From: "Gary Casey" <glcasey@adelphia.net>
To: <lancair.list@olsusa.com>
Subject: trim tab flutter
Date: Wed, 3 Apr 2002 05:35:34 -0800
Message-ID: <NEBBIBKBKLGPNKKOGMMBIEOAEFAB.glcasey@adelphia.net>
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Importance: Normal
In-Reply-To: <20020403063746.AAA10228@pop3.olsusa.com>
Reply-To: lancair.list@olsusa.com

          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>
>>>>>>>>>>>>>>>>
This question for the aerodynamicists out there (both real and amateur):

    How come trim tabs don't have to be counter balanced?  Seems that they
are subject to flutter too as are all foil surfaces.  I suspect that trim
>>>>>>>>>>>>>>

Here is an answer from another amateur:  The trim tab probably would flutter
and possibly cause damage except that the control mechanism is usually very
rigid, preventing the flutter.  In our case a jack-screw right in the
control surface.  I do have a service bulletin from Lancair recommending
installation of a "friction device" apparently intended to prevent flutter
if the link to the actuator becomes disconnected.  Friction would be bad for
a control surface, but not a problem for a trim tab.  Look at all the
production aircraft and they have some sort of non-reversing mechanism very
close to the trim tab.  The long cables could fall off and the tab will stay
firmly locked in place.  Reminds me to look much closer at the pins holding
the very large trim tab on my C177 stabilator.

Gary Casey
ES project
C177RG


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
LML website:   http://members.olsusa.com/mkaye/maillist.html
LML Builders' Bookstore:   http://www.buildersbooks.com/lancair
Please remember that purchases from the Builders' Bookstore
assist with the management of the LML.

Please send your photos and drawings to marvkaye@olsusa.com.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>