Glide speeds PA28R versions
I have been reading up on the procedures for the Piper Arrow (three different variants actually) and something struck me as odd. If you take a Piper Arrow III (PA28R-201) and compare this to a Piper Arrow IV (PA28RT-201T) then there is a marked difference in best glide speeds: 79 kt for the Arrow III and 97 kt for the Arrow IV. These aircraft both have the newer 'tapered' Piper wing and apart from the engine they should be aerodynamically similar (I'm ignoring the changed position of the stabilator here but still). Anyone with thoughts about the 18 knot difference?