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sonar1@cox.net

Joined: 02 Oct 2007
Posts: 55
Location: Santa Barbara, Ca

Posted: Mon Mar 17, 2008 12:05 am Post subject: My figures don't compute

I ran some figures on the XL wing attachments and do not get good answers.

 

Can someone who has done statics calculations more recently than my 48 years ago check my work and tell me where I went wrong?



Not trying to revive last weeks discussions on the list - just want to talk to an engineer before I go flying.



Do not archive    ....................Fred Sanford....N9601....98%.......California

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ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Mon Mar 17, 2008 6:12 am Post subject: Re: My figures don't compute

There are six bolts in there. I think you'd need to redo the analysis using the six bolts. I was going to get my Statics textbook out for this one myself, but I don't think this is a problem, albeit, I'd be damn sure to make sure those bolts were drilled right on the money AND reamed which it of course does call for. Even so, the NTSB never mentioned that joint failing. In fact, the folding occurred further outboard. I think that joint is fine, albeit pretty hairy looking at first glance.



A rough calculation around that fixed center virtual pivot would give about 13,577lbs on one bolt, divided by 6 bolts is 2,262lbs, times 6Gs is still only 13,577lbs per bolt.



That joint is fine.



 	  sonar1(at)cox.net wrote: 	
		  I ran some figures on the XL wing attachments and do not get good answers.

 

Can someone who has done statics calculations more recently than my 48 years ago check my work and tell me where I went wrong?



Not trying to revive last weeks discussions on the list - just want to talk to an engineer before I go flying.



Do not archive    ....................Fred Sanford....N9601....98%.......California

moorecomp

Joined: 14 Aug 2006
Posts: 32

Posted: Mon Mar 17, 2008 6:49 am Post subject: Re: My figures don't compute

Fred,



I am an A&P, not an aeronautical engineer, but I did work as a structures engineer (liaison engineer) for a major regional airline.  My boss was a structures DER and I did design structural repairs and computed the substantiation for repairs that required a form 8130.  The simple answer to your calculations, is that we always used the B basis values from the MIL-HDBK-5 (since obsolete).  The value for Ftu is 43ksi, but the Fbru is 90ksi (assuming ed > 2.0).  If you use the ultimate strength in bearing, I get 7.165 g max.  Usually the only time a joint like this is bearing limited, is in very thin materials.  Instead of arbitrarily using lower values, normally a published value is used, and then a margin of safety is applied.  So after you do your calculations, you then have to correct for your margin of safety (typically 1.5 for transport catagory a/c).  Hope this refreshs the memory.



Craig Moore A&P

701 builder wannabe

Mancelona, MI

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Mon Mar 17, 2008 6:53 am Post subject: Re: My figures don't compute

 	  ashontz wrote: 	
		  There are six bolts in there. I think you'd need to redo the analysis using the six bolts. I was going to get my Statics textbook out for this one myself, but I don't think this is a problem, albeit, I'd be damn sure to make sure those bolts were drilled right on the money AND reamed which it of course does call for. Even so, the NTSB never mentioned that joint failing. In fact, the folding occurred further outboard. I think that joint is fine, albeit pretty hairy looking at first glance.



You're leverage around those bolts with the virtual pivot in the center is roughly 20:1 = 74 inches /3.5 inches.



A rough calculation around that fixed center virtual pivot would give about 13,577lbs on one bolt, divided by 6 bolts is 2,262lbs at 1G, 6Gs is still only 13,577lbs per bolt.



That joint is fine.



 	  sonar1(at)cox.net wrote: 	
		  I ran some figures on the XL wing attachments and do not get good answers.

 

Can someone who has done statics calculations more recently than my 48 years ago check my work and tell me where I went wrong?



Not trying to revive last weeks discussions on the list - just want to talk to an engineer before I go flying.



Do not archive    ....................Fred Sanford....N9601....98%.......California

craig(at)craigandjean.com
Guest

Posted: Mon Mar 17, 2008 7:25 am Post subject: My figures don't compute

Does anything in the calculation speak to the tolerances of the six bolt

holes in the spars? I think that the ones in my QBK kit are too sloppy but

ZAC says that the tolerance is 12/1000". Since it is the outside two holes

on each side that are the worse (about 8/1000") it seems to me that those

two bolts won't be supporting a load at all. I'm looking for a tolerance

spec from an independent source.



