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Old Dec 23, 2012, 11:20 AM
Lee
PERFECT LANDING !!!
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USA, UT, Orem
Joined Jul 2004
8,939 Posts
You often can see the flex in the linkage system best when the servos are pushing the rods not pulling. Do a couple of outside loops and see how the plane performs. To prevent accidents it is easier to go from inverted flight to an outside loop rather than diving at the ground hoping the plane will make the loop before you know for sure.

In normal flight mini servos work but we have seen that the stresses of the heavy planes and the high speed flying require more servo power than the mini servos can give. I had a couple of customers who reported flutter that went away when they put the bigger servos in their plane and maximized the leverage between the servo and the elevon by:


1) Let the servo make full rotation. Don't use the transmitter to restrict movement.
2) Attach the push rod at the top of the horn on the elevon
3) Attach the push rod as close to the center of the servo arm as possible and still get adequate movement.
4) Use enough rod guides along the push rod to prevent any slack or flex
5) Make sure the servo is glued firmly in the foam and can't move even under stress

Another cause of flutter is that the rods are breaking loose from the wing with the extreme forces. This has been seen when:

1) Gorilla Glue has been used and after a few hard landings it starts to break down allowing the rods to move in the foam
2) The rods were not sanded during construction and or the glue did not stick to them
3) The rods are not tied together at the connecting points and are able to move against each other
4) The Extreme tape is not tight enough or applied in the right places.

I trust our elevon system but it has to be built right. I am using the EPP elevons even on my big planes like the Herc video you just watched in post 4633 and the 78" and 8 lb Herc video below.
You have to build for the style of flying you are going to do. If you want a bullet plane you have to build the plane to handle the stresses.


1) You can add another layer of laminate even after the plane is finished if the elevons are not stiff enough.
2) Double check your hinges and make sure they are tight. If you have too big of a gap in the hinge line or the hinge line isn't straight the hinge will be loose.

Lee

78" Hercules Wind Surfing (5 min 57 sec)
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Last edited by Lee; Dec 23, 2012 at 11:41 AM.
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Old Dec 23, 2012, 12:30 PM
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United States, CT, New Haven
Joined Dec 2011
166 Posts
Thanks for the response. I am sure it is builder error for I m fairly new at this. This is my 3rd CTH build. I am going to check everything out before I go out and fly. Note, I didn't do this on 3s with 8x4 prop at 700w or more. I was also liberal with he hot glue on the spar install and also the e-tape.
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Old Dec 23, 2012, 01:42 PM
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United States, MI, Detroit
Joined Feb 2004
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Lee- I would have people try the white gorilla glue. It flexes a little and might be able to withstand impacts better than a rigid yellow glue.
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Old Dec 23, 2012, 01:56 PM
UH60 Pilot
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United States, KY, Fort Campbell
Joined Jan 2010
273 Posts
Quote:
Originally Posted by cmaynex View Post
Thanks for the response. I am sure it is builder error for I m fairly new at this. This is my 3rd CTH build. I am going to check everything out before I go out and fly. Note, I didn't do this on 3s with 8x4 prop at 700w or more. I was also liberal with he hot glue on the spar install and also the e-tape.
Throw some pictures up or a quick YouTube video. At least your setup so we can take a look at it.
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Old Dec 23, 2012, 01:58 PM
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United States, KY, Fort Campbell
Joined Jan 2010
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Quote:
Originally Posted by ashdec87 View Post
Lee- I would have people try the white gorilla glue. It flexes a little and might be able to withstand impacts better than a rigid yellow glue.
I have one reaper spar with hot glue and the other with white gorilla glue. Unfortunately as it sits I won't be able to smash it up in combat as no one is around. I do want to see the difference between the glue methods
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Old Dec 23, 2012, 02:28 PM
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United States, MI, Detroit
Joined Feb 2004
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the issue I've had with hot glue is that it becomes brittle in cold weather and can release from the surrounding foam. In hot weather it can get just soft enough to allow the spar to wiggle out. I've have planes fall apart because of the heat of summer (thankfully on the ground).
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Old Dec 23, 2012, 03:45 PM
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United States, CT, New Haven
Joined Dec 2011
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Made sure everything was tight and I noticed that the laminate was coming loose so I re-ironed it and no more high speed flutter. Just came back from the park flying her full throttle against and with the wind.
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Old Dec 23, 2012, 04:36 PM
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United States, KY, Fort Campbell
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Sounds like problem solved
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Old Dec 23, 2012, 04:39 PM
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I do have video but it is not appropriate for this site and youtube. A little bit of cursing. I do not know how to edit out sound or edit a video period. I would like to start posting videos.
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Last edited by cmaynex; Dec 23, 2012 at 04:51 PM.
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Old Dec 23, 2012, 06:10 PM
UH60 Pilot
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United States, KY, Fort Campbell
Joined Jan 2010
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I don't think YouTube or us mind all too much about your sailor style talk!
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Old Dec 23, 2012, 07:36 PM
UH60 Pilot
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United States, KY, Fort Campbell
Joined Jan 2010
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YouTube you can completely overlay music on your audio.
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Old Dec 23, 2012, 09:24 PM
wheeeeee!
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United States, UT, Provo
Joined Oct 2011
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Quote:
Originally Posted by ashdec87 View Post
Lee- I would have people try the white gorilla glue. It flexes a little and might be able to withstand impacts better than a rigid yellow glue.
Unfortunately, the white gg is still not flexible enough (and clearly not as flexible as hot glue). My bro-in-law's plane that I mentioned before, he built entirely with white gg... well, sure enough, it wasn't long before a few crashes had the spars loose, and chunks of gg floating around under the lam. Now that it's in half, pretty much, he's rebuilding with hot glue.
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Old Dec 24, 2012, 06:44 AM
Lee
PERFECT LANDING !!!
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USA, UT, Orem
Joined Jul 2004
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I only use the hot glue. I build a lot of planes and it is definitely the fastest. I don't remember a glue joint failing. I think the Gorilla glue may get weaker if it gets too much water (used for activation) in it when it is applied.
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Old Dec 24, 2012, 07:35 AM
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United States, KY, Fort Campbell
Joined Jan 2010
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3536-1800kv back in stock
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Old Dec 24, 2012, 08:27 PM
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Australia, QLD, Mountain Creek
Joined May 2012
151 Posts
Grim Reaper and box of HobbyKing bits arrived a week ago and were stashed by the family. They ärrived"under the tree this morning. Happy Days.


A merry Christmas and a crash free new year to Lee and all the Crash Test Hobbyists from our family in Australia
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