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Balanced turning questions

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Matt Brown:
I posted on facebook about my maiden flights on my new Pathfinder LE from RSM. While going through the early flights getting a feel for it, I felt like it turned much better inside than outside. Several guys on facebook suggested shortening the elevator pushrod. This makes some sense to me and is on my list of things to consider. I wanted to analyze things further before cutting into my plane. I didn’t have room for a hatch back at the elevator so I just covered the area with a silkspan patch. I don’t want to cut it out until I’m sure that’s what it needs as I have to go through the refinishing process afterwards.
I set my controls up best I could during the build. I locked the bellcrank to neutral and played with pushrod lengths to get throws as equal as possible. After the maiden, I went back and took some basic measurements again. When I pull the up line, I get 1-5/8” up elevator travel and 1” of down flap. Conversely pulling the down line such that I get the same 1-5/8” down elevator travel I also get 1” of flap up travel.  The 1-5/8” of up travel is max up throw. However I do get a bit more down elevator throw at the mechanical limit. I get 1-7/8” of down with about 1-1/4” of up flap. To me, this seems like it should turn outside better but it definitely doesn’t feel like it to me. It feels like it’s mushing through outside sharp corners whereas it really pops through insides.
Can someone help me understand what may be happening?

Pathfinder LE
Ro-Jett .67 on header muffler
13-1/8 x 4.5 3 blade carbon prop turning 8600
63.5 oz
64’ Spectra lines
5.6-5.7 lap times right after takeoff
No wrist bias in the handle
I did try to adjust throw bias in the handle but plane still felt mushy in outsides

Thanks, Matt

Paul Wescott:
I think you’re going to have to cut into the tail and move the horizontal stabilizer down so it’s directly in line with the wing.  Otherwise turbulence from the flaps will affect the stab/elevator differently during up/down control input or inside/outside maneuvers.  Or so I’ve heard.

Ken Culbertson:
I think you have done the "due diligence" on the controls.  I seriously doubt you are reaching the stops on the controls so the extra on one side is not that important.  I have only flown one Pathfnder and it was well balanced by the owner so that is no help.  Before changing the pushrod, which you may need to do anyway as a final trim (I can't think of a plane I have not had to do it on) check the thrust line.  Do you have any down thrust?  It is not uncommon to need a little.  I know this sounds silly but can you quantify "better".  Do you mean tighter, faster or tracking?  My planes all fly equally inside and outside on the first two once trimmed but for some reason I get better tracking outside.  I think that is due to what Paul Described.   My next one is an inline twin so that may change!

Ken

Dan McEntee:
  Make sure there is nothing flexing in the controls. No pushrod flex and no slop in the pushrod connections to the horns. Borrow some Robart incidence meters and put one on the wing, power plant and stabilizer. The wing should be set at zero, and then see what the other two read. I follow the Bob Whitely set up as listed in "Things That Always Work" that was in an article he wrote for Stunt News years ago. Basically it's wing set at 0 with flaps neutral, power plant has at least one degree down and one degree right thrust, and stabilizer had 1 to 2 degrees positive incidence.. I have been setting up my models this way ever since I saw the article when it came out and have never had issues with hunting and models always groove well. I can usually do the pattern on the first flight if I have a known good engine/tank combination installed. Any differences in inside and outside turns were simple line spacing adjustments. Also, do you seal the hinge lines on wing flaps and elevators?  If not, seal those with tape. Numerous threads on that on the forum. Make any changes one at a time and fly several flights to evaluate them. If you are doing the pattern you should not need much. Your lap times might need to be picked up a bit. If 5.6 and 5.7 are accurate, it may just be too slow for that airplane. Shoot for 5.4 to 5.5 and see how it feels. A few tenths can make a big difference. Line sweep also could be looked at.
  Type at you later,
  Dan McEntee

Matt Brown:
As best I can measure, everything is 0-0-0. My Robart incidence meters both want to stick a bit on that last half degree or so. Usually lightly tapping the meter will settle it halfway close. The plane flies very well though both inside and outside loops, tracking very good. It’s the square corners and sharp exits of maneuvers that really stand out. Insides really turn very tight and crisp. Outsides just kind of mush through. Second corner of the hourglass seems fine but the outside exit of the first half of the wingover on the very first flight just mushed as did subsequent wingovers. The next corner of the wingover(from inverted to vertical) didn’t seem too bad though.
I may try some down thrust next time out. May also go ahead and cut into it and adjust the pushrod. Weather doesn’t look promising anytime soon though.
There is also the possibility that it is purely a perspective issue on my part. I’ve had several SV11 ARFs, both electric and glow. They all seem to turn better insides than outsides.

Matt

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