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Flutter Question

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Dennis.Kirby(at)kirtland.
Guest

Posted: Tue Sep 26, 2006 5:46 pm Post subject: Flutter Question

Kolb Friends -



I suspect I've had my first encounter with flutter on my Mark-3.

Not sure - that's why I'm asking this question: Can aileron flutter

happen in short bursts (like, durations less than one second)?



I was flying this morning in mildly turbulent air.  Cruise power,

straight & level at about 65 mph indicated.  I encountered a sudden

burst of vibration in the airframe that felt like (if you can picture

this) someone threw a big glop of oatmeal thru the prop.  Just one short

burst - not a continuous vibration.  At first I thought something soft

went thru my prop, like a rag or something.  



Lemme tell you - this is something that will make you sit bolt upright,

eyes wide, and make you wonder, "What the heck was THAT?"



My plane IS equipped with the aileron counterbalance rods (thanks again,

J.Hauck), but they are slightly shortened to accommodate wing folding.



This happened four different times in my 1.2 hour flight.  Aside from

that, everything was working fine (engine), and my postflight inspection

revealed no anomalies.  Except ...



I had repaired some fabric on the outboard trailing edge of the right

aileron a week before this flight.  In doing so, the outboard six inches

of aileron gap seal fabric (I use bookbinding tape) was removed.  And

not re-installed, after the fabric fix.  I suspect the new airflow

pattern due to the missing tape, plus the extra weight of the fabric

patch/paint on the aileron, was enough to initiate the flutter.  



Anybody think this could be the cause?



I will definitely reinstall the gap seal tape before next flight - see

if that cures the problem.



Dennis Kirby

Cedar Crest, NM

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Tue Sep 26, 2006 6:05 pm Post subject: Flutter Question

Possibly aileron flutter. Watch it. If it flutters, you can see it. I had 

some rudder flutter, but it was sort of long duration, not so much a flutter 

as a waggle. But totally unacceptable. And it only happened if you took your 

feet off the pedals. Replace that tape muy pronto and see how it does.



Richard Pike

MKIII N420P (420ldPoops)

---

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

jindoguy(at)gmail.com
Guest

Posted: Tue Sep 26, 2006 6:48 pm Post subject: Flutter Question

Dennis, You say the counter balances were shortened. Are they still in balance? If in doubt, disconnect your aileron push rods at the aileron bell crank and check. The combination of patch and shortening could very well be the cause of a flutter episode. It certainly sounds exactly like my first flutter incident. Airspeed was about the same, and it did come and go like that at first. I had no counter weights. Installing them and doing a careful balance has the flutter threshold beyond 120 mph, now. 



Rick



On 9/26/06, Kirby Dennis Contr MDA/AL <Dennis.Kirby(at)kirtland.af.mil (Dennis.Kirby(at)kirtland.af.mil)> wrote:  	  Quote: 	
		  --> Kolb-List message posted by: "Kirby Dennis Contr MDA/AL" < Dennis.Kirby(at)kirtland.af.mil (Dennis.Kirby(at)kirtland.af.mil)>



Kolb Friends -



I suspect I've had my first encounter with flutter on my Mark-3.

Not sure - that's why I'm asking this question: Can aileron flutter

happen in short bursts (like, durations less than one second)? 



I was flying this morning in mildly turbulent air.  Cruise power,

straight & level at about 65 mph indicated.  I encountered a sudden

burst of vibration in the airframe that felt like (if you can picture 

this) someone threw a big glop of oatmeal thru the prop.  Just one short

burst - not a continuous vibration.  At first I thought something soft

went thru my prop, like a rag or something.



Lemme tell you - this is something that will make you sit bolt upright, 

eyes wide, and make you wonder, "What the heck was THAT?"



My plane IS equipped with the aileron counterbalance rods (thanks again,

J.Hauck), but they are slightly shortened to accommodate wing folding. 



This happened four different times in my 1.2 hour flight.  Aside from

that, everything was working fine (engine), and my postflight inspection

revealed no anomalies.  Except ...



I had repaired some fabric on the outboard trailing edge of the right 

aileron a week before this flight.  In doing so, the outboard six inches

of aileron gap seal fabric (I use bookbinding tape) was removed.  And

not re-installed, after the fabric fix.  I suspect the new airflow

 pattern due to the missing tape, plus the extra weight of the fabric

patch/paint on the aileron, was enough to initiate the flutter.



Anybody think this could be the cause?



