Sparky, I think it is time to start ignoring this people that like to argue. There is nothing like experience to learn something. Dad always told me to learn from other people experience and save myself some grief.
I would note that there is no real arguing going on in this thread. It's not a matter of opinion how this works, so there is no need to believe anything, nor to convince anyone. It's the most fundamental physics and math, it's not open to debate, so I am certainly not attempting to debate this. Why this topic was again brought up is anybody's guess, but it doesn't matter, since the facts don't change.
There are certainly many things in stunt that are not well-understood in an analytical sense, so anyone who says they do understand everything is certainly lying, and no one is claiming that here. This is not one of them, Isaac Newton never built or flew a stunt plane and he could have figured it out.
In terms of experiencing things, there are many things about stunt that can be learned from experience, and many that *have to* be learned by experience. But, in this case, no experience is required, you don't have to build any airplanes to figure it out. Most likely, if you are interested in proving points on this topic by building airplanes and seeing how they fly, you will learn either nothing about it, or the wrong thing. Since this is a "non-effect", what is likely to happen is that you will get very misleading results because the rest of the parameters of the experiment will not be controlled.
As an example - we know for sure that ~15 thousands of an inch of stabilizer skew with respect to the wing can cause an airplane to be untrimmable in some cases. So if you were to build airplanes with three different bellcrank pivot positions, the (non) effect of the pivot position will be utterly swamped by building and mass properties variations. Get the stab out of skew by .005" on one of them, and .005" the other way on another, and they will fly very differently, and the temptation will be to figure it's because of the effect you are looking for (bellcrank pivot) instead of the real issue, and the 100 other differences that you don't even know about.
Most any conclusion you might draw from pure experiment are extremely prone to misinterpretation like this. That's why the vast majority of what you hear by way of stunt folklore is either completely wrong, or right only assuming something not stated, or misinterpreted. One of the big changes over the past 25 years or so has been to spend some time sorting out the nonsense from the reality. And, in many cases, doing what your Dad suggested and actually learning something from someone else.
The latter has never been more clearly illustrated than it was in the early 90's. Paul Walker started beating the living sh*t out of everyone, so the extent that it seemed to get too easy for him for a while. What was amazing was how many people reacted to this. Did they go out and start building Impacts with 40VFs? Did they abandon "my airplane is 2 oz lighter so it's 2 oz better" reasoning? Did they start experimenting with smaller props? For many, the answer is no, they went out and tried to find bigger props, build the airplanes lighter yet, and kept sticking with marginal designs that had shown themselves to be behind the curve and made them even more extreme. Most people learned absolutely nothing from that, and still haven't. Other people did, and shared information, and dominated the thing for the next 20 years.
Many people in stunt have absolutely no interest or willingness to learn ANYTHING that contradicts their preconceived notions, and will go out of their way to do just the opposite just to prove they know better, even to their own obvious competitive detriment.
Brett
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