Today's Message Index:
----------------------
1. 03:52 AM - Re: Shimmy update (Dennis Borchardt)
2. 04:15 AM - Re: Shimmy update (Gerd Nowack)
3. 06:02 AM - Section 7; Seat Belt installation is now updated and Available (Nick Otterback)
4. 12:24 PM - Re: Shimmy update (Bernard Melendez, Jr.)
5. 01:33 PM - Re: Shimmy update (James, Clive R)
Message 1
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Bernard
All of the lightning kits we have built including both of my own Lightnings
we have set with toe out with good results. Not perfect but pretty close.
In the build manual "Setting Main Gear Toe" STEP 8, instead of subtracting
2.25" from each side add 2.00" to each side. My 2 cents worth.
Regards
Dennis Borchardt
LIGHTNING AIRCRAFT AUSTRALIA
<mailto:lightningaustralia@bigpond.com> lightningaustralia@bigpond.com
www.lightningaircraft.com.au
Ph 0408 813501
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Bernard
Melendez, Jr.
Sent: Tuesday, 11 September 2012 1:16 PM
Subject: Re: Lightning-List: Shimmy update
Bill,
Standard practice is for toe IN, not toe out. I put 1 1/2 degrees toe in on
my plane, but I've yet to test it as I'm not flying yet. The build manual
says 1 degree toe in, but I added another 1/2 degree, I hope it helps. Leaf
spring gears have less problems with shimmy. I believe that the problem with
round landing gears is that they are more likely to twist with side loads
and once that starts, oh well....
I propose that to help the gear resist twisting motion, shaped wood blocks
be well bonded to the front and rear of the gear and shaped to an airfoil
shape, followed by several plies of fiberglass or carbon fiber. Milling the
roundness to match the tapered gear is the trick. That's the hard part.
If my landing gear exhibits shimmy, that's what I plan to do. The main
objective would be to stiffen the gear to prevent twisting loads. All this
is just speculation on my part, but I can't think of a better way to do it.
Bernardo
Okay, perhaps I'm doing things in a weird order, but I'm still playing with
shimmy stuff. The stiffeners I made from fiberglass didn't help. I'll
remove them soon. I switched to the 6-ply tires, no dice.
I was running the 6-ply tires at just below the max pressure rating of
50PSI. I read about people getting better results with low pressure, so I
dropped it to 26. Holy cow! That made it a TON worse! Weird.
So tonight I hopped out to the hanger and did a quick measurement with a
laser level. Held it on the brake disks and measured six feet in front and
behind the axle, marked it, and calculated toe...came out to 1/2 degree
toe-out.
I've read so much about this, but so much is conflicting. So now my
question is has anyone solved their shimmy by going from toe-out to toe-in?
It sure seems toe-in would work much better, but then I've read people
claiming the exact opposite.
Assuming I decide to go with toe-in, what's the best way to reset? Drill a
new hole and put in a new bolt, or drill the existing hole to the next size
bolt?
Oh, last thing. I didn't verify that each wheel has 1/2 degree toe out. I
just measured the difference between laser lines front and back, and it
works out to a total of 1 degree. For all I know, one is set differently
from the other, but I'll verify that and adjust accordingly if I reset to
toe-in.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=382840#382=====================
Archive Search <http://forums.matronics.com/viewtopic.php?p=382840#382840>
Message 2
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| Subject: | Re: Shimmy update |
Bernardo,
I agree with your opinion, that the round gear legs are causing the trouble , and
I like your plan to modify them.
1st:Have you started to make your gear legs or are you still planning.?
2nd: have you (or anyone else!)considered to use model builder`s foam instead of
wood? The wood might have more "springiness", but one could make up for that
with just more (unidirectional) epoxy-glass, maybe even carbon rovings. Andfoam
is much easier to shape!
3rd: to save weight it might be a nice idea to sand or mill aluminum from the side
off the gear legs first, maybe a 1/4 ", total , or .4 "( 1cm)-of course the
ends have to remain round to fit their receiving tubes.
Has anybody experience with such a combined aluminum / epoxy- spring?
Well, that is roughly what I have in mind if the shimmy starts shaking my baby.
During the next days I will bolt the wheel pants on , and then I will see what
happens.
Btw that will be the time when I can publish a few performance data.
