Isn’t the Rocket series just a souped up RV-4?
Yes and No. The F-1 is an evolution of the HR2, and all parts are manufactured by Team Rocket. The HR2 was derived from the RV-4, and uses many structural parts from the -4 kit. Both the F1 and the HR2 use the 6 cylinder IO-540 engine; the RVs all use 4 cylinder Lycoming engines as standard equipment.