Today's Message Index:
----------------------
1. 06:36 AM - Re: Re: Landing gear shimmy (Bernard Melendez, Jr.)
2. 08:14 AM - Re: Landing gear shimmy (Jaythree)
3. 08:24 AM - Re: Re: Landing gear shimmy (James, Clive R)
4. 10:03 PM - Re: Landing gear shimmy (Jaythree)
Message 1
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| Subject: | Re: Landing gear shimmy |
The old Cessna 150 I used to fly as a student also had nose wheel shimmy. I
t even had a gas strut to help solve that issue, with little help. So, what
's new?
Bernardo
--- On Sat, 6/2/12, Jaythree <donaldberk@hotmail.com> wrote:
From: Jaythree <donaldberk@hotmail.com>
Subject: Lightning-List: Re: Landing gear shimmy
This forum is a gold mine! I'll start by confessing that with only six hour
s and twelve landings on my new Esqual (with Lightning upgrades) I managed
to bend the nosegear leg on a soft turf runway. I bought the Esqual from th
e builder, who did a magnificent job and I feel worse about dinging his cra
ftsmanship than anything else right now.
But to the point...shimmy. I did experience it on all landings at 35-45 mph
rollout. Although the consensus on this forum is that mains gearlegs and/o
r alignment seem to be the gremlin, I'm wondering if a significant factor m
ay b the angled nosegear trailing fork. Angling the fork aft-down creates a
geometry in which the weight on the swivel wants to rotate the forks forwa
rd. It's like a ball on a ramp. I have never seen castoring trailing fork n
osegear where the fork was not parallel to the ground, eg., Grumman. I don'
t understand the purpose of the unstable geometry on the Esqual/Lightning.
At 35-45 mph, the balancing forces of weight, fairing weathervaning and fly
wheel momentum of the nosewheel would tend to create a perfect scenario for
shimmy. Shimmy up front of course would translate to the mains. Any commen
ts, positive or negative, appreciated.
Bill Strahan wrote:
> Hey, I've talked about this before, haven't I?- I've had 3 big changes
I wanted to make for a long time:- 1)- Fix fuel distribution issue.-
2)- Make some short wingtips.- 3)- Eliminate the landing gear shimmy.
>
> I installed the flow straightener tube and vanes that Nick sent me about
a year ago.- That did an amazing job.- Perfect?- No.- Good enough t
hat I'm not considering installing fuel injection?- Yep.- So #1 is adre
ssed.
>
> I still need to make short wingtips, but my passenger yesterday asked "Wh
y does it shake like that after you land?"---GRRRRR.
>
> So I bought an axe handle and started chatting with neighbors here on the
airport about cutting and shaping it.- I figured I'd buy a 1.125" ball c
utter and put a radius in it.- Kept putting that off because it didn't so
und like fun.
>
> Then it hit me:- I really just need it stiffer in fore/aft flexing.-
And whatever stiffener I make needs to glue to the gear leg so it needs to
be a very good fit.- Nothing fits better than fiberglass built in-place!
>
> I decided I would tape off the gear and lay up 3 laminations of 7oz cloth
directly onto the back of the gear leg.- I did that tonight, and it's cu
ring.- Tomorrow I'll sand the back of that and use some flock and 5 minut
e epoxy to attach a 1/8" thick piece of balsa wood that extends about 1.5"
behind the gear.- Once that's cured I'll lay up about 6 layers of cloth o
n both sides of the balsa, overlapping onto the section that's on the gear.
- So the gear shouldn't end up much stiffer since it only has 1/8" thickn
ess between the 6 layer lamination, but it should be SUPER stiff across the
1.5" section.
>
> So I should get that done tomorrow, and let it cure overnight.- Then I'
ll pop it off the gear, trim it, and glue it onto the landing gear leg.
>
> Any thoughts?- Nick, any suggestions on the best adhesive to attach to
the gear?- Should I remove the paint or glue to the paint?
>
> When I glue it I'll put a couple of zip ties around it to hold it while i
t cures, and leave them on just in case it ever comes loose.
>
> Fingers crossed, I can report in a few days that I have eliminated the da
ng shimmy once and for all.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=374512#374512
le, List Admin.
