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Erratic elevator control...please help

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Erratic elevator control...please help

Old 12-07-2015, 11:25 PM
  #26  
zemanski99
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Thanks for the input. I can assure you that the battery does not move during the flight so as you said it should not be CG problem. I am the only one in the club, who is running the JR XG14 transmitter, rest of the guy are either Spectrum or Futaba and none of them have the same problem as me. I thought it was my old XG7 transmitter which was the problem, but it still continue despite me updating the transmitter to XG14 which is brand new. So what are my options...change the whole system to Futaba? It will be expensive and there is no guarantee it will solve my problem...what do you think, best Jan
Old 12-08-2015, 04:55 AM
  #27  
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Ok, go ahead and balance level, hope that works out for you in 20 mph crosswinds on approach.
Still try and balance a bit nose heavy, and see how it goes, you can always change it,
Old 12-08-2015, 06:04 AM
  #28  
flyinwalenda
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It's interesting to read how some approach this issue. Some think like I do approaching it logically.
9 planes with the same issue over a period of time resulting in crashes.
CG issue ? Highly doubt it unless every plane had something heavy break inside falling back into the tail making it tail heavy resulting in erratic behavior . Nine different planes over a period of time ? What are the Vegas odds on that?
Mechanical issues with horns.clevis, geometry ,etc...? That could cause the issue but again, on 9 planes ....highly unlikely.
I still say it's a transmitter/receiver issue ;either an rf issue or a software or programming issue. Perhaps the OP has some mixes programmed on every model and he is inadvertently hitting a switch. Maybe there is some ancillary electronic device plugged in on every model causing intermittent issues(I've seen that before) .
Many single issues could contribute to this problem on a single plane or perhaps two, but nine? again, highly unlikely.
Old 12-08-2015, 06:11 AM
  #29  
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Anything can be the cause.but to always balance in the nuetral position has such a small margin for error .
Old 12-08-2015, 06:21 AM
  #30  
Jennifer Curtis
 
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There is a BIG difference between balancing
level at the neutral point and balancing level
forward of the neutral point. By balancing level
you know where the cg is, whether it is at
the neutral point or somewhere else.

Balancing level does NOT mean balancing
at the neutral point. It means balancing
so the fuselage is level. Wherever the
plane balances level, that is the CG. Once
you balance level you know where the CG
actually is and you know exactly how far from
the neutral point it actually is.


Jenny
Old 12-08-2015, 07:31 AM
  #31  
da Rock
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Originally Posted by zemanski99
This is the first time I heard that you balance with nose down angle. I have all my models balanced with fuse level. Could this be my problem then ??? best Jan
Level is the best way. It tells you where the CG really is.

Nose down... Tells you only one thing for sure. The CG is somewhere forward. How much is a guess. Why guess?

Balancing level is NOT your problem. In fact, if balance was your problem how have you gotten so many good flights and suddenly a bad one?
Old 12-08-2015, 07:35 AM
  #32  
suburban95
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OK I am no expert but while reading all these replies I did not see anyone mention what type of aircraft we are talking about ie: High wing or low wing, Fuel or electric. If they are fuel planes maybe the fuel tank location is the problem. Seems to me that this happens nearer the end of a flight and not at the beginning so maybe it is fuel level causing a CG shift? Also if high wing are you balancing right side up and low wing upside down? Just thought I would throw that out there.....
Old 12-08-2015, 07:53 AM
  #33  
ahicks
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Suburban95, I'm with you. No further comment from here until much more detail is known about the plane(s) we're talking about, and the more detail, the better.

This sure sounds like a dose of PIO (pilot induced oscillation) that can very likely be tamed. With multiple planes AND radios involved, our OP/builder is the only common denominator.....

Therefor a second request for more info on specifics and possibly some pics.

