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601 problems
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planecrazydld(at)yahoo.co
Guest

Posted: Wed Dec 24, 2008 5:50 pm Post subject: 601 problems

unfortunately the loads resolve structurally without regard to the lifting...



A vertical shear web through the wing allows a zero sweep wing. That is a very major modification to the XL.



David L. Downey

  Harleysville (SE) PA, USA



  

--- On Wed, 12/24/08, Geoff Eather <geather(at)bigpond.net.au> wrote:

[quote]From: Geoff Eather <geather(at)bigpond.net.au>

Subject: RE: Re: 601 problems

To: zenith601-list(at)matronics.com

Date: Wednesday, December 24, 2008, 4:50 PM



                       

Paul   

     

Doesn’t wing sweep depend on the angle of the front spar? If you make the front spar vertical (by lifting the front wheel) then the sweep magically “disappears”!! – see pics   

     

ge   

     

     

           

  

From: owner-zenith601-list-server(at)matronics.com [mailto:owner-zenith601-list-server(at)matronics.com] On Behalf Of paulrod36(at)msn.com

 Sent: 25 December, 2008 7:45 AM

 To: zenith601-list(at)matronics.com

 Subject: Re: Zenith601-List: Re: 601 problems   

  

         

You're not the only one..I've been putting the wings in place as a rough draft to figure out where the holes for cables, fuel lines and wires go, and once I get the temporary pins in, I see forward sweep. Not a whole lot, but it's there, and it's driving me nuts. With what we know about the spars and carry-through all being individually mated during manufacture, my original skepticism about sweep has turned to wonderment and consternation. If I pivot the wings back to the neutral position, I'm putting a load on the spar-to-carry-through joint, where ideally there shouldn't be any. Anybody got any ideas on this?   

    

    

    

Paul Rodriguez   

  [quote]    

---

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planecrazydld(at)yahoo.co
Guest

Posted: Wed Dec 24, 2008 5:52 pm Post subject: 601 problems

do you guys understand that lift and drag induced bending only see the structural sweep?



David L. Downey

  Harleysville (SE) PA, USA



  

--- On Wed, 12/24/08, Bryan Martin <bryanmmartin(at)comcast.net> wrote:

[quote]From: Bryan Martin <bryanmmartin(at)comcast.net>

Subject: Re: Re: 601 problems

To: zenith601-list(at)matronics.com

Date: Wednesday, December 24, 2008, 6:55 PM



[quote]--> Zenith601-List message posted by: Bryan Martin

<bryanmmartin(at)comcast.net>



The forward sweep is an artifact of the 3 degree forward tilt of the spar and

the wing dihedral. If you raise the nose until the spar is vertical you will see

no forward sweep. During final  assembly, the entire spar web should be on the

same plane with no bend in it.



On Dec 24, 2008, at 3:45 PM, <paulrod36(at)msn.com>

<paulrod36(at)msn.com> wrote:



 	  Quote: 	
		   You're not the only one..I've been putting the wings in place as a

rough draft to figure out where the holes for cables, fuel lines and wires go,
	


and once I get the temporary pins in, I see forward sweep. Not a whole lot, but

it's there, and it's driving me nuts. With what we know about the spars

and carry-through all being individually mated during manufacture, my original

skepticism about sweep has turned to wonderment and consternation. If I pivot

the wings back to the neutral position, I'm putting a load on the

spar-to-carry-through joint, where ideally there shouldn't be any. Anybody

got any ideas on this?

 	  Quote: 	
		   


	


--Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not         [quote][b]

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bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Fri Dec 26, 2008 1:45 pm Post subject: 601 problems

The apperant forward sweep of the XL wing is to small to significantly effect the aerodynamics of the aircraft. A much larger forward sweep is needed to cause any significant effect.  

  



---

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

planecrazydld(at)yahoo.co
Guest

Posted: Fri Dec 26, 2008 4:34 pm Post subject: 601 problems

the FSW is not an aerodynamic concern - it is a structural concern. ALL FSW built/designed from isotropic materials suffer from structural divergence with  bending due to increased AOA at the tip under those conditions. It is not a coincidence that the first "successful" FSW occurred in teh 90 with the advent of tailored structure courtesy of advanced composite materials - very highly anisotropic in nature. Only with those materials is it possible to desing any degree of FSW without a massive weight hit.



The short lived Hansa bizjet is the only fsw comercial design extant. The germans tried during WWII but found that when the structure was befed enough to withstand the divergence issue, it was too heavy to offer any benefit. 



David L. Downey

  Harleysville (SE) PA, USA



  

--- On Fri, 12/26/08,  bryanmmartin(at)comcast.net <bryanmmartin(at)comcast.net> wrote:

[quote]From: bryanmmartin(at)comcast.net <bryanmmartin(at)comcast.net>

Subject: Re: Re: 601 problems

To: zenith601-list(at)matronics.com

Date: Friday, December 26, 2008, 4:44 PM



#yiv960487525 p {margin:0;}

The apperant forward sweep of the XL wing is to small to significantly effect the aerodynamics of the aircraft. A much larger forward sweep is needed to cause any significant effect.  

  



---

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bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Sun Dec 28, 2008 3:12 pm Post subject: 601 problems

It's not any kind of concern for the 601XL. The amount of sweep is not  

significant. All of the FSW aircraft you have mentioned have  

significant forward sweep, on the order of 15 degrees or more, and  

that sweep comes from sweeping the spar forward at an angle to the  

fuselage.



