For someone trying to calculate an appropriate "best range" speed, this article is a bit confusing.
It mentions minimum drag speed, which makes a lot of sense. But then compares this to clean stall speed. To my understanding, min drag speed is Vglide, which has no apparent correlation to clean stall (Vs1). For example, with a C172N, Vs1 is 47; but for a C172P, Vs1 is 44. Both have a Vglide of 65, which is far more than one third over Vs1 as the article suggests as min drag speed. The same goes for a C152 -- Vs1 is 40, and Vglide is 60, far more than one third over Vs1.
It then goes on to state that the minimum drag speed (Vglide) is NOT the best range speed. This also makes sense, but the article then states that the best range speed is approximately 1.5 times clean stall speed (Vs1). For the above-mentioned C152, this is Vs1 (40) times 1.5 = 60, which IS Vglide. For a 172N, 44 * 1.5 = 66, which is one knot over VGlide; and for a C172M, 47 * 1.5 = 70.5, which is 5.5 knots over Vglide.
So, for two of these planes, calculating the "best range" speed as 1.5 times "clean stall" (Vs1) it gives a result that matches Vglide (minimum drag speed), which the article says is NOT the best range speed.
So what is the correct starting point? Minimum drag or clean stall?