Message 2
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| Subject: | Re: Landing gear shimmy |
Well, the geometry and physics can be different for every shimmy, which is a mass
oscillation. . I was just talking about theEsqual/Lightning.
[quote="n45bm(at)yahoo.com"]The old Cessna 150 I used to fly as a student also
had nose wheel shimmy. It even had a gas strut to help solve that issue, with
little help. So, what's new?
Bernardo
--- On Sat, 6/2/12, Jaythree wrote:
>
> From: Jaythree
> Subject: Re: Landing gear shimmy
> To: lightning-list@matronics.com
> Date: Saturday, June 2, 2012, 12:13 AM
>
>
> This forum is a gold mine! I'll start by confessing that with only six hours
and twelve landings on my new Esqual (with Lightning upgrades) I managed to bend
the nosegear leg on a soft turf runway. I bought the Esqual from the builder,
who did a magnificent job and I feel worse about dinging his craftsmanship
than anything else right now.
>
> But to the point...shimmy. I did experience it on all landings at 35-45 mph rollout.
Although the consensus on this forum is that mains gearlegs and/or alignment
seem to be the gremlin, I'm wondering if a significant factor may b the
angled nosegear trailing fork. Angling the fork aft-down creates a geometry in
which the weight on the swivel wants to rotate the forks forward. It's like
a ball on a ramp. I have never seen castoring trailing fork nosegear where the
fork was not parallel to the ground, eg., Grumman. I don't understand the purpose
of the unstable geometry on the Esqual/Lightning. At 35-45 mph, the balancing
forces of weight, fairing weathervaning and flywheel momentum of the nosewheel
would tend to create a perfect scenario for shimmy. Shimmy up front of
course would translate to the mains. Any comments, positive or negative, appreciated.
>
>
> Bill Strahan wrote:
>
> > Hey, I've talked about this before, haven't I? I've had 3 big changes I wanted
to make for a long time: 1) Fix fuel distribution issue. 2) Make some
short wingtips. 3) Eliminate the landing gear shimmy.
> >
> > I installed the flow straightener tube and vanes that Nick sent me about a
year ago. That did an amazing job. Perfect? No. Good enough that I'm not
considering installing fuel injection? Yep. So #1 is adressed.
> >
> > I still need to make short wingtips, but my passenger yesterday asked "Why
does it shake like that after you land?" GRRRRR.
> >
> > So I bought an axe handle and started chatting with neighbors here on the
airport about cutting and shaping it. I figured I'd buy a 1.125" ball cutter
and put a radius in it. Kept putting that off because it didn't sound like fun.
> >
> > Then it hit me: I really just need it stiffer in fore/aft flexing. And whatever
stiffener I make needs to glue to the gear leg so it needs to be a very
good fit. Nothing fits better than fiberglass built in-place!
> >
> > I decided I would tape off the gear and lay up 3 laminations of 7oz cloth
directly onto the back of the gear leg. I did that tonight, and it's curing.
Tomorrow I'll sand the back of that and use some flock and 5 minute epoxy to
attach a 1/8" thick piece of balsa wood that extends about 1.5" behind the gear.
Once that's cured I'll lay up about 6 layers of cloth on both sides of the
balsa, overlapping onto the section that's on the gear. So the gear shouldn't
end up much stiffer since it only has 1/8" thickness between the 6 layer lamination,
but it should be SUPER stiff across the 1.5" section.
> >
> > So I should get that done tomorrow, and let it cure overnight. Then I'll
pop it off the gear, trim it, and glue it onto the landing gear leg.
> >
> > Any thoughts? Nick, any suggestions on the best adhesive to attach to the
gear? Should I remove the paint or glue to the paint?
> >
> > When I glue it I'll put a couple of zip ties around it to hold it while it
cures, and leave them on just in case it ever comes loose.
> >
> > Fingers crossed, I can report in a few days that I have eliminated the dang
shimmy once and for all.
> >
> >
>
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtosp; --> http://www.matronics.com/Navigator?Lightning-Lis --> http://www.matronics.c==================
>
>
>
>
>
> [b]
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=374535#374535
Message 3
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| Subject: | Re: Landing gear shimmy |
I had the angled leg on the Esqual for the first 30 hours, no shimmy but
did make the steering a little twitchy. I have the lightning one on now
thankfully.
