Perception is the key. According to the chart a scale speed for a 1/7 scale P-51 would be 151 MPH to match up to a full scale P-51's 400 MPH. I know from my many trips to Reno and my involvement in R/C PRO racing that the aprox. 1/7 scale planes used in R/C PRO LOOK ,from the flight line, ABOUT the same size as the full size LOOK from the pit area at Reno. However, the Gold R/C Pro planes SEEM much faster at their 150+ MPH than the full scale LOOK at 400+ MPH. At least to my brain.