And pictures as my contribution for the Lightning Of The Year-contest ;-)
Gerd D-ELIY , kit 89
-------- Original-Nachricht --------
> Datum: Mon, 10 Sep 2012 20:45:51 -0700 (PDT)
> Von: "Bernard Melendez, Jr." <n45bm@yahoo.com>
> An: lightning-list@matronics.com
> Betreff: Re: Lightning-List: Shimmy update
> Bill,
> Standard practice is for toe IN, not toe out. I put 1 1/2 degrees toe in
> on my plane, but I've yet to test it as I'm not flying yet. The build manual
> says 1 degree toe in, but I added another 1/2 degree, I hope it helps.
> Leaf spring gears have less problems with shimmy. I believe that the problem
> with round landing gears is that they are more likely to twist with side
> loads and once that starts, oh well....
> I propose that to help the gear resist twisting motion, shaped wood blocks
> be well bonded to the front and rear of the gear and shaped to an airfoil
> shape, followed by several plies of fiberglass or carbon fiber. Milling the
> roundness to match the tapered gear is the trick. That's the hard part.
> If my landing gear exhibits shimmy, that's what I plan to do. The main
> objective would be to stiffen the gear to prevent twisting loads. All this is
> just speculation on my part, but I can't think of a better way to do it.
> Bernardo
>
> Okay, perhaps I'm doing things in a weird order, but I'm still playing
> with shimmy stuff. The stiffeners I made from fiberglass didn't help. I'll
> remove them soon. I switched to the 6-ply tires, no dice.
>
> I was running the 6-ply tires at just below the max pressure rating of
> 50PSI. I read about people getting better results with low pressure, so I
> dropped it to 26. Holy cow! That made it a TON worse! Weird.
>
> So tonight I hopped out to the hanger and did a quick measurement with a
> laser level. Held it on the brake disks and measured six feet in front and
> behind the axle, marked it, and calculated toe...came out to 1/2 degree
> toe-out.
>
> I've read so much about this, but so much is conflicting. So now my
> question is has anyone solved their shimmy by going from toe-out to toe-in?
> It sure seems toe-in would work much better, but then I've read people
> claiming the exact opposite.
>
> Assuming I decide to go with toe-in, what's the best way to reset? Drill
> a new hole and put in a new bolt, or drill the existing hole to the next
> size bolt?
>
> Oh, last thing. I didn't verify that each wheel has 1/2 degree toe
> out. I just measured the difference between laser lines front and back, and it
> works out to a total of 1 degree. For all I know, one is set differently
> from the other, but I'll verify that and adjust accordingly if I reset to
> toe-in.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=382840#382840
>
>
>
>
>
>
>
> le, List Admin.
>
>
>
Message 3
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| Subject: | Section 7; Seat Belt installation is now updated and Available |
Section 7 has been revised and is ready for you to view at
http://www.flylightning.net/images/pdf/7SeatBeltInstallation.pdf
It has been revised to clarify the center seat belt attach points for both
EXP and Widetrack LSA gear box installs as they are different.
Thanks
Nick Otterback
Arion Aircraft LLC
R&D Technical Support
931-680-1781
nick@flylightning.net
Message 4
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| Subject: | Re: Shimmy update |
Hi Gerd,
The purpose of the wood fairings solidly bonded to the aluminum gear is to
stiffen it and help it from twisting. The foam method is good if all you're
trying to do is to streamline it, but I don't think it would prevent it fr
om twisting. The interface between the foam and gear would be very weak.
No, I've not added the wood fairings to mine, but will do so after I fly it
and see if I need them. I'm hoping the 1 1/2 degrees toe-in will help in t
hat respect.
The REAL solution would have been to design the landing gear as leaf spring
gear, in my humble opinion. That, or new leaf landing gear legs with round
ends to fit into the existing mount sockets would work. Of course, this wo
uld entail expensive machining and new wheel attach weldments would have to
be designed. Probably too much to ask.
Bernardo-
--- On Tue, 9/11/12, Gerd Nowack <nowacklinden@gmx.de> wrote:
From: Gerd Nowack <nowacklinden@gmx.de>
Subject: Re: Lightning-List: Shimmy update
Bernardo,
I agree with your opinion, that the round gear legs are causing the trouble
, and I like your plan to modify them.
1st:Have you started to make your gear legs or are you still planning.?
2nd: have you (or anyone else!)considered to use model builder`s foam inste
ad of wood? The wood might have more "springiness", but one could make up f
or that with just more (unidirectional) epoxy-glass, maybe even carbon rovi
ngs. And foam- is much easier to shape!
3rd: to save weight it might be a nice idea to sand or mill aluminum from t
he side off the gear legs first, maybe a 1/4 ", total , or .4 "( 1cm)-of co
urse the ends have to remain round to fit their receiving tubes.
Has anybody experience with such a combined aluminum / epoxy- spring?
