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wdaniell(at)etb.net.co
Guest

Posted: Mon Jan 17, 2011 5:23 am Post subject: Main wing bushings

For the assembled wisdom

 

I have a little slop in the main spar pins when I put them into each bushing separately – “a little slop” means when I wiggle the spar pins the ends move about 1/32.

 

There is no slop when the whole thing is assembled and the pins are a light push fit.

 

Is this normal?

 

Will

  [quote][b]

grahamsingleton(at)btinte
Guest

Posted: Mon Jan 17, 2011 8:37 am Post subject: Main wing bushings

Sounds OK to me William

Graham

From: William Daniell <wdaniell(at)etb.net.co>

To: europa-list(at)matronics.com

Sent: Monday, 17 January, 2011 13:19:05

Subject: Europa-List: Main wing bushings

For the assembled wisdom

I have a little slop in the main spar pins when I put them into each bushing separately â€“ â€œa little slopâ€ means when I wiggle the spar pins the ends move about 1/32.

There is no slop when the whole thing is assembled and the pins are a light push fit.

Is this normal?

Will

   [quote]http://www======================

[b]

JonSmith

Joined: 21 May 2010
Posts: 110

Posted: Mon Jan 17, 2011 10:51 am Post subject: Re: Main wing bushings

Mine is exactly the same.  In fact, I remember before doing the weight increase mod I put one of the brand new bushes on the brand new spar pins and was surprised by how much it wobbled about.  But when the spars are rigged together (4 bushes in line) there's no play whatsoever when the pin(s) are through them all.  I think it is normal.

_________________
G-TERN
Classic Mono

grahamsingleton(at)btinte
Guest

Posted: Mon Jan 17, 2011 11:13 am Post subject: Main wing bushings

First, the (black bolt)pins are undersize, (pip pins are spot on and the bushes pretty good)

The tightness is cause by miss alignment of the bushes, both linear and angular. Poor jigging in the factory using the black bolts. 



Avoid using a reamer to line them up, if they are bad warm up the redux and remove the miss aligned ones then rebond using better size pins for jigging.

Just do this with the two wings, forget the bushes in the seat back, they really are better with a loose fit because they increase loads on the wings with G forces. THe glider wing is different isn't it, (not seen one recently)

Graham

From: JonSmith <jonsmitheuropa(at)tiscali.co.uk>

To: europa-list(at)matronics.com

Sent: Monday, 17 January, 2011 18:51:28

Subject: Re: Main wing bushings



--> Europa-List message posted by: "JonSmith" <jonsmitheuropa(at)tiscali.co.uk (jonsmitheuropa(at)tiscali.co.uk)>



Mine is exactly the same.  In fact, I remember before doing the weight increase mod I put one of the brand new bushes on the brand new spar pins and was surprised by how much it wobbled about.  But when the spars are rigged together (4 bushes in line) there's no play whatsoever when the pin(s) are through them all.  I think it is normal.



--------

G-TERN

Classic  Mono





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=327312#327312

wdaniell(at)etb.net.co
Guest

Posted: Mon Jan 17, 2011 11:25 am Post subject: Main wing bushings

Phew

J

I had visions of yet another rework

Will

 

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of GRAHAM SINGLETON

Sent: 17 January, 2011 14:11

To: europa-list(at)matronics.com

Subject: Re: Re: Main wing bushings

 

First, the (black bolt)pins are undersize, (pip pins are spot on and the bushes pretty good)

The tightness is cause by miss alignment of the bushes, both linear and angular. Poor jigging in the factory using the black bolts. 



Avoid using a reamer to line them up, if they are bad warm up the redux and remove the miss aligned ones then rebond using better size pins for jigging.

