Inside Hard corners are killing me!! UPDATE

[Paul Taylor]

I have a new Pathfinder and I’m really trying to like this plane. But when I try and do inside squares or triangles the plane seems to turn too much and my vertical climb goes way right. I then try and barely turn it and it’s not enough. I thought maybe when I built it I put the pushrod in the wrong hole in the bellcrank but my snake camera confirms I’m in the right place. I have about 3/4 in throw on the elevator. CG seems about right with the battery onboard. Might be a little tail heavy but seems ok. Outside squares are ok. Inside and outside rounds are ok. It’s seems to be only inside squares and triangles. Handle spacing is 4 inches on a Kaz handle.

[Paul Taylor]

[Paul Taylor]

[Paul Taylor]

[Dave_Trible]

I'm not too familiar with your handle Paul but it looks to me like the individual line spacing/location is adjustable on each line.   (That's a good thing).  It also appears that the 'up' line is set out further from the handle centerline than the 'down' line is.   That could give you the exact response you are describing.   Your airplane also has the stab mounted higher than the wing centerline I believe like many/most stunt airplanes.  This will also favor a bit faster inside turn than outside due in part to the wing and flaps blanketing the stab some when the controls are applied in the down position.   I'd try moving the top or up line in closer or as close as you can to the centerline to slow down the input that direction.   You could also move the down line out or downward to speed that one up to match then tame the whole airplane a little with some noseweight.

Dave

[Brett Buck]

I have a new Pathfinder and I’m really trying to like this plane. But when I try and do inside squares or triangles the plane seems to turn too much and my vertical climb goes way right. I then try and barely turn it and it’s not enough. I thought maybe when I built it I put the pushrod in the wrong hole in the bellcrank but my snake camera confirms I’m in the right place. I have about 3/4 in throw on the elevator. CG seems about right with the battery onboard. Might be a little tail heavy but seems ok. Outside squares are ok. Inside and outside rounds are ok. It’s seems to be only inside squares and triangles. Handle spacing is 4 inches on a Kaz handle.

   Just an observation - the handle seems to have a significant offset in the throw, more throw and lower pressure for insides than outsides. From the top finger rest to the "up" cable is about 5/8", and bottom finger rest to the "down" cable is more like 1/4"-3/8". That is a massive offset that will require you to hold "down" pressure all the time, and would turn pretty tight inside if you just relaxed your hand. The line tension automatically gives it "up". I would expect that to make it very tricky to do insides, you would have to keep holding "down" pressure, just less, to get a shallow inside turn.

      And while we would have to see the rest of the system including the lines and airplane all put together, your "up" cable is drastically shorter, maybe 3/4". Are you sure you are setting your neutral to perpendicular to the lines, or do you have forward/"relaxed" neutral?

    A third thought - when you hold you leadouts even with each other, do you have up or down?
   
      Brett

[Ken Culbertson]

My 2 cents says it is most likely your handle.  The main reason an experienced flier cannot stop a turn is that the plane is turning faster than your wrist/fingers can stop it. That is almost always the handle.  Most planes with the standard wing/stab/power lines relative to the wing centerline will turn better outside for reasons already mentioned but the one that is critical is the wrist position.  Brett covered that but let me add how I find the center.  If your wrist is straight and your fingers wrapped as if holding a handle the center is approximately the bottom of the knuckle on your middle finger.  That is the center for your spacing.  Yours is too high.  My guess a quarter to a half inch.

I may be off base here but that range of control is way too little for my tastes. I have about double that or more.  Don't use it all but it is there.  To do a respectable pattern with that little control you would need a CG that would make Gieseke blush.  I have only flown one electric Pathfinder.  It was slightly nose heavy by IC standards. It cornered and locked beautifully.  You might just be a tad tail heavy.

Ken

[Perry Rose]

I have a Pathfinder also and control throws are 1 inch up and down flaps and elevator. No problems with over turning. Did you make the flap horn shown on the  plans?  Mine balances 3/8 inch aft of the plans spot. I had to ad a 2 ounce heavy hub and a Fox .35 muffler to the LA .46 to make the turn rate more controllable. Line spacing at the handle is 3 3/4. You didn't show the stab leading edge, does it have a nice smooth radius? Are the flaps and elevators at zero in neutral and are they in line with the wing/stab chord lines?

[Ken Culbertson]

I was able to watch you in the video session last night, and I think you got the right advise.  My only comment is that to me anyway, the center is not the center of the grip, it is the center of your wrist in normal level flight.  Feel free to move the set up and down until you find it.  I finger fly with a hardpoint handle so that setting is everything to me and being off even a 1/16" will show up in the difference in locking insides vs outsides.  In my case the center is about 1/8" below the center of the grip. Good luck, the Pathfinder is a great airplane.

