My understanding of the development of RVs is that when the 7,8 & 9 were introduced, the 8 came first, followed by the 9 and then the 7, which was a combination of the 9 fuselage and the 8 wings and empennage. Of course, each plane has its unique parts, but if my developmental timeline is correct, what are the wing and empennage parts common to both the 7 and 8?