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Nosewheel Shimmy

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freefolk(at)screaming.net
Guest

Posted: Fri May 19, 2006 12:43 am Post subject: Nosewheel Shimmy

The current high winds in the UK remind me of the problem which has =

occurred to me twice this year after a crosswind departure from home =

base (Old Sarum - a fairly bumpy grass airfield) with a subsequent =

landing on a hard runway without significant crosswind.  Having =

taken-off with a 15-25 knot crosswind (from the right in both cases - =

the "best" side), severe nosewheel shimmy was encountered on landing, =

which continued until the aircraft was brought to rest.  Not pleasant =

waiting for something to break, and unable to do anything about it.  =

Fortunately no damage on either occasion.  Has anyone else encountered =

this problem, and is there a remedy?  The friction on the (so called) =

shimmy damper was checked as between 8-9 Kgs on both occasions.  Ian =

Rickard has suggested that I reduce friction to around 5-6 Kgs in the =

hope that slipstream will straighten the nosewheel in flight from any =

inadvertant sidethrust imparted during rotation.



Brian Tarmar

G-OBJT 055 Classic Trigear,  912S/Warpdrive and XS front/mods

65 hours and still smiling when it ain't shimmying!

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rholder(at)avnet.co.uk
Guest

Posted: Fri May 19, 2006 1:14 am Post subject: Nosewheel Shimmy

Brian and Pat Tarmar wrote:



 	  Quote: 	
		   The current high winds in the UK remind me of the 

 problem which has occurred to me twice this year after

 a crosswind departure from home base (Old Sarum - a

 fairly bumpy grass airfield) with a subsequent landing

 on a hard runway without significant crosswind. Having

 taken-off with a 15-25 knot crosswind (from the right

 in both cases - the "best" side), severe nosewheel

 shimmy was encountered on landing, which continued

 until the aircraft was brought to rest. Not pleasant

 waiting for something to break, and unable to do

 anything about it. Fortunately no damage on either

 occasion. Has anyone else encountered this problem, and

 is there a remedy? The friction on the (so called)

 shimmy damper was checked as between 8-9 Kgs on both

 occasions. Ian Rickard has suggested that I reduce

 friction to around 5-6 Kgs in the hope that slipstream

 will straighten the nosewheel in flight from any

 inadvertant sidethrust imparted during rotation.


	


 	  Quote: 	
		   Brian Tarmar G-OBJT 055 Classic Trigear,

 912S/Warpdrive and XS front/mods 65 hours and still

 smiling when it ain't shimmying!


	


I would say the opposite ! The shimmy is the nosewheel

moving from side to side on the ground when landing. Any

deflection from central on take-off may make the first

shimmy movement but once the oscillation starts looseness

of the damper will actually make it worse.



I would suggest tightening up the "big nut" one flat and

trying it again. Maybe two flats. If it is too tight it

will not want to steer on the ground (but it won't shimmy !)



I took mine apart on my annual and found that there were a

lot of grooves in the plastic (damping) disc and there was

some cr*p in there as well. I cleaned it all up, including

the metal surfaces and then I turned the plastic disc over

to give me a new smooth surface. I had it tight before and

the movement was in jerks. Now it is very smooth, and no

shimmy. And it steers on the ground (most of the time !)



G-OWWW is exactly the same as yours - Classic Tri-Gear, XS

FWF, 912S but I have an Airmaster.



Richard

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peter.rees01(at)tiscali.c
Guest

Posted: Fri May 19, 2006 1:45 am Post subject: Nosewheel Shimmy

I have to agree with Richard



Our nose wheel damper seems to requrie fairly regular checking and tightening

- when it gets a little loose, we do get a bit of shimmy - that said, we've

been flying out of rochester (grass) and landing at hard runways with the

friction as low as about 3kg with very little discernable shimmy.



Don't know if you have to do anything about balancing the wheel in any way

 	  Quote: 	
		  -- Original Message --

Date: Fri, 19 May 2006 10:11:56 +0100

From: Richard Holder <rholder(at)avnet.co.uk>

To: europa-list(at)matronics.com

Subject: Re: Nosewheel Shimmy

Reply-To: europa-list(at)matronics.com




Brian and Pat Tarmar wrote:



> The current high winds in the UK remind me of the 

> problem which has occurred to me twice this year after

> a crosswind departure from home base (Old Sarum - a

> fairly bumpy grass airfield) with a subsequent landing

> on a hard runway without significant crosswind. Having

> taken-off with a 15-25 knot crosswind (from the right

> in both cases - the "best" side), severe nosewheel

> shimmy was encountered on landing, which continued

> until the aircraft was brought to rest. Not pleasant

> waiting for something to break, and unable to do

> anything about it. Fortunately no damage on either

> occasion. Has anyone else encountered this problem, and

> is there a remedy? The friction on the (so called)

> shimmy damper was checked as between 8-9 Kgs on both

> occasions. Ian Rickard has suggested that I reduce

> friction to around 5-6 Kgs in the hope that slipstream

> will straighten the nosewheel in flight from any

> inadvertant sidethrust imparted during rotation.



> Brian Tarmar G-OBJT 055 Classic Trigear,

> 912S/Warpdrive and XS front/mods 65 hours and still

> smiling when it ain't shimmying!



I would say the opposite ! The shimmy is the nosewheel

moving from side to side on the ground when landing. Any

deflection from central on take-off may make the first

shimmy movement but once the oscillation starts looseness

of the damper will actually make it worse.



