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Post by olroy2044 on Jun 1, 2012 19:10:55 GMT -5
Dave, I must disagree with you. Bader lost his legs in an impulsive and foolhardy attempt to perform an aileron roll at naught feet, and hooked a wingtip. He was flying an aircraft not designed to perform such maneuvers, and was a relatively low-time pilot. This by no means takes away from his tremendous achievements later on in his career. Eddie Andreini, on the other hand, was flying an aircraft designed, and modified for unlimited inverted flight. He was stabilized in straight and level inverted flight, and performed no violent maneuvers while at low level. Upon completion of the pass, he smoothly pulled up, gained sufficient altitude, then gently rolled the aircraft over. This maneuver was practiced extensively, and has been flown literally hundreds of times. Is it dangerous? Of course it is, but no more so than pushing a race car around an oval track, in tight quarters with other cars, all traveling at speeds that Andreini's Super Stearman can only dream of! Mik, on the next pass, Eddie flew inverted under the ribbons and cut them with his wheels. Roy
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photax
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Post by photax on Jun 2, 2012 2:09:53 GMT -5
Roy,
Have many thanks for your explanations, that`s a very impressing aerobatic manoeuvre ! I`ve once seen a biplane pilot flying overhead bursting ballons in the air, but this one is really exciting.
MIK
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Post by olroy2044 on Jun 2, 2012 10:06:25 GMT -5
I apologize for the lack of technical quality in the photos. Lighting conditions were DIFFICULT, to say the least. The viewing angles, which were dictated by the physical layout of the airfield, meant that we were looking directly into the late afternoon sun. It was difficult to see the aircraft, let alone photograph them. Better results were beyond my abilities, both with a camera and the computer. I shudder to think of the time I spent on my photos from that day hunched over a majic box, muttering arcane incantations, waving my arms in an attempt to get the attention of Wilber (those of you using Gimp are familiar with Wilber) and imbibing copius amounts of caffeine-laden dark and steaming beverages--------------all to no avail!
Perhaps someone with better access to the electronic spirits would have better luck, but I surrendered!
Roy
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daveh
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Post by daveh on Jun 2, 2012 10:28:25 GMT -5
Roy, my very stupid thing to do was really only a means of leading you on do a double-letter header as had happened with, I think, Doug's entry just before. It was meant to be taken too literally. That said, one small slip or the "driver" having a heart attack or suchlike and at least some of the five people could have been wiped out in an instant. Here's the video of it: : wonderful.
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Post by grenouille on Jun 5, 2012 4:36:54 GMT -5
In spite of lighting condition, that was some shot, right place , right time, precision timing and in the right hands, Cheers
Hye
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Post by olroy2044 on Jun 7, 2012 12:16:43 GMT -5
Thanks, Hye. Still not being satisfied, I downloaded the auto HDR application that the Barbarians use and ran the photos through that. When Auto HDR got finished, I opened the files in Gimp and tweaked the color (colour! just for you Dave ;D). Here are the results. I don't know if they're any better, but you certainly can see the details better. Need more practice with this The first one is not bad, the second---not so much--overcooked! Neat little application, Doug. Thanks Roy
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daveh
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Post by daveh on Jun 7, 2012 12:34:22 GMT -5
Roy, thank U!
That is how HDR should be used, I believe. So many totally overdo it and the end result looks fake. Excellent result.
Dave.
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mickeyobe
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Post by mickeyobe on Jun 7, 2012 15:22:28 GMT -5
My high school understanding of an airfoil was that the wind moves faster over the convex upper surface of the wing hence the air becomes thinner and creates lift. Pretty clear even to me.
But why doesn't turning that wing upside down suck the plane downward?
Mickey
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Post by olroy2044 on Jun 7, 2012 16:40:58 GMT -5
Mickey, an airfoil's lift while inverted is less a function of the shape of the airfoil, and much more a function of something called "angle of attack." In the photos, note the exaggerated nose-high (or tail-low) attitude of the aircraft. This is not because the aircraft is climbing, but rather because that is how the aircraft changes the angle of the wing traveling through the air. Lift is produced more by higher pressure air pressing on the bottom of the wing, rather than lower pressure "sucking" the wing up. Here's a quick and very dirty sketch to show it: (an aeronautical engineer I'm NOT!!) By positioning the aircraft in the extreme nose-high attitude, the "angle of attack" is increased to the point that the aircraft flies quite well inverted. It takes more power to sustain inverted flight due to the much higher drag created by the high angle of attack. In modern high speed aircraft, the airfoils are much more symmetrical, and rely almost exclusively upon angle of attack to generate lift. Modern jet fighters fly virtually as well inverted as right side up. Clear as mud now? Quiz tomorrow! ;D Roy
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mickeyobe
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Post by mickeyobe on Jun 7, 2012 19:49:20 GMT -5
Roy,
Thank you. Yes it is quite clear. The wing is being pulled and pushed up rather than just pulled up.
I found this on google to help me remember this lesson.
Mickey
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Post by olroy2044 on Jun 7, 2012 20:54:15 GMT -5
;D ;D
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Post by Peltigera on Jun 8, 2012 13:45:09 GMT -5
I've been worrying about the same thing for 50-odd years. nice to finally know why.
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Post by barbarian on Aug 24, 2012 21:54:22 GMT -5
The airfoil depends on Bernoulli's Principle, which states that the pressure of a flowing fluid is inversely proportional to the speed of the fluid. Air flowing over an airfoil moves faster along the curved section than the straight section, which lowers the pressure and creates lift as the higher pressure on the bottom of the wing pushes upward.
Roy is right; modern aircraft depend almost entirely on angle of attack; the air flowing across the wing is forced downward, which brings Newton's third law into play; the force of the air downward produces an equal force upward on the wing.
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mickeyobe
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Post by mickeyobe on Aug 24, 2012 22:23:15 GMT -5
And I thought I finally understood it.
I'll wager that Bernoulli character never had an apple fall on his head.
Mickey
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Post by barbarian on Aug 24, 2012 22:30:44 GMT -5
BTW, AutoHDR has a "natural" option, which greatly reduces the "HDR Look." Mrs. Barbarian prefers that option, and her shots are much more subtle; the dynamic range is increased, but the "grunge" look is absent. I like the subtle approach myself. Although this program does not produce true HDR images, it's flexible enough to produce a wide variety of effects. If you're shooting digital, you can do an HDR of action by taking a RAW image (which covers as much as 9 stops of exposure) and making different JPEGs of that shot, and then recombining them with HDR software. I like it for birds, especially those with white plumage.
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