Originally Posted by Realslowww
Your a simple simon
,we need to get you enrolled in the physics class as well, the spindle pulleys on the deck make the same degree of rotation in the same time weather it is a 60 or a 72 all things being equal but the longer blade of the 72 covers more distance in that time making it have a faster tip speed. your analogy is flawed, Mr. Spock would find gaping defects in your logic.
.....and we have been over this too. Maybe if everything were exactly the same, same engine and rpm's exactly, same pulley sizes exactly, same deck drive belt exactly etc, the longer blade of the 72" would have the higher BTS. That isn't how it works though in the real world. The longer blade requires more HP to turn due to a couple different reason like blade weight, and generally slightly larger sails. The manu's don't ship them with the same exact deck pulleys and /or PTO pulley. They have to reduce the "gearing" so to speak of the longer blade to keep from loading down the engine below it's correct operating range. Like I have posted to you before, the 72"s usually have lower BTS's. A quick perusal through the manu's site's shows that.