Today's Message Index:
----------------------
1. 12:02 AM - Re: Cabin Floor and Rudder Pedals (Craig Payne)
2. 03:15 AM - Misinformation, disinformation, and recent accidents (steveadams)
3. 04:10 AM - Re: Cabin Floor and Rudder Pedals (Paul Mulwitz)
4. 04:24 AM - Re: Wing sweep and recent crashes (David Downey)
5. 06:07 AM - Re: Wing sweep and recent crashes (Southern Reflections)
6. 06:30 AM - Re: Appologize (Carlos Sa)
7. 06:33 AM - Fuel system contamination (robert stone)
8. 07:06 AM - Re: Fuel tank cushion strips (LarryMcFarland)
9. 07:07 AM - Wing Sweep (Scott Laughlin)
10. 07:14 AM - Re: Wing sweep and recent crashes (David Mikesell)
11. 07:15 AM - Re: Fuel system contamination (LarryMcFarland)
12. 07:24 AM - Re: Recent crashes (Robert N. Eli)
13. 07:30 AM - New letter from Chris Heintz!! 5/11 (swater6)
14. 07:34 AM - Re: Cabin Floor and Rudder Pedals (Michael Valentine)
15. 07:52 AM - Tow Bar (Timothy Croy)
16. 08:41 AM - misinformation about HD/HDS landing gear (Jeff Small)
17. 08:46 AM - turnbuckles and safety wire (Jeff Small)
18. 08:46 AM - Re: Fuel system contamination (Paul Mulwitz)
19. 08:46 AM - Re: 178 seconds (Tim Juhl)
20. 09:16 AM - Re: New letter from Chris Heintz!! 5/11 (kevinbonds)
21. 09:23 AM - Re: Fuel system contamination (ronlee)
22. 09:30 AM - Re: New letter from Chris Heintz!! 5/11 (Paul Mulwitz)
23. 09:54 AM - Re: Tow Bar (Bill Naumuk)
24. 10:11 AM - Re: Tow Bar (LarryMcFarland)
25. 10:15 AM - Re: turnbuckles and safety wire (Craig Payne)
26. 10:18 AM - Chris's letter (Jerry Hey)
27. 10:24 AM - Re: Tow Bar (Craig Payne)
28. 10:24 AM - Re: Recent crashes (ashontz)
29. 10:29 AM - Re: Recent crashes (ashontz)
30. 10:42 AM - Re: Cabin Floor and Rudder Pedals (Craig Payne)
31. 11:20 AM - Re: Re: 601XL crash in Modesto CA last year ()
32. 11:33 AM - Re: accident ()
33. 11:53 AM - Re: Cabin Floor and Rudder Pedals (David Downey)
34. 01:21 PM - Rolled bead for fuel tank (Maarten Versteeg)
35. 01:46 PM - Re: Rolled bead for fuel tank (Jerry Hey)
36. 02:16 PM - 701 wing strut (Gordon)
37. 02:31 PM - Stab help (Ron Miller)
38. 02:36 PM - Re: Rolled bead for fuel tank (TxDave)
39. 02:48 PM - Re: NTSB search for breakup accidents. (Ron Lendon)
40. 02:55 PM - Re: Fuel system contamination (robert stone)
41. 03:23 PM - Re: Tow Bar (Timothy Croy)
42. 03:37 PM - Re: Stab help (Ron Lendon)
43. 03:46 PM - Re: Rolled bead for fuel tank (Ron Lendon)
44. 04:17 PM - Re: accident (ZodieRocket)
45. 04:45 PM - Re: Re: Rolled bead for fuel tank (David Downey)
46. 05:10 PM - Any Michiganders going to Zenith Zip? (Tim Juhl)
47. 05:16 PM - Re: Stab help (TxDave)
48. 05:20 PM - Re: Stab help (Tim Juhl)
49. 05:34 PM - Re: accident (Tim Juhl)
50. 07:47 PM - Re: Re: Stab help (Craig Payne)
51. 08:50 PM - Re: New letter from Chris Heintz!! 5/11 (Mike Moore)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Cabin Floor and Rudder Pedals |
I may not be clear on what the problem is but would making a custom bearing
remove the need to replace any metal?
-- Craig
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Misinformation, disinformation, and recent accidents |
As a builder of a CH640, I am folloing these accidents with interest, as there
are similar design characteristics of the 640 and 601. Reading through the large
number of posts on these accidents I am amazed. From a need to do structural
testing (been done), inadequate rivets, weak spar caps, dangerous forward swept
wings, weak attach points, Zenith "hiding" a known defect due to liability,
completely backwards disertations on Va speeds and weight, reading things in
the NTSB reports that aren't there, and armchair designers proposed modifications,
the amount of misinformation and disinformation is unbelievable. I only
hope that not many builders use this half baked information to make a bunch of
half baked modifications to a proven, thoroughly tested airframe and then let
an innocent person climb into the right seat.
Steve Adams
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112552#112552
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cabin Floor and Rudder Pedals |
Hi Michael,
I feel your pain. I am just now taking my cabin floor apart for
deburring, painting, and riveting.
I don't think I would bend the steel weldments to make it all fit
together. Firstly, they are very difficult to bend. Secondly, I
don't think they would ride correctly in the bearings if they were bent.
I would probably insist ZAC send me a properly made cabin floor
part. If I wasn't willing to wait, I would drill new holes where
they are actually needed and add reinforcements when the proper edge
distances were not met. The reinforcements might be small washers of
the same weight as the damaged part riveted on the far side or they
might be larger pieces of similar material.
I wish you luck,
Paul
XL fuselage
do not archive
At 08:22 PM 5/12/2007, you wrote:
>Listers - I am done with my firewall (thanks for the help) and on to
>the cabin floor. Unfortunately, some guy on his first day at the
>factory must have made the floor (6B10-1) because it is pretty
>shoddy. The bends of the "wings" are a couple mm off, leading to
>some problems with the centerline and edges in relation to the
>holes. But, so far I have been able to make everything work. Until now.
>
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Wing sweep and recent crashes |
see below
Gary Boothe <gboothe@calply.com> wrote: MAN! With all your theorizing,
conjecturing and armchair quarterbacking, you guys can take a half story
and twist it 9 ways from Sunday! Without knowing anything but a small portion
of the facts you are willing to question the basics of the CH designs!
What I think is really happening, is that some educated people are using this
list to expound their knowledge and education. If you dont like the 601XL designDONT
BUILD IT!! I have built planes before and will continue to build my XL
- with very few alterations in the basic design. I believe that perhaps I have
been looking at the fact that the XL can and will accelerate very rapidly beyond
the skill capability of a pilot with limited experience. Velocity is danger
in a lightly built plane. If the designer were NOT CH, I would have changed
my mind a long time ago.
As for me, I put my $$$ on Mr. Heintz. Im not building an XL, but I happen to
think the airplane is designed as is for a reasona reason I dont understand,
because, if I did, I would design and build my own! Heres a thought: If you dont
understand why the wing is swept forward, maybe Chris Heintz knows more than
you. I have asked the question but have not gotten an answer. I assume that
the wing is that way as a consequence of the angled spar - and I assume that
CH was fully aware of the possibilities. Most likely it was a design compromise
- all of them are.
Dont bother telling me that an intelligent builder should question everything.
Am I willing to just blindly follow? Uh, yeah (see above).
We should all be so willing to "blindly" follow the design when it comes from someone
with the qualification of a CH. Two issues pop out: I am not convinced
that CH did all the design as there are a number of components that do not look
like classic CH. There is also the issue that modern day homebuilders do not
tend to avail themselves of the body of classic knowledge readily at hand that
present issues that no plan set can afford to try and educate on.
My vote is that this is a useless thread that will do little or nothing to help
anyone. ...and I agree. This will be my last post on the issue. I apologize
for offending.
Gary Boothe
Cool, CA
601 HDSTD, WW Conversion 90% done,
Tail done, wings done, working on c-section
Dave Downey
Harleysville (SE) PA
Zodiac 601XL/Corvair?
---------------------------------
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Wing sweep and recent crashes |
David, It's to bad,you're not going to post any more on this sub. I
found it very intresting, and educating,but knowledge and information
can always be replaced by blind fatith , and " I PUTT'S MY MONEY
UP"...Me,I like to hear from people like Klass,Kevin,and your self. I
have a 601Xl ,and the thing that keeps coming up in my mind is what
happened over the "Cooling Tower"and the rash of folding wings,to me it
just doesn't wash. I just don't want to wind up standing in front of St.
Peter or the devil,And they ask me how I got there? and I'll have to
tell them "I drove a 601 XL with NO WINGS.. thanks again for your
input. fly Safe Joe N101HD
----- Original Message ,
From: David Downey
To: zenith-list@matronics.com
Sent: Sunday, May 13, 2007 7:23 AM
Subject: Re: Zenith-List: Wing sweep and recent crashes
see below
Gary Boothe <gboothe@calply.com> wrote:
MAN! With all your theorizing, conjecturing and armchair
quarterbacking, you guys can take a half story and twist it 9 ways from
Sunday! Without knowing anything but a small portion of the facts you
are willing to question the basics of the CH designs!
What I think is really happening, is that some 'educated' people are
using this list to expound their knowledge and education. If you don't
like the 601XL design.DON'T BUILD IT!! I have built planes before and
will continue to build my XL - with very few alterations in the basic
design. I believe that perhaps I have been looking at the fact that the
XL can and will accelerate very rapidly beyond the skill capability of a
pilot with limited experience. Velocity is danger in a lightly built
plane. If the designer were NOT CH, I would have changed my mind a long
time ago.
