Today's Message Index:
----------------------
1. 12:37 AM - Re: Re: Main wing bushings (Nigel Graham)
2. 02:06 AM - Re: Main wing bushings (flyingphil2)
3. 02:13 AM - Re: Re: Main wing bushings (GRAHAM SINGLETON)
4. 04:43 AM - Re: Re: Main wing bushings (William Daniell)
5. 06:09 AM - EuropaOwners (Steve Dunsmuir)
6. 08:36 AM - Re: EuropaOwners (GRAHAM SINGLETON)
7. 08:44 AM - Re: EuropaOwners (Raimo Toivio)
8. 09:44 AM - off topic (Fred Klein)
9. 10:10 AM - Re: Re: Main wing bushings (Kevin Challis)
10. 11:54 AM - Re: Re: Main wing bushings (Paul McAllister)
11. 12:05 PM - Re: off topic (Bill Henderson)
12. 02:14 PM - Re: Re: Main wing bushings (Duncan & Ami)
13. 02:26 PM - Re: Re: Main wing bushings (Duncan & Ami)
14. 02:32 PM - Re: Re: Main wing bushings (Duncan & Ami)
15. 05:21 PM - Re: Re: Main wing bushings (GRAHAM SINGLETON)
16. 07:34 PM - Re: Re: Main wing bushings (Bud Yerly)
17. 07:46 PM - Re: Re: Main wing bushings (Bud Yerly)
Message 1
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Subject: | Re: Main wing bushings |
This has sparked an extremely interesting and thought provoking debate.
The only real solution is to model the aircraft using Finite Element
Analysis to truly see how the airframe moves under differing load
conditions.
Any Europa builders use FEA?
Nigel
On 24/01/2011 23:19, GRAHAM SINGLETON wrote:
> Not convinced Duncan. The spar resists bending and the leverage is
> enormous, from the centre of lift of the wing 30% span? The load on
> the root ribs is shear and some bending of the pins. Don't forget the
> lift load is a spread load whereas the spar bending of the tangs is a
> point load applied by the spar pins.
> You are right about the stiffening of the fuselage side. We really
> should have flexible sockets at the LE as well as the TE.
> I still believe the lift pins (in the root rib) should carry all the
> lift loads and the spar pins all the bending loads. That's why the
> tangs needed to be strengthened on the glider.
>
> Graham
>
> ------------------------------------------------------------------------
> *From:* Duncan & Ami <ami-mcfadyean@talktalk.net>
> *To:* europa-list@matronics.com
> *Sent:* Monday, 24 January, 2011 21:58:21
> *Subject:* RE: Europa-List: Re: Main wing bushings
>
> <<..would stiffen the structure in such a way that it could lead to
> overloading of the forward lift pin>>
>
> Ian,
>
> How does that work, if the lift pins are designed to carry the lift
> loads in the first place, there being no greater load available?!
>
> Actually, it was stiffening in *bending* that might restrain rotation
> of the lift pin that was the issue, resulting in an additional bending
> load (not lift load) being applied to the forward lift pin. The LAA
> were offered a spherical socket that would articulate and remove the
> bending load on the pin, but declined to accept that.
>
> However, you are on right path, The earlier discussion in this thread
> presumes that the spar flexes, as it indeed doe. But actually the spar
> (loaded in this direction) is the least flexible part of the whole
> system. What about the forward and aft portions of the root rib? Lets
> say these ribs have equal section and I as the spar, but being
> laid-up at +/- 45 degrees have x1.41 the elasticity of the
> unidirectional spar (in the direction of principal stress), added to
> which the length of these flexing root ribs (between lift pin and
> spar) is longer than the offset between lift pins and spar pins. So,
> as the root ribs will flex more than the spar and it follows that the
> leverage effect between the longitudinal offset of lift pin and spar
> pin centres is removed, or reversed to the extent that the spar pins
> share some lift load.
>
> As you say, the flexing of the fus side also contributes, albeit this
> had to be stiffened-up to prevent pin disengagement.
>
> Previously I have put a small finger down one of the (1/2) spar pin
> holes with the wings rigged, while someone else rather violently
> loaded the wing, albeit not even near to 1g. But there was no hint of
> the leverage effect or the spar hole flexing downwards relative to
> the pin hole in the seat back.
>
> Rgds.,
>
> Duncan McF.
>
> -----Original Message-----
> *From:* owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com] *On Behalf Of *G-IANI
> *Sent:* 24 January 201112:34
> *To:* europa-list@matronics.com
> *Subject:* RE: Europa-List: Re: Main wing bushings
>
> In support of Bud and Petes notes I can confirm that flexing of the
> fuselage is important. The LAA had considerable concerns that the
> tail dragger conversion would stiffen the structure in such a way that
> it could lead to overloading of the forward lift pin.
