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**JR Weiss[_2_]**

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).