The few times I went to the AMA Nationals, RC Scale was a big attraction. Incredibly detailed models. Years of work. A surprisingly high percentage had never been flown. Thus the most entertaining of crashes.
Easily the most stunning examples of not changing stuff in order to gain a better flying model.
Do we see something similar in CL Stunt? I think so.
Is there available a new tool for use in changing stuff, evaluating the results? Yep. The still kinda new ARFs, now available in a wide variety.
The basic premise here is that your CL Stunt model is merely a tool. A tool which can relatively easily be adjusted. We call it "trimming" the model, but "adjusting" it or even "changing stuff" are useful terms.
While it might be too obvious to state, just like the RC Scale guys who were (are?) so apprehensive about the health of their masterpiece they wouldn't even fly the thing prior to the Nationals, I continue to see CL Stunt models which beg to be tweaked. But are not as there is an understandable fear of getting the leadouts too far forward, removing too much tip weight and so on.
I was reminded of this conflicting situation while coaching new retread and long-time friend Rick Cochrun. During a whole series of flying sessions Rick would see me changing stuff on my models. And sometimes snort in derision at the level of detail being employed, when in actual fact some of the changes were significant.
Truth be known, I have not always been such a fan of changing stuff. From the very first I had the advantage of flying models predetermined by Don McClave to be good 'uns, powering, muffling, propping and fueling them as he suggested and then depending upon a couple "laying on of hands" processes from Don in getting them "trimmed."
The models ended up being pretty fair, but not through my own initiative, at least not at the detail level. Thus I didn't learn a lot which could be readily transferred to next-step models.
This ended with a sudden rush when I first got my hands on engines which really haul the mail (O.S. 20FPs with the Brett Buck Tune-Up), a series of ARF Flite Streaks, two or three SIG Skyray 35s.
With motive power handled in a superior fashion I began to adjust/trim the models with abandon. During some flying sessions I would change stuff almost willy-nilly, just to see what happened.
Now I see the same thing taking place with Rick. Not incidentally with an ARF, in his case this being a Top Flite Tutor II with a box-stock O.S. 40LA for power.
Prior to the McMinnville, Oregon, contest I couldn't even convince him to level the wings with a relatively minor flap tweak. He didn't want to risk the best-flying model in an admittedly small fleet of kit- and plans-built models.
Ah, but Rick had some success in McMinnville, scoring in the low 400s. Having flown his Oriental/25FP in Classic Stunt, the Tutor II in P.40 Sportsman, by the time for PA on Sunday, still using the ARF, he actually did tweak the flaps. Uh, between rounds, where previously resisting doing so in practice sessions!
I found it to be mildly humiliating that it took the urging of Don McClave to actually begin this process where I had been rebuffed numerous times. On the other hand, Mr. Rush and I have a similar story to tell concerning unsolicited input from Da Dirt and Howard to none other than PW. Yep, only after Don told Paul his World Champs-bound model was very slightly tip-low in inverted flight did we see the appropriate fix put into play. Sigh...
Back to the scenario at hand, last night I spoke with Rick. He has been flying almost every day. And is changing stuff. Sometimes with purpose, sometimes just to see what happens. Not a small factor, he has two more Tutor II ARFs on order.
Rick went on to relate that he is changing stuff almost as readily as I now do with my Impact. I think that a bit of a stretch, but it could actually be true.
More significantly, Rick is really pleased with the results. For example, no longer is that roll-in/roll-out deal in the 8s, the changes in line tension, something which needs to be dealt with at the handle while flying. Golly shucks the model can be adjusted to eliminate this nonsense...
Get an ARF or two. Power them appropriately. Don't go off the res here as good engine runs are important in getting consistent feedback during the trimming process.
While it seems standard practice to time level-flight laps upright and inverted to get lap times correct, this is only the beginning. What you really want is the same model speed throughout the maneuvers, and getting level-flight speeds equalized frequently falls short.
With the tank adjusted to the point where the engine won't go seriously lean or rich, instead of fixating on level flight, tune tank height by flying horizontal 8s. You want the same model speed through both the insides and the outsides, to heck with any differences in inverted and upright level flight.
Same thing with getting the wings level. While there may be a few eagle-eyes out there, I personally have not seen anyone get the wings perfectly level while viewing the action from the center of the circle.
Yes, a good look by a friend from outside the circle will sometimes help. But not always, either due to a lack of competence on the part of the helper or reluctance on your part to accept his observations. See above for an example of the latter...
What does work is to again do a series of horizontal 8s. Watch the model. Pay close attention to line tension. Don't let a big hit of tip weight confuse you; there will still be strong indications from the model as to what it likes when it comes to actually getting the wings perfectly level.
In order to ease the trimming process, build or retro-fit your models such that all adjustments are easy to make. That fancy-schmantzy closure on your tip-weight box might be kewl, it may have taken days to engineer and fabricate. But it is totally worthless if not easy to use, the hassle of merely opening it up keeping you from making changes, sometimes minute changes to the positive or the negative being based upon nothing more than a whim.
I sometimes get grief for an open bay on the tips of my ARFs, for example. Yeah, it is kinda unsightly in our world, but I can change tip weight in a flash. And frequently do so as a result.
Same thing with the hardware for leadout location. Lots of choices here, but it is best to have the leadouts able to be moved readily, accurately and with a fair bit of repeatability.
Another tip is nearly free. I have taken to closely watching the models of fellow flyers during practice sessions or at contests. The premise: "If that were my model, what changes would I make?" Yes, it is an exercise in first identifying faults, but also in formulating remedies for same.
What you do with this information is up to you, noting that walking up and down the flight line handing out critique sheets might label you as an interfering know-it-all, this in a crowd of K-I-A types, but it is still an interesting exercise. One with the benefit of learning the most interesting of things concerning a wide range of trim options.
So don't feel guilty about refusing to take too many risks with that plans-built Stunt model in which you have months of effort. Pick up an ARF**, they are really quite cheap, to the point of being disposable.
Fit it with good controls, add adjustable doo-dads as you see fit...
And start changing stuff.
Dan
**If that ARF you pick up is the Tutor II, at least with Rick's
model the stock leadout guides will not allow moving the leadouts forward
to a point approximately 3/4" to 1" to the rear of your chosen
balance point. Check out this feature; it is an important tool in getting
your model dialed. And Rick's example had a huge chunk of steel for
tip weight, easily way too much for his model.
This page was updated Sept. 1, 2006