Slip indicators

[low n' slow]

Hi all. I've just got a quick question regarding slip indicators on modern aircraft, say the A320 or 737-NG for example. How is the slip indication generated? I'm quite sure it comes from the ADC/IRS but how is it generated in these units? What I'm getting at is, are beta probes used in the same way there are alpha probes (as seen on some fighters?).

Thanks/ LnS

[rudderrudderrat]

Hi low n' slow,
are beta probes used in the same way there are alpha probes (as seen on some fighters?)
I've never seen any such probes on A320s.
The FCOM simply says the FACs modify the sideslip indication slightly to show the pilot how much rudder to use ... (ailerons & spoilers retracted).

We used to do the same on 707s - simply apply rudder until you don't need any aileron, and bank slightly into the live engines to maintain heading.

As gum's would say - done by feel - didn't need a Beta target.

[Meikleour]

Some early model B747s had a yaw vane fitted under the nose just forward of the nosewheel bay. This was linked to the yaw dampers in an attempt to prevent "snaking".
The system didn`t work very well and was removed on my company`s aircraft.

[de facto]

Hi there,

On the 737 NG , the slip indicator (lower portion of the bank pointer)shows the lateral acceleration of the aircraft.
The linear accelerations are calculated by the Inertial reference Processor which gets its movement data from the IRS Gyros and accelerometers.
THis info is then sent to some data receiver which forwards to the DEUs (to convert the info into a video signal) which is sent to to the pilot Display unit in the form of a bank slip/skid indicator.
If the ADIRU senses a roll ATTitude of more than 35 degrees its color will change to amber.

When the aircraft goes through turbulence which may cause some lateral acceleration,the stall management yaw damper will soften the disruption by moving the rudder up to 2 degrees with flaps up.

The pilot only use of this feature in practical terms is when faced with an engine failure and in manual flight as he will see if his rudder input is insufficient or excessive for the bank he is using...

hope that helps..

[low n' slow]

Thanks all for the thurough explanations, particularly the info about the yaw vane on the early 747's.

/LnS