Today's Message Index:
----------------------
1. 05:27 AM - Re: Lightning Newsletter Booklets (Caithness Manor)
2. 07:09 AM - Landing Gear and shimmy (Nick Otterback)
3. 07:19 AM - Re: Landing Gear and shimmy (Dennis W. Wilt)
4. 09:04 AM - Re: Landing Gear and shimmy (Nick Otterback)
5. 10:31 AM - Re: Landing Gear and shimmy (Dennis W. Wilt)
Message 1
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Subject: | Re: Lightning Newsletter Booklets |
I'll do some research Buz and let you know.
Cheers.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=382915#382915
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Subject: | Landing Gear and shimmy |
The original esqual gear was a flat plate steel type which bolted to the
fuselage thru the 6 bolts holding the spar box in. the overturn angle of
the
gear (how much it angled from the fuselage) was very steep. This
transfers
more load to the attach points and surrounding structure because it wont
flex as much. The EXP tube gear has greater angle and less load transfer
but
is more subject to shimmy being a round rod. The Lightning EXP gear is
7075T6, plenty sturdy for the intended application. The Equal round gear
is
a different type alloy, although I do not remember what, experience in
the
field says it=92s something lighter in alloy than the 7075T6.
A spring steel gear is not necessarily stronger than aluminum. The RV
are
spring steel an too subject to shimmy, I have experienced in a few of
the
RV models I have flown. IT is just a matter of a round tube subject to
it.
The Steel has a higher frequency and may not exhibit a shimmy at the
same
speed and aircraft weight of the aluminum. I have even experienced in a
Rans
S7S with round tube gear, just at a lower speed around 12-15mph on roll
out.
What we have found works here, covered multiple times. Is about 1 degree
toe
out on the EXP gear. This coupled with air-pressure in the 22-25psi
range
with keep drag on the gear and minimize it from moving around . Higher
air-pressure just causes the tire to skip and shimmy better. Also it
seems
that the Better tires help, I believe from the squared off tire tread
they
have instead of the round tread.
If all of this does not help we have almost completely eliminated it on
aircraft when bonding hardwood to the gear leg. Simply clamping the hard
wood to the Leg will not help. I have used wood like Oak. A piece of
hard
wood that it fitted to within =BC=94 of the bottom of the fuselage to
the lower
socket. Mill out one side =BD round to fit the gear leg. The wood should
be at
least the 1=94 wide that the gear is, by about 2=94 aft of it. Mill the
trailing
edge to fit under the leg fairing. Lightly sand the aft side of the gear
leg. Bond the gear leg to the back of the gear leg with 24hr epoxy and
flox,
clamp in place to cure. After cure wrap the wood and leg with 10oz
glass.
The glass should be cut in sections the same length as the hard wood by
about 7=94 wide to completely wrap the gear. Also it is critical to cut
these
sections out of the glass cloth on a 45 degree bias to the weave. IF you
simply use the glass in the direction of the weave it will not resist
the
fore and aft movement of the gear. I have use about 4 layers of glass. I
suppose if you wished 2 layers of carbon cut a laminated the same way
should
work.
The wood does stiffen the gear, but keeps the spring it needs, What the
wood
does is change the frequency that the gear shimmy=92s at and helps
dampen out
any that may occur. Lighter or softer materials will not work. Simply
adding
glass to the gear will not help.
As for the LSA wide track landing gear. We set the gear at 0 toe,
straight
ahead, with the wings off the aircraft. Actually we set this with the
spar
box out of the aircraft during the build process. With a little weight
on
the gear it may toe out slightly. We very rarely run into shimmy with
the
big gear, if we do it usually goes back to over inflated tires, flat
spots,
or infrequent flying that flat spots the tires and creates a skip. The
overturn angle of the LSA gear is much greater than the EXP gear. The
LSA
gear is 2.125=94 at the top and 1.25=94 at the bottom VS 1.375=94 and
1=94 on the
EXP gear just for FYI.
Nick Otterback
Arion Aircraft LLC
R&D Technical Support
931-680-1781
nick@flylightning.net
Message 3
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Subject: | Re: Landing Gear and shimmy |
My EA-B version of the LSA has the LSA gear just because they are supposed
to be a bit more sturdy. My only complaint with the lightning gear is that
it is not very forgiving on landing. It is pretty stiff, so if you happen
to land a little hard, you will bounce and that means a go around for me.
Some of you may be better at saving such a landing, but I choose to go aro
und and do it again, hopefully without the bounce.
I set my toe to 0 degrees without weight on the wheels and keep my air pres
sure around 25 psi. I have never had the shimmy.
