From: Robert Samuels <[EMAIL PROTECTED]> if anyone out there can give us some research based information on far a human can discern an object like a 3m sailplane I'd sure like to hear it.
============================== Well, it depends on lighting and contrast. For resolving front-lit objects like lines on a page, various sources say that the human eye can resolve a pair of parallel lines that subtend 1 or 2 arc minutes (let's say 2 to be conservative). That means that if you had two parallel lines 10 feet apart, the best human vision could tell that there were two lines and not a single line if the pair were 17000 feet away! When you look at stars against a black sky, you can resolve smaller arcs. Some exceptionally gifted people can resolve Jupiter and one of its moons, or the North Star and its twin (there are actually 2 stars there, 18 arc-seconds apart. There's a third too, but only Hubble can see it). But seeing a wing against the sky depends not on the span, but on the chord. If the chord is 1 foot, it will subtend 2 arc-seconds at 1700 feet. The contrast is better than that of front-lit lines on a page, of course, so the eye can keep going. At 3400 feet, the 1-foot chord wing subtends 1 arc-second. Only really good eyes can see that, and it will be dependent on the brightness and character of the background. As you go on from there, you're surely getting to the limit of most people's vision. Both Babe Ruth (on his best day) and Albert Pujols have been reported to have 20/7 vision, almost 3x as acute as that of the poor middle-aged glider flyer. Perhaps if you want an altitude record, you could catch Albert on his day off to help spot the plane. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off. Email sent from web based email such as Hotmail and AOL are generally NOT in text format