 	  Quote: 	
		  From what little I have seen some of the RVs use a similar spar joint. Does

Van's specify a tolerance?
	




-- Craig



--

notsew_evets(at)frontiern
Guest

Posted: Mon Mar 17, 2008 7:33 am Post subject: My figures don't compute

WHAT ?

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ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Mon Mar 17, 2008 7:42 am Post subject: Re: My figures don't compute

That's pretty damn sloppy, 12 thou. Isn't a human hair like 1 or 2 thousands?



12 thou is almost the thickness of the aileron skin. 12 thou clearance under the fourth leg of a chair on a solid floor is noticable even.



I reamed my own holes and that reamer is the EXACT same size as the Aircraft Spruce bolt I put in there. The difference isn't even measureable with my dial caliper and that's accurate to 1/1000th. The hardest hole to drill and ream is the second one because it's only clamps and one bolt keeping things in alignment. Once you've got two, the rest are easy.



 	  craig(at)craigandjean.com wrote: 	
		  Does anything in the calculation speak to the tolerances of the six bolt

holes in the spars? I think that the ones in my QBK kit are too sloppy but

ZAC says that the tolerance is 12/1000". Since it is the outside two holes

on each side that are the worse (about 8/1000") it seems to me that those

two bolts won't be supporting a load at all. I'm looking for a tolerance

spec from an independent source.



 	  Quote: 	
		  From what little I have seen some of the RVs use a similar spar joint. Does

Van's specify a tolerance?

	




-- Craig



--

larry(at)macsmachine.com
Guest

Posted: Mon Mar 17, 2008 9:36 am Post subject: My figures don't compute

Craig,

The thing here not mentioned is torque compression values that provide 

surface friction. This friction offers more load-capability than simple 

bolt-to-hole contact-loading and should eliminate your concern for 

having less than a perfect fit at the spar holes.  It's a best reason 

for multiple bolts in this type of assembly.



Larry McFarland 601HDS at www.macsmachine.com

Craig Payne wrote:

 	  Quote: 	
		   



 Does anything in the calculation speak to the tolerances of the six bolt

 holes in the spars? I think that the ones in my QBK kit are too sloppy but

 ZAC says that the tolerance is 12/1000". Since it is the outside two holes

 on each side that are the worse (about 8/1000") it seems to me that those

 two bolts won't be supporting a load at all. I'm looking for a tolerance

 spec from an independent source.



 >From what little I have seen some of the RVs use a similar spar joint. Does

 Van's specify a tolerance?



 -- Craig

Jeyoung65(at)aol.com
Guest

Posted: Mon Mar 17, 2008 9:56 am Post subject: My figures don't compute

First this is my $0.01 because I do not know how this joint is made. But  think you have bolts on top of the spar and bolts on bottom of the spar so you  have a compression and a tension joint at the two location. Second the bolts  will be the last part to fail so you need to look at the aluminum. The one in  compression will fail last, I think, without running the numbers. Also  the joint will fail due to tear. Now run the numbers using the cross section of  the angle (if there is one there). Don"t forget the webb material.    Jerry DO NOT ARCHIVE

  In a message dated 3/17/2008 11:03:31 A.M. Eastern Daylight Time,  ashontz(at)nbme.org writes:

  	  Quote: 	
		  -->    Zenith-List message posted by: "ashontz"    <ashontz(at)nbme.org>

ashontz wrote:

 	  Quote: 	
		   There are six bolts    in there. I think you'd need to redo the analysis using the six bolts. I was    going to get my Statics textbook out for this one myself, but I don't think    this is a problem, albeit, I'd be damn sure to make sure those bolts were    drilled right on the money AND reamed which it of course does call for. Even    so, the NTSB never mentioned that joint failing. In fact, the folding occurred    further outboard. I think that joint is fine, albeit pretty hairy looking at    first glance.

 You're leverage around those bolts with the    virtual pivot in the center is roughly 20:1 = 74 inches /3.5 inches.

 A rough calculation around that fixed center virtual pivot would give    about 13,577lbs on one bolt, divided by 6 bolts is 2,262lbs at 1G, 6Gs is    still only 13,577lbs per bolt.

 That joint is fine.

 sonar1(at)cox.net wrote:

 > I ran some figures on the    XL wing attachments and do not get good answers.

 >  

    > Can someone who has done statics calculations more recently than my 48    years ago check my work and tell me where I went wrong?