Just do this with the two wings, forget the bushes in the seat back, they really are better with a loose fit because they increase loads on the wings with G forces. THe glider wing is different isn't it, (not seen one recently)

Graham



From: JonSmith <jonsmitheuropa(at)tiscali.co.uk>

To: europa-list(at)matronics.com

Sent: Monday, 17 January, 2011 18:51:28

Subject: Re: Main wing bushings



--> Europa-List message posted by: "JonSmith" <jonsmitheuropa(at)tiscali.co.uk (jonsmitheuropa(at)tiscali.co.uk)>



Mine is exactly the same.  In fact, I remember before doing the weight increase mod I put one of the brand new bushes on the brand new spar pins and was surprised by how much it wobbled about.  But when the spars are rigged together (4 bushes in line) there's no play whatsoever when the pin(s) are through them all.  I think it is normal.



--------

G-TERN

Classic Mono





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=327312#327312

http://www.matronics.com/Navigator?Europa-List

_ent also available via the Web               -Matt Dralle, List Admin.=======



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wdaniell(at)etb.net.co
Guest

Posted: Mon Jan 17, 2011 11:36 am Post subject: Main wing bushings

MY perception is that the bushings are quite soft which seems strange to me

Will

 

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of GRAHAM SINGLETON

Sent: 17 January, 2011 14:11

To: europa-list(at)matronics.com

Subject: Re: Re: Main wing bushings

 

First, the (black bolt)pins are undersize, (pip pins are spot on and the bushes pretty good)

The tightness is cause by miss alignment of the bushes, both linear and angular. Poor jigging in the factory using the black bolts. 



Avoid using a reamer to line them up, if they are bad warm up the redux and remove the miss aligned ones then rebond using better size pins for jigging.

Just do this with the two wings, forget the bushes in the seat back, they really are better with a loose fit because they increase loads on the wings with G forces. THe glider wing is different isn't it, (not seen one recently)

Graham



From: JonSmith <jonsmitheuropa(at)tiscali.co.uk>

To: europa-list(at)matronics.com

Sent: Monday, 17 January, 2011 18:51:28

Subject: Re: Main wing bushings



--> Europa-List message posted by: "JonSmith" <jonsmitheuropa(at)tiscali.co.uk (jonsmitheuropa(at)tiscali.co.uk)>



Mine is exactly the same.  In fact, I remember before doing the weight increase mod I put one of the brand new bushes on the brand new spar pins and was surprised by how much it wobbled about.  But when the spars are rigged together (4 bushes in line) there's no play whatsoever when the pin(s) are through them all.  I think it is normal.



--------

G-TERN

Classic Mono





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=327312#327312

http://www.matronics.com/Navigator?Europa-List

_ent also available via the Web               -Matt Dralle, List Admin.=======



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peterz(at)zutrasoft.com
Guest

Posted: Mon Jan 17, 2011 11:51 am Post subject: Main wing bushings

At least then they will not "fret"



Cheers,

Pete

A239



On Mon, Jan 17, 2011 at 2:33 PM, William Daniell <wdaniell(at)etb.net.co (wdaniell(at)etb.net.co)> wrote:

  [quote]

MY perception is that the bushings are quite soft which seems strange to me  



Will

 



  

[b]

wdaniell(at)etb.net.co
Guest

Posted: Mon Jan 17, 2011 2:01 pm Post subject: Main wing bushings

Good point!

 

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Peter Zutrauen

Sent: 17 January, 2011 14:48

To: europa-list(at)matronics.com

Subject: Re: Re: Main wing bushings



 

At least then they will not "fret"



Cheers,

Pete

A239

On Mon, Jan 17, 2011 at 2:33 PM, William Daniell <wdaniell(at)etb.net.co (wdaniell(at)etb.net.co)> wrote:

MY perception is that the bushings are quite soft which seems strange to me

Will

 





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grahamsingleton(at)btinte
Guest

Posted: Mon Jan 17, 2011 2:47 pm Post subject: Main wing bushings

They are, they're aluminium alloy but hard anodized. That's why it's better not to ream them

