Today's Message Index:
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1. 08:48 AM - Re: 50 Tail wheel shimmy (flir47)
2. 04:23 PM - Re: Re: 50 Tail wheel shimmy (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
3. 08:22 PM - Re: Re: 50 Tail wheel shimmy (Roger Kemp)
4. 11:30 PM - What are you barking for????? (JN(Canada))
Message 1
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| Subject: | Re: 50 Tail wheel shimmy |
mark.bitterlich(at)navy.m wrote:
> The problem is HOW you go about adjusting it so that you CAN move the
> unlock position all the way forward.
>
> If you take the fairing at the right horizontal stab root off, you will
> be able to see the mechanism that controls the up and down movement of
> the tail wheel locking pin. The adjustment that you see at this
> location is there to control the DEPTH of the pins movement into the
> locking ring hole located just above the tail wheel tire. Adjusting this
> does not really solve the problem very well, because it is possible to
> adjust the pin down too far, and then... You simply run out of pin and
> it drops down through the locking pin hole with cable hanging on behind
> it.
>
> You will notice that the cable itself is connected to a BOLT on the
> shaft that connects the left and right horizontal stabs together. If
> you move the cable attachment to another bolt you can make it to where
> the pin pulls out (upwards) ONLY when the stick is moved ALL the way
> forward.
>
> However, when you do this... You will notice that when you start to pull
> the stick all the way AFT.... There will be so much extra slack in the
> cable that the pin will drop DOWN and then OUT of the locking ring hole
>
> To prevent THIS from happening, you have to build a cable snubber. This
> can be something so simple as a bolt and a nut with a vertical groove
> cut down the middle of the threaded portion of the bolt itself. Picture
> that in your mind. You slide the cable through the vertical cut in the
> bolt, and then when you screw on a nut.. The nut will PINCH the cable to
> the top of the cut slot as you tighten it. You then position this
> device on the cable so that you control how far DOWN the LOCKING PIN can
> go as you pull the stick AFT.
>
> A picture would really help here.
>
> However, if you pull the fairing off, and then look at it as you read
> this message, I am betting that it will become obvious.
>
> I invented this method a few years ago, and have been using this lashup
> ever since... It really stopped the tail wheel shimmy cold... At least
> the VIOLENT type that just eats your tail wheels ALIVE. I used to get
> just months out of the tail wheels, now I get years.
>
> Mark Bitterlich
> N50YK
>
>
>
>
> --
Mark
I'm going to fab a seperate lever and lock with an idiot light for the TW lock.
When and if I get it done I may post some pics.....
--------
You built and fly an RV.......BIG DEAL!!!!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=107740#107740
Message 2
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| Subject: | Re: 50 Tail wheel shimmy |
Using a stand alone control lever for tailwheel lock:
In many ways, I think that is the VERY BEST SOLUTION TO THE PROBLEM!
Simple, completely pilot controlled, and not tied in with controls that
might conflict with tail wheel locking needs.
I wrote an article about tailwheel shimmy in my YAK 50 around 6 or 7
years ago. It discussed how to adjust/move the cable attach point and
install the snubber so as to allow the 50's tailwheel to remain locked
through-out the complete flight. The way I verified what was causing
the mess to begin with was by having a friend flying close form on
landing filming the tailwheel with a VHS recorder/camera.
Since we have re-opened this conversation, a point came up that Tom
Johnson has educated me about concerning YAK 50 tailwheel locking pins.
The pin on a lot of 50's has a SHOULDER on it that prevents it from
coming down too far and allowing the pin to fall completely right out of
the hole it slides in to. Tom Johnson has looked at three YAK-50's that
have this shoulder on the pin. I own TWO 50's (one is a parts only
aircraft) and neither of them have a shoulder that prevent the pin from
coming right on out the bottom. Now, either the pins shoulder wore off
of what I have, or the hole it goes in is bigger, or it is somehow a
different part. I need to do a close examination and take pictures to
figure out why his three are different from my two.
However the real issue being discussed is whether it is ok to rely on
the shoulder to keep the pin from sliding down too far, or is it better
to add the snubber, so that the cable ITSELF keeps the pin from going
down too far. In my case, it HAD to be a snubber (or some like device
such as a cable swage). In Tom's case, his pin "shoulder" allowed him
not to use a snubber and instead rely on the shoulder.
If you follow the Russian instructions for setting the pin depth, the
cable and not the shoulder prevent pin over-travel and the shoulder is
there apparently as a backup. That is an ASSUMPTION on my part and is
not verified. Thus, I lean towards still using a snubber on the cable
and not relying on a shoulder. Keep in mind though that with my
airplane I never had the option.
It ends up being the call of every individual how to go about doing it.
Tom Johnson's method does not require you to move the cable attach
point. My method does require that you move it, because I want that
stick ALL the way forward to unlock the tailwheel, not 80%, but ALL the
way. Either method ends up with the cable going slack when you then
pull the stick all the way back. I add a snubber on the cable to
prevent the cable from ever going slack and thus also keeping the pin
from sliding down too far in that condition. Tom is allowing he cable
to go slack and is relying on the shoulder on the pin which so far he
has seen on every 50 he has looked at, but that mine do not have.
