---------------------------------------------------------- Zenith-List Digest Archive --- Total Messages Posted Thu 04/15/10: 14 ---------------------------------------------------------- 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) ________________________________ Message 1 _____________________________________ Time: 06:39:40 AM PST US From: "n801bh@netzero.com" Subject: Re: Zenith-List: 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" 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 ======================== =========== ======================== =========== ======================== =========== ======================== =========== ____________________________________________________________ Penny Stock Jumping 2000% Sign up to the #1 voted penny stock newsletter for free today! http://thirdpartyoffers.netzero.net/TGL3241/4bc716e81115e31d5ast01vuc ________________________________ Message 2 _____________________________________ Time: 07:49:51 AM PST US Subject: Zenith-List: Re: 601XL main spar question From: "sdthatcher" 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 ________________________________ Message 3 _____________________________________ Time: 07:58:56 AM PST US Subject: Zenith-List: Re: 601XL main spar question From: "sdthatcher" 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 ________________________________ Message 4 _____________________________________ Time: 11:22:05 AM PST US Subject: Zenith-List: Re: 601XL main spar question From: "Sabrina" 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 5 _____________________________________ Time: 11:50:43 AM PST US From: "George Swinford" Subject: Re: Zenith-List: 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" 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 _____________________________________ Time: 12:03:23 PM PST US From: "Paul Mulwitz" Subject: RE: Zenith-List: 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 ________________________________ Message 7 _____________________________________ Time: 12:26:11 PM PST US Subject: Zenith-List: Re: 601XL main spar question From: "Sabrina" 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 ________________________________ Message 8 _____________________________________ Time: 02:40:13 PM PST US Subject: Zenith-List: Re: 601XL main spar question From: "PatrickW" 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 9 _____________________________________ Time: 03:51:35 PM PST US From: MaxNr@aol.com Subject: Zenith-List: 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 ____________________________________ Time: 05:10:18 PM PST US Subject: Zenith-List: Re: 601XL main spar question From: "Sabrina" 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 11 ____________________________________ Time: 09:35:16 PM PST US From: JohnDRead@aol.com Subject: Re: Zenith-List: 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" 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 ____________________________________ Time: 09:36:57 PM PST US From: JohnDRead@aol.com Subject: Re: Zenith-List: 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 ____________________________________ Time: 09:42:37 PM PST US From: JohnDRead@aol.com Subject: Re: Zenith-List: 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" 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 ____________________________________ Time: 10:09:55 PM PST US Subject: Zenith-List: Re: 601XL main spar question From: "Sabrina" 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 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message zenith-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Zenith-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/zenith-list Browse Digests http://www.matronics.com/digest/zenith-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.