Today's Message Index:
----------------------
1. 06:46 AM - Re: Re: Landing gear shimmy (Gerd + Uli Nowack)
2. 07:23 AM - Re: Re: Landing gear shimmy (Nick Otterback)
3. 07:26 AM - Re: Re: Landing gear shimmy (luigi di napoli)
4. 07:55 AM - Re: Re: Landing gear shimmy (Gerd + Uli Nowack)
5. 11:22 AM - Re: Re: Landing gear shimmy (luigi di napoli)
Message 1
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| Subject: | Re: Landing gear shimmy |
I think some time ago somebody mentioned that round gear legs are prone
to shimmy.
IMHO the trouble results from the spring properties of the round gear
legs and a certain toe in.
You can see on the video that the gear legs do a fast fore and aft
motion . If one looks at the gear geometry one sees that
a bending aft will also mean a decrease in toe in ( or increase in toe
out, whatever) This will momentarily increase the gear drag and result
a circular motion of the wheel and the gear leg.
The solution: make machined airfoil- shaped gear legs ( made from
Aluminum, no expensive and difficult to machine Titan necessary!) that
don`t bend fore and aft but still can do their bending outward for the
necessary suspension. They could have a groove for the brake line on
the inside, so we would`t even need leg fairings!
Just my 3 Euro-Cents!
Gerd D-ELIY No. 89
Am 10.05.2012 03:45, schrieb Craig Sumner:
> --> Lightning-List message posted by: "Craig Sumner"<craigsumner@comcast.net>
>
> Outstanding video Bill! Thanks for taking the time to mount a camera for
> all to see. I will share this with others and see what our NASA/DoD
> engineers think could be the right fix. I know the folks in Shelbyville
> (who are outstanding folks) would like to see this issue resolved.
> Best Regards,
> Craig Sumner
> N155JM
> Esqual 074
>
> -----Original Message-----
> From: owner-lightning-list-server@matronics.com
> [mailto:owner-lightning-list-server@matronics.com] On Behalf Of Bill Strahan
> Sent: Tuesday, May 08, 2012 4:37 PM
> To: lightning-list@matronics.com
> Subject: Lightning-List: Re: Landing gear shimmy
>
> --> Lightning-List message posted by: "Bill Strahan"<bill@gdsx.com>
>
> Okay, no egg on my face I suppose. Finally got a video camera to check
> things out. It's clearly the main gear.
>
> It should be on youtube here: http://youtu.be/rzb_eeyhLJU in a few
> minutes.
>
> This clip makes it pretty visible starting at 0:28 on the landing roll. I
> don't use the brakes much to try to discount that influence, and I let the
> nose drop the moment I land so I can see if it's the nose or mains.
>
> On taxiing back, I decided to accelerate and test it again, and the second
> shimmy can be seen at 1:28.
>
> It may not look like much on a video camera, but that's a serious bit of
> wiggling in the cockpit.
>
> I'm astounded that the stiffeners don't make an impact on it. I can't flex
> them by hand at all in that direction.
>
> This is a big deal for me because I fly into some pretty busy places and it
> occurs right at the speed I'd be doing on a long runway to hurry up and make
> a turnoff. That, and I don't like passengers looking a little freaked out
> and asking what the heck that was. And it can't be good for the whole plane
> to violently shake like that.
>
> For the record, I've balanced tires, changed to 6 ply tires, balanced those,
> and now the fiberglass stiffeners. No relief yet. Not sure what comes
> next.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=372654#372654
>
>
Message 2
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| Subject: | Re: Landing gear shimmy |
Gerd,
Its funny you mention the airfoil shape. I discussed it yesterday with our
machine shop and they are getting prices on both.
Nick
-----Original Message-----
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Gerd + Uli
Nowack
Sent: Thursday, May 10, 2012 8:46 AM
Subject: Re: Lightning-List: Re: Landing gear shimmy
--> <NowackLinden@gmx.de>
I think some time ago somebody mentioned that round gear legs are prone to
shimmy.