Graham

From: William Daniell <wdaniell(at)etb.net.co>

To: europa-list(at)matronics.com

Sent: Monday, 17 January, 2011 19:33:34

Subject: RE: Europa-List: Re: Main wing bushings

MY perception is that the bushings are quite soft which seems strange to me

Will

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of GRAHAM  SINGLETON

Sent: 17 January, 2011 14:11

To: europa-list(at)matronics.com

Subject: Re: Re: Main wing bushings

First, the (black bolt)pins are undersize, (pip pins are spot on and the bushes pretty good)

The tightness is cause by miss alignment of the bushes, both linear and angular. Poor jigging in the factory using the black bolts. 

Avoid using a reamer to line them up, if they are bad warm up the redux and remove the miss aligned ones then rebond using better size pins for jigging.

Just do this with the two wings, forget the bushes in the seat back, they really are better with a loose fit because they increase loads on the wings with G forces. THe glider wing is different isn't it,  (not seen one recently)

Graham

From: JonSmith <jonsmitheuropa(at)tiscali.co.uk>

To: europa-list(at)matronics.com

Sent: Monday, 17 January, 2011 18:51:28

Subject: Re: Main wing bushings

--> Europa-List message posted by: "JonSmith" <jonsmitheuropa(at)tiscali.co.uk (jonsmitheuropa(at)tiscali.co.uk)>

Mine is exactly the same.   In fact, I remember before doing the weight increase mod I put one of the brand new bushes on the brand new spar pins and was surprised by how much it wobbled about.  But when the spars are rigged together (4 bushes in line) there's no play whatsoever when the pin(s) are through them all.  I think it is normal.

--------

G-TERN

Classic Mono

Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=327312#327312

http://www.matronics.com/Navigator?Europa-List

_ent also available via the Web               -Matt Dralle, List Admin.=======

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budyerly(at)msn.com
Guest

Posted: Mon Jan 17, 2011 6:43 pm Post subject: Main wing bushings

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Will, and others,

 The play is because the black pins are undersized about .007 I think.   The main pip pin is about .499 so only a tiny amount of play is available.

 Normally, the oversized bushes allow what appears to be  excessive play when the wings are not rigged.  When the  plane is rigged, those sloppy bushes get hard to align unless you were superman  during the cockpit module build up and got the fuselage and wing bushes  just perfect.   I only have two aircraft that align so well, the wing  pins slide in easily, but that is only at 85 degrees and with the tips held just  right.  Hotter or colder, or with an untrained assistant, it is  tougher to push the pins in.  So what to do?

  

 Since none of us is superman, I many times have re-aligned the bushes on  final wing rigging by heating my spare tapered black pin until just too hot  to touch, but not sizzle (180F), and ram it home.  Let it set  overnight and the three bushes get aligned.  Once in a while, I do  have to put my 1/2 inch reamer into the pilot side hole and knock a  thousandth off for a nice hand fit of the pip pin because of the tighter  tolerances.  

  

 Note:  There is a good reason for using the pip pin when doing spar  alignment, especially on the glider wing retrofit.  Unfortunately we don't  have the luxury of setting our own bushes with the short  wings.  If we follow the instructions blindly and use just the bolts,  you won't quite get perfect alignment.  So just heat the pin and help the  bushes align.

  

 Please do not overheat your existing wing pin and destroy the heat  treating.  At 6 Gs, you would not believe the shear load on that pin.

  

 So don't rip everything out just yet, try a bit of heat and patience.   It's worth it.

