Originally Posted by puppypaws
You've never heard me tell everyone they could go out and cut grass at 15 mph, but I have said you can cut grass in the right conditions that fast, and some have chimed in and said they did the same.
I think you can look back, and I feel assured anyone reading this that knows me has heard me say many times that I can cut grass at top speed because of being on relatively smooth terrain, and having stiff blade dryer type southern grasses to cut. I have always advocated that northern limp blade grasses are much more difficult to get a clean cut on, and you can find statements I've made that if cutting much above 3" the XR-7 Hustler deck would not give a clean cut in northern grasses at any speed.
I have also said that the Exmark Ultra Cut deck performed best in northern grass due to its more powerful suction, but you would be forced to scrape the deck more often than a deck such as the Scag Velocity Plus deck with its hybrid tunnel design.
Now, for you to say that it is impossible to cut grass at 15 mph due to your calculations showing a lack of blade tip speed may be correct as you saw it on paper, but you cannot disregard the fact that several besides myself in this thread, and many more throughout LawnSite have stated they do cut grass at those fast speeds.
So now, if you will concede that yes, it is possible to cut grass in the right conditions at 15 mph, and your calculations may not be exact in a real world cutting scenario, I will concede that I agree with you.
in both this thread, and several others in which we've both posted in the past, I have said repeatedly that you can do it under the right conditions. Feel free to go back check for yourself. All I have said is that the numbers say it is not wise to do since the blade strikes per inch of forwards travel are so low. Many manu's advertise the high BTS's of their decks by including remarks such as "...more blades strikes per inch" etc, so I have to assume it's something they take into conmsideration. It's a factor they are certainly aware of and it helps them sell their product. Like I said, if you can do it, and are satisfied with the results, that's fine by me. I just don't think it serves the mowing community at large to post blanket statements that it is ok to do or that the cut bis going to be acceptable. It can be done, but only in the right conditions.