Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Accident
Goto page Previous 1, 2, 3, 4, 5, 6, 7, 8 Next

Matronics Email Lists Forum Index -> Zenith-List

View previous topic :: View next topic

Author Message

planecrazydld(at)yahoo.co
Guest

Posted: Fri Mar 14, 2008 2:26 am Post subject: Accident

jmaynard

Joined: 27 Feb 2008
Posts: 394
Location: Fairmont, MN (FRM)

Posted: Fri Mar 14, 2008 3:40 am Post subject: Accident

On Fri, Mar 14, 2008 at 02:32:47AM -0700, steveadams wrote:

 	  Quote: 	
		   Hey, when it comes to something like this, do the armchair designers

 really want the truth, or would they rather cling to their preconceived

 notions? It doesn't matter that the wings showed almost no torsion at all

 and no failure at the ultimate load in testing or that the latest accident

 was not a structural failure. The notion that there is a problem has taken

 a life of its own regardless of fact or reason.


	


I can't speak for the others who are being taken to task here by several

posters, but as for me, i just want to know the plain, unvarnished truth.

I'll accept that the Australian accident was likely not due to structural

failure. The British one was, at least in part. What about the one in Spain?

(FWIW, I've been to Madrid twice on business, and like the place.) What

about the AMD aircraft in California? (See the list archives for 11 November

2006 for the NTSB preliminary report...though I do wonder why they haven't

issued a final report 16 months later.) That one would be very hard to blame

on construction issues.



The real world trumps theory every time. If it's a problem with the

aircraft's structural design, especially one that would not be revealed by

static testing, then I want to know so I can keep tabs on a fix. If it's a

problem with how the plane is flown, I want to know so I can avoid doing

that. If it's some other kind of problem, I want to know so I can see that

it doesn't affect me or my aircraft.



I don't think it's a common problem, or one that is easy to encounter, or

else there would be more than the 35 accidents in the NTSB database (across

all models of the CH601). I'm not nervous about getting mine and going

flying. Even so, I want to know the truth. That's all.

-- 

Jay Maynard, K5ZC                   http://www.conmicro.com

http://jmaynard.livejournal.com      http://www.tronguy.net

Fairmont, MN (FRM)                        (Yes, that's me!)

AMD Zodiac CH601XLi N55ZC (getting ready to order)

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

steveadams

Joined: 10 Jan 2006
Posts: 191

Posted: Fri Mar 14, 2008 4:26 am Post subject: Re: Accident

I am not taking anyone to task for being concerned and wanting more information. What I have a problem with are a few posters who already have in their minds decided that; 1. there is a definite structural problem, 2. that they know where in the wing the structural problem exists, and 3. have designed fixes for this imaginary problem without any basis in fact, scientific evidence, or even real theoretical analysis to back any of it up. I could say that the failures were due to the builders using blue scotchbrite pads and have as much factual and scientific basis as anything anyone else has proposed. I don't even have a dog in this fight, I have no plans to ever fly a 601. You have to have trust in your aircrafts design. If not you need to either do everything necessary in your mind to achieve that level of trust based on facts and science, or find a design you can trust.

planes_by_ken(at)bellsout
Guest

Posted: Fri Mar 14, 2008 6:18 am Post subject: Accident

I am giving thought to installing diagonal ribs between the stock ones.  

I seem to remember that diagonal ribs are good in torsion.  The Ercoupe 

uses this design.  Be careful or random strengthening as this could 

shift loads to other areas and cause more problems. 

What I would like to know is if they had wing lockers, what type of 

aileron hinge and how much attention was given to aileron rigging 

especially cable tension.

Ken Lilja



ashontz wrote:

 	  Quote: 	
		   



 I agree. The wings are plenty strong in static load. Dynamically, I'm not so sure. Extra ribs provide extra torsional stability and strength, as well as actually making the wings stronger in a pure positive or negative load. Shorter segments to transmit the same load across equals less leverage to crumple the skins, particularly in compression. Think of a 5' fishing pole with only one eye at the very end of the pole. Now think of the same pole with an eye every 6 inches. Much stronger under load.



 I would guess that if you could stand next to that inverted Zenith wing when it was being static tested, and just touched it, it would hobble and bobble all over the place, possibly even notice a bit of a "slow motion flutter".

