The crown used to "top" the cap badge which began this thread was known as the "Naval crown" or sometimes the Tudor Naval crown. It featured alternating prows and sterns of wooden sailing ships, and there seem to have been several versions. It was often used on ship's badges I believe (including RN?). There was (very much later) an aviation crown (I seem to recall it MAY have been described as the "Adastral Crown" or something similar), which features birds wings instead of the ship decorations. This is still used for semi-governmental organisations, and I notice it is also used for the badge of the RNZAF Museum (under governorship of a Trust Board), so perhaps also the RAF Museum? Quite hard to find out about these lesser known crowns, particularly if you do not know what they are called. And these days, just to make it even more difficult, they are not "Royal" in any sense. Sovereigns never wore them, so far as I know, and they possibly never even exited as actual objects, being purely symbolic crowns. Any further enlightenment from the more knowledgeable who infest this forum welcomed!