 > 

    > Not trying to revive last weeks discussions on the list - just want to    talk to an engineer before I go flying.

 > 

 > Do not    archive    ....................Fred    Sanford....N9601....98%.......California

--------

Andy    Shontz

CH601XL -    Corvair

www.mykitlog.com/ashontz

Read this topic online    here:

http://forums.matronics.com/viewtopic.php?p=170377#170377

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

  [quote][b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Mon Mar 17, 2008 10:01 am Post subject: Re: My figures don't compute

I'm sure the clamping action provides quite a bit of friction, but I can't imagine the friction being the main shear resistance, nor the intended main shear resistance.



 	  larry(at)macsmachine.com wrote: 	
		  Craig,

The thing here not mentioned is torque compression values that provide 

surface friction. This friction offers more load-capability than simple 

bolt-to-hole contact-loading and should eliminate your concern for 

having less than a perfect fit at the spar holes.  It's a best reason 

for multiple bolts in this type of assembly.



Larry McFarland 601HDS at www.macsmachine.com

Craig Payne wrote:

 	  Quote: 	
		   



 Does anything in the calculation speak to the tolerances of the six bolt

 holes in the spars? I think that the ones in my QBK kit are too sloppy but

 ZAC says that the tolerance is 12/1000". Since it is the outside two holes

 on each side that are the worse (about 8/1000") it seems to me that those

 two bolts won't be supporting a load at all. I'm looking for a tolerance

 spec from an independent source.



 >From what little I have seen some of the RVs use a similar spar joint. Does

 Van's specify a tolerance?



 -- Craig

Gig Giacona

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

Posted: Mon Mar 17, 2008 10:23 am Post subject: Re: My figures don't compute

This entire thread is an excellent example of mental masturbation. It starts out with a calculation that is wrong primarily because it takes into account 4 bolts instead of 14 (because from a quick glance it doesn't even take into account the rear attach points and then goes down hill from there.



Sorry for the language if it offends anyone but I fine the thread rather offensive.



Is there anyway we could get back to questions regarding building and flying Zeniths? 



DO NOT ARCHIVE

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

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Mon Mar 17, 2008 10:38 am Post subject: Re: My figures don't compute

Just for the record, I was actually defending that joint.



 	  Gig Giacona wrote: 	
		  This entire thread is an excellent example of mental masturbation. It starts out with a calculation that is wrong primarily because it takes into account 4 bolts instead of 14 (because from a quick glance it doesn't even take into account the rear attach points and then goes down hill from there.



Sorry for the language if it offends anyone but I fine the thread rather offensive.



Is there anyway we could get back to questions regarding building and flying Zeniths? 



DO NOT ARCHIVE

Gig Giacona

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

Posted: Mon Mar 17, 2008 11:15 am Post subject: Re: My figures don't compute

Yes you did and you even tried to correct the first wildly wrong calculation but even you forgot to take into account the rear attach bolt. Which just goes to prove my point that this level of calculations needs to be left to professionals with ALL the data available to them.

[quote="ashontz"]Just for the record, I was actually defending that joint.



 	  Gig Giacona wrote: 	
		  This entire thread is an excellent example of mental masturbation. It starts out with a calculation that is wrong primarily because it takes into account 4 bolts instead of 14 (because from a quick glance it doesn't even take into account the rear attach points and then goes down hill from there.



Sorry for the language if it offends anyone but I fine the thread rather offensive.



Is there anyway we could get back to questions regarding building and flying Zeniths? 



DO NOT ARCHIVE

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

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Mon Mar 17, 2008 11:35 am Post subject: My figures don't compute

You should also remember that the lift is not distributed evenly over 

the length of the wing. The wing is tapered so the lift distribution 

also tapers off as you approach the tip. In fact, a tapered wing like 

this produces a fair approximation of an elliptical lift distribution. 

This puts the centroid of the lift closer to the root than the mid span 

point and reduces the lever arm and, therefore, the torque at the root. 

I suspect the centroid of lift is closer to one third the span than one 

half, say 50 inches instead of 74. It's been a long time since I used my 

aero engineering training, so this is just a rough estimate off the top 

of my head.