>
> Ian Rickard G-IANI XS Trigear, 300hours
> Europa Club Mods Specialist
> e-mail g-iani@ntlworld.com
>
> * *
> * *
> **
> **
> **
> **
> **
> **
> **
> *http://www.matronics.com/Navigator?Europa-List*
> **
> **
> **
> **
> **
> *http://forums.matronics.com*
> **
> **
> **
> **
> **
> *http://www.matronics.com/contribution*
> **
> * *
> *
>
> " target="_blank" href="http://forums.matronics.com">http://forums.matr --> *
> **
>
>
> **
Message 2
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Subject: | Re: Main wing bushings |
All this talk of taildraggers has got me interested now .....
The new owners of Europa use FEA. Also, I believe that they have scanned some
or all of the aircraft. They would therefore be the best people to do this if
they were motivated.
Alternatively, this could be achieved through other channels if they were prepared
to release the CAD data. It's up them really.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328374#328374
Message 3
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Subject: | Re: Main wing bushings |
Anyone chat with them at the Dinner?=0AGraham=0A=0A=0A=0A=0A_______________
_________________=0AFrom: flyingphil2 <ptiller@lolacars.com>=0ATo: europa-l
ist@matronics.com=0ASent: Tuesday, 25 January, 2011 10:03:43=0ASubject: Eur
lyingphil2" <ptiller@lolacars.com>=0A=0AAll this talk of taildraggers has g
ot me interested now .....=0A=0AThe new owners of Europa use FEA. Also, I
believe that they have scanned some =0Aor all of the aircraft. They would
therefore be the best people to do this if =0Athey were motivated.=0A=0AAlt
ernatively, this could be achieved through other channels if they were =0Ap
repared to release the CAD data. It's up them really.=0A=0A=0A=0A=0ARead t
his topic online here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=3
=
Message 4
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Subject: | Re: Main wing bushings |
Here is a question with respect to this topic =93 albeit a bit of
a sensitive one. But maybe it is the acid test.
Is there any experience of this part of the aircraft failing apart?
=93 I have heard of other failures but not any failures in this
bit.
I assume that we have experience on the forum of extreme stress on the
airframe amongst the forum members whether deliberately or as a result
of turbulence.
So I guess the question is =9Cdoes it work in practice?=9D
Will
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of GRAHAM
SINGLETON
Sent: 25 January, 2011 05:11
Subject: Re: Europa-List: Re: Main wing bushings
Anyone chat with them at the Dinner?
Graham
_____
From: flyingphil2 <ptiller@lolacars.com>
Sent: Tuesday, 25 January, 2011 10:03:43
Subject: Europa-List: Re: Main wing bushings
All this talk of taildraggers has got me interested now .....
The new owners of Europa use FEA. Also, I believe that they have
scanned some or all of the aircraft. They would therefore be the best
people to do this if they were motivated.
Alternatively, this could be achieved through other channels if they
were prepared to release the CAD data. It's up them really.
Message 5
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|
Just to let everyone know, there is a problem with the Domain name server, not
the server.
All your files and photo's are fine. I have a backup that was 4 hours old when
the DNS stopped linking. The site will be back it's just a matter of when and
where.
Much more importantly is Jos ok? Hopefully he's just vacationing in Florida.
I haven't been able to contact him for a while.....
Steve Dunsmuir
EuropaOwners
Message 6
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Subject: | Re: EuropaOwners |
steve=0AI noticed him on Skype a couple of days ago but haven't talked to h
im for a =0Awhile. I'll call him next time I see him there=0AGraham=0A=0A
=0A=0A=0A________________________________=0AFrom: Steve Dunsmuir <EuropaFor
um@comcast.net>=0ATo: europa-list@matronics.com=0ASent: Tuesday, 25 January
, 2011 14:04:35=0ASubject: Europa-List: EuropaOwners=0A=0A--> Europa-List m
essage posted by: Steve Dunsmuir <EuropaForum@comcast.net>=0A=0AJust to let
everyone know, there is a problem with the Domain name server, not =0Athe
server.=0AAll your files and photo's are fine. I have a backup that was 4 h
ours old when =0Athe DNS stopped linking. The site will be back it's just a
matter of when and =0Awhere.=0AMuch more importantly is Jos ok? Hopefully
he's just vacationing in Florida. =0AI haven't been able to contact him for
=======
Message 7
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Subject: | Re: EuropaOwners |
I called him and he is ok and will fix it.
Raimo Toivio OH-XRT 200 hrs
-----Alkuperinen viesti-----
From: Steve Dunsmuir
Sent: Tuesday, January 25, 2011 4:04 PM
Subject: Europa-List: EuropaOwners
<EuropaForum@comcast.net>
Just to let everyone know, there is a problem with
the Domain name server, not the server.
All your files and photo's are fine. I have a
backup that was 4 hours old when the DNS stopped
linking. The site will be back it's just a matter
of when and where.