Jaybannist(at)cs.com
Guest

Posted: Fri Mar 14, 2008 6:44 am Post subject: Accident

Ken,



Exactly what known problem are you thinking about solving?



Jay in Dallas



Ken Lilja <planes_by_ken(at)bellsouth.net> wrote:



 	  Quote: 	
		  



I am giving thought to installing diagonal ribs between the stock ones.  

I seem to remember that diagonal ribs are good in torsion.  The Ercoupe 

uses this design.  Be careful or random strengthening as this could 

shift loads to other areas and cause more problems. 

What I would like to know is if they had wing lockers, what type of 

aileron hinge and how much attention was given to aileron rigging 

especially cable tension.

Ken Lilja



ashontz wrote:

> 

>

> I agree. The wings are plenty strong in static load. Dynamically, I'm not so sure. Extra ribs provide extra torsional stability and strength, as well as actually making the wings stronger in a pure positive or negative load. Shorter segments to transmit the same load across equals less leverage to crumple the skins, particularly in compression. Think of a 5' fishing pole with only one eye at the very end of the pole. Now think of the same pole with an eye every 6 inches. Much stronger under load.

>

> I would guess that if you could stand next to that inverted Zenith wing when it was being static tested, and just touched it, it would hobble and bobble all over the place, possibly even notice a bit of a "slow motion flutter".

>

n85ae

Joined: 14 Mar 2007
Posts: 403

Posted: Fri Mar 14, 2008 7:23 am Post subject: Re: Accident

If I had load tested that wing, in the photo's. The last photo in the series

would have been the broken wing. That's what is missing in my opinion.

A lot can be learned from testing to complete failure.



Jeff.

Gig Giacona

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

Posted: Fri Mar 14, 2008 7:24 am Post subject: Re: Accident

How do you propose to test this new design? Are you going to stress it as the Zenith design as been stressed?



 	  planes_by_ken(at)bellsout wrote: 	
		  I am giving thought to installing diagonal ribs between the stock ones.  

I seem to remember that diagonal ribs are good in torsion.  The Ercoupe 

uses this design.  Be careful or random strengthening as this could 

shift loads to other areas and cause more problems. 

What I would like to know is if they had wing lockers, what type of 

aileron hinge and how much attention was given to aileron rigging 

especially cable tension.

Ken Lilja

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

steveadams

Joined: 10 Jan 2006
Posts: 191

Posted: Fri Mar 14, 2008 7:57 am Post subject: Re: Accident

Do any of the armchair designers have an understanding of doing static testing on a wing? When you see those pictures of wings piled high with sandbags, do you ask yourself just how they decided to place the weight were they did? I'm no engineer, but I can read. Perhaps this might educate some as much as it did me.  A friend who is an engineer sent me the following. I'm sorry I don't have the referenced figures......

_________________________________________________________



The total load that the wing must support is: 



the weight of the aircraft 

multiplied by the load factor (in this case, the 3.8Gs necessary to qualify the airplane for the "Standard" category) 

plus or minus the tail load for a particular flight condition (the center of gravity location was varied from most forward to most aft to determine the tail load to add [or subtract] from the wing load.) 

 



Thatâ€™s the total load. Now, how the load is distributed across the wing varies with the flight condition. Speed, angle of attack and control surface deflection all contribute to variations in distribution. It might be possible to put an unacceptable strain on one point of the wing without exceeding the total load. Loads are not constant from root to tip, nor from leading edge to trailing edge. From all the flight loads considered, we select three "worst case" load conditions to test. If the wing is strong enough to survive these loads, then it will be strong enough in all the other flight conditions.



The first test case:



This is the result of a 3.8G symmetrical pull-up at 10 percent over redline airspeed. The wing angle of attack (AOA) for this case is 5 degrees. When the worst case tail download is considered, this puts the largest total load on the wing/center section and imposes the "worst-case" total bending load that the wing must carry. We design the wings to meet the standards of FAR Part 23 where this case is labeled "Condition D" so we have adopted the same terminology. You can get an idea of the spanwise load distribution for this case in Curve 1 of Fig. 2.



 Chordwise distribution is shown on Fig. 4.  Notice that the majority of the load on the forward one third of the chord.