Ken

[Perry Rose]

I have found that on planes with 3/8 or 1/2 inch thick flat stabs, like the Pathfinder, rounding the stab leading edge will cause hunting. I had one Pathfinder that I pointed the stab leading edge to 1/16 radius just on the balsa 1/2 inch sq. frame and not into the ribs. Then I built the one I have now and rounded the stab leading edge and it wallowed all over the place. I took pieces of .080 nylon? rod and glued them on the stab leading edge and the hunting disappeared. I used a Geezer ( AARP) card to make a centering tool and taped then glued the rod to the leading edge.

[Brett Buck]

I have found that on planes with 3/8 or 1/2 inch thick flat stabs, like the Pathfinder, rounding the stab leading edge will cause hunting. I had one Pathfinder that I pointed the stab leading edge to 1/16 radius just on the balsa 1/2 inch sq. frame and not into the ribs. Then I built the one I have now and rounded the stab leading edge and it wallowed all over the place. I took pieces of .080 nylon? rod and glued them on the stab leading edge and the hunting disappeared. I used a Geezer ( AARP) card to make a centering tool and taped then glued the rod to the leading edge.

     That is perfectly consistent with our experience with flat stabs from the 90's, with similar solutions. Interestingly, the tracking issues do not happen all the time, just sometimes. The various flat-tail Imitation XL/Infinity worked OK without any enhancements, apparently the same with the Impacts. The flat-stab Trivial Pursuits needed a something (actually several things) around the LE to reliably track.

     Try taping wire top/bottom right where the LE radius ends and the flat begins, too, that made a huge difference on the airplanes that had flat-stab problems.

    David Fitzgerald's De-Tails article covered these experiments in detail.

        Brett

     

[Brett Buck]

     As above - center the leadouts on your hand and make sure that neutral is perpendicular to the lines. Then, if the airplane turns different inside and outside, adjust *the airplane* until it responds correctly.

    I occasionally use very small amounts of centering and neutral adjustments - but only as workarounds to fixing the airplane, or tiny adjustments as something changes during a day.  By tiny, I mean  5-10-20 thousandth of neutral adjustment and at most 1/16" of centering (and then only because I can't move both lines half a hole).

     These extreme maladjustments from your picture - like the nearly 1/2" center offset and what appears to be an astronomcally large neutral offset - may or may not be the source of your problem, but it is at the very least a symptom of some other maladjustment or misalignment somewhere else. If you incessantly practice in constant conditions, you can learn to fly this way reasonably successfully, but at best it is teaching you bad habits and I guarantee if you stop incessantly practicing for a few weeks, you will be back to square one and starting over.

     Brett

[Paul Taylor]

Ok was on the Hangouts last night and Rick said the same thing about my handle. I have corrected the handle and I have 4 1/4 in spacing.
I will start there and report back after Saturday’s session.

Thanks a bunch guys!!

Much appreciated. 😎

[Paul Taylor]

Just wanted to update this thread.

I’m back to liking the plane.

The handle was the problem.
Now if we can fix the guy holding the handle. 🤣

Thanks Brett, Rick and all the great folks of Stunthangar that participated in the fix. 🙃

[Dan McEntee]

Just wanted to update this thread.

I’m back to liking the plane.

The handle was the problem.
Now if we can fix the guy holding the handle. 🤣

Thanks Brett, Rick and all the great folks of Stunthangar that participated in the fix. 🙃

   I learned a long time ago that problems are usually related to the nut on the handle!!
   Have fun!
   Dan Mcentee

[Brett Buck]

The handle was the problem.
Now if we can fix the guy holding the handle. 🤣

Thanks Brett, Rick and all the great folks of Stunthangar that participated in the fix. 🙃

     You are quite welcome! Glad it worked out for you.

      This case is a really good example of how you can overlook the most basic issues. This sort of thing is what we mean when we talk about "attention to detail", it's really simple stuff that causes most of the problems .
 
     This is why having local expert help at hand is so important. While I and many others here are glad to try and diagnose things over the internet, someone actually present at the time could just glance at it and see the issue immediately.

    By the way, you mentioned a Kaz handle - but that doesn't look like any Kaz handle I have seen. What does the other side look like? It seems like it has some sort of nylon/delrin slider to carry the lines.

       Brett

[Paul Taylor]

     You are quite welcome! Glad it worked out for you.

      This case is a really good example of how you can overlook the most basic issues. This sort of thing is what we mean when we talk about "attention to detail", it's really simple stuff that causes most of the problems .
 
     This is why having local expert help at hand is so important. While I and many others here are glad to try and diagnose things over the internet, someone actually present at the time could just glance at it and see the issue immediately.

    By the way, you mentioned a Kaz handle - but that doesn't look like any Kaz handle I have seen. What does the other side look like? It seems like it has some sort of nylon/delrin slider to carry the lines.

       Brett

It’s one I made. I have one I copied. I also made one as a gift to Sparky.