Today's Message Index:
----------------------
1. 04:48 AM - Re: New Nose Gear Leg & Fork Shimmy Issue (Dale Walter)
2. 07:19 AM - Want to buy RV4 (John Morgensen)
3. 08:27 AM - Nose wheel axle torque (PSPRV6A@aol.com)
4. 08:28 AM - Re: New Nose Gear Leg & Fork Shimmy Issue (Robin Marks)
5. 08:56 AM - Re: New Nose Gear Leg & Fork Shimmy Issue (mike humphrey)
6. 08:56 AM - Re: Nose wheel axle torque (Scott)
7. 09:08 AM - Re: New Nose Gear Leg & Fork Shimmy Issue (linn Walters)
8. 09:26 AM - Re: New Nose Gear Leg & Fork Shimmy Issue (Ron Lee)
9. 09:45 AM - Re: New Nose Gear Leg & Fork Shimmy Issue (Ron Lee)
10. 03:48 PM - Re: Nose wheel axle torque (Dave Nellis)
11. 06:27 PM - New Nose Gear Leg & Fork Shimmy Issue (Ralph Hoover)
Message 1
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| Subject: | New Nose Gear Leg & Fork Shimmy Issue |
OK, then remove the tire and fly the plane. If the shimmy is still there you
have proved your case. BTW, except for the hub, the tire is the only moving
part at the end of the leg unless your tire is not perfect. The wheel
fairing will not create shimmy, it is always the victim. Tires change, and
can go bad any time; forget about how it was before the shimmy. The poster
who questioned greasing has a good point. Also, maybe that super landing of
yours got grease on it (greaser).
Good luck,
Dale
_____
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Robin Marks
Sent: Friday, February 08, 2008 1:14 AM
Subject: RE: RV-List: New Nose Gear Leg & Fork Shimmy Issue
I am fairly sure the shimmy is unrelated to a tire issue as I have had zero
issues with the exact same tire before the annual (0.2 hours ago). I will
test the rotation in the AM. I have read about the axel nut torque in the
past so I will check that too.
When I let the front wheel down it was not a drop but rather a near perfect
landing right before the violent shimmy.
Thanks,
Robin
Message 2
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I am looking to buy a nice flying RV4. I am located in the Reno, NV area
but can travel as necessary. Any help would be appreciated.
John Morgensen
775 771-5791
Message 3
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| Subject: | Nose wheel axle torque |
On the 6A my son Eric & I are completing, we chose to put a spacer between
the inner races of the tapered roller bearings. This permits the axle nut to
be fully tightened without overloading the bearings.
Having a metal lathe in our shop made it simple to trim the spacer to
exactly the right length. If you have easy access to a lathe, it is a
worthwhile improvement.
Paul s. Petersen, Minnetonka MN
**************Biggest Grammy Award surprises of all time on AOL Music.
(http://music.aol.com/grammys/pictures/never-won-a-grammy?NCID=aolcmp003000000025
48)
Message 4
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| Subject: | New Nose Gear Leg & Fork Shimmy Issue |
>And your castoring "breakout" force is still the same?
I doubt as it's a new gear leg & fork. I will have to check & re-set.
>Is the mounting hole to the engine mount getting sloppy?
No, this is a new gear leg and the drilled hole is perfect.
> Did you over grease the pivot joint?
I don't have the repairman's certificate on this plane so the annual was
performed by a mechanic. I will go out to the airport and check today.
Thanks for everyone's help so far.
Robin
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of
Vanremog@aol.com
Sent: Thursday, February 07, 2008 10:47 PM
Subject: Re: RV-List: New Nose Gear Leg & Fork Shimmy Issue
In a message dated 2/7/2008 10:18:26 P.M. Pacific Standard Time,
robin1@mrmoisture.com writes:
I am fairly sure the shimmy is unrelated to a tire issue as I
have had zero issues with the exact same tire before the annual (0.2
hours ago). I will test the rotation in the AM. I have read about the
axle nut torque in the past so I will check that too.
When I let the front wheel down it was not a drop but rather a
near perfect landing right before the violent shimmy.
=====================
And your castoring "breakout" force is still the same? Did you over
grease the pivot joint? Is the mounting hole to the engine mount
getting sloppy?
N1GV (RV-6A, Flying 883hrs, O-360-A1A, C/S, Silicon Valley)
________________________________
Who's never won? Biggest Grammy Award surprises of all time on AOL
Music.
<http://music.aol.com/grammys/pictures/never-won-a-grammy?NCID=aolcmp00
3
00000002548>
Message 5
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| Subject: | Re: New Nose Gear Leg & Fork Shimmy Issue |
Change tire is good idea-eliminate the obvious. Bearings go bad also,
especially if too much or too little grease. Try one thing at a time,
you'll find the issue as to why, hopefully it will be sooner then later.