Pulling the plane around the hangar it was off like a supermarket
trolley.
Regarding the shimmy, does it promote tyre wear?
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Bernard
Melendez, Jr.
Sent: 02 June 2012 14:36
Subject: Re: Lightning-List: Re: Landing gear shimmy
The old Cessna 150 I used to fly as a student also had nose wheel
shimmy. It even had a gas strut to help solve that issue, with little
help. So, what's new?
Bernardo
--- On Sat, 6/2/12, Jaythree <donaldberk@hotmail.com> wrote:
From: Jaythree <donaldberk@hotmail.com>
Subject: Lightning-List: Re: Landing gear shimmy
<donaldberk@hotmail.com>
This forum is a gold mine! I'll start by confessing that with only six
hours and twelve landings on my new Esqual (with Lightning upgrades) I
managed to bend the nosegear leg on a soft turf runway. I bought the
Esqual from the builder, who did a magnificent job and I feel worse
about dinging his craftsmanship than anything else right now.
But to the point...shimmy. I did experience it on all landings at 35-45
mph rollout. Although the consensus on this forum is that mains gearlegs
and/or alignment seem to be the gremlin, I'm wondering if a significant
factor may b the angled nosegear trailing fork. Angling the fork
aft-down creates a geometry in which the weight on the swivel wants to
rotate the forks forward. It's like a ball on a ramp. I have never seen
castoring trailing fork nosegear where the fork was not parallel to the
ground, eg., Grumman. I don't understand the purpose of the unstable
geometry on the Esqual/Lightning. At 35-45 mph, the balancing forces of
weight, fairing weathervaning and flywheel momentum of the nosewheel
would tend to create a perfect scenario for shimmy. Shimmy up front of
course would translate to the mains. Any comments, positive or negative,
appreciated.
Bill Strahan wrote:
> Hey, I've talked about this before, haven't I? I've had 3 big changes
I wanted to make for a long time: 1) Fix fuel distribution issue. 2)
Make some short wingtips. 3) Eliminate the landing gear shimmy.
>
> I installed the flow straightener tube and vanes that Nick sent me
about a year ago. That did an amazing job. Perfect? No. Good enough
that I'm not considering installing fuel injection? Yep. So #1 is
adressed.
>
> I still need to make short wingtips, but my passenger yesterday asked
"Why does it shake like that after you land?" GRRRRR.
>
> So I bought an axe handle and started chatting with neighbors here on
the airport about cutting and shaping it. I figured I'd buy a 1.125"
ball cutter and put a radius in it. Kept putting that off because it
didn't sound like fun.
>
> Then it hit me: I really just need it stiffer in fore/aft flexing.
And whatever stiffener I make needs to glue to the gear leg so it needs
to be a very good fit. Nothing fits better than fiberglass built
in-place!
>
> I decided I would tape off the gear and lay up 3 laminations of 7oz
cloth directly onto the back of the gear leg. I did that tonight, and
it's curing. Tomorrow I'll sand the back of that and use some flock and
5 minute epoxy to attach a 1/8" thick piece of balsa wood that extends
about 1.5" behind the gear. Once that's cured I'll lay up about 6
layers of cloth on both sides of the balsa, overlapping onto the section
that's on the gear. So the gear shouldn't end up much stiffer since it
only has 1/8" thickness between the 6 layer lamination, but it should be
SUPER stiff across the 1.5" section.
>
> So I should get that done tomorrow, and let it cure overnight. Then
I'll pop it off the gear, trim it, and glue it onto the landing gear
leg.
>
> Any thoughts? Nick, any suggestions on the best adhesive to attach to
the gear? Should I remove the paint or glue to the paint?
>
> When I glue it I'll put a couple of zip ties around it to hold it
while it cures, and leave them on just in case it ever comes loose.
>
> Fingers crossed, I can report in a few days that I have eliminated the
dang shimmy once and for all.