Much more importantly is Jos ok? Hopefully he's
just vacationing in Florida.
I haven't been able to contact him for a
while.....
Steve Dunsmuir
EuropaOwners
browse
Un/Subscription,
FAQ,
http://www.matronics.com/Navigator?Europa-List
Forums!
List Admin.
Message 8
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|
the challenges of pitching decks & night aircraft carrier ops
<http://www.youtube.com/watch_popup?v=4gGMI8d3vLs>
<http://www.youtube.com/watch_popup?v=S0yj70QbBzg>
do not archive
Message 9
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Subject: | Re: Main wing bushings |
Hi
I have flown in mountain wave in a valley in the pyrenees. It was bad, my wi
fe cried! I hope i never test the plane like that again. But the plane was a
nd is fine.
Kevin
On 25 Jan 2011, at 12:39, "William Daniell" <wdaniell@etb.net.co> wrote:
> Here is a question with respect to this topic =93 albeit a bit of a s
ensitive one. But maybe it is the acid test.
>
>
>
> Is there any experience of this part of the aircraft failing apart?
=93 I have heard of other failures but not any failures in this bit.
>
>
>
> I assume that we have experience on the forum of extreme stress on the air
frame amongst the forum members whether deliberately or as a result of turbu
lence.
>
>
>
> So I guess the question is =9Cdoes it work in practice?=9D
>
>
>
> Will
>
>
>
> From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-ser
ver@matronics.com] On Behalf Of GRAHAM SINGLETON
> Sent: 25 January, 2011 05:11
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Re: Main wing bushings
>
>
>
> Anyone chat with them at the Dinner?
> Graham
>
>
>
> From: flyingphil2 <ptiller@lolacars.com>
> To: europa-list@matronics.com
> Sent: Tuesday, 25 January, 2011 10:03:43
> Subject: Europa-List: Re: Main wing bushings
>
>
> All this talk of taildraggers has got me interested now .....
>
> The new owners of Europa use FEA. Also, I believe that they have scanned s
ome or all of the aircraft. They would therefore be the best people to do t
his if they were motivated.
>
> Alternatively, this could be achieved through other channels if they were p
repared to release the CAD data. It's up them really.
>
>
>
>
>
>
>
==========================
=========
==========================
=========
==========================
=========
==========================
=========
>
Message 10
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Subject: | Re: Main wing bushings |
On Tuesday, January 25, 2011, Kevin Challis <kevinmarie@blueyonder.co.uk> wrote:
> Hi
> I have flown in mountain wave in a valley in thepyrenees. It was bad, my wife
cried! I hope i never test the plane like that again. But the plane was and is
fine.
>
> Kevin
>
I had ATC vector me into a big ass'd cloud one time. Instead of
responding 'unable' I took the vector. Gee it was bad, really bad. My
wife didn't cry but I nearly did. The plane was fine and I was a
little smarter. I'm pretty sure I am going to break before my Europa
does
Paul
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Looks like the Europa Owners web site is back up.
Bill
A010
Message 12
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Subject: | Re: Main wing bushings |
Graham,
I agree with all that you say, so unsure why you're not convinced.
The lift load is spread on the wings, but comes to a point at the lift
pins;
the stress path being either via the spar and root rib, and/or directly
through the wing skin to the root rib (assuming for the argument no lift
contribution from the spar pins).
I recall that when a Europa wing broke in the early tests, it broke
across
the D-box (LE of wing) adjacent to the rib (and was subsequently
reinforced
in that area).
Meaning that this part was overstressed, obviously, but the strain at
failure (being a material constant) was greatest in this part of the
structure (i.e. up to the point of failure, the area around the rib had
flexed more than any other part of similar 'I).
Duncan.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of GRAHAM
SINGLETON
Sent: 24 January 2011 23:20
Subject: Re: Europa-List: Re: Main wing bushings
Not convinced Duncan. The spar resists bending and the leverage is
enormous,
from the centre of lift of the wing 30% span? The load on the root ribs
is
shear and some bending of the pins. Don't forget the lift load is a
spread
load whereas the spar bending of the tangs is a point load applied by
the
spar pins.
You are right about the stiffening of the fuselage side. We really
should
have flexible sockets at the LE as well as the TE.
I still believe the lift pins (in the root rib) should carry all the
lift
loads and the spar pins all the bending loads. That's why the tangs
needed
to be strengthened on the glider.
Graham
_____
From: Duncan & Ami <ami-mcfadyean@talktalk.net>
Sent: Monday, 24 January, 2011 21:58:21
Subject: RE: Europa-List: Re: Main wing bushings
<<.. would stiffen the structure in such a way that it could lead to
overloading of the forward lift pin >>
Ian,
How does that work, if the lift pins are designed to carry the lift
loads in
the first place, there being no greater load available?!