Mike H
----- Original Message -----
From: Dale Walter
To: rv-list@matronics.com
Sent: Friday, February 08, 2008 7:40 AM
Subject: RE: RV-List: New Nose Gear Leg & Fork Shimmy Issue
OK, then remove the tire and fly the plane. If the shimmy is still
there you have proved your case. BTW, except for the hub, the tire is
the only moving part at the end of the leg unless your tire is not
perfect. The wheel fairing will not create shimmy, it is always the
victim. Tires change, and can go bad any time; forget about how it was
before the shimmy. The poster who questioned greasing has a good point.
Also, maybe that super landing of yours got grease on it (greaser).
Good luck,
Dale
-------------------------------------------------------------------------
-----
From: owner-rv-list-server@matronics.com
[mailto:owner-rv-list-server@matronics.com] On Behalf Of Robin Marks
Sent: Friday, February 08, 2008 1:14 AM
To: rv-list@matronics.com
Subject: RE: RV-List: New Nose Gear Leg & Fork Shimmy Issue
I am fairly sure the shimmy is unrelated to a tire issue as I have had
zero issues with the exact same tire before the annual (0.2 hours ago).
I will test the rotation in the AM. I have read about the axel nut
torque in the past so I will check that too. When I let the front wheel
down it was not a drop but rather a near perfect landing right before
the violent shimmy. Thanks,Robin
http://www.matronics.com/contribution
Message 6
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| Subject: | Re: Nose wheel axle torque |
Or maybe someone could start a little side business making them
available to RVers ;) Of course, I won't need them for my RV-4 ;)
Speaking of lathes, I'd love to have one. What do listers who own
lathes recommend for a general purpose, non-wallet busting lathe??
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)
PSPRV6A@aol.com wrote:
> On the 6A my son Eric & I are completing, we chose to put a
> spacer between the inner races of the tapered roller bearings. This
> permits the axle nut to be fully tightened without overloading the
> bearings.
> Having a metal lathe in our shop made it simple to trim the spacer
> to exactly the right length. If you have easy access to a lathe, it is
> a worthwhile improvement.
>
Paul
> s. Petersen, Minnetonka MN
>
>
> ------------------------------------------------------------------------
> Who's never won? Biggest Grammy Award surprises of all time on AOL
> Music.
> <http://music.aol.com/grammys/pictures/never-won-a-grammy?NCID=aolcmp00300000002548>
>
>
Message 7
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| Subject: | Re: New Nose Gear Leg & Fork Shimmy Issue |
I don't think so. Out of round will cause the nose fork to bounce, not
shimmy. Shimmy being a side to side motion. Tighten up on the nut that
holds the nose fork on. The Grummans use belleville washers to create
the drag necessary to prevent the shimmy. I don't know about the RV
gears. To adjust the Grumman nose gear, you apply a spring scale to the
wheel axle and torque the nut 'till the spring scale exerts at least 25
Lbs pull before the gear swivels. With the tire off the ground, of
course! ;-)
Linn
Ron Lee wrote:
> The two most likely issues are out of balance and out of round. Since
> it is a new tire I would guess out of balance. It is easy to tell the
> difference
> between one or both of those and shimmy from the outside while taxiing
>
> Ron Lee
>
>
Message 8
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| Subject: | Re: New Nose Gear Leg & Fork Shimmy Issue |
Ok, listen closely. You need to have someone observe your tires while
you get
what you call a shimmy. Look from the front and from the side. A
competent
observer will be able to tell if it is shimmy or out of balance/out of
round.
Once that is determined you can determine which of the possible fixes
works.
Ron
----- Original Message -----
From: Robin Marks
To: rv-list@matronics.com
Sent: Thursday, February 07, 2008 11:13 PM
Subject: RE: RV-List: New Nose Gear Leg & Fork Shimmy Issue
I am fairly sure the shimmy is unrelated to a tire issue as I have had
zero issues with the exact same tire before the annual (0.2 hours ago).
I will test the rotation in the AM. I have read about the axel nut
torque in the past so I will check that too. When I let the front wheel
down it was not a drop but rather a near perfect landing right before
the violent shimmy. Thanks,Robin
Message 9
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| Subject: | Re: New Nose Gear Leg & Fork Shimmy Issue |
Linn, the problem is that whenever someone gets a vibration of any sort
the immediate
assumed problem is SHIMMY. Unless someone confirms visually that it is
a shimmy
the original poster may be chasing the wrong problem. I have had these
problems and
chased shimmy causal factors until I had someone videotape the nose
wheel and it
was immediately obvious that it was not shimmy, but out of round/out of
balance.
