Notices
Questions and Answers If you have general RC questions or answers discuss it here.

Sealing Hinge lines

Old 02-25-2008, 07:29 PM
  #1  
masonman
Senior Member
Thread Starter
 
Join Date: Oct 2006
Location: Wynne, AR
Posts: 531
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Sealing Hinge lines

I have been told that i need to start sealing my hinge lines to take away the chance of flutter on my models.
I understand how to do it,Just not sure if i need to do the top or bottom or both when it comes to the surfaces?
Am i supose to do the rudder?
Do I have to use clear ultra-cote or is there an alternative?


Many thanks for ideas regarding this topic
masonman is offline  
Old 02-25-2008, 07:31 PM
  #2  
Ed_Moorman
My Feedback: (1)
 
Ed_Moorman's Avatar
 
Join Date: Jan 2002
Location: Shalimar, FL
Posts: 4,059
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

I always seal my ailerons and sometimes do the elevator. I use clear, 3M packaging tape. Do it on the bottom.

Ed_Moorman is offline  
Old 02-25-2008, 07:44 PM
  #3  
masonman
Senior Member
Thread Starter
 
Join Date: Oct 2006
Location: Wynne, AR
Posts: 531
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Thanks Ed. Should i heat the tape up with an iron? Should i do the rudder or not? will sealing make my models fly diffrent in any way?
masonman is offline  
Old 02-25-2008, 09:00 PM
  #4  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Just for the record,

Fact: Sealing the hinge line will make your control surfaces a little more effective, but mostly if you presently have large gaps.

Myth: Sealing the hinge line will reduce the chance of flutter.

I always used to seal them too - haven't done it in about 15 years

And I don't get any flutter - even with large control surfaces and at high speeds
MinnFlyer is offline  
Old 02-26-2008, 05:46 AM
  #5  
Ed Smith
Senior Member
 
Join Date: Dec 2001
Location: Brantford, ON, CANADA
Posts: 3,305
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

The hinges on any control surface have to allow the surface to move freely. This is not the cause of flutter. Two things cause flutter, a soft flexible control surface and/or a sloppy servo/pushrod/horn connection. Sealing the hinge line makes the control surface more effective compared to a non sealed hinge line.

Ed S
Ed Smith is offline  
Old 02-26-2008, 07:32 AM
  #6  
jetmech05
 
Join Date: Jul 2005
Location: Jacksonville, FL
Posts: 4,855
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Just like anything else flutter is caused by different things.....wing sweep, or cord, slop, gap, speed and usually it takes a combonation of two or more to get a flutter...By sealing the hinge gap you reduce the chance of flutter to near zero..
I've never been struck by lightning, Ive never even seen anyone struck by lightning..but I know it happens.....
whether you need to seal your hinge lines depends on how you fly and what you fly...but flutter is airflow passing through the hinge line in one direction causing the control surface to deflect..once deflected the flow reverses, causing the surface to deflect the opposite way. This happens very rapidly, causing the buzzing sound, that can lead to the airframe coming apart.
I've seen flutter twice once led to a broken horizontal stab..the other was on my 4 Star 60 after an aileron servo failure. thankfully it had dual aileron servos.
jetmech05 is offline  
Old 02-26-2008, 07:58 AM
  #7  
Zippi
Senior Member
My Feedback: (10)
 
Zippi's Avatar
 
Join Date: Jun 2004
Location: Evansville, IN
Posts: 4,970
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

masonman,

I always seal my control surfaces with clear Monokote on the bottom only and I do not seal the rudder. I think jetmech05 said it pretty well, if you have a good strong servo and a good strong control rod with very little slop that will stop most flutter if it's going to happen. Now, there is the exception to the rule. I have seen guys that have a gap big enough you could throw a cat through it . Nothing is going to help that situation. When putting these planes together, you have to make sure you have the LE & TE as close as possible and still mantain the deflection you need for your style of flying.
Zippi is offline  
Old 02-26-2008, 09:03 AM
  #8  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines


ORIGINAL: jetmech05

By sealing the hinge gap you reduce the chance of flutter to near zero..
This is total BS


ORIGINAL: jetmech05

flutter is airflow passing through the hinge line in one direction causing the control surface to deflect..once deflected the flow reverses, causing the surface to deflect the opposite way.
Again, total BS. This is the misconception of flutter.

