From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: Small-tail Lancair stability
To: lml
Date: Sun, 27 Aug 2006 23:40:15 -0400
Message-ID: <web-1351658@logan.com>
In-Reply-To: <002801c6c9e7$7b117d90$108b6041@mark1>
References: <002801c6c9e7$7b117d90$108b6041@mark1>
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Posted for "Mark Ravinski" <mjrav@comcast.net>:

  Small-tail Lancair
  
  
   Hi George,
  I did some more flight testing yesterday.  I guess our planes may be more
alike than different.
  I have duplicated what you are talking about to some extent.
  My Lancair will exhibit this "nose bobbing" both right and left and both
clean and dirty.  It can be made to happen at a variety of speeds as well and
depends on rudder displacement more than anything else.
For me, that's more than half rudder.
  So, in practical terms, if I'm too high around a base turn and need to slip,
I'll still be well above the ground and have excess speed (maybe something
over 100 mph or so).  The nose bobbing is minimal under these conditions and
I've always ignored it.  It does not lead to an "out of control" situation.
  On final, half rudder will handle a crosswind of 15 to 20 kts or so and this
bobbing does become a limiting situation above that.  I have had to divert
once in my 1000 hours.
  At my home field, I know that if I can safely get below treetop level, the
crosswind dies sown somewhat and I MAY be able to land.  When the windsock is
out straight on a dead cross, I may not feel safe even at treetop.
  
  I'm not at all sure of the cause but assume it has to do with getting the
tail too far sideways and out of good smooth airflow.  Maybe the air coming
off a wing has something to do with it. - or the turbulent air around the
fuselage when it goes sideways.
  
  If your plane exhibits the problem much more one way than the other, I'd 
look
to see if your engine is aligned exactly right.  Maybe a couple of washers as
shims at a mount would make a difference.  Also, check that you do get the
same rudder displacement both ways.  Maybe a rigging issue.
  
  
  
Fly safe,
  Mark Ravinski