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Flutter (Non-Zenith)

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jmaynard

Joined: 27 Feb 2008
Posts: 394
Location: Fairmont, MN (FRM)

Posted: Mon Aug 11, 2008 6:17 am Post subject: Flutter (Non-Zenith)

On Mon, Aug 11, 2008 at 07:00:26AM -0700, Gig Giacona wrote:

 	  Quote: 	
		   Since there has been so much talk about flutter and there may be builders

 here who don't 100% know what it is I thought I'd post this video.

 

 http://www.dfrc.nasa.gov/Gallery/Movie/PA-30/640x/EM-0098-01.mov


	


A quick Google turned up two NTSB reports for that tail number. One was from

the day of the video. The aircraft landed safely after the flutter incident,

but suffered an overload failure of the stabilator (duh!). It was apparently

repaired and flew for 32 more years, as the other report was from a fatal

accident on December 1, 1998: it was destroyed, killing the pilot, in a fuel

exhaustion accident in West Virginia.

-- 

Jay Maynard, K5ZC                   http://www.conmicro.com

http://jmaynard.livejournal.com      http://www.tronguy.net

Fairmont, MN (FRM)                        (Yes, that's me!)

AMD Zodiac CH601XLi N55ZC (got it!)

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

amyvega2005(at)earthlink.
Guest

Posted: Mon Aug 11, 2008 7:37 am Post subject: Flutter (Non-Zenith)

That accident was not caused by Aileron flutter, but more a structural flutter on the entire  Horiz Stab design.  Apples and Oranges.  So far (From my mouth to Gods' ear) they have not seen a 601 full wing flutter, but a control surface flutter, and that pointed to way loose  cables.  But still no proof it cause any of the accidents.



Juan



--

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Mon Aug 11, 2008 7:44 am Post subject: Re: Flutter (Non-Zenith)

Juan,  Do you have a video of control flutter you can post? If so please do.



DO NOT ARCHIVE



 	  amyvega2005(at)earthlink. wrote: 	
		  That accident was not caused by Aileron flutter, but more a structural flutter on the entire  Horiz Stab design.  Apples and Oranges.  So far (From my mouth to Gods' ear) they have not seen a 601 full wing flutter, but a control surface flutter, and that pointed to way loose  cables.  But still no proof it cause any of the accidents.



Juan



--

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

jmaynard

Joined: 27 Feb 2008
Posts: 394
Location: Fairmont, MN (FRM)

Posted: Mon Aug 11, 2008 8:20 am Post subject: Flutter (Non-Zenith)

On Mon, Aug 11, 2008 at 11:37:25AM -0400, Juan Vega wrote:

 	  Quote: 	
		   That accident was not caused by Aileron flutter, but more a structural

 flutter on the entire Horiz Stab design.


	


Neither Gig nor I said it was. I'm not going to speak for Gig, but I thought

it was a great demonstration of just what flutter - which we've all been

talking about for months now - really is. That's all.



FWIW, I now reach behind the seat and twang the aileron cables during

preflight...

-- 

Jay Maynard, K5ZC                   http://www.conmicro.com

http://jmaynard.livejournal.com      http://www.tronguy.net

Fairmont, MN (FRM)                        (Yes, that's me!)

AMD Zodiac CH601XLi N55ZC (got it!)

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

amyvega2005(at)earthlink.
Guest

Posted: Mon Aug 11, 2008 11:52 am Post subject: Flutter (Non-Zenith)

Agreed, and understand.   Hope you are enjoying the flying in your plane. Hope you are wearing something cooler than the Tron suit.



Juan



--

jmaynard

Joined: 27 Feb 2008
Posts: 394
Location: Fairmont, MN (FRM)

Posted: Mon Aug 11, 2008 12:15 pm Post subject: Flutter (Non-Zenith)

On Mon, Aug 11, 2008 at 03:49:27PM -0400, Juan Vega wrote:

 	  Quote: 	
		   Hope you are enjoying the flying in your plane. Hope you are wearing

 something cooler than the Tron suit.


	


I'm getting a lot of use out of it, and having a lot of fun in the

process...I've put just under 70 hours on it since I took delivery.



The TRON costume is quite cool, actually; spandex is a lousy insulator, so

I'm cold if it's much below 70 degrees. I've flown in it once (for a

newspaper story that should be coming out Wednesday), although I wear a

T-shirt and jeans most of the time.

-- 

Jay Maynard, K5ZC                   http://www.conmicro.com

http://jmaynard.livejournal.com      http://www.tronguy.net

Fairmont, MN (FRM)                        (Yes, that's me!)