It is like saying that if you seal a flag to the pole it will stop waving.

Sealing the hinge gaps will NOT prevent flutter - I have SEEN flutter happen on control surface that were sealed.

If you want to improve a control surface's effectiveness, seal the gap

If you want to prevent flutter, use a servo that is strong enough to hold the surface tightly (The bigger the surface, the stronger the servo needed) and remove all slop from the linkages.
MinnFlyer is offline  
Old 02-26-2008, 09:06 AM
  #9  
da Rock
Senior Member
 
Join Date: Oct 2005
Location: Near Pfafftown NC
Posts: 11,511
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Uh oh...........

Bickering is about to start because it needs to..............

Unfortunately, sealing the hinge line will not reduce the chance of flutter to near zero. There are two major contributions that sealing can give to reduce flutter. It can and will reduce the looseness of the surface and stiffen it's play. And sealing stops the disruption of airflow and pressure through the gaps. Stiffening certainly helps. Smoothing the airflow can help.

But sealing doesn't even approach being a halfway dependable cure much less a guaranteed one. Last year there were at least two IMAC models that experienced flutter at our club field. Both had fully sealed hinge lines. Every hinge line on the models. It's almost standard practice with competition models to improve precision. And it's actually quite common for guys who fly sealed-gap models to work very hard including the things that actually affect flutter, no-slop rigging and stiff surfaces.

Wings that had absolutely no ailerons or flaps on them at all fluttered and failed with regularity in the early days of flight when not all wings had ailerons. Matter of fact, the airplanes that controlled roll with wing-warping suffered from flutter, and there were no hinge lines in those suckers at all. Those wings were marginally stiff and most importantly, the rigging wasn't strong enough to hold the surfaces steady... the two most important players in flutter. And in modern times, there are documented cases of allmoving tailplanes and such suffering from flutter.




(Jeez, I wish I'd thought about the flag/flagpole analogy......
Or seen your post before starting mine..... )














da Rock is offline  
Old 02-26-2008, 09:31 AM
  #10  
Rodney
Senior Member
 
Join Date: Dec 2001
Location: FL
Posts: 7,769
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Miniflyer and DaRock. Good for you and your comments and you are so correct. I do not know how many people erroneously insist tapeing the gap cures flutter. There is one possible way that the taping might reduce the flutter, if it is heavy enough and stiff enough to change the physical properties of the moveable surface, then it might help reduce flutter or at least make it happen at a different frequency but it is definately not a cure.
Rodney is offline  
Old 02-26-2008, 10:21 AM
  #11  
TFF
 
Join Date: Oct 2006
Location: Memphis, TN
Posts: 4,183
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Sealing the gap does not prevent flutter it changes the frequency that it occurs. You may be lucky that it moved it out of your operating range, which is why you try it, but all flight controls will flutter given the right speed. Tight push-rods are a given and balancing may be necessary, too.
TFF is offline  
Old 02-26-2008, 10:27 AM
  #12  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines


ORIGINAL: TFF

Sealing the gap does not prevent flutter it changes the frequency that it occurs.
Exactly - and you might be unlucky enough that it moves it to a more noticeable range!
MinnFlyer is offline  
Old 02-26-2008, 11:44 AM
  #13  
JRFisher
Senior Member
 
JRFisher's Avatar
 
Join Date: Jun 2003
Location: Pittsburgh, PA
Posts: 153
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