  

 Regards,

 Bud Yerly

  

 [quote]   ---

grahamsingleton(at)btinte
Guest

Posted: Tue Jan 18, 2011 12:16 am Post subject: Main wing bushings

Thanks Bud,

now why didn't I think of that!

regards

Graham

From: Bud Yerly <budyerly(at)msn.com>

To: europa-list(at)matronics.com

Sent: Tuesday, 18 January, 2011 2:39:04

Subject: Re: Main wing bushings



       _filtered { font-family:Calibri;}  _filtered { font-family:Consolas;}  _filtered {margin:1.0in 1.0in 1.0in 1.0in;} P.MsoNormal { MARGIN:0in 0in 0pt;FONT-FAMILY:"serif";FONT-SIZE:12pt;} LI.MsoNormal { MARGIN:0in 0in 0pt;FONT-FAMILY:"serif";FONT-SIZE:12pt;} DIV.MsoNormal { MARGIN:0in 0in 0pt;FONT-FAMILY:"serif";FONT-SIZE:12pt;} A:link { COLOR:blue;TEXT-DECORATION:underline;} SPAN.MsoHyperlink { COLOR:blue;TEXT-DECORATION:underline;} A:visited { COLOR:purple;TEXT-DECORATION:underline;} SPAN.MsoHyperlinkFollowed { COLOR:purple;TEXT-DECORATION:underline;} PRE { MARGIN:0in 0in 0pt;FONT-FAMILY:"Courier New";FONT-SIZE:10pt;} SPAN.HTMLPreformattedChar { FONT-FAMILY:Consolas;} SPAN.apple-style-span { } SPAN.EmailStyle20 { FONT-FAMILY:"sans-serif";COLOR:#1f497d;} SPAN.EmailStyle21 { FONT-FAMILY:"sans-serif";COLOR:#1f497d;} .MsoChpDefault { FONT-SIZE:10pt;} DIV.WordSection1 { }    Will, and others,

 The play is because the black pins are undersized about .007 I think.   The main pip pin is about .499 so only a tiny amount of play is available.

 Normally, the oversized bushes allow what appears to be  excessive play when the wings are not rigged.  



Note:  There is a good reason for using the pip pin when doing spar  alignment, especially on the glider wing retrofit.  Unfortunately we don't  have the luxury of setting our own bushes with the short  wings.  If we follow the instructions blindly and use just the bolts,  you won't quite get perfect alignment.  So just heat the pin and help the  bushes align.

  

 Please do not overheat your existing wing pin and destroy the heat  treating.  At 6 Gs, you would not believe the shear load on that pin.

  

 So don't rip everything out just yet, try a bit of heat and patience.   It's worth it.

  

 Regards,

 Bud Yerly

  



[quote][b]

wdaniell(at)etb.net.co
Guest

Posted: Tue Jan 18, 2011 4:36 am Post subject: Main wing bushings

Thanks Bud

Will

 

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Bud Yerly

Sent: 17 January, 2011 21:39

To: europa-list(at)matronics.com

Subject: Re: Main wing bushings

 

Will, and others,



The play is because the black pins are undersized about .007 I think.  The main pip pin is about .499 so only a tiny amount of play is available.



Normally, the oversized bushes allow what appears to be excessive play when the wings are not rigged.  When the plane is rigged, those sloppy bushes get hard to align unless you were superman during the cockpit module build up and got the fuselage and wing bushes just perfect.   I only have two aircraft that align so well, the wing pins slide in easily, but that is only at 85 degrees and with the tips held just right.  Hotter or colder, or with an untrained assistant, it is tougher to push the pins in.  So what to do?



 



Since none of us is superman, I many times have re-aligned the bushes on final wing rigging by heating my spare tapered black pin until just too hot to touch, but not sizzle (180F), and ram it home.  Let it set overnight and the three bushes get aligned.  Once in a while, I do have to put my 1/2 inch reamer into the pilot side hole and knock a thousandth off for a nice hand fit of the pip pin because of the tighter tolerances.  



 



Note:  There is a good reason for using the pip pin when doing spar alignment, especially on the glider wing retrofit.  Unfortunately we don't have the luxury of setting our own bushes with the short wings.  If we follow the instructions blindly and use just the bolts, you won't quite get perfect alignment.  So just heat the pin and help the bushes align.



 



Please do not overheat your existing wing pin and destroy the heat treating.  At 6 Gs, you would not believe the shear load on that pin.