As for me, I put my $$$ on Mr. Heintz. I'm not building an XL, but I
happen to think the airplane is designed as is for a reason.a reason I
don't understand, because, if I did, I would design and build my own!
Here's a thought: If you don't understand why the wing is swept
forward, maybe Chris Heintz knows more than you. I have asked the
question but have not gotten an answer. I assume that the wing is that
way as a consequence of the angled spar - and I assume that CH was
fully aware of the possibilities. Most likely it was a design
compromise - all of them are.
Don't bother telling me that an 'intelligent' builder should
question everything. Am I willing to just blindly follow? Uh, yeah (see
above).
We should all be so willing to "blindly" follow the design when it
comes from someone with the qualification of a CH. Two issues pop out: I
am not convinced that CH did all the design as there are a number of
components that do not look like classic CH. There is also the issue
that modern day homebuilders do not tend to avail themselves of the body
of classic knowledge readily at hand that present issues that no plan
set can afford to try and educate on.
My vote is that this is a useless thread that will do little or
nothing to help anyone. ...and I agree. This will be my last post on the
issue. I apologize for offending.
Gary Boothe
Cool, CA
601 HDSTD, WW Conversion 90% done,
Tail done, wings done, working on c-section
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Kevin, it happens to others as well.
The text is there, but you need to look at the raw msg to see it.
Cheers
Carlos
On 13/05/07, kevinbonds <kevinbonds@comcast.net> wrote:
>
> Something about the Comcast, Web based mail client seems to sometimes
> remove the body of my emails. I apologize to everyone. I'll stick to
> Outlook.
>
>
> Kevin Bonds
>
> Nashville TN
>
> 601XL Plans building.
>
> http://home.comcast.net/~kevinbonds<http://home.comcast.net/%7Ekevinbonds>
>
>
> do not archive DO NOT ARCHIVE
>
>
> *
>
>
> *
>
>
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Fuel system contamination |
Members,
I have not had my ZodiacXL for very long and was unaware of the
center fuel drain until a friend pointed it out to me. When I opened
the valve nothing but black materiel came out eventually turning green
then finally blue. I have no idea what this materiel was but I suspect
auto fuel. I did not build this aircraft but got it from a man in
Ringwood, Oklahoma and I suspect he used auto fuel to fly the 40 hours
off. Have any of you Zodiac601XL builders had an experence like this
and what action did you take.
Tracy Stone DO NOT ARCHIVE
Zodiac601XL
Harker Heights, Tx
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Fuel tank cushion strips |
Craig,
Cork is a good cushion when little movement is needed. Anything that
causes movement in
cork will eventually crumble cork. Good for pads or insulate, bad for
anything that gets bent
or deformed regularly. Silicone is the way to go for cowl baffle strips.
Larry McFarland at www.macsmachine.com
do not archive
>>
>>> <craig@craigandjean.com>
>>>
>>> What is the advantage of using the cork strips that Zenith specifies
>>> over
>>> silicon rubber (specifically cowling baffle strips). I'm planning the
>>> mounting of my header tank and I have the silicon on-hand.
>>>
>>> Also, if I go that with the cork, what is a good source?
>>>
>>> -- Craig
>>>
>
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Guys:
I've been reading the speculation posted here for the past few days about
the 601 crashes. I know many of you have stayed in a Holiday Inn Express,
but how many of the guys with opinions here have actually installed the
wings on a 601XL and measured the wing sweep?
Last weekend when I was installing my wings, I was confused over this idea,
then a very smart guy helped me figure this out - Dave Miller. Dave is one
of the founding members of our local EAA and is building a 601XL in the
early stages from plans just like I did. In the final stages of building my
601XL, Dave has been a great help. Here's what he helped me understand
about the wings of the XL concerning wing sweep:
As was mentioned earlier, the spar is not vertical when the airplane is
level. If you place a string from wingtip to wingtip across the fuselage
with the canopy open, it will APPEAR that the two rivet lines are sweeping
forward. In other words if you put the string on the end rivet for the spar
cap drop a plumb bob from the center of the string, it will not drop down to
the top of the spar cap on the center spar. Why? Because with the airplane
sitting level, the spar leans forward. You have to either tilt the airplane
backwards so the spar is vertical and use a plum line, or project a line
from the spar along the angle. If you do this, you will see that the wings
don't sweep forward. There is a caveat here:
I had to trim my rear spar tabs on the fuselage to bring the wings back -
this is because the spar tabs were hitting the first rib, causing the wings
to sweep forward a little. I test-fit the flaps before trimming the tabs
and they were crazy-far away from the fuselage so it was a no-brainer to
trim them and move the rear of the wings closer to the fuselage which takes
away the forward-sweep. I cut about 1/4" off the tabs.
I won't speculate about the latest crash. I saw a bit of misconception
being spread here on the internet (imagine that) and wanted to bring back
some reality.
Scott Laughlin
N5SL, Wahoo, Nebraska
Getting Close
www.cooknwithgas.com
_________________________________________________________________
More photos, more messages, more storageget 2GB with Windows Live Hotmail.
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Wing sweep and recent crashes |
Yeah Gary!!! That totally answered my questions. Even though I have
already build a HD your last comment totally straightened me out, wow so
simple.
David Mikesell
23597 N. Hwy 99
Acampo, CA 95220
209-224-4485
skyguynca@skyguynca.com
www.skyguynca.com
----- Original Message -----
From: Southern Reflections
To: zenith-list@matronics.com
Sent: Saturday, May 12, 2007 8:38 PM
Subject: Re: Zenith-List: Wing sweep and recent crashes
DON'T HOLD BACK Gary, tell us what you really think...
----- Original Message ----- Joe N101HD 601XL
From: Gary Boothe
To: zenith-list@matronics.com
Sent: Saturday, May 12, 2007 9:47 PM
Subject: Zenith-List: Wing sweep and recent crashes
MAN! With all your theorizing, conjecturing and armchair
quarterbacking, you guys can take a half story and twist it 9 ways from
Sunday! Without knowing anything but a small portion of the facts you
are willing to question the basics of the CH designs!
What I think is really happening, is that some 'educated' people are
using this list to expound their knowledge and education. If you don't
like the 601XL design.DON'T BUILD IT!!
As for me, I put my $$$ on Mr. Heintz. I'm not building an XL, but I
happen to think the airplane is designed as is for a reason.a reason I
don't understand, because, if I did, I would design and build my own!
Here's a thought: If you don't understand why the wing is swept
forward, maybe Chris Heintz knows more than you.
Don't bother telling me that an 'intelligent' builder should
question everything. Am I willing to just blindly follow? Uh, yeah (see
above).
My vote is that this is a useless thread that will do little or
nothing to help anyone.
Gary Boothe
Cool, CA
601 HDSTD, WW Conversion 90% done,
Tail done, wings done, working on c-section
href="http://www.matronics.com/Navigator?Zenith-List">http://www.matron
href="http://forums.matronics.com">http://forums.matronics.com
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Fuel system contamination |
It nearly sounds like the guy tried to use the same can for his plane
and a 2-cycle lawn mower. Aside from that, perhaps he put
an additive in thinking it would mix and stabilize his fuel over
winter. If he used a bad float, it may have gone south too. I'd at the
least
get a flashlight and a mirror in the tank after emptying it and have a
good look inside.
Larry McFarland at www.macsmachine.com
do not archive
robert stone wrote:
> Members,
> I have not had my ZodiacXL for very long and was unaware of the
> center fuel drain until a friend pointed it out to me. When I opened
> the valve nothing but black materiel came out eventually turning green
> then finally blue. I have no idea what this materiel was but I
> suspect auto fuel. I did not build this aircraft but got it from a
> man in Ringwood, Oklahoma and I suspect he used auto fuel to fly the
> 40 hours off. Have any of you Zodiac601XL builders had an experence
> like this and what action did you take.
>
> Tracy Stone DO NOT ARCHIVE
> Zodiac601XL
> Harker Heights, Tx
> *==========================
>
> *
Message 12
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Recent crashes |
David and other interested folks,
After reading the latest flurry of Emails on the 601 wing structural
failures, I will attempt to clarify what I was hypothesizing about wing
flutter. It is my understanding that flutter problems most frequently
involve control surfaces, for which designers have methods to reduce the
probability of its occurrence. It is also my understanding that there
are problems that occasionally occur involving divergent structural
vibrations (flutter) that cannot be predicted even by the best
designers, of which Chris Heintz is certainly one (I have the greatest
respect and admiration for Chris).
I recall many years ago the difficulties the turboprop Lockheed Electra
had with a string of wing failures traced to a type of torsional flutter
introduced by the engines. The Electra wing was extremely strong and
withstood every load test that the engineers could throw at it, and it
took months, if not years, of work by 100's of the best engineers
Lockheed had to finally pinpoint the problem. The point to be made is
that structural strength alone cannot save a wing if it can be induced
to flutter in a divergent (unstable) fashion. Even the strongest wing
(or any other structure) can be failed if it has a mode of vibration
that is unstable (has a vibration for which the amplitude is increasing
with time). Another classic example is the "Galloping Gertie" suspension
bridge failure that I am sure everyone has seen in the famous
documentary film.
