"Dutch" roll

[fireflybob]

Why is Dutch Roll "dutch"?

[zlin77]

I believe , due to the continuing rolling gait of ice skaters as they traversed the frozen canals in Holland.

[Mad (Flt) Scientist]

Thats the explanation I was always given.

[BOAC]

http://www.pprune.org/forums/showthread.php?t=234291&highlight=dutch+roll

[stator vane]

dutch courage--

is that not strongly connected with a few beers as well?

[Old Smokey]

The particular genre of Aviation mythology that I subscribe to credits the origin of the term "Dutch Roll" as coming from a Boeing engineer engaged in the development of the new B47 bomber, and noticing the similarity between it's strange "swish tailing" and the delightful oscillations of Dutch girl's bottoms whilst skating.

Now, that's my story and I'm sticking to it ('cos I like Dutch girl's bottoms too).:E

Regards,

Old Smokey

[scramjet]

Hi does anyone know if Bristow (2002) "Ace the Technical Pilot Interview" p31 is definatively incorrect. Bristow writes "...... This causes the outer wing to travel faster and to become more straight on to the relative airflow (in effect, decreasing the sweep angle of the wing and increasing its aspect ratio). Both these phenomona will create more lift. (At the same time, the inner wing will travel slower and in effect, becomes more swept relative to the airflow, and both these phenonoma will reduce its lift. Therefore, a marked bank occurs to the point where the outer, upward-moving wing stalls and loses all lift, and therefore the wing drops, causing a roll to the stalled wing and thus leading to the sequence being repeated in the opposite direction. ..........."
Webb (1971) "Fly the Wing" p25, writes "....... if you were to cause one wing to get ahead of the other by yawing the aircraft with too much rudder. The wing going ahead would produce more lift and climb. Eventually the aircraft would slip, the low wing would produce more lift, and the aircraft would roll back in the opposite direction. This is Dutch Roll." Webb goes on to explain that it is usually pilot induced and can happen "close to the ground, right on flare for landing or in V2 climb after cutting an engine at V1 on takeoff."

Now Wikipedia and other WWW references would appear to support Webb's version eg roll then slip (nose into direction of slip) then dominant lateral stability lifts the low wing, followed by weaker directional stability yaws back over too far roll and yaw combined produce Dutch roll.

Thom & Kermode say didly squat, ordered but havent received Davies HTBJ as of yet, so havent got any other reference material. If anyone has a definative answer, I would be most grateful, or can they both versions occur at different altitudes?

[BOAC]

Well, I hope no-one is relying on 'Bristow' for an interview if that quote refers to Dutch Roll! Your italics highlight the error. Things have to be pretty dire to get to a 'stall' with Dutch Roll. Go with Webb et al.

D R is a complex inter-reaction of lateral and directional stability including rolling moment due to sideslip on the fin.

I expect you have reviewed the excellent coverage on PPRune I quoted?

[Mad (Flt) Scientist]

The mention of stall during Dutch Roll totally discredits anything else in the explanation; that's, simply, nonsense.

[scramjet]

Thanks for that, assymetric stalling of a wing didnt seem right, glad I kept asking questions.

Cheers
:)