Expert: Paul Soderman - 12/24/2008

Question
QUESTION: an afterthought...once in his diary, Hooke describes his flying machine as a vane. while this might be (and has been) interpreted as "wing", isn't it possible Hooke was thinking of vane as in "weathervane"? blades spinning on an axle? if so, could the gunpowder engine have powered a helicopter-type machine?  we also know that he did produce a small working model of the machine. does small size influence the realm of possibilities - like the single stroke piston you described last question?

ANSWER: Sorry Judy, that's quite a stretch from the word vane. Hard to tell what Hooke was thinking.  Yes, size matters but a small working model is a good way to demonstrate a technology. Big or small, the power-to-weight ratio is probably similar unless you get super big or super small.

---------- FOLLOW-UP ----------

QUESTION: Paul, after writing this I found a description of Hooke's notes and it certainly sounds like one of his plans was indeed a "weather vane" type contraption in addition to the wings, but perhaps it is just that I cannot envision another way to interpret his words. Can you?  "by means of Horizontal Vanes plac’d a little aslope to the Wind, which being blown round, turn’d an endless Screw in the Center, which help’d to move the Wings, to be manag’s by the Person by this means rais’d aloft"

Answer
Yes, it sounds like he is describing a man-powered or man-controlled helicopter.  The vanes are rotor blades set at angle of attack.  Didn't Da Vinci design the same thing.  I can see why Hooke wanted to use gunpowder.  A man-powered helicopter is probably impossible.  The power required to lift you and the machine off the ground in a sustained fasion is excessive. Machine or man power, a control system is a necessity.  Plus you need to counter the torque or you will spin like a top.  That's why helicopters have tails.  Hooke was dreaming.