Roughly one-half as big as a Boeing 707, both planes have two fanjet engines mounted on the sides of the rear fuselage, cruise at about 550 m.
Instead, in an attempt to recoup its 880 losses, Convair decided to build a long-range jet, the 990, which, by using the then new fanjet engine, would fly faster (635 m.
They are more efficient for subsonic aircraft than the fanjet engines planned for the 1980s; on flights of up to 1,500 miles, the prop fan would be 40% more fuel economical .