Well, that is roughly what I have in mind if the shimmy starts shaking my b
aby. During the next days I will bolt the wheel pants on , and then I will
see what happens.
Btw that will be the time when I can publish a few performance data.
And pictures as my contribution for the Lightning Of The Year-contest ;-)
Gerd- D-ELIY , kit 89
-------- Original-Nachricht --------
> Datum: Mon, 10 Sep 2012 20:45:51 -0700 (PDT)
> Von: "Bernard Melendez, Jr." <n45bm@yahoo.com>
> An: lightning-list@matronics.com
> Betreff: Re: Lightning-List: Shimmy update
> Bill,
> Standard practice is for toe IN, not toe out. I put 1 1/2 degrees toe in
> on my plane, but I've yet to test it as I'm not flying yet. The build man
ual
> says 1 degree toe in, but I added another 1/2 degree, I hope it helps.
> Leaf spring gears have less problems with shimmy. I believe that the prob
lem
> with round landing gears is that they are more likely to twist with side
> loads and once that starts, oh well....
> I propose that to help the gear resist twisting motion, shaped wood block
s
> be well bonded to the front and rear of the gear and shaped to an airfoil
> shape, followed by several plies of fiberglass or carbon fiber. Milling t
he
> roundness to match the tapered gear is the trick. That's the hard part.
> If my landing gear exhibits shimmy, that's what I plan to do. The main
> objective would be to stiffen the gear to prevent twisting loads. All thi
s is
> just speculation on my part, but I can't think of a better way to do it.
> Bernardo
>
> Okay, perhaps I'm doing things in a weird order, but I'm still playing
> with shimmy stuff.- The stiffeners I made from fiberglass didn't help.
- I'll
> remove them soon.- I switched to the 6-ply tires, no dice.
>
> I was running the 6-ply tires at just below the max pressure rating of
> 50PSI.- I read about people getting better results with low pressure, s
o I
> dropped it to 26.- Holy cow!- That made it a TON worse!- Weird.
>
> So tonight I hopped out to the hanger and did a quick measurement with a
> laser level.- Held it on the brake disks and measured six feet in front
and
> behind the axle, marked it, and calculated toe...came out to 1/2 degree
> toe-out.
>
> I've read so much about this, but so much is conflicting.- So now my
> question is has anyone solved their shimmy by going from toe-out to toe-i
n?-
> It sure seems toe-in would work much better, but then I've read people
> claiming the exact opposite.
>
> Assuming I decide to go with toe-in, what's the best way to reset?- Dri
ll
> a new hole and put in a new bolt, or drill the existing hole to the next
> size bolt?
>
> Oh, last thing.- I didn't verify that each wheel has 1/2 degree toe
> out.- I just measured the difference between laser lines front and back
, and it
> works out to a total of 1 degree.- For all I know, one is set different
ly
> from the other, but I'll verify that and adjust accordingly if I reset to
> toe-in.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=382840#382840
>
>
>
>
>
>
>
> le, List Admin.
>
>
>
le, List Admin.
Message 5
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The original gear for the Esqual was flat spring steel bar. I don't know
why Francesc changed it, as I have far too stiffer U/C on my Esqual I'd
rather he hadn't.
It also has ended up on the Lightning of course.
In the UK we are mostly on grass and lots of fields are really bumpy so
a little more spring would be good.
Regarding toe in or out. I always figured that the 'toe' was so that
loaded the wheels would point directly where the vehicle is going or
almost. In the case of our gear legs when loaded the legs will tend to
bend out and back.
So toeing out would be bad and getting worse, strange that it seems to
help the shimmy problem in Australia.
Has anyone tried a more flexible tyre? Maybe flat block tread rather
than conventional aero pattern?
Mind you I read less pressure makes the shimmy worse and less pressure
would be more flexible.
I have block tread square tyres but I did have aero on, got the knobbly
ones as my home runway is very rough concrete
I think RVs used to bond wood on and streamline it, this was for shimmy
and streamlining I believe. Though now they just have the fairings.
Aren't RV legs steel? Is that the way to go? A bit heavier but stronger
and probably springier. Anyone know?
Just thinking out load. I don't have it despite having exactly the same
set up on my plane so it baffles me.
I do have a loud tapping from the U/C on bumpy fields but I figure that
is the legs slightly moving in the sockets as they are a little small.
Anybody have that too?
What about the bandy legged light sport lightning, does that have
shimmy?
Regards, Clive
Esqual in UK, round ally gear legs from Arion (not sure if they are
Lightning or Esqual).
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Bernard
Melendez, Jr.
