[Courtesy of Brian Reed breedatrad "at" yahoo.com, March 1999]
It was a beautiful day today here in PA. The sun was shining and not a cloud in the sky! Sure, it was kinda' breezy (And only about 40°F), but that just means you fly half a tank, warm up your fingers in the car for a minute while the Heli's idling, and then fly the rest of the tank. And, before you start to cringe at the rosy beginning to my little story; stop worrying This is one lesson I didn't have to learn, "The HARD way"! Mostly, I'm passing this little lesson on so that others who have to learn on their own might benefit from my mistakes.
I've recently moved up to 30% fuel and a couple of small, on-going problems have started to get worse! The tail didn't feel "solid"(Arcamax PiPro) and seemed to always be wandering slightly whether hovering or doing maneuvers. There was a slight buzzing in the horizontal fin that I couldn't balance out and I kept burning through muffler couplings every five or six flights. My hovering wasn't as smooth as I'd have liked it to be either; Especially the collective (Always bouncing up and down like I was over-controlling). The Heli just didn't "feel" right. It was getting pretty irritating!
A few weeks ago I purchased a copy of the Pöting Cup video and've been watching it a couple of times a week for inspiration while it snowed outside. Something I started to notice was the AMOUNT of exhaust flowing from their mufflers. Way more than I had! My engine sounded real smooth in the hover, but I was used to listening to props on planks and I had it tweaked up pretty good.
Not knowing what else to try at this point, I decided to go back to the factory needle settings and try it again. This time I wouldn't touch the mid-range needle at all and I'd fly it around for a few minutes after each adjustment paying close attention to any changes. Talk about smoke! It was definitely too rich at this point (Two full turns open) so I closed it a quarter turn. Better, but still a little sloppier than I wanted.
At a turn-and-a-quarter things really started happening but the engine was pulsing in and out of a lean two-stroke and slowly "wagging" the tail (Smoke was also getting pretty thin). At one full turn it was really singing and the exhaust was almost gone. It sounded very powerful (Like a plank all leaned up on the ground) but the test hops between adjustments indicated that I was too lean. I finally settled on 1 1/2 turns (3/8 of a turn richer than where I had been flying previously) as a fair compromise between good smoke and smooth sound. And guess what?
My tail doesn't wander now and the buzzing's gone from my horizontal fin! The tail stays PUT during maneuvers (That's a Hitec 525 on my T/R too, Don A.). Collective control is MUCH improved in the hover since the engine's no longer pulsing in and out of a lean two-cycle making the heli jump up and down with each small change at the stick. It just plain "feels" better.
What a discovery! And you experts reading this probably had it all figured out at the beginning, but as an experienced (21 years) plank flyer, I thought I was doing the right thing. Something else I discovered was that I was too tense, sometimes leaning forward on the balls of my feet or putting all my weight on one foot or the other. Reminding myself to stand squarely on both feet and to relax has also done quite a bit for my hovering Especially in windy conditions.
Well, there it is. My latest epiphany! Now maybe I can start working on more of that stuff I've been practicing on the Sim. Oh yeah, speaking of that: Some of you might remember a post I made a while back about how much better my CSM Sim flies with the 9ZHP Tx as opposed to the Super-7 I'd been using. In addition to these, I've also been using an 8UHP and, with it's separate, five-point REVO Curves, it feels almost as solid as the 9ZHP. The 8UHP's trims have to be turned down to an increment of "2" to get it to trim for a perfectly still hover, but it's WAY better than the 7-channel. Thanks for listening.
Brian (Concept 60SRII, OSWC, Arcamax PiPro, 9ZHP) Reed