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Aeronca 11AC Chief Project FS



 
 
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  #21  
Old June 23rd 08, 11:19 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Vaughn Simon
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Default Aeronca 11AC Chief Project FS


"Jim Logajan" wrote in message
.. .

I found it notable for the simple fact that it is the only CH-801 fatal
accident I could find in the NTSB database.


Yes, but I recall that it is difficult to rely on the NTSB database for
homebuilt model statistics because model designations for like aircraft are not
reliably the same. For example: somebody's CH-801 could be a "Smith 801 Rocket"
or whatever.

Vaughn


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  #22  
Old June 24th 08, 01:55 AM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Jay Maynard
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Posts: 521
Default Aeronca 11AC Chief Project FS

On 2008-06-23, Victor Bravo wrote:
You can walk up to a CH601 and move the tip of the horizontal stabilizer
fore and aft a very disturbing amount (I have on three separate aircraft).


What do you consider a "very disturbing amount"? I want to try it on my
Zodiac.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (got it!)
  #23  
Old June 24th 08, 02:22 AM posted to rec.aviation.marketplace,rec.aviation.homebuilt
john smith
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Posts: 1,446
Default Aeronca 11AC Chief Project FS

In article ,
Jay Maynard wrote:

On 2008-06-23, Victor Bravo wrote:
You can walk up to a CH601 and move the tip of the horizontal stabilizer
fore and aft a very disturbing amount (I have on three separate aircraft).


Several years ago that was discovered on the Cherokee Six that I fly.
The airplane was immediately grounded and put into maintenance to have
the bushings replaced.
  #24  
Old June 24th 08, 02:46 AM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Ron Wanttaja
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Posts: 756
Default Aeronca 11AC Chief Project FS

On Mon, 23 Jun 2008 22:19:42 GMT, "Vaughn Simon"
wrote:


"Jim Logajan" wrote in message
.. .

I found it notable for the simple fact that it is the only CH-801 fatal
accident I could find in the NTSB database.


Yes, but I recall that it is difficult to rely on the NTSB database for
homebuilt model statistics because model designations for like aircraft are not
reliably the same. For example: somebody's CH-801 could be a "Smith 801 Rocket"
or whatever.


I looked in my 1998-2006 database and found five CH-801 accidents, of which this
one was the only fatal. The five planes were registered as:

Zenith 801
CH-801
STOL CH 801
Zenith CH801
CH801

"*801*" as a search team would have picked these up. I ran "*801*" against the
total FAA registration database (Jan 4 2008 edition) and got 53 hits. Only
three planes didn't have either "CH", "Zenair", or "Zenith" as part of their
model name, and just one was obviously not a Zenith 801 (certification date in
mid-80s).

Ron Wanttaja
  #25  
Old June 24th 08, 03:06 AM posted to rec.aviation.marketplace,rec.aviation.homebuilt
clare at snyder dot ontario dot canada
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Posts: 56
Default Aeronca 11AC Chief Project FS

On Tue, 24 Jun 2008 00:55:06 GMT, Jay Maynard
wrote:

On 2008-06-23, Victor Bravo wrote:
You can walk up to a CH601 and move the tip of the horizontal stabilizer
fore and aft a very disturbing amount (I have on three separate aircraft).


What do you consider a "very disturbing amount"? I want to try it on my
Zodiac.



All considered, there is NOT a safer plane design flying than the
Zenair Zodiac 601. PERIOD. For the number sold and flying, the
fatalities have been minimal - and none have been attributed to the
design of the plane.
** Posted from http://www.teranews.com **
  #26  
Old June 24th 08, 06:51 AM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Victor Bravo
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Default Aeronca 11AC Chief Project FS

On Jun 23, 5:55 pm, Jay Maynard
wrote:
What do you consider a "very disturbing amount"? I want to try it on my
Zodiac.


Jay, I moved the tip of the stabilizer fore and aft about three
inches, which resulted in the four main stabilizer mounting tabs
moving in a twisting/shearing motion relative to each other. I first
did this on a 601XL which was built by one of our local EAA chapter
members. I thought for sure that the guy had forgotten a piece of
metal someplace. But one of our other EAA chapter members is an
engineer, he read the plans, and determined the tail attach had been
built per plans.

Then I tried to duplicate this fore-aft movement on a CH 701, which
uses a similar mounting, and was able to move it some amount as well.
Then I tried it on another 601XL which was built by the factory (QSP
in Cloverdale, CA) and was able to move the stabilizer fore and aft an
inch or two, again with the twisting/shearing motion on the stabilizer
mounting tabs.

I am definitely NOT an engineer, and cannot run any numbers or make
any authoritative statements about the structure. Chris Heintz IS an
engineer, and supposedly a very good one. But I will say that if/when
I build my 701 I will research and add some more aluminum back there
to stiffen and reinforce the structure so you can't move the stab tips
fore and aft. There are probably little or no assymetrical NORMAL
FLIGHT LOADS on it, but small movements back and forth caused by air
buffeting and vibration over some period of time can easily cause the
metal to become brittle and/or crack. Speaking as an AMATEUR mechanic,
I believe the problem is that the stabilizer mounting tabs are not
supported against bending or movement in one or two directions, and
the tabs stick up too far above the upper longeron for the off-axis
loads to be totally absorbed by the thickness of the metal.

