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briana(at)xtra.co.nz
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 Posted: Wed Jan 12, 2011 11:09 am Post subject: Nose wheel pressure |
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I'm doing another annual inspection, the 10th one now, and inflating the tyres in the process. I fitted new main tyres and tubes a year ago and have only had to re-inflate once in that time, and even now the pressure has been maintained pretty well. Previously I had to pump the mains up about every 3 months.
| Quote: | From time to time I still experience a little nosewheel shimmy. I have some friction on the pivot, but maybe not quite enough. Landing too fast is probably the major contributor, but I always try to hold the nosewheel off as long as possible. The question is - - does the tyre pressure in the nosewheel make any difference. I can't say I have noticed it one way or the other. Usually I put about 30 psi in the nosewheel and when I checked yesterday, after a year it was down to about 20 psi. [By the way, it is the larger nosewheel that came with the later Aero Design kits, but with an Asusa aluminium wheel]. If there was some certainty about whether the nosewheel pressure made a difference I would be more careful to maintain it in the right region.
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I had a deal of difficulty getting any friction system to work effectively. I have the original Aero Designs nose leg, but with a later Skystar cast aluminium fork. The reason for the change is that the kit supplied fork was drilled at an angle so the nosewheel was mis-aligned. The later fork is thicker at the pivot point, and also needed to be sleeved for the smaller pivot pin. The additional thickness leaves very little room for Bellville washers so I had to improvise with a single slimmed down version. Hence one flat on the securing nut makes a big difference to the friction, and it is impossible to get it just right. It's either too tight for taxiing or too loose for shimmy.
Has anyone thought of a good way to have nice linear friction in the last 10 years ?
Brian
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mortweaver(at)sbcglobal.n
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| Posted: Wed Jan 12, 2011 1:56 pm Post subject: Nose wheel pressure |
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Brian - Since you can not work with the usual stack of bellevue washers, have you tried working with a bellevue washer of a higher compression rating (offers higher crush resistance)?
Another thought is to insert a flat washer of a dissimilar metal between the existing 2 bellevue washers. Brass may contribute enough friction to work. I also have the Azuzu large wheel option. I find that 20 lbs for the nose wheel inflation pressure to be adequate and cushions touch-down nicely.
Dave Weaver N912GR
--- On Wed, 1/12/11, Brian Anderson <briana(at)xtra.co.nz> wrote:
| Quote: |
From: Brian Anderson <briana(at)xtra.co.nz>
Subject: Nose wheel pressure
To: pulsar-list(at)matronics.com
Date: Wednesday, January 12, 2011, 1:07 PM
--> Pulsar-List message posted by: Brian Anderson <briana(at)xtra.co.nz (briana(at)xtra.co.nz)>
I'm doing another annual inspection, the 10th one now, and inflating the tyres in the process. I fitted new main tyres and tubes a year ago and have only had to re-inflate once in that time, and even now the pressure has been maintained pretty well. Previously I had to pump the mains up about every 3 months.
| Quote: | From time to time I still experience a little nosewheel shimmy. I have some friction on the pivot, but maybe not quite enough. Landing too fast is probably the major contributor, but I always try to hold the nosewheel off as long as possible. The question is - - does the tyre pressure in the nosewheel make any difference. I can't say I have noticed it one way or the other. Usually I put about 30 psi in the nosewheel and when I checked yesterday, after a year it was down to about 20 psi. [By the way, it is the larger nosewheel that came with the later Aero Design kits, but with an Asusa aluminium wheel]. If there was some certainty about whether the nosewheel pressure made a difference I would be more careful to maintain it in the right region.
|
I had a deal of difficulty getting any friction system to work effectively. I have the original Aero Designs nose leg, but with a later Skystar cast aluminium fork. The reason for the change is that the kit supplied fork was drilled at an angle so the nosewheel was mis-aligned. The later fork is thicker at the pivot point, and also needed to be sleeved for the smaller pivot pin. The additional thickness leaves very little room for Bellville washers so I had to improvise with a single slimmed down version. Hence one flat on the securing nut makes a big difference to the friction, and it is impossible to get it just right. It's either too tight for taxiing or too loose for shimmy.