I'm not worried about that joint failing.

ashontz wrote:

 	  Quote: 	

 There are six bolts in there. I think you'd need to redo the analysis using the six bolts. I was going to get my Statics textbook out for this one myself, but I don't think this is a problem, albeit, I'd be damn sure to make sure those bolts were drilled right on the money AND reamed which it of course does call for. Even so, the NTSB never mentioned that joint failing. In fact, the folding occurred further outboard. I think that joint is fine, albeit pretty hairy looking at first glance.

 A rough calculation around that fixed center virtual pivot would give about 13,577lbs on one bolt, divided by 6 bolts is 2,262lbs, times 6Gs is still only 13,577lbs per bolt.

 That joint is fine.

 sonar1(at)cox.net wrote:

> I ran some figures on the XL wing attachments and do not get good answers.

>  

> Can someone who has done statics calculations more recently than my 48 years ago check my work and tell me where I went wrong?

>

> Not trying to revive last weeks discussions on the list - just want to talk to an engineer before I go flying.

>

> Do not archive    ....................Fred Sanford....N9601....98%.......California

-- 

Bryan Martin

B.S.A.E, U of Mich, '91

Zenith 601XL N61BM

Ram Subaru, Stratus redrive

Do Not Archive

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

planecrazydld(at)yahoo.co
Guest

Posted: Mon Mar 17, 2008 12:21 pm Post subject: My figures don't compute

do not archive



not being into that particular activity - but being interested in the mental gymnastics taking place here it is only fair to point out that Andy was correct in ignoring the single bolt common to the aft spar connection on each side - it is a simple pivot in panel bending. Total loads should include them though due to restraints on the planform due to the triangulation stability they add to the installation.



Gig Giacona <wr.giacona(at)suddenlink.net> wrote:[quote] --> Zenith-List message posted by: "Gig Giacona" 



Yes you did and you even tried to correct the first wildly wrong calculation but even you forgot to take into account the rear attach bolt. Which just goes to prove my point that this level of calculations needs to be left to professionals with ALL the data available to  them.

[quote="ashontz"]Just for the record, I was actually defending that joint.

Gig Giacona wrote:

 	  Quote: 	
		   This entire thread is an excellent example of mental masturbation. It starts out with a calculation that is wrong primarily because it takes into account 4 bolts instead of 14 (because from a quick glance it doesn't even take into account the rear attach points and then goes down hill from there.

 

 Sorry for the language if it offends anyone but I fine the thread rather offensive.

 

 Is there anyway we could get back to questions regarding building and flying Zeniths? 

 

 DO NOT ARCHIVE


	




--------

W.R. "Gig" Giacona

601XL Under Construction

See my progress at www.peoamerica.net/N601WR





Read this topic online  [quote][b]

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Mon Mar 17, 2008 12:30 pm Post subject: Re: My figures don't compute

I think they were discussing building a Zenith 601. I was enjoying the thread, mental masturbation?  If it really is profane or racist or sexist, then contact the administrator. If you find it annoying hit backspace!

Kevin

 	  Gig Giacona wrote: 	
		  This entire thread is an excellent example of mental masturbation. 



Is there anyway we could get back to questions regarding building and flying Zeniths? 



DO NOT ARCHIVE 	




do not archive

_________________
â€œAlways do what you are afraid to do.â€
R.W. Emerson (1803-1882)

"Real freedom is the sustained act of being an individual." WW - 2009

"Life is a good deal...it's worth it" Feb 1969
Dorothy McCune

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Mon Mar 17, 2008 12:55 pm Post subject: Re: My figures don't compute

If I'm not mistaken, the rear attach bolt is a single bolt and provides no upward resistance, it merely holds the rear of the wing in line with the front of the wing, no? The rear bolt only keeps the spar in line to take all of the bending moment.



There is no center spar on the rear because there is no bending force being acted upon on the rear of the spar. The main spar carries the load. Any bending moments on the the rear spar are transmitted to the main spar. Considering the center of lift of the wing is near the main spar, it shouldn't be a problem.



do not archive



[quote="Gig Giacona"]Yes you did and you even tried to correct the first wildly wrong calculation but even you forgot to take into account the rear attach bolt. Which just goes to prove my point that this level of calculations needs to be left to professionals with ALL the data available to them.

 	  ashontz wrote: 	
		  Just for the record, I was actually defending that joint.



 	  Gig Giacona wrote: 	
		  This entire thread is an excellent example of mental masturbation. It starts out with a calculation that is wrong primarily because it takes into account 4 bolts instead of 14 (because from a quick glance it doesn't even take into account the rear attach points and then goes down hill from there.



