Christen Eagle II Vibration
06-07-2007, 07:38 AM
#1
Thread Starter
Join Date: Jul 2006
Location: Las Vegas,
NV
Posts: 46
Likes: 0
Received 0 Likes
on
0 Posts
Christen Eagle II Vibration
Hi,
On my Christen (Greatplanes model II) the top wing is vibrating a lot and cause the Robart hinge to fail. The Hinge are ok but the vibration erode the balsa from the wing side and then it start to get loose. This is only on the hinge close to the servo.
I'm running a brison 3.2. The vibration at idle are fine (after leaning it) but get blurry between 3000 and 6000 RPM. Only the top wing is having this harmonic vibration problem and the rest of the plane is fine. I can even hear when the resonance start as the fuse emit a strange sound.
The prop and spinner are well balance and I do not think that the engine has a bented shaft. The only think is that the bearing on the rod is having some slop but it seams to be normal for a Brison.
I double the number of hinge of the servo side and it seams to last longer now.
I already read a lot in this forum and the source of information is huge however I would appreciate your comment on similar problem.
Thanks for your help as usual.
On my Christen (Greatplanes model II) the top wing is vibrating a lot and cause the Robart hinge to fail. The Hinge are ok but the vibration erode the balsa from the wing side and then it start to get loose. This is only on the hinge close to the servo.
I'm running a brison 3.2. The vibration at idle are fine (after leaning it) but get blurry between 3000 and 6000 RPM. Only the top wing is having this harmonic vibration problem and the rest of the plane is fine. I can even hear when the resonance start as the fuse emit a strange sound.
The prop and spinner are well balance and I do not think that the engine has a bented shaft. The only think is that the bearing on the rod is having some slop but it seams to be normal for a Brison.
I double the number of hinge of the servo side and it seams to last longer now.
I already read a lot in this forum and the source of information is huge however I would appreciate your comment on similar problem.
Thanks for your help as usual.
06-10-2007, 09:57 AM
#2
Member
My Feedback: (8)
Join Date: Nov 2004
Location: Bradenton,
FL
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts
RE: Christen Eagle II Vibration
Icarron, I have the same plane with robart hinges all around.Had a fuji BT64 EI shook the plane to pieces. If you are sure your prop and spinner are balanced perferctly look at the very tips of the wings when at 1/2 throttle. If they are vibrating up and down 1/8 to 3/16" something is bent. I had two brand new fuji's with bent cranks. The first was .018" out of round in 170 degrees the second was .025" out in 170 the last was .002". I ran the engine for four minutes and broke the 90 degree wing mount on the leading edge for the third time. The cabanes are the first to go then the wing mounts. I have posted pics of mine on the build and mods thread. If you have the ability to have a set made (CNC) from .086" steel that takes care of that flaw. I have a guy making me a set of aluminum wing mounts out of 6064 one piece cost about 20.00-25.00 dollars.http://www.rcuniverse.com/forum/m_13...2Ceagle/tm.htm (http://www.rcuniverse.com/forum/m_13...2Ceagle/tm.htm)Post #280 The only thing I can help with is check to see if at the top of the fire wall the two 3/8' * 3/4 spruce rails are still glurd firmly.They are what holds the wing on.If it sounds like a snare drum when you throttle up your crank is bent.Hop this helps.
