Today's Message Index:
----------------------
1. 06:39 AM - Re: Re: 601XL main spar question (n801bh@netzero.com)
2. 07:49 AM - Re: 601XL main spar question (sdthatcher)
3. 07:58 AM - Re: 601XL main spar question (sdthatcher)
4. 11:22 AM - Re: 601XL main spar question (Sabrina)
5. 11:50 AM - Re: Re: 601XL main spar question (George Swinford)
6. 12:03 PM - Re: Re: 601XL main spar question (Paul Mulwitz)
7. 12:26 PM - Re: 601XL main spar question (Sabrina)
8. 02:40 PM - Re: 601XL main spar question (PatrickW)
9. 03:51 PM - Re: 601XL main spar question (MaxNr@aol.com)
10. 05:10 PM - Re: 601XL main spar question (Sabrina)
11. 09:35 PM - Re: Re: 601XL main spar question (JohnDRead@aol.com)
12. 09:36 PM - Re: Re: 601XL main spar question (JohnDRead@aol.com)
13. 09:42 PM - Re: Re: 601XL main spar question (JohnDRead@aol.com)
14. 10:09 PM - Re: 601XL main spar question (Sabrina)
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| Subject: | Re: 601XL main spar question |
No Problem ma''am.... Slow people fly slow airplanes. So , me and my 801
are a perfect match.G>
do not archive
Ben Haas
N801BH
www.haaspowerair.com
---------- Original Message ----------
From: "Sabrina" <chicago2paris@msn.com>
Subject: Zenith-List: Re: 601XL main spar question
Ben, you are so kind... but AL beat you to it... thank you so much for
offering... :O)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294283#294283
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| Subject: | Re: 601XL main spar question |
I've still got mine... from some 40 years ago!
Sabrina wrote:
> P.S. Dear John... a better book than CH's is Bruhn's Analysis & Design of Flight
Vehicle Structures... a little bit more expensive at $100 used (original
cost new was $17 back in the day) but well worth it...
--------
Scott Thatcher, Palm Beach Gardens, FL
601XL with Corvair, Registered as E-LSA
N601EL, EAA203 42 hours and climbing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294310#294310
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| Subject: | Re: 601XL main spar question |
Sabrina... Is your comment below the reason you felt uneasy about the upgrade?
"Do you think, in a flutter scenario you suggest, the wing fails first in negative
gs?"
--------
Scott Thatcher, Palm Beach Gardens, FL
601XL with Corvair, Registered as E-LSA
N601EL, EAA203 42 hours and holding.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294311#294311
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| Subject: | Re: 601XL main spar question |
Scott,
I would like to poll the members... even the 701 and 801 guys, history has proven
them much 'smarter' than us 601XL gals and guys... :o)
who thinks it is positive G's that are tearing our wings off? (of course the wings
fold upward, but that could be due to the resulting dive or the result of
negative Gs twisting the spar first...)
who thinks it is negative G's?
who thinks it is the horizontal stabilizer is coming loose and causing wing failure?
if it were flutter, would not the wing fail first in negative Gs, and then very
quickly fold up? (does anyone believe the "-6 G @ 1320 lbs." ultimate written
on page 6-X-1 dated 08/05? Isn't it more like +6/-2.4 G utilmate as tested?)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294335#294335
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| Subject: | Re: 601XL main spar question |
Sabrina:
Just a thought here from an old aero engineer: Have you considered that,
if flutter is the problem, the failure mode is quite likely torsion, rather
than bending?
George
----- Original Message -----
From: "Sabrina" <chicago2paris@msn.com>
Sent: Thursday, April 15, 2010 11:20 AM
Subject: Zenith-List: Re: 601XL main spar question
>
> Scott,
>
> I would like to poll the members... even the 701 and 801 guys, history has
> proven them much 'smarter' than us 601XL gals and guys... :o)
>
> who thinks it is positive G's that are tearing our wings off? (of course
> the wings fold upward, but that could be due to the resulting dive or the
> result of negative Gs twisting the spar first...)
>
> who thinks it is negative G's?
>
> who thinks it is the horizontal stabilizer is coming loose and causing
> wing failure?
>
> if it were flutter, would not the wing fail first in negative Gs, and then
> very quickly fold up? (does anyone believe the "-6 G @ 1320 lbs."
> ultimate written on page 6-X-1 dated 08/05? Isn't it more like +6/-2.4 G
> utilmate as tested?)
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=294335#294335
>
>
>
Message 6
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| Subject: | Re: 601XL main spar question |
Hi Sabrina,
I'm afraid nobody knows the answer to your question. If they did then the
cause of the accidents would not be "Unknown".
