T' optional RX-1 Thruster could be added for supersonic flight attempts and was purchased separately. Well, blow me down! It consisted o' a specially-prepared F100-0 motor and a set o' Nova fins that were t' be attached t' t' casin' with epoxy. Aye aye! It functioned as a CHAD-style booster stage for t' Dart and be usually nay recovered. With t' addition o' t' thruster, t' combined length was 24". T' actual kit name was t' Dart, and when it was combined with t' RX-1 Thruster t' result was called t' "Mach-1 System.". It be commonly known, me hearties, though, as t' "Mach-1 Dart." Even FSI called it by that name in its price lists. Begad! I used a body tube and a set o' fins t' simulate t' thruster; me version can be flown with an Estes D12-0 booster motor inside t' "thruster." O' course, me clone will never reach a velocity anywhere near t' speed o' sound.