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accident - slanted spar question

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backstagelive(at)gmail.co
Guest

Posted: Thu Mar 13, 2008 9:39 am Post subject: accident - slanted spar question

Friends,



My friend who lives in the area in Austrailia where the accident happened is 

sending me daily updates on the news articles and the feelings of the 

pilots. I haven't been posting it because most of it appears here in the 

forum before I get it so it wouldn't add anything new. John has sent this in 

today's letter:



"They found the wreckage yesterday (weathers been bad winds to strong) and 

hope to bring it up today. I think it might be to do with slanting the spar. 

My brothers a Structural Engineer and says by taking the spar out of 

vertical it opens up a whole new area of column failures which are very hard 

to predict."



That was an interesting statement and I don't remember anyone ever talking 

about the slanting of the spar. I'm not an engineer, but I would love to 

hear from someone who is. Would the slant of the spar make it weaker or more 

dangerous in violent flight?



Count me in also. See you at Sun & Fun.



Joe in Oshkosh - 601 XL



90% finished with 40% left to go

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu Mar 13, 2008 9:58 am Post subject: Re: accident - slanted spar question

I've mentioned it, and I believe Dave Downey has mentioned it too.



I'm also of the opinion that, if you have a wing locker, there's even that much less (if anything really) holding that spar in position in a critical area.



See if you can find out if this XL had a wing locker.



 	  backstagelive(at)gmail.co wrote: 	
		  Friends,



My friend who lives in the area in Austrailia where the accident happened is 

sending me daily updates on the news articles and the feelings of the 

pilots. I haven't been posting it because most of it appears here in the 

forum before I get it so it wouldn't add anything new. John has sent this in 

today's letter:



"They found the wreckage yesterday (weathers been bad winds to strong) and 

hope to bring it up today. I think it might be to do with slanting the spar. 

My brothers a Structural Engineer and says by taking the spar out of 

vertical it opens up a whole new area of column failures which are very hard 

to predict."



That was an interesting statement and I don't remember anyone ever talking 

about the slanting of the spar. I'm not an engineer, but I would love to 

hear from someone who is. Would the slant of the spar make it weaker or more 

dangerous in violent flight?



Count me in also. See you at Sun & Fun.



Joe in Oshkosh - 601 XL



90% finished with 40% left to go

Gig Giacona

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

Posted: Thu Mar 13, 2008 10:17 am Post subject: Re: accident - slanted spar question

Andy, I have to ask. Have you ever seen the wing locker built to Zenith specs in person? I ask because having installed two of them IMHO that part of the wing may have more strength than any place else.

 	  ashontz wrote: 	
		  I'm also of the opinion that, if you have a wing locker, there's even that much less (if anything really) holding that spar in position in a critical area.

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

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu Mar 13, 2008 10:26 am Post subject: Re: accident - slanted spar question

I've looked at it one the plans and in photos. Look at where the resistance stress vectors are pointing back to from the forward canted top edge of the main spar that should be keeping the spar in that area vertical. They point back to an open air right in the middle of the wing.



If someone put a gun to my head and said I HAD to intall a wing locker, my wing locker would be semicicular in shape with the circular side facing forward.



 	  Gig Giacona wrote: 	
		  Andy, I have to ask. Have you ever seen the wing locker built to Zenith specs in person? I ask because having installed two of them IMHO that part of the wing may have more strength than any place else.

 	  ashontz wrote: 	
		  I'm also of the opinion that, if you have a wing locker, there's even that much less (if anything really) holding that spar in position in a critical area.

n85ae

Joined: 14 Mar 2007
Posts: 403

Posted: Thu Mar 13, 2008 10:29 am Post subject: Re: accident - slanted spar question

That absolutely makes sense, and the further aft the center of lift will

shift (from a rapid pullup for example)  the more that would be emphasized.

Which in fact completely explains why the simple sandbag test isn't that good a test. They could try loading the wing inverted at say 30-45 degrees

off level and that would probably fail the wing.



My guess that is.



Jeff



 	  Quote: 	
		  That was an interesting statement and I don't remember anyone ever talking

about the slanting of the spar. I'm not an engineer, but I would love to

hear from someone who is. Would the slant of the spar make it weaker or more

dangerous in violent flight?

Gig Giacona

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

Posted: Thu Mar 13, 2008 10:38 am Post subject: Re: accident - slanted spar question

So Andy your answer to my question is no then?



I know CH's qualifications to make design decisions like the one you make below. Do you mind posting yours?



 	  ashontz wrote: 	
		  I've looked at it one the plans and in photos. Look at where the resistance stress vectors are pointing back to from the forward canted top edge of the main spar that should be keeping the spar in that area vertical. They point back to an open air right in the middle of the wing.