The hypothesis is (and it is just that; a long shot, out-of-the-box
possibility) that the 601XL wing has a torsional stiffness (resistance
to twist) that would normally be sufficient for a safe design; however,
due to some combination of structural and aerodynamic characteristics,
it is insufficiently stiff to damp a particular type of torsional
flutter. This characteristic would not necessarily have any relationship
to the wing's strength as normally measured by load tests or design
calculations. A further feature of this hypothesis is that the center of
lift of the outer sections of the wing produces a twisting force moment
that tends to increase with the angle of twist (angle of attack). The
process would be initiated by some abrupt maneuver, wind shear, or
whatever, that produces some greater than typical twist in the outer
section of the wing, which in turn, introduces more twist due to the
local increased angle of attack. The whole process would depend on a
natural torsional frequency of vibration of the wing that is "in tune"
with an oscillating aerodynamic load that tends to produce progressively
more twist with each oscillation of the vibration. This process, if it
were to occur, would progress very quickly (a matter of a second or
two), until finally the structural strength of the wing skin and rivets
would be exceeded. Using some educated guessing, I would suspect that
the primary mode of failure would be the wing skin rivets where they
attach to the ribs and spar (by hole elongation and rivet shear). As
this mode of failure progresses, the spars would be twisted beyond the
yield point (leaving a twisted spar) and the failure would cascade on
down to the fuselage attach points.
All of this is probably, as someone suggested, overdone hysterics; but I
can't shake the two very strange incidents that were reported here with
regard to the observed wing flutter immediately prior to the wings
"folding back" in the one crash, and the observations of a pilot who
experienced the severe wing vibration over the powerplant cooling
towers. Maybe these two reports are not based in fact, but I took them
to be reliable accounts.
Bob Eli
----- Original Message -----
From: David Downey
To: zenith-list@matronics.com
Sent: Saturday, May 12, 2007 9:38 AM
Subject: Re: Zenith-List: Recent crashes
Bob; You are thinking alongside me. The problem as I see it is that CH
is extraordinarily qualified to have performed this design - if indeed
HE did the complete design. When you look at the almost haphazard way
that the tailwheel modifications are superimposed on the basic design,
there is some indication that he did not do the whole thing.
Another thing that bothers me a little is that the skin bearing/rivet
shear/head pop balance may have been terrific for the 1604 rivet with
the upset factory head when used with 0.016" thick skins but what
happens when you increase the gauge of the skins to 0.020" or 0.025" as
appears to have happened several places...
"Robert N. Eli" <robert.eli@comcast.net> wrote:
David,
I have been reading the discussions on the wing failure topic for
some time (without comment, until now). I believe you are on to
something that I have also been thinking about. One of the crashes was
associated with a ground observation of a severe wing flutter-like
phenomena an instant before the wing was observed to fold upwards.
Another 601 pilot reported a sudden severe vibration of the wings when
over flying a powerplant cooling tower, which he believed was so serious
that he felt lucky to have not sustained a structural failure. I
believe that the structural divergence phenomena is something that needs
to be investigated immediately to see if the 601 wing does in fact have
this behavior. If it does, it would be a common thread that could
explain all the failures. I don't believe for a minute that all of these
failures can be blamed on pilot or builder errors. It seems entirely
plausible to me (as another aerospace engineer) that a wing having the
structural characteristics you describe could be made to produce a
divergent torsional oscillation that would lead to destruction in less
than a second or two under the right conditions. Any sudden maneuver,
that produces enough initial twist, under the right conditions, could
initiate the divergent oscillation that would be almost impossible to
predict, or to correct once it starts.
Bob Eli
----- Original Message -----
From: David Downey
To: zenith-list@matronics.com
Sent: Saturday, May 12, 2007 8:09 AM
Subject: RE: Zenith-List: Recent crashes
Kevin, sometyhing that has bothered me since I decided to build
the XL is the "slight" forward sweep of the wings. As stated before this
is a consequence of the canted spardesign coupled with dihedral effect.
The problem (perhaps I should say the question) in my mind is
this.
There is a phenomenon called structural divergence - or something
like that. Simply put, it is easy to design structure for a multi beam
cantilever panel like a common straight wing that will twist during
uniform loading to either maintian tip angle of attack or reduce the tip
angle of attack. This results in the wing "auto-unloading"
aerodynamically as it bends; the forces generating the bending are
reduced by twisting the nose of the wing down as the panel flexes up and
up as the panlel flexes down. In the case of a forward swept wing this
phenomenon is reversed with conventional metal structure and it as the
panel flexes upward the tip twists to a greater angle of attack
increasing the bending load,increasing the increase in angle of attack,
increasing the bending load.....
With the exception of the german WWII research planes and a german
corporate jet in the 60s, forward swept wings have never been feasible
until carbon composites came along - and the only reason that they made
it possible without massive structure is that you can orient the fibers
to result in bending/twist modes that are opposite the normal.
In the case of a structurally divergent design, onset to failure
can be virtually instantaneous - especialy if prior damage has been
accumulated unseen.
I have to admit, after a 30+ year career in Aerospace Materials
Engineering at the biggest manufacturer, the series of catastrophic
failures for what appear to be stupid triggers worries me some.
I think when I get my plane done and have it licensed I will add
equip or ballast to ensure tat I only operate in the forward half of the
CG range. I keep reading that the XL has very powerful and sensitive
elevator control - staying nose heavy will help me avoid PIOs and other
upset/onset related issues to some degree. And, other than stalling
faster and having to land a little faster due to the reduced
stab/elevator authority, I see no issue with that plan. Anyone disagree?
Thanks.
kevinbonds <kevinbonds@comcast.net> wrote:
I read CH's letter after the Cali crash. He states that hundreds
of these
designs have been flying--some for more than 20 years. This is
true to an
extent. I have the utmost respect for him, but my concern is
with the XL
which I do not think has been around that long, and I'm not sure
how many
examples of it are flying. The success of his designs, certainly
speaks well
of his skills as a designer but doesn't guarantee that some
gremlin can't
exist in one of his newest designs.
Look, I'm not trying to find fault, I'm just trying to be
diligent and
consider the worst case scenario in my planning. So worst case
scenario;
there is a design flaw or a fault in a published number. How do
we rule out
that possibility? In the event we can't, what changes do we
make?
Does the UL in the UK have flaps? Have there been any cases of
damaged wings
during abrupt maneuvers that didn't come off? How abrupt were
those
maneuvers? Or is it like coming to the edge of a cliff there is
either no
damage or rapid, irreversible advance toward the catastrophic.
Can we do
something to at least slow it down long enough so that someone
might live to
tell about it?
------------------------------------------------------------------------
Take the Internet to Go: Yahoo!Go puts the Internet in your
pocket: mail, news, photos & more.
href="http://www.matronics.com/Navigator?Zenith-List">http://www.matron
href="http://forums.matronics.com">http://forums.matronics.com It's
here! Your new message!Get
new email alerts with the free Yahoo! Toolbar.
Message 13
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | New letter from Chris Heintz!! 5/11 |
For those of you with access to the builders pages, there is a new letter from
Chris addressing the recent crashes. As a recap, he is still confident in the
design the testing that has been done but he is doing the testing again to confirm.
He also has some interesting note to those now flying.
Here is the link: http://www.zenithair.com/news/c-heintz-5-10-2007.html
--------
601 XL kit
Tail, control surfaces and 1 wing complete
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112583#112583
Message 14
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Cabin Floor and Rudder Pedals |
Thanks listers - a couple people have made this bright suggestion. Can
someone point me in the direction of where I can get the bearing material?
(If you missed the earlier email we are talking about the rudder pedal
bearings.)
Thanks, Michael
On 5/13/07, Craig Payne <craig@craigandjean.com> wrote:
>
> I may not be clear on what the problem is but would making a custom
> bearing remove the need to replace any metal?
>
> -- Craig
>
Message 15
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Folks,
Any recommendations for moving the 601 around to / from its hangar? I
would guess a tow/push bar for the nose wheel would work, but haven't
found one yet. I normally pull / push at the prop hub. Any ideas for
an inexpensive, easy way to do this or make one would be appreciated.
Thanks.
Message 16
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | misinformation about HD/HDS landing gear |
I've always assumed the tilt in the spar was an artifact left over from
the 601
HD wing, which had the landing gear mounted to the spar. This gave the
landing
gear the tilt that put the wheels behind the center of rotation, just as
the
tilted firewall puts the front wheel forward of the firewall. I think
all
601 wings have had the tilted main spar, thus slightly forward sweep to
the wing.
Not so. The landing gear in the HD/HDS series is contained in gear
boxes built into the two outer ribs (.032, heaviest in the wing) of the
center section, and far behind the spar. If they were attached to the
spar, boarding the a/c (unless it were a taildragger) would be an
exciting event. And if you got in think of the squirrelly rotation!
The spar is vertical (slight variations due to incidence).
To check this stuff you just have to go to the Zenith site and scan a
few diagrams - I know, it's just easier to spout off "facts" instead of
checking them, but then this list has degenerated into chaos the last
year or so. I loved the plea to "...GET BACK TO BUILDING"! Heck, this
list hasn't been anything but opinions and drivel for a long time, how
can you build if you're typing all the time?
do not archive
CAVU jeff
Message 17
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | turnbuckles and safety wire |
AC 43 is a great book. Also available is a wealth of quick info in the
Aircraft Spruce catalogue - which is like to be in the workshop of more
builders than the government document.
Page 142 has a quick tutorial on the subject.
Why not use MS21256 clips (same page), I know they are a heck of a lot
easier to work with once the project is together and you need an
adjustment. K.I.S.S.
