On Jul 29, 10:25*pm, "JR Weiss" wrote:
wrote:
In passenger jet aircraft you will notice usually 4 of these 'vanes'
mounted to either side of the cockpit. *An A320 has two either side
an A380 no less than 4 either side. *(Pre FBW these were seperate
for pilot an co pilot)
In Jets you will usually see similar vertical vanes mounted on the
nose to measure side slip.
A modern stall warning system uses not only Angle of Attack but side
slip to calculate stall warnings since the prescence of side slip
effects stall angle, presumably due to the greatee distance the air
must flow over the wing during side slip.
Thank you very much for your reply. Military fighter and attack planes
have angle of attack displays visible to the pilot. Do you see any
advantage to having something like this for pilots of airliners,
possibly for use as part of normal flying routine, possibly as a back-
up and cross check for airspeed information?

Unfortunately, the "experts" in the Transport Category Airplane world
have deemed AOA readouts as superfluous. *Their argument (among others)
is that optimum AOA for any particular operation is not constant for a
large range of gross weights, so Vref or V2 as defined by the FAA and
other regulatory agencies is "better."

After 20 years of aircraft carrier operations and 11 years of airline
operations I tend to disagree, but I'm not an aerodynamicist...

FWIW, the sideslip vanes may be on Airbusses, but they're not on the
747, and I haven't noticed them on any other Boeings. *Harriers had
them, and Tomcats had yaw strings (simple and effective).

Hi John;

I've heard the same thing from the airline industry, and I think they
might have a point. I've always wondered how you guys handle the vast
differences in gross weights you have when you arrive at the initial
approach fix.
The Navy as we both know, requires a very stable approach profile so
AOA is great for them, as it automatically compensates for the
differences in approach weight and the approach is the same AOA
regardless of weight. But this assumes a fairly (or at least
comparatively anyway) narrow gross weight for the Navy when arriving
for the approach on the boat.
You guys in the majors deal with what could loosely be described by a
Navy fighter pilot as a fair to middling gross weight range on
approach. My guess would be that using an optimum AOA on approach
might very well not be as viable as using a Vref. I would of course
bow to your better judgment on this since you have time in the big
boys and I don't.
I remember seeing a report from Boeing a while back where they were
"discussing" the addition of AOA to the approach equation both with
adjusted procedures and panel changes regarding instrumentation.
If I remember right, the bottom line on their research was that the
front offices and chief pilots of various majors couldn't reach a
consensus on the issue strong enough to warrant a major policy change
at the top level. There were specific lines who were willing to have
their panels equipped with a change from a peripheral AOA indicator to
a prominent place on the glass for an AOA tape on the approach mode,
but I never followed this through enough to discover were if anywhere
everybody went with all this.
Dudley