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Old Nov 29, 2012, 04:57 PM
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Here are some pictures (not too good unfortunately). As you can see the rudder is being pulled to one side, if i push it over to the other it will just jump back to where it is in the picture. If I attach the servo wire it stays centered of course but as I said the servo sounds like it has to work harder to pull it in the other direction.
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Old Nov 29, 2012, 05:35 PM
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Good pictures.. I honestly can't see a thing wrong here. I compared the pictures with my two Funcubs and they look just like yours. I think it must be a servo problem. At least your construction is exactly the way it's supposed to be.
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Old Nov 29, 2012, 06:11 PM
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probably just need to break in the hinge a bit its probably too stiff
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Old Nov 29, 2012, 06:16 PM
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Originally Posted by shadow102 View Post
probably just need to break in the hinge a bit its probably too stiff
hmm... could be.. Although the servo would most likely keep the rudder in position. Unless the hinge is really stiff. Well worth the time to check!
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Old Nov 29, 2012, 06:49 PM
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Originally Posted by kjur View Post
Here are some pictures (not too good unfortunately). As you can see the rudder is being pulled to one side, if i push it over to the other it will just jump back to where it is in the picture. If I attach the servo wire it stays centered of course but as I said the servo sounds like it has to work harder to pull it in the other direction.
In the first picture it looks like the tailwheel pivot that is glued into the fuselage is pressing up against the bottom of the rudder control horn. It also looks like that pivot may be to the left a bit at the top and to the right a bit at the bottom. Might happen if the fin were pressed down to far when gluing it in. If you pull straight up on the fin while holding the fuse near the tail does the rudder straighten out?

Update: I just zoomed in on that photo and it looks like there might be glue between the tailwheel pivot and the bottom of the rudder. Is there? If so that would certainly account for the tail wanting to stay in one place!

Gord
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Last edited by Gordks; Nov 29, 2012 at 06:57 PM.
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Old Nov 29, 2012, 06:58 PM
Happy on 72
USA, CA, Santa Clarita
Joined Jul 2005
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Originally Posted by kjur View Post
I just assembled my RR version of the Fun Cub and when I glued the rudder in place I noticed that it's pulling to the right all the time, it must be bent somehow. I inserted that plastic part at the bottom first with some glue and then pushed it down a little and glued it onto the horizontal stabilizer.

So when I move the rudder to the left and release it, it just goes back to the right side, like there was a spring atached to it.

I connected the servo and the whole plane is kind of vibrating a little when I move the rudder, sounds like it is working much harder compared to the other servos.

Anyone had a similar problem? I don't think I'll be able to remove the rudder again without ruining it.
Do you think it is okay for the servo anyway?
I wouldn't leave it like that; it puts unnecessary strain on the servo which can drain your batteries a bit more. If the foam is too stiff and not allowing the rudder to center, I would cut the hinge and then reattache the rudder with some flexible tape, leaving enough space so it can move freely.

Mike
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Old Nov 30, 2012, 12:59 AM
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If there is not any thing (e.g horn, glue blob) obviously pushing the rudder to the right (it would be easy to check) and your rudder/vertical stab look reasonaby straight (not twisted or anything) it must be either:
-the plastic hinge. It could be too stiff or some glue might have soaked in (especially if you used thin CA) or it simply needs to "break in".
-the foam hinge (connecting rudder to vertical stab) needs to break in.

Grab the plastic hinge and move rudder left&right several times to see if it gets any better. If not, try to put some CA solvent (if CA is what you ve used) in the plastic hinge (google "how to remove CA").

Just some ideas that came to mind

PS: In the past, I needed to take out the plastic hinge from the side of the fuselage. I just stuck an exacto between hinge and fuselage and then it was easy to pull apart. I wouldn't try to take out the hinge from the side of the rudder - it would ruin the rudder.
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Old Nov 30, 2012, 01:22 AM
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Japan, Miyagi Prefecture
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Quote:
Originally Posted by kjur View Post
Here are some pictures (not too good unfortunately). As you can see the rudder is being pulled to one side, if i push it over to the other it will just jump back to where it is in the picture. If I attach the servo wire it stays centered of course but as I said the servo sounds like it has to work harder to pull it in the other direction.
I've pored over your photos looking for something obviously wrong, but nothing really stands out. There does seem to be a bit of twist or distortion at the point where the plastic hinge and wire enter the rudder, which might have something to do with it.

Do you remember how the vertical stab/rudder was before you assembled the model? Were they aligned then? If so, it's something you've done in the build, and not the foam hinge.

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Old Nov 30, 2012, 10:32 AM
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Thank you all very much for the replies!

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Originally Posted by FunPilot View Post
I've pored over your photos looking for something obviously wrong, but nothing really stands out. There does seem to be a bit of twist or distortion at the point where the plastic hinge and wire enter the rudder, which might have something to do with it.

Do you remember how the vertical stab/rudder was before you assembled the model? Were they aligned then? If so, it's something you've done in the build, and not the foam hinge.

