Did all of Leonardo da Vinci's inventions work?

Leonardo was a multi-faceted genius. It does his reputation no harm to say that very few of his inventions were actually tried by him or even by other men of the time. Sadly, many of his inventions could not have worked using the materials and techniques available then. Some of these could have worked using modern materials; and some had fundamental flaws.

The battle tank was a good idea, but required an engine; a steam engine might have worked, but muscle power just couldn't do it. To make a modern tank requires an internal combustion engine and high-tensile steel for armour.

The helicopter was a nice idea but flawed in detail. An engine is a must, and high strength, lightweight materials.The type of rotating wing drawn by Leonardo is fundamentally flawed - it just won't do the job even with todays materials.

The flapping-wing flying machine drawn by Leonardo has the strange distinction of being theoretically impossible and at the same time already achieved ! Working models of this invention were on sale in the street market in Montmartre (Paris) more than 25 years ago. But, a model is only a model; the drawing shows an ornithopter carrying a man and powered only by a man's muscles. That simply can't be done. Man powered flight has been achieved, just, but only with a fixed wing and a large propeller.