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Vortex Generators

18 posts in this topic

Posted

Think I'll leave those to somebody else. Getting too old to have the crap scared out of me anymore. I do enough of that by accident. A stall speed in the low to min thirties is good enough for me.

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Posted

If having fun playing with stalls scares the crap out of you then perhaps flying aint your thing.  He is talking smack for the benefit of the video and to over sensationalize it just like ever other youtube sensation.  

Also remember that this is on the KF 7 wing that has a different airfoil than the early model KF.

The most benefit you will see from the VGs is probably when you yanking and banking as most pilots I know or have seen don't or wont drag the plane in way behind the power curve at high angles of attack.

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Posted (edited)

Stalls, spins, unusual attitudes doesn't bother me in the least way. Nothing scary about stalls at all. A spin 300' off the ground, maybe!  I would really like to see what leading edge slats would do on a Avid/Fox. And what benefits a AOA indicator could show on a "classic" Avid/Fox. After almost forty years of flying, if it ain't my thing, I made a boo boo a long time ago!  Some take comments too seriously!

Edited by Allen Sutphin
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Posted

I was referring to the guy in the video over playing how "scary" a stall was

:BC:

 

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Posted

I was referring to the guy in the video over playing how "scary" a stall was

:BC:

 

I guess some are afraid of the stall/spin situation. Suppose they figure that if I don't stall, I won't spin.  Could be in for a surprise some day!

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Posted

Ya know, I didn't get the impression at all that he thinks regular stalls are scary.  He simply stated that is possible to change the flying characteristics in a negative way using vg's and that is what he did and it scared him. It sounds like they tested a whole lot of different configurations and some of them were on the dangerous side.  Having watched other videos by different individuals that emphasize the same point I don't see why he's getting dumped on. 

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Posted

Pretty harsh criticism guys.  I found the video to be informative and presented a well thought out and well executed series of tests,  including their results and evaluation criteria. 

I agree with Willja67 that he was commenting on a stall test in which they had installed vortex generators in such a way that it aggravated the stall characteristics drastically enough that they almost created an unrecoverable spin condition.

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Posted

Maybe my comment was a bit harsh but I cringed when the grown man in the video said how scary it was to hold his plane in a stall. And then nothing happened. If he was scared the plane was prone to entering a spin, let's not be making YouTube videos and instead focus on flight testing the plane. I took his comment that he was scared to hold the plane in the stall. In that case, he'd best go talk to an instructor instead of the camera in the plane.

 

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Posted

It might well be that he got himself into trouble in the type of stall that he was demonstrating at the end of the video. Obviously the aircraft is now in a safe configuration but maybe he was thinking back to the incipient spin mentioned at the beginning of the video.

In any case giving people the benefit of the doubt goes a long way.  He was willing to share his experiences fitting vg's to his aircraft and there's valuable info in the video that benefits us. A few comments like the ones above and maybe he decideds not to post anymore videos. 

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Posted

Deleted my insensitive comment, but his impression remains. He had some really interesting testing but in my opinion could have presented it in a better way. There are some awesome videos on YouTube but maybe his are not for me. Thanks anyway for sharing!

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Posted

To each his own.  If you want to make videos do so, if you want to overhype them just like every other reality TV show or youtube sensation then you better be prepared for some feed back.  Doing VG testing is nothing new.  I have done it, big frickin whoop.  You stall and if you don't have the ball centered and keep the stick in your lap your going to spin.  That is flying 101.  To make a deal and talk about how scary it is just means that you are probably sporting a man bun and fly tricycle gear planes :lmao:  

Yes some of my comment is in jest as I can't believe how twisted up some get over things like this.

:BC:

 

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Posted

It was the "duchebag" comment I thought was over the top.  If you think the guy was overdoing it with the hype you were at least respectful expressing your opinion about it,  blunt but respectful.  

Why do I get worked up over situations like this? I just happen to believe common courtesy and just plain being nice to others  is important. Although common courtesy isn't very common anymore. If you're nice to others who will never meet you then you're more likely to be nice to those around you.  I guess I'm probably just out of touch with reality. Stepping off the soap box. 

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Posted

You're right, it was a rude comment that should not have been posted. I shouldn't have lowered myself to name calling.

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Posted (edited)


I just wish he had been more explicit about what placement he thought was so dangerous?  I placed my first set at about 7.5" back from the leading edge and all at very tight spacing.  It didn't seem to do much to lower the stall but gave better aeleron control.  The stall was still very docile and I could just hold the stick in my lap and it would just drop the nose a little until it gained flying speed and then come back up over and over again.  On the next set of wings, they have less that 1/2 the washout; I moved the VG's to 1.5" from the leading edge and spaced them very tight on the tip 1/3 of the wing and the next more open spacing in the inner 2/3 of the wing.  I think they work a little better to slow the stall and are just about the same for producing a gentle stall.  I can hold the stick all the way back and it will just cycle as it stalls and then flies again. The first wing was without and then with a KF cuff.  The second wing has a KF cuff.  I also tried VG's on the under side of the first wing and could tell no difference in performance or stall.  I also placed them on the underside of the HS ahead of he elevator and that improved elevator control.  Where in the world did he put these to make the stall so dangerous?   The only thing I have done that makes the stall more abrupt and the cycles a lot longer was to increase my flap travel from factory recommended 13 degrees to 26 degrees.  At the max flaps of 26 degrees, the stall is more abrupt with more vertical longer cycles.

Edited by SuberAvid

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Posted

Where in the world did he put these to make the stall so dangerous? 

A gentle stall progresses from inboard to outboard. The tip stalling first is what you don't want. He could have placed the vortex generators only on part of the wing. For instance if he placed them inboard but not outboard  the VGs would delay the stall at the root but the tip remains unchanged. This could have resulted in the tips stalling first. Just one possible scenario but there could be others.

 

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Posted


Didn't watch the vid but my research showed that it really wouldn't help the heavy hauler wing.  I did install them underneath the vert stabe 2" fwd of the elevator and found that it increased the elevator authority at stall which was a welcome improvement.

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Posted

VGs sure helped my Heavy Hauler wings. First installed under horizontal stab, yep good improvement there. Later did the wing, no numbers but at my 1000' strip with trees around the pucker factor was definitely improved.

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