Actually, it was stiffening in bending that might restrain rotation of
the
lift pin that was the issue, resulting in an additional bending load
(not
lift load) being applied to the forward lift pin. The LAA were offered a
spherical socket that would articulate and remove the bending load on
the
pin, but declined to accept that.
However, you are on right path, The earlier discussion in this thread
presumes that the spar flexes, as it indeed doe. But actually the spar
(loaded in this direction) is the least flexible part of the whole
system.
What about the forward and aft portions of the root rib? Let's say these
ribs have equal section and 'I' as the spar, but being laid-up at +/- 45
degrees have x1.41 the elasticity of the unidirectional spar (in the
direction of principal stress), added to which the length of these
flexing
root ribs (between lift pin and spar) is longer than the offset between
lift
pins and spar pins. So, as the root ribs will flex more than the spar
and it
follows that the "leverage" effect between the longitudinal offset of
lift
pin and spar pin centres is removed, or reversed to the extent that the
spar
pins share some lift load.
As you say, the flexing of the fus side also contributes, albeit this
had to
be stiffened-up to prevent pin disengagement.
Previously I have put a small finger down one of the (1/2") spar pin
holes
with the wings rigged, while someone else rather violently loaded the
wing,
albeit not even near to 1g. But there was no hint of the "leverage"
effect
or the spar hole flexing downwards relative to the pin hole in the seat
back.
Rgds.,
Duncan McF.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of G-IANI
Sent: 24 January 2011 12:34
Subject: RE: Europa-List: Re: Main wing bushings
In support of Bud and Pete's notes I can confirm that flexing of the
fuselage is important. The LAA had considerable concerns that the tail
dragger conversion would stiffen the structure in such a way that it
could
lead to overloading of the forward lift pin.
Ian Rickard G-IANI XS Trigear, 300hours
Europa Club Mods Specialist
e-mail g-iani@ntlworld.com
http://www.matronics.com/Navigator?Europa-List
http://forums.matronics.com
http://www.matronics.com/contribution
f="http://www.matronics.com/Navigator?Europa-List"
>http://www.matronics.c=================
======
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Message 13
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Subject: | Re: Main wing bushings |
Phil,
Those with early ("proper"!!) taildraggers were required by LAA to check
that the forward lift pins had not bent, because of suspicion (paranoia?) of
overload in bending. None were found bent. I checked mine again at 300 hours
(still die-straight, but probably hadn't seen more than 2g in flight (and up
to -4g of the wing weight only in landing!).
Also at an earlier time, I measured directly the relative bending stiffness
of the forward lift pin socket/fuselage combination on a number of Europas,
both taildragger, monowheel and one that had not yet had the standard inner
fuselage side stiffener built in. There was a lot of variation in this
stiffness, with the taildragger sockets being stiffer than the standard
build configuration.
However, none were as stiff as the rear (non articulated) sockets of the
original 1300lb MTWA Classic, albeit the rear lift pin only takes about half
of the load of the forward lift pin.
Duncan McF.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of flyingphil2
Sent: 25 January 2011 10:04
Subject: Europa-List: Re: Main wing bushings
All this talk of taildraggers has got me interested now .....
The new owners of Europa use FEA. Also, I believe that they have scanned
some or all of the aircraft. They would therefore be the best people to do
this if they were motivated.
Alternatively, this could be achieved through other channels if they were
prepared to release the CAD data. It's up them really.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=328374#328374
Message 14
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Subject: | Re: Main wing bushings |
Bud,
It sounds like you could 'kill two birds with one stone' by adopting the
design of fuselage reinforcements that the Swiss taildragger uses. If
you've
not seen these I'll send you an isometric sketch.
Duncan McF
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Bud Yerly
Sent: 24 January 2011 23:09
Subject: Re: Europa-List: Re: Main wing bushings
This topic is a moving target, a lot like fiberglass...
Most of the flex of the spars is in the thinner section reaching maximum
nearing the spar socket area. The spar at the root does not move, and
the
forward root rib is really quite stiff, the aft root rib portion is not
as
high so it tends to flex a bit as stated. The fuselage side on the
other
hand is a bit flexi. After repairing a couple aircraft, the aircraft
flexing spots tend to be the area just behind the rudder pedal step,
just
forward of the windscreen on hard landings (when the floor flexes), and
between the front socket and the spar. Interesting thing is the Redux
did
not let go in any of the mishaps. Tough stuff.
Those looking at conventional gear, we must do considerable work to try
to
get the landing gear loads closer to the fuselage sides to carry the
torsional load of the cantilever gear. The cockpit module seat is not
quite
up to the task. To get a proper stance on the gear (read as taller in
height), the moment between the wheel and the fuselage on rough surfaces
is
quite high, and a thin beam gear verses a wider gear beam and the actual
attach mechanism has to be analyzed and tested properly.
All in due time.
