Dutch Roll

I just asked my daughter the blue-water sailor about this. She never
heard of Dutch roll, but thought it perhaps came from the motion of a
round-bottomed boat popular when the Dutch ruled the ocean waves
(think Henry Hudson).

She confirmed that a boat can oscillate off a set heading in certain
combinations of wind and wave. Sometimes, she said, it might be
impossible to steer 210 without moving the wheel constantly. But if
you change to 212, you can hold the course just fine.

She called the motion fishtailing

On Mon, 03 May 2004 17:04:16 -0400, Cub Driver
wrote:

It's also properly
used for the motion of a ship with a following sea.

Actually, a ship with a following sea pitches up and down, and in the
worst case is pooped.

A ship with a sea off the stern wallows, but is still pitching. It's a
corkscrew motion, say rolling to port while diving down, then rolling
to starboard while climbing up. Very sick-making.

I never though of either motion as a Dutch roll, and it is not really
similar to Dutch roll in an aircraft.

all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
The Piper Cub Forum www.pipercubforum.com
Viva Bush! blog www.vivabush.org

all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
The Piper Cub Forum www.pipercubforum.com
Viva Bush! blog www.vivabush.org

Cub Driver wrote:

I just asked my daughter the blue-water sailor about this. She never
heard of Dutch roll, but thought it perhaps came from the motion of a
round-bottomed boat popular when the Dutch ruled the ocean waves
(think Henry Hudson).

Yes, that's the origin. The Dutch had a need for large
cargo and shallow draft, so Dutch-built ships tended to
perform a pronounced pitch-yaw-roll motion in following
seas. It's the origin of the "Dutch Roll" label used in
aerodynamics.
Todd Pattist
(Remove DONTSPAMME from address to email reply.)
___
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Share what you learn.

I just asked my daughter the blue-water sailor about this. She never
heard of Dutch roll, but thought it perhaps came from the motion of a
round-bottomed boat popular when the Dutch ruled the ocean waves
(think Henry Hudson).

Okay, last night I asked my son-in-law. He pointed out that if there
is anything bad in nautical usage, it gets the adjective Dutch. (Not
just nautical, I suppose. There is also Dutch treat, which was
considered de trop when I was a lad but which has since evidently
become acceptable.)

all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
The Piper Cub Forum www.pipercubforum.com
Viva Bush! blog www.vivabush.org

Todd Pattist wrote

The term is correctly used for both the intentional flight
maneuver that you think he's thinking of (alternating motion
on the roll axis without corresponding yaw) and the dynamic
instability problem you describe below.

Neither of my three Flight Instruction manuals, Jeppesen, FAA,
and Kershner make any mention of a "Dutch Roll" co-ordination
maneuver.

From http://www.mountainflying.com/adverse2.htm

Adverse Yaw - 2
TRAINING MANEUVER
(This is sometimes improperly called a "Dutch roll")
A training maneuver, called the training roll or coordination roll,
is often introduced early during primary flight training to teach
the pilot to cope with adverse yaw. It is mostly forgotten after
the private certificate is obtained. Many instructors consider the
training roll maneuver to be of greater importance in teaching some
one to fly than chandelles, lazy eights, or other commercial pilot
maneuvers. A pilot getting into a different airplane can determine
the amount of rudder that is required for proper coordination with
the ailerons by using this maneuver.
-------------------------------------------------------------------

From William Kershner's "The Flight Instructor's Manual"

And, for Pete's sake, don't call this maneuver a "Dutch roll."
Dutch roll, a stability and control term, is a condition of a
coupling of lateral-directional oscillations with the nose yawing
as the airplane rolls from bank to bank; the object here is to
keep the nose on the point."
--------------------------------------------------------------------

Bob Moore

Bob Moore wrote

Well....a Dutch Roll is probably not what you understand it to be,
particularly if you have not flown swept-wing transport aircraft.
The aileron/rudder drill sometimes taught to student pilots is not
a Dutch Roll.

Well said Bob!

Chuck

The aileron/rudder drill sometimes taught to student pilots is not
a Dutch Roll.

What is the proper name for that (other than "the aileron/rudder drill
sometimes taught to student pilots"

Jose

--
(for Email, make the obvious changes in my address)

"Teacherjh" wrote in message
...
The aileron/rudder drill sometimes taught to student pilots is not
a Dutch Roll.

What is the proper name for that (other than "the aileron/rudder drill
sometimes taught to student pilots"

Jose

--
(for Email, make the obvious changes in my address)


5 proper names (acronyms) for that Dutch Roll aileron/rudder drill:


1. Dr Boffin's drill:

Stop Pilot Induced Occillation (SPIO)!


2. Miss Murphy's Drill:

Freeze Fingers & Feet (FF&F)!


3. Robby Robot's Drill:

Pleaze Engaze Yaw Damper (PEYD)!


4. Jack Ass's Drill:

Stop Stirring That Panhas (SSTP)!


5. Dutch Uncle's Drill:

U Betterr Stop Drrinking (UBSD)!

;-)

Dutch roll is roll due to yaw in a swept wing aircraft. It is more
pronounced than that experienced in a relatively straight wing aircraft.
Also, since swept wing aircraft are more frequently flown at high altitudes
where the air is thinner and mach transitions can occur it is generally
considered only a swept wing phenomenon. see
http://142.26.194.131/aerodynamics1/...ity/Page5.html

--

B-58 Hustler History: http://members.cox.net/dschmidt1/
-

"SelwayKid" wrote in message
m...
So what is your understanding of a Dutch Roll? It is interesting to me
the various understandings of this manuever, how it is performed and
its origins.
I've got my own that I was taught by a CFI over 45 years ago and have
taught to virtually every student I've had over the years, including
helicopters.
Ol Shy & Bashful CFI - Airplanes and Rotorcraft Helicopters,
Instrument Rotorcraft and Airplanes, Multiengine, Gold Seal (1967)

(SelwayKid) wrote:
So what is your understanding of a Dutch Roll?

Mmmmm.... Duuuutch Rooooool