On Dec 26, 2008, at 7:34 PM, David Downey wrote:



 	  Quote: 	
		   the FSW is not an aerodynamic concern - it is a structural concern.  

 ALL FSW built/designed from isotropic materials suffer from  

 structural divergence with  bending due to increased AOA at the tip  

 under those conditions. It is not a coincidence that the first  

 "successful" FSW occurred in teh 90 with the advent of tailored  

 structure courtesy of advanced composite materials - very highly  

 anisotropic in nature. Only with those materials is it possible to  

 desing any degree of FSW without a massive weight hit.



 The short lived Hansa bizjet is the only fsw comercial design  

 extant. The germans tried during WWII but found that when the  

 structure was befed enough to withstand the divergence issue, it was  

 too heavy to offer any benefit.



 David L. Downey

 Harleysville (SE) PA, USA


	




-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

- The Matronics Zenith601-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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

planecrazydld(at)yahoo.co
Guest

Posted: Sun Dec 28, 2008 4:56 pm Post subject: 601 problems

Bryan;



I hear you loud and clear - I am not suggesting that it is a major issue. What I am suggesting is that there is a contributing destabilizing design feature that may come into play only under abuse or repeated abuse.



The reason for angling the spar forward more than the 25% chord line of the wing planform is to attempt to control the structural and aerodynamic dvergence that is the issue with FSW. When aerodynamic loads start to bend the wing, the twisting forces due to the placement of the spars tends to reduce the instantaneous AOA whereas in the case of a spar located on a constant percentage of chord or actually shifting to a greater percent of shord as span increases (the actual situation with the 601XL) and aerodynamic loading prior to stall simply bends the wing to a greater AOA - and greater loading.



I will not post to this  again. I meant no assault - to anyone. Having spent my entire life in the design and testing of airframes and materials, and with that the associated loss of a couple of good friends in flight test accidents,  it bothers me to see a detail glossed over that may be a (perhaps tiny) piece of the puzzle that is the service history of the XL.



David L. Downey

  Harleysville (SE) PA, USA



  

--- On Sun, 12/28/08, Bryan Martin <bryanmmartin(at)comcast.net> wrote:

[quote]From: Bryan Martin <bryanmmartin(at)comcast.net>

Subject: Re: Re: 601 problems

To: zenith601-list(at)matronics.com

Date: Sunday, December 28, 2008, 6:12 PM



[quote]--> Zenith601-List message posted by: Bryan Martin

<bryanmmartin(at)comcast.net>



It's not any kind of concern for the  601XL. The amount of sweep is not

significant. All of the FSW aircraft you have mentioned have significant forward

sweep, on the order of 15 degrees or more, and that sweep comes from sweeping

the spar forward at an angle to the fuselage.



On Dec 26, 2008, at 7:34 PM, David Downey wrote:



 	  Quote: 	
		   the FSW is not an aerodynamic concern - it is a structural concern. ALL

FSW built/designed from isotropic materials suffer from structural divergence
	


with  bending due to increased AOA at the tip under those conditions. It is not

a coincidence that the first "successful" FSW occurred in teh 90 with

the advent of tailored structure courtesy of advanced composite materials - very

highly anisotropic in nature. Only with those materials is it possible to desing

any degree of FSW without a massive weight hit.

[quote] 

 The short lived Hansa bizjet is the only fsw comercial design extant. The

germans tried during WWII but          	  Quote: 	
		  [b]

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planecrazydld(at)yahoo.co
Guest

Posted: Mon Dec 29, 2008 4:21 am Post subject: 601 problems

I had not even thought of that Sabrina. It is definitely possible - might couple to slack control system cabling or yielded brackets...



David L. Downey

  Harleysville (SE) PA, USA



  

--- On Mon, 12/29/08, Sabrina <chicago2paris(at)msn.com> wrote:

 	  Quote: 	
		  From: Sabrina <chicago2paris(at)msn.com>

Subject: Re: 601 problems

To: zenith601-list(at)matronics.com

Date: Monday, December 29, 2008, 12:12 AM



 	  Quote: 	
		  --> Zenith601-List message posted by: "Sabrina"<chicago2paris(at)msn.com>"The forward sweep is an artifact of the 3 degree forward tilt of the sparand the wing dihedral. If you raise the nose until the spar is vertical you willsee no forward

 sweep." Bryan “I will not post to this again. I meant no assault - to anyone.” David  David, you should keep at it. The forward sweep of the wing in cruise attitudechanges the way the air flows over the ailerons.   In otherwords, spanwiseairflow over a forward-swept wing is the reverse of a conventional swept wing. The fact that the sweep is so slight and can change with flight attitude may bean important factor for the LAA and NTSB to consider in determining how and whenthe ailerons that did unzip, unzipped since the airflow across them reverseswhile leveling off after a climb.  Correct?Read this topic online here:http://forums.matronics.com/viewtopic.php?p=221565#221565Attachments: http://forums.matronics.com//=== 	
	


         [quote][b]

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Tim Juhl

Joined: 21 Mar 2006
Posts: 488
Location: "Thumb" of Michigan

Posted: Mon Dec 29, 2008 8:25 am Post subject: Re: 601 problems

Sabrina,

In your recent email you mention "may be an important factor for the LAA and NTSB to consider in determining how and when the ailerons that did unzip, unzipped... "  As I recall, your gussets were developed with this issue in mind.



To your knowledge, is the potential for "unzip" suspected to exist only in aircraft with piano hinge ailerons or in the hingeless type as well?  



Tim

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_________________
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
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