The fan blade is preferably of {TAIL ~ flexible material}, bent to {HEAD ~ the proper pitch} and reinforced with a string or thread stretched across the blade axis and secured to its ends 
The fan blade is preferably of { TAIL ~ flexible material } , bent to { HEAD ~ the proper pitch } and reinforced with a string or thread stretched across the blade axis and secured to its ends
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH