Message-Id: <5.1.0.14.2.20020418225842.04d9c850@lancaironline.net>
Date: Thu, 18 Apr 2002 22:59:14 -0400
To: lml@lancaironline.net
From: "Robert Smiley" <rsmiley@centurytel.net> (by way of Marv Kaye <marvkaye@lancaironline.net>)
Subject: Re: [LML] Re: Brake pads and tires  Brakes on front wheels.
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; format=flowed

Let's see how this plays out.  The nose wheel is on a moment arm of about 2
feet long.  The pivot bolt is about 6-7 inches long or about 1/2 foot to
handle side loads.  The pads holding the two bearings are about 6 inches
apart.  Lets apply a 1000 lb front load on the nose wheel. That is 2000 ft
lbs.  Do you think the motor mounts can take that load suddenly applied?
How about a 1000-2000 ft lb side load on that six inch moment arm   1500lbs
X 2ft = 3000ft lbs.  3000ft lbsdivided by .5ft = 6,000lb load on each
bearing? That's a lot of force twisting the motor mount.  Can the motor
mount take a three ton load? Loads on the motor mounts caused by the motor
in flight may  probably be gradually applied and the plane will give and
come along following the propeller,(snap rolls and aerobatics excepted).

locking the nose wheel brake if the wheel is slightly turned or out of
alinement of the forward motion of the aircraft could cause an unusual side
load.  Also, there is the principle that static friction is greater than
sliding friction in physical terms.  That is, do not slide the wheels, you
get better traction.  Sliding friction is less.  Sometimes when we brake we
hover about that point ie sliding, not sliding while trying to stop the
craft.

I would surmise sudden impact loads like braking would require some
redesign.  The main gear are shorter coupled and have a long moment arm
between the front and rear pivot points.

This might be a few of the reasons not to have brakes on the front wheels of
smaller general aviation aircraft.

Bob Smiley
N94RJ