The Harmon Rocket I was a modified single place Van's RV-3 sport plane while the Harmon Rocket II is a modified Van's two place RV-4. Autos have been modified for decades by people seeking to make a vehicle meet their needs and desires and the Harmon Rocket is no different. When you purchase a modification kit to build a Rocket from John Harmon the kit is an extension of the RV-4 kit which is purchased from Van's. Please review the PARTS/MATERIAL page for details of what to order. Harmon Rocket II is beyond total performance. John Harmon’s conversion kit for the RV-4 is the ultimate aviation experience for recreation and sport flying. From winning awards at Oshkosh to EAA fly-ins and air shows this aircraft should be the choice for RV builders of kit plane plans or individuals interested in avionics for homebuilt aircraft. The HRII is not a quickbuild kit as many builders of the Rocket prefer to be more involved in the aircraft building process and express a preference of some minor fitting and trimming. If you are looking for a home built experimental aircraft consider the flexibility and performance of the Harmon Rocket.