Either method works.
Bottom line, if you make these adjustments to prevent shimmy, be careful
that you understand all the ramifications of what you are doing.
r/s,
Mark Bitterlich
N50YK
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of flir47
Sent: Wednesday, April 18, 2007 11:48
Subject: Yak-List: Re: 50 Tail wheel shimmy
Mark
I'm going to fab a seperate lever and lock with an idiot light for the
TW lock.
When and if I get it done I may post some pics.....
--------
You built and fly an RV.......BIG DEAL!!!!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=107740#107740
Message 3
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| Subject: | Re: 50 Tail wheel shimmy |
Mark,
What year is your 50? Mine is a 78 and I do not recall seeing a shoulder on
the locking pin. I will double check tomorrow PM.
I have adjusted my cable all the way out in the manor that is shown in
Tom's article. The cable will not adjust far enough out to allow full
forward stick throw. I go about 2-3 inches past neutral on the stick. I did
that after the picture that you saw was taken when I figured out that was
part of my problem. Those that have flown formation on me since have not
commented on the tailwheel being canted off center. The last pictures taken
after that have not shown it to be canted off center. I have not had
another episode of sudden kicking of the tail with touch down either.
Doc
> [Original Message]
> From: Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E
<mark.bitterlich@navy.mil>
> To: <yak-list@matronics.com>
> Date: 4/18/2007 6:28:53 PM
> Subject: RE: Yak-List: Re: 50 Tail wheel shimmy
>
MALS-14 64E" <mark.bitterlich@navy.mil>
>
> Using a stand alone control lever for tailwheel lock:
>
> In many ways, I think that is the VERY BEST SOLUTION TO THE PROBLEM!
>
> Simple, completely pilot controlled, and not tied in with controls that
> might conflict with tail wheel locking needs.
>
> I wrote an article about tailwheel shimmy in my YAK 50 around 6 or 7
> years ago. It discussed how to adjust/move the cable attach point and
> install the snubber so as to allow the 50's tailwheel to remain locked
> through-out the complete flight. The way I verified what was causing
> the mess to begin with was by having a friend flying close form on
> landing filming the tailwheel with a VHS recorder/camera.
>
> Since we have re-opened this conversation, a point came up that Tom
> Johnson has educated me about concerning YAK 50 tailwheel locking pins.
> The pin on a lot of 50's has a SHOULDER on it that prevents it from
> coming down too far and allowing the pin to fall completely right out of
> the hole it slides in to. Tom Johnson has looked at three YAK-50's that
> have this shoulder on the pin. I own TWO 50's (one is a parts only
> aircraft) and neither of them have a shoulder that prevent the pin from
> coming right on out the bottom. Now, either the pins shoulder wore off
> of what I have, or the hole it goes in is bigger, or it is somehow a
> different part. I need to do a close examination and take pictures to
> figure out why his three are different from my two.
>
> However the real issue being discussed is whether it is ok to rely on
> the shoulder to keep the pin from sliding down too far, or is it better
> to add the snubber, so that the cable ITSELF keeps the pin from going
> down too far. In my case, it HAD to be a snubber (or some like device
> such as a cable swage). In Tom's case, his pin "shoulder" allowed him
> not to use a snubber and instead rely on the shoulder.
>
> If you follow the Russian instructions for setting the pin depth, the
> cable and not the shoulder prevent pin over-travel and the shoulder is
> there apparently as a backup. That is an ASSUMPTION on my part and is
> not verified. Thus, I lean towards still using a snubber on the cable
> and not relying on a shoulder. Keep in mind though that with my
> airplane I never had the option.
>
> It ends up being the call of every individual how to go about doing it.
> Tom Johnson's method does not require you to move the cable attach
> point. My method does require that you move it, because I want that
> stick ALL the way forward to unlock the tailwheel, not 80%, but ALL the
> way. Either method ends up with the cable going slack when you then
> pull the stick all the way back. I add a snubber on the cable to
> prevent the cable from ever going slack and thus also keeping the pin
> from sliding down too far in that condition. Tom is allowing he cable
> to go slack and is relying on the shoulder on the pin which so far he
> has seen on every 50 he has looked at, but that mine do not have.
> Either method works.
>
> Bottom line, if you make these adjustments to prevent shimmy, be careful
> that you understand all the ramifications of what you are doing.
>
> r/s,
>
> Mark Bitterlich
> N50YK
>
>
> -----Original Message-----
> From: owner-yak-list-server@matronics.com
> [mailto:owner-yak-list-server@matronics.com] On Behalf Of flir47
> Sent: Wednesday, April 18, 2007 11:48
> To: yak-list@matronics.com
> Subject: Yak-List: Re: 50 Tail wheel shimmy
>
>
> Mark
>
> I'm going to fab a seperate lever and lock with an idiot light for the
> TW lock.
>
> When and if I get it done I may post some pics.....
>
> --------
> You built and fly an RV.......BIG DEAL!!!!
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=107740#107740
>
>
Message 4
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| Subject: | What are you barking for????? |
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