 



So don't rip everything out just yet, try a bit of heat and patience.  It's worth it.



 



Regards,



Bud Yerly



 

  [quote][b]

kheindl(at)msn.com
Guest

Posted: Tue Jan 18, 2011 6:16 am Post subject: Main wing bushings

When I have help with the rigging then it is quite easy to locate the pins in my case, although the glider wings are quite a handful or two. But on my own it is more difficult. A couple of years ago I inherited a tapered 1/2 inch pin from an aircraft engineer and that works just fine. I tap it in carefully with a plastic hammer, and can then insert the pip pin into the other hole with ease. I don't now where one would buy such a tool.

Karl

From: budyerly(at)msn.com

To: europa-list(at)matronics.com

Subject: Re: Main wing bushings

Date: Mon, 17 Jan 2011 21:39:04 -0500

       (at)page WordSection1 {size:8.5in 11.0in;} .ExternalClass P.ecxMsoNormal {font-family:'Times New Roman','serif';font-size:12pt;} .ExternalClass LI.ecxMsoNormal {font-family:'Times New Roman','serif';font-size:12pt;} .ExternalClass DIV.ecxMsoNormal {font-family:'Times New Roman','serif';font-size:12pt;} .ExternalClass A:link {color:blue;text-decoration:underline;} .ExternalClass SPAN.ecxMsoHyperlink {color:blue;text-decoration:underline;} .ExternalClass A:visited {color:purple;text-decoration:underline;} .ExternalClass SPAN.ecxMsoHyperlinkFollowed {color:purple;text-decoration:underline;} .ExternalClass PRE {font-family:'Courier New';font-size:10pt;} .ExternalClass SPAN.ecxHTMLPreformattedChar {font-family:Consolas;} .ExternalClass SPAN.ecxapple-style-span {;} .ExternalClass SPAN.ecxEmailStyle20 {font-family:'Calibri','sans-serif';color:#1f497d;} .ExternalClass SPAN.ecxEmailStyle21 {font-family:'Calibri','sans-serif';color:#1f497d;} .ExternalClass .ecxMsoChpDefault {font-size:10pt;} .ExternalClass DIV.ecxWordSection1 {page:WordSection1;}     Will, and others,

 The play is because the black pins are undersized about .007 I think.   The main pip pin is about .499 so only a tiny amount of play is available.

 Normally, the oversized bushes allow what appears to be  excessive play when the wings are not rigged.  When the  plane is rigged, those sloppy bushes get hard to align unless you were superman  during the cockpit module build up and got the fuselage and wing bushes  just perfect.   I only have two aircraft that align so well, the wing  pins slide in easily, but that is only at 85 degrees and with the tips held just  right.  Hotter or colder, or with an untrained assistant, it is  tougher to push the pins in.  So what to do?

 Since none of us is superman, I many times have re-aligned the bushes on  final wing rigging by heating my spare tapered black pin until just too hot  to touch, but not sizzle (180F), and ram it home.  Let it set  overnight and the three bushes get aligned.  Once in a while, I do  have to put my 1/2 inch reamer into the pilot side hole and knock a  thousandth off for a nice hand fit of the pip pin because of the tighter  tolerances.  

 Note:  There is a good reason for using the pip pin when doing spar  alignment, especially on the glider wing retrofit.  Unfortunately we don't  have the luxury of setting our own bushes with the short  wings.  If we follow the instructions blindly and use just the bolts,  you won't quite get perfect alignment.  So just heat the pin and help the  bushes align.

 Please do not overheat your existing wing pin and destroy the heat  treating.  At 6 Gs, you would not believe the shear load on that pin.

 So don't rip everything out just yet, try a bit of heat and patience.   It's worth it.

