Power Set AcroMaster & Gemini TUNING. This power set is ideal for flying the AcroMaster as a trainer and classic aerobatic model with a 10" x 5" propeller. In conjunction with an 11" x 5.5" propeller the AcroMaster is transformed into an excellent 3-D aerobatic aircraft. The 10" x 5" propeller is also suitable for use with the Gemini. With this prop the biplane is also capable of 3-D aerobatics.