FastEddieB Posted July 20, 2016 Report Share Posted July 20, 2016 Roger Lee just posted this YouTube video to another thread, which I've bookmarked as a "Favorite". We have hashed out appropriate landing speeds ad nauseum, so this is not meant to convince anybody of anything, but to point out to students what I think is an important lesson. Every Sport Pilot and Private Pilot had to demonstrate a landing at approximately stall speed on his or her checkride. I was taught to use maximum flaps as consistent with conditions. That has held me in good stead for many decades, though I realize it makes some pilots uncomfortable, and may not be appropriate in all planes. Which leads one to ponder, how did it come about that the pilot in the video came to land in the manner he did? It sure looks to me like minimal flaps were used, and to be generous the landing looked to be at least 10 kts fast. How much energy is implied by an extra 10 kts? Step by step, assuming a full flap stall speed of 40 kts... 1) Divide the smaller number (40) into the larger number (50). The result is 1.25. 2) That means 50 is 1.25 times larger than 40, or 25%. But kintic energy increases as the square of that increase, so... 3) Square 1.25, or just multiply it by itself. The result is 1.5625 4) Expressed as a percentage, the plane landing at 50 kts has just over 56% more energy to dissipate after touchdown. Has to go somewhere, and you can see how some of it got dissipated in the video. As I said, I think assuming 50 kt touchdown speed in the above video is quite conservative. As an exercise, maybe compute the numbers as above for 55 or even 60 kts. Or at the other extreme, at just 45 kts. All assuming a full flap stall speed of 40 kts. I am not going to go back and forth with the "fly it on" crowd - we're all adults and can land in any manner and at any speed we choose to. But as the thread title says, I just did not want a teachable moment to slip away. Link to comment Share on other sites More sharing options...
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