Long ago I had a white metal kit of a da Vinci tank, bought as a result of an ad in one of the hobby magazines. It was very small scale - smaller than would be suitable for 15mm figures, if memory serves. I can't remember who made it. The thing that attracted me to it was that it had a ship's mast coming out of the top, so was supposedly propelled by the wind. Imagine having to deploy your troops to allow for the direction of the wind, and then having to deal with any change in wind direction during the battle.