 Regards,

 Bud Yerly

 [quote]   ---

kingsnjan(at)westnet.com.
Guest

Posted: Wed Jan 19, 2011 1:30 am Post subject: Main wing bushings

Graham,

  

 You said "Just do this with the two  wings, forget the bushes in the seat back, they really are better with a loose  fit because they increase loads on the wings with G forces."

  

 I am heartened to see you feel  like I do about the bushes in the seat back.  For the life of me, I have  never been able to understand the purpose of them except that they may prohibit  relative movement between the wings and the fuselage in the span  direction.  In this case one bush would be sufficient and would not load up  the cockpit module/spars as I suspect it does now with the two bushes when under  high G loads.

  

 Just my 2c worth.

  

 Regarding the slop between the pins and the bushes,  I did the AUW increase mod and had to replace all original 3/8" bushes with the  1/2" ones.  In doing the setting up, I purchased two 1/2" HT bolts and  spray painted them with several coats of paint until they were a neat fit.   Probably not the smartest idea around but with the limited resources I had it  worked and my wing pins are a delight to install and remove.

  

 Weather seems to be settling down a bit here now,  we have had a drought for the last 24 hrs !!

  

 Cheers

 Kingsley

  

 do not archive

    [quote][b]

wdaniell(at)etb.net.co
Guest

Posted: Wed Jan 19, 2011 3:58 am Post subject: Main wing bushings

KingsleyI don't understand due to my limited knowledge of the engineering.What alternative might there be?WillFrom:  Kingsley Hurst <kingsnjan(at)westnet.com.au> 

Sender:  "owner-europa-list-server(at)matronics.com" 	<owner-europa-list-server(at)matronics.com> 

Date: Wed, 19 Jan 2011 04:26:38 -0500

To: europa-list(at)matronics.com<europa-list(at)matronics.com>

ReplyTo:  "europa-list(at)matronics.com" <europa-list(at)matronics.com> 

Subject: Re: Europa-List: Re: Main wing bushings

 Graham,

 You said "Just do this with the two  wings, forget the bushes in the seat back, they really are better with a loose  fit because they increase loads on the wings with G forces."

 I am heartened to see you feel  like I do about the bushes in the seat back.  For the life of me, I have  never been able to understand the purpose of them except that they may prohibit  relative movement between the wings and the fuselage in the span  direction.  In this case one bush would be sufficient and would not load up  the cockpit module/spars as I suspect it does now with the two bushes when under  high G loads.

 Just my 2c worth.

 Regarding the slop between the pins and the bushes,  I did the AUW increase mod and had to replace all original 3/8" bushes with the  1/2" ones.  In doing the setting up, I purchased two 1/2" HT bolts and  spray painted them with several coats of paint until they were a neat fit.   Probably not the smartest idea around but with the limited resources I had it  worked and my wing pins are a delight to install and remove.

 Weather seems to be settling down a bit here now,  we have had a drought for the last 24 hrs !!

 Cheers

 Kingsley

 do not archive

    [quote][b]

peterz(at)zutrasoft.com
Guest

Posted: Wed Jan 19, 2011 4:32 am Post subject: Main wing bushings

I'm trying to visualize the geometry of the high-g loading scenario wrt to the seat-back bushes imparting additional/undesired stress on the spars.



Is this due to the distance between inner and outer spar bushings decreasing when the spars are flexed (due to the arc)? Or is it the twisting moment imparted on the spars due to the one-sided mount (although aren't the lift pins supposed to take the vertical G-loading)?

  

Cheers,

Pete 

A239



On Wed, Jan 19, 2011 at 4:26 AM, Kingsley Hurst <kingsnjan(at)westnet.com.au (kingsnjan(at)westnet.com.au)> wrote:

  [quote]       Graham,

  

 You said "Just do this with the two  wings, forget the bushes in the seat back, they really are better with a loose  fit because they increase loads on the wings with G forces."

  

 I am heartened to see you feel  like I do about the bushes in the seat back.  For the life of me, I have  never been able to understand the purpose of them except that they may prohibit  relative movement between the wings and the fuselage in the span  direction.  In this case one bush would be sufficient and would not load up  the cockpit module/spars as I suspect it does now with the two bushes when under  high G loads.