Last edited by ahicks; 12-08-2015 at 07:56 AM.
Old 12-08-2015, 12:52 PM
  #34  
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what kind of push rods do you use ?
I think your push rods might be flexing ,when the speed pushes the elevator back
Your push rods must be attached to the inside of the fuse ,and to each other , so they --cannot flex --in there middle , when in flight
The increase thrust of a gust of wind ,could be enough to over power the rods ability to stay ,straight ,from the servo to the elevator horn
Always check the elevator horn ,for wear -loose
Use Ca glue to make the horns base ,a hard place
Old 12-09-2015, 11:50 AM
  #35  
Rodney
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Since this happens late in a flight and then only after several good flights, the problem has to be in either the receiver or the transmitter; most probably the transmitter. What could cause such intermittent failure? Several things, the connection between the antenna and printed circuit board in the transmitter is loose or intermittent; or with extended use some component is heating up and becoming intermittent or failing while hot. For the receiver, a bad connection somewhere between the battery terminals and the receiver (bad switch, bare wires that contact under vibration, connector that occasionally opens under vibration, battery low and has to high an internal resistance). Whatever, the problem has to be in either the transmitter, receiver or wiring between the receiver and other components.
Old 12-09-2015, 05:40 PM
  #36  
ahicks
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2 different transmitters have been used, w/identical results.
Old 12-10-2015, 03:46 AM
  #37  
flyinwalenda
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No, not identical results.
The OP crashed nine planes over a period of time due to intermittent erratic control surface behavior . He then changed the transmitter to a new one and has been flying fine and just now had an incident with one plane(not nine) . I say this latest crash on the new tx is just coincidence and unrelated. Unless the op reused the same receivers,antennas, and other ancillary electronic devices.
After 37 posts we still don't know all of the details of what is in the planes.
Old 12-10-2015, 12:15 PM
  #38  
Lownverted
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Jan,

Sorry you are having issues, but I see a couple of clues here. I had a friend with a similar situation, and were were able trace it back to how he had set up his radio. He did not fully understand how to program his radio, and in his case , the flaperon and mix functions. He realized this and only flew with his switches a "certain way". When I got a hold of the radio the problem was obvious. When the flap switch was moved, he had unwanted surface movement. On top of that he had mixed the elevator to flap function so at some elevator deflections it would cause a gnarly roll or even a departure because it was on a multi point curve, so only was effected at partial non linear travels. This happened on multiple platforms because he copied the same "base" model for each new one. He just accepted these limitations as normal.

Could any of this apply to you? You said you are the only one who who flies JR. Have you checked for unwanted control interaction with the switches in all positions?

Red
Old 12-29-2015, 11:33 AM
  #39  
wcmorrison
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Other than individual control issues, jerky fingers and the like, it may be elevator servo's breaking down. They do have wear and tear on the inside with feed back loops (potentiometers). You can also have connector points beginning to have corrosion and you lose signals or voltage to the servo, that would be more of an intermittent kind of issue. Sometimes dielectric grease can prevent some of that kind of thing on connectors. Bear in mind the elevator is used a great deal more as a flight control compared to the other servo with perhaps the exception of the wing servo's. And if you are using two wing servo's, sometimes one can break down and you can still fly with problems at least long enough to land.

I know I had a rudder problem for a while and figured out it was dumb thumbs. Once diagnosed, I learned to compensate and sort of retrain my brain and that problem went away. Flutter could be an issue but somehow I do not think it would carry from aircraft to aircraft. I still go back to servo internals breaking down. That seems to be the weakest link.

