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msausen
Joined: 25 Oct 2007
Posts: 559
Location: Appleton, WI USA
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 Posted: Fri Feb 26, 2010 11:23 am Post subject: vibration in mains on roll out |
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More mass and different materials to absorb the vibrations and convert it to something else like heat. Same principals used in deadening sound.
Michael
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ricksked(at)cox.net
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| Posted: Fri Feb 26, 2010 12:01 pm Post subject: vibration in mains on roll out |
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Is that some sort of an attempt to quantify your understanding of the problem? ..Mine came on progressively so I am leaning towards the tire as the main cause, Don is here now and he swears that was the fix for him..if it were a gear specific issue I would think it would have been there from the beginning right?
Sent via BlackBerry by AT&T
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partner14
Joined: 12 Jan 2008
Posts: 540
Location: Granbury Texas
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| Posted: Fri Feb 26, 2010 12:21 pm Post subject: vibration in mains on roll out |
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Rick is at least partially correct... what I think may have happenned was through lots of, ok and not so ok landings, the balance in the tires simply got worse and worse. That imbalance feeds back through the gear legs, then at some point, they are unable to remain stable, and begin to shimmy. What I do know, is that it sure feels wonderful to be shimmy free.... and I promise to make all my landings in the future, perfect! (--;
Don McDonald
--- On Fri, 2/26/10, ricksked(at)cox.net <ricksked(at)cox.net> wrote:
[quote]
From: ricksked(at)cox.net <ricksked(at)cox.net>
Subject: Re: Re: vibration in mains on roll out
To: rv10-list(at)matronics.com
Date: Friday, February 26, 2010, 11:55 AM
--> RV10-List message posted by: ricksked(at)cox.net (ricksked(at)cox.net)
Is that some sort of an attempt to quantify your understanding of the problem? ..Mine came on progressively so I am leaning towards the tire as the main cause, Don is here now and he swears that was the fix for him..if it were a gear specific issue I would think it would have been there from the beginning right?
Sent via BlackBerry by AT&T
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_________________
Don A. McDonald
40636 |
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pitts_pilot(at)bellsouth.
Guest
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| Posted: Fri Feb 26, 2010 1:10 pm Post subject: vibration in mains on roll out |
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I'd like to see some 'standard' for describing the antics of the landing
gear.
I refer to shimmy as the action of the nosewheel and tailwheels when
they act like a crippled shopping cart. That being a side-to side
castering. Cure is to tighten the spindle nut on the nosegear or
changing the angle of the tailwheel spindle.
As for the mains ... 'walking' would be the fore/aft movement as the
airplane rolls .... caused by many things. Caster (the way the wheel
center line points), brake rotor wobble (changing drag on the rotor) and
loose wheel bearings will cause this. There may be others that I
haven't come across.
The other antic is hop. Out of balance or out of round is the typical
cause.
Since we perceive all of the antics as an airframe vibration, the only
way to really tell is to get a pair of eyeballs to watch as you land to
see what's really going on.
I've heard of (but never seen) putting a hardwood fairing behind the
main gear to stiffen it to remove the 'walking'.
I'd also really like to see more discussion on gear issues from those
that have been there.
Linn
Don McDonald wrote:
| Quote: | Rick is at least partially correct... what I think may have happenned
was through lots of, ok and not so ok landings, the balance in the tires
simply got worse and worse. That imbalance feeds back through the gear
legs, then at some point, they are unable to remain stable, and begin to
shimmy. What I do know, is that it sure feels wonderful to be shimmy
free.... and I promise to make all my landings in the future,
perfect! (--;
Don McDonald
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rv10flyer
Joined: 25 Aug 2009
Posts: 364
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| Posted: Fri Feb 26, 2010 1:40 pm Post subject: Re: vibration in mains on roll out |
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Linn, I have seen that done on a Harmon Rocket. That is what made me think of the carbon fiber as long as it fits underneath the stock leg fairings. It is nice to see everyones ideas/comments on here.
Don, I like the "rough landings, leading to out of round/balance condition, then leading to the vibration". I just wish the tapered rod gear legs were not so sensitive, because my 172 landings are not perfect(I wish I could say they were).
I actually had more fun, had a better view and landings seemed a little easier with my friends RV-9A. Have not done one in the -10. Just the demo ride last year at snf with Joe Blank.