I would suggest tightening up the "big nut" one flat and

trying it again. Maybe two flats. If it is too tight it

will not want to steer on the ground (but it won't shimmy !)



I took mine apart on my annual and found that there were a

lot of grooves in the plastic (damping) disc and there was

some cr*p in there as well. I cleaned it all up, including

the metal surfaces and then I turned the plastic disc over

to give me a new smooth surface. I had it tight before and

the movement was in jerks. Now it is very smooth, and no

shimmy. And it steers on the ground (most of the time !)



G-OWWW is exactly the same as yours - Classic Tri-Gear, XS

FWF, 912S but I have an Airmaster.



Richard

 

 

 




	




___________________________________________________________



Tiscali Broadband from 14.99 with free setup!

http://www.tiscali.co.uk/products/broadband/

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ptag.dev(at)tiscali.co.uk
Guest

Posted: Fri May 19, 2006 1:45 am Post subject: Nosewheel Shimmy

Hi! Brian

IMHO increase the shimmy damper load to 12kg and take off with the stick

held back to get the nose "flying" as early as possible. On Landing keep

the stick back and so reduce the weight on the nose wheel even at slow

speeds it reduces the weight on the wheel which has to be good news for

it.

My take off procedure is always to set up the line by differential

braking then simultaneously hit full right rudder as you hit full

throttle to keep the take off line. Only very rarely is the right rudder

relaxed during the entire take off run and I can never remember

requiring any left rudder in fact I take up the attitude that I have

only one leg.(this is with right hand tractor prop wash)



Regards

Bob Harrison G-PTAG Europa MKI/Jabiru 3300

--

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ward.t(at)xtra.co.nz
Guest

Posted: Fri May 19, 2006 5:01 pm Post subject: Nosewheel Shimmy

Solution;

Conversion kit to convert to the wonderful Monowheel!!!!

Sorry, couldn't help myself, no offense.

Cheers,

Tim

 	  Quote: 	
		   

 From: "Brian and Pat Tarmar" <freefolk(at)screaming.net>

 Date: 2006/05/19 Fri PM 08:37:42 GMT+12:00

 To: <europa-list(at)matronics.com>

 Subject: Nosewheel Shimmy

 

 

 

 The current high winds in the UK remind me of the problem which has 

 occurred to me twice this year after a crosswind departure from home 

 base (Old Sarum - a fairly bumpy grass airfield) with a subsequent 

 landing on a hard runway without significant crosswind.  Having 

 taken-off with a 15-25 knot crosswind (from the right in both cases - 

 the "best" side), severe nosewheel shimmy was encountered on landing, 

 which continued until the aircraft was brought to rest.  Not pleasant 

 waiting for something to break, and unable to do anything about it.  

 Fortunately no damage on either occasion.  Has anyone else encountered 

 this problem, and is there a remedy?  The friction on the (so called) 

 shimmy damper was checked as between 8-9 Kgs on both occasions.  Ian 

 Rickard has suggested that I reduce friction to around 5-6 Kgs in the 

 hope that slipstream will straighten the nosewheel in flight from any 

 inadvertant sidethrust imparted during rotation.

 

 Brian Tarmar

 G-OBJT 055 Classic Trigear,  912S/Warpdrive and XS front/mods

 65 hours and still smiling when it ain't shimmying!

 

 

 

 

 

 

  

  

  

 

 

 

 


	


Tim Ward

12 Waiwetu Street

Fendalton

Christchurch.

Ph. 0064 33515166

ward.t(at)xtra.co.nz

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jrm03(at)bigpond.com
Guest

Posted: Fri May 26, 2006 2:11 am Post subject: Nosewheel Shimmy

Thank you Steve for the info. on DAMPING GREASE. Several of us in OZ will 

have some grease in a few days.

Could you please advise if you still use the recommended 8-9 kg dampening 

stiffness with the grease or is some other

figure more suitable



John Moore  # 142

---

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freefolk(at)screaming.net
Guest

Posted: Thu Jun 01, 2006 12:21 am Post subject: Nosewheel Shimmy

Thanks to the words of Steve Vestuti on this forum last week I believe =

we may have cured the nosewheel shimmy experienced on hard runways.  The =

British agent for Nye Lubricants Inc, (www.newgatesimms.co.uk) was =

extremely helpful and sent two 50grm pots of damping grease for me to =

try.  I decided to use the less thick of the two (NYE NYOGEL 767A) first =

and coated both the shaft and washer.  Test flying in a quartering 15kts =

crosswind with high touchdown speed resulted in no shimmy, and best of =

all the braking required to turn had been reduced to light fingertip =

pressure and accuracy of control never before experienced.  Lubricating =

the "friction" washer naturally make it impossible to achieve 8-9kgs of =

static friction before the nosewheel turned, but by cranking the shaft =

nut up more than before (Bob you are making me nervous now!!) I achieved =

a "snatch" value on the spring balance of 8 kg and 2kgs before the wheel =

started to move with a steady pull.  I now intend experimenting with NYE =

PG44A grease which is the thickest grease in their range, in the hope =

that the shaft nut can be backed off some for the same friction figures.



My thanks to Steve for introducing me to damping grease, a subject I had =

never heard of previously. =20



and to Bob Harrison - sorry to hear about the lost nosewheel and =

consequent damage.  Roll pins never did get my vote.

Brian Tarmar  G-OBJT Classic Trigear XS Front 912S=20

75 hours and smile fast returning

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