On Wed, 15 Oct 2003 13:23:12 -0700, Rich Stowell wrote:

Kevin Horton wrote in message
...

One very small nit to pick - I know a lot of people think a dutch roll
is a manoeuvre where the pilot it actively making the aircraft roll back
and forth around a point. But the term properly means a combined yawing
and rolling oscillation that the aircraft does all by itself.

It is hard to have clear communication when we have words that mean
different things to different people.

For a rant on the mis-use of the term dutch roll, see:
http://www.douglasdc3.com/sohn/41.htm


Hi Kevin,

Pilots picking nits? Who would have guessed ; )

The English language is very colorful, and many terms have multiple
meanings depending on the context. In the context of the aerobatic
environment, Dutch Roll (note the capitalization, which is customary in
this context) is well understood by aerobatic pilots to describe a
specific coordination maneuver as opposed to the inherent instability
dutch roll common in swept wing aircraft.

While it is true that sometimes the use of certain terms can lead to
confusion, we nevertheless frequently use terminology that has multiple
meanings. For example, ask the airline pilot who is strapping into his
aerobatic mount on his day off from his flying job to explain and perform
a Dutch Roll, and he will know exactly what is being asked of him.
However, ask him to define dutch roll while he's at 35,000 feet in the
left seat of his airliner, and he'll likely delve into the aerodynamic
issues involved with dutch roll instability.

Yes, context is important; but to imply that a particlar phrase or word
can and must have one and only one meaning might be a fruitless exercise
indeed! Consider the following:


Rich,

Yeah, I was probably a bit over-the-top with my post. And my perspective
is perhaps clouded by my military and flight test background.

I guess the important point to reel in is that we need to be aware of
when a term could have more than one meaning, and provide enough context
to make the intended meaning clear. I first heard the term Dutch Roll
used to describe a coordination manoeuvre a couple of months ago. Before
that, if I went flying with you and you asked me to do a Dutch Roll, you
would have been baffled to watch me do a rudder doublet and count the yaw
overshoots.

Poor lateral-directional dynamic stabilty (a.k.a. dutch roll) is not
just an issue with swept-wing yets. I've heard many a V-tail Bonanza
driver complain about the tail wag, which is just a variant of dutch roll.

I'd tell you to keep the blue side up, but you probably don't want to do
that

Fly safe,
--
Kevin Horton
Ottawa, Canada
e-mail: khorton02(_at_)rogers(_dot_)com
http://go.phpwebhosting.com/~khorton/rv8/