Bud
----- Original Message -----
From: Duncan <mailto:ami-mcfadyean@talktalk.net> & Ami
Sent: Monday, January 24, 2011 4:58 PM
Subject: RE: Europa-List: Re: Main wing bushings
<<.. would stiffen the structure in such a way that it could lead to
overloading of the forward lift pin >>
.Ian,
How does that work, if the lift pins are designed to carry the lift
loads in
the first place, there being no greater load available?!
Actually, it was stiffening in bending that might restrain rotation of
the
lift pin that was the issue, resulting in an additional bending load
(not
lift load) being applied to the forward lift pin. The LAA were offered a
spherical socket that would articulate and remove the bending load on
the
pin, but declined to accept that.
However, you are on right path, The earlier discussion in this thread
presumes that the spar flexes, as it indeed doe. But actually the spar
(loaded in this direction) is the least flexible part of the whole
system.
What about the forward and aft portions of the root rib? Let's say these
ribs have equal section and 'I' as the spar, but being laid-up at +/- 45
degrees have x1.41 the elasticity of the unidirectional spar (in the
direction of principal stress), added to which the length of these
flexing
root ribs (between lift pin and spar) is longer than the offset between
lift
pins and spar pins. So, as the root ribs will flex more than the spar
and it
follows that the "leverage" effect between the longitudinal offset of
lift
pin and spar pin centres is removed, or reversed to the extent that the
spar
pins share some lift load.
As you say, the flexing of the fus side also contributes, albeit this
had to
be stiffened-up to prevent pin disengagement.
Previously I have put a small finger down one of the (1/2") spar pin
holes
with the wings rigged, while someone else rather violently loaded the
wing,
albeit not even near to 1g. But there was no hint of the "leverage"
effect
or the spar hole flexing downwards relative to the pin hole in the seat
back.
Rgds.,
Duncan McF.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of G-IANI
Sent: 24 January 2011 12:34
Subject: RE: Europa-List: Re: Main wing bushings
In support of Bud and Pete's notes I can confirm that flexing of the
fuselage is important. The LAA had considerable concerns that the tail
dragger conversion would stiffen the structure in such a way that it
could
lead to overloading of the forward lift pin.
Ian Rickard G-IANI XS Trigear, 300hours
Europa Club Mods Specialist
e-mail g-iani@ntlworld.com
http://www.matronics.com/Navigator?Europa-List
http://forums.matronics.com
http://www.matronics.com/contribution
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Message 15
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Subject: | Re: Main wing bushings |
Duncan=0Amy problem is with the extra load on the lift pins when the spar b
ends, =0Aunnecessary. Maybe the fuse does relax but what's the point of ad
ding a heavy =0Abelt when the braces have enough to do already! =0A=0AGraha
m=0A=0A=0A=0A=0A________________________________=0AFrom: Duncan & Ami <ami-
mcfadyean@talktalk.net>=0ATo: europa-list@matronics.com=0ASent: Tuesday, 25
January, 2011 22:10:16=0ASubject: RE: Europa-List: Re: Main wing bushings
=0A=0A =0AGraham,=0AI agree with all that you say, so unsure why you
=99re not convinced.=0AThe lift load is spread on the wings, but comes to a
point at the lift pins; the =0Astress path being either via the spar and r
oot rib, and/or directly through the =0Awing skin to the root rib (assuming
for the argument no lift contribution from =0Athe spar pins).=0AI recall t
hat when a Europa wing broke in the early tests, it broke across the =0AD-b
ox (LE of wing) adjacent to the rib (and was subsequently reinforced in tha
t =0Aarea).=0AMeaning that this part was overstressed, obviously, but the s
train at failure =0A(being a material constant) was greatest in this part o
f the structure (i.e. up =0Ato the point of failure, the area around the ri
b had flexed more than any other =0Apart of similar =98I).=0A =0A =0A
Duncan.=0A =0A-----Original Message-----=0AFrom: owner-europa-list-server@m
atronics.com =0A[mailto:owner-europa-list-server@matronics.com] On Behalf O
f GRAHAM SINGLETON=0ASent: 24 January 2011 23:20=0ATo: europa-list@matronic
s.com=0ASubject: Re: Europa-List: Re: Main wing bushings=0A =0ANot convince
d Duncan. The spar resists bending and the leverage is enormous, =0Afrom th
e centre of lift of the wing 30% span? The load on the root ribs is shear
=0Aand some bending of the pins. Don't forget the lift load is a spread loa
d =0Awhereas the spar bending of the tangs is a point load applied by the s
par pins.=0AYou are right about the stiffening of the fuselage side. We re
ally should have =0Aflexible sockets at the LE as well as the TE. =0A=0AI
still believe the lift pins (in the root rib) should carry all the lift loa
ds =0Aand the spar pins all the bending loads. That's why the tangs needed