Heck it may be a main wheel/tire so the simple step of visually seeing
what is happening
when the problem is felt can save a lot of time.
Ron
----- Original Message -----
From: linn Walters
To: rv-list@matronics.com
Sent: Friday, February 08, 2008 10:02 AM
Subject: Re: RV-List: New Nose Gear Leg & Fork Shimmy Issue
I don't think so. Out of round will cause the nose fork to bounce,
not shimmy. Shimmy being a side to side motion. Tighten up on the nut
that holds the nose fork on. The Grummans use belleville washers to
create the drag necessary to prevent the shimmy. I don't know about the
RV gears. To adjust the Grumman nose gear, you apply a spring scale to
the wheel axle and torque the nut 'till the spring scale exerts at least
25 Lbs pull before the gear swivels. With the tire off the ground, of
course! ;-)
Linn
Ron Lee wrote:
The two most likely issues are out of balance and out of round.
Since
it is a new tire I would guess out of balance. It is easy to tell
the difference
between one or both of those and shimmy from the outside while
taxiing
Ron Lee
Message 10
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| Subject: | Re: Nose wheel axle torque |
I have an Enco 10 x 36 lathe in my basement. I also
have a 9 x 26 knee type (Bridgeport similar) mill.
Both have digital readouts. They are both great for
hobbyists and small work.
I have been building a nine cylinder radial engine on
these machines but RV building has been getting the
attention lately.
I am always looking for sidework, especially for RV
work. We have just moved into a new house and the
lathe and mill are in pieces. About a month I will be
up and running.
Dave
--- Scott <acepilot@bloomer.net> wrote:
> <acepilot@bloomer.net>
>
> Or maybe someone could start a little side business
> making them
> available to RVers ;) Of course, I won't need them
> for my RV-4 ;)
>
> Speaking of lathes, I'd love to have one. What do
> listers who own
> lathes recommend for a general purpose, non-wallet
> busting lathe??
>
> Scott
> http://corbenflyer.tripod.com/
> Gotta Fly or Gonna Die
> Building RV-4 (Super Slow Build Version)
>
>
>
> PSPRV6A@aol.com wrote:
>
> > On the 6A my son Eric & I are completing, we
> chose to put a
> > spacer between the inner races of the tapered
> roller bearings. This
> > permits the axle nut to be fully tightened without
> overloading the
> > bearings.
> > Having a metal lathe in our shop made it
> simple to trim the spacer
> > to exactly the right length. If you have easy
> access to a lathe, it is
> > a worthwhile improvement.
> >
> Paul
> > s. Petersen, Minnetonka MN
> >
> >
> >
> >
>
------------------------------------------------------------------------
> > Who's never won? Biggest Grammy Award surprises of
> all time on AOL
> > Music.
> >
>
<http://music.aol.com/grammys/pictures/never-won-a-grammy?NCID=aolcmp00300000002548>
> >
> >
> >
> >
> >
>
>
> browse
> Un/Subscription,
> FAQ,
>
> Forums!
>
> Admin.
>
>
>
>
>
Never miss a thing. Make Yahoo your home page.
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Message 11
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| Subject: | New Nose Gear Leg & Fork Shimmy Issue |
Troubleshooting 101 says that if you change one variable and something
bad happens change it back!! In this case the most likely change was the
drag on the fork to strut bearing. The tire although it could have
changed probably not likely. Shimmy is more related to geometry and the
damping in the system it appears. I'm not an expert so look at this NACA
study on the subject and draw your own conclusion. The first thing I
would do is check the fork drag is to Van's spec
http://tinyurl.com/399cjn
Stability of castering wheels for aircraft landing gears
<http://ntrs.nasa.gov/search.jsp?R=849502&id=2&qs=Ntt%3DShimmy%26R%3D849502%26Ntk%3Dall%26qs%3DNo%26Ntx%3Dmode%2520matchall%26Ns%3DHarvestDate%257c1%26N%3D0%26id%3D2>
Author(s): Kantrowitz, Arthur
Abstract: A theoretical study was made of the *shimmy* of castering
wheels. The theory is based on the discovery of a phenomenon called
kinematic *shimmy*. Experimental checks, use being made of a model
having low-pressure ...
NASA Center: Langley Research Center
Publication Year: 1940
Added to NTRS: 2006-11-06
Accession Number: 93R21053; Document ID: 19930091763; Report Number:
NACA-TR-686
--
Ralph C. Hoover
RV7A
hooverra at verizon dot net
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