The second test case that we selected corresponds to Condition A, (again, an FAA label we have adopted) the upper left corner of the envelope shown in Fig 1. This would result from a 3.8G symmetrical pull-up at maneuvering speed. While this is not the worst-case total load, it occurs at a 15 degree angle of attack. The spanwise distribution is shown on the upper curve of Fig. 2, but the interesting stuff happens elsewhere. At this AOA, the load on the wing forces it forward as well as lifting perpendicular to the chord plane. This results in a tension load on the joint between the rear spar and the fuselage. The chordwise load distribution for Condition A is shown in Fig. 3, where we can see that this condition results in most of the load being applied very near the front of the wing, which tries to twist the leading edge up. In engineerspeak it "places a large leading-edge-up torsional load on the wing." The wing is subjected to bending in two planes (forward and up) and twisting at the same time.



The third test case we selected corresponds to a symmetrical pull-up at two thirds of 3.8G at maneuvering speed plus full trailing-edge-down aileron deflection. You canâ€™t read this case directly off the V-n diagram, but it is a good example of how combinations of loads must be considered. The wing angle of attack for this case is 10 degrees. The load for this condition is centered quite forward on the chord of the non-aileron portion of the wing (Fig. 3). The additional lift due to aileron deflection on the outboard portion of the wing (see the lower curve on Fig. 2) places a large bending load on the outboard wing. Because this lift is centered further aft (Fig. 5) it exerts a large trailing-edge-up twist as well.



We obviously canâ€™t duplicate a dynamic situation in the shop, so we have to figure out the load distribution and simulate it with simple weight. If you superimpose the spanwise and chordwise load distributions on top of each other, you end up with a reasonably accurate picture of the total distribution of load over the entire wing root to tip and leading edge to trailing edge.



_________________________________________________________

daveaustin2(at)primus.ca
Guest

Posted: Fri Mar 14, 2008 8:03 am Post subject: Accident

Just a reminder..  it was the centre section of the spar that appeared to be 

the weakest link in the UK crash..

Dave Austin  601HDS - 912, Spitfire Mk VIII

thesumak(at)aol.com
Guest

Posted: Fri Mar 14, 2008 8:17 am Post subject: Accident

In the May 10, 2007 letter, Chris Heintz warned us about the serious damage potential of rapid full forward stick movement at cruise speed.  This is due to the large amount of elevator control which was designed in to have enough elevator authority to provide control for flights made with improper center of gravity computations.  Given what has happened over the last couple of years, it may be wise to re think that design philosophy.  It would seem reasonable to limit elevator control to make rapid full stick movement at cruise a little less apt to rip the wings off and live with the compromised improper center of gravity maneuverability.

     

    With regard to the recent posts that we should stop talking about this, hereâ€™s one vote that everyone has a right to express their opinion on this list.  I donâ€™t think itâ€™s that hard to separate the wheat from the chaff.

     

    Cheers,

    Bill

   Supercharge your AIM. Get the AIM toolbar for your browser. 

  [quote][b]

zenith601xl(at)gmail.com
Guest

Posted: Fri Mar 14, 2008 8:43 am Post subject: Accident

Gig Giacona

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

Posted: Fri Mar 14, 2008 8:48 am Post subject: Re: Accident

I was with you until you used the phrase "It would seem reasonable to limit elevator control ...less apt to rip the wings off ..." 



I don't know about you but I just might like to have that elevator control when flying slow. I think a better answer would be to fly the aircraft in a manner that doesn't over stress the design. I've been flying for over 30 years and I have never felt the need to push full forward on the stick while at cruise speed. 



There are lots of certified aircraft that have issues in certain flight parameters. The answer is usually training or simply putting a sign in the cockpit or the writing something in the POH. Or even in some cases regulation. Google Special Federal Aviation Regulation No. 73.



And no one that I have seen has said anything about not talking about these issues. The problem I and some of the others on the list is people who no not what they hell they are talking about coming up with "Fixes" for a problem that might or might not even be there.



In fact the only messages I've seen posted with the aim to limit a writer's "right to express their opinion" have come from those who have posted fixes and were later admonished for it being a bad idea.



I'm just glad it's Friday which means I'm going to have 2 days in a row to go work on my "death trap to be" with weather that is supposed to be sunny and in the mid 70's. Eat your heart out Northerners.  