Sorry for the language if it offends anyone but I fine the thread rather offensive.



Is there anyway we could get back to questions regarding building and flying Zeniths? 



DO NOT ARCHIVE

Gig Giacona

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

Posted: Mon Mar 17, 2008 1:12 pm Post subject: Re: My figures don't compute

This forum has been overrun with first bad accident analysis and and now bad engineering data. This does NOTHING to help anyone either make an informed decision to build or not build a Zenith and it doesn't help anyone with questions or problems in building.



You guys said you were going to hire outside "expert" analysis. Why don't you do it and wait for the answer.



DO NOT ARCHIVE

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

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Mon Mar 17, 2008 1:22 pm Post subject: Re: My figures don't compute

Uh, we're talking about the forces in the spar and how the spar connects and the loads transmitted through them. As far as I'm concerned this part of this thread has nothing to do with accidents. The spar connect looks fine to me, plus, it's never been indicated in a NTSB report as a failure point.



I think, even without being an aeronautical engineer, pretty much anyone can calculate a rough estimate of the leveraged force through a beam with a force applied at distance x and a counteracting force or forces at distance y. And it's not too far of a stretch of the imagination to see that the spar will do just that, provided that the ribs and skins keep it in line. So, we've got ribs, spars and skins defining the shape of the wing as well as holding the main spar in line so that it can ultimately transmit that moment to the airframe to lift it. Not too complicated once you get down to the business end of the wing spar fitting in the center spar via 6 bolts and the rear bolt on the back of the wing keeping the wing from changing it's pitch relative to the fuselage. Sounds about right to me.



Now where I'd like to see the 3rd party analysis is on some of the internal structures in the wing itself.



do not archive



 	  Gig Giacona wrote: 	
		  This forum has been overrun with first bad accident analysis and and now bad engineering data. This does NOTHING to help anyone either make an informed decision to build or not build a Zenith and it doesn't help anyone with questions or problems in building.



You guys said you were going to hire outside "expert" analysis. Why don't you do it and wait for the answer.



DO NOT ARCHIVE

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Mon Mar 17, 2008 2:04 pm Post subject: My figures don't compute

Another point to remember is that the wings and included fuel make up a 

significant fraction of the gross weight of the airplane. The weight of 

the wings is not transmitted through the main spar attachment in flight. 

The swings support their own weight plus half the weight of the 

fuselage, instead of each wing supporting 660 lbs at the wing root, it's 

more like 500 lbs. This further improves the load situation at the wing 

root.



 	  Quote: 	
		   You should also remember that the lift is not distributed evenly over the length of the wing. The wing is tapered so the lift distribution also tapers off as you approach the tip. In fact, a tapered wing like this produces a fair approximation of an elliptical lift distribution. This puts the centroid of the lift closer to the root than the mid span point and reduces the lever arm and, therefore, the torque at the root. I suspect the centroid of lift is closer to one third the span than one half, say 50 inches instead of 74. It's been a long time since I used my aero engineering training, so this is just a rough estimate off the top of my head.

 

 I'm not worried about that joint failing.

 

 

 ashontz wrote:

> 

>

> There are six bolts in there. I think you'd need to redo the analysis using the six bolts. I was going to get my Statics textbook out for this one myself, but I don't think this is a problem, albeit, I'd be damn sure to make sure those bolts were drilled right on the money AND reamed which it of course does call for. Even so, the NTSB never mentioned that joint failing. In fact, the folding occurred further outboard. I think that joint is fine, albeit pretty hairy looking at first glance.

>

> A rough calculation around that fixed center virtual pivot would give about 13,577lbs on one bolt, divided by 6 bolts is 2,262lbs, times 6Gs is still only 13,577lbs per bolt.

>

> That joint is fine.

> sonar1(at)cox.net wrote:

>> I ran some figures on the XL wing attachments and do not get good answers.

>>  

>> Can someone who has done statics calculations more recently than my 48 years ago check my work and tell me where I went wrong?

>>

>> Not trying to revive last weeks discussions on the list - just want to talk to an engineer before I go flying.

>>

>> Do not archive    ....................Fred Sanford....N9601....98%.......California

>

 >
	




-- 

Bryan Martin

B.S.A.E, U of Mich, '91

Zenith 601XL N61BM

Ram Subaru, Stratus redrive

Do Not Archive

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

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