CAVU
jeff
Message 18
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Fuel system contamination |
Hi Tracy,
Many kit built XLs use black rubber hose for fuel line. I have heard
many reports that this tends to turn the fuel funny colors until the
hose is completely cleaned out.
This is relatively common. I wouldn't scrap the plane yet for this reason.
Happy landings,
Paul
XL fuselage
do not archive
At 06:26 AM 5/13/2007, you wrote:
>Members,
> I have not had my ZodiacXL for very long and was unaware of
> the center fuel drain until a friend pointed it out to me. When I
> opened the valve nothing but black materiel came out eventually
> turning green then finally blue. I have no idea what this materiel
> was but I suspect auto fuel. I did not build this aircraft but got
> it from a man in Ringwood, Oklahoma and I suspect he used auto fuel
> to fly the 40 hours off. Have any of you Zodiac601XL builders had
> an experence like this and what action did you take.
>
>Tracy Stone DO NOT ARCHIVE
>Zodiac601XL
>Harker Heights, Tx
>
Message 19
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Mark,
As an instrument instructor I can easily buy the loss of control leading to the
overstress of the airplane idea. It happens, and not just to XL's.
I see that CH has announced that he is going to do some additional structural testing,
and I look forward to that as well. The one problem I have with laying
sandbags on a wing is that I don't think they truly simulate the conditions
found in flight, and the reports of possible wing flutter are disturbing. I
am not an aeronautical engineer so all I can do is proceed forward with faith
while those with more knowledge of the subject try to figure it out.
I do have one question however..... In the Feb 06 crash there was some early info
concerning missing or improper rear spar attachment bolts. The NTSB does not
really address that scenario in it's conclusions. Do you have any more information
you can add?
Still building!
Tim
--------
DO NOT ARCHIVE
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Working on wings
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112598#112598
Message 20
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | New letter from Chris Heintz!! 5/11 |
Wow. CH is a good dude. I'm glad that the factory is being so proactive
about this. This is responsible business practice and the sign of a smart
designer. In our litigious society one is not accustomed to such public
statements after an accident.
Kevin Bonds
Nashville TN
601XL Plans building.
http://home.comcast.net/~kevinbonds
do not archive DO NOT ARCHIVE
-----Original Message-----
From: owner-zenith-list-server@matronics.com
[mailto:owner-zenith-list-server@matronics.com] On Behalf Of swater6
Sent: Sunday, May 13, 2007 9:30 AM
Subject: Zenith-List: New letter from Chris Heintz!! 5/11
For those of you with access to the builders pages, there is a new letter
from Chris addressing the recent crashes. As a recap, he is still confident
in the design the testing that has been done but he is doing the testing
again to confirm.
He also has some interesting note to those now flying.
Here is the link: http://www.zenithair.com/news/c-heintz-5-10-2007.html
--------
601 XL kit
Tail, control surfaces and 1 wing complete
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112583#112583
Message 21
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Fuel system contamination |
I built a 701 and had the same problem with fuel color and tiny bits of material
coming through. I washed the tanks very well with soap and water, and rinsed
several times before installing them. I blew the fuel lines out with high pressure
air before installation. After installation I ran at least five gallons
of gas through each tank several times all the way to the carbs. untill the debris
was (nearly) gone, I was sure everything was as clean as one could get the
fuel components yet the fuel continued to come through colored and very small
various colored particles after sitting a while. I am convinced it was all coming
from the black rubber fuel lines. After seventy five hours, all seems clear.
All the fuel I add is filtered while being poured into the tanks. Nothing
ever comes out of my fuel draines (four) any more.
--------
Ron Lee
Tucson, Arizona
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112604#112604
Message 22
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: New letter from Chris Heintz!! 5/11 |
Thank you Scott.
That letter tells me that Chris is once again looking for bugs in the
XL design. That is the best news I could have hoped for. I believe
if there is a problem in the design he will find it.
Paul
XL fuselage
At 07:30 AM 5/13/2007, you wrote:
>
>For those of you with access to the builders pages, there is a new
>letter from Chris addressing the recent crashes. As a recap, he is
>still confident in the design the testing that has been done but he
>is doing the testing again to confirm.
>He also has some interesting note to those now flying.
>
>Here is the link: http://www.zenithair.com/news/c-heintz-5-10-2007.html
>
>--------
>601 XL kit
>Tail, control surfaces and 1 wing complete
Message 23
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Tim-
Check larry@macsmachine.com
Bill Naumuk
HDS Fuse/Corvair
Townville, Pa
----- Original Message -----
From: "Timothy Croy" <twcroy@gmail.com>
Sent: Sunday, May 13, 2007 10:51 AM
Subject: Zenith-List: Tow Bar
>
> Folks,
>
> Any recommendations for moving the 601 around to / from its hangar? I
> would guess a tow/push bar for the nose wheel would work, but haven't
> found one yet. I normally pull / push at the prop hub. Any ideas for
> an inexpensive, easy way to do this or make one would be appreciated.
>
> Thanks.
>
>
>
>
Message 24
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Tim,
I've got a page that describes tow bar and the travel stop for the 601.
I've built a dozen or so
and have drawings on the page that show how to make one. The tow bar can
fit on the shelf and you take it
with you for ground handling at any airport. Both are very light.
http://www.macsmachine.com/images/Itemsforsale/full/travel-stop-and-stear-link.gif
http://www.macsmachine.com/images/Itemsforsale/full/tow-bar-construct.gif
Enough info that you can make one or order them both for $100.00 total.
Larry McFarland
Timothy Croy wrote:
>
> Folks,
>
> Any recommendations for moving the 601 around to / from its hangar? I
> would guess a tow/push bar for the nose wheel would work, but haven't
> found one yet. I normally pull / push at the prop hub. Any ideas for
> an inexpensive, easy way to do this or make one would be appreciated.
>
> Thanks.
>
Message 25
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | turnbuckles and safety wire |
> Page 142 has a quick tutorial on the subject.
Here is the page:
http://www.aircraftspruce.com/pdf/2007Individual/Cat07142.pdf
-- Craig
Message 26
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
As a totally new member to this group ( builder's of Chris'
designs). I have found the discussion leading up to this point to
be very thoughtful, useful and educational. The letter from Chris
shows he is taking a responsible, professional approach. I am
looking forward to his results.
Jerry Hey STOL 701
Message 27
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Scott made the actual tow bar from a crutch:
http://www.cooknwithgas.com/Towbar.html
The big determination on how you attach the bar is if you have wheel pants
or not.
-- Craig
Message 28
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Recent crashes |
I was going to add this yesterday, swept forward is more a dynamic test than a
static test. All the sandbags in the world won't tell you about the dynamic characteristics
of a wing.
I just stopped at a small airport to take a look at a few production planes. The
Grumman Traveller appears to have an ever so slightly forward swept wing as
well. It also has ribs spaced every 15 inches, not 21 or 22 inches. Personally,
I feel adding a ribs between 4 and 5, 5 and 6, 6 and 7, 7 and 8, and 8 and 9
on the XL would be highly advisable. I was going to put flase ribs (L angle)
in between these ribs anyway because for some oil-canning I'm getting on the lower
skin. Oil canning would be a great place for the wing to start to fail. The
slightly swept forward wing may not be a problem, as long as the wing structure
is beefy enough and has enough attach points. 21+ inch spacing for the center
ribs is is probably pushing it.
[quote="MaxNr(at)aol.com"]I am uncertain if the swept forward 601XL wing lends
it self to load testing with sand bags. How do you duplicate that twisting feature?
I would like to see what if any load testing that ZAC has done. I posted
some pictures of testing done on a relatively rare airframe after the builder
decided to "kit" this plane. No. He never rebuilt it and put it back in the air
as some suggest. Testing to failure was a responsible course to take when he
offered it to the public. Has ZAC done this?
A friend told me that when he was a Beechcraft test pilot in the early 60's, witnessed
a load test on a Beech 23 Musketeer. The wing and fuselage were supported
four feet above the floor. A great deal of weight was applied until the belly
touched the floor. For about an hour. The weight was removed, belly came
up and a straight edge used on the wing. Zero deformation. Nothing cracked. Although
the 23 was not his project, (his was the big engine, armed T-34) he did
ride with the project pilot through some wild aerobatics and observed the wing
tips flex several feet under high G. Several feet. He was a WW2 fighter pilot
that flew every US, Brit, German & Italian fighter that he could. The Be 23
has a laminar flow airfoil that looks somewhat like the 601XL. The skin forward
of the spar is bonded with no rivets. I've never heard of a structural failure.
I've been doing loops since puberty and would like to do one on my birthday. (70th)
The last thing I want to have to do is add Piper Pawnee lift struts or Fly-Baby
flying wires. My wife has restricted me to no more than 2 G because of
my age. One G when she is aboard.
Do not archive
Bob Dingley
Pace, FL
XL
**************************************
See what's free at http://www.aol.com.
> [b]
--------
Andy Shontz
CH601XL - Corvair
www.mykitlog.com/ashontz
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112610#112610
Message 29
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Recent crashes |
I think it's definitely worth looking into.
[quote="robert.eli(at)comcast.net"]David and other interested folks,
After reading the latest flurry of Emails on the 601 wing structural failures,
I will attempt to clarify what I was hypothesizing about wing flutter. It is
my understanding that flutter problems most frequently involve control surfaces,
for which designers have methods to reduce the probability of its occurrence.
