Thread: Discussion XC#10 in a series, Giant Icon?
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Old Jun 07, 2010, 03:16 AM
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Originally Posted by G Norsworthy View Post
#8 is a success with a 7 hour 90 mile flight, a 1 hour LSF 5 flight in the bag, and countless miles on the road with a variety of pilots. Max altitude 1522m, a full yank from a dive twice, and plenty of landings on various surfaces with never a scratch on the T-tail.

#9 should be in the hands of a customer shortly and I expect great things.

Now it is time to sit back, slow down, and really think about what the next one will look like. I have one more fuse in the corner, and this should be it for a while. I can stop anytime. Really.

This design will be data and analysis driven. JW has patiently pointed me in the right direction over the past few years and it is starting to sink in. I'm not an aero professional but the tools are public and anybody stubborn enough to stick with it should be able to go through this design process.

I have some very interesting first look results but I need to clear something up before I go on. Does the max visible height scale linear with the chord or does it follow some other function? As a starter I took the fraction of a degree that a given chord takes up in a circle and plotted it against the altitude for three different chords. If my math is right it is not linear, and the higher you go, the more advantage the 14" (red) chord has. Will haze make this curve more linear, or worse yet, bend it the other direction, and does the amount of haze matter? Open for discussion.
my 2c. I think the most important thing for visibility is air quality and angle of the aircraft in relation to the pilot. I would not have thought my 50 something mark one eyeballs could see a 12" chord at over 5000 ft till I proved it to myself at the last Davis event. That had everything to do with the perfect air clarity that day and with the fact we kept our SBXC nearly straight overhead in cruise while that high up. When it is straight overhead (say within a 10 degree cone) you get the full benefit of the wide chord visibility when cruising or thermalling. When it is off to the side, say 45 degrees, for a given AGL you are not only further away in actual distance (hypotenuse of the triangle) but the angle of sight reduces the effective chord for visibility (bottom surface of wing is no longer perpendicular to the pilots eyes). a double whammy especially when there is crud and haze in the air like there is during the majority of flying days. and thermalling at high AGL and off to the side like that causes the plane to pretty much dissappear every half circle due to the angles. Now, we often dont have a choice when it comes to thermal location and end up following them off to the side many times but we do have a choice where to position the glider while in cruise and straight overhead is the safest place to be while at extreme altitude.

the problem I have with flying it directly overhead is it can become damned uncomfortable on my neck. I need a lazyboy recliner or something. two lazyboys bolted to a big flatbed truck.. now we're talking...
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