I thoroughly enjoyed reading the article “Fixing Your Float” in the September 2020 issue. As you accurately point out, the “desired airspeed” over the numbers is not always in keeping with the numbers published by the airplane manufacturers. As is mentioned, the optimal approach airspeed varies with airplane design and weight. Yet another variable affecting stall speed is center of gravity (CG). Aft CG results in a lower stall speed due to less wing loading.
Forward CG results in a higher stall speed due to increased wing loading. Reading on in your informative article, I expected to come across some mention of the utility of angle of attack (AoA) indicators. As a private pilot who flies a Cardinal RG, most of the time at well below gross weight, the published approach speeds are often higher than optimal. In my first few years of Cardinal ownership, I commonly found myself floating down the runway until making the airspeed adjustments, as you mention in your article.
