To answer the question my fellow OZ ark asked..
I found anything forward of the highpoint was less effective compared to on or up to 1 " back from the high point. I run mine 1cm back from the thickest part of the wing @ my CG, My theory is they work best at the CG.
The direction they sit in relation to the airflow or the forward LE sweep I found didn't make any noticable difference.
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Now onto the "debate"
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Its fair to say that Vortex Generators work. I've done more testing of these things than I care to remember, and more elite racing event are starting to employ some form of drag control. Remember those racing suits the swimmers were wearing to break multiple world records that are now banned ? They were dimpled like a shark skin. Formula 1, Red Bull Air Racing, golf - it doesnt matter - they are looking into ways to CONTROL AIRFLOW.
To say you're not looking into some form of boundary layer control simply means your not looking at every angle and seeking every advantage out there to make your planes fly at a 100% optimum level. ( Which is fine, its no different to practice if your having 50 flights a year or 500 - it reflects your commitment to getting better )
It seems to me, there are some that use them, some that don't - I've had a few conversations with Igor Burger about this exact technology ( why he does or does not use them) and he doesnt use them exactly, however DOES use Zig Zag tape located along close to the highpoint. Now I also know that the height of a Vortex Generator in our scale would work out to be close to 1/64th - So Im sure the ZigZag tape is working along similar principles to the VG's . I don't believe they are ( the Zig Zag tape ) simply disturbing the airflow, I think they are creating the same effect but in a more subtle way. How do I know this ? I've done back to back testing on both systems. My point isnt to say I think the VG's are better .. or Worse. My testing indicated to ME that the deployment of VG's had a more pronounced noticable effect on more segments of the pattern than the Zig Zag Tape. Now Igor is a true master and revolutionary thinker and dual World Champion - So his practice is also acceptable, just for me personally I found something that worked differently.
The point of my VG program was to develop them to be as subtle as possible - on my planes they are almost hidden. I also tried hard to develop them to a minimal setup that still gave 95% improvement compared to having them ALL OVER the plane.
I found NO IMPROVEMENT in running them on the stab - When I talk to those who ARE running them on the stab the consensus is "minimal improvement" almost to the point of subjective improvements. Which for me isnt enough, I need concrete ( lost 1/2 oz of tip weight ) obvious.
I never shouted out that I thought they were required to make Top 5.. and the fact that Paul Walker or Dave Fitzgerald or Doug Moon or any other "name" flier are using them... isnt relevant. What IS relevant is these are clinical minds and methodical approaches to flying Stunt and they win for a REASON. VG's are not the reason but they are a byproduct of that reason - commitment to improvement.
Its pretty simple really : There is NO ONE RIGHT WAY. Electrics / Pipes / Igor Timers or PA 75's - Whatever I need to build which will help ME put the model in the right places more times than the other guy is what I want.
Derek : I was on your circle at the Nats and felt I put up some DAMN good flights and you eclipsed me by 20 something points, which was an impressive display. You build light and straight and in general are a Top flier and worthy of a Nats crown. Your views are respected by many, I certainly respect ( and agree with) some of your views and stances on many of the topics you advocate. However It would be nice if you TESTED them on your own plane with your OWN flying style and then made a judgement call on their effectiveness for your program.
Sparky : " When Brett Buck has concrete evidence they work and they are on his airplane I might think about it "
That's an indication of many MANY things ... however I will just leave you with a small snipette of basic personality psychology 101.
Conformity = A change in behavior or belief as a result of real or imagined group pressure.
2. Types of conformity
A. Compliance. Publicly acting in accord with social pressure while privately disagreeing. This term best describes the behavior of a person who is motivated to gain reward or avoid punishment. On the level of compliance, many experimenters see little difference between animals and humans, because all organisms respond to rewards and punishments.
B. Identification. As with compliance, we do not behave in a particular way because such behavior is intrinsically satisfying. Rather, we adopt a particular behavior because it puts us in a satisfying relationship to the person or persons with whom we are identifying. We do come to believe in the opinions and values we adopt, though not very strongly. We want to be like some particular person.
EX: Want to be just like your father.
C. Internalization (or acceptance). Both acting and believing in accord with social pressure. This is the most permanent, deeply rooted response to social influence. Internalization is motivated by a desire to be right. If the person who provides the influence is perceived to be trustworthy and of good judgment, we accept the belief he or she advocates and we integrate it into our belief system.
There are COUNTLESS articles on the psychological aspects of conformity... and how that differs from being a free thinker and innovator.