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kkinney

Joined: 11 Jan 2006
Posts: 42

Posted: Tue Jun 16, 2009 5:03 am Post subject: ZBAG, a respectful question

My question is directed to anyone who has design questions regarding the 601XL.  



What evidence would it take to prove to you the 601XL is free of flutter?



Regards,

Kevin Kinney

jmaynard

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

Posted: Tue Jun 16, 2009 5:22 am Post subject: ZBAG, a respectful question

On Tue, Jun 16, 2009 at 06:03:50AM -0700, kkinney wrote:

 	  Quote: 	
		   My question is directed to anyone who has design questions regarding the

 601XL.

 

 What evidence would it take to prove to you the 601XL is free of flutter?


	


As far as I'm concerned, it's been proven.



That's only one aspect of the design, however. It would take similar studies

of the Zodiac's structure, not just sandbags piled on the wing, but a

complete evaluation of the design from a structural viewpoint, both static

and dynamic, with fully published results, to resolve my concern that

there's a problem somewhere.



Zenair has finally started to do the right thing. They should finish the

job.

-- 

Jay Maynard, K5ZC, PP-ASEL, CFI-SP   http://www.conmicro.com

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

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

AMD Zodiac CH601XLi N55ZC http://www.tronguy.net/N55ZC.shtml

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

ernieth(at)gmail.com
Guest

Posted: Tue Jun 16, 2009 5:42 am Post subject: ZBAG, a respectful question

No aircraft made is flutter free. The GVT test show it is a solid design.. KEEP BUILDING 



On Tue, Jun 16, 2009 at 9:17 AM, Jay Maynard <jmaynard(at)conmicro.com (jmaynard(at)conmicro.com)> wrote:

 [quote]--> Zenith-List message posted by: Jay Maynard <jmaynard(at)conmicro.com (jmaynard(at)conmicro.com)>

  

 On Tue, Jun 16, 2009 at 06:03:50AM -0700, kkinney wrote:

 > My question is directed to anyone who has design questions regarding the

 > 601XL.

 >

 > What evidence would it take to prove to you the 601XL is free of flutter?

 

 

As far as I'm concerned, it's been proven.

 

 That's only one aspect of the design, however. It would take similar studies

 of the Zodiac's structure, not just sandbags piled on the wing, but a

 complete evaluation of the design from a structural viewpoint, both static

 and dynamic, with fully published results, to resolve my concern that

 there's a problem somewhere.

 

 Zenair has finally started to do the right thing. They should finish the

 job.

 --

 Jay Maynard, K5ZC, PP-ASEL, CFI-SP   http://www.conmicro.com

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

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

 AMD Zodiac CH601XLi N55ZC http://www.tronguy.net/N55ZC.shtml

 



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  target="_blank">http://www.matronics.com/Navigator?Zenith-List

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

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[b]

psm(at)att.net
Guest

Posted: Tue Jun 16, 2009 7:01 am Post subject: ZBAG, a respectful question

Hi Kevin,



I believe the XL is free of flutter problems.  The German testing 

confirms that notion.



Alas, that says exactly nothing about the safety of the XL 

design.  It merely confirms that aileron flutter is not the cause of 

all the fatal events with this unfortunate design.



Paul

XL grounded

do not archive

At 06:03 AM 6/16/2009, you wrote:

 	  Quote: 	
		  -> Zenith-List message posted by: "kkinney" <kkinney(at)fuse.net>



My question is directed to anyone who has design questions regarding 

the 601XL.



What evidence would it take to prove to you the 601XL is free of flutter?



Regards,

Kevin Kinney

d.goddard(at)ns.sympatico
Guest

Posted: Tue Jun 16, 2009 7:10 am Post subject: ZBAG, a respectful question

No aircraft, ever, none... Wow! Kinda puts all  those idiot engineers in their place. Glad we're going to solve the potential by  ignoring it. Thanks Ernie. 

 [quote]   ---

jmaynard

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

Posted: Tue Jun 16, 2009 7:34 am Post subject: ZBAG, a respectful question

On Tue, Jun 16, 2009 at 07:58:15AM -0700, Paul Mulwitz wrote:

 	  Quote: 	
		   I believe the XL is free of flutter problems.  The German testing confirms 

 that notion.



 Alas, that says exactly nothing about the safety of the XL design.


	


I disagree: saying that the aircraft is not susceptible to aileron flutter

with tension on the cables is a significant statement about its safety. It

just doesn't say *everything* that needs to be said about it.



 	  Quote: 	
		   It merely confirms that aileron flutter is not the cause of all the fatal

 events with this unfortunate design.


	


That's a little strong. The design is, overall, quite sound. That there may

be an unrevealed flaw (the jury is very much still out on that one) does not

mean that it's "unfortunate".