  

 Just my 2c worth.

  

 Regarding the slop between the pins and the bushes,  I did the AUW increase mod and had to replace all original 3/8" bushes with the  1/2" ones.  In doing the setting up, I purchased two 1/2" HT bolts and  spray painted them with several coats of paint until they were a neat fit.   Probably not the smartest idea around but with the limited resources I had it  worked and my wing pins are a delight to install and remove.

  

 Weather seems to be settling down a bit here now,  we have had a drought for the last 24 hrs !!

  

 Cheers

 Kingsley

  

 do not archive

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[b]

grahamsingleton(at)btinte
Guest

Posted: Wed Jan 19, 2011 8:02 am Post subject: Main wing bushings

Pete

in +ve G the wing (& spar) bends.so the spar pins are trying to push down while the lift pins, designed to take the lift loads, are pushing up. So each of these conflicting tendencies adds to the loading of the other. THe twist is also a problem probably the same reason

I bet Bud has a better way of describing it 

Graham

From: Peter Zutrauen <peterz(at)zutrasoft.com>

To: europa-list(at)matronics.com

Sent: Wednesday, 19 January, 2011 12:28:02

Subject: Re: Re: Main wing bushings



I'm trying to visualize the geometry of the high-g loading scenario wrt to the seat-back bushes imparting additional/undesired stress on the spars.



Is this due to the distance between inner and outer spar bushings decreasing when the spars are flexed (due to the arc)? Or is it the twisting moment imparted on the spars due to the one-sided mount (although aren't the lift pins supposed to take the vertical G-loading)?

  

Cheers,

Pete 

A239



On Wed, Jan 19, 2011 at 4:26 AM, Kingsley Hurst <kingsnjan(at)westnet.com.au (kingsnjan(at)westnet.com.au)> wrote:

  [quote]       Graham,

  

 You said "Just do this with the two  wings, forget the bushes in the seat back, they really are better with a loose  fit because they increase loads on the wings with G forces."

  

 I am heartened to see you feel  like I do about the bushes in the seat back.  For the life of me, I have  never been able to understand the purpose of them except that they may prohibit  relative movement between the wings and the fuselage in the span  direction.  In this case one bush would be sufficient and would not load up  the cockpit module/spars as I suspect it does now with the two bushes when under  high G loads.

  

 Just my 2c worth.

  

 Regarding the slop between the pins and the bushes,  I did the AUW increase mod and had to replace all original 3/8" bushes with the  1/2" ones.  In doing the setting up, I purchased two 1/2" HT bolts and  spray painted them with several coats of paint until they were a neat fit.   Probably not the smartest idea around but with the limited resources I had it  worked and my wing pins are a delight to install and remove.

  

 Weather seems to be settling down a bit here now,  we have had a drought for the last 24 hrs !!

  

 Cheers

 Kingsley

  

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peterz(at)zutrasoft.com
Guest

Posted: Wed Jan 19, 2011 8:36 am Post subject: Main wing bushings

Yes, I see now (since the spar pins are inboard of the lift pins and along the arc of the bending spars).



Thx!

Pete

A239



On Wed, Jan 19, 2011 at 10:57 AM, GRAHAM SINGLETON <grahamsingleton(at)btinternet.com (grahamsingleton(at)btinternet.com)> wrote:

  [quote]  Pete

in +ve G the wing (& spar) bends.so the spar pins are trying to push down while the lift pins, designed to take the lift loads, are pushing up. So each of these conflicting tendencies adds to the loading of the other. THe twist is also a problem probably the same reason

  I bet Bud has a better way of describing it [img][/img]

Graham

From: Peter Zutrauen <peterz(at)zutrasoft.com (peterz(at)zutrasoft.com)>  

To: europa-list(at)matronics.com (europa-list(at)matronics.com)



Sent: Wednesday, 19 January, 2011 12:28:02  

Subject: Re: Europa-List: Re: Main wing bushings

I'm trying to visualize the geometry of the high-g loading scenario wrt to the seat-back bushes imparting additional/undesired stress on the spars.