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Wayne G. |
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ricksked(at)cox.net
Guest
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| Posted: Fri Feb 26, 2010 2:15 pm Post subject: vibration in mains on roll out |
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One thing I want to point out is if I allow the aircraft to roll out until taxi speed then apply the brakes there isn't any wheel hop/vibration/shimmy or cocoa bop.. I HAVEN'T ruled out brake chatter/grab except it does not occur stopping from slow speeds...Now my theory is that when applying the brakes "hard" to make the requested turn off causes the gear legs to move aft increasing the toe out and causing the wheel to seek "it's" true track. The energy stored in the gear leg overcomes the tire and in effect the swinging steel ball pendulum starts to occur. I'm not so sure you will realize enough stiffness with a composite or wood backing. Redesigning the gear into a flat shape rather than the cylindrical that currently is in use may be the answer. Anyone get similar results off grass? Grass would allow the tire to slide rather than trying to get back in line with the track of the aircraft. Just brainstorming...
---
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msausen
Joined: 25 Oct 2007
Posts: 559
Location: Appleton, WI USA
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rv10builder(at)verizon.ne
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| Posted: Fri Feb 26, 2010 3:45 pm Post subject: vibration in mains on roll out |
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I have to think if the step gets to the point that many want to have an
access panel to resolve it that the gear may be the same issue.
Specifically, the bolt tends to become looser each time someone kicks off
the step or the gear absorbs the perfect landings causing it to slowly get
more loose.
Don has a resolution to his by replacing the tires and balancing them, that
may be the solution but there may be others, I am watching this issue
closely as there are far more complains about the gear than there are about
the doors flying off, yet Vans has never heard of this issue before anyone
calls them on it. BTW- Scott at Vans support has been straight up with me,
he's told me he knows of issues, has always given a suggestion and never
told me I was the first to tell him about it, never seems to even cross his
mind.. I would encourage some to give Vans a call and see if they have any
suggestions, maybe enough calls and they may pursue a solution.
--------------------------------------------------
From: <ricksked(at)cox.net>
Sent: Friday, February 26, 2010 11:55 AM
To: <rv10-list(at)matronics.com>
Subject: Re: Re: vibration in mains on roll out
[quote]
Is that some sort of an attempt to quantify your understanding of the
problem? ..Mine came on progressively so I am leaning towards the tire as
the main cause, Don is here now and he swears that was the fix for him..if
it were a gear specific issue I would think it would have been there from
the beginning right?
Sent via BlackBerry by AT&T
--
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Tim Olson
Joined: 25 Jan 2007
Posts: 2881
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| Posted: Fri Feb 26, 2010 4:10 pm Post subject: vibration in mains on roll out |
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Nope....this one is just due to round gear legs. No big deal. Far
more an annoyance (minor) than a big deal. Start by balancing
everything and most people will be pretty ok. Some may have
variations of issues that make it less ok. But it's not an
overwhelming problem.
Tim
On Feb 26, 2010, at 5:34 PM, "Pascal" <rv10builder(at)verizon.net> wrote:
[quote]
I have to think if the step gets to the point that many want to have
an access panel to resolve it that the gear may be the same issue.
Specifically, the bolt tends to become looser each time someone
kicks off the step or the gear absorbs the perfect landings causing
it to slowly get more loose.
Don has a resolution to his by replacing the tires and balancing
them, that may be the solution but there may be others, I am
watching this issue closely as there are far more complains about
the gear than there are about the doors flying off, yet Vans has
never heard of this issue before anyone calls them on it. BTW- Scott
at Vans support has been straight up with me, he's told me he knows
of issues, has always given a suggestion and never told me I was the
first to tell him about it, never seems to even cross his mind.. I
would encourage some to give Vans a call and see if they have any
suggestions, maybe enough calls and they may pursue a solution.
--------------------------------------------------
From: <ricksked(at)cox.net>
Sent: Friday, February 26, 2010 11:55 AM
To: <rv10-list(at)matronics.com>
Subject: Re: Re: vibration in mains on roll out
>
>
> Is that some sort of an attempt to quantify your understanding of
> the problem? ..Mine came on progressively so I am leaning towards
> the tire as the main cause, Don is here now and he swears that was
> the fix for him..if it were a gear specific issue I would think it
> would have been there from the beginning right?