-- 

Jay Maynard, K5ZC, PP-ASEL, CFI-SP   http://www.conmicro.com

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

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

AMD Zodiac CH601XLi N55ZC http://www.tronguy.net/N55ZC.shtml

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

daveaustin2(at)primus.ca
Guest

Posted: Tue Jun 16, 2009 8:43 am Post subject: ZBAG, a respectful question

I used to work for Canadair, back in the days when they were building the 

F86 and the Argus subhunter.

They used the sandbag technique for load testing.  Should they have gone 

further?

Dave Austin  601HDS - 912

jmaynard

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

Posted: Tue Jun 16, 2009 9:44 am Post subject: ZBAG, a respectful question

On Tue, Jun 16, 2009 at 12:39:51PM -0400, Dave Austin wrote:

 	  Quote: 	
		   I used to work for Canadair, back in the days when they were building the 

 F86 and the Argus subhunter.

 They used the sandbag technique for load testing.  Should they have gone 

 further?


	


In those days, they didn't have the advanced numerical analysis tools

available to aeronautical engineers now. They also tested to destruction.

Zenair has, to the best of my knowledge (which may be incorrect), done

neither until the GVT-supported flutter analysis.

-- 

Jay Maynard, K5ZC, PP-ASEL, CFI-SP   http://www.conmicro.com

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

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

AMD Zodiac CH601XLi N55ZC http://www.tronguy.net/N55ZC.shtml

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

ernieth(at)gmail.com
Guest

Posted: Tue Jun 16, 2009 10:11 am Post subject: ZBAG, a respectful question

Dave

sorry i hurt your feelings. 

Even the NTSB said something like flutter mitigation, not flutter free. If it was the keep build comment that hurt your feelings, I think it is the right thing to do it is not ignoring anything

 



E.



On Tue, Jun 16, 2009 at 11:09 AM, Dave <d.goddard(at)ns.sympatico.ca (d.goddard(at)ns.sympatico.ca)> wrote:

[quote]        No aircraft, ever, none... Wow! Kinda puts all  those idiot engineers in their place. Glad we're going to solve the potential by  ignoring it. Thanks Ernie. 

 [quote]   ---

William Dominguez

Joined: 09 Apr 2008
Posts: 118

Posted: Tue Jun 16, 2009 10:51 am Post subject: ZBAG, a respectful question

What evidence would it take to prove to you the 601XL is free of flutter?



For me the most important thing is not to find evidence that the Zodiac is flutter free or flutter prone. The most important thing is to find a solution that will avoid this type of accident in the future. The evidence will be in the record, when this type of accident rate have come down to normal level compared to similar designs, that will be evidence that the problem was resolved. If they keep happening at same or higher rate, it will be evidence that we still have a problem.



Having said that, I don't accept that the plane is a dangerous one. If my plane would be ready today I would fly it. The structural failure rate for the XL is less than 2 percent of the fleet. Higher than other similar designs but not high enough to be considered dangerous. After all, most pilot  flying XLs today have a higher risk of getting a stroke or a heart attack than getting a wing folded during flight. Of course, this is assuming that they fly as intended.



William Dominguez

Zodiac 601XL Plans

Miami Florida

http://www.geocities.com/bill_dom



--- On Tue, 6/16/09, kkinney <kkinney(at)fuse.net> wrote:

 	  Quote: 	
		  

From: kkinney <kkinney(at)fuse.net>

Subject: Zenith-List: ZBAG, a respectful question

To: zenith-list(at)matronics.com

Date: Tuesday, June 16, 2009, 9:03 AM



--> Zenith-List message posted by: "kkinney" <[url=/mc/compose?to=kkinney(at)fuse.net]kkinney(at)fuse.net[/url]>



My question is directed to anyone who has design questions regarding the 601XL.  



What evidence would it take to prove to you the 601XL is  free of flutter?



Regards,

Kevin Kinney





Read this topic online here:



http://forums.matronics.com/vihref="http://www.matronics.com/Navigator?Zenith-List" target="_blank">hsp;  - MATRONICS WEB FORUMS ;               -Matt Dralle, List Admin==========





	
  [quote][b]

_________________
William Dominguez
Zodiac 601XL Plans
Miami Florida
http://www.geocities.com/bill_dom

d.goddard(at)ns.sympatico
Guest

Posted: Tue Jun 16, 2009 12:22 pm Post subject: ZBAG, a respectful question

Not to worry, feelings intact. I just find absolute  declarations of a defect or the lack thereof are not helpful. I have never  experienced flutter in anything so the absolute declaration of no aircraft being  free to be a little odd. I suppose it could happen, but then there's be all that  s**t to clean up. 

 [quote]   ---

ernieth(at)gmail.com
Guest

Posted: Tue Jun 16, 2009 12:50 pm Post subject: ZBAG, a respectful question

Dave,Sorry that you do like absolute declarations. I have not been on a bridge that has fallen down but I know ALL bridges will.

