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Old Mar 06, 2008, 07:42 AM
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Joined Nov 2007
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Side force generators good, bad, neither?

There is an interesting thread in sailplanes about winglets (the name used by the aerodynamic engineers for side force generators). Two points seem clear about these devices toe out is the key feature and they reduce drag.

In the world of aerobatics and 3D flying, my understanding is that they increase stability in high alpha maneuvers. The penalty is the plane does not yaw as well. I am guessing the only class of maneuvers where this is unwanted is in spins. Similarly, SFGs should reduce tip stalls.

The other big difference between sailplane winglets and SFGs is that SFGs extend downward also. I assume this is so that they work equally well inverted as right side up.

Do the 3D folks have opinions about these?

I have a new Funtana which I will try with and without SFGs. I am also planning on making my own. Initially I thought just making them smaller would be tried. But after reading the sail plane thread I am thinking putting a real airfoil on the SFGs might be my first step after seeing the differences with and without.
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Old Mar 06, 2008, 07:51 AM
3DHS Junkie
800mZero's Avatar
Rhode Island
Joined Jun 2005
5,683 Posts
Quote:
Originally Posted by JohnBoy07
There is an interesting thread in sailplanes about winglets (the name used by the aerodynamic engineers for side force generators). Two points seem clear about these devices toe out is the key feature and they reduce drag.

In the world of aerobatics and 3D flying, my understanding is that they increase stability in high alpha maneuvers. The penalty is the plane does not yaw as well. I am guessing the only class of maneuvers where this is unwanted is in spins. Similarly, SFGs should reduce tip stalls.

The other big difference between sailplane winglets and SFGs is that SFGs extend downward also. I assume this is so that they work equally well inverted as right side up.

Do the 3D folks have opinions about these?


I have a new Funtana which I will try with and without SFGs. I am also planning on making my own. Initially I thought just making them smaller would be tried. But after reading the sail plane thread I am thinking putting a real airfoil on the SFGs might be my first step after seeing the differences with and without.
head over to the 3dhs velox thread--the plane has SFG's and with them on there is no ill effects---bunch of vids there. They really are nice in knife edge.
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Old Mar 06, 2008, 08:53 AM
Aerodynamically challenged
3Deranged's Avatar
3D World, Florida
Joined May 2005
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I'm kind of an SFG nut too. They work so I use them. Here's a few planes I've had with them on. They do help with high alpha stuff, rolling manuevers, and KE of course. Some people hate them, can't understand why. They help you out! "But they're not scale" is one excuse I've heard for not putting them on. Hate to break it to you but most planes aren't scale either!
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Old Mar 06, 2008, 10:29 AM
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Joined Dec 2005
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The Yak already looks weird enough without the SFG, but with them it's weird enough to be cool.



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Old Mar 06, 2008, 11:08 AM
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Joined Jun 2004
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I used them on foamies before. They work fine but I like the feel without them better, plus they can make any plane look weird (specially when they are huge).
Leave the winglets to B-jets.
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Old Mar 06, 2008, 11:27 AM
Yes, right there.
SpleenRippa's Avatar
Comox, BC, CAN
Joined Jul 2003
581 Posts
Quote:
Originally Posted by JohnBoy07
There is an interesting thread in sailplanes about winglets (the name used by the aerodynamic engineers for side force generators). Two points seem clear about these devices toe out is the key feature and they reduce drag.

In the world of aerobatics and 3D flying, my understanding is that they increase stability in high alpha maneuvers. The penalty is the plane does not yaw as well. I am guessing the only class of maneuvers where this is unwanted is in spins. Similarly, SFGs should reduce tip stalls.

The other big difference between sailplane winglets and SFGs is that SFGs extend downward also. I assume this is so that they work equally well inverted as right side up.

Do the 3D folks have opinions about these?

I have a new Funtana which I will try with and without SFGs. I am also planning on making my own. Initially I thought just making them smaller would be tried. But after reading the sail plane thread I am thinking putting a real airfoil on the SFGs might be my first step after seeing the differences with and without.