It is also my understanding that there are problems that occasionally
occur involving divergent structural vibrations (flutter) that cannot be predicted
even by the best designers, of which Chris Heintz is certainly one (I have
the greatest respect and admiration for Chris).
I recall many years ago the difficulties the turboprop Lockheed Electra had with
a string of wing failures traced to a type of torsional flutter introduced
by the engines. The Electra wing was extremely strong and withstood every load
test that the engineers could throw at it, and it took months, if not years,
of work by 100's of the best engineers Lockheed had to finally pinpoint the
problem. The point to be made is that structural strength alone cannot save
a wing if it can be induced to flutter in a divergent (unstable) fashion.
Even the strongest wing (or any other structure) can be failed if it has a mode
of vibration that is unstable (has a vibration for which the amplitude is
increasing with time). Another classic example is the "Galloping Gertie" suspension
bridge failure that I am sure everyone has seen in the famous documentary
film.
The hypothesis is (and it is just that; a long shot, out-of-the-box possibility)
that the 601XL wing has a torsional stiffness (resistance to twist) that
would normally be sufficient for a safe design; however, due to some combination
of structural and aerodynamic characteristics, it is insufficiently stiff
to damp a particular type of torsional flutter. This characteristic would not
necessarily have any relationship to the wing's strength as normally measured
by load tests or design calculations. A further feature of this hypothesis
is that the center of lift of the outer sections of the wing produces a twisting
force moment that tends to increase with the angle of twist (angle of attack).
The process would be initiated by some abrupt maneuver, wind shear, or
whatever, that produces some greater than typical twist in the outer section
of the wing, which in turn, introduces more twist due to the local increased
angle of attack. The whole process would depend on a natural torsional frequency
of vibration of the wing that is "in tune" with an oscillating aerodynamic
load that tends to produce progressively more twist with each oscillation
of the vibration. This process, if it were to occur, would progress very quickly
(a matter of a second or two), until finally the structural strength of
the wing skin and rivets would be exceeded. Using some educated guessing, I would
suspect that the primary mode of failure would be the wing skin rivets where
they attach to the ribs and spar (by hole elongation and rivet shear). As
this mode of failure progresses, the spars would be twisted beyond the yield
point (leaving a twisted spar) and the failure would cascade on down to the
fuselage attach points.
All of this is probably, as someone suggested, overdone hysterics; but I can't
shake the two very strange incidents that were reported here with regard to
the observed wing flutter immediately prior to the wings "folding back" in the
one crash, and the observations of a pilot who experienced the severe wing
vibration over the powerplant cooling towers. Maybe these two reports are not
based in fact, but I took them to be reliable accounts.
Bob Eli
> ---
--------
Andy Shontz
CH601XL - Corvair
www.mykitlog.com/ashontz
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112613#112613
Message 30
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Cabin Floor and Rudder Pedals |
The plans list the material as "Nylon66" (on page 6B9). Spruce sells "Nylon"
but I wouldn't assume it is the same (superficially green vs. white):
http://www.aircraftspruce.com/catalog/mepages/nylon.php
The scratch builders should be able to say where they obtained theirs.
Here are the physical properties of "66":
http://www.3d-cam.com/materials/nylon_66_6.asp
This page seems to indicate sub-types within 66:
http://www.ashleypoly.com/nylon_guide.htm
So the safest and simplest source is Zenith. You can order most parts
"undrilled" but you may have to specifically request a block of the raw
material. Given the sequence of events I bet you could persuade them to give
it to you free. But I think you should find a machinist to actually make
your custom block.
Do you have any pictures of the problem?
-- Craig
Message 31
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 601XL crash in Modesto CA last year |
I just have to put my two cents in here. That's not a very well writte
n report. If the NTSB wants to give me something to work with, how ab
out stating that the rear spar remains attached to the carry-through b
y means of x AN-x bolts,, and the carry-through remains attached to th
e fuselage by means of x rivets. If the wing came off, tell me that th
e rear spar showed evidence of the AN-x bolt having torn through the s
par at xx angle. If the wing failed, how about telling me the wing spa
r fractured (or ribs separated, or whatever,) at xxx station. Then I c
ould extrapolate that to my own wing, and perhaps avoid the same fate.
Any investigative report should be written under the Martian Rule: Y
ou are telling a Martian, who just got here and has no knowledge of AN
YTHING earthly, except the ability to read, what happened.=0A=0A
Paul Rodriguez=0A601XL/Corvair=0ADO NOT ARCHIVE=0A ----- Ori
ginal Message ----- =0A From: Mark Sherman<mailto:msherman95632@ya
hoo.com> =0A To: zenith-list@matronics.com<mailto:zenith-list@matr
onics.com> =0A Sent: Friday, May 11, 2007 5:14 PM=0A Subject:
Re: Zenith-List: Re: 601XL crash in Modesto CA last year=0A=0A
@yahoo.com<mailto:msherman95632@yahoo.com>>=0A=0A Chris.=0A
=0A How could the bolts be missing and the wing aft attach pont re
main secured to the fuselage. This is refering to the wing attach poin
t not the fuselage attach point.=0A=0A Mark S.=0A do not ar
chive=0A=0A ----- Original Message ----=0A From: chris Sinf
ield <chris_sinfield@yahoo.com.au<mailto:chris_sinfield@yahoo.com.au>>
=0A To: zenith-list@matronics.com<mailto:zenith-list@matronics.com
>=0A Sent: Friday, May 11, 2007 2:44:04 PM=0A Subject: Zenith-
List: Re: 601XL crash in Modesto CA last year=0A=0A=0A --> Z
enith-List message posted by: "chris Sinfield" <chris_sinfield@yahoo.c
om.au<mailto:chris_sinfield@yahoo.com.au>>=0A=0A You can read i
t 2 ways..=0A I read it as the bolts were there on the main spar b
ut not on the aft attachment point. as it just said the attachment po
int remained attached to the fuse.. very different wording to the main
spar paragraph.. Also this aircraft was NOT in any turbulance but in
the circut area.. =0A Chris=0A=0A=0A=0A=0A Read t
his topic online here:=0A=0A http://forums.matronics.com/viewto
pic.php?p=112311#112311<http://forums.matronics.com/viewtopic.php?p
=112311#112311>=0A=0A=0A=0A=0A=0A=0A=0A
=0A=0A =0A http://answers.yahoo.com/dir/?link=list&si
d=396545469<http://answers.yahoo.com/dir/?link=list&sid=39654546
=======================
=======================
=======================
=======================
=======================
=====0A=0A=0A=0A
Message 32
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Actually, there is a practical way to end the controversy, but it woul
d be expensive......and somewhat dangerous. Equip an XL with a BRS ch
ute, and the pilot, an experienced skydiver, with a personal chute. In
stall a recording G-meter. Take the plane up to safe altitude, and str
ess it to destruction. Only empirical evidence will prove the point. B
ut is it really feasible? Personally, I would rather fly with devout
cowardice.=0A=0APaul Rodriguez=0ADO NOT ARCHIVE=0A -----
Original Message ----- =0A From: Paul Mulwitz<mailto:p.mulwitz@wor
ldnet.att.net> =0A To: zenith-list@matronics.com<mailto:zenith-lis
t@matronics.com> =0A Sent: Friday, May 11, 2007 5:49 PM=0A Sub
ject: Re: Zenith-List: accident=0A=0A=0A --> Zenith-List mes
sage posted by: Paul Mulwitz <p.mulwitz@worldnet.att.net<mailto:p.mulw
itz@worldnet.att.net>>=0A=0A Hi Tom,=0A=0A In general, I
agree with you on this point. If people are indeed =0A exceeding
the limits of these airplanes then failures are the =0A expected
result.=0A=0A Unfortunately, we don't know if the design limits
were exceeded or =0A not. What we do know is that a lot of plane
s are disintegrating in =0A flight. Furthermore, they all seem to
be Zodiac XLs. I haven't =0A heard any reports of similar failur
es in any other model of =0A LSA. Maybe they have been occurring
and I just haven't heard about =0A them. That is part of the reas
on I wrote to the experts at EAA to =0A ask if these accidents see
m to be out of the ordinary. They haven't =0A responded to me yet
=0A=0A This situation reminds me of a similar experience with
V-tail =0A Bonanzas. Those planes had a long history of in-flight
structural =0A failures. For decades, Beechcraft and others said
it was simply a =0A case of poor pilots exceeding the Vne of the
plane and pulling up too =0A hard causing the tail to fall off. T
he pilots in question couldn't =0A defend their skills since they
were all dead. Then after decades of =0A this same failure occurr
ing again and again they came out with a =0A design change reinfor
cing the tail section of these planes. After =0A that the break-u
ps came to an abrupt end. To my knowledge there has =0A not been
another one since.=0A=0A I don't know how to proceed with this
whole situation. I know I am =0A alarmed and facing flight testin
g of my XL which will probably be =0A completed within a few month
s. I don't want to bring any lawyers =0A into this or have any la
wsuits. I just want to know if there is a =0A design flaw and how
it can be fixed if there is one.=0A=0A I don't like all the sp
eculation. I don't like people thinking there =0A is a fatal desi
gn flaw in my airplane. Similarly, I don't like all =0A the accid
ent reports and I really don't like speculation that it is =0A all
the fault of the dead pilots. I wish there was a practical way
=0A to find out the real truth of this matter.=0A=0A Paul
=0A XL fuselage=0A=0A=0A=0A=0A=0A=0A At 02:09 P
M 5/11/2007, you wrote:=0A > Guys, if you re-read all the accid
ent reports, you'll find that =0A > it appears the aircraft operat
ing limitations were exceeded in =0A > nearly every case (speculat
ion yes, but based on preliminary =0A > reports). I hate to break
it to you, but if you yank back on a =0A > fully loaded C150, som
ething's going to break.=0A > This discussion is starting to s
ound a lot like the US media =0A > treats any shocking incident.
