Comments on: Tweets on a Plane! The Second Coming http://www.mediaite.com/online/tweets-on-a-plane-the-second-coming/ Mediaite Fri, 10 Feb 2012 17:58:00 +0000 hourly 1 http://wordpress.org/?v=2012.06 By: alex020588 http://www.mediaite.com/online/tweets-on-a-plane-the-second-coming/#comment-403709 alex020588 Fri, 08 Apr 2011 22:02:20 +0000 http://www.mediaite.com/online/tweets-on-a-plane-the-second-coming/#comment-403709 2011 new style !!! http://www.nike4world.com 2011 new style !!!

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]]> By: Vidiot http://www.mediaite.com/online/tweets-on-a-plane-the-second-coming/#comment-6580 Vidiot Tue, 13 Oct 2009 23:34:33 +0000 http://www.mediaite.com/online/tweets-on-a-plane-the-second-coming/#comment-6580 the reason you see the blades moving here when it's just a blur to the naked eye is an optical illusion. This springs from the sheer speed of the rotating propeller and the nature of video, which is made up of still frames. The props are rotating at about 850 rpm at cruise speed in a Q400 (which you'll be pleased to note is a Canadian plane, built by DeHavilland in Toronto -- it's the updated, much quieter version of a Dash-8). Because the prop is moving so fast -- about 15 revolutions per second, the prop moves just under half a revolution during each video frame (1/30 of a second.) With each successive video frame, the apparent position of the prop (since it's a symmetrical six-bladed prop) only has changed a small amount (even though it's rotating much faster than the video frame can show), so it appears that it's going much slower. For more on this, see Wikipedia's entry on <a href="http://en.wikipedia.org/wiki/Wagon-wheel_effect" rel="nofollow">the wagon-wheel effect</a>; it's hard to describe without diagrams and handwaving. the reason you see the blades moving here when it’s just a blur to the naked eye is an optical illusion. This springs from the sheer speed of the rotating propeller and the nature of video, which is made up of still frames.

The props are rotating at about 850 rpm at cruise speed in a Q400 (which you’ll be pleased to note is a Canadian plane, built by DeHavilland in Toronto — it’s the updated, much quieter version of a Dash-8). Because the prop is moving so fast — about 15 revolutions per second, the prop moves just under half a revolution during each video frame (1/30 of a second.) With each successive video frame, the apparent position of the prop (since it’s a symmetrical six-bladed prop) only has changed a small amount (even though it’s rotating much faster than the video frame can show), so it appears that it’s going much slower.

For more on this, see Wikipedia’s entry on the wagon-wheel effect; it’s hard to describe without diagrams and handwaving.

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