I had always been under the impression that winglets and SFGs were two totally different things. I mean, IRL aren't winglets used to eliminate/lessen vortices spiraling off wingtips?
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Old Mar 06, 2008, 11:34 AM
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United States, PA, Lancaster
Joined Jun 2003
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Application, application, application. An aerodynamic feature can be either "good" or "bad" depending on the application. Look at EDFRules post above and you'll see something important - lots of testing on lots of different models - and notice that he is a fan of SFGs. This is a trend we see again and again: Those people willing to do a lot of testing tend to find the setups that make them happy.

So, my advice: Experiment! Handy tip: Analyze your airplane 90 degrees off from what we normally think of as "up". Treat your SFGs as wing surfaces, and do all of the analysis you would normally do for a wing.
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Old Mar 06, 2008, 04:13 PM
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United States, GA, Byron
Joined Mar 2007
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Yes, it all depends on the plane. I like SFGs, and on most all foamies I get, I end up cutting out some SFGs, and taping them on, just to see how it flies. On some planes it really helped alot, and some made it worse. And some plane already have SFGs, and I add more!

Also, I dont just try SFGs on one part of the wing, I usually end up trying them on differint places on the wing, and even some on the tail.
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Old Mar 06, 2008, 07:04 PM
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to hardcore 3Ders they're bad, but for hybrids and precision guys, they're great!

helps alot with slow flight and knife edge =P
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Old Mar 06, 2008, 07:15 PM
There is no place like Hodges!
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United States, GA, Byron
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Quote:
Originally Posted by brian94066
to hardcore 3Ders they're bad, but for hybrids and precision guys, they're great!

helps alot with slow flight and knife edge =P
I am a hardcore 3Der, and I like them. Makes the plane lock into a hover!
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Old Mar 06, 2008, 09:06 PM
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I've been using my thumbs to lock into a hover,how will the SFG help?I'm new and don't know a lot about aerodynamics.Olin
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Old Mar 06, 2008, 10:00 PM
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3D World, Florida
Joined May 2005
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If I am to believe the testing I've done, my theory is that with closer inboard SFG's(midwing) help out on certain shaped airframes by channeling the propwash more evenly back across the fuse and tailfeathers instead of the flow dispersing. Outboard(wingtip) SFG's help cup the air on the end of the wing not allowing it to curl off the tip and channeling it rearward. Ben is correct, it takes a lot of different shapes,sizes and positions to find the sweet spot. But when you do, you'll wonder why you haven't used them more. Also have tried CPLR's "Canalizer" T-wing and that also has some positive channeling effects for the rougher airflow over most cockpits. He says it takes the swirling airflow off the prop and straightens it up after it curls over the canopy area resulting in better airflow over the tailfeathers. QQ also used them on his Brio. Not saying all these aerodynamic devices are needed for every pattern/3D plane but I always look to improve an airframes' performance. And if all it takes is a few pieces of balsa or foam then you can bet I'll try it.
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Old Mar 06, 2008, 10:14 PM
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Edfrules,I see you have really spent some time working on it,I find it fascinating.Seeing all that might just of got me to start experimenting myself with my CR-1.Olin
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Old Mar 06, 2008, 10:46 PM
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Experimentation is what progresses the hobby. That's why I keep coming back for more, there's always something else to learn or improve. You know the old saying " If you've met your goals-you've set your sights too low".
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Old Mar 08, 2008, 12:49 PM
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Grass Valley California
Joined Jun 2004
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Scale? The full scale guys are watching us! do not be suprised to see side force generators in full scale

Already on the Python,and some other full scale biplanes. Look at the struts and tell me that they are not sideforce generators.

Maybe in the Red bull series, as fast as they have to go and as much knife edge as they fly side force generators may make it easier for them,Less angle of attack on knife edge

Dennis
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