E



On Tue, Jun 16, 2009 at 3:58 PM, Dave <d.goddard(at)ns.sympatico.ca (d.goddard(at)ns.sympatico.ca)> wrote:

 [quote]       Not to worry, feelings intact. I just find absolute  declarations of a defect or the lack thereof are not helpful. I have never  experienced flutter in anything so the absolute declaration of no aircraft being  free to be a little odd. I suppose it could happen, but then there's be all that  s**t to clean up. 

 [quote]   ---

d.goddard(at)ns.sympatico
Guest

Posted: Tue Jun 16, 2009 1:12 pm Post subject: ZBAG, a respectful question

Different perceptions I suppose. I expect  it may be possible for any single one to fall, I would expect that  most are actually retired and dismantled first. So an absolute declaration  that they all in fact will, appears to be mistaken. 

  

 [quote]   ---

ernieth(at)gmail.com
Guest

Posted: Tue Jun 16, 2009 1:25 pm Post subject: ZBAG, a respectful question

Dave,



I think all Suspension bridges have a flutter in them under the right wind loads, maybe the civil engineers in the crowd will know better, there is this case.

 http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge

 



e

 

On Tue, Jun 16, 2009 at 5:11 PM, Dave <d.goddard(at)ns.sympatico.ca (d.goddard(at)ns.sympatico.ca)> wrote:

[quote]        Different perceptions I suppose. I expect  it may be possible for any single one to fall, I would expect that  most are actually retired and dismantled first. So an absolute declaration  that they all in fact will, appears to be mistaken. 

  

 [quote]   ---

ernieth(at)gmail.com
Guest

Posted: Tue Jun 16, 2009 1:38 pm Post subject: ZBAG, a respectful question

Sorrywrong link

[url=http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)]http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)[/url]

e



On Tue, Jun 16, 2009 at 5:24 PM, ernie <ernieth(at)gmail.com (ernieth(at)gmail.com)> wrote:

 [quote]Dave,



I think all Suspension bridges have a flutter in them under the right wind loads, maybe the civil engineers in the crowd will know better, there is this case.

  http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge

  



e

 

 

On Tue, Jun 16, 2009 at 5:11 PM, Dave <d.goddard(at)ns.sympatico.ca (d.goddard(at)ns.sympatico.ca)> wrote:

[quote]         Different perceptions I suppose. I expect  it may be possible for any single one to fall, I would expect that  most are actually retired and dismantled first. So an absolute declaration  that they all in fact will, appears to be mistaken. 

  

 [quote]   ---

z601(at)anemicaardvark.co
Guest

Posted: Tue Jun 16, 2009 3:09 pm Post subject: ZBAG, a respectful question

On Tuesday 16 June 2009 16:24, ernie wrote:

 	  Quote: 	
		   Dave,

 I think all Suspension bridges have a flutter in them under the right wind

 loads, maybe the civil engineers in the crowd will know better, there

 is this case.

 http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge


	


I'm not a civil engineer, but I was trained as a physicist. The Tacoma Narrows 

Bridge collapse was drilled into us as an example of physical resonance. I 

don't think you can  get flutter without having resonance, be it in a bridge, 

or whatever. 



The resonance needs a sharp peak at some frequency to get a good oscillation 

going. Without the resonance and sharp peak, no oscillation.



I believe I was told that it is possible to minimize the potential for 

resonance at the design level, and test for it with a process similar to 

ground vibration testing. As far as I know, there are indeed suspension 

bridges which do not oscillate, and do not have flutter.



The ground vibration testing performed on the 601XL would indicate the 

aircraft wings do not have a resonance point with a significant peak. Thus, 

for most practical purposes, it is extremely unlikely flutter will develop. I 

think most aircraft designers and structrual dynamicists would probably take 

that position.



This is not to say that there either is, or is not, some other design problem. 

I personally am comfortable that the aircraft is reasonably well designed, 

and have every intention of flying it when completed. Whether someone else 

feels comfortable with flying their 601XL seems to me to be a personal 

decision.

==============================================

   You can check on my aircraft construction     

progress at: http://www.mykitlog.com/santaigo

=================================================

               Jim B. Belcher

    BS, MS Physics, math, Computer Science

                  A&P/IA

           Instrument Rated Pilot

     General Radio Telephone Certificate

     Retired Aerospace Technical Manager

=================================================

ernieth(at)gmail.com
Guest

Posted: Tue Jun 16, 2009 3:40 pm Post subject: ZBAG, a respectful question

Thank you Jim.

I think I am being misunderstood. Remember  my first post "The GVT test show it is a solid design.. KEEP BUILDING ."