Has anyone thought of a good way to have nice linear friction in the la://www.matronics.com/Navigator?Pulsar-List" target=_blank>http://www.matr Web nbsp; -Matt matronics.com/contribution" target=_blank>http://www.matronics.com/contri================
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[quote][b]
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tkane(at)ida.org
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| Posted: Wed Jan 12, 2011 2:01 pm Post subject: Nose wheel pressure |
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Dear Brian,
Nose wheel shimmy can be reduced with the installation of a fluid damper mounted perpendicular to the direction of travel inside the wheel pant. A small piece of PVC/PCV pipe capped on both ends and partially filled with heavy oil such as automotive differential gear oil can be used. Mount the damper inside the wheel pant behind the nose wheel. When the wheel pant moves to the left the oil will move to the right.
Tom.
--
Tom Kane
407 Nob Hill Drive
Stafford, Virginia 22556
N17575, Pulsar XP, Rotax 912
540.752-1509 home
703.624-2833 cell
703.845-2404 work
On 1/12/11 2:07 PM, "Brian Anderson" <[url=briana(at)xtra.co.nz]briana(at)xtra.co.nz[/url]> wrote:
[quote]--> Pulsar-List message posted by: Brian Anderson <[url=briana(at)xtra.co.nz]briana(at)xtra.co.nz[/url]>
I'm doing another annual inspection, the 10th one now, and inflating the tyres in the process. I fitted new main tyres and tubes a year ago and have only had to re-inflate once in that time, and even now the pressure has been maintained pretty well. Previously I had to pump the mains up about every 3 months.
>From time to time I still experience a little nosewheel shimmy. I have some friction on the pivot, but maybe not quite enough. Landing too fast is probably the major contributor, but I always try to hold the nosewheel off as long as possible. The question is - - does the tyre pressure in the nosewheel make any difference. I can't say I have noticed it one way or the other. Usually I put about 30 psi in the nosewheel and when I checked yesterday, after a year it was down to about 20 psi. [By the way, it is the larger nosewheel that came with the later Aero Design kits, but with an Asusa aluminium wheel]. If there was some certainty about whether the nosewheel pressure made a difference I would be more careful to maintain it in the right region.
I had a deal of difficulty getting any friction system to work effectively. I have the original Aero Designs nose leg, but with a later Skystar cast aluminium fork. The reason for the change is that the kit supplied fork was drilled at an angle so the nosewheel was mis-aligned. The later fork is thicker at the pivot point, and also needed to be sleeved for the smaller pivot pin. The additional thickness leaves very little room for Bellville washers so I had to improvise with a single slimmed down version. Hence one flat on the securing nut makes a big difference to the friction, and it is impossible to get it just right. It's either too tight for taxiing or too loose for shimmy.
Has anyone thought of a good way to have nice linear friction in the last 10 years ?
Brian
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st Email Forum -
ar-List">http://www.matronics.com/Navigator?Pulsar-List
===========
sp; - MATRONICS WEB FORUMS -
ums.matronics.com
===========
sp;- List Contribution Web Site -
sp; -Matt Dralle, List Admin.
http://www.matronics.com/contribution
===========
[b]
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briana(at)xtra.co.nz
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| Posted: Wed Jan 12, 2011 3:43 pm Post subject: Nose wheel pressure |
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Hi Tom,
Well that sounds like an original idea. So the oil acts as a mass that tends to stay stationary as the wheel oscillate back and forth. Have you tried this system. It would be easy to implement.
Brian
On 13/01/2011, at 10:55 AM, Kane, Thomas G wrote:
[quote] Dear Brian,
Nose wheel shimmy can be reduced with the installation of a fluid damper mounted perpendicular to the direction of travel inside the wheel pant. A small piece of PVC/PCV pipe capped on both ends and partially filled with heavy oil such as automotive differential gear oil can be used. Mount the damper inside the wheel pant behind the nose wheel. When the wheel pant moves to the left the oil will move to the right.
Tom.
--
Tom Kane
407 Nob Hill Drive
Stafford, Virginia 22556
N17575, Pulsar XP, Rotax 912
540.752-1509 home
703.624-2833 cell
703.845-2404 work
On 1/12/11 2:07 PM, "Brian Anderson" <[url=x-msg://60/briana(at)xtra.co.nz]briana(at)xtra.co.nz[/url]> wrote:
| Quote: | --> Pulsar-List message posted by: Brian Anderson <[url=x-msg://60/briana(at)xtra.co.nz]briana(at)xtra.co.nz[/url]>
I'm doing another annual inspection, the 10th one now, and inflating the tyres in the process. I fitted new main tyres and tubes a year ago and have only had to re-inflate once in that time, and even now the pressure has been maintained pretty well. Previously I had to pump the mains up about every 3 months.