A while back I took MinnFlyer's advice and stopped sealing my gaps.
I have all fun-fly type planes with very large control surfaces.
The only noticeable flutter I have is on one plane's rudder and that flutter is due to a worn hole in the servo arm.
Unless you have very large gaps, I'd forget it, fly, and have fun!
JRFisher is offline  
Old 02-26-2008, 02:37 PM
  #14  
masonman
Senior Member
Thread Starter
 
Join Date: Oct 2006
Location: Wynne, AR
Posts: 531
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

There not huge gaps.You can't drive a truck threw them,maybe a small suv

I have good hardware for linkages an very stronge metalgear HT servos.
I have never heard flutter before, but everyone says it spells c-r-a-s-h.
Lots of guys say it only happens when your model is going well over the speed it was intended to fly,Well I have a little toni that is way to fast an it does not have sealed hinges an it don't flutter, or slow down.[:@]
So I will just take the advise given an keep on doing it the way I have been...................Many thanks
masonman is offline  
Old 02-26-2008, 03:18 PM
  #15  
a68fan
Senior Member
 
Join Date: May 2003
Location: east coast
Posts: 175
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Hi Guys!!

This question is not about "flutter", but kinda' fits in....

I have a Sky Shark Sky Raider with a llittle tal wag at 3/4 plus throttle. No no waggle at lower throttle. It does have "Nyrod" for rudder control...

Any ideas??

Allen
a68fan is offline  
Old 02-26-2008, 05:16 PM
  #16  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

This is what's known as a harmonic vibration. everything has a frequency at which it wants to vibrate.

Your rudder wants to vibrate at whatever frequency you engine is vibrating when it's at 3/4 throttle.

You could try a couple of things:

First, I would check that the prop is balanced. That alone could very well be the culprit.

The other thing you could do is to add or remove weight to the rudder - which will change its frequency. You could also make the rudder bigger which willl do the same thing.
MinnFlyer is offline  
Old 02-27-2008, 03:47 PM
  #17  
a68fan
Senior Member
 
Join Date: May 2003
Location: east coast
Posts: 175
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Thank you very much!!

Sky Raider will go "under the knife" This evening....

Allen
a68fan is offline  
Old 02-27-2008, 07:16 PM
  #18  
masonman
Senior Member
Thread Starter
 
Join Date: Oct 2006
Location: Wynne, AR
Posts: 531
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

Hey minnflyer, How long have you been modeling? You have buckets full of info, an its not crappy info
masonman is offline  
Old 02-28-2008, 08:06 AM
  #19  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

I started when I was 5 yrs old. My dad was in the hobby, so I grew up with it. I can't ever recall a time when we didn't have a basement full of airplanes.

I'm 53 now

And BTW, my dad turns 87 next week and he still burns more fuel in a week than I do in a month!
MinnFlyer is offline  
Old 02-28-2008, 08:37 AM
  #20  
JRFisher
Senior Member
 
JRFisher's Avatar
 
Join Date: Jun 2003
Location: Pittsburgh, PA
Posts: 153
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

MinnFlyer-

I'm about 3 years from retirement. I can't wait to start spending more money on fuel!!!
JRFisher is offline  
Old 02-28-2008, 08:39 AM
  #21  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

MinnFlyer is offline  
Old 02-28-2008, 12:41 PM
  #22  
Ed Smith
Senior Member
 
Join Date: Dec 2001
Location: Brantford, ON, CANADA
Posts: 3,305
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

I'm about 3 years from retirement. I can't wait to start spending more money on fuel!!!
Start stocking up now. The way oil prices are going model airplane fuel could be sound investment futures!

Ed S

Ed Smith is offline  
Old 02-28-2008, 04:08 PM
  #23  
jeffk464
Senior Member
 
Join Date: Oct 2004
Location: Lehi, UT
Posts: 1,692
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Sealing Hinge lines

I lost an aileron in-flight to flutter, thank goodness the manufacturer had enough foresight to install one on each wing or I could have lost the plane . . In my case the flutter was caused by going to fast with a plane designed to fly 3D. If you fly your plane in the way its designed to fly you shouldn't have any trouble.
jeffk464 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.