Every structure has a resonance frequency. Flutter that I am talking about does not have to be destructive, and may be out of the normal operating range. Even with extra Damping will also take a number of oscillation to damping out. 

http://en.wikipedia.org/wiki/Aeroelasticity#Flutter   At its mildest this can appear as a "buzz" 

Sorry I even started typing on this list.

E

On Tue, Jun 16, 2009 at 7:11 PM, Jim Belcher <z601(at)anemicaardvark.com (z601(at)anemicaardvark.com)> wrote:

[quote] --> Zenith-List message posted by: Jim Belcher <z601(at)anemicaardvark.com (z601(at)anemicaardvark.com)>

 On Tuesday 16 June 2009 16:24, ernie wrote:

 > Dave,

 > I think all Suspension bridges have a flutter in them under the right wind

 > loads, maybe the civil engineers in the crowd will know better, there

 > is this case.

 > http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge

I'm not a civil engineer, but I was trained as a physicist. The Tacoma Narrows

 Bridge collapse was drilled into us as an example of physical resonance. I

 don't think you can  get flutter without having resonance, be it in a bridge,

 or whatever.

 The resonance needs a sharp peak at some frequency to get a good oscillation

 going. Without the resonance and sharp peak, no oscillation.

 I believe I was told that it is possible to minimize the potential for

 resonance at the design level, and test for it with a process similar to

 ground vibration testing. As far as I know, there are indeed suspension

 bridges which do not oscillate, and do not have flutter.

 The ground vibration testing performed on the 601XL would indicate the

 aircraft wings do not have a resonance point with a significant peak. Thus,

 for most practical purposes, it is extremely unlikely flutter will develop. I

 think most aircraft designers and structrual dynamicists would probably take

 that position.

 This is not to say that there either is, or is not, some other design problem.

 I personally am comfortable that the aircraft is reasonably well designed,

 and have every intention of flying it when completed. Whether someone else

 feels comfortable with flying their 601XL seems to me to be a personal

 decision.

 =====================

    You can check on my aircraft construction

 progress at: http://www.mykitlog.com/santaigo

 ========================

                Jim B. Belcher

     BS, MS Physics, math, Computer Science

                   A&P/IA

            Instrument Rated Pilot

      General Radio Telephone Certificate

      Retired Aerospace Technical Manager

 ========================

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  target="_blank">http://www.matronics.com/Navigator?Zenith-List

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ===========

[b]

d.goddard(at)ns.sympatico
Guest

Posted: Tue Jun 16, 2009 4:06 pm Post subject: ZBAG, a respectful question

Ernie, don't be sorry and please don't stop  participating. Different people, different perceptions and ideas. In most places  where exchange can take place it's a good thing. My response to you was not  meant as a challenge, just wanted to point out that and "all planes" statement  was perhaps beyond the scope of acceptable known facts. I also feel it is likely  that "every structure" may not have a resonant frequency. I don't claim to know  this, it simply seems unlikely. 

  

  

   [quote][b]

ernieth(at)gmail.com
Guest

Posted: Tue Jun 16, 2009 5:35 pm Post subject: ZBAG, a respectful question

Ok,Maybe not every structure, but with the GVT testing the 601 designs natural resonant frequency has been found to be dampened and not going to cause issues in a normal operating environment.

E  



 On Tue, Jun 16, 2009 at 8:06 PM, Dave <d.goddard(at)ns.sympatico.ca (d.goddard(at)ns.sympatico.ca)> wrote:

[quote]        Ernie, don't be sorry and please don't stop  participating. Different people, different perceptions and ideas. In most places  where exchange can take place it's a good thing. My response to you was not  meant as a challenge, just wanted to point out that and "all planes" statement  was perhaps beyond the scope of acceptable known facts. I also feel it is likely  that "every structure" may not have a resonant frequency. I don't claim to know  this, it simply seems unlikely. 

  

  

    	  Quote: 	
		  



arget="_blank">http://www.matronics.com/Navigator?Zenith-List

tp://forums.matronics.com

_blank">http://www.matronics.com/contribution



	




[b]

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Tue Jun 16, 2009 7:17 pm Post subject: ZBAG, a respectful question

Off Topic.



Nope. That's why suspension bridges have the steel gratings down the  

center. The gratings kill the lift that would be generated in high  

wind conditions. The first Tacoma Narrows bridge had a solid road bed  

with no gratings. It was also designed too thin and flexible.  

Engineers learned a lot from the mistakes made at Tacoma Narrows.  

Modern suspension bridges absolutely will not react like the first  

Tacoma Narrows bridge did, even under the strongest winds.



On Jun 16, 2009, at 5:24 PM, ernie wrote:



 	  Quote: 	
		   Dave,



 I think all Suspension bridges have a flutter in them under the  

 right wind loads, maybe the civil engineers in the crowd will know  

 better, there is this case.

 http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge




	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

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