> Sent via BlackBerry by AT&T
>
> --
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40950(at)rv10.net
Guest
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| Posted: Fri Feb 26, 2010 4:44 pm Post subject: vibration in mains on roll out |
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An engineering look at the problem (I got this off the web). My comments below the math:
http://en.wikipedia.org/wiki/Fundamental_frequency
Consider a beam, fixed at one end and having a mass attached to the other, this would be a single degree of freedom (SDoF) oscillator. Once set into motion it will oscillate at its natural frequency. For a single degree of freedom oscillator, a system in which the motion can be described by a single coordinate, the natural frequency depends on two system properties; mass and stiffness. The radian frequency, ωn, can be found using the following equation:
Where:
k = stiffness of the beam
m = mass of weight
ωn = radian frequency (radians per second)
The stiffness, k, of a body is a measure of the resistance offered by an elastic body to deformation (bending, stretching or compression).
where
P is a steady force applied on the body
δ is the displacement produced by the force (for instance, the deflection of a beam, or the change in length of a stretched spring)
From the radian frequency, the natural frequency, fn, can be found by simply dividing ωn by 2π. Without first finding the radian frequency, the natural frequency can be found directly using:
Where:
fn = natural frequency in hertz (cycles/second)
k = stiffness of the beam (Newtons/Meter or N/m)
m = mass of weight (kg) while doing the modal analysis of structures and mechnical equipments, the frequency of 1st mode is called fundamental frequency.
==================
My thoughts: The landing gear may have a natural frequency around the 40 mph or so speed some have experienced. At that speed, without much energy required to excite the harmonic or resonance response, it doesn't take much to cause a noticeable vibration (out of alignment, out of balance, surface condition, gear loading due to gross weight, etc). The wheel rpm at the offending speed could give us a clue as to the natural frequency. That is frequency = velocity/tire circumference. Then work the rest of the formulas backwards to determine theoretical mass and maybe even do some stiffness measurements on the gear leg. Might get close, might not but the goal here is to get a look at what it would take to move the natural frequency around until it is no longer excited during the takeoff or landing phase while on the ground.
Adding more weight, like a heavier tire, could conceivably lower the natural frequency to the point where the natural damping of the steel gear leg is such that at a lower speed the rotating wheel can no longer excite the harmonic mode. Same goes for stiffening the gear leg with carbon or wood: it may raise the frequency and damping factor such that the mode again cannot be excited at the new condition. Classic spring mass damper solution of sorts.
Perfect alignment, perfect balance, perfectly smooth landings and runways would probably not excite the harmonic on roll-out. But we all know these conditions don't last very long. So the answer is probably some combination of straight gear (aligned), better damping (carbon stiffener or other mod on to the gear leg to either raise the natural frequency, damping or both), and balanced wheels and tires.
Sorry for all the formulas but it helped me think it out out,
Tom
#40950 waiting for long build wings.
Crestview, FL
On Feb 26, 2010, at 5:34 PM, Pascal wrote:
| Quote: |
I have to think if the step gets to the point that many want to have an access panel to resolve it that the gear may be the same issue. Specifically, the bolt tends to become looser each time someone kicks off the step or the gear absorbs the perfect landings causing it to slowly get more loose.
Don has a resolution to his by replacing the tires and balancing them, that may be the solution but there may be others, I am watching this issue closely as there are far more complains about the gear than there are about the doors flying off, yet Vans has never heard of this issue before anyone calls them on it. BTW- Scott at Vans support has been straight up with me, he's told me he knows of issues, has always given a suggestion and never told me I was the first to tell him about it, never seems to even cross his mind.. I would encourage some to give Vans a call and see if they have any suggestions, maybe enough calls and they may pursue a solution.
--------------------------------------------------
From: <ricksked(at)cox.net>
Sent: Friday, February 26, 2010 11:55 AM
To: <rv10-list(at)matronics.com>
Subject: Re: Re: vibration in mains on roll out
|
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ricksked(at)cox.net
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ricksked(at)cox.net
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| Posted: Fri Feb 26, 2010 5:19 pm Post subject: vibration in mains on roll out |
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Ok...you win obviously an engineer quantifying his findings....I remember all that stuff " heh yeah right" just never figured I'd use it in real life...knew I should have paid better attention!!! Good show old man.... But you're like 20 years old right? How bout substituting numerical values to gear leg, mass and resonance and other stuff like that, not being anything other than becoming hungry for more knowledge
Sent via BlackBerry by AT&T
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40950(at)rv10.net
Guest
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| Posted: Fri Feb 26, 2010 5:47 pm Post subject: vibration in mains on roll out |
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I only wish I was 20 yrs. Aero engr, class of 76, A&M. I'm only getting ready to do wings but if I get to the gear later and we are still having issues with vibration, I know I'll work the problem. Maybe there are others out there with gear interested in doing some measurements. I know there are some young engr bucks out there with brains that work better than mine to do the math. And probably have access to some really cool simulation applications on which to do the analysis.