Sent: 11 September 2012 20:24
Subject: Re: Lightning-List: Shimmy update
Hi Gerd,
The purpose of the wood fairings solidly bonded to the aluminum gear is
to stiffen it and help it from twisting. The foam method is good if all
you're trying to do is to streamline it, but I don't think it would
prevent it from twisting. The interface between the foam and gear would
be very weak.
No, I've not added the wood fairings to mine, but will do so after I fly
it and see if I need them. I'm hoping the 1 1/2 degrees toe-in will help
in that respect.
The REAL solution would have been to design the landing gear as leaf
spring gear, in my humble opinion. That, or new leaf landing gear legs
with round ends to fit into the existing mount sockets would work. Of
course, this would entail expensive machining and new wheel attach
weldments would have to be designed. Probably too much to ask.
Bernardo
--- On Tue, 9/11/12, Gerd Nowack <nowacklinden@gmx.de> wrote:
From: Gerd Nowack <nowacklinden@gmx.de>
Subject: Re: Lightning-List: Shimmy update
<nowacklinden@gmx.de>
Bernardo,
I agree with your opinion, that the round gear legs are causing the
trouble , and I like your plan to modify them.
1st:Have you started to make your gear legs or are you still planning.?
2nd: have you (or anyone else!)considered to use model builder`s foam
instead of wood? The wood might have more "springiness", but one could
make up for that with just more (unidirectional) epoxy-glass, maybe even
carbon rovings. And foam is much easier to shape!
3rd: to save weight it might be a nice idea to sand or mill aluminum
from the side off the gear legs first, maybe a 1/4 ", total , or .4 "(
1cm)-of course the ends have to remain round to fit their receiving
tubes.
Has anybody experience with such a combined aluminum / epoxy- spring?
Well, that is roughly what I have in mind if the shimmy starts shaking
my baby. During the next days I will bolt the wheel pants on , and then
I will see what happens.
Btw that will be the time when I can publish a few performance data.
And pictures as my contribution for the Lightning Of The Year-contest
;-)
Gerd D-ELIY , kit 89
-------- Original-Nachricht --------
> Datum: Mon, 10 Sep 2012 20:45:51 -0700 (PDT)
> Von: "Bernard Melendez, Jr." <n45bm@yahoo.com>
> An: lightning-list@matronics.com
> Betreff: Re: Lightning-List: Shimmy update
> Bill,
> Standard practice is for toe IN, not toe out. I put 1 1/2 degrees toe
in
> on my plane, but I've yet to test it as I'm not flying yet. The build
manual
> says 1 degree toe in, but I added another 1/2 degree, I hope it helps.
> Leaf spring gears have less problems with shimmy. I believe that the
problem
> with round landing gears is that they are more likely to twist with
side
> loads and once that starts, oh well....
> I propose that to help the gear resist twisting motion, shaped wood
blocks
> be well bonded to the front and rear of the gear and shaped to an
airfoil
> shape, followed by several plies of fiberglass or carbon fiber.
Milling the
> roundness to match the tapered gear is the trick. That's the hard
part.
> If my landing gear exhibits shimmy, that's what I plan to do. The main
> objective would be to stiffen the gear to prevent twisting loads. All
this is
> just speculation on my part, but I can't think of a better way to do
it.
> Bernardo
>
> Okay, perhaps I'm doing things in a weird order, but I'm still playing
> with shimmy stuff. The stiffeners I made from fiberglass didn't help.
I'll
> remove them soon. I switched to the 6-ply tires, no dice.
>
> I was running the 6-ply tires at just below the max pressure rating of
> 50PSI. I read about people getting better results with low pressure,
so I
> dropped it to 26. Holy cow! That made it a TON worse! Weird.
>
> So tonight I hopped out to the hanger and did a quick measurement with
a
> laser level. Held it on the brake disks and measured six feet in
front and
> behind the axle, marked it, and calculated toe...came out to 1/2
degree
> toe-out.
>
> I've read so much about this, but so much is conflicting. So now my
> question is has anyone solved their shimmy by going from toe-out to
toe-in?
> It sure seems toe-in would work much better, but then I've read people
> claiming the exact opposite.
>
> Assuming I decide to go with toe-in, what's the best way to reset?
Drill
> a new hole and put in a new bolt, or drill the existing hole to the
next
> size bolt?
>
> Oh, last thing. I didn't verify that each wheel has 1/2 degree toe
> out. I just measured the difference between laser lines front and
back, and it
> works out to a total of 1 degree. For all I know, one is set
differently
> from the other, but I'll verify that and adjust accordingly if I reset
to
> toe-in.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=382840#382840
>
>
>
>
>
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