"The Black Beret" by Charles Graves (1943), a ficitionalised account of a group of recruits to the RAC early in the war, includes a description of the Rypa and its use. "At last they found themselves in the Rypa - the mock-up fighting-chamber of a tank which has a rolling,yawing, pitching action (hence the word Rypa). The principle was exactly the same as at Winborough and Cowfield (fictional RAC training camps - think Cowfield is meant to be Lulworth), but the panoramas and sand-tables, and the moving targets, were more elaborate. For Bill and Jack it was a pleasant relaxation. There was eye training, which was Whitehill's name for judging distances; there was examination of ground, which involved the pick-up of targets and the search for natural features. Once again, Jack White's experiences in Libya were useful. Just as he had told them during the wireless course that only continual adjustment of the set can make certain of keeping in touch, and that silence on the air is golden, so he advised them in gunnery to conserve their ammunition, wait until they could hit hard, never to forget the possibilities of smoke, fire their Besa when on the move, and their 2-pounder and 6-pounder when halted." A section on wireless training bears out Don J's comments about the code names used; "they ...learnt that "ant" meant anti-tank gun, "Maggie" was synonymous with a machine-gun, that "bandits" were enemy aircraft, and that a "hornet" was an enemy tank" The photo of the Rypa was not quite what I expected though.