Real engineers are more than welcome to correct me, disagree, or tell
me the problem is valid but far too small to cause a problem. Call me
a dinosaur, but I don't think you should be able to move the
stabilizer on an airplane that far fore and aft while watching the
fuselage structure twist from medium force hand movements.

And in response to what someone else posted, the 601 is not the best
or safest airplane by any stretch. The DC-3 / C-47 has a 70+ year
record of flying without ever one single structural failure.
  #27  
Old June 24th 08, 02:32 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Gig 601Xl Builder
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Posts: 683
Default Aeronca 11AC Chief Project FS

Jay Maynard wrote:
On 2008-06-23, Victor Bravo wrote:
You can walk up to a CH601 and move the tip of the horizontal stabilizer
fore and aft a very disturbing amount (I have on three separate aircraft).


What do you consider a "very disturbing amount"? I want to try it on my
Zodiac.


Jay, he's full of crap. The Horz Stab has four attach points. It doesn't
move at all unless you count the fact that the entire airplane moves
when you move it.
  #28  
Old June 24th 08, 10:11 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Jay Maynard
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Posts: 521
Default Aeronca 11AC Chief Project FS

On 2008-06-24, Victor Bravo wrote:
On Jun 23, 5:55 pm, Jay Maynard
wrote:
What do you consider a "very disturbing amount"? I want to try it on my
Zodiac.

Jay, I moved the tip of the stabilizer fore and aft about three
inches, which resulted in the four main stabilizer mounting tabs
moving in a twisting/shearing motion relative to each other.


I was not able to move mine more than a half inch at most.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (got it!)
  #29  
Old June 24th 08, 10:12 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Jay Maynard
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Posts: 521
Default Aeronca 11AC Chief Project FS

On 2008-06-24, Gig 601Xl Builder wrote:
Jay Maynard wrote:
On 2008-06-23, Victor Bravo wrote:
You can walk up to a CH601 and move the tip of the horizontal stabilizer
fore and aft a very disturbing amount (I have on three separate aircraft).

What do you consider a "very disturbing amount"? I want to try it on my
Zodiac.

Jay, he's full of crap. The Horz Stab has four attach points. It doesn't
move at all unless you count the fact that the entire airplane moves
when you move it.


Actually, mine did move a little bit, but not the three inches he said he
saw.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (got it!)
  #30  
Old June 24th 08, 10:16 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Victor Bravo
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Posts: 89
Default Aeronca 11AC Chief Project FS

On Jun 24, 6:32 am, Gig 601Xl Builder
wrote:

Jay, he's full of crap. The Horz Stab has four attach points. It doesn't
move at all unless you count the fact that the entire airplane moves
when you move it.


I am indeed full of crap sometimes, but not this time. The four attach
points that Dr. Einstein here was referring to are the exact parts
that moved slightly when I pulled on the stabilizer tip.

Here's a graphic visual example for the mechanically challenged:

Imagine that the four stabilizer mounting tabs on top of the fuselage
were all 12 inches tall, instead of the one or two inches tall that
they actually are... So the horizontal tail would be mounted a foot
above the top of the fuselage.

Under this example, when you tried to move one stabilizer tip forward
and the other one aft, it would move easily, and the four foot-long
imaginary mounting tabs would all move back and forth a little as you
twist the tail left and right (looking from above).

In order to prevent this type of movement, you would have to rivet
sheets of aluminum between these tall stabilizer supports to make the
system "torsionally stable". You would be riveting "shear webs"
between the stab supports, to oppose the shearing (and then twisting)
relative motion.

Now of course the mounting tabs are not a foot tall, so you cannot
swing the stabilizer tip fore and aft with one finger like you could
if it was a foot tall. But the stabilizer mounting tabs ARE an inch or
two above the fuselage, and this distance is NOT braced in shear or
twisting. So you CAN move it fore and aft a little, and when you do
this you CAN see the mounting tabs move relative to each other a
little.

Ladies and Gentlemen, you CANNOT move the stabilizer back and forth
this way on an undamaged Cessna, Taylorcraft, Champ, or Beech. You
cannot do it on a Luscombe, you cannot do it on an undamaged Piper
Cherokee, and you cannot do it on a Maule and you cannot do it on a
Grumman Yankee. I can go on if I have not made the point clearly
enough.

The stabilizer mounting system on the 601 and possibly the 701 is in
my opinion not rigid enough. The tabs are not braced against shearing
or twisting. There is no reason you should be able to move the
stabilizer back and forth on a standard configuration light aircraft
like that. When you move it like this, you are slightly bending the
stabilizer mounting tabs (and the attach structure on the fuselage)
back and forth a little bit each time.
 




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