to be =0Astrengthened on the glider.=0A=0AGraham=0A =0A=0A_________________
_______________=0A =0AFrom:Duncan & Ami <ami-mcfadyean@talktalk.net>=0ATo:
europa-list@matronics.com=0ASent: Monday, 24 January, 2011 21:58:21=0ASubje
ct: RE: Europa-List: Re: Main wing bushings=0A<<..would stiffen the structu
re in such a way that it could lead to overloading =0Aof the forward lift p
in>>=0A =0AIan,=0AHow does that work, if the lift pins are designed to carr
y the lift loads in the =0Afirst place, there being no greater load availab
le?!=0AActually, it was stiffening in bending that might restrain rotation
of the lift =0Apin that was the issue, resulting in an additional bending l
oad (not lift load) =0Abeing applied to the forward lift pin. The LAA were
offered a spherical socket =0Athat would articulate and remove the bending
load on the pin, but declined to =0Aaccept that.=0A =0AHowever, you are on
right path, The earlier discussion in this thread presumes =0Athat the spar
flexes, as it indeed doe. But actually the spar (loaded in this =0Adirecti
on) is the least flexible part of the whole system. What about the =0Aforwa
rd and aft portions of the root rib? Let=99s say these ribs have equa
l =0Asection and =98I=99 as the spar, but being laid-up at +/-
45 degrees have x1.41 the =0Aelasticity of the unidirectional spar (in the
direction of principal stress), =0Aadded to which the length of these flexi
ng root ribs (between lift pin and spar) =0Ais longer than the offset betwe
en lift pins and spar pins. So, as the root ribs =0Awill flex more than the
spar and it follows that the =9Cleverage=9D effect between =0A
the longitudinal offset of lift pin and spar pin centres is removed, or rev
ersed =0Ato the extent that the spar pins share some lift load. =0A=0A =0AA
s you say, the flexing of the fus side also contributes, albeit this had to
be =0Astiffened-up to prevent pin disengagement.=0A =0APreviously I have p
ut a small finger down one of the (1/2=9D) spar pin holes with =0Athe
wings rigged, while someone else rather violently loaded the wing, albeit
=0Anot even near to 1g. But there was no hint of the =9Cleverage
=9D effect or the spar =0Ahole flexing downwards relative to the pin hol
e in the seat back.=0A =0ARgds.,=0ADuncan McF.=0A =0A =0A-----Original Mess
age-----=0AFrom: owner-europa-list-server@matronics.com =0A[mailto:owner-eu
ropa-list-server@matronics.com] On Behalf Of G-IANI=0ASent: 24 January 2011
12:34=0ATo: europa-list@matronics.com=0ASubject: RE: Europa-List: Re: Main
wing bushings=0A =0AIn support of Bud and Pete=99s notes I can confi
rm that flexing of the fuselage is =0Aimportant. The LAA had considerable
concerns that the tail dragger conversion =0Awould stiffen the structure in
such a way that it could lead to overloading of =0Athe forward lift pin.
=0A =0A =0AIan Rickard G-IANI XS Trigear, 300hours=0AEuropa Club Mods Speci
alist=0Ae-mail g-iani@ntlworld.com=0A =0A =0A =0A =0A =0Ahttp://www.matroni
cs.com/Navigator?Europa-List=0Ahttp://forums.matronics.com=0Ahttp://www.mat
ronics.com/contribution=0A =0A =0A =0A" target="_blank" href="http://fo
rums.matronics.com">http://forums.matr --> =0A =0Ahttp://www.matronics.co
m/Navigator?Europa-List=0Ahttp://forums.matronics.com=0Ahttp://www.matronic
=========================0A
========================
Message 16
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Subject: | Re: Main wing bushings |
Duncan and Graham,
As for the wing failure point, the idea was to have the actual wing
break before the attachments. Duncan is right, the failure occurs
outboard of the root rib.
I asked why not an articulated forward socket and a proper attach point
with a pin, however a pivoting pinned fitting would then imply that the
forward pin if articulated without a pip pin would slide (not good), as
the pin slides under bending and the forces are not translated due to
the slipping pin I guess. The articulated forward attach was dropped.
I guess since the forward root pin is in shear only, and as long as the
tolerances during wing construction are met, the pin stays fairly
straight, and I am sure under extreme loads, the front pins are pushed
into the socket and with the stiffener added, flexing and failures are
non existent.
The carbon fiber MG spar flexed under load and the more brittle carbon
shear web cracked near the outboard wing pin. So the idea Dave and I
talked about was simple, there is a bit too much taper in the spar tang
and the height of the spar needed to be increased or said another way,
the spar now has less taper. It is now massively strong.
I prefer the common way of distributing that stress concentration at the
rib where the upper skin can collapses under the rib bending, and that
is put in a span wise beam or spar to distribute the point load on the
rib. The attach point is a horizontal bolt or pin in a proper spar.
Also I prefer the beam to go through the fuselage caring the load. Of
course it is that much more stuff to build.
