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BobCollins
Joined: 12 Aug 2008
Posts: 19
Location: Sunnyvale CA USA
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 Posted: Sat Apr 18, 2009 4:50 pm Post subject: Zenith Family Problems? |
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I have a question for you long-time STOL aficionados. Is there any
reason to worry about flutter of the flaperon on the Zenith STOL designs?
I have been following the "discussion" about potential 601XL aileron
flutter problems on the Zenith-List. One point seems to come through is
that using a mass-balanced aileron is a relatively common practice in
modern designs to reduce/eliminate flutter and, apparently, the 601XL
depends on proper tension on the control cables to satisfy this need
(Zenith has stated this). My personal observation is that, if what I
just stated is true, using mass-balanced ailerons would be preferable
because they require less frequent inspection and oversight.
My current interest is in the CH750, which of course has no history
other than what may be extrapolated from the 701 and 801. I don't see
any evidence of mass-balancing on the STOL models. Now, in many ways the
STOL planes are different than the 600 series designs, but is there any
reason to worry about similar issues on the 750? My first pass
observation is that the STOL planes are slower, have heavier control
surfaces, and the flaperon linkage (probably) has more inherent mass.
These would all point to flutter being less likely a problem on the STOL
designs that on the 600 designs.
In addition to concern about any (potential) real design issues, there
is the effect this whole issue might have on the reputation of Zenith
and the Zenith designs. A strong selling point for the Zenith designs is
the sterling reputation of the chief designer. If there are valid
criticisms of his design choices, particularly in an area that affects
safety, this would affect the whole Zenith ecosystem.
I am interested in your thoughts. Also, for those of you going to
Sun'N'Fun, please report anything you learn that would be of help to us
in the Zenith STOL community.
Thank you,
Bob Collins
Sunnyvale CA USA
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craig(at)craigandjean.com
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| Posted: Sat Apr 18, 2009 5:02 pm Post subject: Zenith Family Problems? |
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Well, the 701 has been flying for a lot longer than the 601XL. I believe
that there hadn't been a fatal accident in the US until a year or two ago
when a new owner died doing some inappropriate low-level maneuvers in front
of his family.
-- Craig (incomplete 601XL and 701)
--
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dougsnash
Joined: 14 Apr 2008
Posts: 281
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| Posted: Sat Apr 18, 2009 6:21 pm Post subject: Zenith Family Problems? |
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Bob, I am by no means an aeronautical engineer but my thumbnail engineering opinion would be becasue of the mounting method of the flapperons on the STOL design, they have semi mass balanced flapperons. Since they are mounted on the flapperon spar line, there is a significant portion of their mass infront of the mounting point.
Do Not Archive
Doug MacDonald
CH-701 Scratch builder
NW Ontario, Canada
| Quote: | I have a question for you long-time STOL aficionados. Is
there any reason to worry about flutter of the flaperon on
the Zenith STOL designs?
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bob(at)frontrange-pc.com
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| Posted: Sat Apr 18, 2009 8:32 pm Post subject: Zenith Family Problems? |
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Bob,
I'm no expert, but a quick browse of the NTSB accident database over the
last 20 years returned 27 '701' accidents. As Craig said, only one
fatality and a quick read of the probable cause on that accident would
not lead you to suspect the design. I saw no mention of flutter or
vibration in any of the reports. However, it appears that dead stick
landing technique might be worth practicing.
Bob Percival
701/Vair
--
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john.marzulli(at)gmail.co
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| Posted: Sat Apr 18, 2009 8:53 pm Post subject: Zenith Family Problems? |
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Our EAA chapter is lucky to have Ron Wantaja speak to us from time to time.
I asked him once if he had found anything interesting about Zeniths during his safety studies. His insight was the Zeniths have a much higher rate of auto-conversions engines. When you subtract out the autoconversion accidents, the fleet safety is much better than the EAB average. The engine failures are more likely the result of the R&D part of creating a new conversion/installation than anything else.
Personally I am planning on have more than a few people look over my Rotax installation.
Safe flying.
John Marzulli
http://www.GenevieveMarzulli.org/
http://marzulli.smugmug.com/
http://701Builder.blogspot.com/
http://www.JohnMarzulli.net/
On Sat, Apr 18, 2009 at 9:49 PM, Bob Percival <bob(at)frontrange-pc.com (bob(at)frontrange-pc.com)> wrote:
[quote]--> Zenith701801-List message posted by: "Bob Percival" <bob(at)frontrange-pc.com (bob(at)frontrange-pc.com)>
Bob,
I'm no expert, but a quick browse of the NTSB accident database over the
last 20 years returned 27 '701' accidents. As Craig said, only one
fatality and a quick read of the probable cause on that accident would
not lead you to suspect the design. I saw no mention of flutter or
vibration in any of the reports. However, it appears that dead stick
landing technique might be worth practicing.