Last edited by wcmorrison; 12-29-2015 at 11:36 AM. Reason: typos
Old 12-31-2015, 06:46 AM
  #40  
tony0707
 
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From my own experience ,my first planes i bult 20 years ago when starting in RC ,were balanced level as that was what i did flying control line for 5 years
My planes would not come down to the runway on final
You must have a --slight bit of nose down , built into the CG or the plane will just hang in the air ,when you need it to decend and touch down
Level makes the plane to floaty over the runway
Bin there done that !
Old 12-31-2015, 07:22 AM
  #41  
tony0707
 
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Do use the hole closest to the servo screw you can , as this allows the servo to keep its pot clean ,by increasing the full extent of the servos travel at the pot
That will give you a --better feel --on the sticks as the total travel is the same ,but the travel moves more slowly through the sticks curve
You may just be damaging the balsa that is located under the horn, after a given number of flights
The balsa is often crushed by the horn ,at installation
I pin hole the balsa under the horn ,use Ca ,and a piece of 1/16 ply on top and bottom of that and then install the horn
Slack that developes between the clevis pin and the horn ,has to be inspected at intervals
Any slack from the servo arm ,to the horn ,will increase itself ,all must be snug
Hayes clevis' s are my choice
Use the red sullivan rods ,with the metal pushrod for the most flex free ,direct connection possible
A fly on rails ,feel
They MUST be secured to the inside of the fuse ,about mid way thru the inside of the fiuse ,to prevent the red sleeve from flexing ,when the wind is pushing on the elevator
Only my best guess , as this is an odd thing to be happening to more than one airframe ,with a radio having been changed
Old 12-31-2015, 07:47 AM
  #42  
Top_Gunn
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Originally Posted by tony0707
From my own experience ,my first planes i bult 20 years ago when starting in RC ,were balanced level as that was what i did flying control line for 5 years
My planes would not come down to the runway on final
You must have a --slight bit of nose down , built into the CG or the plane will just hang in the air ,when you need it to decend and touch down
Level makes the plane to floaty over the runway
Bin there done that !

No. A plane must be level at the balance point (which most of us call the CG). That's what "balance point" means: It's the point where the plane balances level.If you "balance" it at some point with the nose somewhat down, that just means the balance point isn't where your fingertips (or whatever) are: it's somewhere forward of that and you don't know exactly where. There's got to be some point for any plane at which it will balance level. Do you seriously mean to deny this? If it weren't the case, you'd have to keep adding weight to the nose forever!
Old 12-31-2015, 11:09 AM
  #43  
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Originally Posted by zemanski99
..... it's happening to all of my models at least once in a while, is that during level flight without any elevator input, the model start pitching up and down. The oscillations are very fast and violent and usually end up in a crash. ......The only common thing if i really think about it would be that it would happen during gusty wind condition but that would only be flying during sea breeze which is about 15 - 18km/h......
Jan, the AMOUNT of wind is not the issue. As you say it's still flyable. But perhaps there's something going on with the flying site you're using which causes some nasty rotors to form downwind of some building or geographic feature at this flying site. By any chance is there a grove of trees or a cliff located upwind from the spot where you mostly find you lose control? Is your flying field downwind on these days from a group of houses or other buildings?

The fact that you can pretty well go for some number of flights on other days without issue and on multiple airplanes and sets of gear says that it's not you, the gear or the models. And with some thinking about the conditions I bet you'll start to remember that there's more to this wind issue and wind direction coupled with the crashes than meets the eye. Did many or all of your loss of control moments occur in a fairly limited area during these particular wind conditions? I'm thinking that there is a link here since it seems to be the only common item you've brought to the discussion.
Old 12-31-2015, 11:20 AM
  #44  
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You have changed your radio gear so you should be able to rule out radio gear as long as you are on 2.4 . If this is something that is happening only to you then it must be something that you are doing wrong . Its hard to say why it only happens after you have been flying a model for a long while . We don't know your maintentince habits . Do you keep a watch on your linkages for slop ect. How do you store your planes?. Is there a possibility for something to move changing the C of G ? Are you flying glow fuel and does this happen closer to the end of a flight? That would indicate a tail heavy condicition . Maybe you need to balance using a more acurate method than your fingers . I am not so sure it is balance unless something has suddenly changed the balance . It may be a combination of things . Have you ever had a chance to fly one of these planes again after one of these incidences with any success ? If you have and it flys okay then pilot error would start to become suspect . Is that a possibility? If you have not had the chance to fly one of them again afer a crash, then you should have at least had the oppertunity to closly examine the elevator system on one ore two to see why it failed . I have seen a lot of crashes and often the tail section is still intact.
Old 12-31-2015, 11:36 AM
  #45  
bikerbc
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Maybe you could try some expo on the elevator and see if that helps .Its not hard to over control . Does this happen at other sites or only at home? Is it always in the same spot going in the same direction and is the wind always going in the same direction ? Have you ever asked another pilot to fly your plane too see if it happens to him too ? More information about your plane , the site you fly at , if you fly at other sites , would help us to help you .

