The F-106 Delta Dart was an improved version of The F-102 Delta Dagger, entering service with the Air Force in 1959. The F-106 was originally designated F-102B, but due to structural changes and a larger engine the decision was made to change it to F-106. The two aircraft look very similar, the biggest differences between the two visually is the differently shaped tail fin, the lack of fairings on either side of the jet exhaust in the 102, and the jet intakes on the 106 being behind the cockpit.