All we know for sure is that the airframe seems to always fail in the same
place - the joint between the wings and fuselage. You could get more
detailed description of the failure to include exact part numbers, but the
result is the same.
The upgrade blessed by the FAA, Chris, and apparently everyone who has
installed it merely beefs up the whole wing structure. It also balances the
ailerons (as originally demanded by the NTSB). It does nothing to fix the
control sensitivity gradient that the NTSB also asked for.
Any guesses as to the actual failure scenario would be just that -- guesses.
I truly hope you reexamine your decision to design your own fix for this
totally unknown problem. I would sleep a lot better if you either installed
the approved upgrade or just scrapped your plane. I am currently installing
the upgrade in mine, but I will not take it out of phase I testing until a
significant amount of time (perhaps a year) has gone by with no more
structure failures.
I have no doubt that you are very smart and probably the best educated
person on this list. Still, I don't think that is enough to know what is
wrong with the Zodiac XL design and how to fix it.
Best regards,
Paul
Installing XL upgrade
-----Original Message-----
From: owner-zenith-list-server@matronics.com
[mailto:owner-zenith-list-server@matronics.com] On Behalf Of Sabrina
Sent: Thursday, April 15, 2010 11:21 AM
Subject: Zenith-List: Re: 601XL main spar question
Scott,
I would like to poll the members... even the 701 and 801 guys, history has
proven them much 'smarter' than us 601XL gals and guys... :o)
who thinks it is positive G's that are tearing our wings off? (of course
the wings fold upward, but that could be due to the resulting dive or the
result of negative Gs twisting the spar first...)
who thinks it is negative G's?
who thinks it is the horizontal stabilizer is coming loose and causing wing
failure?
if it were flutter, would not the wing fail first in negative Gs, and then
very quickly fold up? (does anyone believe the "-6 G @ 1320 lbs." ultimate
written on page 6-X-1 dated 08/05? Isn't it more like +6/-2.4 G utilmate as
tested?)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294335#294335
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| Subject: | Re: 601XL main spar question |
George...
torsion tearing out the rear spar, sure... but again could the torsion be arrested
with a top mounted cable providing tension or is a rear strut required so
as to provide compression strength as well?
Paul...
please, when you re-install your wings, clean up, maybe ream out and oversize your
main spar bolt holes, it looked like Zenith used a course rat tail file to
make the first set of holes I saw last August...
I agree with you Paul, installing a set of rear spar struts changes everything...
still don't know what to do to overcome the apparent lack of torsional rigidity
in the design... the L angles on the skins don't cut it for me... I am
thinking wire bracing from the bottom of the wing, mid-span rear spar 4130 doubler
to the tail tie down and a top mounted wire brace from mid-span top rear
spar through the fuselage to the other spar...
as for the floating main spar struts, they will be fine tuned during testing...
I am still waiting for CH to supply his final "non-upgrade" numbers as to ultimate
Gs and max gross -- so long as I keep within those parameters during flight
testings, everything should be fine...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294342#294342
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| Subject: | Re: 601XL main spar question |
Sabrina wrote:
> I would like to poll the members...
Torsion.
Take a cardboard shoe box. Tape it up nice and tight. You can stand on it.
Take that same cardboard shoe box. Tape it up nice and tight, but with a 9 degree
tilt to it. Then try to stand on it. Not nearly as strong.
The question is, "do the upgrades make the wing strong enough...?" It appears
that as far as Zenith and the FAA is concerned, the answer is "yes".
Time will tell as more of us complete the upgrades and return to the air.
Patrick
XL/Corvair/BRS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294356#294356
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| Subject: | Re: 601XL main spar question |
A poll? Nobody here kicked tin at the various accident sites. I would
sooner rely on the investigating agencies and not the "experts" who were not
there.
"Tearing our wings off ?" Just about all of the wing failures happened in
cruise flight. Several in the traffic pattern. One purely weather related
case.
"Horizontal stabilizer?" NTSB says that in only one case, the fwd
stabilizer brackets collapsed first, followed by total break up. I was asked to
look
at a project in the area and found the rear bracket cracked. Zero flight
time. A more detailed exam revealed cracks left and right side. I posted
pictures in ZBAG "photos." I am still tying to get my hands on this part. Any
questions, contact me at MaxNr@aol.com.
Questions about flutter are not adequately covered in a few posts on a user
group. Many people "believe" or "don't believe" only as matter of faith. As
for me, I depend on advice from a retired aerodynamicist in my area who
worked on USAF flutter projects. Bingelis has archived lots of flutter stuff on
the EAA website. Barnaby Wainfan recently wrote columns on flutter in
Kitplanes. I also listen a lot to an A.I. who is still a senior inspector at the
carrier that I retired from.