[quote="thesumak(at)aol.com"]In the May 10, 2007 letter, Chris Heintz warned us about the serious damage potential of rapid full forward stick movement at cruise speed.  This is due to the large amount of elevator control which was designed in to have enough elevator authority to provide control for flights made with improper center of gravity computations.  Given what has happened over the last couple of years, it may be wise to re think that design philosophy.  It would seem reasonable to limit elevator control to make rapid full stick movement at cruise a little less apt to rip the wings off and live with the compromised improper center of gravity maneuverability.

     

    With regard to the recent posts that we should stop talking about this, hereâ€™s one vote that everyone has a right to express their opinion on this list.  I donâ€™t think itâ€™s that hard to separate the wheat from the chaff.

     

    Cheers,

    Bill

   Supercharge your AIM. Get the AIM toolbar for your browser. 

   	  Quote: 	
		  [b]

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

larry(at)macsmachine.com
Guest

Posted: Fri Mar 14, 2008 10:53 am Post subject: Accident

Ken,

I have to add something here. The idea that you should redesign the 

wings, ribs or anything else is wrong. 

There is no proven fault in the design and the accidents are more likely 

the cause of poor assembly,

construction errors or flying error.  If you redesign the rib structure, 

you become responsible and

you can increase the problem you sought to resolve.  Structures have 

long and short coupled deflections

that permit progressive flexing from the outer panels to the inner.  If 

you make the wing too rigid, you bring

force and stresses to the fuselage and structure more quickly that can 

exceed the design.  I'd recommend

you build and respect the plans before considering those changes and 

talk with the designer or Nick

before doing so.

My recommendation would be to keep faith with the plans.  My hunch is 

that something outside of the

design will be found that links common problem variations to something 

outside the scope of the plans.



If you want to fund a "finite element design review", send the money to 

Zenith to support the most important

source of information you have.  I'm sure this kind of response would be 

appreciated and say we're all in this together.



Larry McFarland 601HDS at www.macsmachine.com

Jaybannist(at)cs.com wrote:

 	  Quote: 	
		   



 Ken,



 Exactly what known problem are you thinking about solving?



 Jay in Dallas



 Ken Lilja <planes_by_ken(at)bellsouth.net> wrote:

 



 I am giving thought to installing diagonal ribs between the stock ones.  

 I seem to remember that diagonal ribs are good in torsion.  The Ercoupe 

 uses this design.  

   

     Ken Lilja
	


 	  Quote: 	
		     

>

planecrazydld(at)yahoo.co
Guest

Posted: Fri Mar 14, 2008 10:57 am Post subject: Accident

I have to ask: does the Cirrus use anti servo tabs? The Thorp T-18 that I used to fly did and the control resistance was progressive.



Sabrina <chicago2paris(at)msn.com> wrote:[quote] --> Zenith-List message posted by: "Sabrina" 



If you look at my interior, I have the sticks coming up through a â€œstopâ€ quadrant.   Even though I have external control surface stops, I also have these internal stops that stop before full deflection but can be flexed to full deflection.   So too, I used kangaroo boots.   For extreme forward or rearward movement, the skins must stretch one side and crunch up on the other side.   This causes increasing resistance as you push full forward or full back, etc.   There is little resistance in 50% of movement, increasing for the next 25% and increasing further the last 25%.  The first time  [quote][b]

thesumak(at)aol.com
Guest

Posted: Fri Mar 14, 2008 2:57 pm Post subject: Accident

Thanks for your response Gig.   From what Rick and Mark say, it appears that the Zenith folks do not share in your ambivalence concerning a possible problem with elevator authority in the XL.   I canâ€™t predict the future, but I would not be surprised if Zenith offers a mod that is something along the lines of what Sabrina has already done on her own.

     

    Cheers,

    Bill

   Supercharge your AIM. Get the AIM toolbar for your browser. 

  [quote][b]

steveadams

Joined: 10 Jan 2006
Posts: 191

Posted: Fri Mar 14, 2008 4:09 pm Post subject: Re: Accident

Every airplane has a Va speed, usually significantly less than normal cruise speed. Something like an anti-servo tab as is on the 640 may make some sense to make it more difficult to force severe elevator deflections at higher speeds. However, you could create new problems at lower speeds by simply limiting elevator travel. Like any other plane, just fly within the envelope rather than trying to change the envelope to match one parameter of how you want to fly.

planes_by_ken(at)bellsout
Guest

Posted: Fri Mar 14, 2008 8:54 pm Post subject: Accident

The "problems"  */I/* mentioned could  be the results of poor or 

inappropriate  modifications, inspection or repairs. 