IMHO the trouble results from the spring properties of the round gear legs
and a certain toe in.
You can see on the video that the gear legs do a fast fore and aft motion .
If one looks at the gear geometry one sees that a bending aft will also
mean a decrease in toe in ( or increase in toe out, whatever) This will
momentarily increase the gear drag and result a circular motion of the wheel
and the gear leg.
The solution: make machined airfoil- shaped gear legs ( made from
Aluminum, no expensive and difficult to machine Titan necessary!) that don`t
bend fore and aft but still can do their bending outward for the necessary
suspension. They could have a groove for the brake line on the inside, so
we would`t even need leg fairings!
Just my 3 Euro-Cents!
Gerd D-ELIY No. 89
Am 10.05.2012 03:45, schrieb Craig Sumner:
> --> Lightning-List message posted by: "Craig
> --> Sumner"<craigsumner@comcast.net>
>
> Outstanding video Bill! Thanks for taking the time to mount a camera
> for all to see. I will share this with others and see what our
> NASA/DoD engineers think could be the right fix. I know the folks in
> Shelbyville (who are outstanding folks) would like to see this issue
resolved.
> Best Regards,
> Craig Sumner
> N155JM
> Esqual 074
>
> -----Original Message-----
> From: owner-lightning-list-server@matronics.com
> [mailto:owner-lightning-list-server@matronics.com] On Behalf Of Bill
> Strahan
> Sent: Tuesday, May 08, 2012 4:37 PM
> To: lightning-list@matronics.com
> Subject: Lightning-List: Re: Landing gear shimmy
>
> --> Lightning-List message posted by: "Bill Strahan"<bill@gdsx.com>
>
> Okay, no egg on my face I suppose. Finally got a video camera to
> check things out. It's clearly the main gear.
>
> It should be on youtube here: http://youtu.be/rzb_eeyhLJU in a few
> minutes.
>
> This clip makes it pretty visible starting at 0:28 on the landing
> roll. I don't use the brakes much to try to discount that influence,
> and I let the nose drop the moment I land so I can see if it's the nose or
mains.
>
> On taxiing back, I decided to accelerate and test it again, and the
> second shimmy can be seen at 1:28.
>
> It may not look like much on a video camera, but that's a serious bit
> of wiggling in the cockpit.
>
> I'm astounded that the stiffeners don't make an impact on it. I can't
> flex them by hand at all in that direction.
>
> This is a big deal for me because I fly into some pretty busy places
> and it occurs right at the speed I'd be doing on a long runway to
> hurry up and make a turnoff. That, and I don't like passengers
> looking a little freaked out and asking what the heck that was. And
> it can't be good for the whole plane to violently shake like that.
>
> For the record, I've balanced tires, changed to 6 ply tires, balanced
> those, and now the fiberglass stiffeners. No relief yet. Not sure
> what comes next.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=372654#372654
>
>
Message 3
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| Subject: | Re: Landing gear shimmy |
Tha gear legs of Pioneer 200/300 are made exactly how described from Gerd.
