There is a common misconception of maneuvering speed among pilots that
somehow has been interpreted to be the maximum speed that will not
cause airframe damage with full and abrupt control deflections. THIS
IS WRONG! The November 2001 crash of the AA Airbus in New York was
determined to be from abrupt rudder deflections below maneuvering speed
resulting in the loss of the vertical fin.
http://www.flyingmag.com/article.asp...article_id=527
Maneuvering speed only relates to a limiting speed for wing protection
in a positive mode. Therefore, any full deflection of controls, other
than the elevator in a stick back mode, could result in failure of the
airframe. Also, since the wing is the only surface defined under
maneuvering speed, there could be a possible failure of elevator,
ailerons, fuselage, etc. with abrupt deflections.
http://www.x-plane.com/myths.html
In the USA, aircraft certification standards for maneuvering speed are
typically determined at gross weight in a clean configuration. As
mentioned in other posts, flying at weights below gross, or with flaps,
will cause a lower stall speed and a corresponding reduction in
maneuvering speed. The maximum positive g load subjected by the wing
before a stall will occur in any given configuration is calculated by
squaring the ratio of the aircraft speed divided by the unaccelerated
stall speed in the current configuration.

Bob Faris

W.J. (Bill) Dean (U.K.). wrote:
I used to own an ASW20, Schleicher built early version with tip extensions.

From memory the handbook explained what was meant by "rough air", it was
described as a 15 m/s (30kt.) vertical gust. This might be running from
still air into 30kt. up, or into 30kt. down, or from say 10kt. down into
20kt. up. The handbook also said that it was possible to find air rougher
than that, for instance when running close to mountain ridges, in rotor, or
in thunderstorms; and that if there was a risk of this lower speeds should
be used.

I think the possibility and danger of rougher air is obvious, after all what
would happen if you tried soaring a big twister? I think that for a while
you would go up very fast, but in bits.

I have been looking at the book "Exploring the Monster". On 25th April
1955 Larry Edgar flying solo in the Pratt-Read was unable to keep out of the
rotor, and the glider broke up, being subjected to at least 15G. He had
entered the cloud at about 65 knots and had encountered a gust of about 85
knots horizontal speed and a very large change in vertical speed. I
suggest that no glider ever built could withstand this sort of thing, and if
the glider could the pilot could not.

As for manoeuvring speed, this is the limit speed for full deflection of any
one control. Use another control as well and you are outside limits.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Wayne Paul" wrote in message
...

I have been watching this thread for a while now.

The term "rough air" seems somewhat subjective. Review of the various
aerodynamic manuals in my personal library does not give me a clue to what
gust load is used in rough air limit calculations or its' relationship to
the V-n diagram.

I am sure there is a precise definition which is used in to determine
performance limits. Could anyone provide the gust load definition of
"rough air?"

Respectfully,

Wayne
http://www.soaridaho.com/Schreder