Have a wonderful day,
Dennis
N616DW (Arion Lightning S/N 132)
-----Original Message-----
From: Nick Otterback <nick@flylightning.net>
Sent: Wed, Sep 12, 2012 10:09 am
Subject: Lightning-List: Landing Gear and shimmy
The original esqual gear was a flat plate steel type which bolted to the fu
selage thru the 6 bolts holding the spar box in. the overturn angle of the
gear (how much it angled from the fuselage) was very steep. This transfers
more load to the attach points and surrounding structure because it wont fl
ex as much. The EXP tube gear has greater angle and less load transfer but
is more subject to shimmy being a round rod. The Lightning EXP gear is 7075
T6, plenty sturdy for the intended application. The Equal round gear is a d
ifferent type alloy, although I do not remember what, experience in the fie
ld says it=99s something lighter in alloy than the 7075T6.
A spring steel gear is not necessarily stronger than aluminum. The RV are s
pring steel an too subject to shimmy, I have experienced in a few of the R
V models I have flown. IT is just a matter of a round tube subject to it. T
he Steel has a higher frequency and may not exhibit a shimmy at the same sp
eed and aircraft weight of the aluminum. I have even experienced in a Rans
S7S with round tube gear, just at a lower speed around 12-15mph on roll out
.
What we have found works here, covered multiple times. Is about 1 degree to
e out on the EXP gear. This coupled with air-pressure in the 22-25psi range
with keep drag on the gear and minimize it from moving around . Higher air
-pressure just causes the tire to skip and shimmy better. Also it seems tha
t the Better tires help, I believe from the squared off tire tread they hav
e instead of the round tread.
If all of this does not help we have almost completely eliminated it on air
craft when bonding hardwood to the gear leg. Simply clamping the hard wood
to the Leg will not help. I have used wood like Oak. A piece of hard wood t
hat it fitted to within =C2=BC=9D of the bottom of the fuselage to th
e lower socket. Mill out one side =C2=BD round to fit the gear leg. The woo
d should be at least the 1=9D wide that the gear is, by about 2
=9D aft of it. Mill the trailing edge to fit under the leg fairing. Lightly
sand the aft side of the gear leg. Bond the gear leg to the back of the ge
ar leg with 24hr epoxy and flox, clamp in place to cure. After cure wrap th
e wood and leg with 10oz glass. The glass should be cut in sections the sam
e length as the hard wood by about 7=9D wide to completely wrap the g
ear. Also it is critical to cut these sections out of the glass cloth on a
45 degree bias to the weave. IF you simply use the glass in the direction o
f the weave it will not resist the fore and aft movement of the gear. I hav
e use about 4 layers of glass. I suppose if you wished 2 layers of carbon c
ut a laminated the same way should work.
The wood does stiffen the gear, but keeps the spring it needs, What the woo
d does is change the frequency that the gear shimmy=99s at and helps
dampen out any that may occur. Lighter or softer materials will not work. S
imply adding glass to the gear will not help.
As for the LSA wide track landing gear. We set the gear at 0 toe, straight
ahead, with the wings off the aircraft. Actually we set this with the spar
box out of the aircraft during the build process. With a little weight on t
he gear it may toe out slightly. We very rarely run into shimmy with the bi
g gear, if we do it usually goes back to over inflated tires, flat spots, o
r infrequent flying that flat spots the tires and creates a skip. The overt
urn angle of the LSA gear is much greater than the EXP gear. The LSA gear i
s 2.125=9D at the top and 1.25=9D at the bottom VS 1.375
=9D and 1=9D on the EXP gear just for FYI.
Nick Otterback
Arion Aircraft LLC
R&D Technical Support
931-680-1781
nick@flylightning.net
Message 4
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Subject: | Landing Gear and shimmy |
I think you might mean springy not stiff. During drop test at gross
weight, we have nearly 6=9D deflection of the landing gear system.
The little tube in a tube is an easy way to check deflection, set
against the ground before the drop and see how far it gets displaced.
Usually the bounce comes from the nose gear return and the aircraft
going back into a flight attitude with sufficient speed to fly.
Attached some pics for fun. The drop test were the funnest testing we
did, along with destructive testing of the wing.
Nick
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of Dennis
W. Wilt
Sent: Wednesday, September 12, 2012 9:18 AM
Subject: Re: Lightning-List: Landing Gear and shimmy
My EA-B version of the LSA has the LSA gear just because they are
supposed to be a bit more sturdy. My only complaint with the lightning
gear is that it is not very forgiving on landing. It is pretty stiff,
so if you happen to land a little hard, you will bounce and that means a
go around for me. Some of you may be better at saving such a landing,
but I choose to go around and do it again, hopefully without the bounce.
I set my toe to 0 degrees without weight on the wheels and keep my air
pressure around 25 psi. I have never had the shimmy.