That said, I am amazed this little airplane has soldiered on without
that forward socket ever failing, or the pins. I guess it all works
together without the fancy computer programs or stress analysis
diagnostic programs or even my original skepticism. The combined
attachment points keep things intact extremely well. I was impressed by
the latest glider wing tests done by the factory. On the first test the
rear pin broke because they grabbed a plain steel one used in shop
alignment work and it snapped like a twig. The rear root pin was
replaced and one of the guys in haste put a common bolt in the main wing
and it sheared like butter. Once all the proper pins were correctly
installed (and much egg removed from faces, I'm sure}, the wing with the
spar mod went to nearly 9 G's, finally failing in the leading edge D
tube area when the upper skin flexed until it collapsed. Not a bit of
damage or problem with any of the sockets or the proper wing pins or
bushings.
So, it works brilliantly and is extremely tough at current load limits
imposed. I like it.
Bud
----- Original Message -----
From: Duncan & Ami<mailto:ami-mcfadyean@talktalk.net>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Tuesday, January 25, 2011 5:10 PM
Subject: RE: Europa-List: Re: Main wing bushings
Graham,
I agree with all that you say, so unsure why you're not convinced.
The lift load is spread on the wings, but comes to a point at the lift
pins; the stress path being either via the spar and root rib, and/or
directly through the wing skin to the root rib (assuming for the
argument no lift contribution from the spar pins).
I recall that when a Europa wing broke in the early tests, it broke
across the D-box (LE of wing) adjacent to the rib (and was subsequently
reinforced in that area).
Meaning that this part was overstressed, obviously, but the strain at
failure (being a material constant) was greatest in this part of the
structure (i.e. up to the point of failure, the area around the rib had
flexed more than any other part of similar 'I).
Duncan.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of GRAHAM
SINGLETON
Sent: 24 January 2011 23:20
To: europa-list@matronics.com
Subject: Re: Europa-List: Re: Main wing bushings
Not convinced Duncan. The spar resists bending and the leverage is
enormous, from the centre of lift of the wing 30% span? The load on the
root ribs is shear and some bending of the pins. Don't forget the lift
load is a spread load whereas the spar bending of the tangs is a point
load applied by the spar pins.
You are right about the stiffening of the fuselage side. We really
should have flexible sockets at the LE as well as the TE.
I still believe the lift pins (in the root rib) should carry all the
lift loads and the spar pins all the bending loads. That's why the tangs
needed to be strengthened on the glider.
Graham
-------------------------------------------------------------------------
-----
From: Duncan & Ami <ami-mcfadyean@talktalk.net>
To: europa-list@matronics.com
Sent: Monday, 24 January, 2011 21:58:21
Subject: RE: Europa-List: Re: Main wing bushings
<<.. would stiffen the structure in such a way that it could lead to
overloading of the forward lift pin >>
Ian,
How does that work, if the lift pins are designed to carry the lift
loads in the first place, there being no greater load available?!
Actually, it was stiffening in bending that might restrain rotation of
the lift pin that was the issue, resulting in an additional bending load
(not lift load) being applied to the forward lift pin. The LAA were
offered a spherical socket that would articulate and remove the bending
load on the pin, but declined to accept that.
However, you are on right path, The earlier discussion in this thread
presumes that the spar flexes, as it indeed doe. But actually the spar
(loaded in this direction) is the least flexible part of the whole
system. What about the forward and aft portions of the root rib? Let's
say these ribs have equal section and 'I' as the spar, but being laid-up
at +/- 45 degrees have x1.41 the elasticity of the unidirectional spar
(in the direction of principal stress), added to which the length of
these flexing root ribs (between lift pin and spar) is longer than the
offset between lift pins and spar pins. So, as the root ribs will flex
more than the spar and it follows that the "leverage" effect between the
longitudinal offset of lift pin and spar pin centres is removed, or
reversed to the extent that the spar pins share some lift load.
As you say, the flexing of the fus side also contributes, albeit this
had to be stiffened-up to prevent pin disengagement.
Previously I have put a small finger down one of the (1/2") spar pin
holes with the wings rigged, while someone else rather violently loaded
the wing, albeit not even near to 1g. But there was no hint of the
"leverage" effect or the spar hole flexing downwards relative to the pin
hole in the seat back.
Rgds.,
Duncan McF.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of G-IANI
Sent: 24 January 2011 12:34
To: europa-list@matronics.com
Subject: RE: Europa-List: Re: Main wing bushings
In support of Bud and Pete's notes I can confirm that flexing of the
fuselage is important. The LAA had considerable concerns that the tail
dragger conversion would stiffen the structure in such a way that it
could lead to overloading of the forward lift pin.