Bob Percival
701/Vair
--
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Tommy Walker
Joined: 12 Jan 2006
Posts: 442
Location: Anniston, AL 36207
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| Posted: Sun Apr 19, 2009 6:04 am Post subject: Zenith Family Problems? |
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I think the entire rigging of the Flaperon system in the 701 makes it resistant to flutter, provided the operator insures the linkage is secure. Steel rods tend to not lose their tension J .
Also, the slow speed and drag should mitigate against flutter, again provided the various components are secure.
However, I’m not an aeronautical engineer, though I’ve spent many nights in the HI Express chain.
Tommy Walker
Building 701 #2 and have eyes on a 750.
Definitely Do Not Archive
The term [i]mayday[/i] used for signaling for help (after SOS), comes from the French word [i]m'aidez[/i], which is pronounced "may day" and means "Help Me."
[quote][b]
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_________________
Tommy Walker
N25A - Anniston, AL |
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dwilde(at)clearwire.net
Guest
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| Posted: Sun Apr 19, 2009 8:14 am Post subject: Zenith Family Problems? |
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Yesterday I had my 701 at 102 mph and hit light turbulence at which
point I slowed down. There was no shaking or flutter of anything. It was
solid as a rock.
Dan Wilde
N948DW
Tommy Walker wrote:
| Quote: |
I think the entire rigging of the Flaperon system in the 701 makes it
resistant to flutter, provided the operator insures the linkage is
secure. Steel rods tend to not lose their tension J .
Also, the slow speed and drag should mitigate against flutter, again
provided the various components are secure.
However, I’m not an aeronautical engineer, though I’ve spent many
nights in the HI Express chain.
Tommy Walker
Building 701 #2 and have eyes on a 750.
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ggower_99(at)yahoo.com
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| Posted: Sun Apr 19, 2009 9:28 pm Post subject: Zenith Family Problems? |
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Dead stick landing technique is a must to practice in ALL airplanes. Here is part of our training, once "learned" should be practiced.
Might save your life, if any doubt, just ask the Hudson River Pilots.
Get some glider training will do you no harm.
Saludos
Gary Gower
Flying from Chapala, Mexico
701 912S
2 cycle engined ultralights "survivor" 
--- On Sun, 4/19/09, Bob Percival <bob(at)frontrange-pc.com> wrote:
[quote]From: Bob Percival <bob(at)frontrange-pc.com>
Subject: RE: Zenith Family Problems?
To: zenith701801-list(at)matronics.com
Date: Sunday, April 19, 2009, 12:49 AM
[quote]--> Zenith701801-List message posted by: "Bob Percival" <bob(at)frontrange-pc.com> Bob, I'm no expert, but a quick browse of the NTSB accident database over the last 20 years returned 27 '701' accidents. As Craig said, only one fatality and a quick read of the probable cause on that accident would not lead you to suspect the design. I saw no mention of flutter or vibration in any of the reports. However, it appears that dead stick landing technique might be worth practicing. Bob Percival 701/Vair --
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ggower_99(at)yahoo.com
Guest
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| Posted: Sun Apr 19, 2009 9:35 pm Post subject: Zenith Family Problems? |
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Hello Dan,
Getting ready for the San Diego Red Bull Race?
Saludos
Gary Gower
Do not archive.
--- On Sun, 4/19/09, Dan Wilde <dwilde(at)clearwire.net> wrote:
| Quote: | From: Dan Wilde <dwilde(at)clearwire.net>
Subject: Re: Zenith Family Problems?
To: zenith701801-list(at)matronics.com
Date: Sunday, April 19, 2009, 12:13 PM
| Quote: | --> Zenith701801-List message posted by: Dan Wilde
<dwilde(at)clearwire.net>
Yesterday I had my 701 at 102 mph and hit light turbulence at which point I
slowed down. There was no shaking or flutter of anything. It was solid as a
rock.
Dan Wilde
N948DW
Tommy Walker wrote:
| Quote: |
I think the entire rigging of the Flaperon system in the 701 makes it
resistant to flutter, provided the operator insures the linkage is secure. Steel
|
rods tend to not lose their tension J .
| Quote: |
Also, the slow speed and drag should mitigate against flutter, again
provided the various components are secure.
|
| Quote: |
However, I’m not an aeronautical engineer, though I’ve spent many
nights in the HI Express chain.
|
| Quote: |
Tommy Walker
Building 701 #2 and have eyes on a 750.
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[quote][b]
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