Have a wonderful day,
Dennis
N616DW (Arion Lightning <http://www.flylightning.net/> S/N 132)
-----Original Message-----
From: Nick Otterback <nick@flylightning.net>
Sent: Wed, Sep 12, 2012 10:09 am
Subject: Lightning-List: Landing Gear and shimmy
The original esqual gear was a flat plate steel type which bolted to the
fuselage thru the 6 bolts holding the spar box in. the overturn angle of
the gear (how much it angled from the fuselage) was very steep. This
transfers more load to the attach points and surrounding structure
because it wont flex as much. The EXP tube gear has greater angle and
less load transfer but is more subject to shimmy being a round rod. The
Lightning EXP gear is 7075T6, plenty sturdy for the intended
application. The Equal round gear is a different type alloy, although I
do not remember what, experience in the field says it=99s
something lighter in alloy than the 7075T6.
A spring steel gear is not necessarily stronger than aluminum. The RV
are spring steel an too subject to shimmy, I have experienced in a few
of the RV models I have flown. IT is just a matter of a round tube
subject to it. The Steel has a higher frequency and may not exhibit a
shimmy at the same speed and aircraft weight of the aluminum. I have
even experienced in a Rans S7S with round tube gear, just at a lower
speed around 12-15mph on roll out.
What we have found works here, covered multiple times. Is about 1 degree
toe out on the EXP gear. This coupled with air-pressure in the 22-25psi
range with keep drag on the gear and minimize it from moving around .
Higher air-pressure just causes the tire to skip and shimmy better. Also
it seems that the Better tires help, I believe from the squared off tire
tread they have instead of the round tread.
If all of this does not help we have almost completely eliminated it on
aircraft when bonding hardwood to the gear leg. Simply clamping the hard
wood to the Leg will not help. I have used wood like Oak. A piece of
hard wood that it fitted to within =C2=BC=9D of the bottom of the
fuselage to the lower socket. Mill out one side =C2=BD round to fit the
gear leg. The wood should be at least the 1=9D wide that the gear
is, by about 2=9D aft of it. Mill the trailing edge to fit under
the leg fairing. Lightly sand the aft side of the gear leg. Bond the
gear leg to the back of the gear leg with 24hr epoxy and flox, clamp in
place to cure. After cure wrap the wood and leg with 10oz glass. The
glass should be cut in sections the same length as the hard wood by
about 7=9D wide to completely wrap the gear. Also it is critical
to cut these sections out of the glass cloth on a 45 degree bias to the
weave. IF you simply use the glass in the direction of the weave it will
not resist the fore and aft movement of the gear. I have use about 4
layers of glass. I suppose if you wished 2 layers of carbon cut a
laminated the same way should work.
The wood does stiffen the gear, but keeps the spring it needs, What the
wood does is change the frequency that the gear shimmy=99s at and
helps dampen out any that may occur. Lighter or softer materials will
not work. Simply adding glass to the gear will not help.
As for the LSA wide track landing gear. We set the gear at 0 toe,
straight ahead, with the wings off the aircraft. Actually we set this
with the spar box out of the aircraft during the build process. With a
little weight on the gear it may toe out slightly. We very rarely run
into shimmy with the big gear, if we do it usually goes back to over
inflated tires, flat spots, or infrequent flying that flat spots the
tires and creates a skip. The overturn angle of the LSA gear is much
greater than the EXP gear. The LSA gear is 2.125=9D at the top and
1.25=9D at the bottom VS 1.375=9D and 1=9D on the EXP
gear just for FYI.
Nick Otterback
Arion Aircraft LLC
R&D Technical Support
931-680-1781
nick@flylightning.net
" target="_blank"
saprocessedanchor="true">http://www.matronics.com/Navigator?Lightning-L
ist
processedanchor="true">http://forums.matronics.com
_blank" saprocessedanchor="true">http://www.matronics.com/contribution
Message 5
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Subject: | Re: Landing Gear and shimmy |
Nick, could be, but I know of at least 2 that was a bounce off the mains.
Cool pictures, I would like to see video.
Have a wonderful day,
Dennis
N616DW (Arion Lightning S/N 132)
-----Original Message-----
From: Nick Otterback <nick@flylightning.net>
Sent: Wed, Sep 12, 2012 12:07 pm
Subject: RE: Lightning-List: Landing Gear and shimmy
I think you might mean springy not stiff. During drop test at gross weight,
we have nearly 6=9D deflection of the landing gear system. The littl
e tube in a tube is an easy way to check deflection, set against the ground
before the drop and see how far it gets displaced. Usually the bounce come
s from the nose gear return and the aircraft going back into a flight attit
ude with sufficient speed to fly.
Attached some pics for fun. The drop test were the funnest testing we did,
along with destructive testing of the wing.