Read this topic online here:
http://forums.matronics.com/viewtosp; -->
<http://forums.matronics.com/viewtopic.php?p=374512#374512>
http://www.matronics.com/Navigator?Lightning-Lis -->
<http://www.matronics.com/Navigator?Lightning-List>
http://www.matronics.c=================
=
<http://forums.matronics.com>
Message 4
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| Subject: | Re: Landing gear shimmy |
Well, the geometry and physics can be different for every shimmy, which is a mass
oscillation. . I was just talking about theEsqual/Lightning.
[quote="n45bm(at)yahoo.com"]The old Cessna 150 I used to fly as a student also
had nose wheel shimmy. It even had a gas strut to help solve that issue, with
little help. So, what's new?
Bernardo
--- On Sat, 6/2/12, Jaythree wrote:
>
> From: Jaythree
> Subject: Re: Landing gear shimmy
> To: lightning-list@matronics.com
> Date: Saturday, June 2, 2012, 12:13 AM
>
>
> This forum is a gold mine! I'll start by confessing that with only six hours
and twelve landings on my new Esqual (with Lightning upgrades) I managed to bend
the nosegear leg on a soft turf runway. I bought the Esqual from the builder,
who did a magnificent job and I feel worse about dinging his craftsmanship
than anything else right now.
>
> But to the point...shimmy. I did experience it on all landings at 35-45 mph rollout.
Although the consensus on this forum is that mains gearlegs and/or alignment
seem to be the gremlin, I'm wondering if a significant factor may b the
angled nosegear trailing fork. Angling the fork aft-down creates a geometry in
which the weight on the swivel wants to rotate the forks forward. It's like
a ball on a ramp. I have never seen castoring trailing fork nosegear where the
fork was not parallel to the ground, eg., Grumman. I don't understand the purpose
of the unstable geometry on the Esqual/Lightning. At 35-45 mph, the balancing
forces of weight, fairing weathervaning and flywheel momentum of the nosewheel
would tend to create a perfect scenario for shimmy. Shimmy up front of
course would translate to the mains. Any comments, positive or negative, appreciated.
>
>
> Bill Strahan wrote:
>
> > Hey, I've talked about this before, haven't I? I've had 3 big changes I wanted
to make for a long time: 1) Fix fuel distribution issue. 2) Make some
short wingtips. 3) Eliminate the landing gear shimmy.
> >
> > I installed the flow straightener tube and vanes that Nick sent me about a
year ago. That did an amazing job. Perfect? No. Good enough that I'm not
considering installing fuel injection? Yep. So #1 is adressed.
> >
> > I still need to make short wingtips, but my passenger yesterday asked "Why
does it shake like that after you land?" GRRRRR.
> >
> > So I bought an axe handle and started chatting with neighbors here on the
airport about cutting and shaping it. I figured I'd buy a 1.125" ball cutter
and put a radius in it. Kept putting that off because it didn't sound like fun.
> >
> > Then it hit me: I really just need it stiffer in fore/aft flexing. And whatever
stiffener I make needs to glue to the gear leg so it needs to be a very
good fit. Nothing fits better than fiberglass built in-place!
> >
> > I decided I would tape off the gear and lay up 3 laminations of 7oz cloth
directly onto the back of the gear leg. I did that tonight, and it's curing.
Tomorrow I'll sand the back of that and use some flock and 5 minute epoxy to
attach a 1/8" thick piece of balsa wood that extends about 1.5" behind the gear.
Once that's cured I'll lay up about 6 layers of cloth on both sides of the
balsa, overlapping onto the section that's on the gear. So the gear shouldn't
end up much stiffer since it only has 1/8" thickness between the 6 layer lamination,
but it should be SUPER stiff across the 1.5" section.
> >
> > So I should get that done tomorrow, and let it cure overnight. Then I'll
pop it off the gear, trim it, and glue it onto the landing gear leg.
> >
> > Any thoughts? Nick, any suggestions on the best adhesive to attach to the
gear? Should I remove the paint or glue to the paint?
> >
> > When I glue it I'll put a couple of zip ties around it to hold it while it
cures, and leave them on just in case it ever comes loose.
> >
> > Fingers crossed, I can report in a few days that I have eliminated the dang
shimmy once and for all.
> >
> >
>
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtosp; --> http://www.matronics.com/Navigator?Lightning-Lis --> http://www.matronics.c==================
>
>
>
>
>
> [b]
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=374567#374567
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