If a kid shoots up a classroom, it's =0A > the gunmakers fault. S
mokers are dying like flies, and it's the =0A > cigarrette compani
es fault. I don't really like guns or =0A > cigarrettes myself, b
ut it's the idiot on the other end of them =0A > that is to blame
for any problems they create. When did we stop =0A > thinking for
ourselves in this country?=0A > If an aircraft comes down bec
ause the pilot did something the =0A > designer said not to do (pu
ll high G's at high gross weight), it's =0A > the pilot's fault an
d problem. The poor aircraft company shouldn't =0A > even be brou
ght into it. (See discussions earlier this week =0A > regarding f
=======================
=======================
//www.matronics.com/Navigator?Zenith-List<http://www.matronics.com/Nav
=======================
=======================
= Same great content now also available via the Web Forums!=0A _
-= --> http://forums.matronics.com<http://forums.matronics.com/>
=======================
==================0A=0A=0A
=0A
Message 33
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Cabin Floor and Rudder Pedals |
www.mcmaster.com
www.usplastics.com
Craig Payne <craig@craigandjean.com> wrote: The plans list the material as
"Nylon66" (on page 6B9). Spruce sells "Nylon" but I wouldn't assume it is the
same (superficially green vs. white):
http://www.aircraftspruce.com/catalog/mepages/nylon.php
The scratch builders should be able to say where they obtained theirs.
Here are the physical properties of "66":
http://www.3d-cam.com/materials/nylon_66_6.asp
This page seems to indicate sub-types within 66:
http://www.ashleypoly.com/nylon_guide.htm
So the safest and simplest source is Zenith. You can order most parts "undrilled"
but you may have to specifically request a block of the raw material. Given
the sequence of events I bet you could persuade them to give it to you free.
But I think you should find a machinist to actually make your custom block.
Do you have any pictures of the problem?
-- Craig
Dave Downey
Harleysville (SE) PA
Zodiac 601XL/Corvair?
---------------------------------
Sick sense of humor? Visit Yahoo! TV's Comedy with an Edge to see what's on, when.
Message 34
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Rolled bead for fuel tank |
Hello All,
The drawings for the XL specify rolled bead for both
the top rear side and also on both ends. How are these
made and what tools are needed to do this?
On www.ch601.org two tools are described. A complex one
that requires a lathe and welding to build and a version
based on form blocks with a round metal form in it. Does
anyone have experience using the form block based tool
to make the relief beads?
Regards,
Maarten
601XL scratch building wings.
Message 35
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Rolled bead for fuel tank |
Maarten, Thanks for the reference. I am going to try the simpler
beading method too now that you have pointed it out. Have you
experimented yet with welding the tank flange. That is something I
am going to practice this week. I have plenty of experience TIG
welding but never on such thin material. My first attempt (on
scrap), will be with .040 tungsten and .040 4043 mig wire for
filler. I plan to start with about 20 amps and adjust from there. I
have heard that some have substituted .032 for .025 but I would like
to use the lighter material if I can. Do you (or anyone) have any
words of wisdom? Thanks, Jerry
On May 13, 2007, at 4:20 PM, Maarten Versteeg wrote:
> <maarten.versteeg@swri.org>
>
> Hello All,
>
> The drawings for the XL specify rolled bead for both
> the top rear side and also on both ends. How are these
> made and what tools are needed to do this?
> On www.ch601.org two tools are described. A complex one
> that requires a lathe and welding to build and a version
> based on form blocks with a round metal form in it. Does
> anyone have experience using the form block based tool
> to make the relief beads?
>
> Regards,
> Maarten
>
> 601XL scratch building wings.
>
>
Jerry Hey STOL 701
Message 36
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
I ran into a problem fitting the front wing struts and found that others
have had the same problem when I searched the archives, but I didn't
find much in the way of solutions. The angle of the welded U plate is
off by about 6 or 8 degrees from the orientation of the wing pick-up and
the gear strut for a proper fit. The plans show the U fittings as
parallel to each other, which mine are (more or less), but I notice that
some have said the Czech Aircraft front strut has the U welded 6 degrees
from one another which seems about right.
Any thoughts or solutions would be greatly appreciated.
Gordon
Message 37
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Hello All,
Ocasionally poster, early in the process 601XL builder here. I would like some
advice as I try to move forward and finish the tail section kit.
After weeks(!) of checking and rechecking alignment, I finally jumped in and drilled
the holes for the top skin to skeleton on the stab. Since this was a kit,
the skin pilot holes were already drilled. So far so good.
Next I try to position and align the end ribs - everything looks good - leading
snug with the end of the rib - and so I drill through the skin holes again. This
is the kit skin with pre-drilled holes and the kit end rib - no problem ,
right? Wrong! One of the holes goes right into the crimped area of the rib.
I look at the drawings and they show 13 holes, the actual rib and skin have 12
holes!
Has anyone else had this experience? Can I get by with a rivet in the side (not
all the way at the bottom) of one of the crimped areas on the end rib flange?
Do not archive
Ron
San Diego 601XL
----------------------------------------------------------------------
Find out how you can get spam free email.
http://www.bluebottle.com
Message 38
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Rolled bead for fuel tank |
Harbor Freight sell a beading tool. I have no experience with it, but I think other
guys on this list have used it.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93364
Dave Clay
Temple, TX
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112630#112630
Message 39
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: NTSB search for breakup accidents. |
I think the real telling piece would be to some how find out which of the XL's
were scratch built. The spar design looks very solid but material selection and
preparation play a major part in the integrity of the finished product.
--------
Ron Lendon, Clinton Township, MI
Corvair Zodiac XL, ScrapBuilder ;-)
http://www.mykitlog.com/rlendon
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112632#112632
Message 40
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Fuel system contamination |
Paul,
No kit producer would include rubber hoses in his fuel system
because and petroleum products of any kind will melt rubber. They use a
hose in the flex line areas called neoprene.
Tracy Stone
----- Original Message -----
From: Paul Mulwitz
To: zenith-list@matronics.com
Sent: Sunday, May 13, 2007 10:46 AM
Subject: Re: Zenith-List: Fuel system contamination
Hi Tracy,
Many kit built XLs use black rubber hose for fuel line. I have heard
many reports that this tends to turn the fuel funny colors until the
hose is completely cleaned out.
This is relatively common. I wouldn't scrap the plane yet for this
reason.
Happy landings,
Paul
XL fuselage
do not archive
At 06:26 AM 5/13/2007, you wrote:
Members,
I have not had my ZodiacXL for very long and was unaware of the
center fuel drain until a friend pointed it out to me. When I opened
the valve nothing but black materiel came out eventually turning green
then finally blue. I have no idea what this materiel was but I suspect
auto fuel. I did not build this aircraft but got it from a man in
Ringwood, Oklahoma and I suspect he used auto fuel to fly the 40 hours
off. Have any of you Zodiac601XL builders had an experence like this
and what action did you take.
Tracy Stone DO NOT ARCHIVE
Zodiac601XL
Harker Heights, Tx
Message 41
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Thanks all for the ideas on the tow bar. I'll probably go with the
crutch rig. Tim
On 5/13/07, Craig Payne <craig@craigandjean.com> wrote:
>
> Scott made the actual tow bar from a crutch:
>
> http://www.cooknwithgas.com/Towbar.html
>
> The big determination on how you attach the bar is if you have wheel pants
> or not.
>
> -- Craig
>
>
Message 42
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Flatten out the crimp in the rib so the rivet will pull tight, and put another
crimp in between the rivet holes. Or maybe the skin is on backwards?
--------
Ron Lendon, Clinton Township, MI
Corvair Zodiac XL, ScrapBuilder ;-)
http://www.mykitlog.com/rlendon
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112640#112640
Message 43
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Rolled bead for fuel tank |
I used the Harbor Freight beading tool and it worked great.
I just posted a blurb about welding my tanks about a week ago.
The filler neck flange goes on the inside of the tank first. The seam welds are
easy if you can see that small of a puddle. I needed 3.25+ reading glasses,
might be an age thing :? Anyway about 27 to 29 amps were used and very little
4043 filler rod was needed. The Miller 200 Syncrowave was used with .062 tungsten,
a pulse of about 2.3 and a balance of 5.0.
Hope that helps.
--------
Ron Lendon, Clinton Township, MI
Corvair Zodiac XL, ScrapBuilder ;-)
http://www.mykitlog.com/rlendon
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112642#112642
Message 44
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Oh Please, I know Chris has spin tested and flutter tested every plane
he has designed. I have included an article at the bottom of this
letter, this article is a re-print from 91. It is just as valid today.
It is long but it outlines everything and the philosophies of Chris and
the business. Please take the time to read it. Chris goes way beyond the
necessary steps in his designs to ensure a safe plane for people to
learn on and enjoy for many years.
I am intrigued that Chris is going to destroy another 601 in a stress
test, he doesn=92t have to in my mind the first test and the math are
well
documented and above industry standards. However, I feel that he is
likely doing it for you folks, All accidents in the last 14 mos I
believe have been explained or can be, unfortunately the FAA isn=92t
going
to be clear in it=92s posted findings. No matter, Chris is going to take
the steps necessary to make everyone feel better.