Tom
#40950
Gig 'em.
On Feb 26, 2010, at 7:09 PM, ricksked(at)cox.net wrote:
[quote]
Ok...you win obviously an engineer quantifying his findings....I remember all that stuff " heh yeah right" just never figured I'd use it in real life...knew I should have paid better attention!!! Good show old man.... But you're like 20 years old right? How bout substituting numerical values to gear leg, mass and resonance and other stuff like that, not being anything other than becoming hungry for more knowledge
Sent via BlackBerry by AT&T
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ricksked(at)cox.net
Guest
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| Posted: Fri Feb 26, 2010 6:23 pm Post subject: vibration in mains on roll out |
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Tom,
I will measure you do the math...let me know what you need and maybe we can provide a definitive answer to this problem...we don't need no stinkin computer models...they get confused predicting weather!
---
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40950(at)rv10.net
Guest
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| Posted: Fri Feb 26, 2010 7:40 pm Post subject: vibration in mains on roll out |
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Hmm ... I have some ideas, let me research them. I need to look for some low cost instrumentation to gather data for frequency measurement and load vs. displacement. Maybe there is some low cost stuff out there I'm not aware of others can turn me on to. Then do some calculations to confirm the theory with the actual and decide where to go next. Like I said, might be easy, might be hard. But definitely a fun science experiment.
Tom
do not archive
On Feb 26, 2010, at 8:18 PM, ricksked(at)cox.net wrote:
| Quote: |
Tom,
I will measure you do the math...let me know what you need and maybe we can provide a definitive answer to this problem...we don't need no stinkin computer models...they get confused predicting weather!
|
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bob.kaufmann(at)cox.net
Guest
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| Posted: Fri Feb 26, 2010 8:06 pm Post subject: vibration in mains on roll out |
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My calculations show that a clear spruce stiffener .0375 by 1.75 by 29.75
inch will take all the vibration out.
Bob K
P.S. Shares being offered in the Golden Gate Bridge at only $1.75 per
share.
Do not archive
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Tim Olson
Joined: 25 Jan 2007
Posts: 2881
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| Posted: Fri Feb 26, 2010 8:09 pm Post subject: vibration in mains on roll out |
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That's exactly what it is...a resonance issue. That's why we
all see it at the same speed to whatever degree it happens.
On mine, I can get a walking of the gear at high speed
taxi. Some days it's not there, but if you set off the
right vibration it'll trigger. Then you tap the brakes and
it's gone. On landing, after balancing my tires, it's usually
pretty good or nonexistant. But, before I balanced the tires,
or after they start to wear from things like flat spots (caused
by harsh braking or patchy ice) it can get easier to set off.
If you get anything that causes any up-down or fore-aft
motion, it'll trigger the resonance and it happens only for
maybe 5kts worth of speed range. Some days it doesn't happen
at all. Others, it'll give a good shake. But, it all does
get better with everything balanced. With tapered rod
gear like that, it's definitely going to happen to some people.
The stiffening of the gear may improve it with carbon fiber,
wood, or whatever, but, it may also just change it so that it
happens at some other resonant frequency or speed. With
things balanced I haven't found it to be any sort of major
problem. If maybe you have oddly toe'd or formed gear legs,
or tires, it may be different for you. Scott had bigger
problems with his Goodyear tires than his retreads....but
then again, each tire has a different shape/weight. I just
figure that with the gear legs our babies were born with, it's
going to be a fact of life to some degree. We could try
all sorts of things, and maybe be successful. But, for mine,
with things balanced, it's just not worth doing much to.
Before I balanced the tires, it bugged me a bit sometimes
though. I do think that axle nut tension is a factor too.
Try a little tighter or looser and it may change a bit.