Nick
From: owner-lightning-list-server@matronics.com [mailto:owner-lightning-lis
t-server@matronics.com] On Behalf Of Dennis W. Wilt
Sent: Wednesday, September 12, 2012 9:18 AM
Subject: Re: Lightning-List: Landing Gear and shimmy
My EA-B version of the LSA has the LSA gear just because they are supposed
to be a bit more sturdy. My only complaint with the lightning gear is that
it is not very forgiving on landing. It is pretty stiff, so if you happen
to land a little hard, you will bounce and that means a go around for me.
Some of you may be better at saving such a landing, but I choose to go aro
und and do it again, hopefully without the bounce.
I set my toe to 0 degrees without weight on the wheels and keep my air pres
sure around 25 psi. I have never had the shimmy.
Have a wonderful day,
Dennis
N616DW (Arion Lightning S/N 132)
-----Original Message-----
From: Nick Otterback <nick@flylightning.net>
Sent: Wed, Sep 12, 2012 10:09 am
Subject: Lightning-List: Landing Gear and shimmy
The original esqual gear was a flat plate steel type which bolted to the fu
selage thru the 6 bolts holding the spar box in. the overturn angle of the
gear (how much it angled from the fuselage) was very steep. This transfers
more load to the attach points and surrounding structure because it wont fl
ex as much. The EXP tube gear has greater angle and less load transfer but
is more subject to shimmy being a round rod. The Lightning EXP gear is 7075
T6, plenty sturdy for the intended application. The Equal round gear is a d
ifferent type alloy, although I do not remember what, experience in the fie
ld says it=99s something lighter in alloy than the 7075T6.
A spring steel gear is not necessarily stronger than aluminum. The RV are s
pring steel an too subject to shimmy, I have experienced in a few of the R
V models I have flown. IT is just a matter of a round tube subject to it. T
he Steel has a higher frequency and may not exhibit a shimmy at the same sp
eed and aircraft weight of the aluminum. I have even experienced in a Rans
S7S with round tube gear, just at a lower speed around 12-15mph on roll out
.
What we have found works here, covered multiple times. Is about 1 degree to
e out on the EXP gear. This coupled with air-pressure in the 22-25psi range
with keep drag on the gear and minimize it from moving around . Higher air
-pressure just causes the tire to skip and shimmy better. Also it seems tha
t the Better tires help, I believe from the squared off tire tread they hav
e instead of the round tread.
If all of this does not help we have almost completely eliminated it on air
craft when bonding hardwood to the gear leg. Simply clamping the hard wood
to the Leg will not help. I have used wood like Oak. A piece of hard wood t
hat it fitted to within =C2=BC=9D of the bottom of the fuselage to th
e lower socket. Mill out one side =C2=BD round to fit the gear leg. The woo
d should be at least the 1=9D wide that the gear is, by about 2
=9D aft of it. Mill the trailing edge to fit under the leg fairing. Lightly
sand the aft side of the gear leg. Bond the gear leg to the back of the ge
ar leg with 24hr epoxy and flox, clamp in place to cure. After cure wrap th
e wood and leg with 10oz glass. The glass should be cut in sections the sam
e length as the hard wood by about 7=9D wide to completely wrap the g
ear. Also it is critical to cut these sections out of the glass cloth on a
45 degree bias to the weave. IF you simply use the glass in the direction o
f the weave it will not resist the fore and aft movement of the gear. I hav
e use about 4 layers of glass. I suppose if you wished 2 layers of carbon c
ut a laminated the same way should work.
The wood does stiffen the gear, but keeps the spring it needs, What the woo
d does is change the frequency that the gear shimmy=99s at and helps
dampen out any that may occur. Lighter or softer materials will not work. S
imply adding glass to the gear will not help.
As for the LSA wide track landing gear. We set the gear at 0 toe, straight
ahead, with the wings off the aircraft. Actually we set this with the spar
box out of the aircraft during the build process. With a little weight on t
he gear it may toe out slightly. We very rarely run into shimmy with the bi
g gear, if we do it usually goes back to over inflated tires, flat spots, o
r infrequent flying that flat spots the tires and creates a skip. The overt
urn angle of the LSA gear is much greater than the EXP gear. The LSA gear i
s 2.125=9D at the top and 1.25=9D at the bottom VS 1.375
=9D and 1=9D on the EXP gear just for FYI.
Nick Otterback
Arion Aircraft LLC
R&D Technical Support
931-680-1781
nick@flylightning.net
" target="_blank" saprocessedanchor="true">http://www.matronics.com/Nav
igator?Lightning-List
processedanchor="true">http://forums.matronics.com
_blank" saprocessedanchor="true">http://www.matronics.com/contribution
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