Such a nice thing this, it's a 26inch diameter, 20 inch pitch Target Technologies laminated propellor. A rare thing especially as this one doesn't ever seem to have seen service. Before the current vogue for jet powered drones, little prop versions such as the FERRANTI PHOENIX amongst others were use. Indeed, prop drones were used as early as WW2 and there is a famous photo of Marilyn Munro (looking dog rough) fondling a similar sized drone propellor - see pic.
A very nice item and interesting technological collectible indeed.