Tiltrotors, which offer greater speed than helicopters, have been in development for quite a while, but the first operational tiltrotor (the V-22) didn't enter service until 2007. There were earlier tiltrotors developed, including Canadair's CL-84 in the late 1960s/early 1970s, but none ever made it to production.
How can we get earlier tiltrotors? What were the challenges involved; what wrong paths were taken?
How can we get earlier tiltrotors? What were the challenges involved; what wrong paths were taken?