>From time to time I still experience a little nosewheel shimmy. I have some friction on the pivot, but maybe not quite enough. Landing too fast is probably the major contributor, but I always try to hold the nosewheel off as long as possible. The question is - - does the tyre pressure in the nosewheel make any difference. I can't say I have noticed it one way or the other. Usually I put about 30 psi in the nosewheel and when I checked yesterday, after a year it was down to about 20 psi. [By the way, it is the larger nosewheel that came with the later Aero Design kits, but with an Asusa aluminium wheel]. If there was some certainty about whether the nosewheel pressure made a difference I would be more careful to maintain it in the right region.
I had a deal of difficulty getting any friction system to work effectively. I have the original Aero Designs nose leg, but with a later Skystar cast aluminium fork. The reason for the change is that the kit supplied fork was drilled at an angle so the nosewheel was mis-aligned. The later fork is thicker at the pivot point, and also needed to be sleeved for the smaller pivot pin. The additional thickness leaves very little room for Bellville washers so I had to improvise with a single slimmed down version. Hence one flat on the securing nut makes a big difference to the friction, and it is impossible to get it just right. It's either too tight for taxiing or too loose for shimmy.
Has anyone thought of a good way to have nice linear friction in the last 10 years ?
Brian
===========
st Email Forum -
ar-List">http://www.matronics.com/Navigator?Pulsar-List
===========
sp; - MATRONICS WEB FORUMS -
ums.matronics.com
===========
sp;- List Contribution Web Site -
sp; -Matt Dralle, List Admin.
http://www.matronics.com/contribution
===========
|
[b]
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tkane(at)ida.org
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| Posted: Thu Jan 13, 2011 2:35 am Post subject: Nose wheel pressure |
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Dear Brian,
No, I currently don’t have a need. The bolt carrier on the M-16 rifle has a fluid inside the bolt that dampens its travel to the rear when the rifle is fired. That concept started me thinking. The amount of space inside the pipe available for fluid movement and the viscosity of the fluid are factors in dampening. Since the Pulsar nose wheel shimmy problem varies with speed, an exact solution at a specific speed in not required. Anything to decrease high-speed lateral movement of the wheel pant should be helpful. If a heavy oil does not provide acceptable results then a more viscous liquid should be substituted. I don’t think anyone knows how fast the nose wheel moves so experimentation may be needed.
Tom.
--
Tom Kane
407 Nob Hill Drive
Stafford, Virginia 22556
N17575, Pulsar XP, Rotax 912
540.752-1509 home
703.624-2833 cell
703.845-2404 work
On 1/12/11 6:41 PM, "Brian Anderson" <[url=briana(at)xtra.co.nz]briana(at)xtra.co.nz[/url]> wrote:
[quote]Hi Tom,
Well that sounds like an original idea. So the oil acts as a mass that tends to stay stationary as the wheel oscillate back and forth. Have you tried this system. It would be easy to implement.
Brian
On 13/01/2011, at 10:55 AM, Kane, Thomas G wrote:
| Quote: | Dear Brian,
Nose wheel shimmy can be reduced with the installation of a fluid damper mounted perpendicular to the direction of travel inside the wheel pant. A small piece of PVC/PCV pipe capped on both ends and partially filled with heavy oil such as automotive differential gear oil can be used. Mount the damper inside the wheel pant behind the nose wheel. When the wheel pant moves to the left the oil will move to the right.
Tom.
|
[b]
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rwilhelm(at)dc.rr.com
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| Posted: Thu Jan 13, 2011 7:24 am Post subject: Nose wheel pressure |
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On my Pulsar III I used 2 viscous springs like they use on the tailgate of many hatchbacks. One on each side of the nose gear where the gear attaches to the shock mount, the other ends connect to the firewall at the motor mount. Helped a lot.
Ray Pulsar III/3300
[quote][b]
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briana(at)xtra.co.nz
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| Posted: Thu Jan 13, 2011 11:07 am Post subject: Nose wheel pressure |
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Hi Tom,
It sounds like an idea worth thinking about. I'll have another look at the wheel pant today and see how much room is available. It seems the viscosity needn't be too high, and the tube not filled, otherwise it would act as a solid mass. Perhaps the idea is allowing the tube to move sideways with the wheel pant - - leaving the fluid behind, then when the fluid builds up on one side and the end of the tube catches up it adds mass and slows the movement of the wheel pant.