=0AMore than one third of the leg, from the wheel axle, is "sliced" from bo
th side.-=0AProbably the reason is the one anounced.=0AIf I find a pictur
e of this leg, I-will provide to show one.=0ARegards=0ALuigi=0AEsqual I-9
854=0A-=0A=0A=0A________________________________=0A Da: Gerd + Uli Nowack
<NowackLinden@gmx.de>=0AA: lightning-list@matronics.com =0AInviato: Gioved
=EC 10 Maggio 2012 15:46=0AOggetto: Re: Lightning-List: Re: Landing gear sh
inden@gmx.de>=0A=0AI think some time ago somebody mentioned that round gear
legs are prone =0Ato shimmy.=0AIMHO the trouble results from the spring pr
operties of the round gear =0Alegs and a certain toe in.=0AYou can see on t
he video that the gear legs do a- fast fore and aft =0Amotion . If one lo
oks at the gear geometry one sees that=0Aa bending- aft will also mean a
decrease in toe in ( or increase in toe =0Aout, whatever) This will momenta
rily increase the gear drag and result- =0Aa circular motion of the wheel
and the gear leg.=0A- The solution: make machined airfoil- shaped gear l
egs ( made from =0AAluminum, no expensive and difficult to machine Titan ne
cessary!) that =0Adon`t bend fore and aft but still can do their bending ou
tward for the =0Anecessary suspension.- They could- have a groove for t
he brake line on =0Athe inside, so we would`t even need leg fairings!=0AJus
t my 3 Euro-Cents!=0A=0AGerd- D-ELIY- - No. 89=0A=0A=0A=0A=0AAm 10.05
.2012 03:45, schrieb Craig Sumner:=0A> -->- Lightning-List message posted
by: "Craig Sumner"<craigsumner@comcast.net>=0A>=0A> Outstanding video Bill
!- Thanks for taking the time to mount a camera for=0A> all to see.- I
will share this with others and see what our NASA/DoD=0A> engineers think c
ould be the right fix.- I know the folks in Shelbyville=0A> (who are outs
tanding folks) would like to see this issue resolved.=0A> Best Regards,=0A>
Craig Sumner=0A> N155JM=0A> Esqual 074=0A>=0A> -----Original Message-----
=0A> From: owner-lightning-list-server@matronics.com=0A> [mailto:owner-ligh
tning-list-server@matronics.com] On Behalf Of Bill Strahan=0A> Sent: Tuesda
y, May 08, 2012 4:37 PM=0A> To: lightning-list@matronics.com=0A> Subject: L
ightning-List: Re: Landing gear shimmy=0A>=0A> -->- Lightning-List messag
e posted by: "Bill Strahan"<bill@gdsx.com>=0A>=0A> Okay, no egg on my face
I suppose.- Finally got a video camera to check=0A> things out.- It's c
learly the main gear.=0A>=0A> It should be on youtube here:- http://youtu
.be/rzb_eeyhLJU- in a few=0A> minutes.=0A>=0A> This clip makes it pretty
visible starting at 0:28 on the landing roll.- I=0A> don't use the brakes
much to try to discount that influence, and I let the=0A> nose drop the mo
ment I land so I can see if it's the nose or mains.=0A>=0A> On taxiing back
, I decided to accelerate and test it again, and the second=0A> shimmy can
be seen at 1:28.=0A>=0A> It may not look like much on a video camera, but t
hat's a serious bit of=0A> wiggling in the cockpit.=0A>=0A> I'm astounded t
hat the stiffeners don't make an impact on it.- I can't flex=0A> them by
hand at all in that direction.=0A>=0A> This is a big deal for me because I
fly into some pretty busy places and it=0A> occurs right at the speed I'd b
e doing on a long runway to hurry up and make=0A> a turnoff.- That, and I
don't like passengers looking a little freaked out=0A> and asking what the
heck that was.- And it can't be good for the whole plane=0A> to violentl
y shake like that.=0A>=0A> For the record, I've balanced tires, changed to
6 ply tires, balanced those,=0A> and now the fiberglass stiffeners.- No r
elief yet.- Not sure what comes=0A> next.=0A>=0A>=0A>=0A>=0A> Read this t
opic online here:=0A>=0A> http://forums.matronics.com/viewtopic.php?p=372
654#372654=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A
=================
Message 4
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| Subject: | Re: Landing gear shimmy |
Nick,
If you ve got the price please tell us!
I think I might pick up a pair of short ones in October!
Gerd
Am 10.05.2012 16:22, schrieb Nick Otterback:
> --> Lightning-List message posted by: "Nick Otterback"<nick@flylightning.net>
>
> Gerd,
>
> Its funny you mention the airfoil shape. I discussed it yesterday with our
> machine shop and they are getting prices on both.
