REFLECTOR:Nose Gear Shimmy

[Ronnie Brown]

Chuck,
On the 70 kts, have you tried the VG's?  Mine touches down at 70, stalls at
65.  But I have the big wings on the small fuselage. Handles good at low
speeds too.

See ya,
Ronnie

----- Original Message -----
From: "Chuck Jensen" <cjensen@dts9000.com>
To: <reflector@tvbf.org>
Sent: Tuesday, August 19, 2003 5:16 PM
Subject: RE: REFLECTOR:Nose Gear Shimmy


| John,
|
| Glad it made a difference.  You may want to progressively loosen the fork
| nut a little at a time.  I'm running 20 psig right now and a tap on the
| brake will turn the nose.  When I get a chance, I'm going to take again
| measure the force required to turn the nose. I can say for certain it is a
| "bunch less" than it was before but that's a just a qualitative
observation
| and means nothing.  Will post a good number when I have it.
|
| Congrats on the 70kn.  The only time I see 70kn is with all three planted.
|
| chuck
|
| -----Original Message-----
| From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On Behalf
Of
| John Dibble
| Sent: Tuesday, August 19, 2003 9:58 AM
| To: reflector@tvbf.org
| Subject: Re: REFLECTOR:Nose Gear Shimmy
|
|
| Well, Chuck, it works like a charm!  I reduced the nose pressure from 40
to
| 18 psig
| and no shimmy at high speeds.  Of course, as life goes, my test flight was
a
| perfect
| landing, touching down on the numbers at 70 kn, so I didn't give it the
acid
| test.
| However the following day after 6 hours in the air, it seemed that the
| Franklin was
| not running smoothly at any prop pitch setting (it was probably just that
I
| was
| fatigued, or does the engine get fatigued too?), so I had an unplanned,
and
| less-than-perfect landing at 80+kn at Punxsutawney (3000 ft, and, no, I
| didn't see the
| woodchuck).  Again, no shimmy at the maximum braking a Matco can offer.  I
| do get some
| shimmy at ~ 15 kn, so ultimately I will balance the wheel, but the higher
| speed is
| most important.  I haven't loosened the nut yet, but will do that soon for
| better
| steering.
| BTW, my flying club is having a fly-in breakfast on 9/1 (Labor Day).  We
| have a 3000
| ft grass strip in the middle of the Finger Lakes (NY).  Dundee - D48.  If
| anyone is
| interested I will provide more info.
|
| John
|
| Chuck Jensen wrote:
|
| > Well, in answer to John's query about the pressure I carry in the nose
| tire,
| > and contrary to Steve's experience, I found the softer-the-better, at
| least
| > to the point that the tire is "squishy" when pilot/copilot is loaded.
On
| my
| > first post, I was going to put in the pressures, then I thought that I
| might
| > just be showing/confirming my ignorance.
| >
| > At that risk, the initial pressure was 16.5#, which was a shock when I
| took
| > the reading because usually a smaller tire will have a higher pressure
and
| I
| > run my mains at 40#.  So, I pressured the nose to 35#, which resulted in
| the
| > shimmy.  When I reduced it back to 15.0#, the shimmy was gone.  I then
| > tightened the washers 1/3 turn to cinch them up a bit.  I haven't tried
| > increasing the air pressure since tightening the washers.  I'm going to
| > locate a good grass strip by my home base before I do that!
| >
| > Previously, I had the washers really tightened down and got tired of
| having
| > to "punch" the brakes to get the nose to break loose for steering.  I
| > disassembled the nose gear (it was pretty dry and grabby), cleaned,
buffed
| > and regreased everything.  When I put it back together, I tightened it
to
| be
| > somewhat less (though not measured) than the 15-20# recommended
break-away
| > force.  This worked great, easy to steer, until I increased the tire
| > pressure and made the tire hard.  My theory is the slightly softer tire
| may
| > incur greater friction and less bounce which reduces shimmy tendency,
| though
| > Scott's experience is directly contrary.
| >
| > A possible side benefit of the soft tire is less stress on the nose gear
| > during landing, particularly a hard one.  (I've never done one, you
| > understand, but I hear stories about others with lesser piloting
skills.)
| > The slight compression of the front tire would seem likely to reduce the
| > impact-shock if your nose drops on the runway instead of greasing it on
| like
| > I always do.
| >
| > Chuck
| > With ocean property in Arizona.
|
| _______________________________________________
| To change your email address, visit
| http://www.tvbf.org/mailman/listinfo/reflector
|
| Visit the gallery!  tvbf:jamaicangoose
| _______________________________________________
| To change your email address, visit
http://www.tvbf.org/mailman/listinfo/reflector
|
| Visit the gallery!  tvbf:jamaicangoose