As was mentioned earlier, we had Jim Aron's Chumley memorial stunt clinic weekend before last. Despite the heat (I got 109 at one point on my air density meter) and the wind on Saturday, I think we accomplished quite a lot. Names withheld unless someone wants to out themselves...
Saturday was a blowout, 20-25 at 7 in the morning is not promising. David and I declined to fly unfamiliar out-of-trim airplanes in these conditions, so David went to watch youth football and the assembled group retired to the meeting room of the Best Western Shadow Inn for a triage session. The purpose was to inspect the airplanes and look for problems that needed to be fixed, and then fix them. This tends to hold down the carnage and a lot of problems can be resolved just by inspection.
Surprisingly, several airplanes failed the very first test - hold the leadouts together, and then try to wiggle the flaps up and down. The first airplane we tried had about 3/4" of up and down flap with no leadout movement. This led to some surgery, at which point we found that the flap horn was unbushed and worn out. We were preparing to repair it with a new bushing but then I held the pushrod and moved the leadouts, which showed the bellcrank pushrod hole was also worn out. We could have fixed the flap but the bellcrank would have required cutting out the spar, at which point we waved the white flag. A contributing factor was that the pushrod (3/32 music wire) had a bend in it. This makes it wear out sooner, and with more drastic effects, because in addition to just slop in the direction of the holes wearing out, the entire pushrod can rotate around its axis, and that gives free play with only a little wear. Fortunately, the pilot had another airplane to fly.
The other airplane that failed this test was a flapped, 40-60-sized airplane. It had a bit of slop, but what was alarming is that the pilot indicated that the airplane had ball links everywhere. This should result in *no* slop and if there is, something is very wrong. Sure enough, we took it outside into the blazing sun and looked down the leadout slot at the bellcrank pivot. I was looking for bellcrank tilt, but the screw holding the ball link was loose, and tilting as we moved the controls. So, more surgery, this time to get a nut driver and ball driver on the screw to tighten it through as small a hole as possible to preserve the integrity of the wing. And then JB-Kwick on the nut to hold it. We got in there with no real problem, but when we tightened it up, the controls became very draggy, completely unacceptable, and there was still slop. After some puzzlement, we realized that the ball link itself was bound up, verified by loosening the screw just a bit, free again. This must have loosened the screw. This test also indicated that the ball link at the flap horn was also loose. Major surgery this time, and sure enough, that screw was loose, too, but the ball link was OK, more or less. The *very temporary* resolution was to tighten the screw at the flap horn and staking it with JB Kwik, then backing off the ball at the bellcrank just enough to permit the ball to move on the screw, then staking that. This would be acceptable for a few flights. This pilot also had another (pretty good) backup airplane.
Most of the other airplanes were fine as they were, with only small fixes and adjustments required, mostly, making things secure enough to stay together and give consistent trim. Also, we checked the CGs and leadouts, things like that, with minor changes here or there. We also checked for flap tweaks and fixed as necessary.
We then retired for the evening. Ted, Jim, our WDA hosts Doug and Christy Barton, and I went to Woodland's famous hamburger shack, after Ted and Jim had a spirited, and spirit-fueled, political discussion.
Next day we hit the field early, and had good but hot conditions. David and I took turns flying on Circle 1, and with circle 2 unflyable due to some upgrades in progress, we reserved Circle 3 for coaching by Ted, once the test-flying was done. It quickly reached about 104 by about 10:30 in the morning, but then started dropping, and went down to about 95 for the rest of the day, which by comparison was quite pleasant.
I won't do a blow-by-blow of every flight, but we flew the ones we thought were going to be pretty good first, so that they could be sent over to coaching while we worked on the others. For some reason, we didn't have many flights over for coaching. I was a little disappointed that there were so few flights and only a few people taking advantage of the opportunity for coaching from one of the legends of the sport, and in particular, who managed to mentor both David and I to NATs wins, but I suppose this is why people get into ruts.
The general observation I had was surprising - almost every airplane, including relatively small ones, pulled as hard or harder as mine/David/Ted airplanes usually do. But more surprising, and very unlike the situation 20-25 years ago, almost everyone's control sensitivity was VASTLY slower with more loading than typical competitive airplanes. Used to be, everyone set up their controls way too fast and then tried to fix it with noseweight. Now they are generally much too slow with much too heavy controls for competitive flying.
This is critically important, because just like the example from the previous event:
https://stunthanger.com/smf/open-forum/trimming-your-model-for-flight-characteristics-or-personal-style/msg492698/#msg492698 where the airplane was simply too slow on the controls for me to even fly through a regulation-sized round loop, much less competitive corners. I would add that Dennis' airplane was VASTLY better this time and was one of the more pleasant airplanes to fly at the event, with very reasonable line tension and control loads, after some time to work on it since then. Note that this just gets him to *the starting point* for being able to progress to better flights through coaching.
The effect of the slow controls we found in most of the airplane/handle systems was to make it impossible to fly patterns without large arm/elbow motion, which should *never* be used when not absolutely necessary. When we got one airplane sped up the slow end of acceptable, the pilot flew it as he had before and GROSSLY overcontrolled it almost everywhere, because he was so used to putting in large elbow and arm motion that he was unable to adjust to it. The controls on this airplane were still quite slow, just barely fast enough for David and I to maintain good posture in ideal conditions.
This is the sort of thing that people don't really get and may be impossible to overcome unless they have outside help to give some objective evaluation.
But overall, both David and I spent most of the day removing nose weight or speeding up controls, and taking out excessive tip weight. We flew A LOT of flights, but with sufficient hydration (in my case, an absolutely remarkable amount of orange Gatorade, water, and diet Coke - all apparently exuded through the skin instead of the more conventional path) I was fine even at the end at about 3:00 when we wound down.
Ted ended up watching us from the side a lot and he said he could watch from beneath the awning and predict the changes accurately, and see the progress from flight to flight easily. Tells you how tuned-in you get after doing this in *7 different decades*.
We only ended up with two unresolved systems, one from the infamous OS46SF "right angle fitting" on a 46VF leaking, and the aforementioned worn-out flap controls. Even the "stuck ball link" airplane flew, with greatly reduced slop.
Anyway, all kudos to Jim "Uncle Jimby" Aron for arranging such a useful event (at his own expense, I might add).
As mentioned before, this is more or less like a slightly-more-organized regular flying session for us, we do stuff like this at our regular flying sessions for each other. IF someone wants to do the communication part, arrange for a few people to get together at Woodland or Napa every so often, please do go ahead, and let me know, and I would be willing to do this on a regular basis if I am available.
Of course, if others want to chime in with their observations, please do.
Brett
p.s. since the event, the airplane with the stuck ball links has had them all replaced, with different links, and is getting refinished.
Topic: Chumley Memorial Stunt Clinic (Read 1280 times)