>
> Nick
>
> -----Original Message-----
> From: owner-lightning-list-server@matronics.com
> [mailto:owner-lightning-list-server@matronics.com] On Behalf Of Gerd + Uli
> Nowack
> Sent: Thursday, May 10, 2012 8:46 AM
> To: lightning-list@matronics.com
> Subject: Re: Lightning-List: Re: Landing gear shimmy
>
> --> Lightning-List message posted by: Gerd + Uli Nowack
> --> <NowackLinden@gmx.de>
>
> I think some time ago somebody mentioned that round gear legs are prone to
> shimmy.
> IMHO the trouble results from the spring properties of the round gear legs
> and a certain toe in.
> You can see on the video that the gear legs do a fast fore and aft motion .
> If one looks at the gear geometry one sees that a bending aft will also
> mean a decrease in toe in ( or increase in toe out, whatever) This will
> momentarily increase the gear drag and result a circular motion of the wheel
> and the gear leg.
> The solution: make machined airfoil- shaped gear legs ( made from
> Aluminum, no expensive and difficult to machine Titan necessary!) that don`t
> bend fore and aft but still can do their bending outward for the necessary
> suspension. They could have a groove for the brake line on the inside, so
> we would`t even need leg fairings!
> Just my 3 Euro-Cents!
>
> Gerd D-ELIY No. 89
>
>
> Am 10.05.2012 03:45, schrieb Craig Sumner:
>> --> Lightning-List message posted by: "Craig
>> --> Sumner"<craigsumner@comcast.net>
>>
>> Outstanding video Bill! Thanks for taking the time to mount a camera
>> for all to see. I will share this with others and see what our
>> NASA/DoD engineers think could be the right fix. I know the folks in
>> Shelbyville (who are outstanding folks) would like to see this issue
> resolved.
>> Best Regards,
>> Craig Sumner
>> N155JM
>> Esqual 074
>>
>> -----Original Message-----
>> From: owner-lightning-list-server@matronics.com
>> [mailto:owner-lightning-list-server@matronics.com] On Behalf Of Bill
>> Strahan
>> Sent: Tuesday, May 08, 2012 4:37 PM
>> To: lightning-list@matronics.com
>> Subject: Lightning-List: Re: Landing gear shimmy
>>
>> --> Lightning-List message posted by: "Bill Strahan"<bill@gdsx.com>
>>
>> Okay, no egg on my face I suppose. Finally got a video camera to
>> check things out. It's clearly the main gear.
>>
>> It should be on youtube here: http://youtu.be/rzb_eeyhLJU in a few
>> minutes.
>>
>> This clip makes it pretty visible starting at 0:28 on the landing
>> roll. I don't use the brakes much to try to discount that influence,
>> and I let the nose drop the moment I land so I can see if it's the nose or
> mains.
>> On taxiing back, I decided to accelerate and test it again, and the
>> second shimmy can be seen at 1:28.
>>
>> It may not look like much on a video camera, but that's a serious bit
>> of wiggling in the cockpit.
>>
>> I'm astounded that the stiffeners don't make an impact on it. I can't
>> flex them by hand at all in that direction.
>>
>> This is a big deal for me because I fly into some pretty busy places
>> and it occurs right at the speed I'd be doing on a long runway to
>> hurry up and make a turnoff. That, and I don't like passengers
>> looking a little freaked out and asking what the heck that was. And
>> it can't be good for the whole plane to violently shake like that.
>>
>> For the record, I've balanced tires, changed to 6 ply tires, balanced
>> those, and now the fiberglass stiffeners. No relief yet. Not sure
>> what comes next.
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=372654#372654
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
Message 5
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| Subject: | Re: Landing gear shimmy |
Here some pictures .=0AThe tapering starts from the arrow on the tape .=0Ar
egards=0ALuigi=0A=0A=0A=0A________________________________=0A Da: Nick Otte
rback <nick@flylightning.net>=0AA: lightning-list@matronics.com =0AInviato:
Gioved=EC 10 Maggio 2012 16:22=0AOggetto: RE: Lightning-List: Re: Landing
ick@flylightning.net>=0A=0AGerd,=0A=0AIts funny you mention the airfoil sha
pe. I discussed it yesterday with our=0Amachine shop and they are getting p
rices on both. =0A=0ANick
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