A diagram showing the details of the top secret plans for an aircraft carrier, HMS Habbakuk, a giant aircraft carrier made largely of ice and wood-pulp, an idea that was supported by Winston Churchill during the Second World War. The diagram features details of the engineering that would have been involved, such as propulsion units, and insulation. The project was put forward by Geoffrey Pyke in 1942, but was never built as the practicalities involved were too much for the British war effort. The system of construction and propulsion, the crew's accommodation, aircraft hangars and defensive armament are detailed.