Ted, Jim Aron, Peter Deane, and I went flying this weekend. Since it had been a topic of discussion, and since we hadn't tried it for a while, Ted and I set up the circle with some 45-degree markers. The layout was largely as shown in the "parallax" thread. The radius of the markers was 90 feet. In case someone else wants to try, the straight-line distance between the markers for a 90-foot radius is 68',11". We only did a few on the nominal "downwind" side of the circle, but same idea.
Ted and I first both flew "regular" flights, and tried to mark or note the maneuver sizes. For the most part, we were A LOT closer to 45 than we thought or remembered from the Good Old Days. That's not to say we were very close. Ted and I were pretty close to each other, size-wise (with me probably a little smaller most of the time, but not statistically significant) and we were both in the range of about 15 feet over on loops, or about 53-54 degrees; about 20% over. The square 8's were also proportionally larger than spec, about 110 degrees vice 90.
When Jim flew he didn't seem grossly oversized compared to the average flight to casual observation. However, on measuring it, he was WAY over - 65-70 ish. He was having some trim problems and flying a different airplane so it really wasn't representative of his normal flight. But Ted and I have watched *a lot* of contest flights over the years, and Jim's size *did not* stand out as notably large compared to the average flight. It makes me wonder what a flight that *did* stand out as grossly over would have to be.
I also watched from the judges position, and the markers definitely did show the difference a lot better than just eyeballing it. The parallax situation with Ted's flight was pretty much exactly as the previous thread would have suggested. Ted's square 8 pretty much fell on the vertical lines extended from the + and - 45 markers. This is perfectly consistent with the slightly oversize maneuver combined with the parallax. Jims flight, which you could have almost not noted as gross without the markers, was *blatantly* oversized, not even close. Even with my minimal depth perception, it was really easy to tell it was not only outside the markers, but it was even further out than the marker suggested because you were clearly not on the right line-of-sight.
On Ted's flight, it was not nearly as clear that it was oversized due to the LOS issue. In some lighting conditions, like sunlight, you could pick up enough visual cues to see that the distance between the airplane and the marker was messing up the measurement. In flat lighting, it was not very clear at all. Once you had some calibration flights to get used to it, it wouldn't be all that difficult.
Of course, I can't tell you what mine looked like from outside.
We then tried variations on smaller. Shrinking it a little bit, down to 10' over or about 50-51 degrees, was not a lot of problem on slow flights, and induced some small errors that we both thought we could get around with some practice and re-trimming.
Shrinking it down to 45 was possible, but it was pretty challenging. I could do it pretty well *as long as nothing got the airplane upset*. Anything that got it "out of shape", like turbulence or wake, pretty much killed the rest of the maneuver. Once it got upset, it didn't have time to recover before the next corner, which just made it worse, and the whole thing sort of fell apart.
This really isn't all that surprising, if you think about it. The maneuver sizes are probably as small as we feel comfortable with on a regular basis. Everything is sort of "tuned" for this size, and the recovery time probably sets the minimum comfortable size.
I don't think 45 could be done on a regular basis with our (pretty decent) airplanes without significant changes to the trim and power. Certainly not without very significant compromises of shape and consistency. For certain, more emphasis on even more stable speed control and RPM control would be required. I got the impression that it would work a lot better with the old 1st generation 46 VF setup (big 2-bladed prop, very low pitch, and let-er rip RPM) than with the Harley-style runs we have now. You would also have to be very critical with roll trim and line-whip to minimize the upsets. This would of course trade off some "manufactured" line tension.
For what it's worth, based on Peter's Vector, I couldn't really see the slightly smaller airplane being a lot closer to the right size. As Brian mentioned to start the other thread, the maneuvers *are* physically smaller. That's doesn't necessarily mean that it's smaller in angular dimensions. The shorter lines enhance the parallax of course, and the combination my work well to camoflage the situation. This is with a Fox 40/10-6, so the maneuvers are subject to significant "energy management" limitations that may let you shrink it even smaller.
While it doesn't leap out at me that it will be an improvement, it would certainly be worth trying longer lines. If gives you more room, but it also would lower the line whip frequency and reduce the parallax, both of which tend to work against you. Longer, lighter lines would be ideal from a size control standpoint, but there's still a precision consideration.
Based on my eye, NOBODY competitive is flying very close to 45. It looked doable when we were at 50, but that last 10 feet really makes a difference.
Brett