High-AOA Wobble

[C140]

I've noticed lately that my E-Flite Divo has just a touch of wing rock when transitioning to hover or when trying to hold a post stall attitude. I'm not sure if it's a new problem or I just never noticed, but it's got me curious on how to fix it. It seems like a span-wise flow issue, so I'd just drop a stall fence right in the middle of the wing. Is that the right way to go about it? I've noticed several of these 3D aircraft with them (yellow circles), although I'm not sure if they're to fix this particular issue.

[pstrdenver]

Crash, admittedly I know nothing about this matter but in my ignorance I always thought those were SFG's for better tracking and to add surface for better KE's.

Now you've given me something to research. Thanks. ( read sarcasm)

[EDFrules]

Not sure how to fix the Divo issue. Sometimes this is caused by a little too much weight on the airframe. Otherwise it can be sometimes chaulked up to the airframe desgin or pilot induced osicillations. QQ certainly knows how to design airframes so I can't think it might be that. Experimentation is the best way to find out what works best for you. I use SFG's on most of my planes...OK well all of them LOL. They also help in the rolling manuever dept. as well as high alpha fun. SFG's are not a cure all but should be integrated into the design. That being said I would stick them on my kids and dog if they would hold still long enough. My 87" Extra doesn't really need them either but it provides better KE loops and harriers. Just makes it that much smoother. I've added them to airframes that exhibit a little too much wing rock for my liking and usually this helps reduce WR and makes harriers a lot more fun. They take some playing around to get the size and location correct. Trail and error is what the aerodynamics game is all about! My .02 Here's some vids to show how nice and smooth they can make a plane fly-works for bipes too:

3DHS Extra 300 SHP 87 inch

click here to watch the video

RC Electric Airplane: Clik-X 2008 Year of Fun!

http://www.youtube.com/watch?v=UJ1Pi8nhvtE


Jason

Originally Posted by Crash&Burn(Often)

I've noticed lately that my E-Flite Divo has just a touch of wing rock when transitioning to hover or when trying to hold a post stall attitude. I'm not sure if it's a new problem or I just never noticed, but it's got me curious on how to fix it. It seems like a span-wise flow issue, so I'd just drop a stall fence right in the middle of the wing. Is that the right way to go about it? I've noticed several of these 3D aircraft with them (yellow circles), although I'm not sure if they're to fix this particular issue.

[C140]

I'm about a quarter ounce heavy, so that might be it. It finally calmed down, so I'm going to go and try my first version of fences right now.

[max-nix]

Try rounding & smoothing the wing leading edge.

[C140]

My fences worked out just how they were supposed to. There was no transition between flying and hovering and it seemed like it tracked surprisingly well. The problem is I don't know if I really like it. It's almost too precise. I might have to scale back the size of the fences a little to make it fly how I want it.

[EDFrules]

It's an old carpenters joke:" I cut it 3 times and it's still too short". Better to make your SFG's too big-you can always cut them down. It always takes some flight testing to figure out placement and size of SFGs to get it to where you like it. The Tribute FX 3D wasn't the best flyer until we played around with SFGs and fences and once the right combo was found, it was a whole different flying airframe. Glad it's working out for you. Nice to see that some folks are willing to experiment instead of giving up on an airframe and living with undersirable flying traits.