One thing I=92m sure about, not many companies in this industry will go
that extra step. But that is part of the reasons why you choose a Chris
Heintz design, you know in the end you can trust the man behind the
design.
Mark Townsend
Can-Zac Aviation Ltd.
HYPERLINK
"mailto:president@can-zacaviation.com"president@can-zacaviation.com
HYPERLINK "http://www.can-zacaviation.com/"www.can-zacaviation.com
-----Original Message-----
From: owner-zenith-list-server@matronics.com
[mailto:owner-zenith-list-server@matronics.com] On Behalf Of
paulrod36@msn.com
Sent: Sunday, May 13, 2007 2:33 PM
Subject: Re: Zenith-List: accident
Actually, there is a practical way to end the controversy, but it would
be expensive......and somewhat dangerous Equip an XL with a BRS chute,
and the pilot, an experienced skydiver, with a personal chute. Install a
recording G-meter Take the plane up to safe altitude, and stress it to
destruction. Only empirical evidence will prove the point. But is it
really feasible? Personally, I would rather fly with devout cowardice.
Paul Rodriguez
DO NOT ARCHIVE
ARTICLE REPRINT
Grassroots manufacturing
The evolution of 'homebuilts' into factory-builts - =E0 la Zenair
Zenith Aircraft Company
Stars of Zenair's fleet: The ZODIAC CH 601 and the STOL CH 701
* by Kenneth Armstrong
Reprinted from "AVIATION TODAY"
CANADA'S AVIATION industry - particularly the homebuilt sector - is
fortunate that 18-year-old, French-born HYPERLINK
"http://www.zenithair.com/c-heintz.html"Chris Heintz decided to enter
aeronautical engineering, and that a series of events led him to
emigrate from Switzerland to Canadian shores a decade later.
Heintz's late-Fifties education - at the world-renowned ETH in
Switzerland - was computerless. Says Heintz: Computer-driven
calculations do not allow sufficient leeway for unusual situations, and
most are developed for large, heavy jet transports. Computer predictions
too often are invalidated by prototype performance.
His first job involved flutter analysis for the Aerospatiale Concorde.
At that time, Avions Robin was building the popular all-wood Jodel
series under license. A row with the designers left Mr. Robin looking
for an aeronautical engineer to create a design. He found Heintz, whom
he appointed Chief of Engineering. Chris quickly learned two things: how
to work with people, and how difficult it was to design a whole new
aircraft. In the yearly Race of Sicily, where competitors flew for six
hours at wave-top heights with Lycoming 0-320s turning at 3600 rpm,
Heintz's design won the prize for three consecutive years, and was
disqualified from running again in fairness to other entries.
A decade later, Avions Robin was building an aircraft per day; Chris
took on civic responsibility by accepting the post of town mayor. But he
had to leave the company - the day before it was to become unionized and
staffed essentially by surplus army personnel. But he had signed a
contract with Avions Robin promising not to work as an engineer in
Europe if he left the company.
This stipulation unwittingly engineered his departure from Europe. With
his wife and five children, he pinned a world map with Waldorf school
locations, and chose Brazil, only to discover that its climate was too
hot for serious productivity. Canada was the alternative, and
DeHavilland in Toronto was the employer.
HOMEBUILT ROOTS
Heintz's homebuilt penchant began one day back at Avions Robin in
France, where he started designing his own two-seat, all-metal Zenith
during, his spare time. He finished the airframe in six months and it
was flown two years later. It was an immediate success, and Chris used
the Zenith for commuting to work.
The plane was flown later at the Oshkosh Fly-in, where it sparked
considerable interest. Although hassles with DoT [Canadian Department of
Transportation] were ripe, Heintz was eventually allowed to bring the
Zenith to Canada. Says he: DoT in those days was staffed by British
personnel who had moved to Canada after crushing general aviation in
Great Britain.
After some time with DeHavilland working on the Dash 7, he despaired of
the whole concept of government employment and decided to strike out on
his own to help fill the need for well-designed recreational aircraft.
With his friend Gerry Boudreau in charge of production, and working out
of their double-car garages, Zenair began production. Gerry in Bolton
specialized in welded structures and inventory control, while Chris
fabricated the sheet-metal structures in Richmond Hill. This little
outfit grew, and eventually produced 700 flying aircraft (plus many more
in varying stages of construction or storage).
Heintz's aim in building kitplanes, in his own words, is "to help in the
cure of ills plaguing modem-day society." If one doesn't have a goal to
help others, in time one will become emotionally ill. Most individuals
have a job that's boring to them ' nothing more than a money-motivated
endeavor. When they go home, they want to be involved in something
creative.
"By providing safe, well-designed aircraft," says Heintz, "I can
contribute to the achievements and fulfillment of kitbuilders and pilots
around the world. Many builders claim their project was the best
experience of their life. This, and wives who are gushy about their
mutual accomplishments, are my rewards."
The Experimental Aircraft Association estimates an average completion
rate of 8 - 10% for first-time kit-builders. The Zenair kits are
apparently completed by 98% of the buyers! The most important factor
here is the quality of the kit, says Heintz. Companies often claim their
kits are 49% complete, when in actual fact they could be much less.
Finishing details, reading the plans, and shopping for materials not
provided in the kit, are major time consumers. On the other hand,
professionally written construction manuals with supportive photos can
save builders a great deal of time. A project that gets interrupted due
to lack of materials or information tends to be abandoned.
Builders should therefore look for factory support and quality when it
comes to choosing a homebuilt.
Design criteria are also important, says Heintz: To avoid serious injury
or fatalities during crash landings, the flaps up stall speed must be
below 50 mph. "Many think my central control system between pilots was
created to reduce weight and complexity. In fact, it was to move the
sticks away from a potentially hazardous location. Similarly, throttles
are mounted in upper outboard portions of the instrument panel where
they can't impale pilots."
Since maintaining high proficiency is difficult for sport aviators,
their aircraft must be simple and efficient. Generally, this means
avoiding retractable gear, variable-pitch props and complex high-lift
devices. Zenair's CH 701 STOL wing achieves a lift coefficient of 3.1
with a simple fixed slat! "My visits to major flying shows has taught me
that few people really know what kind of plane is best for them. My
aircraft are designed to be useful to the largest segment of sport
pilots."
"Because I'm six-feet-two, cockpit access and comfort can be less than
ideal. It is important to consider creature comforts, especially for
cross-country flights."
In the case of kit production, the package should be produced so that
all difficult tasks such as welding, and heat treatment are completed by
the factory. The builder should be able to put the aircraft together
with basic hand tools.
There is a trend toward higher prices for amateur-builts. One reason,
says Heintz, is that more of them now are supplied as ready-to-assemble
kits rather than as sets of plans. Also, the quality of desion has been
improving - more aircraft are built to FAR 23 and European JAR
standards, adding further to developmental costs. Professional
engineering will always cost more than the creations of relatively
unqualified designers. Also, many companies do not conduct sufficient
testing of their prototypes before offering kits to the public. Not only
the wings but the tail, engine mounts and landing gear should all be
load-tested. Wings should also have torsional and twisting loads applied
- similarly to those encountered during flight. An aircraft that has not
been flutter-tested or spin-tested should not be released for public
use. This testing all costs money.
Prebuilt kits begin with high-cost tooling. At Zenair, for example, a
CNC computer-controlled drilling machine produces perfectly aligned
pre-drilled skins, and a very large bending brake prepares full-size
aluminum alloy sheets. Manufacturers must tool up property; otherwise
the designs are labor-intensive and at risk of financial failure,
leaving builders high and dry.
Redesigned cowlings (for engine options) are expensive to develop. Many
kitplane manufacturers provide only one design, leaving it to the
builder to make all the necessary modifications to accommodate a
different engine.
Quite a few manufacturers produce newsletters for their builders,
keeping them informed on design and construction developments.
Zenair designs have been said to be slightly more expensive than
competitive ones. But, says Heintz, "In order to remain in business for
the past 17 years, we could not allow ourselves to lose money - and we
came very close to that situation when we moved from the Toronto area to
Midland. Setup time and before-sales costs really drained our
resources."
But there's a good side to all of this: None of the 700 flying Zenair
aircraft has ever suffered a structural failure. Few companies can claim
such a record. "Because my designs meet or exceed factory aircraft
standards in Europe and North America, owners can relax with the
knowledge that the aircraft is adequate for their specific purpose,"
says Heintz.
Additionally, more and more options have been converted to standard
equipment, reflecting market preferences. Zenair kit prices generally
include more standard equipment than competitors have, and part of the
reason for this is bulk buying discounts. In other words, builders must
include all factors when comparing prices: equipment, engine,
instrumentation, and safety features.
Also, about one-third of the kit price received by Zenair is used to
finance R&D, without which no new aircraft would be forthcoming and
improvements to existing models would cease. So, probably, would the
company, in time.
When it comes to modifications proposed by owner-builders, Heintz
reviews the plans and approves them if they're safe and suitable.
Heintz no longer creates aircraft that he personally feels should be
designed. He prefers the market-research approach, visiting the major
aviation shows and talking with the public about their "wish lists". He
carries a list of all Zenair builders with him when he travels
soliciting their opinions and keeping tabs on their preferences.
"Once I decide to build a new aircraft type, it takes three years to
reach the marketplace. Two years are involved in the building process
and one in flight testing, to get the 'bugs' out. Sales are initially
slow because many builders will not get involved in something new. Only
after the first few aircraft have flown do the sales really begin. This
is a tough time for new aircraft sales - and the point when most new
companies fail."
