|
"Orval Fairbairn" <orfairbairn@earthlink.net> wrote in message
news:orfairbairn-873079.23211516052007@news.west.earthlink.net...
| In article <fvJ2i.193$dS1.175@newsfe03.lga>,
| N114RW <qwerty_265@charter.net> wrote:
|
| > Can someone Osplain this to me? I've no idea if I've it right,
or not.
| >
| > As I understand it, maneuvering speed is the speed above which the
| > aircraft may be damaged due to full control movements. Below that
| > speed, the plane will stall before damage occurs. I also understand
| > that maximum lift changes as the square of the speed, while stall
speed
| > changes as the square root of the weight.
| >
| > So, if I've an aircraft traveling at twice stall speed, it will
have 4
| > gšs acceleration prior to stalling. If I double the weight, the
stall
| > speed increases by 1.41, so maneuvering speed also increases by
1.41
| > assuming that the aircraft is rated a 4 gšs at both weights.
| > Or, to put it conversely, the maneuvering speed varies inversely
| > proportionately to the square root of the weight change if I
double
| > the weight, the maneuvering speed increases by 41%.
|
|
| > Do I've that right?
|
|
| No. At higher weights the airplane will stall at a lower G loading
than
| at light weights, since the wing stalls at the same total lift
generated.
|
| It takes more lift to carry the higher weight. Other structural
| components also carry load, such as engine mounts, tail components,
seat
| brackets, etc. Those components may actually be the determinant for
the
| max G loading, rather than the wing.
|
It has been along time, but if my memory is correct, Full deflection is
part of the equation, but wind shear, or gusts, play a part too. Here is
an article that may help:
http://www.flyingmag.com/article.asp?section_id=12&article_id=527&print_page=y
From paragraph seven-- "Va is a calculated airspeed based on the actual
gross weight of the airplane and the wing's response to a 50-foot per
second wind gust, or movement of the elevator. There are certification
limits for the loadings caused by the gusts of turbulence, for
maneuvering with the flight controls, and the combination of gusts and
maneuvering. Va is at the corner of the combined gust and maneuvering
limit. What we were taught, and believed, about not being able to break
the airplane with the controls when flying at or below Va is mostly true
when it comes to the elevator, but the elevator may break." And from
paragraph eight-- "The loads on an airplane are complicated because
gusts are not symmetrical, and because the flight controls exert their
own bending and twisting loads when they are deflected. That's why each
element of the airframe and its flight controls have their own design
limit loads. When controls are moved in combination, and there is
turbulence, the calculation of the loads on the airframe become very
complex and Va doesn't offer structural immunity in every situation."
--
Jarhead
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|
Re: Manovering Speed
