Most entries on the invention of helicopter mention a mysterious "1463 European painting" containing a depiction of a flying top. I have no clue what this painting might be, but I do know a remarkable painting ("The Virgin and Child in a Landscape", NG713) showing baby Jesus playing with a cord-spun propeller top dating from the early 16th century. It has been attributed to Jan Provoost (1491-1529). The toy is presumably Chinese in origin (variously attributed to a 320 AD or a 1100 AD invention and claimed to be brought to Europe by Marco Polo). The striking thing about it (that never appeared to me before) is that the propeller is a cross; apparently the toy had devotional value that made it popular at the end of the 15th century.
compare with Memling's http://gallery.euroweb.hu/art/j/juan/virgin_c.jpg
and Massy's http://gallery.euroweb.hu/html/m/massys/quentin/3/index.html
also Provoost's http://www.royalcollection.org.uk/eGallery/object.asp?recent=Y&object=405816&row=18&detail=magnifyhttp://www.casa-in-italia.com/artpx/flem/images/Provost_Metropolitan_Virgin_Child.JPG
...The object held by the Child is a toy that could be made to rise and fall. Its shape recalls the Cross on which the adult Christ will be crucified. http://www.nationalgalleryimages.co.uk/search.aspx?q=Adult&frm=1
...The earliest attempts at helicopter design can be traced back to the days of Leonardo da Vinci in 1486, although some people attribute it to the Chinese Flying Top
designed by Ko Hung around 320 AD. http://www.flying-bike.demon.co.uk/helistuff/heli.htmlhttp://www.suite101.com/article.cfm/general_military/91725
...Since 400BC the Chinese had a bamboo flying top that was used as a children's toy. This toy eventually made its way to Europe and is depicted in a 1463 European painting. Pao Phu Tau (???) was a 4th century book in China that described some of the ideas in a rotary wing aircraft. http://en.wikipedia.org/wiki/Helicopter
...In 1100 AD the Chinese invented a helicopterlike flying top.