I will definitely reinstall the gap seal tape before next flight - see 



	


-- 

Rick Girard

"Ya'll drop on in"

takes on a whole new meaning

when you live at the airport.  [quote][b]

NeilsenRM(at)comcast.net
Guest

Posted: Tue Sep 26, 2006 7:41 pm Post subject: Flutter Question

Rick

  

 You keep saying 120 MPH!!!! I suspect your airspeed  indicator is giving you higher readings than actual speeds. The published  VNE on a MKIIIc is 100 MPH. If I remember the other speeds correctly you  were quoting were a bit high for the engine you are running. That was a 582? Any  way, if you really were going 120 MPH then you are a very lucky individual. I  would not recommend that anyone try to duplicate this feat unless you are trying  to rip your wings off.

  

 My $.02 worth.

  

 Rick Neilsen

 Redrive VW powered MKIIIc 

 [quote]   ---

planecrazydld(at)yahoo.co
Guest

Posted: Wed Sep 27, 2006 2:24 am Post subject: Flutter Question

Hi Dennis;

  You may have identified the primary cause but eventual loosening of structural assemblies due to use and wear can also bring flutter on.

  



Kirby Dennis Contr MDA/AL <Dennis.Kirby(at)kirtland.af.mil> wrote:

  [quote]--> Kolb-List message posted by: "Kirby Dennis Contr MDA/AL" 



Kolb Friends -



I suspect I've had my first encounter with flutter on my Mark-3.

Not sure - that's why I'm asking this question: Can aileron flutter

happen in short bursts (like, durations less than one second)?



I was flying this morning in mildly turbulent air. Cruise power,

straight & level at about 65 mph indicated. I encountered a sudden

burst of vibration in the airframe that felt like (if you can picture

this) someone threw a big glop of oatmeal thru the prop. Just  one short

burst - not a continuous vibration. At first I thought something soft

went thru my prop, like a rag or something. 



Lemme tell you - this is something that will make you sit bolt upright,

eyes wide, and make you wonder, "What the heck was THAT?"



My plane IS equipped with the aileron counterbalance rods (thanks again,

J.Hauck), but they are slightly shortened to accommodate wing folding.



This happened four different times in my 1.2 hour flight. Aside from

that, everything was working fine (engine), and my postflight inspection

revealed no anomalies. Except ...



I had repaired some fabric on the outboard trailing edge of the right

aileron a week before this flight. In doing so, the outboard six inches

of aileron gap seal fabric (I use bookbinding tape) was removed. And

not re-installed, after the fabric fix. I suspect the new airflow

pattern due to the missing tape, plus the extra weight of the Dave Downey

 in SE PA

 Carpe Tigercubium

  	 		Get your own [url= http://us.rd.yahoo.com/evt=43290/*http://smallbusiness.yahoo.com/domains]web address for just $1.99/1st yr[/url]. We'll help.

jindoguy(at)gmail.com
Guest

Posted: Wed Sep 27, 2006 4:34 am Post subject: Flutter Question

Rick, 120 mph was what I got off the GPS while testing the aileron counter balance installation. During that brief excursion into the red zone, my discomfort level was in the red zone, too, but upon post flight inspection, I found no evidence of seat damage.  I would never recommend anything over mid yellow (max smooth air cruise speed), about 95 mph. To be honest, my goal was to get 10% over redline, but I made a bad entry into a chandelle and got too steep coming out. Needless to say I pulled back on the stick very, very gently. 



Rick



On 9/26/06, Richard & Martha Neilsen <NeilsenRM(at)comcast.net (NeilsenRM(at)comcast.net)> wrote:[quote]        Rick

  

 You keep saying 120 MPH!!!! I suspect your airspeed  indicator is giving you higher readings than actual speeds. The published  VNE on a MKIIIc is 100 MPH. If I remember the other speeds correctly you  were quoting were a bit high for the engine you are running. That was a 582? Any  way, if you really were going 120 MPH then you are a very lucky individual. I  would not recommend that anyone try to duplicate this feat unless you are trying  to rip your wings off.

  

 My $.02 worth.

  

 Rick Neilsen

 Redrive VW powered MKIIIc 

 [quote]   ---

Russ Kinne

Joined: 27 Jan 2006
Posts: 182

Posted: Wed Sep 27, 2006 5:31 am Post subject: Flutter Question

DaveDid you re-balance after shortening the rods and reworking the aeliron? Could be it.

CARPE KOLBIUM!

Russ



do noit archive



On Sep 27, 2006, at 6:22 AM, David Downey wrote:

 	  Quote: 	
		  Hi Dennis;

  You may have identified the primary cause but eventual loosening of structural assemblies due to use and wear can also bring flutter on.