I'll try to do some more research.
Regards,
Brian
On 13/01/2011, at 11:30 PM, Kane, Thomas G wrote:
| Quote: | Dear Brian,
No, I currently don’t have a need. The bolt carrier on the M-16 rifle has a fluid inside the bolt that dampens its travel to the rear when the rifle is fired. That concept started me thinking. The amount of space inside the pipe available for fluid movement and the viscosity of the fluid are factors in dampening. Since the Pulsar nose wheel shimmy problem varies with speed, an exact solution at a specific speed in not required. Anything to decrease high-speed lateral movement of the wheel pant should be helpful. If a heavy oil does not provide acceptable results then a more viscous liquid should be substituted. I don’t think anyone knows how fast the nose wheel moves so experimentation may be needed.
Tom.
--
Tom Kane
407 Nob Hill Drive
Stafford, Virginia 22556
N17575, Pulsar XP, Rotax 912
540.752-1509 home
703.624-2833 cell
703.845-2404 work
On 1/12/11 6:41 PM, "Brian Anderson" <[url=x-msg://166/briana(at)xtra.co.nz]briana(at)xtra.co.nz[/url]> wrote:
| Quote: | Hi Tom,
Well that sounds like an original idea. So the oil acts as a mass that tends to stay stationary as the wheel oscillate back and forth. Have you tried this system. It would be easy to implement.
Brian
On 13/01/2011, at 10:55 AM, Kane, Thomas G wrote:
| Quote: | Dear Brian,
Nose wheel shimmy can be reduced with the installation of a fluid damper mounted perpendicular to the direction of travel inside the wheel pant. A small piece of PVC/PCV pipe capped on both ends and partially filled with heavy oil such as automotive differential gear oil can be used. Mount the damper inside the wheel pant behind the nose wheel. When the wheel pant moves to the left the oil will move to the right.
Tom.
|
href="http://www.matronics.com/Navigator?Pulsar-List">http://www.matronics.com/Navigator?Pulsar-List
href="http://forums.matronics.com/">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution
|
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[quote][b]
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joekynaston(at)gmail.com
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| Posted: Sun Jan 16, 2011 5:37 am Post subject: Nose wheel pressure |
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Brian and All
be sure to balance your front wheel. I checked mine for balance (plastic wheel) and found it needed 22g of weight.
Now that it is balanced I don't suffer from nosewheel shimmy at all
Joe
XP
Bedfordshire UK
On 13 January 2011 19:04, Brian Anderson <briana(at)xtra.co.nz (briana(at)xtra.co.nz)> wrote:
[quote] Hi Tom,
It sounds like an idea worth thinking about. I'll have another look at the wheel pant today and see how much room is available. It seems the viscosity needn't be too high, and the tube not filled, otherwise it would act as a solid mass. Perhaps the idea is allowing the tube to move sideways with the wheel pant - - leaving the fluid behind, then when the fluid builds up on one side and the end of the tube catches up it adds mass and slows the movement of the wheel pant.
I'll try to do some more research.
Regards,
Brian
On 13/01/2011, at 11:30 PM, Kane, Thomas G wrote:
| Quote: | Dear Brian,
No, I currently don’t have a need. The bolt carrier on the M-16 rifle has a fluid inside the bolt that dampens its travel to the rear when the rifle is fired. That concept started me thinking. The amount of space inside the pipe available for fluid movement and the viscosity of the fluid are factors in dampening. Since the Pulsar nose wheel shimmy problem varies with speed, an exact solution at a specific speed in not required. Anything to decrease high-speed lateral movement of the wheel pant should be helpful. If a heavy oil does not provide acceptable results then a more viscous liquid should be substituted. I don’t think anyone knows how fast the nose wheel moves so experimentation may be needed.
Tom.
--
Tom Kane
407 Nob Hill Drive
Stafford, Virginia 22556
N17575, Pulsar XP, Rotax 912
540.752-1509 home
703.624-2833 cell
703.845-2404 work
On 1/12/11 6:41 PM, "Brian Anderson" <briana(at)xtra.co.nz> wrote:
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arget="_blank">http://www.matronics.com/Navigator?Pulsar-List
ttp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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