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Old Jun 13, 2015, 09:46 AM
danielphantom is online now
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Once in a lifetime
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USA, CA, Temecula
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not a glider, but look at the wings--glider like

This just struck me as beautiful, and the wings just don't look like the typical jet liner.

here's the video--https://www.youtube.com/watch?t=172&v=KYbM-3E11Qo

Daniel
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Old Jun 13, 2015, 12:27 PM
Sailhigh is offline
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Do a search on the slope forum and you'll find there is already a 787 r/c glider available, also an A380.
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Old Jul 29, 2015, 11:31 PM
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There's a lot of money to be saved by making airliner wings more efficient. If you took a typical airliner and removed the engines and the fuel, it would probably make a great slope soarer on a mountain ridge in a hurricane. ;-

I heard that, even with the engines, the L/D of a jetliner may be something like 18:1.That's still 1500 fpm down if you're flying at 300 mph. I suspect that more recent ones do better and really old ones a little worse.

Ever read about the Gimli glider?
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Old Jul 30, 2015, 12:03 AM
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I love the wing on the 787. As both an aerospace engineer and a glider pilot, that wing design really floats my boat! There is a great video of a 787 practicing its' airshow routine, I think it may have been in Dubai? Let me see if I can dig it up.

Going to a full composite wing in the airline world is a HUGE step forward. Understanding how to certify composite structures, how to analyze/inspect them for damage and how to properly repair them to the level required for airline transport. Obviously Boeing thought it was worth it to get the performance, but wow what a commitment to a change in the way they conduct business!
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Old Jul 30, 2015, 10:55 AM
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So cool to see the winglets replaced by raked tips. Anyone know where to find a good read?
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Old Jul 30, 2015, 02:09 PM
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United States, HI, Kailua
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The airline that is kind enough (or nuts enough) to employee me added winglets to their B767 several years ago, a spendy little project. Why?

300,000 gallons less fuel needed per year. That's something upwards of $4M.

Per plane!

Wow.
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Old Jul 30, 2015, 02:38 PM
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Quote:
Originally Posted by dayhead View Post
So cool to see the winglets replaced by raked tips. Anyone know where to find a good read?
Found one: https://www.facebook.com/atpltheory/...86422511385684

ATPL Theory
August 16, 2012
Raked wingtips vs Winglets
There are four aircraft that use raked wing tips: The Boeing 767-400, 777, 747-800, and the 787. There is one thing all these aircraft have in common: They are ultra-long range (6500 nautical miles plus).
Raked wing tips are more efficient in ULTRA LONG cruise segments. Whereas other wingtip treatments like winglets are more efficient in climb. Winglets do reduce drag, but they actually generate a bit of lift due to the way in which wingtip vortices strike the leading edges of the winglet...but that only happens to a significant degree when the wing is at higher angles of attack....like in climb configurations. Aircraft with winglets are shorter range...like the 737. It makes more sense and saves more fuel to optimize the climb and approach segments than it does to try to optimize the cruise phase of the flight. That might seem counter-intuitive, but Boeing engineers proved the math.
Raked wingtips on the other hand don't generate lift...what they do is reduce drag in a special way...by redirecting wingtip drag (vortices) farther outboard and aft of the rest of the wing... and it also redistributes the lift across the entire wing (called wing loading). The result is that they work in ultra long cruise segments. They don't depend on wing angle of attack, and they reduce fuel consumption when engine power is already set to cruise.
Short answer is winglets and raked tips both reduce drag and extend the range of an aircraft. But they do it in different ways...and which way is best depends mostly as a function of cruise flight time.
Thanks to the person who wrote this clear explanation!
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