  



Kirby Dennis Contr MDA/AL <Dennis.Kirby(at)kirtland.af.mil (Dennis.Kirby(at)kirtland.af.mil)> wrote:

   	  Quote: 	
		  --> Kolb-List message posted by: "Kirby Dennis Contr MDA/AL" 



Kolb Friends -



I suspect I've had my first encounter with flutter on my Mark-3.

Not sure - that's why I'm asking this question: Can aileron flutter

happen in short bursts (like, durations less than one second)?



I was flying this morning in mildly turbulent air. Cruise power,

straight & level at about 65 mph indicated. I encountered a sudden

burst of vibration in the airframe that felt like (if you can picture

this) someone threw a big glop of oatmeal thru the prop. Just one short

burst - not a continuous vibration. At first I thought something soft

went thru my prop, like a rag or something. 



Lemme tell you - this is something that will make you sit bolt upright,

eyes wide, and make you wonder, "What the heck was THAT?"



My plane IS equipped with the aileron counterbalance rods (thanks again,

J.Hauck), but they are slightly shortened to accommodate wing folding.



This happened four different times in my 1.2 hour flight. Aside from

that, everything was working fine (engine), and my postflight inspection

revealed no anomalies. Except ..



I had repaired some fabric on the outboard trailing edge of the right

aileron a week before this flight. In doing so, the outboard six inches

of aileron gap seal fabric (I use bookbinding tape) was removed. And

not re-installed, after the fabric fix. I suspect the new airflow

pattern due to the missing tape, plus the extra weight of the Dave Downey

 in SE PA

 Carpe Tigercubium

  	 		

Get your own [url= http://us.rd.yahoo.com/evt=43290/*http://smallbusiness.yahoo.com/domains]web address for just $1.99/1st yr[/url]. We'll help. [url=http://us.rd.yahoo.com/evt=41244/*http://smallbusiness.yahoo.com/][/url] 	  Quote: 	
		  

ntribution

Dave Pelletier

Joined: 10 Jan 2006
Posts: 100
Location: Prescott, Arizona

Posted: Wed Sep 27, 2006 6:54 am Post subject: Flutter Question

Dennis,



    You've got enough responses to your question without me adding two 

cents.  But I'm addressing the shrotened countrerbalance weights.  I had the 

same problem on my Firestar - too long to get into the trailer.  You can 

drill holes to mount the weights in the "correct" length, then when you're 

getting ready to store the plane in the trailer, remove the bolts, drop the 

rods down to where they are now and temporarily re-bolt them.  That's what I 

did with my Firestar.  You only have to remove and replace two bolts so it's 

not like a major job.



AzDave



 	  Quote: 	
		   My plane IS equipped with the aileron counterbalance rods (thanks again,

 J.Hauck), but they are slightly shortened to accommodate wing folding.



 Dennis Kirby

 Cedar Crest, NM

_________________
AzDave

Steven Green

Joined: 05 Feb 2006
Posts: 118

Posted: Wed Sep 27, 2006 4:03 pm Post subject: Flutter Question

Dennis,



You didn't mention feeling the flutter on the stick.  Before I installed

counter balances on my MK3 I encountered flutter at about 85 mph and it was

very evident in the stick.



A vibration in the airframe can come from a miss in the engine.  My first

and only experience with carb ice on the 912 caused a couple of short bursts

of vibration due to the engine missing as the ice broke loose.  This

happened twice in about a 15 minute period.



Steven



Subject: Flutter Question

 	  Quote: 	
		   

<Dennis.Kirby(at)kirtland.af.mil>
	


 	  Quote: 	
		  

 Kolb Friends -



 I suspect I've had my first encounter with flutter on my Mark-3.

 Not sure - that's why I'm asking this question: Can aileron flutter

 happen in short bursts (like, durations less than one second)?



 I was flying this morning in mildly turbulent air.  Cruise power,

 straight & level at about 65 mph indicated.  I encountered a sudden

 burst of vibration in the airframe that felt like (if you can picture

 this) someone threw a big glop of oatmeal thru the prop.  Just one short

 burst - not a continuous vibration.  At first I thought something soft

 went thru my prop, like a rag or something.



 Lemme tell you - this is something that will make you sit bolt upright,

 eyes wide, and make you wonder, "What the heck was THAT?"



 My plane IS equipped with the aileron counterbalance rods (thanks again,

 J.Hauck), but they are slightly shortened to accommodate wing folding.



 This happened four different times in my 1.2 hour flight.  Aside from

 that, everything was working fine (engine), and my postflight inspection

 revealed no anomalies.  Except ...



