flyer88
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Flyer88
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Post by flyer88 on Feb 3, 2009 3:20:39 GMT 1
I hear it's supposed to assist during landings to lower stall speed and give you added aileron control at lower speeds. In the real plane it reduces it by 12-15 mph Okay....I was bored today !  Glenn  |
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Post by aeroscout on Feb 3, 2009 3:34:28 GMT 1
Ok, I need details!!!!!!
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flyer88
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Flyer88
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Post by flyer88 on Feb 3, 2009 3:51:39 GMT 1
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Post by flydiver on Feb 3, 2009 6:10:13 GMT 1
There is no tip stall, there is only stall > then the wing falls over an everyone calls it tip stall.
So, you INstalled them. Tell us how they work out.
FWIW the Cub had very little wing stall. It also has poor glide. Don't know if those are correlated or if these devices will make any appreciable difference.
Watch out for placebo effect.
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flyer88
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Flyer88
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Post by flyer88 on Feb 3, 2009 6:33:49 GMT 1
I fully agree with you Flydiver. These VG's are not tapered like the real thing so I doubt they will do anything. Although I did run a small strip along the whole leading edge (in the middle of the red stripe) of my wing today for a experiment and almost crashed due to poor lift on take off then it stalled on landing approach and fell to the ground from about 5 feet up. I was completely amazed at how much that small strip effected the plane.
( Discovered that my servo for my elevator and rudder were loose and floating around in the fusalage, that's why she pitched over !)
Glenn
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Post by aeroscout on Feb 3, 2009 12:35:52 GMT 1
Thanks for the link, but I understand the reasoning behind vortex gen's. I'm an A&P/IA with 24 years of experience. I was looking for details on your install!!! - Source - Material - Flight testing ect. ect. |
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flyer88
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Flyer88
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Post by flyer88 on Feb 3, 2009 16:16:58 GMT 1
aeroscout: sorry wasn't sure about the info you were requesting.
The material I used is 3/16 styrene T moulding available at most hobby stores in the train department. It comes in all shapes and sizes. They even have small U shaped channeling that would look more like the real thing. These were glued on with clear canopy glue and were spaced 3" apart.
I think this 3/16 is alittle large for a scale apperance , but smaller stuff is available. As far as location of the VG's ...I looked for the highest point on the wing while in level flight and positioned them there. I'm not sure of the proper position, but please feel free to advise if your aware of any.
Currently not aware of any changes in flight as I haven't flown it yet. I will do so today, as I have a day off to fly all day ! Looking forward to enjoying a balmy 10 C.
Glenn
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flyer88
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Flyer88
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Post by flyer88 on Feb 4, 2009 0:09:13 GMT 1
Well I can tell you all this, canopy glue doesn't hold up in the cold. Most of my VG's were gone when I landed. I guess it's back to the drawing board !! I don't even know if this is worth the effort , but what the heck !  Glenn |
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Post by tlyttle on Feb 4, 2009 18:19:05 GMT 1
Well, we are dealing with very low Reynolds numbers here, which means that most aerodynamic tricks that work on full size are a waste of time on a model. I suggest that VGs would simply add some drag, and not much else. My reasoning here goes back to a fad on sailplanes decades ago, the Hoerner/reverse Hoerner tip: A buddy had an Aquila (part of the design was the Hoerner tips), and it simply would not track straight at high speed. He tried everything (we were working up to the National team trials), and couldn't get rid of the wander on the speed run. He sawed off the tips, straight as an arrow, and faster to boot.
This is not to say that all full-size tricks don't work, but that that there is a big difference between full size aerodynamics and the airfoils we are working with. However, experimentation is good, and the SC is a very good test bed!
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flyer88
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Flyer88
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Post by flyer88 on Feb 7, 2009 3:03:40 GMT 1
Here's my revised VG's. Double the amount and one size smaller. Oh, and bonded with clear silicone this time ! I'll keep you posted.  |
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flyer88
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Flyer88
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Post by flyer88 on Feb 21, 2009 4:56:57 GMT 1
Since the last post I've flown the Cub many times and honestly can't find any improvement in the handling of the plane. they fly so well with ailerons that it's hard to get any better. They look cool, and get some attention....that's all! Glenn Since this last post I've flown the Cub in very cold conditions and the VG's has stayed put, so the silicone is working very well. We were flying off a piece of grass 12 ft around in our snow covered field and I was able to land the Cub and take off from this small piece of grass everytime, so maybe they do add a little more slow speed control ?? It was cool seeing a little HZ Super Cub bush flying. I'll try to get video next time. |
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Post by cokebuck on Apr 2, 2009 5:32:34 GMT 1
Nice experimenting. If you wanted to get all NASA about it, you could place 1" strings at each VG, mount a flycamone2 & video the air flow movement. As an Aero Engineer graduate some 25 years ago who never worked in the industry, my guess is that the effect of the VGs whether positive or negative is negligible considering the wing airfoil is so d**n stable as it is, but at least they look cool!
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flyer88
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Flyer88
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Post by flyer88 on Apr 6, 2009 0:37:58 GMT 1
Thanks cokebuck, I might just try that. I'm a goof for experimentation with these things. Thanks for the tip. I'll keep you posted, just waiting for the weather to improve.
Flyer88
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