Winglets

Richard

Richard

Final Approach
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I have the lingering notion that too bad we can't just shed the wings. Perhaps it's time to rethink the lifting body design.
 
Richard said:
Soon after I became aware of blended winglets I wonered where it would stop. Apparently, that point hasn't yet been reached.

http://www.flightglobal.com/article...-scimitar-tips-now-flying-on-hawker-800s.html

Question: What would be the expected mx costs associated with the new design? I wonder if the new design simply results in increased mx while achieving marginally (0.05%) increased aerodynamics.
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Not to be a stickler on accuracy, but the article claimed 0.5% improvement. Still very little short term...:rolleyes2:
 
airbornejohnny said:
Not to be a stickler on accuracy, but the article claimed 0.5% improvement. Still very little short term...:rolleyes2:
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The link in George C's post included a claim of 6-10%.

EDIT: Duh! I completely misread Dart's post. Hey, what's a decimal place when talking of OPM? :rolleyes:
 
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tonycondon said:
pretty significant when you're burning a lot of gas though.
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Now what do I do with the notion where a 0.5% reduction is pretty significant when talking of fuel consumption but it haint no thang when talking of the federal budget?

Maybe an engineer's perspective is needed rather than an economist's.
 
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Richard said:
I have the lingering notion that too bad we can't just shed the wings. Perhaps it's time to rethink the lifting body design.
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VariEz, LongEz, etc. The whole thing is basically part of the wing and flies fast for peanuts.

The problem is you have to learn to lay up fiberglass and have a place to do it.

Why hasn't someone made a commercial variant? Is this yet another example of the FAA certification process hog-tying the industry? (Just a guess.) Insurance?

Note that many LSAs are composite but look like the 50 year old designs, and few look like Rutan's? Why?
 
perhaps because canards are more efficient on paper than they are in real life?
 
I suppose I wonder why it would increase maintenance costs? Wings don't require a ton of maintenance, beyond inspections. When you're talking about something that goes over 400 kts, I could see it being useful. Lower fuel consumption or higher speed are both nifty.

That said, I think these things look silly.
 
tonycondon said:
perhaps because canards are more efficient on paper than they are in real life?
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Rutan's canards did not have landing flaps. They are difficult to engineer into a canard, because the canard wing needs them as well as the main wing, and they have to be coordinated between the two. Thus they have higher landing speeds than allowed by certification.
 
denverpilot said:
Why?
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Marketing. Everyone knows what a plane is supposed to look like. When you start moving pieces around and put the tail in front and the rudder out at the wing tip and the engine in the back and...well, forget that! But hey, swept vert stabs look sexy! even though they be less efficient.
 
Richard said:
Marketing. Everyone knows what a plane is supposed to look like. When you start moving pieces around and put the tail in front and the rudder out at the wing tip and the engine in the back and...well, forget that! But hey, swept vert stabs look sexy! even though they be less efficient.
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or the downwash from the canard downloads the inboard portion of the main wing, negating any efficiency advantage that the canard provides and driving weight into the structure that would otherwise be unnecessary
 
Ted DuPuis said:
I suppose I wonder why it would increase maintenance costs?
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I'm thinking the effects of torsion and 'flutter-like' (oscillation?) vibration resulting in fatigue. Look at the Spiroid winglet, how is it supported along it's length? Does it have a spar that has a life limit? How does such a spar--if installed--limit torsion? I imagine there is a moment that wants it to pitch backwards so the attachment has to be designed more than just a few rivets and epoxy or what have you. Then perhaps there is more wiring, etc. And it's always easier to construct and maintain a flat panel than a radiused panel. Winglets by definition are radiused. It is a rather complex design.

And how does it fly in a turn? Does it place restictrions on maneuvering? Etc....
 
Richard said:
Pretty spiffy design. Here the claim is 6-10% decrease in fuel consumption. Increased 'savings' = increased mx costs? Reduce the drag penalty and put the 'savings' into mx labor? Drive down labor costs to show real savings.
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I don't think the winglets will cause much, if any, increased Mx cost. No moving parts, and all the things you mentioned should be addressed in the design.

tonycondon said:
or the downwash from the canard downloads the inboard portion of the main wing, negating any efficiency advantage that the canard provides and driving weight into the structure that would otherwise be unnecessary
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Well, since most wings have some washout anyway to prevent the stall from starting near the ailerons, wouldn't an increased washout be able to maintain an optimum angle of attack in the canard downwash?
 
flyingcheesehead said:
I don't think the winglets will cause much, if any, increased Mx cost. No moving parts, and all the things you mentioned should be addressed in the design.



Well, since most wings have some washout anyway to prevent the stall from starting near the ailerons, wouldn't an increased washout be able to maintain an optimum angle of attack in the canard downwash?
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the story i heard was that a certain canard pusher showed major downloading on the main wing in (probably maximum Cl) manuevers, not sure about normal flight.

tweaking washout might prevent that particular problem but could screw up the wing for things like going fast. stall characteristics aren't as important in a go fast as stink design like many canard pushers. you've already got swept wings and fast airfoils, it's not going to have the stall of a 172.

too much washout and when it wants to go fast now you have the tips downloaded
 
tonycondon said:
the story i heard was that a certain canard pusher showed major downloading on the main wing in (probably maximum Cl) manuevers, not sure about normal flight.

tweaking washout might prevent that particular problem but could screw up the wing for things like going fast. stall characteristics aren't as important in a go fast as stink design like many canard pushers. you've already got swept wings and fast airfoils, it's not going to have the stall of a 172.

too much washout and when it wants to go fast now you have the tips downloaded
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plus the main wing is supposed to be impossible to stall anyway so who cares ;)
 
Richard said:
Soon after I became aware of blended winglets I wonered where it would stop. Apparently, that point hasn't yet been reached.

http://www.flightglobal.com/article...-scimitar-tips-now-flying-on-hawker-800s.html

Question: What would be the expected mx costs associated with the new design? I wonder if the new design simply results in increased mx while achieving marginally (0.05%) increased aerodynamics.
Click to expand...

From the article...
feature is expected to reduce drag by another 0.5%
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Half a percent drag reduction is a lot. It's not a moving part is it? It's just a more efficient tip design.
 
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