 I had repaired some fabric on the outboard trailing edge of the right

 aileron a week before this flight.  In doing so, the outboard six inches

 of aileron gap seal fabric (I use bookbinding tape) was removed.  And

 not re-installed, after the fabric fix.  I suspect the new airflow

 pattern due to the missing tape, plus the extra weight of the fabric

 patch/paint on the aileron, was enough to initiate the flutter.



 Anybody think this could be the cause?



 I will definitely reinstall the gap seal tape before next flight - see

 if that cures the problem.



 Dennis Kirby

 Cedar Crest, NM

_________________
Steven Green

Dennis.Kirby(at)kirtland.
Guest

Posted: Thu Sep 28, 2006 9:00 am Post subject: Flutter Question

<< You say the counter balances were shortened. Are they still in

balance? Installing them and doing a careful balance has the flutter

threshold beyond 120 mph, now.  Rick G >>



Rick -



My counterbalance rods are about 2 inches shorter from the 100% balanced

length.  That would still yield at least 80% balanced - way better than

nothing, but ... maybe not enough.



Your Kolb can go 120?  WOW - Impressive!

At WOT, my Mark-III does somewhere between 70 and 75.



Dennis Kirby

planecrazydld(at)yahoo.co
Guest

Posted: Thu Sep 28, 2006 11:18 am Post subject: Flutter Question

Dave Downey

 in SE PA

 Carpe Tigercubium

  	  	 		Get your own [url= http://us.rd.yahoo.com/evt=43290/*http://smallbusiness.yahoo.com/domains]web address for just $1.99/1st yr[/url]. We'll help.

planecrazzzy
Guest

Posted: Thu Sep 28, 2006 1:47 pm Post subject: Re: Flutter Question

Hey Guys,

               I didn't like the way the counter balancers "stuck out" when the ailerons were in the folded position .... So I made a cross brace to hold them pointing straight up.... ( and I tow it with an OPEN trailer )

 I put a rope on it and a red flag with bugie to the tail wheel...



 Aslo I didn't like how they rubbed on the tail when folded...



   Here's a picture of the simple brace that I made...



 Gotta Fly...

Mike & "Jaz" in MN

.

.

.

 	  Dave Pelletier wrote: 	
		  Dennis,



    You've got enough responses to your question without me adding two 

cents.  But I'm addressing the shrotened countrerbalance weights.  I had the 

same problem on my Firestar - too long to get into the trailer.  You can 

drill holes to mount the weights in the "correct" length, then when you're 

getting ready to store the plane in the trailer, remove the bolts, drop the 

rods down to where they are now and temporarily re-bolt them.  That's what I 

did with my Firestar.  You only have to remove and replace two bolts so it's 

not like a major job.



AzDave



 	  Quote: 	
		   My plane IS equipped with the aileron counterbalance rods (thanks again,

 J.Hauck), but they are slightly shortened to accommodate wing folding.



 Dennis Kirby

 Cedar Crest, NM

Aileron support tube.jpg

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Aileron support.jpg

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It just slips into the same tube as the counter balance rod...

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jindoguy(at)gmail.com
Guest

Posted: Thu Sep 28, 2006 6:54 pm Post subject: Flutter Question

Yours will probably go that fast if you point it down enough. I don't recommend it and I only did it once. It did satisfy me that I don't need to worry about flutter of the ailerons anymore.

It's a shame you didn't get a look at the ailerons when you felt what you thought was flutter. If I can ever find the short scrap of flim my buddy took of the second incident, i'll post it. 



Rick

On 9/28/06, Kirby Dennis Contr MDA/AL <Dennis.Kirby(at)kirtland.af.mil (Dennis.Kirby(at)kirtland.af.mil)> wrote:[quote] --> Kolb-List message posted by: "Kirby Dennis Contr MDA/AL" <Dennis.Kirby(at)kirtland.af.mil (Dennis.Kirby(at)kirtland.af.mil)>



<< You say the counter balances were shortened. Are they still in 

balance? Installing them and doing a careful balance has the flutter

threshold beyond 120 mph, now.  Rick G >>



Rick -



My counterbalance rods are about 2 inches shorter from the 100% balanced

 length.  That would still yield at least 80% balanced - way better than

nothing, but ... maybe not enough.



Your Kolb can go 120?  WOW - Impressive!

At WOT, my Mark-III does somewhere between 70 and 75.



 

-- 

Rick Girard

"Ya'll drop on in"

takes on a whole new meaning

when you live at the airport.  [quote][b]

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