Remember, there are a couple hundred RV-10's flying. Probably
a majority have at least felt a little of what this issue
is, but there are only a small handful of people who really
feel it's a big problem for them. Our planes aren't all
identical, so it's up to the builders to deal with their own
specific issues, and if they share their experiences then maybe
others with the issues can improve theirs too. But, there
are also a large share of RV-10's for which this isn't a big
issue at all. Considering there isn't much that can be done
BEFORE you find if you have a problem, other than a change in
gear leg design, just build the plane, fly it, balance
everything as best you can, and if you decide you need more,
share your ideas and see if it helps. But it's nothing to
worry about if you aren't already flying.
Tim Olson - RV-10 N104CD
Tom Koelzer wrote:
| Quote: | An engineering look at the problem (I got this off the web). My comments below the math:
http://en.wikipedia.org/wiki/Fundamental_frequency
Consider a beam, fixed at one end and having a mass attached to the other, this would be a single degree of freedom (SDoF) oscillator. Once set into motion it will oscillate at its natural frequency. For a single degree of freedom oscillator, a system in which the motion can be described by a single coordinate, the natural frequency depends on two system properties; mass and stiffness. The radian frequency, ?n, can be found using the following equation:
------------------------------------------------------------------------
------------------------------------------------------------------------
Where:
k = stiffness of the beam
m = mass of weight
?n = radian frequency (radians per second)
The stiffness, k, of a body is a measure of the resistance offered by an elastic body to deformation (bending, stretching or compression).
------------------------------------------------------------------------
------------------------------------------------------------------------
where
P is a steady force applied on the body
? is the displacement produced by the force (for instance, the deflection of a beam, or the change in length of a stretched spring)
From the radian frequency, the natural frequency, fn, can be found by simply dividing ?n by 2?. Without first finding the radian frequency, the natural frequency can be found directly using:
------------------------------------------------------------------------
------------------------------------------------------------------------
Where:
fn = natural frequency in hertz (cycles/second)
k = stiffness of the beam (Newtons/Meter or N/m)
m = mass of weight (kg) while doing the modal analysis of structures and mechnical equipments, the frequency of 1st mode is called fundamental frequency.
==================
My thoughts: The landing gear may have a natural frequency around the 40 mph or so speed some have experienced. At that speed, without much energy required to excite the harmonic or resonance response, it doesn't take much to cause a noticeable vibration (out of alignment, out of balance, surface condition, gear loading due to gross weight, etc). The wheel rpm at the offending speed could give us a clue as to the natural frequency. That is frequency = velocity/tire circumference. Then work the rest of the formulas backwards to determine theoretical mass and maybe even do some stiffness measurements on the gear leg. Might get close, might not but the goal here is to get a look at what it would take to move the natural frequency around until it is no longer excited during the takeoff or landing phase while on the ground.
Adding more weight, like a heavier tire, could conceivably lower the natural frequency to the point where the natural damping of the steel gear leg is such that at a lower speed the rotating wheel can no longer excite the harmonic mode. Same goes for stiffening the gear leg with carbon or wood: it may raise the frequency and damping factor such that the mode again cannot be excited at the new condition. Classic spring mass damper solution of sorts.
Perfect alignment, perfect balance, perfectly smooth landings and runways would probably not excite the harmonic on roll-out. But we all know these conditions don't last very long. So the answer is probably some combination of straight gear (aligned), better damping (carbon stiffener or other mod on to the gear leg to either raise the natural frequency, damping or both), and balanced wheels and tires.
Sorry for all the formulas but it helped me think it out out,
Tom
#40950 waiting for long build wings.
Crestview, FL
On Feb 26, 2010, at 5:34 PM, Pascal wrote:
>
>
> I have to think if the step gets to the point that many want to have an access panel to resolve it that the gear may be the same issue. Specifically, the bolt tends to become looser each time someone kicks off the step or the gear absorbs the perfect landings causing it to slowly get more loose.
> Don has a resolution to his by replacing the tires and balancing them, that may be the solution but there may be others, I am watching this issue closely as there are far more complains about the gear than there are about the doors flying off, yet Vans has never heard of this issue before anyone calls them on it. BTW- Scott at Vans support has been straight up with me, he's told me he knows of issues, has always given a suggestion and never told me I was the first to tell him about it, never seems to even cross his mind.. I would encourage some to give Vans a call and see if they have any suggestions, maybe enough calls and they may pursue a solution.
>
> --------------------------------------------------
> From: <ricksked(at)cox.net>
> Sent: Friday, February 26, 2010 11:55 AM
> To: <rv10-list(at)matronics.com>
> Subject: Re: Re: vibration in mains on roll out
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Kelly McMullen
Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ
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| Posted: Fri Feb 26, 2010 8:31 pm Post subject: vibration in mains on roll out |
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I can give you a better deal on ocean beach front property in Aridzona. 
