REFLECTOR:caster of NG
KeithHallsten
reflector@tvbf.org
Tue, 17 Jun 2003 08:53:09 -0700
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No! The bottom-forward cant of the axis is called "rake" and needs to =
be positive to provide stability. The shape of the fork gets the wheel =
contact point well behind the center of rotation (which is called =
"trail") to provide self-centering. As Nolan Fredrick pointed out, this =
is what makes motorcycles and bicycles stable.
It's analogous to balancing control surfaces; the forward weighting on a =
control surface is sort of like "rake" and the large surface subject to =
aerodynamic forces behind the hinge is sort of like "trail".
Keith Hallsten - balancing control surfaces!
----- Original Message -----=20
From: Wayne Owens=20
To: reflector@tvbf.org=20
Sent: Tuesday, June 17, 2003 5:25 AM
Subject: Re: REFLECTOR:caster of NG
You do mean forward at the top don't you?
Wayne
Mine is one of the old style (like everything of mine) assemblies that =
includes a 5 inch wide piece of channel where the "ears" attach. I am =
relocating the holes about 1/2 inch forward. That will change it to a 2 =
degree negative (bottom rearward) angle.
Wayne
----- Original Message -----=20
From: AnnSam=20
To: reflector@tvbf.org=20
Sent: Monday, June 16, 2003 10:53 PM
Subject: RE: REFLECTOR:caster of NG
You better believe it. It's what keeps it from shimmying. Castor is =
reward, Kingpin inclination is foward.
-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On =
Behalf Of Wayne Owens
Sent: Monday, June 16, 2003 9:48 PM
To: reflector@tvbf.org
Subject: REFLECTOR:caster of NG
Today I started to install my new NG strut. After leveling the =
plane I found the new strut was sloped 2 degrees but the in the wrong =
direction. IE the bottom of the strut was further forward than the top =
of the fork (bottom of the washer). Brendan confirmed this was correct =
for me.
I don't believe it.
Caster must be reward for the wheel to be self centering. I think =
I now see why I could not beat the shimmy problem before. I asked the =
fellow who designed the current form of Cessna's NG. He said he designed =
12 degrees negative for Cessna.
Various of my mechanical engineer friends confirm that with the =
positive angle the weight of the aircraft will try to force the wheel =
out of trail.
I suspect my old strut had this same problem. Live and learn.=20
Wayne
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<DIV><FONT face=3DArial size=3D2>No! The bottom-forward cant of =
the axis is=20
called "rake" and needs to be positive to provide stability. The =
shape of=20
the fork gets the wheel contact point well behind the center of rotation =
(which=20
is called "trail") to provide self-centering. As Nolan Fredrick =
pointed=20
out, this is what makes motorcycles and bicycles stable.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>It's analogous to balancing =
control surfaces;=20
the forward weighting on a control surface is sort of like "rake" and =
the large=20
surface subject to aerodynamic forces behind the hinge is sort =
of like=20
"trail".</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Keith Hallsten - balancing control=20
surfaces!</FONT></DIV>
<DIV> </DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3Dwamowens@bellsouth.net =
href=3D"mailto:wamowens@bellsouth.net">Wayne=20
Owens</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Dreflector@tvbf.org=20
href=3D"mailto:reflector@tvbf.org">reflector@tvbf.org</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Tuesday, June 17, 2003 =
5:25=20
AM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: REFLECTOR:caster =
of NG</DIV>
<DIV><BR></DIV>
<DIV><FONT face=3DArial size=3D2>You do mean forward at the top don't=20
you?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Wayne</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Mine is one of the old style (like =
everything of=20
mine) assemblies that includes a 5 inch wide piece of channel =
where the=20
"ears" attach. I am relocating the holes about 1/2 inch forward. That=20
will change it to a 2 degree negative (bottom rearward)=20
angle.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Wayne</FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3Dannsam1@earthlink.net=20
href=3D"mailto:annsam1@earthlink.net">AnnSam</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Dreflector@tvbf.org=20
href=3D"mailto:reflector@tvbf.org">reflector@tvbf.org</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Monday, June 16, 2003 =
10:53=20
PM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> RE: REFLECTOR:caster =
of=20
NG</DIV>
<DIV><BR></DIV>
<DIV><SPAN class=3D812334802-17062003><FONT face=3DArial =
color=3D#0000ff=20
size=3D2>You better believe it. It's what keeps it from shimmying. =
Castor is=20
reward, Kingpin inclination is foward.</FONT></SPAN></DIV>
<BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">
<DIV class=3DOutlookMessageHeader dir=3Dltr align=3Dleft><FONT =
face=3DTahoma=20
size=3D2>-----Original Message-----<BR><B>From:</B> <A=20
=
href=3D"mailto:reflector-admin@tvbf.org">reflector-admin@tvbf.org</A>=20
[mailto:reflector-admin@tvbf.org]<B>On Behalf Of </B>Wayne=20
Owens<BR><B>Sent:</B> Monday, June 16, 2003 9:48 PM<BR><B>To:</B> =
<A=20
=
href=3D"mailto:reflector@tvbf.org">reflector@tvbf.org</A><BR><B>Subject:<=
/B>=20
REFLECTOR:caster of NG<BR><BR></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Today I started to install my new =
NG strut.=20
After leveling the plane I found the new strut was sloped 2 =
degrees =20
but the in the wrong direction. IE the bottom of the strut was =
further=20
forward than the top of the fork (bottom of the =
washer). =20
Brendan confirmed this was correct </FONT><FONT face=3DArial =
size=3D2>for=20
me.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2> I don't believe =
it.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial><FONT size=3D2><FONT size=3D+0>Caster must =
be reward for=20
the wheel to be self centering. I think I now see why I could not =
beat the=20
shimmy problem before. I asked the fellow who designed the =
current=20
form of Cessna's NG. He said he designed 12 degrees negative for=20
Cessna</FONT>.</FONT></FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Various of my mechanical engineer =
friends=20
confirm that with the positive angle the weight of the aircraft =
will try=20
to force the wheel out of trail.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I suspect my old strut had this =
same problem.=20
Live and learn. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial=20
size=3D2>Wayne</FONT></DIV></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BODY>=
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