Incidentally, it takes Zenair about 2000 man-hours to accomplish all of
the engineering calculations involved in a new design before any metal
is cut.
Zenair aircraft are essentially all-metal, because "sheet-metal aircraft
are more durable and last longer". Although aluminum alloys are
initially more expensive to buy, the maintenance costs are much lower
than with fabric-and-tube or wooden aircraft. Because metal aircraft can
be stored outside without significant deterioration, the cost of
hangaring can also be avoided. "Strange as it may seem," says Heintz,
"metal construction and 'working' rivets give obvious warning signs of
imminent structural problems. Wood and composite structures behave very
differently: the structure generally holds together up to the point of
complete failure."
Fatigue, less likely in composite structures, is well known in metal
aircraft but a qualified designer can account for it by "overdesigning"
critical parts. Zenair guarantees a 10,000-hour service life.
"Since most accidents are survivable at impact speeds below 50 mph and
few are survivable at speeds above 60 mph, designers should strive to
keep stall speeds to a maximum of 44 knots, says Heintz. "And because
many recreational pilots are unable to maintain currency on only 30-50
hours per year, their planes must be easy to fly and forgiving.
Recreational aircraft should be built for the human being's pleasure,
not for record-breaking attempts. Visibility is also very important to
provide pilot cues and, of course, avoid the risk of mid-air collision.
Too many aircraft have major blind spots.
And why not composite aircraft with their sleek compound curves? "The
major design problem with composite kits is the need for costly molds.
If the aircraft design is flawed, it is generally too expensive to make
a second or third mold, with the result that the problems are often
reproduced in each of the production aircraft."
"Some of the composite ingredients are toxic, and I know of one man who
became blind two years after he completed his aircraft. Composite
materials are like artificial wood - essentially a man-made product that
is affected by humidity and temperature changes. The composite sandwich
has a problem wherein differential heating and cooling causes the
materials to creep against each other, creating a gap that can allow
water ingestion. Freezing, cracking, and delamination can then occur,
drastically reducing the structural strength. Continued quality control
has resulted in similarly produced composite sandwiches having widely
differing properties. Even the testing can be a problem for most kit
producers, due to a lack of suitable equipment,
"Looking at an accident, I see fiberglass and wooden structures tending
to splinter, creating a war zone in the cockpit. While steel-tube
cockpit structures are much better, be sure they are heat-treated to
remove brittle areas and restore structural integrity. Nothing protects
occupants like the progressive crunching of a well-designed sheet-metal
structure. One of our CH-701s crashed directly into a vertical cliff
just short of a runway. Moments later, the pilot climbed out of the
cockpit remains and walked away, uninjured."
Some pilots think Chris Heintz designs his aircraft with an axe. Says
Heintz: "My major goals are safety, strength of structure and
pleasurable flight characteristics; the aircraft are optimized for
aerodynamic efficiency rather than visual beauty.
It was Chris Heintz (among others) who proposed the recently adopted
Aircraft Recreational Vehicle (primary) category in 1982, and the
concept was adopted very quickly by EAA. His proposal is based on the
original Zenith - which was France's first all-metal sport aircraft. The
prototype ARV was built in 1987 and, as of January 1990, qualified under
the new JAR-VLA category in Europe. The Zodiac-like craft features
side-by-side seating, tricycle gear, a low wing and dual-yoke controls.
Suitable powerplants in the 80-120-hp range include the Rotax 912,
Continental 0-200 and perhaps the Norton Rotary.
TIPS FOR BUILDERS
If readers are thinking of building a kit, here is a crash course on
correct attitudes, compliments of Chris Heintz:
"Follow the builder's manual all the way. Some builders feel competent
early in the game, with the result that they tend to forge ahead without
consulting the manual. Then I get a phone call asking, "How do I get
this aileron bellcrank in the closed wing?" Don't laugh, it's happened.
"Also, if your project has a newsletter, subscribe! They tend to be
filled with very useful building tips, sources for equipment and support
for the builder."
Chris talked briefly about progress: "People used to laugh when I
introduced 15%-thick airfoils on the Zeniths. Now, everybody is using
them. My use of 18%-thick airfoils on the Zodiac is likely to spread to
other light aircraft in five to ten years."
About the two-stroke-versus-four-stroke engine controversy: "The Wright
brothers flew with a two-stroke engine. Years ago, two strokes were easy
to build but difficult to adjust; however, the popularity of snowmobile
and boat engines has advanced the art so much that they have become
suitable as aircraft engines. The problems stem from the fact that the
engines were not designed for aircraft use and consequently were often
installed poorly.
"After three years of trial and error, Rotax is producing dependable
engines for aircraft use - but they must be maintained correctly to be
reliable (just like four-strokers). Several of our customers have more
than 1500 hours on their two-strokes. When you consider that an overhaul
on the new two-stroke Rotax 582 is about $300, you can see why I believe
it=92s a good compromise between cost and performance. The fourstroke
912
Rotax is 80 lbs. lighter than a similar Continental and just as
reliable. We have 400 hours on our first 912 and it has cost us nothing
for maintenance, thanks in part to its modem metallurgy. Although our
purchasers chose evenly between the 912 and the 582, the fourstroke 912
is 40 lbs. heavier and costs $8500.
"Although one has to be cautious with test-stand claims, I and many
others think the rotary is an engine of the future. The 90-hp rotary
from Norton is very smooth and reliable, but it is also expensive and
very noisy.
While his sons Matthew and Sebastien are running the production and
sales portions of the company, Heintz is busy trying to promote general
aviation. "Every year students from universities in Europe visit us to
study our engineering and production methods at Zenair. While we offer
the same opportunities to Canadian universities, no one seems
particularly interested in our offer. Maybe I'll write a book."
My visit to Zenair's facilities was a revelation on the matter of high
quality design, production and customer support. Canadians tend to feel
that we compare unfavorably with our neighbors to the south. However,
lest we forget, the Avro Jetliner and Arrow were well ahead of their
time in many ways. And while the country may not have been ready to
capture major markets for political reasons at that time, it seems that
our private-aircraft industry has potential to capture a significant
market share. In the case of Chris Heintz's factory, the world is
turning to Canada for guidance in the complex technology.
_____
=A9 AVIATION TODAY. Reprinted from AVIATION TODAY (Canada), pages 14 -
17, June 1991.
7:34 PM
7:34 PM
Message 45
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Rolled bead for fuel tank |
I had one of those but took it back - the amount of work that would have had to
be done top make it useful was massive. All the rollers would shear the material
just fine...
Harbor Freight sell a beading tool. I have no experience with it, but I think other
guys on this list have used it.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93364
Dave Clay
Temple, TX
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112630#112630
Dave Downey
Harleysville (SE) PA
Zodiac 601XL/Corvair?
---------------------------------
Luggage? GPS? Comic books?
Check out fitting gifts for grads at Yahoo! Search.
Message 46
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Any Michiganders going to Zenith Zip? |
I'm thinking of attending the Zenith Zip in Ontario May 19 & 20. I plan going
over early Saturday and returning some time Sunday. Port Huron is the closest
border crossing and I wondered if any other Michigan builders were thinking of
going. I'm on my own and would be happy to drive and share a motel room if
someone else wanted to ride along. We could meet up in Port Huron.
Tim Juhl
--------
DO NOT ARCHIVE
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Working on wings
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112656#112656
Message 47
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Hey Ron in San Diego,
Your construction manual, on page 10, says, "never count the + or X marking on
the drawings". Don't base the number of rivet holes on what the plans show. If
you follow Ron's advice for the crimp your stab will be just fine. Have fun!
Dave Clay
Temple, TX
http://www.daves601xl.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112657#112657
Message 48
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Word to the wise...... make sure there is no twist in the stab after you pull
the skin around and am preparing to drill into the skeleton. Read a little further
along in the pictorial guide and it tells about checking for twist by attaching
angles to the end ribs and using a spirit level. A little jig would help.
Tim
--------
DO NOT ARCHIVE
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Working on wings
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112658#112658
Message 49
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Mark - I couldn't see where the document you mentioned was attached. Could you
send it again please?
Tim
--------
DO NOT ARCHIVE
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Working on wings
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112661#112661
Message 50
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
> Your construction manual, on page 10, says, "never count the + or X
marking on the drawings". Don't base the number of rivet holes on what the
plans show. If you follow Ron's advice for the crimp your stab will be just
fine. Have fun!
But the construction standards also states "The number of rivets is given in
digits". Page 6T2 dated 03/04 says "A4 pitch 35 (13 rivets A4) end rib to
skin 6T1-1"
-- Craig
Message 51
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: New letter from Chris Heintz!! 5/11 |
Listers:
Did anyone else note the "+6/-3" g listed in the new CH letter? All the literature
I reviewed/have in my pre-purchase info package lists the rating as +/-6g.
Am I missing something here?
M2
swater6 <waters.scott@comcast.net> wrote:
For those of you with access to the builders pages, there is a new letter from
Chris addressing the recent crashes. As a recap, he is still confident in the
design the testing that has been done but he is doing the testing again to confirm.
He also has some interesting note to those now flying.
Here is the link: http://www.zenithair.com/news/c-heintz-5-10-2007.html
--------
601 XL kit
Tail, control surfaces and 1 wing complete
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=112583#112583
---------------------------------
Give spam the boot. Take control with tough spam protection
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|