Last edited by bikerbc; 12-31-2015 at 03:02 PM.
Old 01-02-2016, 10:33 PM
  #46  
zemanski99
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Hi guys, thank you all for your help. I've just fixed my last plane which I crashed, "The Ugly Stick" and will take some pictures of the set up and also some shots of our flying field so you will have more to go on.

OK I did fix The Stick, the last one that I crashed. Came down due to the same problem with elevator jinxing the plane up and down like a yo-yo, but when it hit the deck it was not too bad. Smashed the cowl, broke the prop, partly ripped out the motor and the landing gear. Checked it all after crash, the battery did not moved, servos OK and connection to elevator solid.

I fixed it all, left the servos in the plane and this Sunday had 4 normal flights with no problem whatsoever.

Now what I am starting to wonder is, as I am the only one in the club using the JR XG14 radio running the DMSS protocol if I don't have interference from some local signal. About 2km from our flying field are municipal waste ponds and I took a drive there and sure enough they have couple of small aerials on the roof of the maintenance building which could be use to remotely operate some instruments or valves in the pipelines from the ponds. It could be that the signal from them is not effecting anyone flying Futaba or Spectrum but my JR DMSS system is sensitive to it.

Is this possible? Could the interference effect just one channel on the 2.4 GHz system? I would think if I get interference it would effect all channels on my radio and I would be loosing more then just elevator control. Are any of you know how the 2.4 system actually works when hit by interference, can it effect just the single channel?

If I don't find the answer and if I have one more crash, then the only solution for me would be switch to Futaba which will be expensive with change of 10 receivers. So any ideas in regards to the signal interference on the single channel of the 2.4 system would be most welcome, best Jan

Last edited by zemanski99; 01-03-2016 at 03:33 PM.
Old 01-05-2016, 12:51 PM
  #47  
bikerbc
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I would try hooking up a reciever with a servo in the elevator spot C/W a battery and switch etc Bind it to your Transmitter and turn it all on around the same time you had the interferience and just sit and watch . Who knows you might catch it doing something . Can you rember if your interferience has been around a certain time?
Old 01-05-2016, 01:40 PM
  #48  
wcmorrison
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I use Hitech equipment. One of the foremost experts on the Aurora Hitech Transmitter is Alan Tong who is located in New Zealand. He runs a hobby shop somewhere in your homeland. Perhaps you can do a search of his name and locate him. He is very good at figuring out your kind of problem even though it is not Hitech equipment. He would certainly be very up on your kinds of interference.
Old 01-05-2016, 02:34 PM
  #49  
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So many requests for information and pictures with none provided.

You are an the other side of the planet, we want pics, but we need pics.

Please take pics of:
The radio installation.
The servo installation.
The control surface connections.
Give settings for:
Elevator control throws, end points, expo, high and lo rates.
Any switches being used.
Any mixes or modes.
Any programs.

All the info you've provided so far seems to point toward something other then where you are looking.

.02
Old 08-19-2023, 10:15 AM
  #50  
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Did I miss something or is this Issue just to be left hanging in the air? What happened?? Do you still have the problem after all these years or what???

There is no sin in saying I DON'T KNOW!

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