Ian Rickard G-IANI XS Trigear, 300hours
Europa Club Mods Specialist
e-mail g-iani@ntlworld.com
http://www.matronics.com/Navigator?Europa-List<http://www.matronics.com/N
avigator?Europa-List>http://forums.matronics.com<http://forums.matronics.
com/>http://www.matronics.com/contribution<http://www.matronics.com/contr
ibution> " target="_blank"
href="http://forums.matronics.com">http://forums.matr -->
<http://www.matronic=======%0d%0a%0d%0a%3c/font%3e%3c/b%3e%
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Message 17
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Subject: | Re: Main wing bushings |
Already being done sir.
bud
----- Original Message -----
From: Duncan & Ami<mailto:ami-mcfadyean@talktalk.net>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Tuesday, January 25, 2011 5:28 PM
Subject: RE: Europa-List: Re: Main wing bushings
Bud,
It sounds like you could 'kill two birds with one stone' by adopting
the design of fuselage reinforcements that the Swiss taildragger uses.
If you've not seen these I'll send you an isometric sketch.
Duncan McF
-----Original Message-----
From:
owner-europa-list-server@matronics.com<mailto:owner-europa-list-server@ma
tronics.com> [mailto:owner-europa-list-server@matronics.com] On Behalf
Of Bud Yerly
Sent: 24 January 2011 23:09
To: europa-list@matronics.com
Subject: Re: Europa-List: Re: Main wing bushings
This topic is a moving target, a lot like fiberglass...
Most of the flex of the spars is in the thinner section reaching
maximum nearing the spar socket area. The spar at the root does not
move, and the forward root rib is really quite stiff, the aft root rib
portion is not as high so it tends to flex a bit as stated. The
fuselage side on the other hand is a bit flexi. After repairing a
couple aircraft, the aircraft flexing spots tend to be the area just
behind the rudder pedal step, just forward of the windscreen on hard
landings (when the floor flexes), and between the front socket and the
spar. Interesting thing is the Redux did not let go in any of the
mishaps. Tough stuff.
Those looking at conventional gear, we must do considerable work to
try to get the landing gear loads closer to the fuselage sides to carry
the torsional load of the cantilever gear. The cockpit module seat is
not quite up to the task. To get a proper stance on the gear (read as
taller in height), the moment between the wheel and the fuselage on
rough surfaces is quite high, and a thin beam gear verses a wider gear
beam and the actual attach mechanism has to be analyzed and tested
properly.
All in due time.
Bud
----- Original Message -----
From: Duncan & Ami<mailto:ami-mcfadyean@talktalk.net>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Monday, January 24, 2011 4:58 PM
Subject: RE: Europa-List: Re: Main wing bushings
<<.. would stiffen the structure in such a way that it could lead to
overloading of the forward lift pin >>
.Ian,
How does that work, if the lift pins are designed to carry the lift
loads in the first place, there being no greater load available?!
Actually, it was stiffening in bending that might restrain rotation
of the lift pin that was the issue, resulting in an additional bending
load (not lift load) being applied to the forward lift pin. The LAA were
offered a spherical socket that would articulate and remove the bending
load on the pin, but declined to accept that.
However, you are on right path, The earlier discussion in this
thread presumes that the spar flexes, as it indeed doe. But actually the
spar (loaded in this direction) is the least flexible part of the whole
system. What about the forward and aft portions of the root rib? Let's
say these ribs have equal section and 'I' as the spar, but being laid-up
at +/- 45 degrees have x1.41 the elasticity of the unidirectional spar
(in the direction of principal stress), added to which the length of
these flexing root ribs (between lift pin and spar) is longer than the
offset between lift pins and spar pins. So, as the root ribs will flex
more than the spar and it follows that the "leverage" effect between the
longitudinal offset of lift pin and spar pin centres is removed, or
reversed to the extent that the spar pins share some lift load.
As you say, the flexing of the fus side also contributes, albeit
this had to be stiffened-up to prevent pin disengagement.
Previously I have put a small finger down one of the (1/2") spar pin
holes with the wings rigged, while someone else rather violently loaded
the wing, albeit not even near to 1g. But there was no hint of the
"leverage" effect or the spar hole flexing downwards relative to the pin
hole in the seat back.
Rgds.,
Duncan McF.
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of G-IANI
Sent: 24 January 2011 12:34
To: europa-list@matronics.com
Subject: RE: Europa-List: Re: Main wing bushings
In support of Bud and Pete's notes I can confirm that flexing of the
fuselage is important. The LAA had considerable concerns that the tail
dragger conversion would stiffen the structure in such a way that it
could lead to overloading of the forward lift pin.
Ian Rickard G-IANI XS Trigear, 300hours
Europa Club Mods Specialist
e-mail g-iani@ntlworld.com
http://www.matronics.com/Navigator?Europa-Listhttp://forums.matronics.com
http://www.matronics.com/contribution
href="http://www.matronics.com/Navigator?Europa-List">http://www.matron
href="http://forums.matronics.com">http://forums.matronics.comhref="h
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