If someone put a gun to my head and said I HAD to intall a wing locker, my wing locker would be semicicular in shape with the circular side facing forward.



 	  Gig Giacona wrote: 	
		  Andy, I have to ask. Have you ever seen the wing locker built to Zenith specs in person? I ask because having installed two of them IMHO that part of the wing may have more strength than any place else.

 	  ashontz wrote: 	
		  I'm also of the opinion that, if you have a wing locker, there's even that much less (if anything really) holding that spar in position in a critical area.

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

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Thu Mar 13, 2008 10:49 am Post subject: Re: accident - slanted spar question

No, I haven't. Want to correct my spelling too?



My qualifications, 4 years of engineering school.



In layman's terms, anyone skilled at origami can tell exactly where that wing would fold first, and it would be at the wing locker.



 	  Gig Giacona wrote: 	
		  So Andy your answer to my question is no then?



I know CH's qualifications to make design decisions like the one you make below. Do you mind posting yours?



 	  ashontz wrote: 	
		  I've looked at it one the plans and in photos. Look at where the resistance stress vectors are pointing back to from the forward canted top edge of the main spar that should be keeping the spar in that area vertical. They point back to an open air right in the middle of the wing.



If someone put a gun to my head and said I HAD to intall a wing locker, my wing locker would be semicicular in shape with the circular side facing forward.



 	  Gig Giacona wrote: 	
		  Andy, I have to ask. Have you ever seen the wing locker built to Zenith specs in person? I ask because having installed two of them IMHO that part of the wing may have more strength than any place else.

 	  ashontz wrote: 	
		  I'm also of the opinion that, if you have a wing locker, there's even that much less (if anything really) holding that spar in position in a critical area.

planecrazydld(at)yahoo.co
Guest

Posted: Thu Mar 13, 2008 11:26 am Post subject: accident - slanted spar question

...but only because pretty much everyone considers me to be a forcaster of falling sky... that, and the associated minor forward sweep is the center of my interest.



Joe Scheibinger <backstagelive(at)gmail.com> wrote:[quote] --> Zenith-List message posted by: "Joe Scheibinger" 



Friends,



My friend who lives in the area in Austrailia where the accident happened is 

sending me daily updates on the news articles and the feelings of the 

pilots. I haven't been posting it because most of it appears here in the 

forum before I get it so it wouldn't add anything new. John has sent this in 

today's letter:



"They found the wreckage yesterday (weathers been bad winds to strong) and 

hope to bring it up today. I think it might be to do with slanting the spar. 

My brothers a Structural Engineer       [quote][b]

Gig Giacona

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

Posted: Thu Mar 13, 2008 12:35 pm Post subject: Re: accident - slanted spar question

No Andy I have no desire to correct your spelling as long as you don't mine me taking my aircraft building advise from someone that has actually trained to and designed several successful aircraft.



For the life of me I can't understand why you are still even considering building, much less, flying a 601.



 	  ashontz wrote: 	
		  No, I haven't. Want to correct my spelling too?



My qualifications, 4 years of engineering school.



In layman's terms, anyone skilled at origami can tell exactly where that wing would fold first, and it would be at the wing locker.

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

MaxNr(at)aol.com
Guest

Posted: Thu Mar 13, 2008 1:27 pm Post subject: accident - slanted spar question

At this time it seems unreasonable for me to degrade the strength of the semi monocoque wing with wing lockers. I think I'll sit back and watch for a while. I'm wondering if it might even help a little, if I installed the structures that go between the ribs, then skin over that area completely. Theoretically, I could later cut out the lockers and install the hardware. Or leave it as is forever, my choice. For now, I will use my Hartwell Latches elsewhere.

 

 Bob 

**************

It's Tax Time! Get tips, forms, and advice on AOL Money & Finance.

      (http://money.aol.com/tax?NCID=aolprf00030000000001)  [quote][b]

Gig Giacona

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

Posted: Thu Mar 13, 2008 2:00 pm Post subject: Re: accident - slanted spar question

This is exactly the problem with this entire conversation. There is exactly zero evidence that the lockers weaken the wings. Nobody has even confirmed that any of the failed airframes had wing lockers. They certainly weren't mentioned in any of the accident reports.

 	  MaxNr(at)aol.com wrote: 	
		  At this time it seems unreasonable for me to degrade the strength of the semi monocoque wing with wing lockers. I think I'll sit back and watch for a while. I'm wondering if it might even help a little, if I installed the structures that go between the ribs, then skin over that area completely. Theoretically, I could later cut out the lockers and install the hardware. Or leave it as is forever, my choice. For now, I will use my Hartwell Latches elsewhere.

 

 Bob

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

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