AMD Zodiac CH601XLi N55ZC (got it!)

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

hills(at)sunflower.com
Guest

Posted: Mon Aug 11, 2008 4:28 pm Post subject: Flutter (Non-Zenith)

Howdy all;



The tail looked like it might have an adjustable horizontal stabilizer, used

to trim the plane via jack screw, and now it is flexing as it's not really

attached very well to the fuse.  Am I seeing things?



Roger



--

amyvega2005(at)earthlink.
Guest

Posted: Mon Aug 11, 2008 6:37 pm Post subject: Flutter (Non-Zenith)

frade not man, if you find one I'd love to see it as well.



JUan



--

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Tue Aug 12, 2008 5:57 am Post subject: Re: Flutter (Non-Zenith)

Maybe, maybe not. There was to my knowledge no AD issued for this issue and seeing as those were NASA tests I'd think there would be if it were a design issue. Note that the entire horizontal stabilizer is undulating. It says something for the Piper design that it didn't just come apart. 



Also not that the undulation was even transmitted into the rear fuselage skins and they are oil canning.



I didn't really post this video so we could do an after action report on it. I posted it because while there has been a lot of talk about flutter most of us has never actually seen it in action and knowing what to look for is at least part of properly reporting and dealing with a problem.



 	  hills(at)sunflower.com wrote: 	
		  Howdy all;



The tail looked like it might have an adjustable horizontal stabilizer, used

to trim the plane via jack screw, and now it is flexing as it's not really

attached very well to the fuse.  Am I seeing things?



Roger



--

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

d.goddard(at)ns.sympatico
Guest

Posted: Tue Aug 12, 2008 8:36 am Post subject: Flutter (Non-Zenith)

It would have been nice to see a timestamp on it, it looked slowed down and 

I expect we are actually looking at a much shorter period than the 15 

seconds or so that the video runs.

---

planes_by_ken(at)bellsout
Guest

Posted: Tue Aug 12, 2008 9:42 am Post subject: Flutter (Non-Zenith)

A Twin Comanche has a stabalator - all flying horizontal stabilizer.  

Like the Zenith rudder.  There are 2 bolts in bearings at the center for 

the stab to pivot on.  There is a jackscrew to set the trim tab 

position.  The trim tab is of the anti-servo type - it adds to the force 

to move the surface in addition to providing trim.  There is a 

significant counter balance weight on a tube in the fuselage.  The 

weight must be close to 10 lb.  The tube is about 24" long.  The cables 

attach to the tube.  Maintenance items to watch for:  bolts or bearings 

loose at center pivot, loose tab hinges and excess play in the trim 

jackscrew system.  Notice that the tab lags the stab movement.  This 

causes feedback that increases the flutter.

Ken Lilja



Roger & Lina Hill wrote:

 	  Quote: 	
		   



 Howdy all;



 The tail looked like it might have an adjustable horizontal stabilizer, used

 to trim the plane via jack screw, and now it is flexing as it's not really

 attached very well to the fuse.  Am I seeing things?



 Roger

planes_by_ken(at)bellsout
Guest

Posted: Tue Aug 12, 2008 9:54 am Post subject: Flutter (Non-Zenith)

I need to amend this.  The Piper Cherokee series uses the bearings and 

bolts.  The Twin Comanche stab pivots on a tube that is about 2" in 

diameter.

Ken



Ken Lilja wrote:

 	  Quote: 	
		   

 <planes_by_ken(at)bellsouth.net>



 A Twin Comanche has a stabalator - all flying horizontal stabilizer.  

 Like the Zenith rudder.  There are 2 bolts in bearings at the center 

 for the stab to pivot on.  There is a jackscrew to set the trim tab 

 position.  The trim tab is of the anti-servo type - it adds to the 

 force to move the surface in addition to providing trim.  There is a 

 significant counter balance weight on a tube in the fuselage.  The 

 weight must be close to 10 lb.  The tube is about 24" long.  The 

 cables attach to the tube.  Maintenance items to watch for:  bolts or 

 bearings loose at center pivot, loose tab hinges and excess play in 

 the trim jackscrew system.  Notice that the tab lags the stab 

 movement.  This causes feedback that increases the flutter.

 Ken Lilja

hills(at)sunflower.com
Guest

Posted: Tue Aug 12, 2008 5:39 pm Post subject: Flutter (Non-Zenith)

"Notice that the tab lags the stab movement.  This 

causes feedback that increases the flutter". - ok Ken, important safety tip.

Remind me never to fly in a Twin Comanche,,,yikesss

--

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