I come back to this years later having just read "The Wright Brothers" by David McCullogh. And it struck me as notable that this story first appeared about a year after the Wright Brothers began flying their airplane, whose construction of two fabric-covered, wood framework wings rather resembled kite technology. I think a pair of kites powered by rockets is a very 1909 kind of idea.

Having read the "Gunpowder Epic" volume of Needham's "Science and Civilization in China, I think that a Wan Hu would have made a model dragon or bird if he were real, or even a truly Chinese legend.