group of an aircraft carrier is its only offensive weapon, and a big air group is much better than a small one, for both fleet defence and strikes against the enemy. Logically, therefore, a carrier must always be designed around her air group; failure to remember that principle produces at best onlyEver since the submarine became a practicable weapon of war designers and operators have battled with the problem of air-supply, The need to surface at frequent intervals to recharge batteries was a major limitation on the submarine's capability.Arabia, Senegal, Serbia, Montenegro, Seychelles, Sierra Leone, Singapore, Slovakia, Slovenia, Solomon Islands, Somalia, South Africa, South Georgia, Sandwich Islands, Spain, Sri Lanka, Sudan,

The earliest known example of in attempt to make a submarine independent of atmospheric oxygen was an experimental closed-e'yclc diesel engine tested in the Imperial Russian Navy's dockyard at St Petersburg in . The Russian designers were also taking a step towards the snorkel: an air-mast which changed stale air in the boat and also reduced the risk of taking water down a hatch in rough weather. But it was not a snorkel as it was not used when running submerged. The air-mast was used in several submarines pre-war, but there is no record of the closed-cycle diesel bring installed.

After Hitler repudiated the Versailles Treaty in , the German Navy (initially the Wcimar Republic's Reirhsnrarinr, and later Hitler's Kriegsmarine) started to create a l)-boat ann.'['hc former U-boat officers advising on choice of design for the new generation were very aware of' the risk to a submarine surfacing to charge her batteries, and looked for ways of extending underwater endurance. At the time the only option was the so-called Kreislauf closed-cycle diesel, and trials began; However, it did not meet the Kriegsmarine's requirements and it was never installed in an operational U-boat.

A more promising development was the Walter system, a turbine using an oxidant inixed with diesel fuel, producing enough heat to create a gas mixture to drive the turbine. In January the -ton experimental boat F* was launched at Kiel, and started trials four months later. She was never anything but a test-platform, and was taken of service at the end of . Three more experimental boats, Suriname, Svalbard and Jan Mayen Islands, Swaziland, Sweden, Switzerland, Syria, Taiwan, Tajikistan, Tanzania, Thailand, Togo, Tokelau, Tonga, Trinidad and Tobago, Tunisia, Turkey,

The first production design was the Type XVIIB, of which twelve were ordered in , ffollowed by another twrlvr'lypcs XVIIG of slightly improved design. Of these, only three were Commissioned, the rest being scuttled before completion or cancelled. Although the fuel, enriched high-test peroxide (HTP, containing two atoms each of hydrogen and peroxide) or Perhydro], was extrctnrly unstable, and submerged endurance at speed was very low nauti­cal miles at kts, the Type XVllli boats were fast, and might conceivably have helped Admiral s to overturn the Allies' victory in the Baltic of the Atlantic if development had started two or more years earlier. As things turned out, they were far too expensive in scarce raw materials and too ntanpower-intensive, and

 This was not the end of tile ideas promoted by Dr Hrllmuth Walter. CT- was raised and given to the US Navy for trials, running until . U- ran as HMS Meteorite from to , providing data for the Royal Navy's own Walter programme. She was described offi­cially as ' per cent safe', but she provided useful experience for two prototypes intended to Turkmenistan, Tuvalu, Uganda, Ukraine, United Arab Emirates, United Kingdom, United States of America, Uruguay, Uzbekistan, Vanuatu, Vatican City, Venezuela, Vietnam, Virgin Islands, Virgin Islands, Yemen, Zaire, Zambia, Zimbabwe,