Hunting oh so slightly in inverted

[Tim Wescott]

So, I have this plane that someone gave me.  It's old and beat up (they doped a plain paper sticker on it that says "FAI" and some other stuff, if you can imagine that), but it flies pretty good.

It hunts, oh so slightly, only while inverted.  It flies very nicely upright.

I'm not 100% sure that it's the plane, but I've done pretty well at this task on other planes that aren't nearly as good all-around.

Anyone have suggestions for things to consider to find the problem?

[Dan McEntee]

  It's you. If it hunts inverted it will probably hunt upright. Are you holding your hand flat?  If you don't turn exactly the same as the model that will induce the hunt.
  Type at you later,
  Dan McEntee

[Dane Martin]

Fly it inverted with your non dominant hand. That'll tell you if it's you or the plane.
Of course if it hunts worse, you may just be awful at flying with the other hand, thereby rendering this experiment useless.

[Paul Walker]

Try 1/2 turn up elevator.

[BYU]

Try 1/2 turn up elevator.

Jeepers! like you would know anything about this plane.

[Dennis Toth]

Tim,
You didn't mention what ship or what type of leadouts were installed. I would suggest that you clean the leadout wires and flying lines. Next check that the leadouts are set in the correct position for you flying speed. Most hunting is caused by the control system binding someplace.

Best,   DennisT

[Alan Resinger]

I would strongly suggest following the directions on the plans and add a half turn of up elevator. Most times the planes designer knows best.😁😁😁😁😁

[Doug Moon]

If you trim out that hunt the plane might not fly as well.  One of my best planes hunted very slightly inverted.  I just learned to deal with it.  When I would change the elevator to fix it the rest would go down the drain.  Note: later, a couple of years, after the elevator horn got some slop in it that hunt got better.  Then later after that, 10 years, the fuse nose delaminated in flight and the wing folded and I lost my very best most favorite prop.

If you change it be sure to remember what you did so you can put it back. 

[Tim Wescott]

Tim,
You didn't mention what ship or what type of leadouts were installed.

I was assured by the guy who gave it to me that it's essentially an Impact.  It's got plug-in leadouts.

I would suggest that you clean the leadout wires and flying lines. Next check that the leadouts are set in the correct position for you flying speed. Most hunting is caused by the control system binding someplace.

I clean the flying lines before each flight, but have been neglecting the leadouts.  I'll correct that oversight.

I'll certainly double-check for binding.  The last time I checked the control system felt nice and free, but problems may have developed.

The ship bears obvious signs that the previous owner cut into it to check the control system, but at least on the ground the controls feel just fine.

[Ken Culbertson]

There is only one place in the pattern where inverted hunting is a real problem and I side with Doug on that one having tried unsuccessfully to trim it out without destroying level flight trim.  The hunting I get is not the bumpy kind that you get with sticky controls but he gradual kind like someone is pushing the whole plane up or down.  In my case it is usually down.  9 times out of 10 when I see the plane starting down I will find my hand is in the wrong position.  If I am in the 1st two laps I will correct the hand position, if not I will live with it and since switching to electric I have had to revise how loudly I comment on it when it starts

Another thing I have noticed is that when I am having hunting issues I find that others I am flying with are having similar problems.  Are you sure that your hunting is not weather or terrain induced?  We are all familiar with the ground effect that makes that last couple of inches on landing so much fun.  An uneven flying site can easily create a layer of unstable air near the ground that makes you think that the plane is hunting.

Or, you could just buy a hunting license and make it legal.

Ken

[Larry Fernandez]

Just a little something to think about.
A few years back, I had a Thunderbird that had a hunting problem that was getting the best of me. I tried everything. Played with the CG, tweeked the elevator and lead outs.
It was suggested by one of the local hot shots, to add in a touch of down thrust.
When the big shots speak, I listen.
So I simply added washers under the front mounting lugs, then lo and behold, no more hunting.
Like I said, something to think about.

Larry, Buttafucco Stunt Team

[Doug Moon]

Just a little something to think about.
A few years back, I had a Thunderbird that had a hunting problem that was getting the best of me. I tried everything. Played with the CG, tweeked the elevator and lead outs.
It was suggested by one of the local hot shots, to add in a touch of down thrust.
When the big shots speak, I listen.
So I simply added washers under the front mounting lugs, then lo and behold, no more hunting.
Like I said, something to think about.

Larry, Buttafucco Stunt Team

THIS!!!!!

[Tim Wescott]

Another thing I have noticed is that when I am having hunting issues I find that others I am flying with are having similar problems.  Are you sure that your hunting is not weather or terrain induced?  We are all familiar with the ground effect that makes that last couple of inches on landing so much fun.  An uneven flying site can easily create a layer of unstable air near the ground that makes you think that the plane is hunting.

It's a nice flat paved circle, and the airplane was dead steady in upright level flight, and for at least the first half hour of my practice session on Wednesday the air was dead calm.  I'm not going to rule out pilot error, but it sure seems that conditions are perfect for it.

[Jim Carter]

Now I am by no means as qualified as so many others on this site but why not have someone else of your caliber, give it a flight or two and see if they sense the same flight characteristics?  That would certainly eliminate your style as the problem then the modifications could be made in earnest. 

[Larry Fernandez]

THIS!!!!!

When the the “Hot Shots “ speak, we should listen.
Mr Moon is one of those “Hot Shots”

Larry, Buttafucco Stunt Team

[FLOYD CARTER]

To verify if engine thrust is the culprit, fly inverted until the engine quits.  Then, observe whether or not the glide seems to "hunt".

[TDM]

I have a question. If a plane track nicely in normal flight and hunts in upside down could it be simply because the neutral position of the handle is not set properly? We are very used to fly normal flight level and we do not notice the bias on the handle in normal flight but when we go inverted and try that same neutral point (kind of because there is a tine bit of correction between upright and inverted) we actually give the model some extra up or down in order to fly level, the muscle memory takes over and creeps in and imputes and unconscious control, we realize the model goes up or down and correct again and the cycle continues as we constantly correct for that giving an impression of hunting inverted when in reality the handle is off. In this case scenario the question becomes how to properly set a neutral point on the handle.

[Tim Wescott]

Now I am by no means as qualified as so many others on this site but why not have someone else of your caliber, give it a flight or two and see if they sense the same flight characteristics?  That would certainly eliminate your style as the problem then the modifications could be made in earnest. 

I'll see who I can sweet-talk at the next contest.  Unfortunately, with my schedule I end up practicing on Wednesday mornings from 7:30 to 9:30 or 10:00, alone.  Occasionally Fridays or Saturdays, but those are mostly taken up with honey-dos.  Maybe Fred Underwood would be willing to fly with me at Salem sometime, if he could stand getting slimed.

[Tim Wescott]

Now I am by no means as qualified as so many others on this site but why not have someone else of your caliber, give it a flight or two and see if they sense the same flight characteristics?  That would certainly eliminate your style as the problem then the modifications could be made in earnest. 

So, caliber is how well you fly, does that mean that the guys who fly better than I do are bigger bores?

[Fred Underwood]

Tim, PM sent.  I can clean my hands after slime.

[Steve Helmick]

My contribution will be to repeat three ideas already posted. Honestly, my first thought was to add downthrust, second was to adjust handle neutral, and third was to do anything that Paul says to do. Probably would start with anything Paul suggests.    Steve

[Mike Haverly]

Option three.

[Joe Yau]

  It's you. If it hunts inverted

Best way to isolate that thought is to check against another plane that you know it doesn't hunt..