When does a problem become "Known"?  I picked up the wreckage of a 

Bellanca Decathlon that shed a wing while practicing aerobatics.  The 

wing failure had nothing to do with the wing design, mounting or the way 

that it was flown at the time.  The root problem was a small crack in 

the pilot's seat back, under the glued down upholstery.  No one had been 

looking there.  See NTSB report CHI88FA240,  AD 76-22-01,  AD 89-18-06. 

When did this problem become "Known"  1976?  1989?

We have a couple of incidents where the wing allegedly failed.  Evidence 

has not allowed a conclusion for the cause to be determined. 

Personally, discussion and intelligent thought, and God forbid, putting 

forth a "theory" are not necessarily a bad idea.  We need to remember 

that a "theory" is just a possible explanation for a certain set of 

facts, not a conclusion, not a truth and not an accusation.

Yes, we should let the experts do their work.  But the expert is not 

always the one who discovers the problem, it's cause or sometimes the 

fix.  Sometimes it is the lowly mechanic.  Try asking the FAA a question 

and they very likely will first ask "what do you think"  Ask Cessna to 

approve a repair and the best you get is a "letter of no objection"  

(1983 - 1999)

Ballistic parachutes:  Our new instructor (a former student of mine) 

rode a Cirrus down by parachute after an aileron departed the aircraft.  

He does not feel that he would have survived without it.  I will install 

one.

Back to lurking in my classroom where I will continue to teach my A&P 

students to suspect everything until proven airworthy.

Sorry for ranting,

Ken Lilja

Jaybannist(at)cs.com wrote:

 	  Quote: 	

 Ken,

 Exactly what known problem are you thinking about solving?

 Jay in Dallas

 Ken Lilja <planes_by_ken(at)bellsouth.net> wrote:

> 

>

> I am giving thought to installing diagonal ribs between the stock ones.  

> I seem to remember that diagonal ribs are good in torsion.  The Ercoupe 

> uses this design.  Be careful or random strengthening as this could 

> shift loads to other areas and cause more problems. 

> What I would like to know is if they had wing lockers, what type of 

> aileron hinge and how much attention was given to aileron rigging 

> especially cable tension.

> Ken Lilja

>

> ashontz wrote:

>     

>> 

>>

>> I agree. The wings are plenty strong in static load. Dynamically, I'm not so sure. Extra ribs provide extra torsional stability and strength, as well as actually making the wings stronger in a pure positive or negative load. Shorter segments to transmit the same load across equals less leverage to crumple the skins, particularly in compression. Think of a 5' fishing pole with only one eye at the very end of the pole. Now think of the same pole with an eye every 6 inches. Much stronger under load.

>>

>> I would guess that if you could stand next to that inverted Zenith wing when it was being static tested, and just touched it, it would hobble and bobble all over the place, possibly even notice a bit of a "slow motion flutter".

>>

>>

>>   

>>       

>

planes_by_ken(at)bellsout
Guest

Posted: Fri Mar 14, 2008 9:48 pm Post subject: Accident

Yes, IF I did the modification I would stress test with sandbags on a proof wing.  I did stress testing on a few mods I designed to certified aircraft (field approval 337).  THINKING about a mod is not the same as doing it.  THINKING about a mod is probably the best way to avoid making a mod.  Also, any change is a new design.  Reinforced cabin step attach might effect the rear spar attach.  How about a swing down instrument panel?  Access panels in any new location?  They all could have unintended adverse effects.

 Ken Lilja

 

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



How do you propose to test this new design? Are you going to stress it as the Zenith design as been stressed?





planes_by_ken(at)bellsout wrote:

        	  Quote: 	
		  I am giving thought to installing diagonal ribs between the stock ones.  

I seem to remember that diagonal ribs are good in torsion.  The Ercoupe 

uses this design.  Be careful or random strengthening as this could 

shift loads to other areas and cause more problems. 