  

Is this due to the distance between inner and outer spar bushings decreasing when the spars are flexed (due to the arc)? Or is it the twisting moment imparted on the spars due to the one-sided mount (although aren't the lift pins supposed to take the vertical G-loading)?

    

Cheers,

Pete 

A239



On Wed, Jan 19, 2011 at 4:26 AM, Kingsley Hurst <kingsnjan(at)westnet.com.au (kingsnjan(at)westnet.com.au)> wrote:

     	  Quote: 	
		         Graham,

  

 You said "Just do this with the two  wings, forget the bushes in the seat back, they really are better with a loose  fit because they increase loads on the wings with G forces."

  

 I am heartened to see you feel  like I do about the bushes in the seat back.  For the life of me, I have  never been able to understand the purpose of them except that they may prohibit  relative movement between the wings and the fuselage in the span  direction.  In this case one bush would be sufficient and would not load up  the cockpit module/spars as I suspect it does now with the two bushes when under  high G loads.

  

 Just my 2c worth.

  

 Regarding the slop between the pins and the bushes,  I did the AUW increase mod and had to replace all original 3/8" bushes with the  1/2" ones.  In doing the setting up, I purchased two 1/2" HT bolts and  spray painted them with several coats of paint until they were a neat fit.   Probably not the smartest idea around but with the limited resources I had it  worked and my wing pins are a delight to install and remove.

  

 Weather seems to be settling down a bit here now,  we have had a drought for the last 24 hrs !!

  

 Cheers

 Kingsley

  

 do not archive

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[b]

kingsnjan(at)westnet.com.
Guest

Posted: Wed Jan 19, 2011 7:40 pm Post subject: Main wing bushings

Hello Will,

  

 I am not suggesting there is any alternative for us  as builders.  The design "as is" obviously fits the bill so the old adage,  "if it ain't broke, don't fix it" is appropriate.

  

 From a designer's point of view however, if you  inspect the various methods employed by sailplane manufacturers, there are  possibly better ways of doing it.  I have never seen a sailplane with the  same set-up as the Europa but that doesn't mean there isn't any.  Ivan Shaw  did get some ideas from sailplanes so maybe he found one . . . . I  dunno!

  

 Cheers

 Kingsley

  

 do not archive

  

 [quote]   ---

grahamsingleton(at)btinte
Guest

Posted: Thu Jan 20, 2011 12:56 am Post subject: Main wing bushings

Kingsley

Ivan didn't do the stress calcs. As I understand it, (I'm not a stress man either) you could leave out the bushes in the seat back. 

The motor glider has been redesigned and the spar tangs have been stiffened. I don't know if the seat back bushes were deleted. I just asked Ivan and he doesn't know either (or chose not to remember) 

I guess Bud might tell us?

Graham

From: Kingsley Hurst <kingsnjan(at)westnet.com.au>

To:  europa-list(at)matronics.com

Sent: Thursday, 20 January, 2011 3:33:19

Subject: Re: Re: Main wing bushings



ï»¿    DIV { MARGIN:0px;}    Hello Will,

  

 I am not suggesting there is any alternative for us  as builders.  The design "as is" obviously fits the bill so the old adage,  "if it ain't broke, don't fix it" is appropriate.

  

 From a designer's point of view however, if you  inspect the various methods employed by sailplane manufacturers, there are  possibly better ways of doing it.  I have never seen a sailplane with the  same set-up as the Europa but that doesn't mean there isn't any.  Ivan Shaw  did get some ideas from sailplanes so maybe he found one . . . . I  dunno!

  

 Cheers

 Kingsley

  

 do not archive

  

 [quote]   ---

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