I so wanted to stay out of this, but couldn't resist.
Bob Dingley
601XL Plans 6-6791 Jab 3300 (Formerly a Lyc)
Picking away at the recently arrived upgrade.
Message 10
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| Subject: | Re: 601XL main spar question |
Bob,
You are exactly the person to pull into the discussion... what do your experts
think is being addressed by the factory mods... in other words which failure
mode is being addressed the most with the upgrade according to your sources...
although we each know very little on our own, we all have an expert of two giving
us advice...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294371#294371
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| Subject: | Re: 601XL main spar question |
Pilot error!
Regards, John
CH701 - Colorado - Jabiru 3300
Cell: 719-494-4567
Home: 303-648-3261
In a message dated 4/15/2010 6:27:53 P.M. Mountain Daylight Time,
chicago2paris@msn.com writes:
--> Zenith-List message posted by: "Sabrina" <chicago2paris@msn.com>
Bob,
You are exactly the person to pull into the discussion... what do your
experts think is being addressed by the factory mods... in other words which
failure mode is being addressed the most with the upgrade according to your
sources...
although we each know very little on our own, we all have an expert of two
giving us advice...
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294371#294371
Message 12
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| Subject: | Re: 601XL main spar question |
Thanks Bob, there is some sanity out there!
Regards, John
CH701 - Colorado - Jabiru 3300
Cell: 719-494-4567
Home: 303-648-3261
In a message dated 4/15/2010 4:52:12 P.M. Mountain Daylight Time,
MaxNr@aol.com writes:
A poll? Nobody here kicked tin at the various accident sites. I would
sooner rely on the investigating agencies and not the "experts" who were not
there.
"Tearing our wings off ?" Just about all of the wing failures happened in
cruise flight. Several in the traffic pattern. One purely weather related
case.
"Horizontal stabilizer?" NTSB says that in only one case, the fwd
stabilizer brackets collapsed first, followed by total break up. I was asked to
look at a project in the area and found the rear bracket cracked. Zero flight
time. A more detailed exam revealed cracks left and right side. I posted
pictures in ZBAG "photos." I am still tying to get my hands on this part. Any
questions, contact me at MaxNr@aol.com.
Questions about flutter are not adequately covered in a few posts on a
user group. Many people "believe" or "don't believe" only as matter of faith.
As for me, I depend on advice from a retired aerodynamicist in my area who
worked on USAF flutter projects. Bingelis has archived lots of flutter
stuff on the EAA website. Barnaby Wainfan recently wrote columns on flutter in
Kitplanes. I also listen a lot to an A.I. who is still a senior inspector
at the carrier that I retired from.
I so wanted to stay out of this, but couldn't resist.
Bob Dingley
601XL Plans 6-6791 Jab 3300 (Formerly a Lyc)
Picking away at the recently arrived upgrade.
(http://www.matronics.com/Navigator?Zenith-List)
(http://www.matronics.com/contribution)
Message 13
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| Subject: | Re: 601XL main spar question |
None of you seem to understand what a monocoque structure is and how it
resists both bending and torsion. As I suggested in a recent post - buy a copy
of Chris Heintz book and you will understand. There are other books about
airframe structure design but none written about the Zenith series of
aircraft by the designer.
Regards, John
CH701 - Colorado - Jabiru 3300
Cell: 719-494-4567
Home: 303-648-3261
In a message dated 4/15/2010 3:40:50 P.M. Mountain Daylight Time,
pwhoyt@yahoo.com writes:
--> Zenith-List message posted by: "PatrickW" <pwhoyt@yahoo.com>
Sabrina wrote:
> I would like to poll the members...
Torsion.
Take a cardboard shoe box. Tape it up nice and tight. You can stand on
it.
Take that same cardboard shoe box. Tape it up nice and tight, but with a
9 degree tilt to it. Then try to stand on it. Not nearly as strong.
The question is, "do the upgrades make the wing strong enough...?" It
appears that as far as Zenith and the FAA is concerned, the answer is "yes".
Time will tell as more of us complete the upgrades and return to the air.
Patrick
XL/Corvair/BRS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294356#294356
Message 14
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| Subject: | Re: 601XL main spar question |
John,
The 601HD is an amazing structure... kudos to CH...
I have heard the 601XL compared to a sedan cut down to a convertible without reinforcing
the chassis...
Your pilot error response was funny, I must admit...
Best wishes,
Sabrina
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=294390#294390
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