1K per acre.
On Fri, Feb 26, 2010 at 9:05 PM, Bob Kaufmann <bob.kaufmann(at)cox.net> wrote:
| Quote: | P.S. Shares being offered in the Golden Gate Bridge at only $1.75 per
share.
Do not archive
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
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ricksked(at)cox.net
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| Posted: Fri Feb 26, 2010 8:46 pm Post subject: vibration in mains on roll out |
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Whatever The F that means
Sent via BlackBerry by AT&T
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40950(at)rv10.net
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| Posted: Fri Feb 26, 2010 8:51 pm Post subject: vibration in mains on roll out |
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These are great discussions. And thanks, Tim, you have a great insight for what really matter. Flying is what matters, safe flying. This is an nuisance that I find particularly interesting because of my background (aero engr and flight test) and does not threaten safety of the vehicle. But a nuisance none the less.
So generally speaking, I think there may be a resonance mode with the gear that causes problems for some and not for others. The catalyst is what excites the mode and how to dampen it. If not excited, nothing happens (all guys know this). I'm interested in a solution, long term. This is not like doors flying off the airplane. This is like explaining to my mother why my airplane shakes when I land when she rides with me. It's just that simple. No problem, maybe only an embarrassment. I'd like to contribute to a solution for those who see this problem more than others and are interested in doing something about it. Van's might have an idea or two as well (other than wood glued to the landing gear). I'll ask later if we get to that point.
I'll talk to Neal and see what we can come up with regard to cheap instrumentation. I have other ideas to pursue. If there is little interest, that's ok. I believe in supply and demand as the driver to all solutions. If I see this when I finally get to the gear and flying, then I'll tackle the problem again.
Tom aka Cowboy
On Feb 26, 2010, at 10:07 PM, Tim Olson wrote:
| Quote: |
That's exactly what it is...a resonance issue. That's why we
all see it at the same speed to whatever degree it happens.
On mine, I can get a walking of the gear at high speed
taxi. Some days it's not there, but if you set off the
right vibration it'll trigger. Then you tap the brakes and
it's gone. On landing, after balancing my tires, it's usually
pretty good or nonexistant. But, before I balanced the tires,
or after they start to wear from things like flat spots (caused
by harsh braking or patchy ice) it can get easier to set off.
If you get anything that causes any up-down or fore-aft
motion, it'll trigger the resonance and it happens only for
maybe 5kts worth of speed range. Some days it doesn't happen
at all. Others, it'll give a good shake. But, it all does
get better with everything balanced. With tapered rod
gear like that, it's definitely going to happen to some people.
The stiffening of the gear may improve it with carbon fiber,
wood, or whatever, but, it may also just change it so that it
happens at some other resonant frequency or speed. With
things balanced I haven't found it to be any sort of major
problem. If maybe you have oddly toe'd or formed gear legs,
or tires, it may be different for you. Scott had bigger
problems with his Goodyear tires than his retreads....but
then again, each tire has a different shape/weight. I just
figure that with the gear legs our babies were born with, it's
going to be a fact of life to some degree. We could try
all sorts of things, and maybe be successful. But, for mine,
with things balanced, it's just not worth doing much to.
Before I balanced the tires, it bugged me a bit sometimes
though. I do think that axle nut tension is a factor too.
Try a little tighter or looser and it may change a bit.
Remember, there are a couple hundred RV-10's flying. Probably
a majority have at least felt a little of what this issue
is, but there are only a small handful of people who really
feel it's a big problem for them. Our planes aren't all
identical, so it's up to the builders to deal with their own
specific issues, and if they share their experiences then maybe
others with the issues can improve theirs too. But, there
are also a large share of RV-10's for which this isn't a big
issue at all. Considering there isn't much that can be done
BEFORE you find if you have a problem, other than a change in
gear leg design, just build the plane, fly it, balance
everything as best you can, and if you decide you need more,
share your ideas and see if it helps. But it's nothing to
worry about if you aren't already flying.
Tim Olson - RV-10 N104CD
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No, I have no understanding, as I haven't experienced it. Kelly mentioned the physics of why something heavy would dampen it and that's what I addressed. I believe my comment in that context was accurate. HA! 
...Tim do you still have this issue and just living with it?