What I would like to know is if they had wing lockers, what type of 

aileron hinge and how much attention was given to aileron rigging 

especially cable tension.

Ken Lilja



    	
   

  	
 [b]

planes_by_ken(at)bellsout
Guest

Posted: Fri Mar 14, 2008 10:02 pm Post subject: Accident

Larry,

I am very aware of the issues of propagation of stresses in a 

structure.  My origional post also had this line:  "Be careful or random 

strengthening as this could shift loads to other areas and cause more 

problems."  "Thinking" = "Thought experiment"  I have picked up too many 

aircraft wrecks and had some friends die.  I am very conservative in how 

I will build my 601.

Ken Lilja



LarryMcFarland wrote:

 	  Quote: 	
		   

 Ken,

 I have to add something here. The idea that you should redesign the 

 wings, ribs or anything else is wrong. There is no proven fault in the 

 design and the accidents are more likely the cause of poor assembly,

 construction errors or flying error.  If you redesign the rib 

 structure, you become responsible and

 you can increase the problem you sought to resolve.  Structures have 

 long and short coupled deflections

 that permit progressive flexing from the outer panels to the inner.  

 If you make the wing too rigid, you bring

 force and stresses to the fuselage and structure more quickly that can 

 exceed the design.  I'd recommend

 you build and respect the plans before considering those changes and 

 talk with the designer or Nick

 before doing so.

 My recommendation would be to keep faith with the plans.  My hunch is 

 that something outside of the

 design will be found that links common problem variations to something 

 outside the scope of the plans.



 If you want to fund a "finite element design review", send the money 

 to Zenith to support the most important

 source of information you have.  I'm sure this kind of response would 

 be appreciated and say we're all in this together.



 Larry McFarland 601HDS at www.macsmachine.com

n801bh(at)netzero.com
Guest

Posted: Sat Mar 15, 2008 2:57 am Post subject: Accident

Thanks Ken for your insight..  

Building an experimental plane is a task that is not to be taken lightly. Going the route of others before you is challenging enough but doing what I did, installing a rather large and powerful V-8 in an 801 is almost over the top. I have been racing, modifying, tinkering all my life so I have a pretty good perspective on what might result.On street cars, race cars,race boats and god only knows what else I have tweaked all you have to do if something didn't work out as planned was to be pulled home, into the pits or off the side of the road. On a plane its a life changing experience. !!! So far I feel comfortable I have addressed all the issues that could kill me, and there are a million and one of them that have tried to anticipate. My plane might run another 50 years or it could kill me in the next 50 seconds of flight........ Thats why we call them "EXPERIMENTAL" 

 Push the envelope within reason................ 

do not archive

Ben Haas

N801BH

www.haaspowerair.com



-- Ken Lilja <planes_by_ken(at)bellsouth.net> wrote:

Yes, IF I did the modification I would stress test with sandbags on a proof wing.  I did stress testing on a few mods I designed to certified aircraft (field approval 337).  THINKING about a mod is not the same as doing it.  THINKING about a mod is probably the best way to avoid making a mod.  Also, any change is a new design.  Reinforced cabin step attach might effect the rear spar attach.  How about a swing down instrument panel?  Access panels in any new location?  They all could have unintended adverse effects.

Ken Lilja



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



How do you propose to test this new design? Are you going to stress it as the Zenith design as been stressed?





planes_by_ken(at)bellsout wrote:

   	  Quote: 	
		  I am giving thought to installing diagonal ribs between the stock ones.  

I seem to remember that diagonal ribs are good in torsion.  The Ercoupe 

uses this design.  Be careful or random strengthening as this could 

shift loads to other areas and cause more problems. 

What I would like to know is if they had wing lockers, what type of 

aileron hinge and how much attention was given to aileron rigging 

especially cable tension.

Ken Lilja



    	


  	




====================================

">http://www.matronics.com/Navigator?Zenith-List

====================================

tronics.com

====================================

www.matronics.com/contribution

====================================



	
 



_____________________________________________________________

Put your loved ones in good hands with quality senior assisted living. Click now!

   [quote][b]

Display posts from previous:

	Matronics Email Lists Forum Index -> Zenith-List	All times are GMT - 8 Hours Goto page Previous 1, 2, 3, 4, 5, 6, 7, 8 Next
Page 6 of 8

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum