8 weeks for propellers . home culver props prop speed reduction units big twin engine back yard flyer ultralight about us contact us valley engineering and culver props is a family owned and operated business . the company was established in 1999 but our love for avaiation and innovation came long before . view more ... valley engineering culver props 15685 co. rd. 7100 rolla mo 65401 ph 573 364 6311 ranchair socket.net open monday friday 9 00 5 00 ct tours are available .