[NSRCA-discussion] Weather Vane or Crab

[moleski at canisius.edu]

Winston E Batchelor wrote:

> Thanks George

> I really didn't want to argue with Doug.

> ... I was in no way experienced enough to make a correction. IN fact it alomost
> blew me onto the shoulder of the road ...

I suspect that you experience on the bike and other people's experiences
with weathervaning of pattern planes are examples of "tacit knowledge,"
an idea developed by Michael Polanyi.

The vast majority of people do not know what rules they are following
when they ride a bike.  They acquire the skill tacitly (silently) and
don't even realize what they themselves are doing to maintain their
balance.  The corrections are quick and intuitive, beneath the level
of consciousness.

The trick that we use to maintain our balance is to steer into
a fall.  If we're falling to the right, we swing the bars to the
right.  That causes the frame to straighten up.  It may go past
neutral and start falling to the left.  If so, we swing the
bars to the left.

This is very evident at super slow speeds.

To disrupt our balance so that we can make a turn, the
first thing we do is to turn AWAY from the way we want to
go.  To initiate a right-hand turn, we swing the bars to the
left, which causes us to start falling to the right; then
we swing the bars to the right to stop the fall, but not
so far to the right that we come upright--we lean into
the turn.  When it's time to come out of the turn,
we pull the handle bars more to the right, which
throws us toward the left and causes the frame to
come upright.

Video of robot motorbike in which the designer briefly
explains the principle:

http://www.youtube.com/watch?v=XOgkNh_IPjU&mode=related&search=

In the case of perceived "automatic compensation for the
wind," I suggest that people are setting the groundtrack
for the plane without even knowing that they are doing it.
When they get the plane tracking straight across the ground,
it will be properly yawed into the crosswind.  It is
the pilot who achieves the balance between the force of
the wind trying to carry the plane off the line and the
force needed to compensate for that which comes from
yawing the plane into the wind.  It happens so fast and
is so natural that people think the plane is doing it--or,
in the case of the wind unsettling your balance, you thought
that the motorcycle itself is doing the balancing act.

				Marty