Yes I think you are right. The rudder was good and aligned before I assembled the model.
As I said earlier it is a RR model so the tail wheel and hinge was already on the rudder when I got it.
So I put the hinge into the fuselage and it looked good, then I put some glue on it and put it in the fuselage.
But there was a small gap between the vertical stab and the horizantal stab so I had to push it down just a little to glue it in place.
I made a picture in paint to show what I mean.

It looked something like this, not nearly as much as in my picture of course, but a little, so maybe that's what causing the rudder to not stay centered.

Perhaps after a while it will be loosened up and easier for the servo to move? I pushed the rudder to the other side and taped it and left it like that until I came home two hours ago. It feels like it might have helped a little bit. So maybe it will get better with time.

Also wanted to ask about the glue I use. I used Zacki Elapor before but when there was nothing left I bought something called "Super Glue - Universal - Cyanoacrylate", that's about all it says. It came with activator. Does that sound like the right thing to use?
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Old Nov 30, 2012, 10:41 AM
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United States, FL, West Melbourne
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Originally Posted by Sammy70 View Post
We have 3 FunCubs in service and have flown them all with CGs anywhere from 55-75mm with no problems at all...

As CG moves forward stall speed increases. Have you seen this with the CG at 55? I find a delighfully slow flying plane with it back at 70-75.
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Old Nov 30, 2012, 11:48 AM
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@ Kjur- If you put nylon hinges in slightly off centerline...you get the same effect as you are having...I would BET it is the tail wheel wire ( weather you can see it or not)...B4 I cut the hinged rudder ....I would remove the tail wheel wire...and see if that clears the problemb up...if it Does...simply straighten it..and reinstall it.
My 2Cents worth
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Old Nov 30, 2012, 04:31 PM
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Originally Posted by Weed89 View Post
@ Kjur- If you put nylon hinges in slightly off centerline...you get the same effect as you are having...I would BET it is the tail wheel wire ( weather you can see it or not)...B4 I cut the hinged rudder ....I would remove the tail wheel wire...and see if that clears the problemb up...if it Does...simply straighten it..and reinstall it.
My 2Cents worth
Hmm thanks I might try that, but I'm not sure how to remove the tail wheel wire. Going to have to look into that.
But I think I'll do the maiden flight tomorrow and leave it as it is right now. It seems to be a little better now.

I bought some servo reversers for use with the flap servo a few days ago but it will take a week or two to get them so I thought I'd try some mixing.
I was searching on google and found some things that helped me and this is what it looks like right now: (one flap servo is in channel 5 "GEAR" and one in channel 6 "AUX 1")


MIX 1
FLAP→ GEAR ACT
RATE D +100% U +100%
SW ON TRIM ACT


MIX 2
GEAR→ GEAR ACT
RATE D -100% U -100%
SW ON TRIM INH


And then I experimented with the flaps menu because the flaps were at around a 45 degree angle.

FLAPS
FLAP
NORM ↑ 88
LAND ↓ 60

Now one of them was leveled with the wing but not the other one.
So I experimented with SUB TRIM

and added ↑10 on GEAR and now both are looking pretty good.


Do you think something looks wrong? I haven't really done this before.
Are there any pros/cons of using this compared to a y harness and reverser? Should I just fly without the flaps until I have the reverser? Perhaps a reverser is more reliable than this?

Sorry, many questions. Again, thanks everybody!
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Old Nov 30, 2012, 05:28 PM
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there is suppose to be a little extra straight run of the tail wheel wire as it exits the hinge/pivot plastic piece. Yours looks bent back as soon as it exits, maybe causing a bind.
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Old Nov 30, 2012, 06:01 PM
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Originally Posted by Bluhammer View Post
there is suppose to be a little extra straight run of the tail wheel wire as it exits the hinge/pivot plastic piece. Yours looks bent back as soon as it exits, maybe causing a bind.
Yes you are right, thanks. i'll try to straighten it and bend it further down.




I also wanted to ask if the way I have placed my AR6210 is optimal?
I put it on the side of the fuselage like this using velcro. the satellite is on the same side but in a different angle.
It says that they should be "oriented perpendicularly to each other", not sure if that's what I've done.

The receiver is unfortunately directly above the hole but it was hard to reach in there.
Do you think it looks okay?
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Old Nov 30, 2012, 06:26 PM
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United States, CA, Thousand Oaks
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you will be just fine Dont Over think Too many things..Keep it fun...but DO try and fix that tail wheel/wire...binding is NOT your friend.

Your placement of Rx looks just fine ....also, flaps are simple to fly with...the hard part will be training your hand/finger to find the correct switch to operate it...but the cub is a pussycat...and Full flaps will really decrease the speed and area it takes to land...just slow b4 you deploy and all will be fine...my spectrum lets me SLOW the servo speed...so I dont even have any pitch change when i drop flaps...because they deploy slowly

Like many others here I recomend your CG around 70~75mm back from the leading eadge << or aprox middle of the front spar.` ish
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